Comparative Kinetic Study of the Adsorption Capacity of Walnut Shell and Its Biochar for Chromium Removal from Wastewater

Chromium is a toxic heavy metal that can pollute water from industrial and agricultural activities. Adsorption is a promising method for removing chromium from wastewater, and walnut shell is a sustainable and abundant biomass that can be used to produce biochar for adsorption. This study compares the effectiveness of walnut shell and walnut shell biochar for chromium removal from wastewater using adsorption. The effects of various parameters on chromium adsorption, such as pH, biochar dosage, and contact time, are investigated. The results show that both walnut shell and walnut shell biochar are effective adsorbents for chromium removal. However, walnut shell biochar exhibits a higher adsorption capacity and faster adsorption kinetics than walnut shell. The findings of this study suggest that walnut shell biochar is a promising adsorbent for chromium removal from wastewater. It is a sustainable and low-cost material that can be used to develop effective and efficient wastewater treatment systems. The kinetics of Cr adsorption will examine using pseudo-first-order, pseudo-second-order, and adsorption isotherms. The results demonstrated that the adsorption of Cr onto WS and BC followed pseudo-second-order kinetics, suggesting chemisorption as the rate-limiting step.