In this study, the enhancement on 4-chloronitrobenzene (4-CNB) reduction was investigated in a dual-bioelectrochemical system with the cathode seeded by enriched 4-CNB degradation inoculums. We demonstrated that the biocathode had the ability to promote 4-CNB reduction and avoid more reluctant byproducts production. At room temperature, when initial 4-CNB concentration was 20 mg/L with 0.5 V external voltage, the 4-CNB removal efficiency reached 93.7%, while in the abiotic reactor and anaerobic bioreactor reduction rate were 62.9% and 88.4%, respectively. The 4-CNB was mainly converted to 4-CAN ( para -chloroaniline). Some of the 4-CAN could be dechlorinated and form aniline (AN), which was more degradable by microorganism. The biodiversity was richer based on the result of scanning electron microscope. Results also showed that the present used reactor was feasible to simplify pollutant transformation and improve transformation efficiency compared with the single abiotic cathode and anaerobic reactor . The bioelectrochemical reactor cathode provided a promising condition for pollutants reduction.
4-Chloroaniline (4-CAN) plays an important role in chemical and industrial production. However, it remains a challenge to avoid the hydrogenation of the C–Cl bond in the synthesis process to improve selectivity under high activity conditions. In this study, we in situ fabricated ruthenium nanoparticles (Ru NPs) containing vacancies inserted into porous carbon (Ru@C-2) as a highly efficient catalyst for the catalytic hydrogenation of 4-chloronitrobenzene (4-CNB) with remarkable conversion (99.9%), selectivity (99.9%), and stability. Experiments and theoretical calculations indicate that the appropriate Ru vacancies affect the charge distribution of the Ru@C-2 catalyst, promote the electron transfer between the Ru metal and support, and increase the active sites of the Ru metal, thus facilitating the adsorption of 4-CNB and the desorption of 4-CAN to improve the activity and stability of the catalyst. This study can provide some enlightenment for the development of new 4-CNB hydrogenation catalysts.