Evaluation of industrial based adsorbents for simultaneous removal of arsenic and fluoride from drinking water

Evaluation of industrial based adsorbents for simultaneous removal of arsenic and fluoride from drinking water

Accepted Manuscript Evaluation of industrial based adsorbents for simultaneous removal of arsenic and fluoride from drinking water Sadia Bibi, Abida F...

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Accepted Manuscript Evaluation of industrial based adsorbents for simultaneous removal of arsenic and fluoride from drinking water Sadia Bibi, Abida Farooqi, Assistant Professor Khadim Hussain, Naghma Haider PII:

S0959-6526(14)00960-3

DOI:

10.1016/j.jclepro.2014.09.030

Reference:

JCLP 4715

To appear in:

Journal of Cleaner Production

Received Date: 28 January 2014 Revised Date:

5 September 2014

Accepted Date: 8 September 2014

Please cite this article as: Bibi S, Farooqi A, Hussain K, Haider N, Evaluation of industrial based adsorbents for simultaneous removal of arsenic and fluoride from drinking water, Journal of Cleaner Production (2014), doi: 10.1016/j.jclepro.2014.09.030. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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Evaluation of industrial based adsorbents for simultaneous removal of arsenic and fluoride from drinking water Sadia Bibi1, Abida Farooqi1*, Khadim Hussain2 and Naghma Haider2

Corresponding Author: Abida Farooqi (Assistant Professor)

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Environmental Hydro geochemistry Laboratory, Department of Environmental Sciences, Faculty of biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan Geoscience advanced research laboratories, Chak Shahzd, Islamabad, Pakistan

Email: [email protected]

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Phone #: +92-5190644139

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Address: Department of Environmental Sciences, Faculty of biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan

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Abstract

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drinking water has global significance due to their easy and widespread availability. Present

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study aimed to assess selected industrial waste materials for simultaneous removal of arsenic and

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fluoride from drinking water in order to find cost effective adsorbent. Commercially available

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Hydrated Cement, Marble Powder (waste) and Brick Powder (waste) were used. Adsorbents were

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characterized by using X-Ray Diffractrometry techniques. The surface morphology of adsorbents

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was studied by Scanning Electron Microscopy (SEM). Batch adsorption tests were employed to

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evaluate the percent removal and adsorption capacity of adsorbents, under optimum conditions

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of adsorption time, dose, pH and adsorbate concentration. Removal percentage of studied

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adsorbents followed the decreasing trend: Hydrated Cement>Bricks Powder>Marble Powder.

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Hydrated Cement showed highest percentage removal, 97% and 80% for arsenic and fluoride

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respectively and was selected as the best media at neutral pH compared to other four adsorbents

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substantiating its potential for the drinking water treatment process. The applicability of the

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adsorbents for As was assessed under natural conditions with As contaminated groundwater

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samples collected from Tehsil Mailsi. In order to determine maximum adsorption capacity of

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adsorbents and to understand the nature of reaction on their surfaces, Langmuir and Freundlich

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isotherm were calculated. This study revealed that this new adsorbent (Hydrate Cement) is

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indigenous, easily available and could be easily applied in order to diminish the arsenic and

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fluoride pollution from drinking water.

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Keywords: Arsenic, Fluoride, removal %, Separation factor, Langmuir isotherm, Freundlich isotherm

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Evaluating the ability of industrial based adsorbents to remove arsenic and fluoride from

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Highlights (for review) 

Simultaneous removal of arsenic and fluoride from drinking water.

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Industrial waste materials used for the removal of arsenic and fluoride.

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Hydrated Cement, Marble Powder and Bricks Powder are efficient and cost effective adsorbents.

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XRD and SEM were performed to assess the surface morphology of adsorbents.

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Hydrated Cement, Marble Powder and Bricks Powder used first time for the simultaneous removal of arsenic and fluoride.

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1. Introduction

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Recognized as highly toxic elements, arsenic and fluoride are both contributors to the global

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water crisis, with significant health problems resulting from drinking water. This situation has

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become more serious due to increasing groundwater consumption in many countries like

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Pakistan, Bangladesh, India, and Nepal in the Indo region due to resource pressures from

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growing populations as well as surface water contamination (Farooqi et al., 2007; Kanel et al.,

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2006; Muhammad et al., 2010; Smedley and Kinniburgh, 2002).

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Arsenic is of serious concern because of its marked negative impacts to human health that range

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from acute lethality to chronic and carcinogenic effects (Abernathy et al., 2003). Most

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environmental arsenic problems are the result of mobilization under natural conditions.

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However, mining activities, combustion of fossil fuels, use of arsenic pesticides, herbicides, crop

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desiccants, wastewater discharge from mining/industry and use of arsenic additives to livestock

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feed create additional impacts. Arsenic and its derivatives are being used for many years and still

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they are in use like in electronics, material sciences and in medicines (Mudhoo et al., 2011;

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Baidya et al., 2006; Ghosh et al., 2007; Mukherjee et al., 2003; Tseng, 2004). Arsenic is present

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in a variety of forms, organic and inorganic, and oxidation states, in which the valances depend

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on the pH and redox conditions (Abernathy et al., 2003; Saha et al., 1999). At ambient water pH

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6 to 9, the predominant forms are: As-III (Arsenite) present as Arsenious Acid H3AsO3 and As-V

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(Arsenate) present as anions H2AsO4- and HAsO42-(Mudhoo et al., 2011; Kumaresan, 2001). At

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low pH, in the presence of sulfide, HAsS2 can be formed; arsine, arsine derivatives, and arsenic

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metal can occur under extremely reducing conditions (Mudhoo et al., 2011; Kumaresan, 2001).

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All inorganic compounds of arsenic are toxic, in particular present in trivalent form. Acute

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exposure to arsenic results in gastrointestinal effects (nausea, diarrhea, abdominal pain) that

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occur within 30 minutes. The central and peripheral nervous systems can also be affected,

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leading to heart failure. Chronic inhalation exposure to inorganic arsenic in humans is associated

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with irritation of the skin, causing Blackfoot disease, and strongly associated with lung, skin,

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bladder and liver cancers. Chronic oral exposure results in gastrointestinal effects, anemia,

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peripheral neuropathy, skin lesions, hyper pigmentation, and liver or kidney damage in humans

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(Mudhoo et al., 2011; Baidya et al., 2006; Ghosh et al., 2007; Mukherjee et al., 2003; Tseng,

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2004) . The US Environmental Protection Agency (EPA) has classified inorganic arsenic as a

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Evaluation of industrial based adsorbents for simultaneous removal of arsenic and fluoride from drinking water

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Group A human carcinogen (EPA, 1999). Arsenic contamination has aroused attention due to

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groundwater levels in many parts of the world at much higher concentrations than the World

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Health Organization (WHO) guideline of 10 µgL-1 (Saha et al., 1999). However, many countries

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including Pakistan have retained the earlier WHO guideline of 0.05 mg L−1 arsenic as the

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national standard or as provisional target (Muhammad et al., 2010). One of the major sources of

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arsenic exposure by the general population is drinking water (Bissen and Frimmel, 2003; Saha et

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al., 1999)

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Fluoride is essential to prevent dental caries but an excess intake is detrimental to human health.

