alumina)

Accepted Manuscript Removing lead ions from water by using nanocomposite (rare earth oxide/alumina)

M.A. Ahmed, Samiha T. Bishay, S.M. Abd-Elwahab, Rania Ramadan PII: DOI: Reference:

S0167-7322(17)30861-9 doi: 10.1016/j.molliq.2017.05.122 MOLLIQ 7414

To appear in:

Journal of Molecular Liquids

Received date: Revised date: Accepted date:

28 February 2017 2 May 2017 26 May 2017

Please cite this article as: M.A. Ahmed, Samiha T. Bishay, S.M. Abd-Elwahab, Rania Ramadan , Removing lead ions from water by using nanocomposite (rare earth oxide/ alumina), Journal of Molecular Liquids (2017), doi: 10.1016/j.molliq.2017.05.122

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ACCEPTED MANUSCRIPT Removing lead ions from water by using nano composite (rare earth oxide/alumina) M. A. Ahmed(1), Samiha T. Bishay(2), S. M. Abd-Elwahab(1) and Rania Ramadan(1)* (1)

Materials Science Lab (1), Physics Department, Faculty of Science, Cairo University, Giza Egypt. Physics Department, Faculty of Girls for Arts, Science and Education, Ain Shams University, Cairo Egypt

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(2)

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Abstract

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Alumina nanoparticles were prepared using reverse microemulsion method with particle size 3.8nm. Also, the precipitation method was utilized to prepare samarium and dysprosium

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oxides with particle size 14nm and 8.6nm respectively. Nano composites consist of (x)R2O3/(100-x)y-Alumina; (x=16 and 44), (R=Sm and Dy) and (y= and ) were prepared with

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milling method. The characterization of all the prepared samples was studied using XRD analyses, transmitted electron microscope (TEM) and atomic force microscope (AFM). The

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removal efficiency of each prepared sample was measured using the atomic absorption spectroscopy. The study has clarified that the efficiency of the nano composite (x)Sm2O3/(100-x)

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-alumina; x=16 to remove lead ions from water after 24h is about 99.3%.

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Keywords: A. composite, B. Chemical preparation, C. Atomic force microscope- TEM-XRDatomic absorption spectroscopy, D. crystal structure

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*Corresponding author Dr. Rania Ramadan, [email protected]

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1. Introduction Adsorption is one of the most famous techniques used for removing heavy metals from wastewater. It is known that [1] low concentration of heavy metals like lead, chromium and cadmium has harmful reaction on animals, plants and humans due to their toxicity possessions.

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The dangers of wastewater do not arise only from the drinking water but also from the food

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cycle. Lead has highly damage effect on the living organism’s cell [2] such as the reproductive systems, nervous and, liver cells. The essential source of lead pollution is the industry, especially

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that of battery, glass and ceramic. Nanostructure Al2O3 has high attraction ability to the anion because it distinguishes by electron surface deficiency [3, 4]. Accordingly, Al2O3 nonmaterial is

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applied as adsorbents for the poison metal oxyanions [5]. During the last few years, several researchers [6-8] studied the different phases of alumina to choose the most important one in

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applications. The metastable phase () is involved with heating in transition sequences, which irreversibly ended to the stable α. The value of the phase transition temperature depends mainly

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on the preparation techniques.

The rare earth oxides (REOs) such as dysprosium, cerium, yttrium, samarium, europium and

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erbium have several important applications, and exhibit an adequate performance in luminescent devices [9-11], magnets [12], and catalysts [13-15] semiconductor glass, biochemical sensors

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and nan magnets [16-18], solar cells and nan electronics [19-21]. The importance of REOs is due to their special electron configuration of 4f electrons, which leads to distinguish chemical and

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physical properties [22-25]. Generally, the properties of REOs are high sensitive to the constitution as well as to the structure [26-28] particularly in the complicated state. The rare

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earth oxides surface possesses basic and acidic characters [29]. Also, it is known that, [29] the heavy rare earth oxides are less basic than the lighter REOs, where the radius of rare earth cation plays a significant role on the strength as well as on the number of basic sites of them. As a result, many researchers have recently focused their work, on the preparation of hydroxides and oxides rare earth with different methods [30, 31].

