Fe-N co-doped coral-like hollow carbon shell toward boosting peroxymonosulfate activation for efficient degradation of tetracycline: Singlet oxygen-dominated non-radical pathway

Fe-N co-doped coral-like hollow carbon shell (Fe-N-CS) was synthesized via a simply impregnation-pyrolysis method.The Fe-N-CS showed an excellent ability for activating peroxymonosulfate (PMS),which could degrade about 93.74%tetracycline (20 mg/L) in 12 min.The Fe-N-CS/PMS system exhibited a good anti-interference capacity of various pH,inorganic anions,HA and different water qualities.More importantly,the Fe nanoparticles were anchored uniformly in the carbon layer,effectively limiting the metal leaching.The quenching tests and electron spin resonance (ESR) manifested that non-radical singlet oxygen (1O_(2))was the main reactive oxygen species (ROS) for TC degradation.The mechanism study showed that Fe nanoparticles,defect and graphite N played a key role in activating PMS to produce ROS.Moreover,three probable degradation pathways were proposed by using LC-MS measurements.Generally,this work had a new insight for the synthesis of heterogeneous Fe-N-C catalysts in the advanced oxidation process based on PMS.

Superior trichloroethylene removal from water by sulfide-modified nanoscale zero-valent iron/graphene aerogel composite

Sulfide-modified nanoscale zero-valent iron(S-nZVI) is a promising material for removal of organic pollutants from water, but S-nZVI nanoparticles(NPs) easily agglomerate and have poor contact with organic contaminants.Herein, we propose a new S-nZVI/graphene aerogel(S-nZVI/GA) composite which exhibits superior removal capability for trichloroethylene(TCE) from water.Three-dimensional porous graphene aerogel(GA) can improve the efficiency of electron transport, enhance the adsorption of organic pollutants and restrain the agglomeration of the core-shell S-nZVI NPs.The TCE removal rates of Fe S, nZVI, GA and S-nZVI were 27.8%, 42%, 63% and 75% in 2 hr, respectively.Furthermore, TCE was completely removed within 50 min by S-nZVI/GA.The TCE removal rate increased with increasing p H and temperature, and TCE removal followed the pseudo-first-order kinetic model.The results demonstrate the great potential of S-nZVI/GA composite as a low-cost,easily separated and superior monolithic adsorbent for removal of organic pollutants.

Tetracycline removal via adsorption and metal-free catalysis with 3D macroscopic N-doped porous carbon nanosheets:Non-radical mechanism and degradation pathway

Recently,metal-based carbon materials have been verified to be an effective persulfate activator,but secondary pollution caused by metal leaching is inevitable.Hence,a green metalfree 3D macroscopic N-doped porous carbon nanosheets(NPCN)was synthesized successfully.The obtained NPCN showed high adsorption capacity of tetracycline(TC)and excellent persulfate(PS)activation ability,especially when calcined at 700℃(NPCN-700).The maximum adsorption capacity of NPCN-700 was 121.51 mg/g by H-bonds interactions.Moreover,the adsorption process followed pseudo-second-order kinetics model and Langmuir adsorption isotherm.The large specific surface area(365.27 mg/g)and hierarchical porous structure of NPCN-700 reduced the mass transfer resistance and increased the adsorption capacity.About 96.39%of TC was removed after adding PS.The effective adsorption of the catalyst greatly shortened the time for the target organic molecules to migrate to the catalyst.Moreover,the NPCN-700 demonstrated high reusability with the TC removal rate of 80.23%after 4 cycles.Quenching experiment and electron paramagnetic resonance(EPR)test confirmed the non-radical mechanism dominated by ^(1)O_(2).More importantly,the C=O groups,defects and Graphitic N acted as active sites to generate ^(1)O_(2).Correspondingly,electrochemical measurement revealed the direct electron transfer pathway of TC degradation.Finally,multiple degradation intermediates were recognized by the LC-MS measurement and three possible degradation pathways were proposed.Overall,the prepared NPCN had excellent application prospects for removal of antibiotics due to its remarkable adsorption and catalytic degradation capabilities.

The interaction effect between advanced paternal age and paternal obesity is associated with the low implantation rate in couples with unexplained recurrent pregnancy loss

Objective:To explore the roles of advanced paternal age(APA)and abnormal paternal weight on embryo quality and pregnancy outcomes for unexplained recurrent pregnancy loss(uRPL)couples who underwent preimplantation genetic testing for aneuploidies(PGT-A).Methods:This study included 779 uRPL couples who underwent their first PGT-A cycles between 2014 and 2018.Male patients’aging and nutritional status were quantified by paternal age and body mass index(BMI).Routine semen parameters and sperm DNA fragmentation index(DFI)were used to reflect the seminal quality.Blastocyst formation rate and aneuploidy rate were used to reflect the embryo quality.Cycle cancellation rate,implantation rate,pregnancy loss rate,and live birth rate were measured to evaluate the treatment efficiency from IVF.To remove the interference of maternal age,only the women younger than 38 years old were included.After univariate screening,interaction tests were performed in a generalized linear model(GLM)to further examine the effects of paternal age and BMI on each outcome indicator.Results:In the total population(779 cycles),there were no statistical differences in aneuploidy rate,cycle cancellation rate,implantation rate,pregnancy loss rate,and live birth rate,whether stratified by paternal age or paternal BMI.Similar results occurred in the younger men(<40 y.o.,633 cycles).Conversely,among the men with advanced age(≥40 y.o.,146 cycles),there were statistical differences between the three BMI groups in four semen parameters(total sperm number,total motility,progressive motility,and total motile sperm count),implantation rate,and live birth rate.After interaction testing,the results of GLM suggested that the interaction effect between APA and paternal obesity was associated with the low implantation rate of uRPL couples.Conclusions:For the uRPL couples seeking for PGT-A treatment,if the male patients have both advanced age and obesity,their spouses are at higher risks for embryo implantation failure.