Electrochemical reclamation of soils contaminated with heavy metals

This study investigated the efficiency of electrochemical reclamation and remediation of soils contaminated with Co, Pb, Zn, Cu, and Cd. A loamy soil sample was collected and air-dried to a constant weight. The soil sample was pulverised and sieved using an Endecott sieve of 1.0 mm mesh. The sieved soil was thoroughly mixed and placed in a wooden box having internal dimensions 30 cm (length) × 4 cm (height) × 4 cm (width). The soil was spiked with an electrolyte of Co, Pb, Zn, Cu, and Cd until the soil was fairly wet. Using graphite electrodes, an electric field under a constant d.c. supply of 8.2 ± 0.9 mA and 5.6 ± 0.1 V was applied to mobilise metal ions in the soil sample. Soil samples were taken at 1 h intervals for 5 h and then air-dried. The metal contents were determined using an Atomic Absorption Spectrophotometer. The results demonstrated significant variability in the metal mobilisation across the soil samples. At the end of 5 h, Co showed a 51.4% reduction at the anode and a 41.3% increase at the cathode; Pb exhibited the highest efficiency, with a 55.2% reduction at the anode and a 154.7% surge at the cathode, underscoring the process’s strong potential for lead recovery; Zn showed a moderate 30.0% reduction at the anode, displayed a substantial 213.7% increase at the cathode, suggesting excellent recovery capabilities; Cu was effectively reclaimed, with a 59.3% reduction at the anode and a 97.7% increase at the cathode. Cadmium, despite a significant 56.7% reduction at the anode, had a modest 26.9% increase at the cathode, indicating the need for further optimisation. The study concluded that electrochemical reclamation is a promising method for heavy metal remediation, with varying degrees of efficiency depending on the metal.