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The suitable level of fluoride ions in drinking water specified by the WHO is 1.5 mg L-1

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(Tripathi et al., 2007). However, the concentration of fluoride ion in groundwater is higher than

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1.5 mg L-1 in many areas throughout the world. (Farooqi et al., 2007; Muhammad et al., 2010)

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Many technologies have been developed for removing arsenic or fluoride from groundwater.

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Several treatment technologies have been adopted to remove arsenic from drinking water under

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both laboratory and field conditions. The major mode of removing arsenic from water is by

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physico-chemical treatment. Technologies for the removal of arsenic from drinking water

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include

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coagulation/precipitation/adsorption/filtration (Zhang et al., 2002). Out of these, adsorption is

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evolving as a front line of defense. The traditional method of removing fluoride from drinking

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water are liming (Sollo et al., 1978) precipitation and coagulation (Tressaud, 2006), activated

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alumina (Ghorai and Pant, 2005), alum sludge (Sujana et al., 1998) and calcium (Huang and Liu,

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1999) have been widely investigated. In addition, ion exchange (Meenakshi and Viswanathan,

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2007; Popat et al., 1994), reverse osmosis (Viswanathan and Meenakshi, 2009) and

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electrodialysis (Adhikary et al., 1989) have also been studied for the removal of excess amounts

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of fluoride from drinking water. However, the shortcomings of most of these methods are high

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operational and maintenance costs, secondary pollution (generation of toxic sludge, etc.) and

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complicated procedure involved in the treatment. However, only few studies have been carried

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out to investigate the simultaneous removal of arsenic and fluoride, although both contaminants

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can co-present in groundwater in many cases (Devi et al., 2008).

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Among various methods used for arsenic and fluoride removal, attention has recently focused on

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adsorption process. It is being widely used because it offers satisfactory results and seems to be a

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methods

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adsorption,

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more attractive method in terms of cost, simplicity of design and operation (Mohapatra et al.,

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2009). Recently, researchers have devoted their attention on different types of low cost but

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effective materials. Widespread industrial activities generate huge amount of solid waste

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materials as by products. One of the beneficial uses of these wastes is to convert them as

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inexpensive sorbents (wherever applicable) for the detoxification of water. Various treated and

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untreated industrial wastes have been examined for arsenic and fluoride removal from water

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(Yadav et al., 2006; Kagne et al., 2008). However, challenges such as access to real low-cost

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adsorbents for simultaneous removal of arsenic and fluoride, simpler processes for development

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at local levels, sufficient availability, and high removal efficiency on real groundwater conditions

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such as the existence at neutral pH are still prevailing. These challenges have to be solved for

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developing efficient fluoride and arsenic removal technology for rural areas in developed and

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undeveloped countries. With this perspective, current work was taken to explore the feasibility of

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arsenic and fluoride adsorption from aqueous solutions and real groundwater with hydrated

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cement (commercially available), marble powder and bricks powder (industrial waste) as

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adsorbents. These adsorbents are easily available in almost all rural areas of Pakistan. Based on

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the review of literature, these adsorbents have not previously been investigated for their potential

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to adsorb arsenic and fluoride from water simultaneously. Hence an attempt has been made in the

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present work to evaluate these materials for simultaneous removal of As and fluoride from water.

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2.1

Materials

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2. Materials and methods

All chemicals used were of regent grade and used without further purification. Solutions were prepared by Milli-Q water (Q-H2O, Millipore Corp. with resistivity of 18.2MΏ-cm). Plastic ware (Polypropylene) used throughout the experiment to avoid metal contaminations were cleaned with 1% HNO3 and rinsed several times with deionized water before use. A total of 3 adsorbents including two industrial waste materials Marble waste and Bricks Powder and commercially available Cement were tested for their ability for arsenic and fluoride removal.

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2.2

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obtain fine powder. The bricks powder was washed several times with distilled water till clear

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water was obtained and oven dried at 105ºC for 12 h. The dried material was sieved to separate

Preparation of adsorbents

Bricks pieces were collected from brick kiln, washed with distilled water, dried and ground to

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less than 300 um size of particles for the present study.

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About 1000 g (1 kg) of commercially available cement was taken in a vessel and the required

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amount of distilled water (500 mL) was added. The pH of the cement in distilled water was about

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9. It was kept for 72 h at room temperature for hydration. After hydration/air-drying, clinkers

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were broken into small granules of 1.4–3 mm size.

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Marble powder used in this study was obtained, free of charge, from marble processing

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workshop was sieved and practical size 50 µm were used in present study. Samples were oven

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dried for 2h at 125 °C then cooled at room temperature, packed in stopper bottle and stored in

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desiccators for future use.

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A 100 mg L-1 fluoride stock solution was prepared by dissolving 221 mg NaF (analytical grade)

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in 1000 mL distilled water. F- ions bearing solutions were prepared by diluting the stock solution

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to different concentrations (5 mgL-1, 15 mgL-1, 30 mgL-1) with deionized water. Concentration

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of F- ions was analyzed with a F- selective electrode connected to an ion meter (Orion, 868).

Reagents and stock solutions

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Arsenic stock solution of 1000 µg mL−1 was prepared from atomic absorption standard (Perkins

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Elmer, USA), working standards were prepared by serial dilution of stock in deionized water.

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Hydride Generator Atomic Absorption Spectroscopy was used for the analysis of arsenic

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(Perkins Elmer Hitachi). 0.1 M solutions of HCl and NaOH were prepared in deionized water for

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pH adjustment.

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2.4 Chemical analysis and sample Characterization of adsorbents 2.4.1

X-Ray Diffraction Measurements (XRD)

X-ray powder diffractometry was performed to characterize the mineralogy of hydrated cement,

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waste marble powder and bricks powder samples. Three gram aliquots of the research splits were

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dry pulverized with a mortar and pestle to an average particle size of about 50-150 µm. About

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one gram of each specimen was then packed in an aluminum sample holder and analyzed with a

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Scintag X-1 Automated Diffractometer at a scan speed of 1°2θ in 2 min and a step size of 0.02° 6

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using a Ni-filtered Cu-Kα radiation 2.4.2

Scanning Electron Microscope

Scanning Electron Microscope JSM-6610 LV was used for the surface studies of adsorbent materials. Using the optimized conditions for the adsorption of arsenic and fluoride, the loaded

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mass was filtered, washes and dried at 105ºC for 30 min and cooled to room temperature. A

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blank mass (unloaded) was also subject to the same conditions and both the loaded and unloaded

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mass was subjected to SEM to check the changes on the surface of the mass before and after

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loading by the adsorbate molecules. The micrographs were taken at different resolutions from

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500× to 10,000×.Scanning Electron Micrographs of the adsorbent material with and without

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arsenic and fluoride loaded samples at different magnifications i.e., 500× to 100,000× were used

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to study the surface characteristics of the adsorbent material after selecting optimum conditions

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for adsorption.

