Contribution of H-bond in adsorptive removal of pharmaceutical and personal care products from water using oxidized activated carbon

Accepted Manuscript Contribution of H-bond in adsorptive removal of pharmaceutical and personal care products from water using oxidized activated carbon Ji Yoon Song, Biswa Nath Bhadra, Sung Hwa Jhung PII:

S1387-1811(17)30079-3

DOI:

10.1016/j.micromeso.2017.02.024

Reference:

MICMAT 8134

To appear in:

Microporous and Mesoporous Materials

Received Date: 14 November 2016 Revised Date:

24 January 2017

Accepted Date: 9 February 2017

Please cite this article as: J.Y. Song, B.N. Bhadra, S.H. Jhung, Contribution of H-bond in adsorptive removal of pharmaceutical and personal care products from water using oxidized activated carbon, Microporous and Mesoporous Materials (2017), doi: 10.1016/j.micromeso.2017.02.024. 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.

ACCEPTED MANUSCRIPT Graphical Abstract:

Adsorptive Removal of PPCPs over OACs NH2

H-bond O

Cl

O

O

O

HO

Cl

O Cl

OH

O

O

O H

H

H

NH

H

O

Oxidized Activated Carbons

O

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Oxidized Activated Carbons

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Contribution of H-bond in adsorptive removal of pharmaceutical and personal care products from water using oxidized activated carbon

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Ji Yoon Song, Biswa Nath Bhadra, and Sung Hwa Jhung*

Department of Chemistry and Green-Nano Materials Research Center, Kyungpook

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National University, Daegu 41566, Republic of Korea

*Corresponding Author: Prof. Sung Hwa Jhung Fax: 82-53-950-6330

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E-mail: [email protected]

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Abstract Adsorption of four pharmaceuticals and personal care products (PPCPs) by activated carbon (AC) before and after oxidative modification with ammonium persulfate (APS) at

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different concentrations was studied. The PPCPs were selected to exhibit a wide range of acid-base characteristics, i.e., basic atenolol, neutral N,N-diethyl-meta-toluamide, weakly acidic triclosan, and acidic naproxen. The oxidized ACs (OACs) showed highly

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improved adsorption of the PPCPs compared with that of the pristine AC, irrespective of the acid-base properties of the PPCPs. For example, the best OAC adsorbed 93, 55, 89,

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80 mg/g of atenolol, N,N-diethyl-meta-toluamide, triclosan, and naproxen, respectively, from water in 12 h; however, pristine AC adsorbed only 33, 39, 60, 39 mg/g, respectively. The adsorption mechanism was explained in terms of H-bonding and a partial contribution by electrostatic and π-π interactions through analyses of the adsorptive

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performances and surface charges of the OACs over a wide range of pH conditions. Especially, the direction of H-bond could be clearly explained (H-acceptor: PPCPs; Hdonor: OACs). OACs are a promising adsorbent for PPCPs over a wide acidity/basicity

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range owing to their high adsorption capacity and facile reusability.

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Keywords: acid-base property; adsorption; H-bond; porous activated carbon; PPCPs

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1. Introduction The contamination of surface and ground water is becoming an increasingly serious problem worldwide owing to improving living standards and growing populations.

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Pharmaceuticals and personal care products (PPCPs) are one of the main contributors to water contamination because of their necessity in everyday life and huge worldwide production and consumption [1–9]. PPCPs may remain in the environment even after

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they have been used [1–9] as they usually have long shelf lives and are often inadvertently dumped into the environment. Consequently, PPCPs have recently been

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found in a number of water resources and even in the tissues of fish and vegetables [1– 13], and are therefore regarded as emerging contaminants [7-9]. It is reported that PPCPs may cause endocrine disruptions that can change hormonal actions [1–13]; therefore, the removal of PPCPs from aquatic systems is becoming increasingly important [1–15], even

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though PPCP levels in the environment are not currently explicitly regulated. Several methods have been applied for the removal of PPCPs from the environment, including chlorination, advanced oxidation processes (AOPs)/ozonation, coagulation–

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flocculation, photodegradation, and biodegradation [1–17]. However, these technologies

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are not sufficiently successful and require more research and improvement. For example, AOPs and ozonation have the disadvantages of high energy consumption and the formation of residual byproducts [16, 17], respectively. Adsorption is a potentially attractive method for the removal of PPCPs from water

owing to its low energy consumption, mild operation conditions, and low production of harmful side products. To date, carbonaceous materials including activated carbons (ACs), carbon nanotubes, and graphene [3, 18], and transition metal-grafted mesoporous 3

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materials [14, 15] have been widely studied as potential adsorbents for the removal of PPCPs. ACs are widely used porous materials for various adsorption applications because of

to

control

their

functional

groups

and

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their low cost, large pore size, and high porosity. Moreover, ACs can be modified easily hydrophobicity/hydrophilicity

via

oxidation/reduction reactions and acid/base treatments [19–22]. Oxidation is a

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particularly well developed method to introduce acidic or basic functional groups to the surface of carbonaceous materials, including ACs [23–25]. More importantly, oxidized

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carbonaceous materials are useful adsorbents in the fuel industry, where they are used for adsorptive desulfurization and denitrogenation [20-22, 24, 26], and water purification [27–29], because of their oxygen-containing functional groups.

Recently, we reported the preparation of oxidized ACs (OACs) by treating ACs with

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solutions of sulfuric acid and ammonium persulfate (APS) at different APS concentrations. Moreover, the application of OACs to the adsorptive removal of diclofenac sodium, a typical PPCP, was suggested [30]. In the present study, we have

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applied OACs to the adsorptive removal of PPCPs with different acidity/basicity characteristics in order to explore the possible application of OACs to the adsorptive

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removal of various PPCPs from water. Especially, adsorption mechanisms, including Hbond, were explained based on the adsorptions of the four PPCPs in wide conditions. Atenolol (ATL), N,N-diethyl-meta-toluamide (DEET), triclosan (TCS), and naproxen (NPX) were used in this study to represent basic, neutral, weakly acidic, and acidic PPCPs, respectively.

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ATL, DEET, TCS, and NPX are a typical β–blocker [31–34], insect repellant [37–39], antibacterial/antifungal agent [40–50] and nonsteroidal anti-inflammatory drug [51–57], respectively. The adsorptive removal of ATL, DEET, TCS, and NPX from water has been

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studied recently, since such PPCPs are widely used, might be hazardous to aquatic lives and mankind (even if contacted inadvertently) and often found in water resources. The chemical structures and physical properties of these PPCPs are shown in Scheme 1 and

2.1 Chemicals

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2. Materials and methods

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Table 1, respectively.

