Active sites and reaction mechanism for N-doped carbocatalysis of phenol removal

Heteroatom-doping of carbocatalysts has been a powerful strategy to remarkably enhance the catalytic performance.Herein,the underlying nature of N promotional effects on peroxymonosulfate(PMS)activation for phenol removal is understood by combining kinetics analysis with multiple techniques.A strategy using mixed acid oxidation of carbon nanotube(CNT)followed by NH3 treatment is employed to yield a series of catalysts with different N-doping contents but similar fraction of sp^(2)-hybridized carbon and defective degree,endowing with a chance to discriminate the dominant N-containing active sites.The multi-sites kinetics analysis suggests the graphitic N-containing sites as the dominant active sites.The mechanism of the surface-bound reactive species is also discriminated as the dominant reaction mechanism.The insights reported here could provide the methodology to fundamentally understand the heteroatom-doping effects of carbocatalysis.

Hybrid peroxi-coagulation/ozonation process for highly efficient removal of organic contaminants

Aromatic compounds such as phenols presented widely in coal chemical industry wastewater(CCW)render the treatment facing great challenge due to their biorefractory characteristics and potential risks to the environment and human health.Ozone-based advanced oxidation processes show promising for these pollutants removal,but the mineralization via ozonation alone is unsatisfactory and not cost-effective.Herein,a hybrid peroxi-coagulation/ozonation process(denoted as PCO)was developed using sacrificial iron plate as an anode and carbon black modified carbon felt as cathode in the presence of ozonation.An enhanced phenol removal of∼100%within 20 min and phenol mineralization of∼80%within 60 min were achieved with a low energy consumption of 0.35 kWh/g TOC.In this novel process,synergistic effect between ozonation and peroxi-coagulation was observed,and beside O_(3) direct oxidation,peroxone played a dominant role for phenol removal.In the PCO process,the hydrolyzed Fe species enhanced the generation of reactive oxygen species(ROS),while•OH was dominantly responsible for pollutant degradation.This process also illustrated high resistance to high ionic strength and better performance for TOC removal in real wastewater when compared with ozonation and peroxi-coagulation process.Therefore,this process is more cost-effective,being very promising for CCW treatment.

Tuning surface sites to boost photocatalytic degradation of phenol and ciprofloxacin

There is an urgent demand for tuning the selectivity and activity of the photocatalysts to remove coexistent pollutants simultaneously.Herein,we introduced the surficial activity sites into the bismuth oxybromide(Bi OBr),including the Bi/Bi-O defects and hetero Cu atoms,and then the higher photocatalytic activity and selectivity of BiOBr were realized for degradation phenol and ciprofloxacin(CIP).It can be found that the Bi/Bi-O defects played more important role in enhancing the photocatalytic activity for degradation of phenol,while the Cu atoms significantly improved the photocatalytic activity for removing CIP.Moreover,the heterogeneous Cu atoms as the activity sites excited the reaction between phenol and CIP even under dark condition and were beneficial for synchronously removing phenol and CIP.This work provides a feasible way for BiOX photocatalyst to remove co-existent pollutants and may have a practical application.