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2.5 Batch experiments

Effects of various control parameters were investigated batch wise in Erlenmeyer flasks using different amounts of adsorbent material (10–40 g) with varying amounts of adsorbate (100-1000

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µg L−1 for As and 5-30 mgL-1 for fluoride) maintained at room temperature (25 ± 3ºC). Flasks,

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along with test solution were shaken in horizontal shaker (Wise Shake SHO-2D, Witeg

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Germany) at agitation speed of 150 rpm for all experiments. At the end of desired contact time

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(30, 60 and 90 min), flasks were removed from shaker and allowed to stand for 2 min for settling

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the adsorbent. Then supernatants were filtered using Whatman no. 42 filter paper and filtrate

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samples were analyze in order to determine residual arsenic and F- ions concentration. The

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percentage sorption (Eq. 1) of the adsorbent was calculated by using the following formula:

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% Sorption



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(1)

Where Ci and Ce are the initial and equilibrium concentrations.

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2.6 Adsorption Isotherms

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species among liquid and adsorbent, based on a set of assumptions that are mainly related to the

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heterogeneity/homogeneity of adsorbents, the type of coverage and possibility of interaction

Adsorption isotherms are mathematical models that describe the distribution of the adsorbate

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between the adsorbate species. Adsorption isotherms give a quantitative relationship between the

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solute concentration in the solution and the amount of solute adsorbed per unit mass of the

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adsorbent. In the present study, two of the isotherms, Langmuir and Freundlich, were applied to

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the experimental data to check its credibility. In present study, the amounts of adsorbents were

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added to a specific volume of arsenic and fluoride containing solutions of known concentration

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and the removal was calculated by determining the remaining amount of arsenic and fluoride

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after the adsorbent was made to stand in the solution up to already known equilibrium time. The

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same data was used for Langmuir isotherm and Freundlich Isotherm.

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3. Results and discussion 3.1 Adsorption studies 3.1.1 Effect of time on adsorption

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The results of time required to reach equilibrium for arsenic and fluoride were shown in Figure 1(a-c). Test solutions of 100 µgL-1adsorbate concentrations of arsenic and 5 mgL-1 of

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fluoride were investigated using 10 gL-1, 20 gL-1, 30 gL-1and 40 gL-1 of adsorbents mass at pH

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8.0. Study revealed, an initial increase of arsenic and fluoride removal with increased contact

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time, but gradually it approached to an almost constant value, denoting attainment of

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equilibrium. When curves appeared nearly asymptotic to the time axis was assumed as

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equilibrium time.

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time up to 30 min for all the studied adsorbents (Hydrated cement, Bricks powder and Marble

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powder) and it became maximum at 60 min and attained saturation. No significant effect on

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equilibrium was observed for further time increase up to 90 min. The short equilibrium time

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indicate rapid rate of reaction and presence of a large number of adsorption sites on adsorbents.

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Therefore, further studies were carried out using 60 min contact time for all the adsorbents

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(Table 1a). Fluoride adsorption profile also was very similar to As, which showed a rapid

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increase initially and reached equilibrium within 60 min. So 60 minutes equilibrium time was

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selected as optimum, for further studies (Table 1b).

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Fig. 1 (a-c) showed that for As, sharp increase in adsorption curve was observed by increasing

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Initially, the adsorption was fast, probably due to initial concentration gradient between

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the adsorbate and the number of vacant sites available on the adsorbent surface (Bhatnagar et al., 8

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2010) and later on the adsorption rate geared until saturation. This may be due to limited mass

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transfer of the adsorbate molecules to the external surface of adsorbent from the bulk liquid.

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Several parameters determine the equilibrium adsorption time. These include agitation rate in the

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aqueous phase, physical properties of the adsorbent (surface charge density, porosity and surface

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area), amount of adsorbent, properties of the ions to be removed, concentration of ionic species

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and the presence of other metal ions that may compete with the ionic species of interest for the

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active sites (Say et al., 2003).

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3.1.2 Effect of adsorbent dose

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get the tradeoff between the adsorbent dose and the percentage removal resulting in an optimum

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adsorbent amount. To determine the effect of adsorbent dosage on the percent adsorption (i.e.

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uptake of arsenic and fluoride) study was conducted in the range of 10–40 gL-1using optimum

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equilibrium contact time of 30 and 60 min at pH 8.0 with arsenic and fluoride concentration of

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100µgL-1 and 5mgL-1 respectively.

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Percent removal of arsenic increased by increasing adsorbent dose up to 30 gL-1 with sorption efficiency of 98.8% for Hydrated Cement, 96.4% for Bricks Powder and 95.3% for Marble Powder. Further increase in adsorbent dosage up to 40 gL-1 caused no effect on the percent removal of arsenic Fig.2 (a-c) (Table 2a ).Similarly 30 gL-1 was an optimum dose for fluoride adsorption (Hydrated Cement 99%, Bricks Powder 88% and Marble Powder 94%) (Table 2b). The removal of arsenic and fluoride was enhanced with increasing adsorbent material dosage shown in Fig 2.(a-c),because of increase in the number of active sites as the adsorbent material dosage increased (Al-Garni et al., 2009). Increase in adsorption efficiency by increasing adsorbent concentration (from 20 to 30gL-1), lead to the corresponding increase in adsorption sites (Chubar et al., 2005; Kamala et al., 2005) and stabilized afterward due to cell crowding, while it decreased with the increase of adsorbent concentration. On the basis of above mentioned results 30 gL-1was found optimum for arsenic and fluoride adsorption.

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Study on the effect of adsorbent dose for arsenic and fluoride removal was important to

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Effect of pH on adsorption efficiency

The pH of the solution also had a significant impact on the uptake of metals and ions since it determines the surface charge of the adsorbent, the degree of ionization and speciation of

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the adsorbate. The effect of pH in the range of 2–9 on removal of arsenic and fluoride using optimum adsorbent dosage of 30gL-1equilibrated for optimum 60 min as discussed earlier. As

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concentration of 100 µgL-1 and fluoride 5 mgL-1was studied in order to establish the effect of pH

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on the adsorption.

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optimum range of pH value. The percentage adsorption of arsenic was found to increase with an

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increase in pH up to 8 and then it decreased with a further increase of pH. The percentage

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removal of As is increased from 60% to 99 % with increasing the initial pH from 2 to 8. The

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sharpest increase in As uptake was obtained at pH=7 (99.9%) removal with Hydrated Cement

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and Marble powder and pH=8 (99.9%) removal with Bricks Powder, The sorption efficiency

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remained higher than 80% for when the pH was greater than 5 till 8, and decreased afterward

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(Fig. 3(a-c) and (Table 3a).

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It was found that the adsorption rate of As was parabolic, indicate that there exists an

Studies suggest that in strong acidic solution, several ions present in natural water

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competes with As for active adsorption sites and impedes adsorption process, and adsorption

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amount of As decreases with acidity increasing. While in alkaline solution, hydrates formed with

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hydrolyzation of As precipitate on the surface of adsorbents, and can decrease the adsorption

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activity. Moreover, the relative distribution of dissolved arsenic is influenced by pH and the

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redox conditions. This indicated that the effect of pH on the sorption of arsenic was in a good

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working range of water at house hold level. The WHO acceptable pH range of the potable water

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was 6.5–8.5, and these adsorbents can be used without pH adjustment. Similarly pH of the

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medium was one of the important parameters that significantly affect the extent of fluoride

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adsorption. The percentage adsorption of fluoride was found to increase with an increase in pH

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up to 8 and then it decreased with a further increase. The optimum pH for the removal of fluoride

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was found to be pH=7 (99%) removal with Hydrated Cement and (94%) removal with Marble

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Powder and pH=8 (92%) Bricks Powder (Figs. 3a-c) and (Table 3b).

