Synthesis of zinc oxide nanoparticles reinforced clay and their applications for removal of Pb (II) ions from aqueous media

The aim of the study was to synthesize zinc oxide nanoparticles (ZnONPs) composite with clay by a novel route and then to explore the capability of composite of ZnONPs and silty clay (SC) as adsorbents for Pb (II) eradication from aqueous media by batch adsorption method. The effect of different operating factors like temperature, pH, dose and time of contact on the adsorption process were studied to optimize the conditions. Langmuir, Freundlich, Dubinin-Radushkevich (D-R) and Temkin isotherms were applied for the interpretation of the process. The R-2 and q values obtained from Langmuir model suggested that the process is best interpreted by this model. The values of adsorption capacity (q(m)) noted were 12.43 mg.g(-1) and 14.54 mg.g(-1) on SC and ZnONPs-SC respectively. The kinetic studies exposed that pseudo second order (PSO) kinetics is followed by the processes suggesting that more than one steps are involved to control the rate of reactions. Various thermodynamic variables such as change in free energy (DGb), change in enthalpy (DHb) and change in entropy (DSb) were calculated. Thermodynamic data suggested that Pb (II) adsorption on SC and ZnONPs-SC are spontaneous, endothermic and feasible processes. (C) 2021 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.