Enhanced electrokinetic removal of mercury from sandy soil using thioglycolic acid and lignocellulosic sawdust at acidic conditions

Mercury is a resistant environmental contaminant that is difficult to remediate due to its low mobility in natural soils, especially under neutral and alkaline conditions.Therefore, in this study, the efficiency of electrokinetic remediation of mercury-contaminated sandy soil was investigated using different laboratory conditions within varying pH ranges (4, 7, and 10) and using both thioglycolic acid and sawdust.The sandy soil was leached with mercury nitrate at a concentration of 300 mg/kg, and treatment was carried out under a constant electric field of 1.5 V/cm.The results showed that the acidic environment and the presence of thioglycolic acid achieved a maximum removal efficiency of 92.4%.This provided a stable complexation of mercury, increasing its transport towards the cathode, thus demonstrating maximum improvement in mercury mobility through increased solubility and decreased mercury hydroxide (Hg (OH)) deposition.Meanwhile, sawdust retained mercury via ion exchange and hydrogen bonding.While the removal efficiency reached 86.8% under acidic conditions of pH 4 alone.The pH and electrical conductivity patterns facilitated the electrochemical gradients that stimulated metal transport.These results demonstrate the synergistic potential of green chelators and biodegradable adsorbents in electrokinetic remediation systems to provide an effective and environmentally friendly method for remediating mercury in sandy soils.