Reduction of Fe(III)EDTA− in a NOx scrubbing solution by magnetic Fe3O4–chitosan microspheres immobilized mixed culture of iron-reducing bacteria

Magnetic Fe3O4–chitosan microspheres were prepared by co-precipitating of Fe2+ and Fe3+ ions with NaOH in the presence of chitosan. The saturated magnetization of the resulting material was 20.0 emu/g. Then these magnetic microspheres were employed to immobilize iron-reducing bacteria to improve the biological reduction of Fe(III)EDTA−, which was one of the key steps in nitrogen oxides (NOx) removal by the integrated chemical absorption–biological reduction process. The immobilized bacteria performed well on Fe(III)EDTA− reduction than free bacteria, even under unfavorable pH and temperatures. Furthermore, the effects of NO 2 - , NO 3 - , SO 3 - , and S2−, the potential inhibition compounds in the scrubber solution, on the reduction of Fe(III)EDTA− by the immobilized and free bacteria were also studied.