热还原法制备g-C_(3)N_(4)/高岭石复合材料及其光/过硫酸盐协同催化性能

Photocatalysis Coupled with Persulfate Oxidation over Nitrogen Vacancies Modified g-C_(3)N_(4)/kaolinite Composite for Highly Efficient Removal of Bisphenol A

采用热还原法制备了一种具有氮空位的石墨相氮化碳(g-C_(3)N_(4))/高岭石复合材料,利用扫描电子显微镜、X射线衍射、红外光谱、紫外-可见分光光度法、X射线光电子能谱仪等手段对复合材料进行表征,并以双酚A(BPA)为目标污染物,系统考察了复合材料在可见光/过硫酸盐催化降解体系中的催化活性。结果表明:优化条件下制备的样品NGK-10:1对BPA的降解效率最高,分别为g-C_(3)N_(4)和氮空位g-C_(3)N_(4)的9.98和5.72倍,一方面归因于较大的比表面积和孔体积为污染物吸附与降解提供了更多的反应活性位点,另一方面氮空位的形成既可以作为光生电子的捕获中心,提升光生载流子的迁移和分离效率,同时也为PMS的高效活化提供了电子,促进了SO_4~(·-)和·OH的形成,进而实现对BPA降解过程的协同强化;自由基淬灭实验发现非活性自由基起到主要氧化降解作用。

A new type of graphite carbon nitride(g-C_(3)N_(4))/kaolinite composites with abundant nitrogen vacancies was prepared by using a facile thermal reduction method.The composites were characterized by using scanning electron microscopy(SEM),X-ray diffraction(XRD),Fourier transform infrared spectrometer(FTIR),UV-Vis absorption spectroscopy and X-ray photoelectron spectrometry(XPS).Bisphenol A(BPA)was used as the target pollutant to evaluate the catalytic activity of the composites through photocatalysis coupled with persulfate oxidation.It was observed that the degradation rate of NGK-10:1 was 9.98 and 5.72 times higher than those of g-C_(3)N_(4) and nitrogen vacancies modified g-C_(3)N_(4),respectively.On one hand,the large specific surface area and high porosity provided with more reactive site and hence promoted the adsorption capacity of pollutants on the composites.On the other hand,the formation of nitrogen vacancies acted as the photo-generated electron trap centers and thus inhibited the recombination of electron-hole pairs.In addition,there would be more electrons to activate PMS,thus promoting the formation of SO_(4)•−and·OH.Quenching experimental results showed that the non-radical pathway played the major role in the removal of BPA.