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Enhanced reductive degradation of carbon tetrachloride by carbon dioxide radical anion-based sodium percarbonate

Wenchao Jiang, Ping Tang, Shuguang Lu, Xiang Zhang, Zhaofu Qiu, Qian Sui

《环境科学与工程前沿(英文)》 2018年 第12卷 第2期 doi: 10.1007/s11783-017-0987-6

摘要: The performance of sodium percarbonate (SPC) activated with ferrous ion (Fe(II)) with the addition of formic acid (FA) to stimulate the degradation of carbon tetrachloride (CT) was investigated. Results showed that CT could be entirely reduced within 15 min in the system at a variety of SPC/Fe(II)/FA/CT molar ratios in experimental level. Scavenging tests indicated that carbon dioxide radical anion (CO2· ) was the dominant reactive oxygen species responsible for CT degradation. CT degradation rate, to a large extent, increased with increasing dosages of chemical agents and the optimal molar ratio of SPC/Fe(II)/FA/CT was set as 60/60/60/1. The initial concentration of CT can hardly affect the CT removal, while CT degradation was favorable in the pH range of 3.0–9.0, but apparently inhibited at pH 12. Cl and HCO of high concentration showed negative impact on CT removal. Cl released from CT was detected and the results confirmed nearly complete mineralization of CT. CT degradation was proposed by reductive C-Cl bond splitting. This study demonstrated that SPC activated with Fe(II) with the addition of FA may be promising technique for CT remediation in contaminated groundwater.

关键词: Carbon tetrachloride     Sodium percarbonate     Formic acid     Reductive radicals     Groundwater    

Integration of microbial reductive dehalogenation with persulfate activation and oxidation (Bio-RD-PAO

《环境科学与工程前沿(英文)》 2022年 第16卷 第2期 doi: 10.1007/s11783-021-1457-8

摘要:

•Bio-RD-PAO can effectively and extensively remove organohalides.

关键词: Bio-RD-PAO     Microbial reductive dehalogenation     Persulfate     Organohalide respiration     Complete attenuation    

Development and characterization of an anaerobic microcosm for reductive dechlorination of PCBs

Dawei Liang, Shanquan Wang

《环境科学与工程前沿(英文)》 2017年 第11卷 第6期 doi: 10.1007/s11783-017-0939-1

摘要: The toxic and recalcitrant polychlorinated biphenyls (PCBs) adversely affect human and biota by bioaccumulation and biomagnification through food chain. In this study, an anaerobic microcosm was developed to extensively dechlorinate hexa- and hepta-CBs in Aroclor 1260. After 4 months of incubation in defined mineral salts medium amended PCBs (70 mmol·L ) and lactate (10 mmol·L ), the culture dechlorinated hexa-CBs from 40.2% to 8.7% and hepta-CBs 33.6% to 11.6%, with dechlorination efficiencies of 78.3% and 65.5%, respectively (all in moL ratio). This dechlorination process led to tetra-CBs (46.4%) as the predominant dechlorination products, followed by penta- (22.1%) and tri-CBs (5.4%). The number of chlorines per biphenyl decreased from 2.50 to 1.41. Results of quantitative real-time PCR show that cells increased from 2.39 × 10 ±0.5 × 10 to 4.99 × 10 ±0.32 × 10 copies mL after 120 days of incubation, suggesting that play a major role in reductive dechlorination of PCBs. This study could prove the feasibility of anaerobic reductive culture enrichment for the dehalogenation of highly chlorinated PCBs, which is prior to be applied for in situ bioremediation of notorious halogenated compounds.

关键词: Polychlorinated biphenyls (PCBs)     Microbial reductive dechlorination     Dehalococcoides     Pathway    

Size and shape effects of MnFeO nanoparticles as catalysts for reductive degradation of dye pollutants

《环境科学与工程前沿(英文)》 2021年 第15卷 第5期   页码 108-171 doi: 10.1007/s11783-021-1396-4

摘要: The magnetic nanoparticles that are easy to recycle have tremendous potential as a suitable catalyst for environmental toxic dye pollutant degradation. Rationally engineering shapes and tailoring the size of nanocatalysts are regarded as an effective manner for enhancing performances. Herein, we successfully synthesized three kinds of MnFe2O4 NPs with distinctive sizes and shapes as catalysts for reductive degradation of methylene blue, rhodamine 6G, rhodamine B, and methylene orange. It was found that the catalytic activities were dependent on the size and shape of the MnFe2O4 NPs and highly related to the surface-to-volume ratio and atom arrangements. Besides, all these nanocatalysts exhibit selectivity to different organic dyes, which is beneficial for their practical application in dye pollutant treatment. Furthermore, the MnFe2O4 NPs could be readily recovered by a magnet and reused more than ten times without appreciable loss of activity. The size and shape effects of MnFe2O4 nanoparticles demonstrated in this work not only accelerate further understanding the nature of nanocatalysts but also contribute to the precise design of nanoparticles catalyst for pollutant degradation.

