环境因子对胡敏酸介导下SDZ光解行为的影响

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Fe³⁺）、离子强度（NaCl）以及金属离子（Ca²⁺、Mg²⁺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；Fe³⁺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（C_NaCl=50mmol/L）抑制作用较强.金属离子（K⁺、Ca²⁺和Mg²⁺）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⁺ > Ca²⁺ > Mg²⁺，单价阳离子对SDZ光降解影响较为明显.

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

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 Fe³⁺), ionic strength, and metal ions (Ca²⁺, Mg²⁺ 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 (2mg/L) and low HA concentration (15mg/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; Fe³⁺ 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 (C_NaCl=50mmol/L). The metal ions (K⁺, Ca²⁺, and Mg²⁺) 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⁺ > Ca²⁺ > Mg²⁺. The effect of monovalent cation on SDZ photodegradation was more significant.