Journal of Environmental Chemical Engineering
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2023
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IF 7.7
Xianni Song,Junhua Zhang
Polyvinyl alcohol (PVA) is a kind of refractory organic polymer with high COD and low BOD. Efficient treatment of PVA wastewater has always been a challenging subject especially for ultra-high concentration (UHC). In this paper, based on our previous work, a sequential combination process method including NaClO chain breakage followed by Cu x O activated carbon catalytic oxidation was developed to efficient treat UHC PVA wastewater. The sequential combination system was optimized by monitoring the treatment performance with different key parameters (such as oxidant dosage, Cu loading and catalyst dosage, two-stage reaction time, pH value, etc.). And the COD of PVA wastewater declined from the initial 206,240.00 mg/L to 557.78 mg/L (removal rate 99.73 %), the PVA concentration decreased from the initial 171,325.00 mg/L to 19.94 mg/L (removal rate 99.99 %) under the optimal conditions. Through the discussion of the combined processes, it was found that both chain breakage and catalytic oxidation were necessary and indispensable to achieve efficient degradation of PVA wastewater. Additionally, the free radical scavenging experiments show that the combined oxidation process was mainly controlled by the catalytic oxidation process, and followed the free radical reaction mechanism with·OH as the main oxidant. Based on this, it is recommended that subsequent researchers focus on the combined process for the treat of refractory organic wastewater.
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高影响因子
CELLULOSE
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2021
·Vol. 28
·期 18
·11315-11328
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IF 5.044
Wang Huimin,Wang Xiaoying,Sun Tingting,Li Peixin,Chu Xiaomeng,Xing Xuteng,Liu Shaojie,Tang Erjun
As a highly efficient nitroxide radical catalyst for selective catalytic oxidation of cellulose, N-hydroxyphthalimide (NHPI) has attracted much attention because of its low price and light cellulose degradation. However, NHPI is insoluble in water and is difficult to recycle because of its small molar mass. To address the above issues, the water-soluble polyethylene glycol (PEG)-immobilized NHPI catalyst (PEG-NHPI) was designed and prepared in this work. Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), size exclusion chromatography (SEC) and UV–Vis light spectrophotometry were used to characterize PEG-NHPI. The results showed that PEG-NHPI catalysts with good water solubility and adjustable NHPI loading amounts were successfully synthesized. Using NaBr as promoter and NaClO as oxidant, PEG-NHPI mediated oxidation of cellulose was carried out and good catalytic performance was found. The catalytic performance of PEG-NHPI mediated oxidation of cellulose in water was higher than that in acetonitrile–water. The carboxyl content of PEG-NHPI oxidized cellulose could reach the level of free NHPI oxidized cellulose, and was equivalent to 68% of 2, 2, 6, 6-tetramethylpiperidine-N-oxyl (TEMPO) oxidized cellulose, while the degradation degree of cellulose was greatly reduced by more than 40%. The catalytic performance did not decrease significantly after six oxidation cycles. The structure of recycled PEG-NHPI was not changed. These results indicated that immobilizing NHPI onto PEG can achieve the unification of high catalytic performance and good recyclability.
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JOURNAL OF MEMBRANE SCIENCE
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2019
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IF 7.015
Jiaqi Ding,Songlin Wang,Pengchao Xie,Yujia Zou,Ying Wan,Yongsheng Chen,Mark R. Wiesner
This paper presents an investigation of the variation in membrane characteristics and formation of halogenated by-products during the off-line chemical cleaning of algae-fouled ultrafiltration (UF) membrane by NaClO solution. The chemical treatment led to the recovery of membrane flux, decrease of membrane hydrophilicity and HA rejection. Proteins, amino acids, and polysaccharides contained in algal cells were easy to adsorb on the membrane surface and contributed to the formation of halogenated by-products during the NaClO cleaning process. The increase of NaClO concentration and temperature significantly promoted the formation of most selected halogenated by-products. With the increase of pH, trichloromethane (TCM), dichloroacetic acid (DCAA) and trichloronitromethane (TCNM) rose continuously; monochloroacetic acid (MCAA), trichloroacetic acid (TCAA) and trichloroacetonitrile (TCAN) followed an increasing and then decreasing trend. With the prolonged exposure time from 2 to 24 h, most halogenated by-products from the cleaning of algal cell-, extracellular organic matter (EOM)- and humic acid (HA)-fouled membranes monotonically increased, while the formation of 1,1-dichloro-2-propanone (DCP) and dichloroacetonitrile (DCAN) varied differently. NaClO cleaning of algal cell-fouled membrane generated much lower concentrations of selected carbonaceous halogenated by-products and TCNM, but caused higher yields of haloacetonitriles (HANs) than that of HA-fouled membrane.
