Chemical Engineering Journal, Vol.360, 180-189, 2019
Enhanced reduction of organic pollutants by Fe/Cu@Pd ternary metallic nanoparticles under aerobic conditions: Batch and membrane reactor studies
Nanoscale zero-valent iron (nZVI)-based technology has gained a great success in anaerobic groundwater remediation, while the high reactivity of nZVI towards oxygen and protons restricts extending its further application in wastewater treatment under atmospheric conditions. To address this challenge, a novel Fe/Cu@Pd ternary metallic catalyst was synthesized, and its catalytic efficiency with sodium borohydride (NaBH4) for reducing 4-nitrophenol (PNP) under aerobic conditions was examined in batch and continuous-flow modes. In comparison to the reaction in anaerobic condition without adding NaBH4, the rate constants of reduction kinetics for PNP removal in aerobic conditions can be significantly enhanced up to 0.746 min(-1) that is about 25-fold higher. Influence of different background ions on the performance of the catalyst was also systematically investigated, showing that humic acid and nitrate pose relatively strong interference on PNP reduction. The reduction mechanisms were also examined by means of spectroscopic and electrochemical approaches, and the results indicate that enhancement of reduction kinetics is likely due to the fact that catalytic reaction of BH4- by Fe/Cu@Pd nanoparticles can constantly provide electrons and active hydrogen species under aerobic conditions. Finally, a Fe/Cu@Pd based catalytic membrane reactor has been successfully assembled for PNP removal.