(54ar) Immobilization of Sulfur-Oxidizing Bacterium, Thioalkalivibrio Sp. D301 on Magnetic Nanaoparticles and Biodesulfurization

There is an urgent need to develop desulfurization methods for halo-alkaline wastewater. Thialkalivibrio sp. D301, an obligatory chemolithoautotrophic, haloalkaliphilic, sulfur-oxidizing bacterium, was used in the removal of sulfide in wastewater. We developed a process to immobilize D301 cells by using superparamagnetic Fe₃O₄ nanoparticles (NPs) under halo-alkaline conditions. Fe₃O₄ NPs were synthesized by coprecipitation of ferric and ferrous salts in the presence of N₂ gas. TEM image shows the spherical shape of Fe₃O₄ NPs with an average diameter of 10 to 15 nm. The particles had superparamagnetic properties. The saturation magnetization (δ_s) of the Fe₃O₄ NPs was 73.985 emu g^−1 with zero remanence and coercivity. Analysis of zeta potentials and hydraulic diameters showed that the Fe₃O₄ NPs and bacterial cells interact mainly through the nano-size effect. The NPs-coated cells have the same sulfur oxidization activity as that of free cells. Experiment results showed that the immobilized cells still retained >90% of their sulfur oxidization activity after six times of reuse. The cells coated with Fe₃O₄ NPs did not interact through electrostatic attraction. The mechanism of NPs adsorption mainly involved the nano-size effect. Magnetic immobilization is a convenient technique for HA-SOB immobilization under halo-alkaline conditions and is a promising technology for large-scale industrial applications.