Cobalt-loaded carbon nanotubes boosted aerobic ciprofloxacin transformation driven by sulfide:A comprehensive mechanism investigation

Sulfide oxidation under aerobic conditions can produce active oxygen for the transformation of organic pollutants in aquatic environments.However,the catalytic performance of transition metal-supported carbon material on this process is poor understood.This study found that Co-loaded carbon nanotubes(CNTs)was able to realize the efficient aerobic transformation of antibiotic ciprofloxacin(CIP)by sulfide,with the pseudo-first order reaction rate constant improved from 0.013 h^(-1)without catalyst to 0.44–0.71 h^(-1)with 100 mg/L Co-loaded CNTs.Singlet oxygen(^(1)O_(2))was the main active specie playing key roles in the process of CIP aerobic transformation with presence of Co-loaded CNTs.Mechanism studies indicated that the excellent electron transfer ability of Co-loaded CNTs might play an important role to promote the electron transfer and facilitate the formation of intermediate H_(2)O_(2)and^(1)O_(2).Additionally,the Co-loaded CNTs/sulfide system effectively reduced the acute toxicity of organic pollutant,and Co-loaded CNTs showed remarkable cycling stability and negligible leaching.This study gives a better understanding for the Co-loaded CNTs mediated aerobic antibiotics transformation by sulfide,and provide a reference for the application of Co-loaded carbon materials on organics aerobic transformation by sulfide.

Impacts of reducing air pollutants and CO_(2) emissions in urban road transport through 2035 in Chongqing, China

The road transport sector in megacities is confronted with pressing local air pollution and carbon dioxide(CO_(2))control issues.To determine effective policy instruments for saving energy and the co-control of air pollutants and CO_(2),several mainstream measures were examined and compared in Chongqing's road transport sector from 2017 to 2035.An integration assessment framework was developed by combining the Long-range Energy Alternatives Planning(LEAP)system and a set of quantitative methods for evaluating the co-benefits of emission reductions(including the air pollutant equivalent(APeq),cocontrol coordinate system,and pollutant reduction cross-elasticity(Elsa/b)).Results showed that the shifting transportation modes scenario presented the most significant potential for energy-saving and emission reductions,reducing energy use by 30.9%and air pollutants and CO_(2) emissions by approximately 27e32%compared with the business as usual(BAU)scenario in 2035.The improving energy efficiency scenario also provided significant co-benefits for reducing air pollutants and CO_(2) emissions.Nevertheless,the promoting alternative fuel scenario may increase fine particulate matter(PM2.5)emissions by 2.2%compared to BAU in 2035 under the cleanness of regional electricity in 2017.Our findings suggest that the shifting transportation modes were effective measures to reduce air pollutants and CO_(2) in the short term synergistically,and highlighted the importance of cleaner electricity generation to develop electric vehicles in the medium and long term.

Nitrogen-doped pyrogenic carbonaceous matter facilitates azo dye decolorization by sulfide: The important role of graphitic nitrogen

Pyrogenic carbonaceous matter(PCM) catalyzes azo dye decolorization by sulfide, but the nitrogen doping catalytic mechanisms are poorly understood. In this study, we found that stagnate time of azo dye methyl orange(MO) decolorization was reduced to 0.54-18.28 min in the presence of various nitrogen-doped graphenes(NGs), remarkably lower compared to graphene itself. Particularly, graphitic nitrogen played a critical role in NGs-catalyzed MO decolorization by sulfide. Gas chromatography-mass spectrometry and in-situ surface Raman analysis demonstrated that doping nitrogen, especially graphite one facilitated reactive intermediate polysulfides formation. This is attributed to the improved electron conductivity through graphitic nitrogen doping, and the enhanced interactions between sulfide and carbon atoms bonded to graphitic nitrogen. This study not only provides a better understanding of PCM impact on transformations and fates of organic pollutants in natural environments, but also offer a new regulation strategy for more efficient wastewater treatment processes in PCM-catalyzed engineering systems.