In Situ Polyaniline Immobilized ZnO Nanorods for Efficient Adsorptive Detoxification of Cr (VI) from Aquatic System

Abstract

The elimination of toxic heavy metal ions from wastewater has been found to be of great importance in human as well marine animal wellbeing. Among various heavy metals, Cr (VI) has been found to be one of the highly toxic and carcinogenic heavy metals which are found to be dissolved in the water stream, the urgent treatment of which needs to be a priority. The present study demonstrates the fabrication of zinc oxide nanorods (ZnO NRs) and an immobilized polyaniline nanorod (ZnO@PAni NR) composite through an in situ free radical polymerization reactions. The material synthesis and purity were verified by X-ray diffractometer (XRD), Fourier transform infrared (FTIR), scanning electron microscope (SEM), energy dispersive spectroscope (EDS), and transmission electron microscope (TEM). Further, ZnO@PAni NRs were applied as an adsorbent for Cr (VI) in the aquatic system and exhibited a tremendous removal efficiency of 98.76%. The impact of operating parameters such as dose effect and pH on adsorption properties were studied. The uptake mechanism of Cr (VI) by ZnO@PAni was best explained by pseudo-second-order reaction, which suggested that the adsorption of Cr (VI) by the synthesized adsorbent material was processed by chemisorption, i.e., through formation of chemical bonds. The adsorption process proved viable and endothermic thermodynamically, and best supported by a Langmuir model, suggesting a monolayer formation of Cr (VI) on the surface of ZnO@PAni NRs.