ENVIRONMENTAL POLLUTION
·
2021
·
IF 8.071
Na Liu,Qing Hu,Chao Wang,Lizhi Tong,Chih-Huang Weng,Longzhen Ding
This study demonstrated that nitrogen-doped carbon materials (NCMs) could effectively catalyze the chlorine elimination process in hexachloroethane (HCA) declorination in sulfide-containing environments for the first time. The k obs values of HCA dechlorination by sulfide in the presence of 10 mg/L NCMs were higher than that of no mediator at pH 7.3 by one or two orders of magnitude. The catalytic capabilities of NCMs on HCA dechlorination were evident in common ranges of natural pH (5.3–8.9) and it could be accelerated by the increase of pH but be suppressed by the presence of dissolved humic acid . Moreover, NCMs exhibited much better catalytic capability on HCA dechlorination compared to the carbon materials, mainly owing to the combined contributions of pyridine N, including enhanced nucleophilic attack to HCA molecule by generating newborn C–S–S and activation of HCA molecule by elongating C–Cl bonds. The functions of pyridine N in micron-sized NCMs with mesopores were better than in nano-sized NCMs on HCA dechlorination. These findings displayed the potential of NCMs, when released into sulfide-containing environments, may significantly increase the dechlorination of chlorinated aliphatic hydrocarbons.
研究领域:
环境科学
·
催化化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2018
·
IF 4.61
Jun Hu,Zhiyong Huang,Jianming Yu
In this study, Fe/Fe 3 O 4 mixture was first applied as an additive to achieve the highly-effective mechanochemical destruction (MCD) of two halogenated organic pollutants (HOPs), hexachloroethane (HCE) and hexachlorobenzene (HCB). The MCD of HCE was more effective than that of HCB in virtue of the lower dissociation energy of C Cl bond. The MCD of HOPs occurred mainly via the reduction by Fe, Fe 3 O 4 and Fe/Fe 3 O 4 . The oxidation of Fe 3 O 4 and reduction of FeO (formed on account of the oxidation of Fe by oxygen-containing species) may also contribute to the HOP destruction. Fe/Fe 3 O 4 mixture exhibited a higher dechlorination rate (DR) than other three effective additives (i.e., Fe/SiO 2 , Al/Al 2 O 3 and Mg/Al 2 O 3 mixture), owing to the electrical property of Fe 3 O 4 and its electron transfer with Fe. The HOP destruction was significantly impacted by the mass fraction of Fe 3 O 4 (MF mag ) and achieved the maximum level with an MF mag of 70%. The DR of HOPs in the atmosphere of air was higher than those of pure oxygen and nitrogen because of the oxygen vacancy in Fe 3 O 4 and oxidation of Fe. The presence of water dramatically inhibited the HOP destruction due to the decrease of collision energy and its competition for the active sites in both Fe and Fe 3 O 4 . As expected, the DR of HOPs increased with rotation speed, and the mass ratio of ball to reactant and additive to pollutant. The analysis of intermediates indicates that HCB destruction was mainly via dechlorination and polymerization, while HCl cleavage also played an important role in HCE destruction. The results demonstrate that Fe/Fe 3 O 4 mixture is a suitable additive for MCD process.
研究领域:
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Environmental Science-Processes & Impacts
·
2020
·Vol. 22
·期 9
·1898-1907
·
IF 3.238
Shujun Yin,Chenhui Wei,Dongqiang Zhu
Understanding the mechanisms controlling the redox transformation of organic contaminants mediated by biochar is of great significance for application of biochar in remediation of contaminated soils and sediments. Here we investigated the mediation effect of a pine wood-derived biochar (P-char) in comparison with multiwalled carbon nanotubes (MCNTs) and graphite on the reductive dechlorination of hexachloroethane by sulfide. Upon normalization of the mediator's surface area, the reduction rate of hexachloroethane follows an order of P-char < MCNTs < graphite. Aqueous polysulfides and polysulfide free radicals were readily produced by reacting sulfide only with P-char, and the supernatant separated from the reaction system could account for 83.4% of the pseudo-kinetic rate constant of hexachloroethane mediated by P-char. In contrast, MCNTs and graphite had weak abilities to produce reactive sulfur species, and the supernatant exhibited very low reduction capability (<20.7%) of hexachloroethane. Electron paramagnetic resonance (EPR) analysis demonstrated that the surface quinone moieties on P-char induced the formation of polysulfides and polysulfide free radicals from sulfide by serving as one-electron acceptors. Consistently, polysulfides prepared by reacting elemental sulfur with sulfide showed much stronger reducing capability compared to sulfide. Thus, the mediation effect of P-char was dominantly attributed to the surface quinone-induced formation of reactive reducing sulfur species, whereas the mediation effect of MCNTs and graphite mainly stemmed from the enhanced electron transfer by the graphitized carbon. These results showed for the first time that surface quinone-induced formation of aqueous reactive sulfur species could control biochar-mediated reductive dechlorination of chloroorganic contaminants by sulfides.
