Adsorptive Removal of some Toxic Metal ions from Aqueous Solution using Moringa Oleifera Root Powder Biochar: Equilibrium, Kinetic and Thermodynamic Studies

The high cost of imported adsorbents poses a major barrier to effective industrial wastewater treatment, increasing the risk of environmental pollution due to insufficient removal of toxic contaminants. This study investigates a sustainable, low-cost alternative using carbonized Moringa oleifera root powder (CMORP), a locally sourced, eco-friendly material, for the adsorption of heavy metals from aqueous solutions. The metals studied include Pb²⁺, Cd²⁺, Cu²⁺, and Cr³⁺. Batch adsorption experiments were conducted to assess the effects of adsorbent dose, initial metal ion concentration, contact time, pH, and temperature. Optimal removal conditions were: 90 minutes contact time for Pb, and 30 minutes for Cd, Cu, and Cr; pH 5; 0.6 g adsorbent for Pb, 0.8 g for the others; initial concentrations of 30 mg/L for Pb and 40 mg/L for Cd, Cu, and Cr; and temperature of 50°C for all. Among five tested isotherm models, the Temkin isotherm best described the equilibrium data. Kinetic modeling indicated that the pseudo-second-order model provided the best fit. Thermodynamic analysis confirmed an endothermic adsorption process, with low enthalpy changes suggesting physisorption. These findings demonstrate CMORP’s potential as a cost-effective and efficient biosorbent for heavy metal remediation.