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The lower adsorption efficiency of fluoride in acidic medium might be due to the formation of weakly ionized hydrofluoric acid, which reduces availability of free fluoride for adsorption. In alkaline conditions, lower adsorption may be due to the competition of OH ions with F− ions for adsorption because of similarity in F− and OH− in charge and ionic radius.

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Thus results indicated that the adsorption process was highly dependent on pH of solution

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and recorded higher adsorption capacities at pH 7 and 8 then pH 9. These findings attributed to

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the fact that the change in pH values can affect the surface charge of the adsorbent as well as the

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degree of ionization and speciation of the adsorbate. Keeping in view the normal pH range of

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potable water, pH 7 was selected for Hydrated Cement and Marble Powder and pH 8 for Bricks 10

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Effect of adsorbate concentration

Effect of adsorbate concentration on arsenic and fluoride removal was studied at different adsorbate concentrations of As (100 µgL-1, 500 µgL-1, and 1000 µgL-1) and F- (5 mgL-1, 15 mgL1 and 30 mgL-1) keeping string speed of 150 rpm, at optimum pH, adsorbent dose and contact time.

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3.1.4

The results indicated that arsenic removal efficiency was high at lower concentrations up to 100 µg L-1 with removal efficiencies of 98.8% for Hydrated Cement, 95% for Marble Powder and 91% for Bricks Powder, respectively and decrease with the increase in concentration. However, (Figs. 4a-c) % removal efficiencies were still higher than 90% up to the concentration of 1000 µgL-1 for Hydrated Cement and Bricks Powder and higher than 80% for Marble Powder

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Powder for further studies.

(Table 4a ).Similarly in case of fluoride adsorption efficiency was high at low concentration and it decreases with increase in fluoride concentration. Hydrated Cement showed higher adsorption efficiency of 99% at fluoride concentration of 5 mgL-1; however the removal efficiency was higher than 80% up to the concentration of 30 mgL-1. Similarly for Marble Powder and Bricks

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It is worth noting that nature of adsorbent and the available adsorption sites were most

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important parameters affecting the rate of adsorption. The mechanism of solute transfer to the

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solid includes diffusion through the fluid film around the adsorbent particle and diffusion

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through the pores to the internal adsorption sites (Kamala et al., 2005). In the initial stages of

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adsorption of As and F-, the concentration gradient between the film and the available pore sites

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was large, hence the rate of adsorption was faster. The rate of adsorption decreased in the later

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stages of the adsorption probably due to the slow pore diffusion of the solute ion into the bulk of

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the adsorbent. At low concentration, the ratio of available surface to the arsenic and fluoride

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concentration was larger, so the removal was higher. However, in case of higher concentrations,

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this ratio was low; hence, the removal percentage was lesser.

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Powder adsorption efficiency decreased with increase in concentration. However it remained higher than 75% for fluoride concentration of 30 mgL-1 (Table 4b).

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3.2 Applicability of adsorbents under natural water conditions Present study demonstrated the potential of different adsorbent materials (Hydrated

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Cement, Marble Powder and Bricks Powder) for the removal of As from naturally As

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contaminated ground water. The applicability of the adsorbents was assessed by using As 11

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contaminated groundwater collected from Tehsil Mailsi. Table (1) summarizes all the physico-

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chemical parameters of contaminated water samples and removal efficiency of the proposed

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adsorbents. Adsorption experiments were carried out under the optimum conditions. Results

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indicated that arsenic removal efficiency of proposed adsorbents under natural conditions was

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well suited for potable water applications. In a set of experiments the adsorbents demonstrated

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>800 µg/l of As present in contaminated ground water could be removed >90% for Hydrated

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Cement and Marble Powder and >85% for Bricks Powder under the aforementioned optimum

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conditions. Thus, it could be recommended for the successful removal of arsenic from

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groundwater of affected areas. The results of water quality before and after adsorption of studied

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water samples were shown in Table (1). It might be seen that after adsorption, As was reduced to

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a value < 50µgL-1 for Hydrated Cement and Marble Powder which was within the Pak EPA

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permissible limits (50 µgL-1) clearly showing the efficiency of adsorbents for the removal of As

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ions from understudy groundwater samples by increasing the adsorbent dose most of samples

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could be brought under the permissible limit set by WHO of 10 µgL-1.

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The Langmuir model assumes monolayer adsorption onto homogeneous surface with a

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finite number of identical sites and maximum adsorption occurs when the surface was covered

22

by the adsorbate (Dodd et al., 2006) (Eq. (2)) 







     

(2)

EP

23

Where, qe is the sorbed concentration (mass of adsorbate/mass of adsorbent), qm the maximum

25

capacity of adsorbent for the adsorbate (mass of adsorbate/mass of adsorbent), C was the initial

26

concentration of adsorbate in solution (mass per unit volume) Kads the adsorbate affinity for

27

adsorbent. A plot of 1/q against 1/C produced a straight line with an intercept of 1/qm and A

28

slope of 1/qm.Kads for As (Fig. 5a) and F-(Fig. 5b).

29 30 31 32 33 34 35

Hydrated Cement, Bricks Powder and Marble powder showed a good fit to the linearized Langmuir model both for As (R2=0.99 for all adsorbents) and fluoride (R2=0.99 (Hydrated Cement) and R2= 0.98 (bricks Powder and Marble) (Table 2a and 2b). Maximum adsorption capacity of adsorbents was found in order of Hydrated Cement>Bricks Powder>Marble Powder both for arsenic and fluoride. Hydrated cement had maximum adsorption capacity of 1.92 mgg-1 and 1.72 mgg-1 for arsenic and fluoride respectively. While for Bricks powder and Marble waste

AC C

24

12

ACCEPTED MANUSCRIPT

it was found 0.04 mgg-1 for arsenic and 0.84 mgg-1 and 0.18 mgg-1 for fluoride respectively. The essential characteristics of Langmuir isotherm and adsorption favorability could be expressed in terms of dimensionless constant called the separation factor or equilibrium parameter (RL), which was defined by the following equation (Eq. 3) (Saifuddin M and Kumaran, 2005): 

5



(3)

 !

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1 2 3 4

6 7 8 9 10

Where Kads was the Langmuir constant and Ci was the initial concentration of arsenic and fluoride with different concentration as mentioned from (100–1000µgL-1) and (5-30 mgL-1) respectively. The value of RL indicates the nature of adsorption as unfavourable (RL > 1), linear

11

arsenic and fluoride indicate highly favourable adsorptions of As and fluoride on Hydrated

12

Cement, Bricks Powder and Marble at all concentrations (Table 3a and 3b.).

