Reduction of Fe(III)EDTA(-) in a NO(x) scrubbing solution by magnetic Fe3O4-chitosan microspheres immobilized mixed culture of iron-reducing bacteria.

Magnetic Fe(3)O(4)-chitosan microspheres were prepared by co-precipitating of Fe(2+) and Fe(3+) 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 (NO(x)) 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 S(2-), the potential inhibition compounds in the scrubber solution, on the reduction of Fe(III)EDTA(-) by the immobilized and free bacteria were also studied.