ATL (98%), DEET (97%), and NPX (98%) were obtained from Sigma Aldrich. TCS (99%) was bought from Alfa Aesar. Granular AC (2–3 mm, practical grade) was

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purchased from Duksan Pure Chemical Co., Ltd. Sulfuric acid (98%) and hydrochloric acid (36%) were acquired from OCI Chemicals, and APS ((NH4)2S2O8, 98%), sodium hydroxide (98%), sodium carbonate (Na2CO3, 98%), and sodium bicarbonate (NaHCO3,

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98%) were obtained from Daejung Chemicals and Metals Ltd. All chemicals were of

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analytical grade and used without further purification.

2.2 Preparation of OACs Modification of the commercial AC to OACs was carried out following the method of

Li et al. [23] using a solution of ammonium persulfate (APS) and sulfuric acid. The OACs were designated OAC(0.5), OAC(1.0), OAC(1.5), OAC(2.0), and OAC(2.5), where the number in parentheses denotes the molar concentration of APS in the solution 5

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used for oxidation. Details of the method for oxidation to produce OACs are given in a previous report [30].

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2.3 Characterization of AC and OACs

The contents of C, H, and O of the AC and OACs were measured with a chemical analysis (Thermo Fisher, Flash2000 with thermal conductivity detector). In order to

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analyze the contents of inorganic species such as Al, Fe and Si in the AC and OACs, ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometer) (Thermo

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Scientific Co./iCAP 6300 Duo) was applied. The surface areas of the carbonaceous materials were measured at -196 °C by nitrogen adsorption with a surface area and porosity analyzer (Tristar II 3020, Micromeritics, USA). All of the adsorbents were evacuated at 150 °C for 12 h before nitrogen adsorption. The Brunauer-Emmett-Teller

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(BET) method was applied to estimate the surface area. Quantification of the surface functional groups was carried out using Boehm titration [20]. The OAC (500 mg) for analysis was added to each of three separate beakers containing NaOH, Na2CO3, or

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NaHCO3 (50 mL, 0.10 M each), and the mixtures were stirred magnetically for 24 h at 25 °C. After neutralization, the liquid portions were collected by filtration, and the

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concentration of acidic functional groups was calculated by titration of the obtained solutions with standard aqueous HCl (0.10 M) solution using methyl orange as the indicator. The zeta potential of OAC(2.0) was measured at various pH values using a Zetasizer Nano zs90 instrument. FTIR spectroscopic analyses were carried out with a Jasco FTIR-4100 using attenuated total reflectance and a maximum resolution of 0.9 cm-1.

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2.4 Adsorption experiments PPCP solutions for adsorption experiments were prepared from a stock solution of each PPCP (500 mg·L-1) in water/methanol (90/10 v/v). Solutions with the desired

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concentrations (25 to 100 mg·L-1) were prepared by successive dilution of the stock solution with deionized water. The pH of each solution was maintained at 6.0 ± 1.0, considering the pH of rain and river water (summarized in Supporting Table S1). The pH

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of the ATL solution was maintained at 6.0 by adding a small amount of 0.1 M HCl solution to the original aqueous ATL solution having a pH of 8.5. DEET (pH 6.7), TCS

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(pH 5.6), and NPX (pH 5.2) aqueous solutions were prepared by simple dissolution (without adding acid or base to control pH) of the PPCPs stock solutions with deionized water.

The adsorbents were dried overnight at 100 °C in a vacuum oven and used for

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adsorption of PPCPs from water. The adsorbent (5.0 mg) was added to the PPCP solution (25 mL) and the mixture was shaken using an incubator shaker at a constant speed (250 rpm) at 25 °C for a set time. After finishing adsorption, the solution was collected by

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filtration with a syringe filter (polytetrafluoroethylene, hydrophobic, 0.5 µm), and the residual concentration of the PPCP was evaluated by UV spectrometry (UV-1800,

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Shimadzu, Japan). The absorbances at 224, 270, 277, and 262 nm were used to estimate the concentrations of ATL, DEET, TCS, and NPX, respectively. All of the adsorption experiments were performed three times to acquire average values, which are reported here. Langmuir isotherms [58] were applied to investigate the adsorption results. The calculation methods are described in detail in the Supporting Information.

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To determine the effect of solution pH on the amount of PPCP adsorbed (qt) on OAC(2.0), the pH of the PPCP solution (50 mg·L-1) was altered with either aqueous HCl (0.10 M) or NaOH (0.10 M) solution. The reusability of OAC(2.0) was evaluated after

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the adsorption of ATL for 12 h. OAC(2.0) (50 mg), after ATL adsorption, was separated by filtration and washed with deionized water, and then placed into acetone (20 mL) and soaked for 12 h at 25 °C. The soaking was repeated three times to completely remove the

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adsorbed ATL. The details of the reusability tests are described in the Supporting

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Results and discussion

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Information.

3.1 Physicochemical properties of AC and OACs

The chemical and ICP analysis results of AC and OACs (summarized in Supporting

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Table S2) show that concentrations of H and O increased monotonously with increasing the APS concentration in the solution for the oxidation of AC; however, the content of C decreased accordingly with the APS concentration for oxidation. The contents of Al, Fe,

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and Si in the carbonaceous materials were relatively low and did not change remarkably with the APS concentration, suggesting that the oxidation using APS and sulfuric acid

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does not have any remarkable influence on the concentration of inorganic impurities in the carbons. The BET surface areas (presented in Table S3) of AC and OACs show that the porosity of carbons was decreased slightly with increasing APS concentration in the oxidation; therefore, too harsh oxidation might be not helpful for adsorptions. The concentrations (shown in Table S3) of acidic functional groups of AC and OACs, determined by Boehm titration, show that the oxidation in high APS concentration

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generally increases the total and phenolic acid concentrations up to a certain APS concentration (2 M). The content of carboxylic acid of carbons increased monotonously with the concentration of APS in the oxidation; however, the content of lactonic acid is

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relatively low and the concentration of APS does not have clear influence on the concentration of lactonic acid. The decrease in the concentration of total and phenolic acids with increasing APS concentration above 2 M might be because of further

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oxidation of such acids into carboxylic or lactonic acid (or destruction of carbon structure

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because of very harsh condition).