The particle size and particle morphology are two of the essential factors that affect significantly the chemical and physical properties of nanomaterials [32-34]. Therefore, recently several preparation techniques were considered to control the production of the nanoparticles 2

ACCEPTED MANUSCRIPT REOs , as examples, the microwave [30], solgel [35] and ultrasound [27]. In spite of the fact that, these methods have led to effective ways for the production of one dimensional nanorods, their implementation needs exceptional apparatuses (as autoclave) and some difficult processes to take away the surfactants/templates. The precipitation method is known as a simple, uncomplicated and plausible environmental technique. It is, therefore, considered as the most suitable method for fabricated nanoparticles REOs.

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Alumina has excellent physical and mechanical properties. On the other hand, rare earth

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elements, work as a kind of effective additives with their specific physical and chemical features.

preparation of composite consists of it with the REOs.

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As a result, physical and mechanical properties of alumina have been noticeably enhanced by

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The essential goal in this work is the improvement of the efficiency of alumina phases to remove toxic metal oxides from water. Reverse microemulsion and the precipitation method are

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considered to prepare nanoparticles of alumina and REO3 (samarium and dysprosium) respectively. A series of nanocomposites (Rare-earth/Alumina) with different weight percentage

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are prepared using the milling method. The structure and the morphology of each of the preparing samples have been studied. The application of all of these prepared nanomaterials to

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remove Pb2+ from water has been measured successfully. Also, the optimum economic conditions for the performance of this process have been examined. This work has environmental

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as well as economic benefits

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2. Experimental method:

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2.1 . Preparation

The chemicals utilized here to synthesize the samples were of analytical grade, aluminum nitrate (Al2(NO3)3. 9H2O ) (99.997% trace metals basis), ammonia (NH3.H2O) (≥99.98%), RE nitrate, Triton X-I00 (polycthylene glycol octylphenyl ether), n-butyl alcohol, cyclohcxanc, nitric acid and lead nitrate. All the chemicals brought from Sigma Aldrich company.

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Preparation of nano alumina Cyclohexane was used as oil phase while Triton (X-100) and butanol were used as surfactant and co-surfactant respectively. The three components were mixed magnetically with a magnetic stirrer (MODEL 78-1) with ratios 20:1:4 until the mixture becomes transparent. The mixture was divided into two parts. 1.6 M Al2(NO3)3 was added to the

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first part and ammonia was added to the second part until pH equals 11. Then the mixture

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containing ammonia is added drop by drop to the mixture containing Al2(NO3)3 until pH is adjusted at 8.5-9. The final mixture was stirred using magnetic stirrer for one hour and

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then aging for 24 h. The precipitate washed with ethanol by ultrasonic (Wise clean) and followed by centrifugation. The powder was dried for an hour at 600oC. Then the powder

was carried out after each step of annealing.

Preparation of nano rare earth oxide

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

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was annealed for two hours at different temperature 650oC ≤ T ≥ 1150oC. XRD analysis

The rare earth oxides were synthesized by precipitation method where Sm and Dy nitrates

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were used as rare earth element sources. The water solution (200ml) containing (0.036) mol Sm(NO3)3.6H2O or Dy (NO3)3.5H2O was introduced drop wise into (300) ml NH3.H2O solution

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as precipitating agent under dynamic stirring. The suspension product was preserved in a beaker for 48h at room temperature. The obtained precipitation was filtrated and washed for several

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times with deionized water and dried in air at 100oC. The thermal analysis was carried out for the prepared powder to obtain the suitable calcination temperature.

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Fig. (1.a) illustrates TGA analysis of Sm2O3 in which the curve demonstrates three weight loss steps. The first weight loss 26% from 40oC to 260oC refers to the dehydration of Sm(OH)3.

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The second weight loss 8% from 260oC to 525oC is due to the transformation of Sm(OH)3 to SmOOH. The third weight loss 1% from 525oC to 640oC is due to conversion of SmOOH to Sm2O3. The several steps of weight losses are shown in the TGA curve Fig. (1. b) for Dy2O3 . The first loss 55% is observed from 43oC to 308oC and is due to the removal of adsorbed water from the material. The second weight loss 4% from 308oC to 640oC indicates the complete formation of the required oxide. In the temperature range (650oC - 1000oC) no mass lass can be observed. According to the thermal analysis results, it is preferable to anneal the prepared samples at 650oC for 2h with rate 5oC/min [36, 37].

