Sequestration of Ni(II) ions from water bodies by using gamma-sterilized biowaste

Abstract

Nickel has been recognized as an essential element in proper growth and development of plants and has wide range of physiological and morphological functions. But high concentrations of Nickel affect to the metabolic activity of plants. Therefore, it is essential to remove Ni(II) from water bodies. Cow-dung (CD) has been reported to be an adsorbent due to nitrogen containing functional groups that are capable of complexing various metal ions. The purpose of this work was to adsorb Ni(II) from an aqueous solution using CD. The bacterial contamination associated with CD has been overcome by sterilizing it by gamma irradiation dose of 4 kGy forming γ-CD. FTIR, SEM-EDX, XRD, and TGA-DTA techniques are used to characterize γ-CD. At solution pH of 5.0, adsorption capacity of is found to be 23.88 mg/g demonstrating monolayer adsorption. Equilibrium kinetics for adsorption is explained by pseudo-secondorder model. Intraparticle diffusion model was studied to know that diffusion is not a rate limiting step. The thermodynamic parameters like ΔG, ΔS and ΔH are computed by van’t Hoff equation. The negative values of ΔG and ΔH specifies spontaneity as well as exothermic behavior of the adsorption process. Column studies are also performed to check its applicability for larger volumes of sample.