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Abstract English Summary Title: ”Chemical Studies on the Removal of Some Heavy Elements from Aqueous Solutions by Modified Pottery Materials” In this study it is intended to benefit from the use of low cost Egyptian pottery materials supplied from different sources for removal of selected heavy elements namely; cesium, barium, cobalt and copper from aqueous solutions. The thesis is divided into three main chapters including: chapter 1, the introduction, chapter 2, experimental and chapter 3, results and discussion. Chapter-1: Introduction The introduction includes brief account related to the environmental impact of the selected heavy metals. Descriptions of pottery materials as low cost adsorbents include raw and modified pottery materials. This part also includes adsorption process definition and its types of chemisorption and physisorption. It also contains a brief account about the different adsorbents used for removal of cesium, barium, cobalt, and copper from their aqueous solutions. Finally, the chapter ended with a literature survey on the adsorption of Cs(I), Ba(II), Co(II) and Cu(II) using clay, clay minerals as well as pottery materials. Chapter-2: Experimental The experimental part, defines the chemicals and standards used, as well as pottery materials used and the different methods applied for its physical and chemical characterization. It also includes procedures of measuring cation-exchange capacity, pH, loss of ignition and moisture content. The batch adsorption techniques used includes the effect of shaking time, pH, particle size, the concentration of inactive cesium, barium, cobalt and copper, adsorbent weight and temperature are also given. A brief description for ICP-OES instrument that used to determine metal ions concentration is given. In addition to other instruments used for characterization of pottery materials are also described. The sources and data of the pottery materials investigated are given in the following table as given in Table (3.1). Firing Source Temperature (°C) Sample Code Village Alfakhareen, Pottery House Abdeen, Ancient Egypt, Al-Fostat, Cairo Governorate. Aswan Powder AP ---- Aswan Fired AF 900 - 1100 Ezbet Elnamooss, Samannoud City, El-Gharbeya Governorate. Black Powder BP ---- Black Fired BF 800 -900 Village Alfakhareen, Pottery House Abdeen, Ancient Egypt, Al-Fostat, Cairo Governorate. White powder WP ---- White Fired WF ≈1200 Chapter-3: Results and discussion This chapter includes results and related discussion of physical and chemical characteristics of pottery materials and the data of adsorption of selected heavy elements on these materials. This chapter is divided into five parts; Part 1: include physical and chemical properities of pottery materials. It is obvious that the pH values of AP.AF, BP, WP and WF as determined in the experimental, are very close to each others but for BF, the pH increase after ignition from 6.8 to 8.4. CEC is found to be (28.0, 14.0, 27.0, 25.0, 18.0 and 16.0 meq/100g) for AP, AF, BP, BF, WP and WF, respectively. It is observed that black powder (BP) has the highest surface area compared to other samples The XRD analysis of pottery materials indicates that the mineral constituent is kaolinite, quartz, hematite, anatase, albite, calcite and montmorillonite. The XRF data indicated that the percent of silicon to aluminum for each clay mineral was similar to the theoretical formula of these kinds of clays, 2:1 for montmorillonite and 1:1 for kaolinite. Chemical analysis of all types of pottery materials revealed a relatively high Ca, Mg, Na and K percent, in which these ions can be exchanged easily with other ions without affecting the clay mineral structure. IR spectra showed that all samples exhibit absorption bands in the range of 400-4000 cm−1 according to each type of minerals present in each material of all pottery materials. The data of IR confirms the data of XRD. Part 2: The second part of results and discussion includes the sorption studies of Cs, Ba, Co and Cu on the six pottery materials. According to sorption studies, this chapter includes results and discussion related to the study of the different parameters affecting on heavy elements adsorption. The shaking time necessary to reach equilibrium was 2hr. But from the data, it could be seen that further increase in the shaking time beyond the 2hr for each ion resulted in a slight increase in the removal percentage. The optimum pH condition was found to be 7.0 for a maximum removal of cesium and barium on all pottery materials, 6.0 for cobalt and 5.0 for copper. The optimum shaking time was determined as 120 minutes for removal of Cs+, Ba2+, Co2+ and Cu2+ from aqueous solutions. For cesium the order of removal is: BP(67%)>AP(54%)>WP(49%)>AF(42%)>BF(38%)>WF(36%). The order of removal (%) of barium under is: BP (74%)>AF (65%) >AP =BF (55%)>WF (48%) >WP (37%) For cobalt the order of removal (%) is: WF (82%)>BP (60%)>AP (45%)>AF (36%)>WP (35%)>BF(32%) The order of removal (%) for copper is: WF(95 %)>BP(85%)>AF (51%)>AP (48%)>BF (45%)>WP (35%) The optimum particle size for all pottery materials was found to be 250 mesh for a maximum removal of cesium, barium, cobalt and copper by all pottery materials. The optimum weight of all pottery materials was found to be 0.2 g for a maximum removal of cesium, barium, cobalt and copper by