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Rare earth oxides /alumina phases composite preparation To create new nanomaterials with special properties useful in the nano technological

applications, the nanocomposites consist of different ratios of alumina and nano rare earth oxides were prepared and studied in this work. The rare earth oxides/ alumina nanocomposite are forming by adding each one of the two prepared alumina phases to different ratios of the rare

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earth oxides according to the formula xRE2O3/(100-x)Al2O3; x= 16, 28, 37 and 44 weight

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percentage. Milled the mixture for 2h and then annealed for 2h in the oven at 400oC with heating/cooling rate 5oC/ min to remove the water vapor from the samples. X-Ray Diffraction

Samples Characterization

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2.2.

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was used to investigate the phase formation of the desired composite.

A Proker D8 advance X- ray diffractometer with CuKα as a radiation source (wavelength λ = 1.5418Å) was used to perform XRD analysis. The characterization was checked out at room

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temperature for the prepared samples after each calcination temperature in a broad range of Bragg angles 2θ (20o≤2θ≤80o) with 0.02º step size. The X-ray data were employed to calculate

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the crystallite size (D) using Scherrer’s formula [38].

k is the particle shape factor, λ is the wavelength, β is the full-width at half maximum, and θ is the

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position (angle) of the maximum corrected peak.

Scanning Probe atomic force microscope - Non-Contact mode of model Wet – (SPM-9600)

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(Shimadzu made in Japan) has been utilized to measure the roughness, porosity and surface area of the investigated samples. AFM was performed to measure the vertical and horizontal

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deflection of the cantilever with Pico-meter resolution. Transmission Electron Microscope (TEM) (The JEM-2100) is used to investigate the particle shapes.

2.3. Batch Experiment of Pb2+ removal To study the optimum pH values of Pb2+ removal, the experiments were performed in a series of 250 mL flasks containing (0.1g/L) of nanomaterial powder in 2ppm of lead nitrate. Lead ions adjusted at different pH values from 2-11. The investigated solutions were dispersed well using electric shaker (ORBITAL SHAKER SO1) for 60 min at 250 rpm at room

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ACCEPTED MANUSCRIPT temperature. The filtration was carried out for the solution using 0.2µm syringe filter. Atomic absorption spectroscopy (Zeenite 700P, Analytical Jena) was used at 25oC for measuring lead concentrations in the filtrate solution. The average value of the result was calculated after repeating the experiment for 3 times. The optimum contact time was examined by repeating the above step with adjusting the pH value at its optimum measuring value and the atomic absorption was measured after different

%

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Removal (Adsorption) efficiency % =

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contact times (1 to 24h). The nanomaterial removal efficiency is calculated according to [39].

(2)

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where Co is the initial concentration (mg/L) of the lead ion solution and Cf is its final

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concentration.

3. Results and Discussion

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Fig. (2) illustrates the X- ray diffraction pattern at 25oC for the prepared alumina

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samples calcined in air at different temperatures compared with [ICDD 00-029-0063] and [ICDD 04- 004-2852] of γ-Al2O3 and α-Al2O3 respectively. XRD pattern for the as-prepared sample without any heat treatment shows a diffuse peak indicating amorphous structure of

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this sample. It is worthwhile noticing that, after annealing the samples in air at 650oC and 700oC, the essential peaks of γ-Al2O3 [ICDD 00-029-0063] were observed. The appearance

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of broad peaks at 700oC confirms the formation of γ-Al2O3 with ultra-fine crystallite size (2.8nm). This value has been calculated from Scherrer equation. By increasing the annealing

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temperature to 900oC a better crystallinity was obtained with completely identifications of [ICDD 00-029-0063]. This implies that, the stability of the single phase formation of γAl2O3, with cubic spinel structure and space group Fd-3m was begun from 650oC and settled up at 900oC where the crystal size increased from 2.4nm to 3.8nm.With increasing the calcination temperature to more than 900oC, a perfect phase formation of α-Al2O3 with space group R-3C was obtained as matched with the [ICDD 04-004-2852]. This implies that the cubic structure is deformed and converted into hexagonal shape. Accordingly, these results give single metastable phase of γ-Al2O3 in the temperature range from 650oC to 900oC and 6

