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Zhou C.,Tongji University | Gao N.,Tongji University | Deng Y.,Montclair State University | Chu W.,Tongji University | And 2 more authors.
Journal of Hazardous Materials | Year: 2012

Disinfection by-products (DBPs) are a great challenge to our drinking water security. Particularly, nitrosamines (NAms), as emerging DBPs, are potently carcinogenic, mutagenic, and teratogenic, and have increasingly attained public attention. This study was to evaluate the performance of the NAms degradation by the ultraviolet (UV) irradiation (253.7nm) in the presence of hydrogen peroxide (H2O2). In the UV/H2O2 system, hydroxyl radicals (OH), a type of nonselective and powerful oxidant, was produced to attack the molecules of NAms. Factors affecting the treatment efficiency, including the H2O2 dosage, initial NAms concentration, UV irradiation intensity, initial solution pH, and inorganic anions present in water, were evaluated. All the NAms degradation exhibited a pseudo-first-order kinetics pattern. Within 60min, 0.1mg/L of any NAms could be almost decomposed except NDPhA that required 120min for complete removal, at 25μmol/L H2O2 and at initial pH 7. Results demonstrate that the UV/H2O2 treatment is a viable option to control NAms in water. © 2012 Elsevier B.V.


Gao Y.-Q.,Tongji University | Gao N.-Y.,Tongji University | Deng Y.,Montclair State University | Yin D.-Q.,Tongji University | And 3 more authors.
Desalination and Water Treatment | Year: 2015

Heat-activated persulfate to produce highly reactive sulfate radicals (Formula presented.) to oxidize sulfamethoxazole (SMX) in water was studied. The SMX degradation rate was significantly influenced by the reaction temperature, persulfate dose, initial pH, and co-existing anions. Higher temperature achieved higher degradation rate. The calculated activation energy for hot persulfate oxidation of SMX was approximately 130.93 kJ/mol. The degradation rate constant was proportional to the persulfate dose. An alkaline condition favored the SMX degradation. Effects of anions on the SMX degradation were species-dependent. Cl−, (Formula presented.) , and (Formula presented.) inhibited the SMX degradation, to different degrees. In contrast, (Formula presented.) accelerated the treatment. The SMX decomposition was associated with hydroxylation, sulfonamide bond breakage, and oxidation of the amine groups. Toxicity tests revealed production of more toxic products. Therefore, appropriate post-treatments need to be considered to address the undesirable byproducts. © 2014 Balaban Desalination Publications. All rights reserved.


Gao N.,Tongji University | Zhu S.,Tongji University | Ma Y.,Tongji University | Rong W.,Wuxi Water Supply General Company | And 2 more authors.
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | Year: 2013

The degradation of 2, 4, 6-trichlorophenol (2, 4, 6-TCP) by UV/H2O2 in aqueous solutions was investigated. The effects of H2O2 dosage, pH, cations, anions, tert-butanol and humic acid on the removal of 2, 4, 6-TCP were evaluated and the mechanism for oxidation of 2, 4, 6-TCP by UV/H2O2 was analyzed by using LC-HESI-MS-MS. The results indicate that the UV-H2O2 degradation of 2, 4, 6-TCP well follows pseudo first order kinetics. The removal of 2, 4, 6-TCP and reaction rate can be enhanced by increasing H2O2 dosage. When the dosage of H2O2 is 10 mmol/L, the reaction rate constant K reaches 0.1094 min-1. The pH value of the solution greatly influences the 2, 4, 6-TCP degradation and the degradation performs well in acid condition. Irons in water have a significant influence on the 2, 4, 6-TCP degradation by UV/H2O2. CO3 2- inhibits the 2, 4, 6-TCP degradation significantly, however, Fe3+ exhibits an obvious promoting effects on 2, 4, 6-TCP degradation. A majority of 2, 4, 6-TCP transforms into dichlorocatechol or dichlorohydroquinone without complete mineralization.


Wang H.,Tongji University | Gao N.-Y.,Tongji University | Ou H.-S.,Tongji University | Rong W.-L.,Wuxi Water Supply General Company | And 2 more authors.
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | Year: 2012

3-D excitation emission matrix fluorescence (EEM) spectroscopy was used for degradation studies of Microcystic Aeruginosa by O 3 and UV-C irradiation. Extracellular dissolved organic matter (EDOM) and intracellular dissolved organic matter (IDOM) of algal suspension were analyzed by EEM and quantified by fluorescence regional integration (FRI) methods. Protein-like matter was determined to be the major fluorescence component of EDOM, while amino acid-like and protein-like matter was found to constitute IDOM. The results show that the variation tendency of protein-like matter and humus-like matter are different as a result of specific disinfection and degradation mechanisms of O 3 and UV-C. Medium intensity UV-C irradiation is confirmed to be an efficient cyanobacterial inactivation method with high purifying effect of dissolved fluorescence organic matter, while low-dosage O 3 has limited effect on cyanobacterial-based matter removal.


Wang W.-Q.,Tongji University | Gao N.-Y.,Tongji University | Li L.,Tongji University | Zhang K.-J.,Tongji University | Rong W.-L.,Wuxi Water Supply General Company
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | Year: 2011

An artificial neural network (ANN) model of microcystin-LR (MC-LR) degradation by ozonation was studied. The affect on degradation of ozone dose, MC-LR initial mass concentration and pH was investigated. And the removal effect with various factors was simulated and predicted by the model. The results show that the degradation rate is invariable with different MC-LR initial mass concentrations. The addition of ozone dose can increase the MC-LR degradation rate effectively, the decline of pH can improve the degradation effect obviously, especially in acidity condition. A big removal efficiency can be gotten in a short time with acidity condition and large ozone dose. The ANN model can be used to predict the degradation effect of MC-LR with complex various factors, provide theoretical foundation for MC-LR degradation and overcome the limitation of common model.

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