关键词: Dye degradation     MnFe2O4 nanoparticles     Size and shape-control    

Decontamination of Cr(VI) facilitated formation of persistent free radicals on rice husk derived biochar

Kaikai Zhang, Peng Sun, Yanrong Zhang

《环境科学与工程前沿(英文)》 2019年 第13卷 第2期 doi: 10.1007/s11783-019-1106-7

摘要:

PFRs were produced on biochar during Cr(VI) decontamination.

PFRs formation on biochar was owing to the oxidization of phenolic-OH by Cr(VI).

Appearance of excessive oxidant led to the consumption of PFRs on biochar.

Biochar charred at high temperature possessed great performance to Cr(VI) removal.

关键词: Biochar     Persistent free radicals     Phenolic hydroxyl groups     Cr(VI) reduction    

Light-induced variation in environmentally persistent free radicals and the generation of reactive radical

Yafang Shi, Yunchao Dai, Ziwen Liu, Xiaofeng Nie, Song Zhao, Chi Zhang, Hanzhong Jia

《环境科学与工程前沿(英文)》 2020年 第14卷 第6期 doi: 10.1007/s11783-020-1285-2

摘要: Abstract • Light irradiation increased the concentration of free radicals on HS. • The increased spin densities on HS readily returned back to the original value. • The “unstable” free radicals induced the formation of reactive radical species. • Reactive radicals’ concentration correlated strongly with EPFRs’ concentration. Environmentally persistent free radicals (EPFRs) in humic substances play an essential role in soil geochemical processes. Light is known to induce EPFRs formation for dissolved organic matter in aquatic environments; however, the impacts of light irradiation on the variation of EPFRs in soil humic substances remain unclear. In this study, humic acid, fulvic acid, and humin were extracted from peat soil and then in situ irradiated using simulated sunlight. Electron paramagnetic resonance spectroscopy results showed that with the increasing irradiation time, the spin densities and g-factors of humic substances rapidly increased during the initial 20 min and then gradually reached a plateau. After irradiation for 2h, the maximum spin density levels were up to 1.63 × 1017, 2.06 × 1017, and 1.77 × 1017 spins/g for the humic acid, fulvic acid, and humin, respectively. And the superoxide radicals increased to 1.05 × 1014–1.46 × 1014 spins/g while the alkyl radicals increased to 0.47 × 1014–1.76 × 1014 spins/g. The light-induced EPFRs were relatively unstable and readily returned back to their original state under dark and oxic conditions. Significant positive correlations were observed between the concentrations of EPFRs and reactive radical species (R2 = 0.65–0.98, p<0.05), which suggested that the newly produced EPFRs contributed to the formation of reactive radical species. Our findings indicate that under the irradiation humic substances are likely to be more toxic and reactive in soil due to the formation of EPFRs.

关键词: Peat     Humic substances     Environmentally persistent free radicals     Light irradiation     Reactive radical species    

Competition for electrons between reductive dechlorination and denitrification

Lifeng Cao, Weihua Sun, Yuting Zhang, Shimin Feng, Jinyun Dong, Yongming Zhang, Bruce E. Rittmann

《环境科学与工程前沿(英文)》 2017年 第11卷 第6期 doi: 10.1007/s11783-017-0959-x

摘要: It is common that 2,4,6-trichlorophenol (TCP) coexists with nitrate or nitrite in industrial wastewaters. In this work, simultaneous reductive dechlorination of TCP and denitrification of nitrate or nitrite competed for electron donor, which led to their mutual inhibition. All inhibitions could be relieved to a certain degree by augmenting an organic electron donor, but the impact of the added electron donor was strongest for TCP. For simultaneous reduction of TCP together with nitrate, TCP’s removal rate value increased 75% and 150%, respectively, when added glucose was increased from 0.4 mmol·L to 0.5 mmol·L and to 0.76 mmol·L . For comparison, the removal rate for nitrate increased by only 25% and 114% for the same added glucose. The relationship between their initial biodegradation rates versus their initial concentrations could be represented well with the Monod model, which quantified their half-maximum-rate concentration ( value), and values for TCP, nitrate, and nitrite were larger with simultaneous reduction than independent reduction. The increases in are further evidence that competition for the electron donor led to mutual inhibition. For bioremediation of wastewater containing TCP and oxidized nitrogen, both reduction reactions should proceed more rapidly if the oxidized nitrogen is nitrite instead of nitrate and if readily biodegradable electron acceptor is augmented.