ACCEPTED MANUSCRIPT stable single phase of α-Al2O3 from 950oC to above 1150oC. A comparison of these results with that obtained in [40], showed that the two phases of alumina were successfully prepared in this work by reverse micro emulsion method at low annealing temperatures and better crystallite. Fig. (3: a, b) shows the XRD patterns of the oxide specimens of Sm2O3 and Dy2O3 as prepared and after annealed at 650oC, compared by ICDD cards [00-042-1461] and [04-002-

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6757] respectively. It is remarkable that, all the obtained peaks of the investigated samples

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are satisfactorily indexed. This refers to the single phase formation of the two prepared rare [14, 33]. The crystallite size and lattice parameters

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earth oxides with space group

were calculated using Scherrer’s equation [41] and listed in the Table (1).

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Fig. (4.a) represents TEM micrograph of Sm2O3 sample after calcination at 650oC. It is shown from the figure nanobundles of polycrystalline with dimensions (51nm x 177nm).

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While; Fig. (4. b) clarifies the TEM micrographs of γ-Al2O3 which appears as a spherical particles with average size nearly equal 5nm. The two types of particles were homogenously

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appeared in Fig. (4.c) of the nanocomposite (x) Sm2O3/(100-x) γ-Al2O3; x=44 Fig. (5: a, b) show the TEM micrographs of the nano prepared samples of Dy2O3 and

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γ-Al2O3 respectively. The particles of both of them are characterized by nano sphere shape with particle size 8nm and 5nm respectively. Fig. (5. c) clarifies the TEM micrographs of the

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composites xDy2O3/(100-x)γ-Al2O3; x= 44 weight percentage. It is noted that the two shapes of particles are distributed homogenous.

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Three dimensional AFM micrographs of the composoites (xSm2O3/(100-x)γ-Al2O3, xSm2O3/(100-x)α-Al2O3) and (xDy2O3/(100-x)γ Al2O3 and xDy2O3/(100-x)α-Al2O3); x=44

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weight percentage are shown in Fig. (6: a-d). In order to obtain quantitative information about some parameters such as surface roughness as well as surface area calculated from the AFM image by microscope software and reported in Table (2). Most of atoms are unsaturated on the nanoparticles surface and can easily be attracted by other atoms. Nanomaterials were characterized by high and rapid adsorption ability [39]. The dependence of the Zeta potential () on the pH values was examined to evaluate the stability of the suspended alumina particles. As well known, [42, 43], the dispersion or aggregation states of dispersive materials in an aqua solution are strongly affected by the surface charge particles. In general, the high surface charge densities create repulsive forces 7

ACCEPTED MANUSCRIPT that cause the substance to be highly dispersive. More specifically, the amount of OH- and H+ ions on the surface characterizes the chemical properties of the suspended materials. The large zeta potential indicates that the particles repel each other and accordingly they do not gather. On the other hand, for suspended particles with small zeta potential no forces exist to prevent their collection and thus flocculations may take place. The stability of the suspended materials has been considered in the zeta potential ranges ( ˂ -30 mV,  > +30 mV) [39].

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Fig. (7: a, b) displays the relation between pH value and zeta potential for γ and α-alumina. It can be concluded from this figure that the particles are stable at pH 9 for the two phases of

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alumina because  reached its largest value and it was larger than -30 mV. Also, it is noted that the value of α-Al2O3 is larger than that of γ-Al2O3 which indicates that the α-Al2O3 is

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more stable than γ-Al2O3.

As has been reported in [39], pH value of a solution plays a significant role on the

charge.