3.2 Relative adsorption capacities of the adsorbents for ATL

ATL adsorption was performed for 12 h over the OACs and the AC in order to compare the relative performances of the adsorbents. As shown in Fig. 1, the amounts of

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adsorbed ATL after 12 h (q12 h) decrease in the order OAC(2.0) > OAC(1.5) > OAC(1.0) ~ OAC(2.5) > OAC(0.5) > AC. This tendency is not easy to understand if the surface areas (Table S3) of the adsorbents are the only important parameter in the adsorptions. In

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the absence of a special adsorption mechanism, the performances of adsorbents usually depend on their surface area [51, 59] owing to van der Waals interactions. Pore structures

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[60, 61] might be also considered to understand the adsorption of ATL over AC and OACs; however, those might be not very important in this study considering the very similar nitrogen adsorption isotherms of the OACs and AC [30]. Adsorption of ATL was further performed over different times using three

representative adsorbents (AC, OAC(1.0), and OAC(2.0)). As shown in Fig. 2, the general trend for adsorbed amount (qt) of ATL is in agreement with that in Fig. 1, and the

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relative performances of the three adsorbents do not depend on the adsorption times from 30 min to 12 h. Moreover, the adsorptions are usually completed in 4 h irrespective of oxidative modification of AC. Generally, it can be concluded that OAC(2.0) is superior to

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the pristine AC in the adsorptive removal of ATL under all adsorption conditions; therefore, all further experiments were performed with OAC(2.0) and AC.

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3.3 Adsorption isotherms

The adsorption of ATL was performed for sufficiently long time of 12 h over AC and

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OAC(2.0) in order to obtain the adsorption isotherms shown in Fig. 3a. The maximum adsorption capacities (Q0) calculated from Langmuir plots (Fig. 3b), which were obtained from the isotherms, are summarized in Table 2. It can be confirmed that the adsorptive performance of AC for ATL is increased by 1.6 times by oxidation with APS under

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suitable conditions (i.e., the Q0 of OAC(2.0) is 2.6 times that of pristine AC). Additionally, as illustrated in Table S4, OAC(2.0) showed the highest Q0 for ATL among the reported results, showing the competitiveness of OAC(2.0) in adsorptive removal of

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ATL from water. Moreover, another Langmuir parameter (b-value) also reflects the beneficial effect of oxidative modification of AC for adsorption of ATL. Therefore, it can

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be assumed that conventional ACs, especially after adequate oxidative modifications, can be effectively utilized for ATL adsorption.

3.4 Adsorption of other PPCPs Adsorption of other PPCPs (i.e., the neutral or acidic species) was carried out using AC and OAC(2.0) in order to confirm the beneficial role of oxidation in enhancing the

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adsorptive performances of conventional AC. As shown in Fig. 4, the amounts of PPCPs adsorbed (30 min – 12 h) including ATL increase after oxidative modification of AC, confirming the beneficial effect of the oxidation of AC upon adsorption of PPCPs,

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irrespective of their acidity or basicity. However, as shown in Table 3, the degree of increase in qt depends on the adsorbate. The ratio qtOAC(2.0)/qtAC decreases in the order ATL > NPX > TCS > DEET both at 4 h and 12 h. The degree of increase in qt by

KOW, pKa, and solubility in water, shown in Table 1.

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oxidation of AC cannot be explained by any property of the PPCPs, such as molar mass,

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Therefore, the functional groups (summarized in Table 1 and Scheme 1) of PPCPs were considered in order to rationalize this observation, since there are several mechanisms to explain adsorption in the liquid phase [3, 28, 62–65]. Considering the functional groups present on the OACs, such as phenol and carboxylic acid (shown in

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Table S3), the functional groups of the PPCPs were counted (Table 3) to assess their ability to form H-bonds with the adsorbents. The values for qtOAC(2.0)/qtAC are in general agreement with the number of H-bond acceptors on the PPCPs, but there is no

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relationship between qtOAC(2.0)/qtAC and the number of H-bond donors on the PPCPs. Therefore, it can be assumed that H-bonding (see section 3.4 for more a detailed

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discussion on H-bonding) between the PPCPs (the H-acceptor) and the OACs (the Hdonor) is important for the adsorption of PPCPs by OACs, similarly to the H-bond formation between diclofenac and OAC [30]. In the case of TCS, the qtOAC(2.0)/qtAC ratio is 1.5 for both 4 h and 12 h, and is not much higher than that for DEET (1.4), even though the number of H-bond acceptors is 2 and 1 for TCS and DEET, respectively. This

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relatively low ratio in the case of TCS might be explained by the two benzene rings in

3.5 Effect of pH on adsorption and mechanism of adsorption

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TCS, which may allow adsorption via π–π interaction [66] onto the untreated AC.

The pH of the PPCP solution has a significant impact on adsorption since the protonation/deprotonation of the PPCPs and the surface charge of the adsorbents depend

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on pH [30, 52, 53, 62, 67]. Consequently, the quantities of the four PPCPs adsorbed at 12 h (q12 h) over OAC(2.0) were measured under various pH conditions. As shown in Fig. 5,

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q12 h generally decreases with increasing pH for DEET, TCS, and NPX; however, q12 h for ATL increases with increasing pH (up to ca. 8.5), peaks, and then decreases upon further increase in pH. The tendency for DEET, TCS and NPX might be considered firstly with the idea of electrostatic interaction (common mechanism for PPCPs adsorption [32, 34,

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47, 52, 62]) utilizing surface charge of OAC(2.0), measured by zeta potential (Fig. S1). However, the electrostatic interaction mechanism should be discarded for the adsorption of DEET, TCS, and NPX. The relatively high adsorption of DEET, TCS and

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NPX especially at low pH cannot be explained with electrostatic interaction because positive charge will be negligibly developed on the PPCPs at low pH. Especially, the

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effect of pH on DEET adsorption cannot be explained by electrostatic interactions, since the charge on DEET barely changes with pH. If we consider a partial positive charge on the N of DEET (owing to resonance), the q12

h

of DEET might be increased with

increasing pH based on the increasing negative charge on OAC(2.0) with increasing pH (Fig. S1). However, the q12 h over OAC(2.0) decreased with increasing pH, contrary to this expectation.