研究领域:
环境科学
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水处理工程
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高影响因子
CHEMICAL ENGINEERING JOURNAL
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2022
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IF 16.744
Rong Huang,Tong Zhang,Qiaoying Wang,Hongbo Gu,Zhen Zhou,Zhichao Wu,Zhiwei Wang
Membrane fouling can be effectively alleviated by using conductive membrane and external electric field in membrane bioreactor. However, the transformation and removal mechanism of foulants during the electrochemical process needs to be further explored. The present work investigated the degradation mechanisms and cleaning efficiency of organic foulants by electric field and sodium hypochlorite (NaClO) on the composite conductive microfiltration membranes. The results show that the electrochemical oxidation obtained a great degradation efficiency of bovine serum albumin (BSA) at current densities of 40 and 80 A/m 2 , which was equivalent to that of high-dose NaClO (160 mg/L). However, the degradation efficiency of sodium alginate (SA) was much lower than that of BSA under the same cleaning strategy, due to its strong antioxidant activity. It was also found that NaClO oxidation can decompose BSA macromolecules into small molecules instead of mineralization, while electrochemical oxidation can convert dissolved BSA into foams and flocs by electrocoagulation, thus reducing the BSA concentration in the solution. During the electrochemical cleaning, indirect electrochemical oxidation through the formation of strong oxidants played an important role in the degradation of BSA and SA, and the role of OH· was more significant than that of O 2 · - . The combination of electric fields and NaClO showed great membrane cleaning efficiency. Moreover, the combination of electrochemical cleaning could not only prevent a large number of precursors from being converted to halogenated by-products, but also shorten the chlorination time and reduce the chlorine concentration, which can alleviate the secondary pollution of cleaning solution.
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JOURNAL OF HAZARDOUS MATERIALS
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2024
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IF 12.2
Qian Guo,Zuxin Xu,Wenhai Chu,Jingyi Zhang,Haiyue Qi,Chun Lu,Xingyu Wang
During wet weather, sewer overflow pollution can pose a serious threat to surface water. In order to reduce the impact of overflow discharge on receiving waters, ferric chloride (Fe(Ⅲ))/potassium ferrate (Fe(Ⅵ))/polyacrylamide (PAM) coagulation (Fe(Ⅲ)/Fe(Ⅵ)/PAM) combined with sodium hypochlorite (NaClO) oxidation was proposed. Different combinations were constructed, including pre-oxidation coagulation (NaClO-Fe(Ⅲ)/Fe(Ⅵ)/PAM), pre-coagulation oxidation (Fe(Ⅲ)/Fe(Ⅵ)/PAM-NaClO), and synchronous coagulation oxidation (NaClO+Fe(Ⅲ)/Fe(Ⅵ)/PAM). The combined processes achieved efficient removal of conventional contaminants, and the produced byproducts were controlled, especially in the NaClO-Fe(Ⅲ)/Fe(Ⅵ)/PAM. The obvious discrepancy in the sulfamethoxazole (SMX) removal was observed in different processes. NaClO affected the distribution of hydrolyzed iron species, and the proportion of active iron in the NaClO-Fe(Ⅲ)/Fe(Ⅵ)/PAM significantly increased. More complexation sites were generated in the NaClO-Fe(Ⅲ)/Fe(Ⅵ)/PAM, which can complex with the coagulant and then effectively transfer to the flocs. The composition of the flocs further confirmed the differences in coagulation characteristics. The generated·OH played a crucial role in SMX removal in the NaClO+Fe(Ⅲ)/Fe(Ⅵ)/PAM, and ClO·was responsible for partial removal of ammonia nitrogen (NH 4 + -N). The contribution of high-valent iron species was confirmed, and the introduction of NaClO promoted the generation of iron species. This study may provide an ideal for overflow treatment to improve the urban water environment.