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removal efficiency due to its effect on the adsorbent ionization and on the solution surface Accordingly, the atomic adsorption measurements were used to study the relation

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between the removal percentage and pH value of lead nitrate solution at pH ranged from (2 to 11) as discussed previously in the experimental part. It is well known [44] that at higher pH

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values, there is a chance for cations to bind the OH- on the surface of nanostructure alumina. With reducing the pH value passing by the neutral point of surface charge, the OH- is liberated

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from the surface. A continuous decrease of pH revealed that the surface of nanoparticles alumina carries +ve charges and this is a suitable condition to adsorb anions [43]. Although, the data in

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Fig. (8) show nearly equal removal percentage at pH 6 and 9, the favorable experimental work is considered at pH 6. This is because the increase in the pH of the solution to values above 7, leads

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to a considerable increase in the calculated removal percentage owing to the lead precipitation and adsorption effects [43]. Accordingly, pH 6 is the optimum value for Pb2+ adsorption. A closer look at Fig. (8) illustrates a higher removal percentage of Pb2+ using γ-Al2O3 than that of α-Al2O3 , This is attributed to the fact that γ-Al2O3 is characterized by lesser particle size and greater surface area. Fig. (9. a) shows the relation between the contact time and the removal percentage of Pb2+ ions from water at pH 6 using the two alumina phases. The figure illustrates that, the removal percentage, using  alumina, extends to about 91% after 1h and up to 94.5% after 7h. One can interpret this behavior as follows, the removal process occurs in two steps, at the beginning 8

ACCEPTED MANUSCRIPT alumina has rapid uptake and then followed by slower uptake. The rapid uptake is associated with the external surface adsorption, and when all the active sites occupied, the equilibrium is reached and the alumina uptake increased with small rate. The results of this work clarified that, the efficiency of the prepared  and  alumina nanoparticles to remove Pb2+ from water after 7h reached (≈94.5% and 92% ) respectively. Fig. (9. b) shows the relation between the contact time and the removal percentage of Pb2+ ions from water at pH 6 using the two rare earth oxides

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(Sm2O3 and Dy2O3). It is noted that, the removal efficiency percentage, using the two prepared nano rare earth oxides Sm2O3 and Dy2O3, after 1h reached 30 % and 15 % respectively, and for

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both it reached up to 93% after 5h. It is noticed also that the removal efficiency percentage of each of Sm2O3 and Dy2O3 after 5 h increases slowly and reaches to 99.5% after 24h. This is

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attributed to the magnetic property of metals that appears on the surfaces of the metal oxides of the nanoparticle rare earth oxide. The presence of magnetic properties on the surface plays an

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essential role in the adsorption process. Thus the surfaces can be regarded as a deviation from the infinite 3D crystal; the electronic structure, in turn, causes deviations in the magnetic structure.

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Finally, the adsorption of lead contributed to the magnetic effect associated with the 4f electrons even rather than surface area and roughness.

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Fig. (10: a, b) clarifies in details the comparison of the removal of all the prepared nano materials after contact time 1h and 24h respectively. Fig. (10.a) clarifies that, after contact time

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one hour, the best removal efficiency to remove Pb2+ from water reached 93% using the composite (xSm/(100-x) γ-alumina); x= 16 weight percentage. While; Fig. (10. b) showed that

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after contact time 24h, the best removal of Pb2+ from water using of the nano rare earth oxides Sm2O3 and Dy2O3 are (99.6% and 99.4%) respectively. As it is well-known, the nano rare earth

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oxides are more expensive. The results of Fig. (10. b) confirmed that, the lead removal can be successfully obtained with efficiency of 99.3% by forming a nanocomposite (xSm/(100-x) γalumina); x= 16 weight percentage. This result assures an economic conclusion concerning very good impact in environmental pollution and water detoxification.

4. Conclusion This work emphasizes that the reverse micremulsion method is suitable for preparing alumina nanoparticles. Also, the precipitation and milling methods can be used to synthesize the nano REOs (Sm2O3 and Dy2O3) and the nano composites REOs/Alumina respectively. 9

ACCEPTED MANUSCRIPT Nanobundles Sm oxide is clearly polycrystalline and each nanobundle is composed of individual nanorods. However, Dy oxide is formed as homogenous semi sphere particles. Gama alumina is characterized by higher roughness surface than alfa alumina as clarified from the AFM morphology study. The efficiency of the prepared γ and α alumina nanoparticle to remove Pb2+ from water after

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7h was found to be of the order of 94.5% and 92% respectively. On the other hand, the removal

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efficiency percentage of each of Sm2O3 and Dy2O3 after 24h to remove Pb2+ from water is 99.6%

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and 99.4% respectively. In this respect it should be born in mind that nano REOs are very expensive. Thus, some kind of balance should be attained between the improvement of the removal efficiency and the expense of adding nano REOs. The optimum conditions have to be

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fixed.

