Removal of Typical Heavy Metals from Soil by the Synergistic Interaction between Microbubbles and Washing Agents: Experiments, Influences, and Mechanisms

Soil contamination by heavy metals poses serious risks to human health due to their high toxicity and resistance to biodegradation, especially when they accumulate through the food chain. Soil drenching technology is one of the most promising methods for soil pollution remediation. In this research, microbubbles were introduced into the disodium ethylenediamine tetraacetate(EDTA-2Na) solution during soil drenching, combined with Polysorbate 80(TW-80) to remove heavy metals(Cu, Cd) from the soil. The microbubbles contributed to concentrating heavy metals, thus lowering their levels in the solution. The efficiency of heavy metal removal was found to be positively correlated with both time and detergent concentration, and negatively correlated with pH levels. Under conditions where the washing time was 120 minutes, EDTA-2Na concentration was 1 g/L, TW-80 concentration was 2 g/L, the solid-liquid ratio was 1:30, the gas-liquid ratio was 1:3, and the pH was maintained at 3, the removal rates for Cu and Cd were 86.67% and 85.52%, respectively. The Community Bureau of Reference (BCR) sequential extraction procedure revealed that intensive was Ahile et al., 2021 hing with microbubbles effectively eliminated acid-soluble (F1) and reducible (F2) heavy metals from the soil, thereby mitigating their detrimental effects on soil ecosystems. These insights offer a theoretical and practical foundation for employing microbubble technology in the remediation of heavy metal ion pollution in soils.