A composite system of Staphylococcus saprophyticus JJ-1 and its synthesized Pd nanoparticles for the reduction of o-chloronitrobenzene

Reduction of nitrobenzene by bacteria and its synthesized nanoparticles provides a reliable method for treating organic pollutants in wastewater. Bio-Pd nanoparticles were synthesized by the reduction of sodium chloropalladate using S. saprophyticus JJ-1. The morphology, size and crystal form of the synthesized Bio-Pd nanoparticles were analyzed by a series of characterization techniques. o-chloronitrobenzene (2-CNB) was reduced using a composite system of S. saprophyticus JJ-1 and its synthesized Bio-Pd nanoparticles, and the reduction products and reduction pathways were analyzed. The results showed that S. saprophyticus JJ-1 reduced the palladium salt quickly and formed Bio-Pd nanoparticles subsequently. The “S. Saprophyticus JJ-1/Bio-Pd” system demonstrated excellent catalytic reduction performance for o-chloronitrobenzene. Gas chromatography-mass spectrometry (GC-MS) analysis showed that the reduction products of o-chloronitrobenzene were o-chloroaniline, nitrobenzene and aniline, indicating that the system can achieve nitro reduction and dechlorination simultaneously. Quantitative analysis of o-chloronitrobenzene and its products by high performance liquid chromatography (HPLC) showed that o-chloroaniline and nitrobenzene were intermediate products, and aniline was the final product. In addition, results showed that the optimal concentration of sodium chloropalladate in this system is 0.2 mmol/L, and the upper limit of o-chloronitrobenzene should not exceed 0.6 mmol/L. S. saprophyticus JJ-1 can rapidly synthesize Bio-Pd NPs, and has good reduction and conversion effects on o-chloronitrobenzene (2-CNB) under a synergistic catalytic system.