SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Yinghao Shi,Dong Wang,Feilong Gao,Linan Liu,Qinglong Liu,Lan Wang,Jingchun Tang
The performance optimization of zero-valent iron (ZVI) based materials for reductive dechlorination remains challenging. After extensive research on sulfidation modification, the doping of heteroatom nitrogen (N) into ZVI for reductive dechlorination of chlorinated hydrocarbons (CHCs) becomes a new promising trend. In this study, surface modification of microscale ZVI (mZVI) was carried out by a facile ball milling method, and Fe–N(C) coated mZVI (abbreviated as N(C)-mZVI bm ) synthesized from different N sources of dimethylimidazole, urea and melamine were characterized. The effects of nitrogen-to-iron ratios (N/Fe), ball milling time and speed on the reductive dechlorination of trichloroethylene (TCE) were further investigated. A series of characterization and mechanistic analysis showed that the high reactivity of N(C)-mZVI bm with melamine as nitrogen source (abbreviated as N(C)-mZVI bm (M)) was attributed to the properties and thickness of its particle passivation layer, and faster electron transfer from the reduced iron species to the surface layer. In addition, N(C)-mZVI bm (M) exhibited great performance for dechlorination at a wide pH range of 3 to 11, due to alleviated passivation of the Fe 0 core under alkaline conditions by Fe–N(C). This study presents new ideas and evidences for the environmentally friendly synthesis of N-modified ZVI materials and their practical application in groundwater remediation.
研究领域:
环境科学
·
材料科学
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产品关联
DOI
高影响因子
Journal of Environmental Sciences
·
2023
·
IF 6.9
Yue Lu,Fangyi Liang,Fanzhi Qin,Linrui Zhong,Jianhong Jiang,Qi Liu,Shoujuan Zhang,Ming Yan,Changzheng Fan,Haoran Dong
The dehalogenation of organohalides has been a research hotspot in bioremediation field; however, the influence of tourmaline, a natural ore that can generate spontaneous electric field, on organohalide-respiring bacteria (OHRB) and their dechlorination process is not well known. In this study, the effect and mechanism of tourmaline on the reductive dechlorination of 2,3-dichlorophenol (2,3-DCP) by Desulfitobacterium hafniense DCB-2 T were explored. The characterization results confirmed that tourmaline had good stability and the optimal dosage of tourmaline was 2.5 g/L, which shortened the total time required for dechlorination reaction to 72 hr. Besides, tourmaline amendment also increased the proportion of 2-chlorophenol (2-CP) from 18% to 30% of end products, while that of 3-CP decreased correspondingly. The theoretical calculations showed that the bond charge of the ortho -substituted chlorine declined from -0.179 to -0.067, and that of meta -substituted chlorine increased from -0.111 to -0.129, which indicated that the spontaneous electric field of tourmaline affected the charge distribution of 2,3-DCP and was more conducive to the generation of 2-CP. Overall, tourmaline with the spontaneous electric field affected the reductive dechlorination pathway of Desulfitobacterium ,and the tourmaline-OHRB combining system might serve as a novel strategy for the bioremediation of environments polluted with chlorinated phenols.
研究领域:
环境科学
·
微生物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2019
·
IF 14.229
Jie Yu,Xiaoli Hou,Xiantao Hu,Hong Yuan,Jingyu Wang,Chuncheng Chen
Chloramphenicol (CAP) has been extensively used in the broad-spectrum antibiotic therapy so that its excessive emission has brought about serious contamination in aquatic environments. It is of great concern to find an efficient removal method and understand the transformation pathways. In this study, we developed the zero-valence iron based catalytic technique by synthesizing regular zero-valence iron microspheres (ZVI MPs), which could completely remove the CAP pollutant (20 mg L −1 ) within 15 min. When the CAP concentration increased to 50 mg L −1 , the removal efficiency achieved to 95.5% after 15 min of reaction. The chemical evolutions of iron species on the catalyst surface and changes in components of the solution demonstrated the activation of molecular oxygen and hydrogen ion by ZVI MPs. The generation of OH and H radicals as well as their contributions to CAP degradation were confirmed by electron spin resonance and trapping experiments during the reaction. Further experiments including the intermediates identification revealed a possible degradation pathway. To the best of our knowledge, the mechanism of CAP degradation by ZVI was proposed for the first time involving both reductive and oxidative transformations with a prerequisite of efficient reductive dechlorination. The complete dechlorination of CAP molecules was confirmed by the detection of inorganic Cl – concentration (0.124 mmol L −1 after reaction), which generally lowered the toxicity of the products. These findings not only provided an efficient and economic zero-valent iron technique for eliminating the antibiotic pollutants in water, but also made important contributions to better understand the removal mechanism.