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Therefore, other mechanisms are needed to explain the adsorption of the three PPCPs over the wide pH range investigated. H-bonding may be the main driving force for DEET adsorption over OAC(2.0), especially at low pH, based on the presence of carboxylic and

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phenolic groups on OAC(2.0). The H atom of the carboxylic acid or phenol group of OAC(2.0), which can be used for H donation, will be important for DEET adsorption via H-bonding considering the absence of any H in DEET suitable as an H-donor. With

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increasing pH, the H-donor content of OAC(2.0) will be decreased because of deprotonation; therefore the effect of pH on q12h for DEET may be explained. On the

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other hand, the negligible adsorption at pH > 10 is expected considering the deprotonation of phenol and carboxylic groups of OAC(2.0). However, a small amount of adsorption is observed even at high pH values sufficient for full deprotonation of OAC(2.0). This appreciable adsorption of DEET may be explained by electrostatic

OAC(2.0).

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interaction between the partially positive N of DEET and the negative surface of

Similarly, H-bonding may be the main mechanism for the adsorption of TCS and

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NPX over OAC(2.0), considering the electronegative O in TCS and NPX, and the functional groups (–COOH and/or –OH) on OAC(2.0). Especially, the high q12 h values

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for TCS and NPX at lower pH can be explained by the H-bond considering the free phenol or carboxylic acid group on the adsorbent. The decreasing q12 h with increasing pH can be explained by successive deprotonation leading to repulsion from the negative surface of the OAC(2.0). The appreciable q12 h for NPX at pH 10–12 might be explained by π–π interaction, which is a common adsorption mechanism over ACs [3, 18, 40].

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The effect of pH on the adsorption of basic ATL is very different to that for the other three PPCPs. Decreasing q12 h with decreasing pH from 8 to 2 may be explained firstly by the

decreased

electrostatic

interaction

(between

negative

OAC(2.0)

and

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positive/protonated ATL) considering the decreasing negative surface charge (Fig. S1) of the adsorbent with decreasing pH. However, the considerable q12 h at pH ca. 2.0 cannot be explained by only electrostatic interactions, since OAC(2.0) has a nearly neutral surface h

with increasing pH from 8 to 12 might be

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charge at that pH. The decrease in q12

explained by also the decreased electrostatic interaction (due to the neutrality of ATL at

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pH > 9.6). However, very sharp decrease of q12 h with increasing pH above 9.6 cannot be explained simply with electrostatic interaction considering the neutral ATL with nearly constant charge density (even with changing pH). In the ATL adsorption, similar to other PPCPs, therefore, the contribution of H-bonding should also be considered based on the

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functional groups (phenolic and carboxylic acid) of OAC(2.0) and the existence of 3 or 4 O or N sites that can be used as H-acceptors for H-bonds. The contribution of H-bonding to the ATL adsorption might also be important at pH < 10 where the free phenol group h

of ATL at pH > 10 might be explained with

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can be maintained. The small q12

electrostatic interaction between negative OAC(2.0) and partially positive charge on the

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N (of the amide group).

As described in section 3.3, the ratios qtOAC(2.0)/qtAC shown in Table 3 also support

the importance of the contribution of H-bonding to the adsorption of the four PPCPs. Therefore, the mechanism of adsorption can be explained by H-bonding (importantly, Hacceptor from PPCPs and H-donor from OACs) combined with a partial contribution by electrostatic interaction (especially for ATL and DEET) or π–π interaction (for NPX).

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This H-bonding mechanism, which is shown as Scheme 2, has been applied recently to rationalize not only adsorptions in aqueous solutions [18, 30, 40, 47, 62, 63, 68-72] but

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also fuel purification [72–76].

3.6 Reusability of OAC(2.0)

The reusability of adsorbents is very important for commercial applications

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considering the possible reduction of adsorbents cost via uses in several times. The reusability of OAC(2.0) was checked for ATL adsorption over five runs by washing the

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used adsorbent with acetone. As shown in Fig. 6, OAC(2.0) is reusable for ATL adsorption, even though the performance decreases slightly with the number of runs. The slight decrease in the performance might be because of a strong interaction between acidic OAC(2.0) and basic ATL. Importantly, q12 h for OAC(2.0) even after the fifth run

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is still much higher than that for fresh AC (as shown by the vertical line in Fig. 6). The adsorbent OAC(2.0)s (fresh, used for ATL adsorption and recycled ones) were also analyzed with FTIR together with adsorbate ATL itself. As shown in Fig. 7, the FTIR of

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the used sample confirms the presence of ATL in the adsorbent, and the FTIR spectra of the washed OAC(2.0) are very similar to that of the fresh adsorbent, indicating the

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successful removal of adsorbed ATL, which is in agreement with the results of the recycling tests shown in Fig. 6.

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Conclusions

The adsorption of four PPCPs with different acid-base properties over OACs was investigated, leading to the following conclusions. First, the OACs are highly effective in

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adsorbing different PPCPs owing to the introduction of acidic functional groups, such as phenol and carboxylic acid, by oxidative modification of AC. Second, H-bonding is the main mechanism for the adsorption of PPCPs, even though electrostatic interactions and

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π–π interactions partly contribute to the adsorption of the PPCPs. Third, the direction of H-bond could be clearly suggested (H-acceptor: adsorbates or PPCPs; H-donor: adsorbents or OACs). Fourth, OACs are suitable as competitive adsorbents for different

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PPCPs owing to their high capacity and ready recyclability.

Acknowledgement

This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT

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and future Planning (grant number: 2015R1A2A1A15055291).

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References [1] D.N. Bulloch, E.D. Nelson, S.A. Carr, C.R. Wissman, J.L. Armstrong, D. Schlenk, C.K. Larive, Occurrence of halogenated transformation products of selected pharmaceuticals and personal care products in secondary and tertiary treated wastewaters from Southern California, Environ. Sci. Technol. 49 (2015) 2044-2051.

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[2] Q. Bu, B. Wang, J. Huang, S. Deng, G. Yu, Pharmaceuticals and personal care products in the aquatic environment in China: a review, J. Hazard. Mater. 262 (2013) 189-211. [3] C. Jung, A. Son, N. Her, K.D. Zoh, J. Cho, Y. Yoon, Removal of endocrine disrupting compounds, pharmaceuticals, and personal care products in water using carbon nanotubes: a review, J. Ind. Eng. Chem. 27 (2015) 1-11.