SC

3.3.2 Freundlich adsorption isotherm

M AN U

13 14 15 16

(RL = 1) favourable (0
The Freundlich equation deals with physicochemical adsorption on heterogeneous

17

surfaces (Chassapis et al., 2010). The Freundlich adsorption isotherm is the most widely used

18

mathematical model in aqueous systems. Freundlich proposed the following expression (Eq. 4)

19

for the adsorption from solutions, on the basis of absorption studies:

20 21 22 23

On the basis of this assumption there were different active sites on the adsorbent surface

24

that had different affinities for different adsorbate; the Freundlich Isotherm could be derived

25

from the Langmuir isotherm model. Where K was the measure of capacity of adsorbent, (n) the

26

measure of change in affinity for the adsorbate with a change in adsorption density in the above

27

equation. The linearized form (Eq. 5) of the equation (4) could be used to plot the Freundlich

28

isotherm:

30

( ) '

TE D

(4)

EP

AC C

29

"# $% &



*+,"# *+,$  ' *+,%

(5)

A plot of log qe against log C produced a straight line with a slope of 1/n and an intercept

31

of log k. Values of R2=0.99 (Fig. 6a) indicated that As data for Bricks Powder fits to the

32

Freundlich Isotherm. While R2=0.86 (As) and R2=0.85 (Fluoride) for Hydrated Cement and

33

R2=0.79 (As) and R2=0.78 (Fluoride) for Marble Powder indicates that the experimental data

34

fitted well to Freundlich model but was not good as Langmuir model (Fig. 6b) (given as Table 2a

35

and 2b). The constant ―n‖ gives an indication of how favorable the adsorption processes were.

36

The slop1/n was a measure of adsorption intensity or surface heterogeneity that represents the 13

ACCEPTED MANUSCRIPT

deviation from linearity of adsorption as follows: if the value of 1/n=1, the adsorption was linear,

2

1/n<1, the adsorption process was chemical, if 1/n>1, the adsorption was a favorable physical

3

process and adsorption was cooperative (Valko et al., 2007). However, it signified that surface of

4

the adsorbent under investigation was heterogeneous in nature (Streat et al., 2008). In case of

5

fluoride, for all adsorbents 1/n<1 indicate that adsorption process was chemical. While for As

6

1/n<1 for Marble powder, 1/n=1 for Hydrated Cement indicates adsorption was linear and 1/n>1

7

in case of Bricks Powder indicating adsorption as favorable physical process.

15 16 17 18 19 20 21 22

Mineralogy and Surface morphology of adsorbents

3.4.1

XRD analysis

SC

13 14

3.4

The identified crystalline phases of Marble Powder were calcite and dolomite. (Fig. 7a) Strong broad peaks between 30º, 39º, 47º and 49º (2θ) are characteristic of amorphous calcite (CaCO3) and small peaks at 31, 41 and 51 are characteristics of dolomite (CaMg)(CO3)2. It also contains SiO2, and small amount of Al2O3 and Fe2O3.

M AN U

8 9 10 11 12

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1

XRD spectra of Brick Powder (Fig. 7b) strong peeks at 21º, 25º and 50º are characteristic peeks of quartz. Small peeks at 26º indicate presence of albite and peeks at 33 and 35 indicate

24 25 26 27

presence of hematite.

28

characteristic peeks of portlandite. Peeks at 30º, 32º and 49º indicate presence of calcium

29

magnesium aluminum oxide silicate, di-calcium silicate and calcium aluminum oxide silicate

30

respectively. 3.4.2

EP

In XRD spectra of Hydrated Cement (Fig. 7c) two strong peeks at 19º and 34º are

AC C

31 32 33 34

TE D

23

Surface morphology of adsorbents

The surface morphology of adsorbents was studied by Scanning Electron Microscopy

35

(SEM). Fig 8, 9 and 10 showed loaded and unloaded mass of Marble powder, Hydrated Cement

36

and Bricks powder. Fig 8a, 9a and 10a showed that adsorbents had uneven surfaces with large

37

number of pores spaces, which perhaps provides sites for adsorption of As and F either

38

physically or chemically. Fig 8b, 9b and 10b showed that the pores are fairly covered due to the

39

adsorption and aggregation of fluoride and arsenic, form layers that settled on the rough and 14

ACCEPTED MANUSCRIPT

1

irregular surfaces. Fig 8c, 9c and 10c micrographs had been taken on high resolution of 10,000×

2

by focusing on available pores which were shown in Figure 8a, 9a and 10a. These high

3

resolution micrographs indicate large number of irregular outgrowths providing high surface area

4

and more space for accommodation of arsenic and fluoride.

6

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5

3.5 Comparison of adsorbents efficiency and selection of best media

7 8

Three different inexpensive and easily available adsorbents were used in the present

10

study. Industrial materials (Bricks Powder and Marble Powder, while and Hydrated Cement

11

was prepared from commercially available cement) were used. They were compared in terms

12

of removal of arsenic and fluoride (% sorption), contact time and pH range. Absorbents were

13

individually screened for their ability to remove arsenic and fluoride from water.

M AN U

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9

The data in Table 4a-4b showed that best results were obtained by comparing industrial

17

waste materials Marble Powder and Bricks Powder with commercially available Portland

18

cement. The sorption efficiency was in order of Hydrated Cement >Bricks Powder >Marble

19

Powder with % removal of 97%, 95 % and 88% at As concentration of 1000 µgL-1

20

respectively. Similarly in case of fluoride order of sorption efficiency followed the same

21

pattern Hydrated Cement >Bricks Powder >Marble Powder and percentage removal of fluoride

22

was found 80%, 75% and 75% respectively. Order of sorption efficiency of all the five

23

adsorbents for adsorption of As and F was found as Hydrated Cement >Bricks Powder

24

>Marble Powder. Hydrated Cement was selected as the best media due to superior results

25

compared to other adsorbents.

EP

AC C

26 27 28

TE D

14 15 16

Comparison of adsorption capacity of different adsorbents used for removal of arsenic

29

and fluoride reported in the literature is given in Table (5). It appears that all adsorbents used in

30

this study specially Hydrated Cement had a reasonable potential as an adsorbent for the

31

removal of As and fluoride from aqueous solutions.

32

In the present study, the amounts of different adsorbents were added to a specific

33

volume of arsenic and fluoride containing solutions of known concentration and the removal of

34

arsenic and fluoride was calculated by determining the remaining amount of arsenic and

35

fluoride after the adsorbent was made to stand in the solution up to already known equilibrium 15

ACCEPTED MANUSCRIPT

1

time. The same data was used for Langmuir isotherm and Freundlich Isotherm. Bricks Powder and Marble Powder are easily available free of cost from brick kilns and marble

4

processing workshops. The author get the waste materials free of cost from the Brick kilns and

5

Marbel Processing companies. Commercially available cement cost 0.8 US $/ Kg and 30g

6

Hydrated Cement is enough to treat 1 L of water (removal % >90 for arsenic and >75 % for

7

fluoride from an aqueous solution of 1000 µgL-1 of As and 30 mg L−1 of fluoride). As adsorbents

8

are inexpensive so regeneration was not required. For the disposal the waste was solidified with

9

good quality cement and disposed into a concrete vault.