研究领域:
环境科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2018
·
IF 3.927
Shenghua Chen,Wenhai Chu,Hongbin Wei,Hongying Zhao,Bin Xu,Naiyun Gao,Daqiang Yin
Haloacetamides (HAcAms), a class of highly toxic nitrogenous disinfection by-products (N-DBPs), have been widely detected in drinking water . The control of DBPs is an important measure to ensure the safety of drinking water. Due to the presence of residual chlorine and organic compounds that failed to be effectively removed, HAcAms could be formed in the finished drinking water distribution systems. In the study, Cu/Fe bimetal with different molar ratios of Cu to Fe was synthesized. This study reported that Cu/Fe bimetal reduced trichloroacetamide (TCAcAm) to dichloroacetamide (DCAcAm) and monoacetamide (MCAcAm), and the reduction ability of Fe was greatly improved due to the incorporation of Cu. The optimal HAcAm removal was achieved when the molar ratio of Cu to Fe was 2.0%, Cu/Fe bimetal could reach complete degradation of TCAcAm within 1 h. With the increase of Cu/Fe bimetal dose or the decrease of solution pH, the reduction ability of Cu/Fe bimetal for HAcAm removal also increased. The calculated integrated toxicity values from HAcAms, which was used to reflect the comprehensive control effect of Cu/Fe bimetal for HAcAms, were also reduced with the decrease of solution pH and the increase of bimetal dose. The release of Cu 2+ was not detected during the whole treatment process, Cu/Fe bimetal may be an excellent material for controlling DBPs as the end – control methods in tap water.
研究领域:
环境科学
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水处理工程
·
毒理学
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产品关联
DOI
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
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2018
·
IF 6.434
Jiafeng Ding,Gaoyuan Long,Yang Luo,Runze Sun,Mengxia Chen,Yajun Li,Yanfang Zhou,Xinhua Xu,Weirong Zhao
Polychlorinated dibenzo- p -dioxins (PCDDs), as a group of notorious anthropogenic environmental toxicants, are arguably ubiquitous in nature. In this study, we investigated the photocatalytic reductive dechlorination of 2-chlorodibenzo- p -dioxin (2-CDD) over Pd/g-C 3 N 4 catalysts under UV–vis irradiation. The g-C 3 N 4 and a series of Pd/g-C 3 N 4 catalysts were prepared by thermal polymerization and mechanical mixing-illumination method and characterized by XRD, TEM, BET, SEM and UV–vis DRS analyses. Among all the samples, the Pd/g-C 3 N 4 (5 wt%) yielded the optimal dechlorination activity with a total 2-CDD conversion of 54% within 4 h, and 76% of those converted 2-CDD were evolved to dibenzo- p -dioxin (DD). The kinetics of dechlorination could be described as pseudo-first-order decay model (R 2 > 0.84). Corresponding rate constants (k) increased from 0.052 to 0.17 h −1 with Pd contents up to 5 wt% and decreased to 0.13 h −1 with a 10 wt% of Pd. The enhanced activities originated from the surface plasmonic resonance (SPR) effect of Pd nanoparticles and the formation of Schottky barrier between Pd and g-C 3 N 4 , which extend the spectrum responsive range and suppress the charge recombination of g-C 3 N 4 . This is the first report on the photocatalytic reductive removal of PCDDs and may provide a new approach for PCDDs pollution control.