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[4] S. Dong, J. Feng, M. Fan, Y. Pi, L. Hu, X. Han, M. Liu, J. Sun, J. Sun, Recent developments in heterogeneous photocatalytic water treatment using visible light-responsive photocatalysts: a review, RSC Adv. 5 (2015) 14610-14630.

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[5] X. Yang, R.C. Flowers, H.S. Weinberg, P.C. Singer, Occurrence and removal of pharmaceuticals and personal care products (PPCPs) in an advanced wastewater reclamation plant, Water Res. 45 (2011) 5218-5228. [6] P. Westerhoff, Y. Yoon, S. Snyder, E. Wert, Fate of endocrine-disruptor, pharmaceutical, and personal care product chemicals during simulated drinking water treatment processes, Environ. Sci. Technol. 39 (2005) 6649-6663. [7] N. Bolong, A.F. Ismail, M.R. Salim, T. Matsuura, A review of the effects of emerging contaminants in wastewater and options for their removal, Desalination 239 (2009) 229–246.

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[8] S.D. Richardson, T.A. Ternes, Water analysis: emerging contaminants and current issues, Anal. Chem. 86 (2014) 2813-2848. [9] C. Gadipelly, A. Pérez-González, G.D. Yadav, I. Ortiz, R. Ibáñez, V.K. Rathod, K.V. Marathe, Pharmaceutical industry wastewater: review of the technologies for water treatment and reuse, Ind. Eng. Chem. Res. 53 (2014) 11571-11592.

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[10] X. Wu, J.L. Conkle, F. Ernst, J. Gan, Treated wastewater irrigation: uptake of pharmaceutical and personal care products by common vegetables under field conditions, Environ. Sci. Technol. 48 (2014) 11286-11293.

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[11] E.L. Miller, S.L. Nason, K.G. Karthikeyan, J.A. Pederse, Root uptake of pharmaceutical and personal care product ingredients, Environ. Sci. Technol. 50 (2016) 525-541. [12] R. Tanoue, K. Nomiyama, H. Nakamura, J.W. Kim, T. Isobe, R. Shinohara, T. Kunisue, S. Tanabe, Uptake and tissue distribution of pharmaceuticals and personal care products in wild fish from treatedwastewater-impacted streams, Environ. Sci. Technol. 49 (2015) 11649-11658. [13] B. Subedi, B. Du, C.K. Chambliss, J. Koschorreck, H. Rüdel, M. Quack, B.W. Brooks, S. Usenko, Occurrence of pharmaceuticals and personal care products in German fish tissue: a national study, Environ. Sci. Technol. 46 (2012) 9047-9054. [14] S.M. Rivera-Jiménez, S. Méndez-González, A. Hernández-Maldonado, Metal (M = Co2+, Ni2+, and Cu2+) grafted mesoporous SBA-15: Effect of transition metal incorporation and pH conditions on the adsorption of Naproxen from water, Micropor. Mesopor. Mater. 132 (2010) 470-479.

17

ACCEPTED MANUSCRIPT

[15] S.M. Rivera-Jiménez, A.J. Hernández-Maldonado, Nickel (II) grafted MCM-41: A novel sorbent for the removal of naproxen from water, Micropor. Mesopor. Mater. 116 (2008) 246-252. [16] M. Klavarioti, D. Mantzavinos, D. Kassinos, Removal of residual pharmaceuticals from aqueous systems by advanced oxidation processes, Environ. Int. 35 (2009) 402-417.

RI PT

[17] S. Esplugas, D.M. Bila, L.G.T. Krause, M. Dezotti, Ozonation and advanced oxidation technologies to remove endocrine disrupting chemicals (EDCs) and pharmaceuticals and personal care products (PPCPs) in water effluents, J. Hazard. Mater. 149 (2007) 631-642. [18] H.E. Reynel-Avila, D.I. Mendoza-Castillo, A. Bonilla-Petriciolet, J. Silvestre-Albero, Assessment of naproxen adsorption on bone char in aqueous solutions using batch and fixed-bed processes, J. Mol. Liq. 209 (2015) 187-195.

SC

[19] X. Feng, X. Ma, N. Li, C. Shang, X. Yang, X.D. Chen, Adsorption of quinoline from liquid hydrocarbons on graphite oxide and activated carbons, RSC Adv. 5 (2015) 74684–74691.

M AN U

[20] B.K. Jung, S.H. Jhung, Adsorptive removal of benzothiophene from model fuel, using modified activated carbons, in presence of diethylether, Fuel 145 (2015) 249–255. [21] X. Han, H. Lin, Y. Zheng, Adsorptive denitrogenation and desulfurization of diesel using activated carbons oxidized by (NH4)2S2O8 under mild conditions, Can. J. Chem. Eng. 93 (2015) 538-548. [22] X. Han, H. Lin, Y. Zheng, The role of oxygen functional groups in the adsorption of heteroaromatic nitrogen compounds, J. Hazard. Mater. 297 (2015) 217–223. [23] N. Li, X. Ma, Q. Zha, K. Kim, Y. Chen, C. Song, Maximizing the number of oxygen-containing functional groups on activated carbon by using ammonium persulfate and improving the temperatureprogrammed desorption characterization of carbon surface chemistry, Carbon 49 (2011) 5002 –5013.

TE D

[24] N. Li, J. Zhu, X. Ma, Q. Zha, C. Song, Tailoring of surface oxygen-containing functional groups and their effect on adsorptive denitrogenation of liquid hydrocarbons over activated carbon, AIChE J. 59 (2013) 1236–1244. [25] J. Shen, Y. Hu, M. Shi, X. Lu, C. Qin, C. Li, M. Ye, Fast and facile preparation of graphene oxide and reduced grapheme oxide nanoplatelets, Chem. Mater. 21 (2009) 3514–3520.

EP

[26] X. Ren, C. Chen, M. Nagatsu, X. Wang, Carbon nanotubes as adsorbents in environmental pollution management: a review, Chem. Eng. J. 170 (2011) 395–410.

