Enhanced sulfate reduction by Citrobacter sp. coated with Fe 3 O 4 /SiO 2 magnetic nanoparticles

A sulfate-reducing Citrobacter strain was isolated and coated with Fe 3 O 4 /SiO 2 magnetic nanoparticles (MNPs) to enhance sulfate reduction. Biolog analysis showed that it utilizes a broad range of electron donors. The findings also showed that this bacteria strain is a facultative anaerobe and can completely reduce 12 mM of sulfate to sulfide in 7 days under anaerobic conditions. Moreover, sulfate reduction was enhanced by 79% under optimized conditions. Different SiO 2 wrap-ratios of the MNPs attached to the cell surface were studied to optimize the sulfate reduction: the surface of cells coated with 300% silica wrap-ratio MNPs showed the highest stability and increased desulfurization batch time, with a 450% increase in sulfate reduction in comparison with uncoated cells cultivated in anaerobic conditions.