水中四环素类化合物在不同光源下的光降解

研究了模拟太阳光和实际室外太阳光下四环素类化合物在水溶液中的光降解。结果表明,四环素类化合物(TCs)在模拟太阳光照射下均能发生直接光降解,且其降解速率随pH不同变化很大。四环素(TC)、土霉素(OTC)、金霉素(CTC)和多西环素(DTC)的光降解速率随溶液pH升高明显加快,而米诺环素(MTC)在水中的光降解速率随溶液pH升高略有下降。天然水体pH范围内,模拟太阳光照下四环素类化合物表观光降解速率常数在0.004～0.026 min-1范围内,降解半衰期在26～136 min范围内。在室外实际太阳光照下,四环素类化合物光降解反应速率与太阳光强成正比例关系。晴朗无云天气下,四环素类化合物降解半衰期在春冬季节较长、夏季节较短;四环素在东江实际水体中表观光降解速率很快,在冬季晴天天气下,其平均半衰期仅为8.2 min。

Photodegradation of tetracyclines compound in aqueous solution under different light irradiation

The aquatic photochemical behaviors of tetracyclines(TCs) were investigated under the simulated and natural sunlight.The results indicated that TCs were directly degraded under the simulated sunlight.Moreover,the TCs’ photodegradation efficiency changed as the solution pH.The photodegradation of tetra cycline(TC),oxytetracycline(OTC),chlortetracycline(CTC),and doxycycline(DTC) increased with the increase of pH,whereas the minocycline(MTC) photodegradation exhibited different trend.In the pH range of natural water,the reaction rate constants of TCs ranged from 0.004～0.026 min-1,and the half-lives of photodegradation of TCs ranged from 26～136 min under simulated sunlight.The direct photodegradation rate of TCs is proportional to the sunlight intensity.Photolysis of TCs under sunlight irradiation at different season showed that the degradation is faster in summer compared with that in spring/winter.The photodegradation of tetracycline in Dongjiang River showed a fast rate.The average half-lives of TC was 8.2 min in clear weather of winter.