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The present study reveals that the composite which is formed by adding a small weight percentage ratio (x=16%) of the nano rare earth oxide to nano -alumina is able to remove lead

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ions from water successfully with a very high efficiency about 99.3%. This result leads to significant economic benefits. It illuminates the fact that water purification from lead ions can be

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implemented by much less expenses than was expected hitherto.

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ACCEPTED MANUSCRIPT Figure Captions:

Fig. (1: a, b): Thermal analysis TGA curves of (a) Sm2O3 and (b) Dy2O

(2): XRD patterns of the alumina nanoparticles annealed in air at different

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Fig.

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temperatures for 2h with the ICDD cards [00-029-0063] and [04-004-2852].

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Fig. (3: a, b): Room temperature XRD of the rare earth oxides samples as prepared and

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after annealed at 650oC (a) Sm2O3 and (b) Dy2O3.

Fig. (4: a-d): TEM Micrograph of (a) Sm2O3, (b) γ-Al2O3, (c) xSm2O3/(100-x)γ-Al2O3; x=44

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weight percentage.

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weight percentage

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Fig. (5: a-d): TEM Micrograph of (a) Dy2O3, (b) γ-Al2O3, (c) xDy2O3/(100-x)γ-Al2O3; x=44

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Fig. (6: a, b): 3D AFM image of (a) xSm2O3/(100-x)α-Al2O3 (b) x Sm2O3/(100-x)γ-Al2O3 (C) xDy2O3/(100-x)α-Al2O3 (d) xDy2O3/(100-x)γ-Al2O3 ; x=44 weight percentage

Fig. (7: a, b): Zeta potential of alumina in water as function of pH (a) γ-Al2O3 (b) α-Al2O3

13

ACCEPTED MANUSCRIPT Fig. (8): The dependence of the removal percentage of Pb+2 on the pH values using γ-Al2O3 and α-Al2O3. Conditions: sorbent concentration 2mg/L, temperature 293K and contact time 1h.

T

Fig. (9): The effect of contact time on the removal percentage of Pb 2+ ions using each of (a)

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α-Al2O3 and γ-Al2O3 (b) of Dy2O3 and Sm2O3. Conditions: sorbent concentration 2mg/L,

CR

temperature 293K and pH= 6.

US

Fig. (10. a): The removal efficiency of the prepared nano particle of γ-Al2O3, -Al2O3,

AN

Dy2O3, Sm2O3 and the nano composites (x)R2O3/(100-x)y-Alumina; (x=16 and 44), (R=Sm

M

and Dy) and (y= and ) to remove Pb2+ from water after 1h

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Fig. (10. b): The removal efficiency of the prepared nano particle of γ-Al2O3, -Al2O3,

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Dy2O3, Sm2O3 and the nano composites (x)R2O3/(100-x)y-Alumina; (x=16 and 44), (R=Sm

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and Dy) and (y= and ) to remove Pb2+ from water after 24h

14

ACCEPTED MANUSCRIPT Table 1: XRD calculated parameters Calculated cell parameter Volume Å3

a (Å)

Volume Å3

1311.19

10.9306

1305.97

1220.51

1217.16

a (Å) 14

Cubic

Dy2O3

8.6

Cubic

10.9451 10.6868

10.6770

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Sm2O3

Unit cell parameters from ICDD card

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Crystallit Structur e size e (nm)

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Sample

Table 2: AFM calculated parameters (mean radius and surface area) of grain

Roughness

0.09

0.162

0.138

0.042

1.341

0.135

0.064

1.77

M

2.04

AN

Surface Area (µm2) 0.005

AC

CE

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xSm2O3/(100-x)αAl2O3; x-44 xSm2O3/(100-x) γAl2O3; x=44 xDy2O3/(100-x)αAl2O3; x=44 xDy2O3/(100-x) γAl2O3; x=44

Mean Radius (µm) 1.45

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Sample

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boundaries of samples.

