Water Decontamination of Sulfide Flotation Effluents: Removal of Sodium Diethyl Dithiophosphate (Sodium Aerofloat) Using Thermochemically Modified Activated Carbon

Mining flotation effluents may contain residual collectors that pose risks to aquatic environments when discharged without adequate treatment. Among these compounds, sodium diethyl dithiophosphate (SDE DTP) is of particular concern due to its persistence and potential ecotoxicological effects. This study evaluated the removal of SDE DTP from aqueous media using commercial activated carbon and thermochemically modified activated carbon prepared through nitric acid oxidation and urea treatment. Batch adsorption experiments were conducted using synthetic SDE DTP solutions and a laboratory-generated flotation effluent obtained from a copper sulfide ore containing approximately 0.5 wt.% Cu. A UV–visible spectrophotometric method was applied for the quantification of SDE DTP in both systems. The effects of adsorbent dosage, solution pH, and surface modification were investigated. Adsorption performance increased with activated carbon dosage and was strongly influenced by pH. Thermochemical modification significantly enhanced adsorption performance, increasing SDE DTP removal from 40% for unmodified carbon to 93% for the modified material. The modified adsorbent also maintained high efficiency in real flotation effluent, achieving 88% removal despite competing dissolved species. These results demonstrate that thermochemically modified activated carbon is a promising functional material for treating flotation effluents contaminated with dithiophosphate collectors.