Rice Husk Derived Activated Carbon for the Removal of Chromium (VI) from Wastewater

Abstract

Heavy metal contamination in wastewater poses a serious threat to environmental sustainability and human health due to the persistence and toxicity of metals such as lead (Pb), cadmium (Cd), chromium (Cr), and copper (Cu) (Jaishankar et al., 2014; Tchounwou et al., 2012). Conventional treatment methods, though effective, are often costly and generate secondary pollutants. This review critically evaluates the adsorption efficiency of biomass-derived adsorbents as sustainable alternatives. Emphasis is placed on adsorption mechanisms, kinetic and isotherm models, and operational parameters influencing performance. The applicability of models such as Langmuir, Freundlich, pseudo-first-order, and pseudo-second-order kinetics is discussed to understand adsorption behavior. The review concludes that biomass adsorbents exhibit high efficiency, with removal rates often exceeding 90%, and highlights pathways for optimization and large-scale implementation.