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0.123

ACCEPTED MANUSCRIPT 1.0

1.0 o

TGA (mg)

0.6 o

Start 260 C o End 525 C Weight loss 8%

0.4

Start 525 C o End 640 C Weight loss 1%

0.2

0.4 o

Start 308 C o End 642 C Weight Loss 4%

0.2

o

0.0

0.0 200

0

200

400

600

800

1000

400

600

800

1000

1200

o

Temp ( C)

1200

o

IP

(b)

T

T( C)

(a)

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M

AN

US

CR

Fig. (1: a, b): Thermal analysis TGA curves of (a) Sm2O3 and (b) Dy2O3

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TGA (mg)

0.6

o Start 43 C o End 308 C Weight Loss -55%

0.8

Start 40 C o End 260 C Weight loss 26%

0.8

16

(1010)

(214) (300)

(211)

(024)

(113)

(110)

(104)

(012)

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o 1150 C o 1000 C o 950 C

(440) (511)

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(400)

o 900 C

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Intensity (a.u)

(220) (311)

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o 800 C

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o 700 C

o 650 C

as prepared

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CDD  [00-029- 0063]

M

CDD  [04 -004 - 2852]

20

40

60

80

ED

2

AC

CE

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Fig. (2): XRD patterns of the alumina nanoparticles annealed in air at different temperatures for 2h with the ICDD cards [00-029-0063] and [04-004-2852].

17

(222)

(222)

ACCEPTED MANUSCRIPT

(800)

(400) (411) (332) (431) (440) (433) (611) (622) (444)

(211)

(662) (840)

(800)

(332) (431) (440) (541) (622) (444)

(400) (411)

(211)

as prepared

(622)

650oC

650oC

T CR

IP

I (a.u)

I (a.u)

as prepared

ICCD of Sm2O3

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[00-042-1461]

10 15 20 25 30 35 40 45 50 55 60 65 70 75 80

ICCD Card of Dy2O3 [04-002-6757

10 15 20 25 30 35 40 45 50 55 60 65 70 75 80

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2

2

AC

CE

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ED

M

(a) (b) Fig. (3: a, b): Room temperature XRD of the rare earth oxides samples as prepared and after annealed at 650oC (a) Sm2O3 and (b) Dy2O3.

18

US

CR

IP

T

ACCEPTED MANUSCRIPT

(a)

(b)

γ-Al2O3

AC

CE

PT

ED

M

AN

Sm2O3

1000 1/um 50 nm

(c)

Fig. (4: a-d): TEM Micrograph of (a) Sm2O3, (b) γ-Al2O3, (c) xSm2O3/(100-x)γ-Al2O3; x=44 weight percentage.

19

γ -Al2O3

(a)

CR

50 nm

(b) )

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M

AN

US

Dy2O3

IP

T

ACCEPTED MANUSCRIPT

20 nm

PT

1000 1/µm

(c)

AC

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Fig. (5: a-d): TEM Micrograph of (a) Dy2O3, (b) γ-Al2O3, (c) xDy2O3/(100-x)γ-Al2O3; x=44 weight percentage

20

CR

IP

T

ACCEPTED MANUSCRIPT

(b)

(d)

AC

(c)

CE

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ED

M

AN

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(a)

Fig. (6: a, b): 3D AFM image of (a) xSm2O3/(100-x)α-Al2O3 (b) x Sm2O3/(100-x)γ-Al2O3 (C) xDy2O3/(100-x)α-Al2O3 (d) xDy2O3/(100-x)γ-Al2O3 ; x=44 weight percentage

21

ACCEPTED MANUSCRIPT

20

40

10

20

0 4

6

8

10

12

0

Zeta pot (mV)

pH

-20 -30

4

6

8

10

-40

-100

(b)

T

-80

(a)

AC

CE

PT

ED

M

AN

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Fig. (7: a, b): Zeta potential of alumina in water as function of pH (a) γ-Al2O3 (b) α-Al2O3

22

12

pH

CR

-60

2

-60

-40 -50

-20

IP

Zeta pot (mV)

2 -10

ACCEPTED MANUSCRIPT

Al2O3 Al2O3 95

85 80

T

75 70

IP

Removal efficiency %

90

65

55 2

4

6

8

10

12

US

PH

CR

60

AC

CE

PT

ED

M

AN

Fig. (8): The dependence of the removal percentage of Pb+2 on the pH values using γ-Al2O3 and α-Al2O3. Conditions: sorbent concentration 2mg/L, temperature 293K and contact time 1h.

