不同源胡敏酸的表征及其对磺胺嘧啶光降解的影响

Characterization of humic acid from different sources and its effection photodegradation of sulfadiazine

以国际腐殖酸协会(IHSS)推荐的方法为基础,对四川省绵阳市青义镇泥炭地、水稻田及凋落物覆盖土层中的胡敏酸(HA)进行提取纯化.通过元素组成、紫外-可见光谱、傅里叶红外光谱及三维荧光光谱对各HA样品的结构特性进行对比分析,并探讨各HA对磺胺嘧啶光降解行为的影响.结果表明:泥炭地HA(NTHA)、水稻田HA(SDHA)、凋落物覆盖土HA(LYHA)及市售商品HA(SPHA)均主要由C、H、O、N 4种元素构成,芳香性大小为SPHA>NTHA>LYHA>SDHA;与提取的HA相比,SPHA含有更多的含氮类、芳香类、脂类化合物及含氧官能团,腐殖化程度高,可能含有较多的光活性基团;磺胺嘧啶(SDZ)在黑暗条件下表现出良好的稳定性,而紫外光照条件下发生了缓慢降解,光降解过程符合一级反应动力学;添加不同来源HA后,各体系SDZ的光降解速率均大于纯水溶液,且HA表现出的促进作用大小为SPHA>SDHA>NTHA>LYHA,这可能与各HA的腐殖化程度相关.

Based on the method recommended by the International Humic Substances Society(IHSS),humic acids(HAs)were extracted from the peatlands(NTHA),paddy fields(SDHA)and litter-covered soils(LYHA)in Qingyi town,Mianyang City,Sichuan Province.The structural characteristics of HAs were compared by element analysis,UV-vis spectra,FTIR spectra and 3D-EEM spectra.Meanwhile,the effects of HAs on the photodegradation of sulfadiazine were evaluated.The results showed that:the four elements(C,H,O and N)were the predominant components of the HAs extracted from the peatlands(NTHA),paddy fields(SDHA),litter-covered soils(LYHA)and commercial products HA(SPHA).The order of HA aromaticity was SPHA>NTHA>LYHA>SDHA.Compared with the extracted HAs,SPHA contained more nitrogenous compounds,aromatic compounds,lipid compounds and oxygen-containing functional groups,which could bring more photoactive groups because of high humification degree.Sulfadiazine(SDZ)showed the better stability under dark environmental conditions.However,the degradation efficiency of SDZ exposed to UV irradiation was low in pure aqueous solution,and the degradation process belongs to apparent first-order kinetic reaction.When the different HAs were added,the photodegradation ratio of SDZ in ach reaction system was greater than that in pure aqueous solution.And,the order of promotive effect with HAs was SPHA>SDHA>NTHA>LYHA,which was related to the humification degree of HAs.