Removal of Hexavalent Chromium from Synthetic Wastewater Using Corncob

Abstract

This study investigated the removal efficiency and adsorption capacity of hexavalent chromium (Cr(VI)) in synthetic wastewater using corncob as a biosorbent. Batch adsorption experiments were conducted to evaluate the factors affecting the adsorption process, including pH, biosorbent dosage, contact time, initial Cr(VI) concentration, and temperature. The concentration of Cr(VI) before and after adsorption was determined using UV–Visible spectrophotometry. The results showed that corncob achieved a maximum removal efficiency of 99.86% for Cr(VI), with a maximum adsorption capacity of 5.14 mg/g under the optimum conditions of pH 1, a biosorbent dosage of 2.0 g/L, a contact time of 180 min, an initial Cr(VI) concentration of 10 mg/L, and a temperature of 40 °C. The adsorption isotherm data were best described by the Freundlich isotherm model, whereas the adsorption kinetics followed the pseudo-second-order kinetic model. Furthermore, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDX) confirmed the presence of chromium on the corncob surface after adsorption, with a chromium content of 0.11 wt%. These findings indicate that corncob has high potential as a biosorbent for the removal of hexavalent chromium from wastewater. In addition to contributing to sustainable environmental management, its utilization provides a value‑added approach for the reuse of agricultural waste materials.