关键词: Competition for electrons     Denitrification     Reductive dechlorination     Bioremediation     Nitrate     2     4     6-trichlorophenol    

Kinetics and mechanism of nitrobenzene degradation by hydroxyl radicals-based ozonation process enhanced

Weizhou Jiao, Shengjuan Shao, Peizhen Yang, Kechang Gao, Youzhi Liu

《化学科学与工程前沿(英文)》 2021年 第15卷 第5期   页码 1197-1205 doi: 10.1007/s11705-020-1998-6

摘要: This study investigated the indirect oxidation of nitrobenzene (NB) by hydroxyl radicals (·OH) in a rotating packed bed (RPB) using competitive kinetics method with -nitrochlorobenzene as a reference compound. The rate constants of NB with ·OH are calculated to be between (1.465±0.113) × 10 L/(mol·s) and (2.497±0.192) × 10 L/(mol·s). The experimental data are fitted by the modified Arrhenius equation, where the activation energy is 4877.74 J/mol, the order of NB concentration, rotation speed, and initial pH is 0.2425, 0.1400 and 0.0167, respectively. The ozonation process of NB could be enhanced by RPB, which is especially effective for highly concentrated NB-containing wastewater under alkaline conditions. The high gravity technology can accelerate ozone mass transfer and self-decomposition of ozone to produce more ·OH, resulting in an increase in the indirect oxidation rate of NB by ·OH and consequently effective degradation of NB in wastewater.

关键词: high gravity technology     hydroxyl radicals     nitrobenzene     reaction kinetics    

Regulation of radicals by hydrogen-donor solvent in direct coal liquefaction

《化学科学与工程前沿(英文)》 2022年 第16卷 第12期   页码 1689-1699 doi: 10.1007/s11705-022-2186-7

摘要: Radicals are important intermediates in direct coal liquefaction. Certain radicals can cause the cleavage of chemical bonds. At high temperatures, radical fragments can be produced by the splitting of large organic molecules, which can break strong chemical bonds through the induction pyrolysis of radicals. The reaction between the formation and annihilation of coal radical fragments and the effect of hydrogen-donor solvents on the radical fragments are discussed in lignite hydrogenolysis. Using the hydroxyl and ether bonds as indicators, the effects of different radicals on the cleavage of chemical bond were investigated employing density functional theory calculations and lignite hydrogenolysis experiments. Results showed that the adjustment of the coal radical fragments could be made by the addition of hydrogen-donor solvents. Results showed that the transition from coal radical fragment to H radical leads to the variation of product distribution. The synergistic mechanism of hydrogen supply and hydrogenolysis of hydrogen-donor solvent was proposed.

关键词: direct coal liquefaction     hydrogen-donor solvent     induced pyrolysis     radical mechanism     density functional theory calculations    

Fluoroalcohol-mediated reductive iodonio-Claisen rearrangement: Synthesis of complex

Hem Raj Khatri,Hai Nguyen,James K. Dunaway,Jianglong Zhu

《化学科学与工程前沿(英文)》 2015年 第9卷 第3期   页码 359-368 doi: 10.1007/s11705-015-1530-6

摘要: Reductive iodonio-Claisen rearrangement (RICR) involving -iodanes and allyl or substituted-allyl silanes in fluoroalcohols, such as 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) and 2,2,2-trifluoroethanol (TFE), was studied for the synthesis of complex -allyl or substituted-allyl iodoarenes. In comparison to the previously reported condition involving boron trifluoride diethyl etherate, the RICR mediated by fluoroalcohols was found to proceed more effectively. The resulting complex -allyl iodoarenes are useful synthetic intermediates and can be readily converted to various heterocyclic compounds.

