Study on Extraction Separation of Thioarsenite Acid in Alkaline Solution by [Formula: see text]-Type Tri-n-Octylmethyl-Ammonium Chloride

To overcome the problem of arsenic separation and enrichment from an alkaline leaching solution in arsenic-containing dust, a [Formula: see text]-type tri-n-octylmethyl-ammonium chloride (TOMAC) method for extracting thioarsenite is proposed in this paper. Considering an alkaline leaching solution as the research object, after vulcanization pretreatment, TOMAC transformation and organic phase saturated extraction capacity were measured, and the extraction mechanism was preliminarily studied. First, Cl(−)-type quaternary ammonium salt was effectively transformed to [Formula: see text]-type by treating organic phase with saturated NaHCO(3five) times. TOMAC was effectively transformed from [Formula: see text] to [Formula: see text] type by alkaline washing with 1.0 mol/l NaOH solution; this washing was repeated thrice. Thereafter, the effects of organic phase composition, phase ratio, extraction time, and temperature on the extraction and separation of arsenic were investigated. The results show that under the conditions of 30% [Formula: see text]-type TOMAC + 15% sec-octanol + 55% sulfonated kerosene, V(O)/V(A) = 1/1, and 5 min extraction at room temperature, the single-stage extraction rate of As(III) is 85.2%. The As(III) concentration in raffinate can be reduced to less than 1.33 × 10(−3) mol/l by four-stage countercurrent extraction, and the extraction rate of As(III) can exceed 98.4%.