AC C

[27] N. L. Torad, M. Hu, S. Ishihara, H. Sukegawa, A. A. Belik, M. Imura, K. Ariga, Y. Sakka, Y. Yamauchi, Direct Synthesis of MOF-Derived Nanoporous Carbon with Magnetic Co Nanoparticles toward Efficient Water Treatment, Small 10 (2014) 2096–2107. [28] X. Li, J.J. Pignatello, Y. Wang, B.S. Xing, New insight into adsorption mechanism of ionizable compounds on carbon nanotubes, Environ. Sci. Technol. 47 (2013) 8334–8341. [29] A. Carmalin Sophia, E.C. Lima, N. Allaudeen, S. Rajan, Application of graphene based materials for adsorption of pharmaceutical traces from water and wastewater-a review, Desalin. Water Treat. 57 (2016) 1-14. [30] B.N. Bhadra, P.W. Seo, S.H. Jhung, Adsorption of diclofenac sodium from water using oxidized activated carbon, Chem. Eng. J. 301 (2016) 27-34.

18

ACCEPTED MANUSCRIPT

[31] V. Rakić, V. Rac, M. Krmar, O. Otman, A. Auroux, The adsorption of pharmaceutically active compounds from aqueous solutions onto activated carbons, J. Hazard. Mater. 282 (2015) 141-149. [32] L.F. Delgado, P. Charles, K. Glucina, C. Morlay, Adsorption of ibuprofen and atenolol at trace concentration on activated carbon, Sep. Sci. Technol. 50 (2015) 1487-1496.

RI PT

[33] V. Rakić, N. Rajić, A. Daković, A. Auroux, The adsorption of salicylic acid, acetylsalicylic acid and atenolol from aqueous solutions onto natural zeolites and clays: Clinoptilolite, bentonite and kaolin, Micropor. Mesopor. Mater. 166 (2013) 185-194. [34] L. Pasti, E. Sarti, A. Cavazzini, N. Marchetti, F. Dondi, A. Martucci, Factors affecting drug adsorption on beta zeolites, J. Sep. Sci. 36 (2013) 1604-1611.

SC

[35] J.L. Sotelo, G. Ovejero, A. Rodríguez, S. Álvarez, J. García, Removal of atenolol and isoproturon in aqueous solutions by adsorption in a fixed-bed column, Ind. Eng. Chem. Res. 51 (2012) 5045-5055.

M AN U

[36] J.L. Sotelo, A.R. Rodríguez, M.M. Mateos, S.D. Hernández, S.A. Torrellas, J.G. Rodríguez, Adsorption of pharmaceutical compounds and an endocrine disruptor from aqueous solutions by carbon materials, J. Environ. Sci. Health B 47 (2012) 640-652. [37] A. Trouvé, I. Batonneau-Gener, S. Valange, M. Bonne, S. Mignard, Tuning the hydrophobicity of mesoporous silica materials for the adsorption of organic pollutant in aqueous solution, J. Hazard. Mater. 201 (2012) 107-114. [38] Q. Sui, J. Huang, S. Deng, G. Yu, Q. Fan, Occurrence and removal of pharmaceuticals, caffeine and DEET in wastewater treatment plants of Beijing, China, Water Res. 44 (2010) 417-426.

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[39] D. Aronson, J. Weeks, B. Meylan, P.D. Guiney, P.H. Howard, Environmental release, environmental concentrations, and ecological risk of N, N‐diethyl‐m‐toluamide (DEET), Integr. Environ. Assess. Manag. 8 (2012) 135-166. [40] Y. Tong, B.K. Mayer, P.J. McNamara, Triclosan adsorption using wastewater biosolids-derived biochar, Environ. Sci.: Water Res. Technol. 2 (2016) 761-768 [41] A. Ogutverici, L. Yilmaz, U. Yetis, F.B. Dilek, Triclosan removal by NF from a real drinking water source–Effect of natural organic matter, Chem. Eng. J. 283 (2016) 330-337.

EP

[42] A.A. Sharipova, S.B. Aidarova, N.E. Bekturganova, A. Tleuova, M. Schenderlein, O. Lygina, S. Lyubchik, R. Miller, Triclosan as model system for the adsorption on recycled adsorbent materials, Colloid Surf. A: Physicochem. Eng. Asp. 505 (2016) 193–196.

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[43] X. Zhu, Y. Liu, G. Luo, F. Qian, S. Zhang, J. Chen, Facile fabrication of magnetic carbon composites from hydrochar via simultaneous activation and magnetization for triclosan adsorption, Environ. Sci. Technol. 48 (2014) 5840-5848. [44] R. Xu, Y. Si, X. Wu, F. Li, B. Zhang, Triclosan removal by laccase immobilized on mesoporous nanofibers: strong adsorption and efficient degradation, Chem. Eng. J. 255 (2014) 63-70. [45] B. Liu, J. Lu, Y. Xie, B. Yang, X. Wang, R. Sun, Microwave-assisted modification on montmorillonite with ester-containing Gemini surfactant and its adsorption behavior for triclosan, J. Colloid Interface Sci. 418 (2014) 311-316. [46] Y. Liu, X. Zhu, F. Qian, S. Zhang, J. Chen, Magnetic activated carbon prepared from rice strawderived hydrochar for triclosan removal, RSC Adv. 4 (2014) 63620-63626.

19

ACCEPTED MANUSCRIPT

[47] C. Lei, Y.Y. Hu, M.Z. He, Adsorption characteristics of triclosan from aqueous solution onto cetylpyridinium bromide (CPB) modified zeolites, Chem. Eng. J. 219 (2013) 361-370. [48] S. Zhou, Y. Shao, N. Gao, J. Deng, C. Tan, Equilibrium, kinetic, and thermodynamic studies on the adsorption of triclosan onto multi‐walled carbon nanotubes, Clean–Soil Air Water 41 (2013) 539-547.

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[49] H.H. Cho, H. Huang, K. Schwab, Effects of solution chemistry on the adsorption of ibuprofen and triclosan onto carbon nanotubes, Langmuir 27 (2011) 12960-12967. [50] S.K. Behera, S.Y. Oh, H.S. Park, Sorption of triclosan onto activated carbon, kaolinite and montmorillonite: effects of pH, ionic strength, and humic acid, J. Hazard. Mater. 179 (2010) 684-691.

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[51] E.M. Cuerda-Correa, J.R. Domínguez-Vargas, F.J. Olivares-Marín, J.B. de Heredia, On the use of carbon blacks as potential low-cost adsorbents for the removal of non-steroidal anti-inflammatory drugs from river water, J. Hazard. Mater. 177 (2010) 1046-1053. [52] Z. Hasan, E.J. Choi, S.H. Jhung, Adsorption of naproxen and clofibric acid over a metal–organic framework MIL-101 functionalized with acidic and basic groups, Chem. Eng. J. 219 (2013) 537-544.

