磺胺二甲基嘧啶在过硫酸盐存在下的辐照降解研究

Radiolysis of sulfadiazine from wastewater in the presence of persulfate

本研究对磺胺二甲基嘧啶(SMT)在不同条件下的辐照降解进行了研究.SMT(20 mg·L^(-1),约0.072 mmol·L^(-1))在外加过硫酸根浓度为0、1、2、4、10和20 mmol·L^(-1)条件下分别进行辐照,发现伽马辐照可有效去除水中的SMT,并可极大地促进溶液TOC的去除,过硫酸盐与伽马辐照联合作用表现出明显的协同效应.在本研究中,各条件下的辐照降解反应均符合准一级反应动力学.在外加过硫酸盐的条件下,溶液的矿化度可以得到极大的提高,当吸收剂量为1 k Gy时,其矿化度由3.5%提高到22.8%,当吸收剂量为5 k Gy时,矿化度由14.1%提高到70.1%.在辐解后的溶液中,利用IC检测到硫酸根离子(SO_4^(2-))、甲酸根离子(HCOO^-)和乙酸根离子(CH_3COO^-)3种离子的存在,一部分中间产物通过GC-MS检测得到,常见的含氮离子(NO_2^-、NO_3^-和NH_4^++)并未在溶液中检测到.同时,本研究还深入探讨了SMT辐照降解机理和降解途径.

Radiolysis of sulfamethazine（ SMT） was characterized under different conditions in this research. SMT solutions（ 20 mg·L^-1） were irradiated in the presence of 0,1,2,4,10 and 20 mmol·L^-1S2O8^2-,respectively. The results show that gamma radiation was effective in both SMT degradation and TOC removal,and the synergistic effects of gamma radiation with persulfate（ S2O8^2-） were obviously. The degradation reactions conformed to the pseudofirst-order reaction kinetics. With absorbed doses of 1 k Gy to 5 k Gy,TOC removal rates were dramatically elevated after S2O8^2- was added-3. 5% to22.8% and 14.1% to 70.1%,respectively. In the process,three ions（ SO4^2-,HCOO^-and CH3COO^-） were detected to be released from the radiolytic solutions by ion chromatography（ IC）. Furthermore,complicated products were identified by GC-MS. The normal N-containing ions（ NO2^-,NO3^-and NH4^＋） were not detected in the process. The pathways and mechanisms for the radiolytic process in the aqueous solution were proposed.