Effect of anions on removal of mercury(II) using fes-supported crossflow ultrafiltration

In this study, crossflow ultrafiltration (CF/UF) was applied to ensure continuous removal of Hg-contacted FeS solids from suspension. The key parameters that are used to evaluate overall performance of the CF/UF treatment system are water flux (permeability or rejection), and variation of water quality (pH, Hg, Fe) in the permeate water over time, as affected by concentrations of anions (Cl⁻, NO₃ ⁻, SO₄ ²⁻). Accordingly, the same water quality parameters were used to evaluate the CF/UF system during desorption tests with thiosulfate solutions. Almost no release of Hg from solids during filtration of Hg-contacted FeS was observed, regardless of the presence of anions. Furthermore, desorption tests with thiosulfate solution showed that the solids retained on the UF membrane were shown to be stable. The surfaces of the solids deposited on the membrane were characterized by SEM/EDS and ATR/FT-IR. The SEM/EDS analysis identified active sites for Hg removal on the membrane surface and ATR/FT-IR analysis exhibited evidence of entire coverage of Hgcontacted FeS on the membrane surface. However, a gradual decrease of sorption capacity for Hg removal by the solids retained on the membrane was observed as additional feed water was applied.