Kinetics of Hexavalent Chromium Adsorption and Reduction by Living Cells of the Marine Bacterium Bacillus cereus
2025
Jittima Charoenpanich | Wachiraphorn Cherdchoo | Jutamas Pantab | Jariya Supakrit
This study identified Bacillus cereus, an efficient Cr(VI) bioreducer, isolated from marine sediment in Thailand. Batch experiments verified the complete removal of 25 mg L-1 Cr(VI) from synthetic wastewater (pH 7.0) after 6 days at 37 °C, 50 rpm, and a biomass concentration of 25% (v/v) culture inoculum. The Freundlich isotherm model demonstrated the best correlation with the Cr(VI) adsorption equilibrium data in the 25–100 mg L-1 concentration range (R2 = 0.9831). Kinetic analyses indicated that the removal of Cr(VI) by living B. cereus followed a pseudo-second-order adsorption model (R2 = 0.9875) and a pseudo-second-order reduction model (R2 = 0.9807). The adsorption rate can be accurately characterized via the intraparticle diffusion model and a Boyd plot. This bacterium can remove Cr(VI) in four steps: (1) migration of Cr(VI) from the fluid into the cell membrane; (2) chemical interaction of Cr(VI) with carbon and oxygen functional groups present on the cell surface; (3) multilayer adsorption and diffusion of chromium ions from the cell surface to the internal pores of the cellular particles; and (4) reduction of chromium ions to other forms. This research highlights the potential application of B. cereus in mitigating Cr(VI) environmental issues.
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