关键词: hypervalent iodine     allylation     fluoroalcohol     Claisen rearrangement     heterocycles    

Persistent free radicals in humin under redox conditions and their impact in transforming polycyclic

Hanzhong Jia, Yafang Shi, Xiaofeng Nie, Song Zhao, Tiecheng Wang, Virender K. Sharma

《环境科学与工程前沿(英文)》 2020年 第14卷 第4期 doi: 10.1007/s11783-020-1252-y

摘要: Abstract • Regulation of redox conditions promotes the generation of free radicals on HM. • HM-PFRs can be fractionated into active and inactive types depending on stability. • The newly produced PFRs readily release electrons to oxygen and generate ROS. • PFR-induced ROS mediate the transformation of organic contaminants adsorbed on HM. The role of humic substance-associated persistent free radicals (PFRs) in the fate of organic contaminants under various redox conditions remains unknown. This study examined the characterization of original metal-free peat humin (HM), and HM treated with varying concentrations of H2O2 and L-ascorbic acid (VC) (assigned as H2O2-HM and VC-HM). The concentration of PFRs in HM increased with the addition of VC/H2O2 at concentrations less than 0.08 M. The evolution of PFRs in HM under different environmental conditions (e.g., oxic/anoxic and humidity) was investigated. Two types of PFRs were detected in HM: a relatively stable radical existed in the original sample, and the other type, which was generated by redox treatments, was relatively unstable. The spin densities of VC/H2O2-HM readily returned to the original value under relatively high humidity and oxic conditions. During this process, the HM-associated “unstable” free radicals released an electron to O2, inducing the formation of reactive oxygen species (ROS, i.e., •OH and •O2−). The generated ROS promoted the degradation of polycyclic aromatic hydrocarbons based on the radical quenching measurements. The transformation rates followed the order naphthalene>phenanthrene>anthracene>benzo[a]pyrene. Our results provide valuable insight into the HM-induced transformation of organic contaminants under natural conditions.

关键词: Humic substance     Polycyclic aromatic hydrocarbons (PAHs)     Persistent free radicals (PFRs)     Redox     Reactive oxygen species (ROS)    

Reductive amination of -hexanol to -hexylamine over Ni–Ce/-AlO catalysts

《化学科学与工程前沿(英文)》 2023年 第17卷 第1期   页码 82-92 doi: 10.1007/s11705-022-2181-z

摘要: The amination of alkyl alcohols is one of the most promising paths in synthesis of aliphatic amines. Herein, cerium doped nickel-based catalysts were synthesized and tested in a gas-phase amination of n-hexanol to n-hexylamine. It was found that the activity of the Ni/γ-Al2O3 catalyst is significantly improved by doping an appropriate amount of cerium. The presence of cerium effectively inhibits the agglomeration of nickel particle, resulting in better Ni dispersion. As Ni particle size plays critical role on the catalytic activity, higher turnover frequency of n-hexanol amination was achieved. Cerium doping also improves the reduction ability of nickel and enhances the interactions between Ni and the catalyst support. More weak acid sites were also found in those cerium doped catalysts, which promote another key step—ammonia dissociative adsorption in this reaction system. The overall synergy of Ni nanoparticles and acid sites of this Ni–Ce/γ-Al2O3 catalyst boosts its superior catalytic performance in the amination of n-hexanol.

关键词: amination     alcohol     cerium     nickel     acidity     interaction    

Bacteria inactivation by sulfate radical: progress and non-negligible disinfection by-products

《环境科学与工程前沿(英文)》 2023年 第17卷 第3期 doi: 10.1007/s11783-023-1629-9

摘要:

● Status of inactivation of pathogenic microorganisms by SO4•− is reviewed.

关键词: Sulfate radicals     Disinfection by-products     Inactivation mechanisms     Bacterial inactivation     Water disinfection    

NADPH oxidase and reactive oxygen species as signaling molecules in carcinogenesis

Gang WANG

《医学前沿(英文)》 2009年 第3卷 第1期   页码 1-7 doi: 10.1007/s11684-009-0018-5

摘要: Reactive oxygen species (ROS) are small molecule metabolites of oxygen that are prone to participate in redox reactions their high reactivity. Intracellular ROS could be generated in reduced nicotinamide-adenine dinucleotidephosphate (NADPH) oxidase-dependent and/or NADPH oxidase-independent manners. Physiologically, ROS are involved in many signaling cascades that contribute to normal processes. One classical example is that ROS derived from the NADPH oxidase and released in neurotrophils are able to digest invading bacteria. Excessive ROS, however, contribute to pathogenesis of various human diseases including cancer, aging, dimentia and hypertension. As signaling messengers, ROS are able to oxidize many targets such as DNA, proteins and lipids, which may be linked with tumor growth, invasion or metastasis. The present review summarizes recent advances in our comprehensive understanding of ROS-linked signaling pathways in regulation of tumor growth, invasion and metastasis, and focuses on the role of the NADPH oxidase-derived ROS in cancer pathogenesis.