研究领域:
环境科学
·
污染修复
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2025
·
IF 11.3
Xiaolei Wang,Mingquan Huang,Yunping Tong,Changyin Zhu,Fengxiao Zhu,Ning Chen,Dongmei Zhou
Carbon tetrachloride (CT, CCl₄) is one typical persistent organochlorine pollutant, which is refractory to be degraded in environment due to its strong chemical inertness. In this study, organic acids were introduced into the thermal activated persulfate (PS) system, which would react with oxidative radicals to generate reductive radicals, promoting the rapid degradation of CT. The results showed that formic acid (FA) enhanced the degradation rate by 3.38 times compared to the PS system alone, and the reductive degradation dominated in this process. Electron paramagnetic resonance (EPR) spectra, quenching experiments, and probe trapping confirmed that carbon dioxide radicals (CO 2 •- ) was the primary reactive specie responsible for CT degradation. This system can achieve great effect on a variety of soils with different properties. Furthermore, the microbial community analysis of soil revealed that the thermal/PS/FA system caused less disruption on soil microbiome and promoted faster microbial recovery than thermal/PS systems. This study proposes a green and efficient technology for remediating CT-contaminated soils. The thermal/PS/FA system mitigates adverse effects on soil microbial communities and accelerates ecosystem recovery, underscoring its potential as a sustainable technology for environmental pollution treatment.
研究领域:
环境科学
·
化学修复
·
土壤污染
·
自由基化学
·
微生物生态学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
APPLIED CATALYSIS A-GENERAL
·
2014
·
IF 3.674
Siyang Tang,Zhen Liu,Xiaowei Yan,Ning Li,Ruihua Cheng,Xuelian He,Boping Liu
An extensive experimental kinetic study of ethylene trimerization was carried out over the Chevron-Phillips homogeneous catalyst system [Cr(2-ethylhexanoate) 3 (Cr(2-EH) 3 )/2,5-dimethylpyrrole (DMP)/co-catalyst/halide] in terms of the effects from organic halide additives, type of co-catalysts, temperature, ethylene pressure, Cr concentration, and ligand/Cr molar ratio, etc. Ten kinds of organic halides and four kinds of organometallic co-catalysts were tested in this work. The 1,1,2,2-tetrachloroethane (TCE) and triethylaluminum (TEA) were found to be the best candidates for this catalyst system. The molar ratios of DMP/Cr, TCE/Cr and TEA/Cr showed a strong impact on the catalytic performance of ethylene trimerization. A detailed catalytic kinetic behavior and the kinetic simulation were also performed for the first time over this catalyst system. It could be extrapolated that the dependency of the trimerization reaction rate on ethylene concentration and catalyst concentration is second-order and first-order, respectively. The apparent activation energy of this reaction is 99.1 kJ/mol at the temperature range from 65 °C to 95 °C. And the apparent reaction rate equation is achieved as follows:. R = 5.23 × 10 18 exp − 99.1 R T C ca 1.12 C e 1.95 .
研究领域:
化学工程
·
催化科学
✓ 已验证
产品关联
DOI
高影响因子
Materials Today Communications
·
2021
·
IF 3.383
Yanqing Xue,Bo Li,Xinliang Wang,Xinlei Li,Han Zhang,Qitang Hao
Agglomeration behavior of TiB 2 particles in 5%TiB 2 /Al-4.5%Cu composites (all compositions are in wt.% unless otherwise specified) is studied by adding different content of Mg to improve its strength and ductility, a widely used in-situ molten salt reaction process is used to produce the composites. The results show that addition of Mg could not only significantly segregate TiB 2 particles but also further refine the α-Al grains and then improve the mechanical properties of the composites on the basis of TiB 2 particles. Here, 0.5% Mg is considered the optimum mass fraction for dispersion, refinement, and modification of particles based on the results of investigation. The yield strength (YS), ultimate tensile strength (UTS), elastic Young’s modulus (EM), and Vicker’s hardness (VHN) of the composites in T6 heat treatment are increased to 375 MPa, 486 MPa, 88 GPa, and 167 HV - an improvement of 21.8%, 16.5%, 20.9%, and 9.4%, respectively, versus the original TiB 2 /Al-4.5%Cu composite (308 MPa, 417 MPa, 63 GPa, and 153 HV). The elongation of the composite is improved by 20.9%. These merits are mainly attributed to addition of Mg, which increases the surface-spread coefficient of TiB 2 particles by reducing the surface tension of the Al melt, thereby improving the wettability .
