Degradation Of Some Typical Environmental Hormone And PPCPs By Thermal-activated Persulfate

The safety of the water environment is the problem which people concerning increasingly. In recent years, with the development of industry and the need of human life, a large amount of organic pollutants have being emission to water environment consciously or unconsciously. The range of organic pollutants are widely and the harm to the environment are varies. In recent ten years, people paid great attention on environmental hormones and PPCPs. The chemical and pharmaceutical wastewater, sewage and agricultural wastewater are the main courses of these pollutants. Due to the improvement of living standards and the development of livestock breeding, these materials have been extensively and widely used, which have been detected frequently in surface water. These compounds with persistence, biological activity and bio-accumulation are difficult to degrade in environment. They can interfere the growing and metabolism of organisms and cause toxic effect to the biological with long-term exist in the environment. They can get into human or animals bodies through the food chain, causing endocrine disorders and persistent harm to human health and environmental. The risk of emerging organic pollutants has attracted more and more concern.Conventional sewage treatment process is designed to remove nutrients and oxygen organics, lacking of technologies to remove environmental hormone and PPCPs specifically, that these pollutants can't be degraded effectively. The advanced oxidation technology based on sulfate radical is just rise in recently years. Sulfate radical have strong oxidizing property which can oxidize and degrade these pollutants efficiency and without introducing new contaminants into water. It has great development potential and benign apply prospects in water treatment.In this study, exploiting the outstanding oxidative capacity of thermal-activated persulfate, we explored the efficacy of bisphenol A, nonylphenol and triclosan removal by S2O82-. Reaction conditions on this reaction, such as temperature, initial concentration of persulfate solution. pH value, anions (Cl-,NO3-, SO42-) and humic acid concentration, were tested. The intermediate were detected by GC-MS and we also inferred the oxidative degradation pathway of these pollutants. The degrade performance of thermal-activated NaS2O8 on gemfibrozil is investigated as well, the main results are as follows:(1) Thermal-activated persulfate could degrade some refractory organic pollutants effectively, the degradation processes conformed to the pseudo first-order reaction kinetics. In the condition of 50?, the degradation efficiency of BPA reached 68.5% after 60min, the degradation rate of nonylphenol reached 64.8% as well, the degradation rate are both more than 50%.(2) The degradation efficiency by persulfate increased with increasing of the activation temperature. The degradation rate of BPA and nonylphenol increased significantly with the increase of temperature. The degradation rate of BPA and nonylphenol under 50? was 68.5% and 64.8%, respectively. BPA completely degraded in 20min and nonylphenol also completed degraded in 40min when the temperature rose to 70?. The degradation efficiency of triclosan and gemfibrozil also increased with increasing temperature, but the growth rate is smaller. When the temperature rose from 50 ? to 70 ?, the degradation rate of triclosan increased from 21.4% to 27.8%, while the degradation rate of gemfibrozil just increased from 8.7% to 11.5% when the activation temperature rose from 25 ? to 45 ?.(3) The degradation rate increased with the increase of initial persulfate concentration. Under the experimental condition, when the persulfate initial concentration increased from 2.5 mM to 10 mM, the degradation rate of BPA increased from 52% to 73.2%; when the initial concentration increased from 250 mg/L to 1000 mg/L, the degradation rate of nonylphenol increased from 56.6% to 61.9%. In the treat of triclosan and gemfibrozil, the degradation rate elevated slightly with the increase of the concentration of persulfate.(4) The degradation rate of organic pollutants is imparity in different pH. In the study, acidic reaction solution, instead of neutral and alkaline reaction solution, can accelerate the reaction of BPA, it followed the order pH5.0> pH9.0> pH7.0. The degradation rate reduced with the increase of pH in the treatment of triclosan, nonylphenol and gemfibrozil.(5) Coexisting anions displayed suppressive effects on the degradation of organic pollutants. To different organic pollutants, the inhibitory effect is also different. The inhibitive capacity with anions of BPA. triclosan, nonylphenol and gemfibrozil followed the order SO42-> Cl-> NO3-, Cl-> SO42-> NO3-> HCO3-, NO3->HCO3->SO42->Cl-and Cl->SO42->NO3->HCO3-,respectively.(6) The natural organic matter could suppress the degradation of organic pollutants. Humic acid showed negligible inhibition on the removal of BPA, triclosan, nonylphenol and gemfibrozil, the inhibition increased with increasing concentration of HA.(7) The degradation intermediates were detected by GC-MS. A total of 4 compound, hydroquinone, p-isopropenyl phenol,2-Methyl-2,3-dihydrobenzofuran and 3-Methyl-2. 3-dihydrobenzofuran were identified as products or intermediates in the study of BPA. It could be inferred that, the carbon atom attached to electron-rich benzene ring and isopropyl was fractured first, then formed these intermediates through hydroxylation. addition or connection with short chain alkanes, the intermediate product were further oxidative decomposition by SO4-·and·OH, eventually mineralized to CO2 and H2O. The major intermediates of nonylphenol were octylphenol, amylphenol and isobutyl phenol, respectively. It could be inferred that the alkyl chain on the benzene ring first fractured. In the reaction of triclosan, no related intermediate is detected.