研究领域:
环境科学
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化学工程
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2020
·
IF 10.652
Fanxu Meng,Zhenjie Li,Cheng Lei,Kun Yang,Daohui Lin
Nanoscale zero-valent iron (nZVI) is widely studied for environmental remediation in recent years. However, its easy agglomeration, vulnerable oxidation, and runoff limit its practical application. Herein, iron-based lignin-derived biochar composites (Fe-LBC) with different Fe/C ratios were synthesized using a facile carbothermal reduction method and applied for trichloroethene (TCE) removal from anaerobic water. The synthesized Fe-LBC was equipped with higher specific surface area, more uniform nanoparticles distribution, and higher iron carbide content with the decrease of Fe/C ratio from about 1:5 (Fe-LBC 5 ) to 1:30 (Fe-LBC 30 ). TCE removal by Fe-LBC firstly increased as the Fe/C ratio increased from 1:10 6 to 1:10 3 , and then decreased with the Fe/C ratio further increased to 1:5. The removal efficiency remained largely stable (97.0–98.5%) within the Fe/C ratio range of 1:10 4 -1:30. Fe-LBC 30 (1.0 g L −1 ) could remove 97.4% of TCE (10.4 mg L −1 ), and owned the highest dechlorination efficiency (30.0%). Iron carbides but not Fe 0 could mainly contribute to the dechlorination. The quenching experiment reveals atomic hydrogen (H*) formed under the catalysis of iron carbides, and 1,2-dichloroethene was identified as the main degradation product derived from hydrogenolysis; electrochemical analyses suggest iron carbides could also serve as electron donors to TCE. Moreover, Fe-LBC 30 maintained excellent TCE removal efficiency in various water matrixes and pH range of 3–9, revealing its high application potential in practical groundwater remediation. This work firstly demonstrated the reductive dechlorination action of iron carbides rather than nZVI in iron-biochar hybrid materials, boosting our knowledge and potential application of iron-based materials.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
ACS Omega
·
2018
·
IF 0
Shenghong Kang,Guozhong Wang,Huijun Zhao,Weiping Cai
The remediation of soil contaminated by 1,1,1-trichloro-2,2-bis(4-chlorophenyl) ethane (DDT) has been a challenge. In this paper, the degradation performances of the ball milling-induced plate-like sub-microstructured zero valent iron (SMZVI) to DDT in a real soil environment is studied. It has been found that such SMZVI exhibits much higher degradation performances to DDT in soil than commercial ZVI powders under acidic conditions. More than 95% DDT could be degraded within 80 min in the 5 ppm DDT-contaminated soil with addition of 50 mg g–1 SMZVI, which is much better than the previously reported results. The time-dependent DDT removal amount can be well described by the pseudo first-order kinetic model. Further experiments have revealed that the ZVI dosages, surfactant’s and acidic additions, and the weight ratio of soil-to-water in the slurries are important to DDT degradation, and the degradation products were mainly DDD (a product with less chlorine). An acid-assisted ZVI-induced reductive dechlorination process is proposed, which can well explain the DDT degradation behaviors in soil and the influence from the other factors. This work not only deepens the understanding of DDT degradation in soils based on ZVI but also demonstrates that the SMZVI could be a promising material for DDT degradation in real environments.
研究领域:
环境科学
·
污染修复
✓ 已验证
产品关联
DOI
PubMed
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Yanqiang Tang,Ying Wang,Qingdong Qin,Yan Xu
In the anaerobic biocathode, reductive dechlorination of 2,4,6-trichlorophenol (2,4,6-TCP) mainly proceeded to produce 4-monochlorophenol (4-MCP) and phenol, while anaerobic mineralization was challenging. In this study, biocathodes microbial communities were first acclimated via potentials repeatedly adjusted between −0.278 V and +0.200 V (T-200), −0.278 V and +0.400 V (T-400), and −0.278 V and +0.600 V (T-600). Subsequently, all biocathode potentials were stabilized at −0.278 V for the degradation of 2,4,6-TCP. The results revealed that the T-600 achieved the highest degradation rate of 2,4,6-TCP (0.43 d −1 ), outperforming T-200 (0.051 d −1 ), T-400 (0.020 d −1 ), and open-circuit bioreactor (OC, 0.038 d −1 ) groups. In T-600, pare -dechlorination was facilitated, allowing for the conversion of 2,4,6-TCP to 2-monochlorophenol (2-MCP). Additionally, the detection of 4-hydroxybenzoic acid, an anaerobic mineralization intermediate of 2,4,6-TCP, indicated that anaerobic mineralization was also occurring. Polarity reversal occurred only in T-600 during the acclimation period, resulting in alterations to the electrical properties of the biocathode and microbial community. The cyclic voltammetry (CV) and differential pulse voltammetry (DPV) results indicated that there were more electroactive sites in biocathode of T-600, and the bidirectional extracellular electron transfer (EET) might be related to cytochrome. Mycobacterium (24.33% in slurry and 19.92% in biofilm), Thiobacillus (2.47% in slurry and 17.85% in biofilm), and Arenimonas (4.23% in slurry and 4.32% in cathode biofilm) were identified as the dominant electroactive bacteria in T-600, with Mycobacterium also playing an important role in the degradation of chlorophenols. These findings suggested that polarity reversal may represent a viable strategy for constructing microbial communities capable of achieving simultaneous dechlorination and mineralization of 2,4,6-TCP.
