通过分析污泥中3种典型抗生素环丙沙星(CIP)、土霉素(OTC)和磺胺二甲嘧啶(SM2)的热解过程与失重特性,研究其热解动力学特征。结果表明:CIP、OTC、SM2主要热解温度区间分别为150-625℃、220-600℃、260-480℃;初始热解温度以及最大失重峰对应温度均为OTC〈SM2〈CIP;C1P热解具有2个失重峰,OTC与SM2热解仅有1个失重峰;且SM2热解失重峰最高,反应最剧烈;抗生素热解最终残留物均为残碳,且CIP热解残留率最低,为18.9%。抗生素热解过程可分为3阶段:第1阶段反应级数均为2级,活化能最高,频率因子最大;OTC、SM2与CIP热解平均活化能分别为50.19、72.31、81.85kJ·mol^-1,说明OTC热解反应最容易进行,CIP热解则相对较难。上述结果将为污泥热解炭化工艺实现抗生素消减提供良好的理论基础。
The thermal degradation process and mechanism of three representative antibiotics,ciprofloxacin,oxytetracycline and sulfamethazine were studied with the help of thermogravimetric analysis method. The pyrolysis kinetics characteristics were analyzed by thermogravimetry. Results showed that the main pyrolysis temperature ranges of CIP,OTC and SM2 were from 150 to 625 ℃,220 to 600 ℃ and 260 to 480 ℃. Their initial decomposition and weightlessness peak temperature were in the same order:OTC〈 SM2 〈CIP. Two weightlessness peaks appeared during the CIP pyrolysis process,but forOTC and SM2,only one peak were found. The highest and sharpest peak of SM2 indicated the intense pyrolysis reaction. The poyrlysis residue of antibiotic was residual-carbon and the rate of ciprofloxacin residues was minimum,about 18. 9%. For all of the three antibiotics,the dominating pyrolysis process included three steps and the first step reaction order were 2,where the highest activation energy and frequency factor occurred. Furthermore,the average activation energy of three steps for oxytetracycline,sulfamethazine,ciprofloxacin from small to large followed by 50. 19,72. 31,81. 85 kJ·mol^-1,which suggested thatOTC was the easiest to be pyrolyzed. Those conclusions mentioned above provide a theory basis for eliminating antibiotics completely in sludge by the process of pyrolysis and carbonization.