关键词: free radicals     tumor     phox     cell proliferation     cancer therapy    

NOx and H2S formation in the reductive zone of air-staged combustion of

Jinzhi CAI, Dan LI, Denggao CHEN, Zhenshan LI

《能源前沿(英文)》 2021年 第15卷 第1期   页码 4-13 doi: 10.1007/s11708-020-0804-y

摘要: Low NO combustion of blended coals is widely used in coal-fired boilers in China to control NO emission; thus, it is necessary to understand the formation mechanism of NO and H S during the combustion of blended coals. This paper focused on the investigation of reductive gases in the formation of NO and H S in the reductive zone of blended coals during combustion. Experiments with Zhundong (ZD) and Commercial (GE) coal and their blends with different mixing ratios were conducted in a drop tube furnace at 1200°C–1400°C with an excessive air ratio of 0.6–1.2. The coal conversion and formation characteristics of CO, H S, and NO in the fuel-rich zone were carefully studied under different experimental conditions for different blend ratios. Blending ZD into GE was found to increase not only the coal conversion but also the concentrations of CO and H S as NO reduction accelerated. Both the CO and H S concentrations inblended coal combustion increase with an increase in the combustion temperature and a decrease in the excessive air ratio. Based on accumulated experimental data, one interesting finding was that NO and H S from blended coal combustion were almost directly dependent on the CO concentration, and the CO concentration of the blended coal combustion depended on the single char gasification conversion.Thus, CO, NO , and H S formation characteristics from blended coal combustion can be well predicted by single char gasification kinetics.

关键词: blended coal combustion     NOx formation     H2S formation     air staged combustion    

标题 作者 时间 类型 操作

Enhanced reductive degradation of carbon tetrachloride by carbon dioxide radical anion-based sodium percarbonate

Wenchao Jiang, Ping Tang, Shuguang Lu, Xiang Zhang, Zhaofu Qiu, Qian Sui

期刊论文

Integration of microbial reductive dehalogenation with persulfate activation and oxidation (Bio-RD-PAO

期刊论文

Development and characterization of an anaerobic microcosm for reductive dechlorination of PCBs

Dawei Liang, Shanquan Wang

期刊论文

Size and shape effects of MnFeO nanoparticles as catalysts for reductive degradation of dye pollutants

期刊论文

Decontamination of Cr(VI) facilitated formation of persistent free radicals on rice husk derived biochar

Kaikai Zhang, Peng Sun, Yanrong Zhang

期刊论文

Light-induced variation in environmentally persistent free radicals and the generation of reactive radical

Yafang Shi, Yunchao Dai, Ziwen Liu, Xiaofeng Nie, Song Zhao, Chi Zhang, Hanzhong Jia

期刊论文

Competition for electrons between reductive dechlorination and denitrification

Lifeng Cao, Weihua Sun, Yuting Zhang, Shimin Feng, Jinyun Dong, Yongming Zhang, Bruce E. Rittmann

期刊论文

Kinetics and mechanism of nitrobenzene degradation by hydroxyl radicals-based ozonation process enhanced

Weizhou Jiao, Shengjuan Shao, Peizhen Yang, Kechang Gao, Youzhi Liu

期刊论文

Regulation of radicals by hydrogen-donor solvent in direct coal liquefaction

期刊论文

Fluoroalcohol-mediated reductive iodonio-Claisen rearrangement: Synthesis of complex

Hem Raj Khatri,Hai Nguyen,James K. Dunaway,Jianglong Zhu

期刊论文

Persistent free radicals in humin under redox conditions and their impact in transforming polycyclic

Hanzhong Jia, Yafang Shi, Xiaofeng Nie, Song Zhao, Tiecheng Wang, Virender K. Sharma

期刊论文

Reductive amination of -hexanol to -hexylamine over Ni–Ce/-AlO catalysts

期刊论文

Bacteria inactivation by sulfate radical: progress and non-negligible disinfection by-products

期刊论文

NADPH oxidase and reactive oxygen species as signaling molecules in carcinogenesis

Gang WANG

期刊论文

NOx and H2S formation in the reductive zone of air-staged combustion of

Jinzhi CAI, Dan LI, Denggao CHEN, Zhenshan LI

期刊论文