NC-PC锚定微量Fe活化PMS降解水中2,4-二氯苯氧乙酸

NC-PC anchors trace Fe to activate PMS to degrade 2,4-dichlorophenoxyacetic acid in water

采用分步热分解法制备了NC-PC(三维多孔碳材料)锚定的微量Fe基催化剂,用于活化过一硫酸盐(PMS)氧化降解水中2,4-二氯苯氧乙酸(2,4-D).采用透射电子显微镜(TEM)、高精度比表面积仪(BET)、X射线光电子能谱分析(XPS)和电感耦合等离子体发射光谱分析(ICP)对催化剂进行表征.考察了不同金属、制备方法、催化剂投加量、PMS投加量、初始pH值以及水中不同阴离子Cl^(-)、NO_(3)^(-)、HCO_(3)-)对2,4-D降解的影响.结果表明,通过热分解法合成的Fe-NC-PC对2,4-D具有更好的降解效果,当2,4-D初始浓度为0.1mmol/L,初始pH=3.4,催化剂投加量0.15g/L,PMS浓度0.7mmol/L时,反应20min内2,4-D的去除率可达91%.随着催化剂投加量、PMS投加量的提高,2,4-D的降解效果提高;随着初始pH值的提高,2,4-D的降解效率逐渐降低;水中不同阴离子Cl^(-)、NO_(3)^(-)、HCO_(3)^(-)和腐殖酸(HA)对2,4-D的降解有轻微的抑制作用.通过自由基淬灭实验、EPR测试以及XPS分析了反应的主要活性物种和反应机理,发现材料制备过程中形成的Fe-Nx是主要的反应活性位,能够有效的活化PMS降解水中2,4-D,1O2在2,4-D的降解过程中起到主要作用.

A small amount of Fe-based catalyst anchored by NC-PC(three-dimensional porous carbon material)was prepared by a step-by-step thermal decomposition method,which was used to activate permonosulfate(PMS)to oxidize and degrade 2,4-dichlorophenoxyacetic acid(2,4-D)in water.The catalysts were characterized by transmission electron microscopy(TEM),fully automatic rapid surface measurement(BET),X-ray photoelectron spectroscopy(XPS)and inductively coupled plasma emission spectroscopy(ICP).The effects of different metals,preparation methods,catalyst dosage,PMS dosage,initial pH,and different anionsCl^(-),NO_(3)^(-),HCO_(3)^(-)on the degradation of 2,4-D were investigated.Fe-NC-PC synthesized by thermal decomposition method has a better degradation effect on 2,4-D,when the initial concentration of 2,4-D was 0.1mmol/L,the initial pH=3.4,the catalyst was added When the amount was 0.15g/L and the PMS concentration was 0.7mmol/L,the 2,4-D removal rate can reach 91%within 20 minutes of reaction.With the increase of the dosage of catalyst and PMS,the degradation effect of 2,4-D increased;with the increase of initial pH,the degradation efficiency of 2,4-D gradually decreased;different anions in water Cl^(-),NO_(3)^(-),HCO_(3)^(-)and humic acid(HA)has a slight inhibitory effect on the degradation of 2,4-D.Through radical quenching experiment,EPR test and XPS analysis of the main active species and reaction mechanism of the reaction,it was found that Fe-Nx formed during the material preparation process was the main reactive site,which can effectively activate PMS to degrade 2,4-D in water,1O2 plays an important role in the degradation of 2,4-D.