Extraction of heavy metals and ammonium from waters by unsaturated fatty acids and their soaps

摘要

The process including heavy metals and ammonium extraction from waters by an extraction medium based on unsaturated fatty acids and their soaps, up-concentration of the extracted metals, and regeneration of the extraction medium was investigated. The process corresponds to current hydroxides-precipitating, coagulation and biotreatment processes. The two synergistically effective ways are described: the basic process with the pretreatment of feed water by sodium or calcium hydroxide and extraction with unsaturated fatty acids, and the advanced process exploiting the extraction through sodium and/or calcium unsaturated fatty acids soaps. Oleine as a commercially available extraction medium was used. High bonding capacity and metals removal efficiency, fast kinetics and selectivity for the extraction process, and the self-adjustment of the pH value after the extraction process, as well as the high up-concentration of the metals salts limiting to saturated solutions, and the complete regeneration of the extraction medium were reached. Heavy metals hydroxides precipitation behaviour was investigated. Chemical and hydrophobisation metals-bonding mechanisms for the extraction process were observed. Regeneration and up-concentration behaviour, Oleine stability and organics residues in the water phases were investigated.