研究领域:
材料科学
·
机械工程
✓ 已验证
产品关联
DOI
高影响因子
MATERIALS & DESIGN
·
2022
·
IF 9.417
Yanqing Xue,Qitang Hao,Xinlei Li,Han Zhang,Peiqing Wang,Chengze Yin,Bo Li,Xinliang Wang
The strength-ductility trade-off severely limits the extensive application of particle-reinforced aluminum matrix composites mainly owing to the critical issues of local particle agglomeration and poor interfacial characteristics. The present work concentrates on these intractable puzzles and proposes Mg-Ag microalloying TiB 2 /Al-4.5Cu composites fabricated by an optimized salt-metal reaction method and multistage heat treatment. The resulting microstructure evidence that this new tactic synergistically ameliorates the detrimental agglomeration of TiB 2 particles by Mg and Ag doped at the TiB 2 /α-Al interface， meanwhile promoting the formation of nanosized Ω-Al 2 Cu and σ-Al 5 Cu 6 Mg 2 phases. The mechanical property experimental results indicate that the Mg-Ag microalloyed TiB 2 /Al-4.5Cu composites exhibit an accredited combination of the tensile strength (ultimate tensile strength is 496.3 ± 15.0 MPa) and ductility (uniform elongation is 12.8 ± 1.4 %). We emphasize the reciprocal effect between TiB 2 particles and the precipitated phase associated with unrelaxed misfit strains. Close attention is also paid to the interface binding characteristics and semi-coherent interphase boundary to evaluate their contribution to the ductility. The microalloying strategy can potentially be applied to many other metal matrix composites and boost analogous approaches for designing ultrahigh yet ductile materials for technological applications.
研究领域:
材料科学
·
金属学
✓ 已验证
产品关联
DOI
高影响因子
CHINESE JOURNAL OF CATALYSIS
·
2023
·
IF 16.5
Changcheng Wei,Wenna Zhang,Kuo Yang,Xiu Bai,Shutao Xu,Jinzhe Li,Zhongmin Liu
ABSTRACT The most promising method to eliminate CO 2 is to find large-scale and value-added applications of CO 2 as a carbon resource. However, the utilization of CO 2 as feedstock for basic chemicals has long been a great challenge owing to its high thermodynamic stability. Herein, we report the coupling conversion of CO 2 with light alkanes over the HZSM-5 zeolite with much higher aromatic selectivity than light alkanes as the only reactant. A CO 2 conversion of 17.5% and n -butane conversion of 100% with aromatic selectivity of 80% could be achieved by the coupling reaction at the CO 2 to n -butane ratio of 0.475, in which CO 2 not only acted as an agent for balancing hydrogen in the reaction but also partly (~25%) incorporated into the aromatic products. Methyl-substituted lactones (MLTOs) and methyl-substituted cycloalkenones (MCEOs) were identified as key intermediates during the coupling reaction. 13 C isotope labeling experiments, 13 C solid-state NMR, in-situ diffuse reflectance infrared Fourier transform spectroscopy, and density functional theory (DFT)calculations revealed that CO 2 could react with carbonium ions generated from alkane cracking to form MLTOs, which could further get converted into MCEOs, thus generating aromatic compounds . This coupling reaction provides guidance for the direct utilization of CO 2 to produce value-added chemicals with the simultaneous transformation of light alkanes.
研究领域:
化学工程
·
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
ACS Sustainable Chemistry & Engineering
·
2023
·
IF 8.4
Changcheng Wei,Jinzhe Li,Zhongmin Liu
The utilization of renewable biomass using γ-valerolactone (GVL) as a platform is a sustainable and important route for the production of valuable chemicals. Herein, the selective transformation of GVL to 1,3-butadiene over zeolite catalysts under ambient pressure and continuous flow conditions was reported. Effects of zeolite topologies, acid density, reaction temperature, and contact time on the GVL conversion were systematically investigated. A 1,3-butadiene selectivity of 71% and GVL conversion of 100% were achieved over the NaZSM-35 catalyst at 400 °C. Further investigations revealed that the GVL-to-butadiene reaction might proceed by the following reaction route: GVL was first converted to pentenoic acid (PEA) and then dehydrated into acylium ions, further converting to 1,3-butadiene by decarbonylation. This work provided a promising route for the sustainable and selective production of 1,3-butadiene from renewable materials.
研究领域:
催化化学
·
可再生资源利用
·
绿色化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）