SC

10 11

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2 3

Conclusions

In present study, new adsorbents were studied for removal of arsenic and fluoride from

15

drinking water. The method was simple and had shown great potential for removal of arsenic

16 17 18

and fluoride. The main conclusions that can be drawn from the above study are given below:

M AN U

12 13 14

23

found to load as high as 1.92 mgg-1 and 1.72mgg-1 for arsenic and fluoride respectively.

24

While for Bricks powder and Marble waste it was found 0.04 mgg-1 for arsenic and 0.84

25

mgg-1 and 0.18 mgg-1 for fluoride respectively.

20 21

EP

19

TE D

22

1. All the adsorbents (Hydrated Cement, Bricks Powder and Marble Powder) showed removal % >90 for arsenic and >75 % for fluoride from an aqueous solution of 1000 µgL-1 of As and 30 mg L−1 of fluoride at pH 7.0 and 8, with the contact period of 60 min and a dose of 30 g L−1. 2. The adsorption followed the Langmuir adsorption isotherm model. Hydrated Cement was

3. The optimum pH was found to about 7 for arsenic and fluoride adsorption with Hydrated

27

Cement and Marble powder and pH 8 for Bricks Powder which made them very suitable for

28

use in drinking water treatment.

29

AC C

26

4. Other ions did not greatly affect the adsorption of arsenic thereby indicating that these adsorbents were selective adsorbent for arsenic.

30 31 32

5. The simple method developed for the removal of arsenic and fluoride could successfully

33

reduced the arsenic and fluoride levels to below drinking water limits and proved to be an

34 35 36 37

effective and rapid household method

Acknowledgment 16

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This work was supported by the Higher Education Commission Pakistan (Grant No. 1267),

References

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Baidya, K., Raj, A., Mondal, L., Bhaduri, G., Todani, A., 2006. Persistent conjunctivitis associated with drinking arsenic-contaminated water. J. Ocul. Pharmacol. Ther. 22, 208–211. Bhatnagar, A., Minocha, A., Sillanpää, M., 2010. Adsorptive removal of cobalt from aqueous solution by utilizing lemon peel as biosorbent. Biochemical engineering journal 48, 181-186. Bissen, M., Frimmel, F.H., 2003. Arsenic—a review. Part I: occurrence, toxicity, speciation, mobility. Acta hydrochimica et hydrobiologica 31, 9-18.

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the population exposed to arsenic through drinking water in West Bengal, India. J. Exp. Sci. Environ. Epidemol. 7, 215–223.

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Meenakshi, S., Viswanathan, N., 2007. Identification of selective ion-exchange resin for fluoride sorption. Journal of colloid and Interface Science 308, 438-450.

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Kagne, S., Jagtap, S., Dhawade, P., Kamble, S., Devotta, S., Rayalu, S., 2008. Hydrated cement: a promising adsorbent for the removal of fluoride from aqueous solution. Journal of Hazardous Materials 154, 88-95.

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Kamala, C., Chu, K., Chary, N., Pandey, P., Ramesh, S., Sastry, A., Sekhar, K.C., 2005. Removal of arsenic (III) from aqueous solutions using fresh and immobilized plant biomass. Water Research 39, 2815-2826. Kanel, S.R., Greneche, J.-M., Choi, H., 2006. Arsenic (V) removal from groundwater using nano scale zero-valent iron as a colloidal reactive barrier material. Environmental Science & Technology 40, 2045-2050.

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Kumaresan, M., Riyazuddin, P., 2001. Overview of speciation chemistry of arsenic. Curr. Sci. 80, 837–846.

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Zhang, W., Cai, Y., Tu, C., Ma, L.Q., 2002. Arsenic speciation and distribution in an arsenic hyperaccumulating plant. Science of the Total Environment 30

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Table 1a: Effect of time on adsorption of arsenic.

BP

MP

Time

Equilibirium As Conc. (Ce) (µg/l)

(Ci-Ce)

(Ci-Ce)/Ci

10 10 10 10 10 10 10 10 10

100 100 100 100 100 100 100 100 100

30 60 90 30 60 90 30 60 90

25.2 20.2 20 24.3 20.1 20.2 29.5 24.5 24.4

74.8 79.8 80 75.7 79.9 79.8 70.5 75.5 75.6

0.748 0.798 0.8 0.757 0.799 0.798 0.705 0.755 0.756

BP

MP

Time

5 5 5 5 5 5 5 5 5

10 10 10 10 10 10 10 10 10

30 60 90 30 60 90 30 60 90

74.8 79.8 80 75.7 79.9 79.8 70.5 75.5 75.6

Equilibirium F Conc. (Ce) (mg/l)

(Ci-Ce)

(CiCe)/Ci

Removal%

1.5 1.5 1.5 1.5 1.3 1.3 1.9 1.9 1.9

3.2 3.5 3.5 3.5 3.7 3.7 3.1 3.1 3.1

0.64 0.7 0.7 0.7 0.74 0.74 0.62 0.62 0.62

64 70 70 70 74 74 62 62 62

EP

HC

Mass of Adsorbent (g/l)

AC C

Adsorbent

Initial Conc. F (Ci) (mg/l)

TE D

Table 1b: Effect of contact time on adsorption of fluoride.

Removal %

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Mass of Adsorbent (g/l)

SC

HC

Initial Conc. (Ci) (µg/l)

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Adsorbent

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Table 2a: Effect of adsorbent dose on adsorption of arsenic.

MP

Equlibrium As Conc. (Ce) (µg/l)

(Ci-Ce)

(CiCe)/Ci

Removal%

20.4 13.9 1.2 1.2 20.1 10.5 3.6 3.6 24.5 10.7 4.7 4.7

79.6 86.1 98.8 98.8 79.9 89.5 96.4 96.4 75.5 89.3 95.3 95.3

0.796 0.861 0.988 0.988 0.799 0.895 0.964 0.964 0.755 0.893 0.953 0.953

79.6 86.1 98.8 98.8 79.9 89.5 96.4 96.4 75.5 89.3 95.3 95.3

TE D

BP

100 100 100 100 100 100 100 100 100 100 100 100

Mass of Adsorbent (g)/l 10 20 30 40 10 20 30 40 10 20 30 40

EP

HC

Initial Conc. (Ci) (µg/l)

AC C

Adsorbent

ACCEPTED MANUSCRIPT

Table 2b: Effect of adsorbent dose on adsorption of fluoride.

