Synergistic Recovery of Aqueous Lead Solution by Oil-Based Extractants and H2SO4 Using Liquid-Liquid Extraction Process

Lead (Pb), a toxic heavy metal, is commonly found in wastewater. Malaysia's Sewage and Industrial Effluent Discharge Standards (Standard B) stipulate a maximum allowable lead concentration of 0.5 mg/L. Prolonged exposure to elevated lead levels can cause chronic health issues. Research has explored the effectiveness of liquid-liquid extraction (LLE) for lead removal and recovery from aqueous solutions. The LLE process involved using oil-based extractants and a stripping agent consisting of 0.5 M sulfuric acid (H2SO4). The study evaluated three extractants: D2EHPA, TOA, and Aliquat 336, at concentrations of 0.005 M, 0.05 M, and 0.5 M. Results indicated that D2EHPA significantly outperformed TOA and Aliquat 336 in lead extraction and recovery. D2EHPA achieved nearly 100% lead extraction and 82.02% lead stripping efficiency. Optimal conditions for lead extraction were found to be a 0.5 M concentration of D2EHPA, a stirring speed of 250 rpm, a stirring duration of 1 h, and a 0.5 M concentration of H2SO4. The LLE method demonstrated potential for both cost-effective and environmentally friendly lead removal. This approach offers a promising solution for managing lead contamination in wastewater, aligning with regulatory standards and reducing environmental and health risks.