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Fenton process for degradation of selected chlorinated aliphatic hydrocarbons exemplified by trichloroethylene

QIANG Zhimin, BEN Weiwei, HUANG Chin-Pao

《环境科学与工程前沿（英文）》 2008年 第2卷 第4期   页码 397-409 doi: 10.1007/s11783-008-0074-0

摘要： The degradation of selected chlorinated aliphatic hydrocarbons (CAHs) exemplified by trichloroethylene (TCE), 1,1-dichloroethylene (DCE), and chloroform (CF) was investigated with Fenton oxidation process. The results indicate that the degradation rate was primarily affected by the chemical structures of organic contaminants. Hydroxyl radicals (OH) preferred to attack the organic contaminants with an electron-rich structure such as chlorinated alkenes (i.e., TCE and DCE). The dosing mode of Fenton’s reagent, particularly of Fe, significantly affected the degradation efficiency of studied organic compound. A new “time-squared” kinetic model, = exp(-), was developed to express the degradation kinetics of selected CAHs. This model was applicable to TCE and DCE, but inapplicable to CF due to their varied reaction rate constants towards OH. Chloride release was monitored to examine the degree of dechlorination during the oxidation of selected CAHs. TCE was more easily dechlorinated than DCE and CF. Dichloroacetic acid (DCAA) was identified as the major reaction intermediate in the oxidation of TCE, which could be completely removed as the reaction proceeded. No reaction intermediates or byproducts were identified in the oxidation of DCE and CF. Based on the identified intermediate, the reaction mechanism of TCE with Fenton’s reagent was proposed.

关键词： identified     1     1-dichloroethylene     kinetic     Dichloroacetic     Chloride    

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The effect of altering crosslinker chemistry during interfacial polymerization on the performance of nanofiltration membranes for desalination, organic, and micropollutants removal

《化学科学与工程前沿（英文）》 2023年 第17卷 第12期   页码 2025-2036 doi: 10.1007/s11705-023-2356-2

摘要： Chemistry of the polyamide active layer of a desalination membrane is critical in determining both its physical and chemical properties. In this study, we designed and fabricated three novel membranes with different active layers using the crosslinkers: terephthaloyl chloride, isophthaloyl chloride, and trimesoyl chloride. The crosslinkers were reacted with an aqueous solution of an aliphatic tetra-amine. Because these crosslinkers differ in their structures and crosslinking mechanisms during interfacial polymerization, the resultant membranes also possess different structural properties. The water contact angle of the fabricated membranes also varies; the water contact angles of 4A-3P-TPC@PSF/PET, 4A-3P-TMC@PSF/PET, and 4A-3P-IPC@PSF/PET, are 68.9°, 65.6°, and 53.9°, respectively. Similarly, the desalination performance of resultant membranes also showed variations, with 4A-3P-TPC@PSF/PET, 4A-3P-IPC@PSF/PET, and 4A-3P-TMC@PSF/PET having a permeate flux of 17.14, 25.70, and 30.90 L·m−2·h−1, respectively, at 2.5 MPa. The 4A-3P-TPC@PSF/PET membrane exhibited extensive crosslinking with aliphatic linear amine, and cationic dye rhodamine B, MgCl2, and amitriptyline rejection rates of 98.6%, 92.7% and 80.9%, respectively. The 4A-3P-TMC@PSF/PET membrane showed mediocre performance, while 4A-3P-IPC@PSF/PET membrane showed even lower performance, with a 35% rejection of methyl orange dye.

关键词： acid chlorides     covalent crosslinking     desalination     linear aliphatic amine     micropollutant removal     thin film composite membranes    

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Asymmetric transfer hydrogenation of prochiral ketone catalyzed over Fe-CS/SBA-15 catalyst

XUE Ping, WU Tao

《化学科学与工程前沿（英文）》 2007年 第1卷 第3期   页码 251-255 doi: 10.1007/s11705-007-0045-1

摘要： A heterogeneous chiral catalyst Fe(III)-CS (chitosan) complex/mesoporous molecular sieve SBA-15 (Santa Barbara Amorphous) was prepared. The asymmetric transfer hydrogenations of prochiral acetophenone and 4-methyl-2-pentanone to corresponding chiral alcohols were carried out on Fe-CS/SBA-15 at atmosphere pressure using 2-propanol as hydrogen donor. Effects of Fe content in catalyst, reaction temperature, reaction time and promoter KOH concentration on the conversion of substrates and enantioselectivity were investigated. Fe-CS/SBA-15 with 2.2% mass fraction Fe exhibits considerable enantioselectivity and catalytic activity for the asymmetric transfer hydrogenations of aromatic ketone and aliphatic ketone. Under optimal reaction conditions: KOH concentration 0.03 mol/L, reaction temperature 70ºC and reaction time 4 h, enantiomer excess (ee) of ()-1-phenylethanol and conversion of acetophenone can reach 87.4% and 27.7%, respectively. Under the above KOH concentration and reaction temperature and reaction time of 8 h, the ee of ()-4-methyl-2-pentanol and conversion 4-methyl-2-pentanone amounted to 50.2% and 25.5%, respectively.

关键词： asymmetric transfer     enantioselectivity     Fe-CS/SBA-15     aliphatic     aromatic    

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标题 作者 时间 类型 操作

Fenton process for degradation of selected chlorinated aliphatic hydrocarbons exemplified by trichloroethylene

QIANG Zhimin, BEN Weiwei, HUANG Chin-Pao

期刊论文

The effect of altering crosslinker chemistry during interfacial polymerization on the performance of nanofiltration membranes for desalination, organic, and micropollutants removal

期刊论文

Asymmetric transfer hydrogenation of prochiral ketone catalyzed over Fe-CS/SBA-15 catalyst

XUE Ping, WU Tao

期刊论文