Sustainable Detoxification of Galvanizing Wastewater Using Potassium Permanganate and Rice Husk-Derived Activated Carbon

Abstract

This study investigated the potential of KMnO4-activated Rice Husk (RH) Carbon for detoxifying industrial wastewater contaminated with heavy metals, particularly those originating from galvanization processes. This research aimed to develop a novel adsorbent, KMnO4-activated RH Carbon, and evaluate its effectiveness in detoxifying wastewater contaminated with heavy metals. The adsorbent was prepared by carbonising pre-treated rice husks at 700 °C and subsequently activating with KMnO₄. Batch adsorption experiments were conducted to evaluate the effects of pH, contact time, adsorbent dosage, and agitation speed on the removal of Cu²⁺, Fe²⁺, and Zn²⁺ ions. The impact of pH on absorption efficiency showed that optimum treatment occurred at pH 7 with 75%, 80%, and 54% remediation for Cu3+, Fe2+, and Zn2+, respectively. For contact time, optimum treatment occurred after 80 minutes of rotation, with the metals having 25%, 67%, and 50% remediation, respectively. Optimum treatment was achieved at a 6g dosage of the activated carbon, with the metals having 75%, 98%, and 91% remediation, respectively. The effect of rotating speed showed that optimum treatment occurred at 100rpm. At 100rpm, the metals had 62%, 85%, and 68% remediation, respectively. Optimal removal efficiencies were observed at a pH of 7, a 80-minute contact time, a 6-g adsorbent dosage per 100 mL of wastewater, and an agitation speed of 150 rpm. Under these conditions, maximum removal efficiencies reached 75% for Cu²⁺, 98% for Fe²⁺, and 91% for Zn²⁺.