Antimony(III) removal by biogenic manganese oxides formed by Pseudomonas aeruginosa PA-1: kinetics and mechanisms

In this study, Pseudomonas aeruginosa PA-1, a manganese-oxidizing bacterium screened from the soil at a manganese mining area, was found to be tolerated to Sb(III) stress during the Mn(II) oxidation, and the generated biological manganese oxide (BMO) outperformed the identical type of Abiotic-MnOX in terms of oxidation and adsorption of Sb(III). Adsorption kinetics and isotherm experiments indicated that Sb(III) was primarily adsorbed through chemisorption and multilayer adsorption on BMO; the maximum adsorption capacity of BMO was 143.15 mg center dot g(-1). Removal kinetic studies showed that the Sb(III) removal efficiency by BMO was 72.38-95.71% after 15 min, and it could be up to 96.32-98.31% after 480 min. The removal procedure could be divided into two stages, fast (within 15 min) and slow (15 similar to 480 min), both of which exhibited first-order kinetic behavior. Dynamic fitting in two steps revealed that the removal speed correlated to the level of dissolved Sb(III) with low Sb(III) concentrations, but with the initial concentration being high, the removal speed rate was independent of dissolved Sb(III). During the whole process, the Sb(III) removal speed by BMO was also higher than that by the Abiotic-MnOX. Combining multiple spectroscopic techniques revealed that Sb(V) was generated through the Sb(III) oxidation by BMO and replacing surface metal hydroxyl groups to form the complex internal Mn-O(H)-Sb(V) or generating stable Mn(II)-antimonate precipitates on the surface. In addition, microbial metabolites, including tryptophan and humus, in BMO may be complex with Sb(III) and Sb(V) to achieve the treatment of Sb(III). This research investigates the factors and mechanisms influencing the adsorption and removal of Sb(III) by BMO, which could aid in its future engineering applications for the BMO.

Automated summary

In this study, a manganese-oxidizing bacterium, Pseudomonas aeruginosa PA-1, was found to tolerate Sb(III) stress during Mn(II) oxidation, and the resulting biological manganese oxide (BMO) showed superior oxidation and adsorption of Sb(III) compared to Abiotic-MnOX. The adsorption experiments indicated that Sb(III) primarily adsorbed onto BMO through chemisorption and multilayer adsorption, with a maximum adsorption capacity of 143.15 mg center dot g(-1). The removal kinetic studies showed that BMO achieved a removal efficiency of 72.38-95.71% after 15 min, and up to 96.32-98.31% after 480 min, with first-order kinetic behavior observed in both fast (within 15 min) and slow (15 to 480 min) removal stages. The research also revealed the mechanisms of Sb(III) oxidation by BMO and the formation of Sb(V) through surface reactions.