Mechanism of enhanced Sb(V) removal from aqueous solution using chemically modified aerobic granules

Abstract

Sb(V) removal using Fe-modified aerobic granules was investigated. Increasing the biomass dosage improved the Sb(V) removal rate, but lowered the adsorption quantity; the optimal biomass concentration was 20. g/L (wet basis). Adsorption equilibrium was obtained at 2. h at 175. rpm; the adsorption quantity was 36.6. mg/g. NaCl and other salts inhibited Sb(V) adsorption on Fe-modified granules, and the mechanism possibly lied more with the anions. The adsorption isotherms were evaluated using the Langmuir, Freundlich, and Temkin models. The Langmuir model best described the adsorption process, and gave a maximum monolayer adsorption quantity of 125. mg/g. The £_. H value for adsorption was 16.1. kJ/mol, indicating endothermicity, and the negative £_. G values at various temperatures suggested spontaneous adsorption. Outer-sphere and inner-sphere complexations were involved in Sb(V) adsorption. ? 2014 Elsevier B.V.