Fe(II) bio-oxidation mediates red mud transformations to form Fe(III)/Al (hydr)oxide adsorbent for efficient As(V) removal under acidic conditions

Acidic wastewater rich in arsenic (As) is one of the most hazardous types liquid waste and has caused severe environmental pollution over past few decades due to a lack cost-effective environment-friendly disposal technologies. Here, new strategy for efficient immobilization As(V) under acidic conditions presented. The approach uses Fe(II) bio-oxidation by acidophilic bacterium Sulfobacillus (Sb.) thermosulfidooxidans transform red mud into low-cost Fe(III)/Al (hydr)oxide adsorbent removal. mechanisms formation subsequent adsorption As onto its surface were investigated, together with relationship between structure efficiency. [Fe(II)]ini greatly affected growth Sb. thermosulfidooxidans, Fe/Al speciation, adsorbent, as well removal capacity. aluminosilicates RM provided numerous sites Fe(III) adsorption, inhibiting transformation amorphous (hydr)oxides crystalline minerals. newly formed Fe(OH)3 schwertmannite played dominant role immobilization. more minerals, an excess (2 ? 4 g/L), resulted significant decrease capacity (reduce ratio: 29.3–53.5%). bio-synthesized 1 g/L showed highest efficiency (89.9 mg/g; at pH 2.0), which was significantly higher than that original same (5.7 mg/g). process followed pseudo-second-order kinetic Langmuir isotherm models.