Co-Removal of Cadmium(Ii) and Arsenic(Iii) by Ferrihydrite and Bacillus Pseudomycoides Cr-24 on Biochar

Abstract

Iron-based materials have excellent adsorption properties for heavy metals through precipitation and oxidation mechanisms. Iron-modified biochar loaded with Bacillus sp. was investigated based on four types of materials (BC, B@BC, F@BC, and BF@BC). They were synthesized to remove co-existence of Cd(II) and As(III) in solutions. It showed that CR-24 significantly improved the specific surface area and Si-containing functional groups. Specifically, B@BC had superior adsorption capacity for Cd(II). The surface of F@BC was enriched in Fe-containing functional groups, which significantly improved As(III) adsorption. The BF@BC (with coexistence of iron minerals and CR-24) enhanced the adsorption and precipitation of Cd(II) and As(III). It also exhibited the potential to promote the oxidation of As(III) by producing a large number of hydroxyl radicals (·OH). After Langmuir model fitting, the maximum saturated adsorption capacity of BF@BC for Cd(II) and As(III) was 15.49 and 8.41 mg·g-1, which was increased by 52.47% and 299%, respectively.

Keywords: iron-modified biochar, heavy metals, Bacillus sp., coexistence, oxidation of As(III)