超声波降解四环素类抗生素废水

采用超声波降解模拟废水中四环素类抗生素(TCs):土霉素(OTC)、四环素(TC)和金霉素(CTC),考查废水初始浓度、初始pH、超声波输入功率密度、曝气量和自由基清除剂(正丁醇)对降解效率的影响。结果表明,超声波可以快速高效地降解废水中的TCs,CTC最易被降解,TC和OTC次之;在OTC、TC和CTC初始浓度0.25 mg/L,初始pH=8.2,声功率密度1.2 W/mL,气水体积比30∶1的条件下,超声波辐照20 min后去除率分别达到76.8%、84.0%和94.4%。在实验研究条件下,TCs去除率均随初始浓度(0.25~2.00 mg/L)的增大而降低,但总去除浓度升高;碱性条件有利于TCs降解,去除率随初始pH(6~11)升高而升高;功率密度(0.24~1.96 W/mL)越高,TCs去除率也越高;曝气后TCs的去除率明显升高,随着气水比(10∶1~60∶1)的增大,去除率逐渐上升;正丁醇有效抑制TCs超声波降解,可推断TCs主要降解途径为自由基氧化。TCs超声波降解过程符合伪一级动力学反应特征。

Ultrasonic degradation of tetracyclines in aqueous solution

This study investigated the tetracyclines(oxytetracycline,OTC; tetracycline,TC; chlortetracycline,CTC) degradation upon ultrasonic action under different experimental conditions.The effects of initial concentration (0.25~2.00 mg/L),initial pH(6~11) of the solution,power density (0.24~1.96 W/mL),aeration volume and hydroxyl radical scavenger (normal butanol) were evaluated.It was found that tetracyclines could be degraded rapidly by ultrasonic irradiation,the removal rates were CTC >TC >OTC and CTC was more easily degraded than TC and OTC.When the concentration was 0.25 mg/L,pH was 8.2,power density was 1.2 W/mL and aeration volume was 30:1air/water,(V/V)],the removal efficiencies of OTC,TC and CTC were 76.8% 84.0% and 94.4% after 20 min irradiation,respectively.All the impact factors mentioned above had remarked effects on tetracyclines removal efficiencies,which increased with increasing initial pH,power density and aeration volume,but decreased with increasing concentrations of teracyclines and volumes of normal butanol added.Pseudo-first order reaction model can be used for the fitness of TCs degradation by ultrasonic action.