BP

(Ci-Ce)

1.5 0.9 0.05 0.05 1.3 1.2 0.6 0.6 1.9 0.8 0.3 0.3

3.5 4.1 4.95 4.95 3.7 3.8 4.4 4.4 3.1 4.2 4.7 4.7

(CiCe)/Ci

Removal%

0.70 0.82 0.99 0.99 0.74 0.76 0.88 0.88 0.62 0.84 0.94 0.94

70 82 99 99 74 76 88 88 62 84 94 94

EP

TE D

MP

Equlibrium F Conc. (Ce) (mg/l)

RI PT

5 5 5 5 5 5 5 5 5 5 5 5

HC

Mass of Adsorbent (g)/l 10 20 30 40 10 20 30 40 10 20 30 40

SC

Initial Conc. (Ci) (mg/l)

M AN U

Adsorbent

Adsorbent pH HC

2 3

Mass of Adsorbent (g) 30 30

AC C

Table 3a: Effect of pH on adsorption of arsenic Initial As Conc. (Ci) (µg/l)

Equlibrium As Conc. (Ce) (µg/l)

(Ci-Ce)

(CiCe)/Ci

Removal%

100 100

32.8 31.6

67.2 68.4

0.7 0.7

67.2 68.4

ACCEPTED MANUSCRIPT

70.1 88.3 91.4 98.8 88.5 67.3 65.3 66.6 71.1 75.0 80.2 84.5 96.4 83.1 67.1 67.5 71.1 84.3 85.8 95.2 81.1 72.4

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0.7 0.9 0.9 1.0 0.9 0.7 0.7 0.7 0.7 0.8 0.8 0.8 1.0 0.8 0.7 0.7 0.7 0.8 0.9 1.0 0.8 0.7

SC

70.1 88.3 91.4 98.8 88.5 67.3 65.3 66.6 71.1 75.0 80.2 84.5 96.4 83.1 67.1 67.5 71.1 84.3 85.8 95.2 81.1 72.4

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29.9 11.7 8.6 1.2 11.5 32.7 34.7 33.4 28.9 25.0 19.8 15.5 3.6 16.9 32.9 32.5 28.9 15.7 14.2 4.8 18.9 27.6

TE D

100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100

EP

MP

30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30

AC C

BP

4 5 6 7 8 9 2 3 4 5 6 7 8 9 2 3 4 5 6 7 8 9

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Table 3b: Effect of pH on adsorption of fluoride

MP

(Ci-Ce)

(CiCe)/Ci

Removal%

5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5

30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30

2.2 1.9 1.5 1.2 1 0.05 0.3 0.5 2.5 2.3 1.5 1.2 0.9 0.5 0.4 0.6 2.1 1.9 1.4 0.9

2.8 3.1 3.5 3.8 4 4.95 4.7 4.5 2.5 2.7 3.5 3.8 4.1 4.5 4.6 4.4 2.9 3.1 3.6 4.1

0.56 0.62 0.70 0.76 0.80 0.99 0.94 0.90 0.50 0.54 0.70 0.76 0.82 0.90 0.92 0.88 0.58 0.62 0.72 0.82

56 62 70 76 80 99 94 90 50 54 70 76 82 90 92 88 58 62 72 82

M AN U

SC

Equlibrium F Conc. (Ce) (mg/l)

TE D

BP

2 3 4 5 6 7 8 9 2 3 4 5 6 7 8 9 2 3 4 5

Mass of Adsorbent (g)

EP

HC

Initial F Conc. (Ci) (mg/l)

AC C

Adsorbent pH

ACCEPTED MANUSCRIPT

30 30 30 30

4.2 4.7 3.7 3.6

0.8 0.3 1.3 1.4

0.84 0.94 0.74 0.72

RI PT

5 5 5 5

TE D

M AN U

SC

6 7 8 9

Table 4a: Effect of adsorbate concentration on adsorption of arsenic.

HC

BP

Final Conc. (Ce)

100 500 1000 100 500 1000 100 500

4.81 42.30 119.00 1.20 10.10 31.72 3.60 18.34

(Ce-Ci)

(Ci-Ce)/Ci

% Removal

95.19 457.70 881.00 98.80 489.90 968.28 96.40 481.66

0.95 0.92 0.88 0.99 0.98 0.97 0.96 0.96

95.19 91.54 88.10 98.80 97.98 96.83 96.40 96.33

EP

MP

Initial Conc. (Ci)(µg/l)

AC C

Adsorbent

84 94 74 72

ACCEPTED MANUSCRIPT

951.64

0.95

Table 4b: Effect of adsorbte concentration on adsorption of fluoride.

MP

5 15 30 5 15 30 5 15 30

0.1 0.5 6.1 0.6 3.3 7.4 0.3 1.1 7.5

5.0 14.5 24.0 4.4 11.7 22.6 4.7 13.9 22.5

(CeCi)/Ce

Removal %

M AN U

(Ce-Ci)

TE D

BP

Equlibrium F conc. (mg/l) (Ce)

EP

HC

Initial F conc. mg/l (Ci)

AC C

Adsorbent

95.16

RI PT

48.36

SC

1000

1.0 1.0 0.8 0.9 0.8 0.8 0.9 0.9 0.7

99 97 80 88 78 75 94 93 75

ACCEPTED MANUSCRIPT

634 746 970 650 452

155 207 269 165 107

60 56 72 58 45

1074 1220 683 1044 781

75 170 100 80 100

206 815 971 412 313

21 29 13 32 20

SC

1.92 1.99 2.22 0.78 1.09

2 2 2 1 0

M AN U

7.6 7.3 7.8 7.4 7

TE D

Sargana Sargana Malsi Malsi Sargana

Total EC Mg+2 HCO3ClSO4-2 NO-1 Fe Zn As % Ca+2 Hardness MP (mg/l) (mg/l) (mg/l) (mg/l) (mg/l) (mg/l) (mg/l) (mg/l) (µg/l) (ms/cm) Removal (mg/l)

EP

pH

AC C

Sample

RI PT

Table 5: Physio-chemical parameters of ground water samples and As removal % of different adsorbents (Atta et al, 2014 unpublished data)

0 1 2 0 0

787 642 538 828 285

13 5 3 24 BDL

98 99 99 97 100

HC

% Removal

BP

% Removal

12 11 5 21 BDL

98 98 99 97 100

86 65 7 103 BDL

89 90 99 88 100

ACCEPTED MANUSCRIPT

Figure 6a: Isotherm parameters obtained from Langmuir model for adsorption of As Kads (l/mg) 0.12 0.16 0.03

R2 0.999 0.999 0.999

qm (mg/g) 1.92 0.04 0.04

RI PT

Adsorbents HC BP MP

Figure 6b: Isotherm parameters obtained from Langmuir model for adsorption of fluoride

qm (mg/g) 1.72 0.84 0.18

R2 0.997 0.985 0.980

SC

Kads (l/mg) 3.06 0.25 0.66

M AN U

Adsorbents HC BP MP

TE D

Table 7a: Separation Factor for As using different adsorbents

Adsorbents

EP

HC

AC C

BP

MP

Initial As Concentration (Ci) (µg/l)

KadsCi

RL

100 500 1000 100 500 1000 100 500 1000

12.4 62.0 124.0 15.6 77.8 155.6 2.6 13.2 26.4

0.075 0.016 0.008 0.060 0.013 0.006 0.275 0.071 0.037

ACCEPTED MANUSCRIPT

Table 7b: Separation Factor for fluoride using different adsorbents

MP

5 15 30 5 15 30 5 15 30

15.3 45.9 91.7 1.2 3.7 7.4 3.3 9.9 19.8

RL

RI PT

BP

KadsCi

0.1 0.0 0.0 0.4 0.2 0.1 0.2 0.1 0.0

SC

HC

Initial F Concentration (Ci) (mg/l )

M AN U

Adsorbent

Table 8a: Isotherm Parameters obtained from Frendulich model for adsorption of As Adsorbents MP BP

