SYNTHESIS AND CHARACTERIZATION OF Al-PILLARED BENTONITE FOR REMEDIATION OF CHLORINATED PESTICIDE-CONTAMINATED WATER
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SYNTHESIS AND CHARACTERIZATION OF Al-PILLARED BENTONITE FOR REMEDIATION OF CHLORINATED PESTICIDE-CONTAMINATED WATER MOHAMED S. BASIONY1, SELEEM E. GABER1, HOSNY IBRAHIM2, AND EMAD A. ELSHEHY3 * 1
Central Laboratory for Environmental Quality Monitoring, National Water Research Center, El-Kanater, Kalyubeya, Egypt 2 Chemistry Department, Faculty of Science, Cairo University, Giza, Egypt 3 Nuclear Materials Authority, P.O. Box 530, El-Maadi, Cairo, Egypt
Abstract—The removal of pesticide contaminants from water is a key priority in environmental remediation, and requires intensive effort; this necessitates modification of the properties of pillared clays (PILCs) such as porosity, pore-volume, surface area, and synthesis methods. The purpose of the present study was to test the ability of Al-pillared bentonite (Al-PILB), using [Al13O4(OH)24(H2O)12]7+ and [Al30O8(OH)56(H2O)24]18+ (keggin cations, Al13 and Al30) as pillars, to adsorb chlorinated pesticides from contaminated water. In order to maximize intercalation and uniformity of layer stacking, various ratios of the nitrate forms of the synthesized keggin cations were intercalated into the natural bentonite (BT). The synthesized materials (Al-PILBs) were characterized by various techniques, including Xray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), Fourier-transform infrared (FTIR) spectroscopy, UV-Vis spectroscopy, and N2 adsorption-desorption measurements. Increases in basal spacing, surface area, and pore volume were observed. The adsorption capacity of the Al-PILBs for 17 types of chlorinated pesticides from contaminated water was better than using the BT alone, e.g. for heptachlor epoxide, dieldrin, and endrin at natural pH, the maximum adsorptions obtained at equilibrium solution concentrations of 16, 20, and 20 μg/L, respectively, were 59.2, 59.15, and 60 μg/g, whereas corresponding values using pristine BT were 34.68, 39.45, and 38.9, respectively. The data were best described by the Freundlich adsorption model. Keywords——Bentonite . Intercalation . Keggin cations . Pillared clay . Porous materials INTRODUCTION The increasing use of pesticides is a great global challenge due to their detrimental effect on surface water, air, soil, and living organisms. Thus, the use of pesticides has reduced the quantity and quality of global water resources. They exhibit harmful impacts and cause severe health problems, such as cancers, mutations, immuno-toxicity, paralysis, tonic clonic convulsions, and alterations to nervous and reproductive systems (El-Said et al. 2018). Most chlorinated pesticides such as endrin, dieldrin, and heptachlor epoxide are non-degradable; hence, they accumulate in human blood up to the warning levels established by international agencies (WHO 1989; IPCS 1992; WHO 2004). Several studies have focused on the removal of pesticides from water. One traditional approach for pesticide removal is based on decomposition into smaller or insoluble molecules that precipitate at the bottom of the water res
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