all pottery materials. Part 3: includes the results of applying different empirical fitting models, which allow the systematic description of the influence of different conditions on selected ions behavior. These models include empirical adsorption isotherms such as Langmuir and Freundlcih. According to the isotherm models, the adsorption pattern of Cs+, Ba2+, Co2+ and Cu2+ on AP, AF, BP, BF, WP and WF were found to fit well with the Langmuir model. This model also assumes a chemical adsorption. Part 4: contains the kinetic modeling, it is found that the pseudosecond order adsorption model is more suitable to describe the adsorption kinetics of Cs+, Ba2+, Co2+ and Cu2+ ions on all pottery materials studied. It is clear that the experimental adsorption capacity (qe, experimental) and theoretical adsorption capacity (qe, calculated) values are in good match for second order model where for first order, they are different. Part 5: it investigates the sorption of Cs(I), Ba(II), Co(II) and Cu(II) by the fired pottery pots and its desorption. In this concern, three pottery pots representing the fired products of pottery materials i.e. Aswan pot, black pot and white pot are used for adsorption for single and multielement systems. The presence of multiple competing ions is more frequent than the existence of only one kind of ions, and the sorption in multi-component systems becomes much more complicated due to the competition between different ions as well as different types of coordination. Summary and Conclusion 156 The results of desorption studies illustrated that Cs(I) is eluted from the pottery materials using 0.1N NaOH. On the other hand, Ba(II), Co(II) and Cu(II) were easily desorbed using 0.1 N HCl solutions. The desorption of Cs(I) from loaded Aswan pot, black pot and white pot using NaOH (0.1N) was amounted to 76, 25 and 18 %, respectively. The highest desorption percents of Ba(II), Co(II) and Cu(II) from loaded Aswan pot, black pot and white pot using 0.1 N HCl were 55, 90 and 95 %, respectively. The desorption of Cs(I) from loaded Aswan pot, black pot and white pot using DI water, 0.1N NaOH, 0.1N HCl and tap water attained the order: NaOH> HCl > DI water > tap water Also, Ba (II) was desorbed from loaded Aswan pot, black pot and white pot using DI water, 0.1N NaOH, 0.1N HCl and tap water with the order: HCl > NaOH > DI water > tap water Also, Co (II) was desorbed from loaded Aswan pot, black pot and white pot using DI water, 0.1N NaOH, 0.1N HCl and tap water with the order: HCl > DI water >NaOH > tap water Finally,The desorption of Cu(II) loaded Aswan pot, black pot and white pot using DI water, 0.1N NaOH, 0.1N HCl and tap water exhibited the order: HCl > NaOH> tap water > DI water Hydrochloric acid showed the maximum desorption efficiency for Ba(II), Co(II) and Cu(II) but NaOH showed the maximum desorption efficiency for Cs(I) only. Conclusion The primary goal of the present thesis was to assess the effectiveness of pottery materials for the removal of selected heavy metals from solution. This was accomplished through laboratory batch experiments involving known amounts of crushed pottery materials and predetermined concentrations of the following heavy metals: Cs, Ba, Co and Cu. Batch adsorption tests were modelled using both the Langmuir and Freundlich equations and adsorption kinetics was also analyzed. Based on the results, the following is concluded: Batch studies on cesium, barium, cobalt and copper removal showed significant effects of the variables adsorbent dose, shaking time, initial metal concentration, pH etc. The results provide a good indication of the different operating conditions that would be required for efficient removal of each heavy metal from aqueous solution. Raw pottery materials show high adsorption capacity towards cesium and barium but modified pottery materials show high capacity towards cobalt and copper. pH is a significant factor in adsorption processes since it causes electrostatic changes in the solution. The maximum removal efficiency for Cs(I) is at pH 7.0 %, for Ba(II) at pH 7.0 for Co(II) at pH 6.0 and for Cu(II) at pH 5.0 Langmuir and Freundlich isotherms were observed to fit the equilibrium data and the model parameters were calculated at various temperatures using linearized equations. Langmuir Summary and Conclusion 158 isotherm model (R2≈1) is in good agreement with the experimental data as compared to Freundlich model. Kinetics data were best modeled by a pseudo second order kinetics equation. The desorption study was also carried out and showed that the hydrochloric acid (HCl) 0.1N is the best extractant. On the light of these data, the pottery materials effectively and quantitatively remove the studied elements from aqueous solutions. So, it would be useful to use these sorbents in the treatment of the waste solutions containing these elements. Also, it can be regarded as one of the promising materials in reprocessing and decontamination processes. Scope for Future Research The technology, which uses locally available adsorbent materials like Pottery materials, is extremely low cost, effective and viable. Following are the scope for future research: To explore the possibilities, other modifications or pretreatments of adsorbent to improve its adsorption capacity. Studies with actual industrial or nuclear wastewater to evaluate parameters for field applications |