K

R2

0.5 1.5

0.2 0.4

0.999 0.992

1.0

1.2

0.996

TE D

HC

n

Table 8b: Isotherm Parameters obtained from Frendulich model for adsorption of fluoride

n

K

R2

MP BP HC

0.3 0.2 0.4

0.9 1.3 2.5

0.785 0.990 0.857

AC C

EP

Adsorbents

ACCEPTED MANUSCRIPT

Table 9: Comparison of different adsorbent with present study for removal of arsenic and fluoride from water Adsorbent

Maximum adsorption capacity mg/g

pH

Reference

Gibbsite

0.073

3.0–7.0

140

Fly ash

0.40

Hematite

0.003

Feldspar

0.003

Iron oxide coated sand

0.01

RH-FeOOH

0.03

Blue Pine wood shavings

0.1

Quaternized rice husks

0.77

Activated alumina

0.18

RI PT

Arsenic

141

4.2

141

6.2

141

4

142

4

143

10

55

7-8

144

7-8

144

1.92

7

Present study

0.04

8

Present study

0.02

7

Present study

0.42

4.5

120

1.76

6

145

1.16

-

-

0.39

6

145

0.26

6

146

Crassipes biomassand itscarbonized form

0.52

5.5

147

Geogenicapatite

0.01

5-6

148

Fe–Al–Cenanoadsorbent

2.22

7

149

Calciumchloridemodified natural zeolite Hydrated Cement

1.76

6

150

1.72

7

Present study

Bricks Powder

0.84

8

Present study

Marble Powder

0.18

7

Present study

M AN U

Hydrated Cement Bricks Powder Marble Powder Fluoride Al(OH)coated ricehusks ash

TE D

Fluorspar Activated quartz Calcite

AC C

EP

Montmorillonite

SC

4.0

ACCEPTED MANUSCRIPT

Figure 1: Effect of contact time on adsorption of arsenic and fluoride (a) Hydrated Cement (b) Marble powder (c) Bricks powder

100

HC

60

As

40

SC

% Removal

80

RI PT

A

F

20

100

MP

TE D

% Removal

60

20

90

B

80

40

60 Time (min)

M AN U

30

EP

30

60 Time (min)

90

AC C

100

BP

C

%Removal

80

60

40

20 30

60 Time (min)

90

ACCEPTED MANUSCRIPT

% Removal

110

HC

90

As

70

F

RI PT

Figure 2: Effect of adsorbent dose on adsorption of arsenic and fluoride (a) Hydrated Cement (b) Marble powder (c) Bricks powder

SC

A

50

10

20

30

40

90

MP

70

TE D

% Removal

110

M AN U

Adsorbent dose (g/l)

B

50

10

20

30

40

EP

Adsorbent dose (g/l)

PB

% Removal

AC C

110

90

70

C 50 10

20

30

Adsorbent dose (g/l)

40

ACCEPTED MANUSCRIPT

Figure 3: Effect of pH on adsorption of arsenic and fluoride (a) Hydrated Cement (b) Marble powder (c) Bricks powder

110

% Removal

90

70 As

2

3

4

5

6

110

90

70

8

9

B

TE D

% Removal

MP

7

M AN U

pH

SC

F

50

RI PT

A

HC

50

3

4

5

6

7

8

9

pH

EP

2

110

% Removal

AC C

BP

C

90

70

50 2

3

4

5

6 pH

7

8

9

ACCEPTED MANUSCRIPT

Figure 4: Effect of adsorbate concentration on adsorption of arsenic and fluoride (a) Hydrated Cement (b) Marble powder (c) Bricks Powder

110

HC

90

RI PT

% Removal

100

80 70

As

60 F

A 100

500 Adsorbate Conc.

1000

M AN U

100

SC

50

MP

% Removal

90 80 70

TE D

60

B

50

100

500

1000

Adsorbate Conc.

EP

110

BP

AC C

% Removal

100 90 80 70 60

C 50 100

500 1000 Adsorbate Conc.

ACCEPTED MANUSCRIPT

Figure 5: Langmuir Isotherm (5A) Arsenic (5B) Fluoride 10.0

400

MP

MP

8.0 6.0

1/qe

200

4.0

100

2.0

RI PT

1/qe

300

0.0

0 0

100

200

0.0

300

1.0

1/C 400

HC

10.0

3.0

4.0

8.0

200

6.0

SC

300

1/qe

1/qe

HC

4.0

100

M AN U

2.0 0

0.0

0

500

1000

1/C

400

0.0

10.0

BP

5.0

10.0

15.0

20.0

25.0

1/C

BP

8.0

1/qe

300 200

TE D

1/qe

2.0

1/C

100 0 0

100

200

1/C

AC C

EP

5(a)

300

6.0 4.0 2.0 0.0

0.0

0.5

1.0

1/C

5(b)

1.5

2.0

ACCEPTED MANUSCRIPT

Figure 6: Freundlich Isotherm (6a) As (F-)

8

8.0

MP

MP 6.0

4

RI PT

Log qe

Log qe

6

4.0 2.0

2

0.0

0 0

2

4

6

-3.0

-2.0

-1.0

HC

2

M AN U

Log qe

6.0

4

4.0 2.0

0 0

2

4

6

8

TE D

Log C

BP

6 4

2

Log C

AC C

0

EP

2 0

8

4

0.0

-4.0

-2.0

0.0

2.0

4.0

Log C

8.0 BP 6.0

Log qe

Log qe

2.0

8.0

HC

6

Log qe

1.0

SC

8

0.0

Log C

Log C

4.0 2.0 0.0

6

-2.5

-2.0

-1.5

-1.0

-0.5

Log C

0.0

0.5

1.0

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

Figure 7a. XRD spectra of Marble Powder

Figure 7b. XRD spectra of Bricks Powder

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

Figure 7c: XRD spectra of Hydrated Cement

ACCEPTED MANUSCRIPT

Figure 8: SEM of Marble Powder (8a) unloaded (8b) lorded (8c) high resolution SEM of single pore shown in 8a

M AN U

SC

RI PT

8a

4c

AC C

8c

EP

TE D

8b

ACCEPTED MANUSCRIPT

Figure 9: SEM of Hydrated Cement (9a) unloaded (9b) loaded (9c) high resolution SEM of single pore shown in 9a

M AN U

SC

RI PT

9a

AC C

9c

EP

TE D

9b

ACCEPTED MANUSCRIPT

Figure 10: SEM of Bricks powder (10a) unloaded (10b) loaded (10c) high resolution SEM of single pore shown in 10a

M AN U

SC

RI PT

10a

AC C

EP

TE D

10b

10c cc

ACCEPTED MANUSCRIPT

Highlights (for review) Simultaneous removal of arsenic and fluoride from drinking water.



Industrial waste materials used for the removal of arsenic and fluoride.



Hydrated Cement, Marble Powder and Bricks Powder are efficient and cost effective adsorbents.

RI PT





XRD and SEM were performed to assess the surface morphology of adsorbents.



Hydrated Cement, Marble Powder and Bricks Powder used first time for the

AC C

EP

TE D

M AN U

SC

simultaneous removal of arsenic and fluoride.