研究领域:
环境工程
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水处理
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化学工程
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PubMed
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2022
·
IF 4.326
Junqi Cheng,Zhitao Han,Jiawei Li,Xinxiang Pan
Previous work proposed a one-stage wet scrubbing in situ combined with O3 oxidation for simultaneous removal of NO and SO2 from flue gas, and the results showed that wet scrubbing combined in situ with O3 injection could effectively improve O3 oxidant utilization efficiency. In this work, a follow-up research work was carried out to further explore the synergistic effect of dual oxidants of NaClO in the liquid phase and O3 in gas phase. The synergistic effects of O3/NO molar ratio and NaClO concentration in the circulating scrubbing solution on NOx removal performance was investigated systematically. The results showed that when molar ratio of O3/NO was 0.5 and NaClO concentration was 25 mM, NO could be oxidized completely and averaged NOx removal efficiency exceeded 70%. NOx concentrations in outlet gas and anion compositions in the scrubbed solution were analyzed, and the possible reaction paths of wet scrubbing NaClO solution in situ with O3 injection in denitration process were also discussed. When the solution pH was around 6, a relative balance between NOx oxidation and absorption might be achieved, resulting in a high NOx removal efficiency. The temperature of inlet flue gas imposed little impact on NOx removal efficiency due to the quick and efficient cooling effect by wet scrubbing. The increase of initial SO2 concentration led to a slight increase of NOx removal efficiency from 70 to 73.5%. A complete removal of SO2 could be achieved, but coexisting SO2 in flue gas would consume NaClO oxidant and shorten the reaction duration.
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JOURNAL OF ENVIRONMENTAL MANAGEMENT
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2026
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IF 9.2
Wei Xiang,Chen Wang,Chuan Yi,Yulun Wu,Na Xia,Xiangpu Zhang,Chunyan Xu,Mingjie Huang
Emerging contaminants (ECs) in drinking water sources pose significant risks to both human health and ecological security. However, their occurrence patterns and removal efficiencies in conventional drinking water treatment processes remain insufficiently studied, limiting the development of effective mitigation strategies. This study conducted a systematic investigation of major ECs in the Yangtze River and its largest tributary, the Han River. Among the analyzed ECs, pesticides and pharmaceuticals were identified as the predominant contaminants, with the Han River exhibiting particularly elevated concentrations. Monitoring across the treatment trains of two drinking water treatment plants (DWTPs) revealed that most ECs were removed with efficiencies below 50%, demonstrating the superior performance of chemical oxidation over physical methods. Lab-scale experiments further verified that UV irradiation and NaClO oxidation were the most effective treatment techniques, though both exhibited notable compound-specific selectivity. Structure-activity relationship analysis of 18 ECs indicated that direct photolysis by UV and direct oxidation by NaClO served as the primary removal mechanisms, with UV proving significantly more efficient. Removal selectivity was closely associated with molecular structural features: UV photolysis efficiency correlated with triplet excitation energy and the energy gap between the lowest unoccupied and highest occupied molecular orbitals (LUMO-HOMO), whereas NaClO oxidation efficiency was linked to excited-state energy and HOMO energy levels. These findings offer valuable insights for assessing source water risks and optimizing treatment strategies to enhance drinking water safety.
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PubMed
高影响因子
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