| Tetracyclines play a positive role in livestock farms and human therapy. Due to thedepressed absorption of antibiotics by human and animals, unabsorbed antibiotics excretedfrom the body via urine or feces enter into the aqueous environment through migrationtransformation. For the biotoxics of antibiotics to the ecosystem, increasing attention has beenpaid to elucidate the degradation pathway of it and thereby developing some processes toeliminate it from the environment. However，the traditional technologies are inefficient toremove the antibiotics as it exhibites high stability in the wastewater, thereby we here adoptedphotocatalytic oxidation which has significant advantiges in the treatment of stable organiccompounds to degrade the antibiotics.In this thesis, the reaction of degradation of oxytetracycline were investigated underhydrolysis，photolysis and photocatalytic degradation by using plastic optical fber whichtransmiting xenon light as light source. Oxytetracycline samples were analyzed by liquidchromatography-mass spectrometry (LC-MS). Results indicated that: Oxytetracyclinedecreased constantly from0to7day with the increasing temperature from10±1to35±1℃.Oxytetracycline also decreased with the increasing pH from3.0to10.5. The effects ofphotocatalytic are greater than that of hydrolysis or photolysis. Effects of catalyst dosage onthe reaction were relatively considerable with the increase of nano-TiO2dosage andconversion rate. With the increase of intial concentration of oxytetracycline, the conversionrate increased first and then decreased, and finally increased again. Amongst the concentrationrange in this research, photocatalytic reaction was promoted with Ca2+in high concentration(Ca2+≥0.1mmol/L) while inhibited in high concentration (Ca2+≤0.1mmol/L). According tothe analysis of LC-MS, five kinds of main products of photocatalytic degradation weredetected. Moreover, on the basis of these results five probable degradation pathways werespeculated. |
PDF Full Text Request