Sonochemical Degradation Of Triclocarban And Chloramphenicol In Aqueous Solution

Pharmaceutical and personal care products (PPCPs) are a kind of emergingcontaminants due to its environmental hazards, which have aroused widespreadattention at home and abroad. Therefore, it is crucial to investigate novel and effectivetreatment technologies for the degradation of PPCPs. To reduce the interference in thestudy of the mechanisms chloramphenicol (CAP) and triclocarban (TCC) are selectedas the target contaiminates of PPCPs. The aim of the work is to seek efficientdegradation method and to investigate the mechanism of degradation of two types ofwastewater. It is expected to provide basic data theoretical guidance and applicationreference for the two real wastewater treatment.This research includes the followingaspects:1. Investigations on CAP degradation. Co2+catalyzed sodium peroxydisulfatecombined ultrasound (SPDS/Co2+/US) and Fenton-like combined ultrasound(US/Fenton-like) were used to degrade CAP wastewater. Meanwhile, degradationtrends and influencing factors of CAP was investaged in this process. The optimumreaction conditions were determined via single factor test and orthogonal test.Furthermore, the degradtion of CAP and TOC were analyzed in order to study thereaction mechanism. Finally, the degradation mechanisms were investigated viaantimicrobial, TOC, GC-MS and LC-MS, and the degradation pathway of CAPwas further proposed. The main results were as follows:(1)Degradation of CAP under SPDS/Co2+/US system. The degradation rateachieved at68.5%in8hours without adjusting the pH. CAP degradation rate increasedwith decreasing pH and concentration of cobalt chloride (＜0.1mmol/L).97%treatment efficiency of CAP was achieved under the optimum at conditions of pH2.0,power400W, the initial concentration of SPDS5.0mmol/L, and cobalt chloride0.1mmol/L. It was found that the antimicrobial resistance of CAP decreased significantlyafter treatment. However, the efficiency of mineralization was not promising. Apotential degradation pathway was proposed on the basis of the five degraded products of CAP.(2)Degradation of CAP under US/Fenton-like system. Under acid condition, theCAP degradation achieved at95%in US/Fenton-like process. Strong acid environment(pH=2.0or3.0), showed high70points degradation efficiency of CAP than that ofneutral, weak acid and base environment. Furthermore, there were optimum dosage ofH2O2and sponge iron in this process which value were4.00mmol and1.0g/L,respectively. By the application and analysis of RSM, the theoretical value of CAPdegradation was100.64%in this syetem at the initial pH2.32, the dosage of Fe1.0g/L,the initial contentration of H2O23.54mmol/L. Compared with the actual value, therelative error is3.07%which confirm the reliability of the optimization model. It wasfound that antimicrobial resistance of CAP decreased significantly while themineralization rate was lower than12%. May generate five kinds of intermediatedegradation products, the possible reaction pathways were deduced by means of thefive degraded products.2. Investigations on TCC degradation. It was found that US/Fenton-like systemshowed high degradation efficiency on the degradation of CAP. To expand theapplication of US/Fenton-like system, it was further employed to degrade TCC.. Theresearch was mainly focused on the effects of pH and H2O2concentration on thedegradation rate of the TCC. The results showed that the removal efficiency of TCCincreased with the increasing of H2O2concentration ([H2O2]≤2.0mmol/L) underacidic conditions (pH≤3.0) in US/Fenton-like process. It is expected to investigatetheTCC degradation mechanismin the future research.