A Study of Hexavalent Chromium (Cr-Vi) Treatment Using Ni-Zno/Pani Nanocomposite under Visible Irradiation

Abstract

In recent years with the rapid economic globalization, pollution by industries and agriculture has increased, which results in decrease in the quality of ground and surface water. Pollution by heavy metals has become a serious health issue worldwide due to their non biodegradable and persistent nature. Heavy metals represent one of the most important kinds of pollutants, causing serious threats to the ecological balance. Thus, their removal from aqueous solution is a major environmental concern worldwide. The process of adsorption—being very simple, economical, and effective—is widely applied for the decontamination of wastewaters from heavy metals. The particle size, functional groups, and surface morphology of nickel-doped zinc oxide-polyaniline nanocomposite were characterized by XRD, FT- IR, and SEM, respectively. The concentration of Cr (VI) was determined by using Carry UV-Visible spectroscopy. The variables affecting the adsorption process, initial adsorbate concentration, pH, adsorbent dosage and contact time were optimized. Equilibrium adsorption isotherm and kinetic were also studied. The analysis of variance (ANOVA) revealed that all the variables studied had significant effects on the removal efficiency of Cr (VI). The obtained data showed that 4 mg/L initial Cr(VI) concentration, 4 solution pH, 0.7 g adsorbent dosage and 90 min contact time resulted in 95.6% adsorption. Equilibrium adsorption isotherm and kinetic studies showed that Langmuir isotherm and pseudo-second-order kinetic model fitted well to the experimental data.