M AN U

[53] Z. Hasan, J. Jeon, S.H. Jhung, Adsorptive removal of naproxen and clofibric acid from water using metal-organic frameworks, J. Hazard. Mater. 209 (2012) 151-157. [54] S.M. Rivera-Jiménez, S. Méndez-González, A. Hernández-Maldonado, Metal (M= Co 2+, Ni 2+, and Cu 2+) grafted mesoporous SBA-15: effect of transition metal incorporation and pH conditions on the adsorption of Naproxen from water, Micropor. Mesopor. Mater. 132 (2010) 470-479. [55] Z. Yu, S. Peldszus, P.M. Huck, Adsorption of selected pharmaceuticals and an endocrine disrupting compound by granular activated carbon. 1. Adsorption capacity and kinetics, Environ. Sci. Technol. 43 (2009) 1467-1473.

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[56] Z. Yu, S. Peldszus, P.M. Huck, Adsorption characteristics of selected pharmaceuticals and an endocrine disrupting compound—Naproxen, carbamazepine and nonylphenol—on activated carbon, Water Res. 42 (2008) 2873-2882.

EP

[57] Y. Önal, C. Akmil-Başar, Ç. Sarıcı-Özdemir, Elucidation of the naproxen sodium adsorption onto activated carbon prepared from waste apricot: kinetic, equilibrium and thermodynamic characterization, J. Hazard. Mater. 148 (2007) 727-734.

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[58] N.A. Khan, Z. Hasan, K.S. Min, S.M. Paek, S.H. Jhung, Facile introduction of Cu+ on activated carbon at ambient conditions and adsorption of benzothiophene over Cu+/activated carbon, Fuel Process. Technol. 100 (2012) 49-54. [59] I. Ahmed, N.A. Khan, S.H. Jhung, Graphite oxide/metal–organic framework (MIL-101): remarkable performance in the adsorptive denitrogenation of model fuels, Inorg. Chem. 52 (2013) 14155-14161. [60] J. Kou, L.-B. Sun, Fabrication of nitrogen-doped porous carbons for highly efficient CO 2 capture: rational choice of a polymer precursor, J. Mater. Chem. A 4 (2016) 17299-17307. [61] P. Tan, Y. Jiang, X.-Q. Liu, D.-Y. Zhang, L.-B. Sun, Magnetically Responsive Core–Shell Fe3O4@ C Adsorbents for Efficient Capture of Aromatic Sulfur and Nitrogen Compounds, ACS Sustainable Chem. Eng. 4 (2016) 2223-2231. [62] Z. Hasan, S.H. Jhung, Removal of hazardous organics from water using metal-organic frameworks (MOFs): plausible mechanisms for selective adsorptions, J. Hazard. Mater. 283 (2015) 329-339.

20

ACCEPTED MANUSCRIPT

[63] N.A. Khan, Z. Hasan, S.H. Jhung, Adsorptive removal of hazardous materials using metal-organic frameworks (MOFs): a review, J. Hazard. Mater. 244 (2013) 444-456. [64] I. Ahmed, S.H. Jhung, Adsorptive desulfurization and denitrogenation using metal-organic frameworks, J. Hazard. Mater. 301 (2016) 259-276.

RI PT

[65] I. Ahmed, S. H. Jhung, Composites of metal–organic frameworks: Preparation and application in adsorption, Mater. Today 17 (2014) 136-146. [66] K.-Y.A. Lin, H.-A. Chang, Ultra-high adsorption capacity of zeolitic imidazole framework-67 (ZIF-67) for removal of malachite green from water, Chemosphere 139 (2015) 624–631.

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[67] F.-F. Liu, J. Zhao, S. Wang, P. Du, B. Xing, Effects of solution chemistry on adsorption of selected pharmaceuticals and personal care products (PPCPs) by graphenes and carbon nanotubes, Environ. Sci. Technol. 48 (2014) 13197–13206. [68] L. Xie, D. Liu, H. Huang, Q. Yang, C. Zhong, Efficient capture of nitrobenzene from waste water using metal–organic frameworks, Chem. Eng. J. 246 (2014) 142–149.

M AN U

[69] P.W. Seo, N.A. Khan, Z. Hasan, S.H. Jhung, Adsorptive removal of artificial sweeteners from water using metal-organic frameworks functionalized with urea or melamine, ACS Appl. Mater. Interfaces 8 (2016) 29799–29807. [70] P.W. Seo, I. Ahmed, S.H. Jhung, Adsorptive removal of pharmaceuticals and personal care products from water with functionalized metal-organic frameworks: remarkable adsorbents with hydrogenbonding abilities, Sci. Rep. 6 (2016) 34462.

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[71] C. Jung, J. Park, K. H. Lim, S. Park, J. Heo, N. Her, J. Oh, S. Yun and Y. Yoon, Adsorption of selected endocrine disrupting compounds and pharmaceuticals on activated biochars, J. Hazard. Mater. 263 (2013) 702-710. [72] I. Ahmed, S.H. Jhung, Applications of metal-organic frameworks in adsorption/separation processes via hydrogen bonding interactions, Chem. Eng. J. 310 (2017) 197–215.

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[73] I. Ahmed, M. Tong, J.W. Jun, C. Zhong, S.H. Jhung, Adsorption of nitrogen-containing compounds from model fuel over sulfonated metal-organic framework: contribution of hydrogen-bonding and acid-base interactions in adsorption, J. Phys. Chem. C. 120 (2015) 407-415. [74] B.N. Bhadra, I. Ahmed, S.H. Jhung, Remarkable adsorbent for phenol removal from fuel: Functionalized metal–organic framework, Fuel 174 (2016) 43-48.

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[75] P.W. Seo, I. Ahmed, S.H. Jhung, Adsorption of indole and quinoline from a model fuel on functionalized MIL-101: effects of H-bonding and coordination, Phys. Chem. Chem. Phys. 18 (2016) 14787-14794. [76] P. Tan, X. Y. Xie, X. Q. Liu, T. Pan, C. Gu, P. F. Chen, J. Y. Zhou, Y. Pan and L. B. Sun, Fabrication of magnetically responsive HKUST-1/Fe3O4 composites by dry gel conversion for deep desulfurization and denitrogenation, J. Hazard. Mater. 321 (2017) 344-352.

