The visible light photo-Fenton-like catalytic performance of BiFeO3 nanoparticles was investigated using Methyl Violet (MV), Rhodamine B (RhB) and phenol as probes. Under optimum conditions, the pseudo first-order rate constant (k) was determined to be 2.21×10-2, 5.56×10-2 and 2.01×10-2 min-1 for the degradation of MV (30 μmol/L), RhB (10 μmol/L) and phenol (3 mmol/L), respectively, in the BiFeO3-H2O2-visible light (Vis) system. The introduction of visible light irradiation increased the k values of MV, RhB and phenol degradation 3.47, 1.95 and 2.07 times in comparison with those in dark. Generally, the k values in the BiFeO3-H2O2-Vis system were accelerated by increasing BiFeO3 load and H2O2 concentration, but decreased with increasing initial pollutant concentration. To further enhance the degradation of pollutants at high concentrations, BiFeO3 was modified with the addition of surface modifiers. The addition of ethylenediamineteraacetic acid (EDTA, 0.4 mmol/L) increased the k value of MV degradation (60 μmol/L) from 1.01×10-2 min-1 in the BiFeO3-H2O2-Vis system to 1.30 min-1 in the EDTA-BiFeO3-H2O2-Vis system by a factor of 128. This suggests that in situ surface modification can enable BiFeO3 nano-particles to be a promising visible light photo-Fenton-like catalyst for the degradation of organic pollutants. 相似文献
Water treatment is the key to coping with the conflict between people’s increasing demand for water and the world-wide water shortage. Owing to their unique and tunable structural, physical, and chemical properties, carbon nanotubes (CNTs) have exhibited great potentials in water treatment. This review makes an attempt to provide an overview of potential solutions to various environmental challenges by using CNTs as adsorbents, catalysts or catalyst support, membranes, and electrodes. The merits of incorporating CNT to conventional water-treatment material are emphasized, and the remaining challenges are discussed. 相似文献
A titanium dioxide film on a graphite substrate was synthesized by chemical bath deposition from TiCl4 as precursor and with the surfactant cetyl trimethyl ammonium bromide as a linking and assembling agent. Silver was loaded on the TiO2 film by electrodeposition at 0.025?A. Water contaminated with Escherichia coli was disinfected under sunlight irradiation by photolysis (Lys), photocatalysis (PC), photoelectrocatalysis (PEC), and electrocatalysis (EC). The highest rate constant, k, was achieved with EC; k was 5.1?×?10?2 colony forming units (CFU) mL?1?min?1. However, auto-oxidation of Ag occurred during EC and PEC. Meanwhile, the rate constant of disinfection by means of PC was lower than EC and PEC, and k was 3.82?×?10?2 CFU?mL?1?min?1. Nevertheless, the auto-oxidation of Ag in the Ag–TiO2/graphite tablet did not occur during the disinfection process. 相似文献
Nitrous oxide (N2O), a potent greenhouse gas, is emitted during nitrogen removal in wastewater treatment, significantly contributing to greenhouse effect. Nitrogen removal generally involves nitrification and denitrification catalyzed by specific enzymes. N2O production and consumption vary considerably in response to specific enzyme-catalyzed nitrogen imbalances, but the mechanisms are not yet completely understood. Studying the regulation of related enzymes’ activity is essential to minimize N2O emissions during wastewater treatment. This paper aims to review the poorly understood related enzymes that most commonly involved in producing and consuming N2O in terms of their nature, structure and catalytic mechanisms. The pathways of N2O emission during wastewater treatment are briefly introduced. The key environmental factors influencing N2O emission through regulatory enzymes are summarized and the enzyme-based mechanisms are revealed. Several enzymebased techniques for mitigating N2O emissions directly or indirectly are proposed. Finally, areas for further research on N2O release during wastewater treatment are discussed.