23

ACCEPTED MANUSCRIPT

Dy2O3 Sm2O3 100

60

40

80

60

T

80

40

IP

Removal efficiency % -Al2O3

20

-Al2O3

20

0 0

5

10

15

20

25

0

CR

Removal efficiency %

100

0

US

Contact time (h)

AN

(a)

5

10

15

20

25

Time(h)

(b)

AC

CE

PT

ED

M

Fig. (9): The effect of contact time on the removal percentage of Pb2+ ions using each of (a) α-Al2O3 and γ-Al2O3 (b) of Dy2O3 and Sm2O3. Conditions: sorbent concentration 2mg/L, temperature 293K and pH= 6.

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ACCEPTED MANUSCRIPT

100

93

91 87

90

After 1h

92

89

88

80 67.5

Removal Efficency %

70

T

60 47

IP

50 40 32

CR

30.5

30 20

19

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15.7

10

S2

S3

S4

S5

S6

S7

S8

S9

S10

S11

S12

M

S1

AN

0

ED

(a)

CE

PT

Fig. (10. a): The removal efficiency of the prepared nano particle of γ-Al2O3, -Al2O3, Dy2O3, Sm2O3 and the nano composites (x)R2O3/(100-x)y-Alumina; (x=16 and 44), (R=Sm and Dy) and (y= and ) to remove Pb2+ from water after 1h S1: gamma alumina

S3:Sm2O3 S4: Dy2O3

S8: 44 Sm2O3/56 alpha alumina

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S2: alpha alumina

S9: 16 Dy2O3/84 gamma alumina S10: 44 Dy2O3/54 gamma alumina

S5: 16 Sm2O3/84 gamma alumina

S11: 16 Dy2O3/84 alpha alumina

S6: 44 Sm2O3/56 gmma alumina

S12: 44 Dy2O3/56 alpha alumina

S7:16 Sm2O3/84 alpha alumina

25

ACCEPTED MANUSCRIPT

120

After 24h 100

T IP

60

CR

Removal Efficency %

80

US

40

0

S3

S4

S5

PT

S6

M

S2

ED

S1

AN

20

S7

S8

S9

S10

S11

S12

(b)

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Fig. (10. b): The removal efficiency of the prepared nano particle of γ-Al2O3, -Al2O3, Dy2O3, Sm2O3 and the nano composites (x)R2O3/(100-x)y-Alumina; (x=16 and 44), (R=Sm and Dy) and (y= and ) to remove Pb2+ from water after 24h

AC

S1: gamma alumina S2: alpha alumina

S8: 44 Sm2O3/56 alpha alumina

S3:Sm2O3

S9: 16 Dy2O3/84 gamma alumina

S4: Dy2O3

S10: 44 Dy2O3/54 gamma alumina

S5: 16 Sm2O3/84 gamma alumina

S11: 16 Dy2O3/84 alpha alumina

S6: 44 Sm2O3/56 gmma alumina

S12: 44 Dy2O3/56 alpha alumina

S7:16 Sm2O3/84 alpha alumina 26

ACCEPTED MANUSCRIPT 120

After 24h 100

T

60

IP

Removal Efficency %

80

CR

40

US

20

ED

M

AN

0

PT

Graphical Abstract

AC

CE

The removal efficiency of the prepared nanoparticle of γ-Al2O3, -Al2O3, Dy2O3, Sm2O3 and the nanocomposites (x)R2O3/(100-x)y-Alumina; (x=16 and 44), (R=Sm and Dy) and (y= and ) to remove Pb2+ from water after 24h

27

ACCEPTED MANUSCRIPT Highlights 

Nano composites consist of (x)R2O3/(100-x)y-Alumina were prepared with milling method



The characterization of the prepared samples was studied using XRD, (TEM) and (AFM) The removal efficiency of each prepared sample was measured



The efficiency of (16)Sm2O3/(84)-alumina to remove Pb2+ from water is about

IP

T



AC

CE

PT

ED

M

AN

US

CR

99.3%

28