Degradation of o-chloronitrobenzene as the sole carbon and nitrogen sources by Pseudomonas putida OCNB-1

A bacterial strain that utilized o-chloronitrobenzene （o-CNB） as the sole carbon, nitrogen and energy sources was isolated from an activated sludge collected from an industrial waste treatment plant. It was identified as Pseudomonas putida based on its morphology, physiological, and biochemical characteristics with an automatic biometrical system and the 16S rRNA sequence analysis. Microcosm study showed that the biodegradation of o-CNB was optimized at culture medium pH 8.0 and 32℃. At these conditions, the strain degraded 85% of o-CNB at a starting concentration of 1.1 mmol/L in 42 h. o-Chloroaniline was identified as the major metabolite with high performance liquid chromatography （HPLC） and gas chromatography-mass spectrometry （GC-MS）. The study showed that o-CNB degradation by Pseudomonas putida OCNB-1 was initiated by aniline dioxyenase, nitrobenzene reductase and catechol-l,2- dioxygenase.

Electrochemical Degradation of o-Chloronitrobenzene by Three-dimensional Electrodes

Degradation of o-chloronitrobenzene wastewater was experimentally investigated at a three-dimensional electrode（TDE） with granular activated carbon as the particle electrode, graphite as the anode, and stainless steel plate as the cathode. The kinetic model of o-chloronitrobenzene degradation was studied, and the effects of pH, electrolysis time, particle electrode, electrolyte concentration, and initial concentration of the solution on degradation efficiency were investigated to determine the optimal operating conditions. The degradation of o-chloronitrobenzene by oxidation at the TDE was monitored by chemical oxygen demand（COD） measurements, UV-Vis absorption, and high performance liquid chromatography（HPLC）. COD degradation by electrochemical degradation followed pseudo-first order kinetics with respect to the concentration of o-chloronitrobenzene solutions. Optimal reaction conditions included 15 g of activated carbon as the particle electrode, 400 mg/L o-chloronitrobenzene solution containing 0.10 mol/L Na2SO4, pH=3, and 60 min of electrolysis. The UV-Vis absorption spectra and HPLC results illustrate that the benzene ring in o-chloronitrobenzene was rapidly broken down to form aliphatic substances through electrochemical degradation. COD degradation was approximately 98.5% at optimal conditions.

Behavior of adsorbed diphenyl-sulfide on the Pd/C catalyst for o-chloronitrobenzene hydrogenation

A series of diphenyl-sulfide （Ph2S）-immobilized Pd/C catalysts （Pd-Ph2Scx）/C） were prepared using the wetness-impregnation and immobilization method. Pd-Ph2S（x）/C catalysts employed for the hydro- genation of o-chloronitrobenzene showed very high selectivity. The structure of Pd-Ph2Scx）/C with different molar ratio of ligand （x-values） was characterized by XPS and TG-DSC-MS. The results suggest a ＂saturated＂ surface ratio of Ph2S/Pd （about 0.3） was formed on the Pd-Ph2S（x）[C catalysts surface. The Ph2S immobilized on the Pd particle is quite stable, and the desorption of Ph2S or dissociative loss of phenyl group was only found at temperatures above 500 K. The possible catalytic mechanism of the Pd-Ph2S（x）/C catalyst was also discussed.