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Table 1. Properties of PPCPs. MW (g/mol)

LogKow

pKa

Water solubility (mg/L)

Functional group

Atenolol

266.3

0.16

9.6 *

13300

-NH2, -C=O, -O-, -OH, -NH

N,N-diethylmetatoluamide

191.3

2.5

-

1000

Triclosan

289.5

4.76

8.1

Naproxen

230.3

3.24

4.2

22

SC

-C=O, -N-

10

-OH, -O-

15.9

-COOH, -O-

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AC C

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* pKa of protonated atenolol

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PPCPs

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Table 2. Langmuir parameters (Q0 and b-values) for adsorptions of atenolol from water over AC and OAC(2.0). Langmuir parameters Adsorbents

AC

4.14×101

7.32×10-2

OAC(2.0)

1.06×102

3.23×10-1

R2

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b (mg/L)

AC C

EP

TE D

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Q0 (mg/g)

23

0.998 0.999

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Table 3. Relative adsorbed amounts of four PPCPs over AC and OAC(2.0), and number of H-bond acceptor and donor of PPCPs. Number of H-bond donor

12 h

Atenolol

2.9

2.9

3 (in base:4)

4

N,N-diethylmetatoluamide

1.4

1.4

1

0

Triclosan

1.5

1.5

Naproxen

2.1

SC

RI PT

4h

Number of H-bond acceptor

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qtOAC(2.0)/qtAC

2

2.1

3

AC C

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PPCPs

24

1

0

ACCEPTED MANUSCRIPT

(a)

(b)

OH O

N

RI PT

O

O

H N

(c)

Cl

SC

H2N

(d)

OH O

Cl

Cl

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O

OH O

AC C

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Scheme 1. Molecular structures of (a) atenolol, (b) N,N-diethyl-meta-toluamide, (c) triclosan, and (d) naproxen.

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NH2

H-bond O

Cl

O

N HO

Cl

O Cl

OH NH

O

O

O H

H

H

H

O O

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Oxidized Activated Carbons Oxidized Activated Carbons

O

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O

O

AC C

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Scheme 2. Plausible mechanism (H-bond) of adsorption of atenolol, N,N-diethyl-metatoluamide, triclosan, and naproxen over OAC(2.0) (from left to right).

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RI PT

100

60

SC

q12h (mg/g)

80

40

0 AC

M AN U

20

OAC(0.5)OAC(1.0)OAC(1.5)OAC(2.0)OAC(2.5)

Adsorbents

AC C

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Figure 1. Adsorbed quantities of atenolol over AC and OACs after adsorption for 12 h.

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100

OAC(2.0)

RI PT

60

OAC(1.0)

40

AC

SC

qt (mg/g)

80

0 0

2

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20

4

6

8

10

12

Time (h)

AC C

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Figure 2. Effect of contact time on adsorbed amounts of atenolol over AC, OAC(1.0) and OAC(2.0). The solid lines are guides to the eye.

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120

(a) OAC(2.0)

Ce/qe

60 40

AC

1.0

AC

0.5

20

RI PT

1.5

80

qe (mg/g)

(b)

2.0

100

OAC(2.0)

0

0.0 0

20

40

60

80

Ce (ppm)

0

10

20

30

40

50

60

M AN U

SC

Ce (ppm)

AC C

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Figure 3. (a) Adsorption isotherms and (b) Langmuir plots for adsorption of atenolol from water over AC and OAC(2.0).

29

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80 (a)

100

(b)

OAC(2.0)

40

AC

AC

40

20 20

0

0 0

2

4

6

8

10

0

12

2

4

(d)

OAC(2.0) 80

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80 AC

60 40

qt (mg/g)

qt (mg/g)

8

SC

100

(c)

6

10

12

Time (h)

Time (h) 100

RI PT

60

qt (mg/g)

qt (mg/g)

OAC(2.0)

60

80

OAC(2.0)

60

AC

40 20

20

0

0 0

2

4

6

8

0

12

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Time (h)

10

2

4

6

8

10

12

Time (h)

AC C

EP

Figure 4. Effect of contact time on adsorbed amounts of (a) atenolol (b) N,N-diethylmeta-toluamide (c) triclosan, and (d) naproxen over AC and OAC(2.0). The solid lines are guides to the eye.

30

100

100

80

80

q12h (mg/g)

120

60 40

60 40

20

20

(a)

(b)

0 2

4

6

8

10

12

0

14

SC

q12h (mg/g)

120

2

pH of atenolol solution

4

6

8

10

12

pH of DEET solution

150

M AN U

120

120

q12h (mg/g)

90

q12h (mg/g)

RI PT

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60 30

90 60 30

0

(c)

(d)

0

4

6

8

10

12

TE D

2

pH of triclosan solution

0

2

4

6

8

10

12

pH of naproxen solution

AC C

EP

Figure 5. Effect of pH on the adsorbed amounts of (a) atenolol (b) N,N-diethyl-metatoluamide (c) triclosan, and (d) naproxen over OAC(2.0) after adsorption for 12 h. The solid lines are guides to the eye.

31

14

RI PT

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100

SC

60

40

20

0 1

2

M AN U

q12h (mg/g)

80

3

4

5

Number of Cycles

AC C

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Figure 6. Reusability of OAC(2.0) for the adsorption in 12 h of atenolol after washing with acetone. The red line shows the adsorbed amount of atenolol over pristine AC.

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Atenolol Atenolol-adsorbed OAC(2.0)

OAC(2.0) -CH2

SC

Transmittance (a.u.)

Recycled OAC(2.0)

C-O-C

2100

1800

C-N

M AN U

C=O

C-O-H

1500

1200

900

-1

Wavenumber (cm )

AC C

EP

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Figure 7. FTIR spectra of fresh OAC(2.0), atenolol-adsorbed OAC(2.0), atenolol and recycled OAC(2.0). Major peaks related to atenolol are shown on the figure.

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ACCEPTED MANUSCRIPT Research Highlight Adsorption of PPCPs with wide acid-basic properties was investigated.

-

Activated carbon (AC), after oxidation, was applied in adsorption of PPCPs.

-

Favorable adsorption can be explained mainly with H-bond mechanism.

-

The direction of H-bond could be confirmed as H-donor from OACs.

-

Oxidized AC is competitive and reusable adsorbents for PPCPs removal.

AC C

EP

TE D

M AN U

SC

RI PT

-