环境因子对胡敏酸介导下SDZ光解行为的影响

Environmental factors of influencing the photodegradation of sulfadiazine by humic acid mediated system

研究了在纯水条件及两种不同来源胡敏酸(HA)介导下,磺胺嘧啶(SDZ)和水稻土胡敏酸(SDHA)、泥炭土胡敏酸(NTHA)的不同浓度、pH值、光敏离子(NO3^-和Fe^3+)、离子强度(NaCl)以及金属离子(Ca^2+、Mg^2+和K^+)等环境因子对SDZ紫外光降解的影响.结果表明:光照下,pH=7.1对两种体系的SDZ光降解有促进作用且效果最好.低SDZ浓度(2mg/L)以及低HA浓度(15mg/L)条件下使SDZ光解速率较快.光敏离子中NO3^-通过光生·OH,促进了纯水中SDZ的光解,但在HA体系中,HA具有猝灭·OH的效应造成SDZ的光解速率低于纯水;Fe^3+在HA体系下均表现为抑制作用,且抑制强度为NTHA>SDHA.在纯水中SDZ的光解速率随NaCl浓度增加而增加,HA介导下,较低浓度NaCl(CNaCl=50mmol/L)抑制作用较强.金属离子(K^+、Ca^2+和Mg^2+)在纯水中对SDZ的光解影响程度较弱,但在HA体系中均表现为抑制作用,抑制强度为K^+>Ca^2+>Mg^2+,单价阳离子对SDZ光降解影响较为明显.

This experiment studied the influence of some environmental factors,including various concentration of sulfadiazine(SDZ),paddy soil humic acid(SDHA),and peat soil humic acid(NTHA),different pH values,photosensitive ions(NO3 and Fe^3+),ionic strength,and metal ions(Ca^2+,Mg^2+and K^+)on the photodegradation of SDZ in pure water and two separate sources of HA solution.The results showed that under the condition of pH=7.1,the photodegradation of SDZ has been promoted in both systems and had the best effect.The photolysis rate of SDZ was speeded up under the condition of low SDZ(2 mg/L)and low HA concentration(15 mg/L).Photosensitive ions NO3^-promoted the photolysis of SDZ in pure water by light producing-OH,but in HA systems,HA could inhibit OH and cause the photolysis rate of SDZ to be lower than that in pure water;Fe^3+exhibited inhibition in HA systems,and the intensity was NTHA>SDHA.The photolysis rate of SDZ in pure water increased when the concentrations of NaCl became higher,under HA systems,the inhibition effect was stronger under the lower concentration of NaCl(CNaCl=50 mmol/L).The metal ions(K^+,Ca^2+,and Mg^2+)in pure water had a weak inhibition effect on the photolysis of SDZ,but K+clearly showed inhibition in HA systems.The inhibition intensity was K^+>Ca^2+>Mg^2+.The effect of monovalent cation on SDZ photodegradation was more significant.