研究领域:
环境微生物学
·
电化学工程
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产品关联
DOI
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
Environmental Science-Nano
·
2024
·
IF 5.8
Zhoujie Pi,Puyu Zhou,Kun Luo,Li He,Shengjie Chen,Zhu Wang,Shanshan Zhang,Xiaoming Li,Qi Yang
Chlorophenols (CPs) have strong toxicity because of the presence of chlorine atoms. Although dechlorination can eliminate their toxicity, their by-products may cause secondary pollution. In this study, a two-step process of pre-reduction dechlorination and oxidation, reductive dechlorination by sulfidated nanoscale zero-valent iron (S-nZVI) and advanced oxidation by S-nZVI-activated peroxydisulfate (PDS), was innovatively adopted to achieve efficient and complete mineralization of 2,4-dichlorophenol (2,4-DCP). The pre-reduction of S-nZVI achieved 80% dechlorination of 2,4-DCP. With the subsequent addition of PDS, 2,4-DCP and its dechlorination by-products in the solution were almost completely removed, and the mineralization rate reached 91.5% under the optimal conditions of unadjusted initial pH (5.4), S-nZVI dosage 2.5 g L−1, and PDS concentration of 1.8 mM. The electron spin resonance (ESR) and radical quenching experiments demonstrated that both ·OH and SO4− were involved in the degradation of 2,4-DCP, while SO4− played a more predominant role. Based on the transformation products of 2,4-DCP identified by GC-MS, the degradation mechanism of 2,4-DCP in this system included two steps, namely, reductive dechlorination induced by electron transformation and oxidation degradation involving single electron transfer, radical adduct formation, and hydrogen atom abstraction. This study demonstrated that the novel S-nZVI pre-reduction and sequential S-nZVI/PDS process is a very promising and efficient approach for the complete removal of CPs in water.
研究领域:
环境科学
·
化学工程
✓ 已验证
DOI
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2024
·
IF 12.2
Wan Huang,Lifeng Cao,Runlei Ge,Ziren Wan,Di Zheng,Fangzhou Li,Guanghe Li,Fang Zhang
The coupling of thermal remediation with microbial reductive dechlorination (MRD) has shown promising potential for the cleanup of chlorinated solvent contaminated sites. In this study, thermal treatment and bioaugmentation were applied in series, where prior higher thermal remediation temperature led to improved TCE dechlorination performance with both better organohalide-respiring bacteria (OHRB) colonization and electron donor availability. The 60 °C was found to be a key temperature point where the promotion effect became obvious. Amplicon sequencing and co-occurrence network analysis demonstrated that temperature was a more dominating factor than bioaugmentation that impacted microbial community structure. Higher temperature of prior thermal treatment resulted in the decrease of richness, diversity of indigenous microbial communities, and simplified the network structure, which benefited the build-up of newcoming microorganisms during bioaugmentation . Thus, the abundance of Desulfitobacterium increased from 0.11 % (25 °C) to 3.10 % (90 °C). Meanwhile, released volatile fatty acids (VFAs) during thermal remediation functioned as electron donors and boosted MRD. Our results provided temperature-specific information on synergistic effect of sequential thermal remediation and bioaugmentation, which contributed to better implementation of the coupled technologies in chloroethene-impacted sites.
研究领域:
环境科学
·
微生物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
WATER RESEARCH
·
2024
·
IF 11.4
Yang Yu,Ang Li,Sheng-Qiang Fan,He-Ping Zhao
Dissimilatory iron-reducing bacteria (DIRB) with extracellular electron transfer (EET) capabilities have shown significant potential for bioremediating halogenated hydrocarbon contaminated sites rich in iron and humic substances. However, the role and microbial molecular mechanisms of iron-humic acid (Fe-HA) complexes in the reductive dehalogenation process of DIRB remains inadequately elucidated. In this study, we developed a sustainable carbon cycling approach using Fe-HA complexes to modulate the electron flux from sawdust (SD), enabling almost complete reductive dechlorination by most DIRB (e.g., Shewanella oneidensis MR-1) that lack complex iron-sulfur molybdo enzymes. The SD-Fe-HA/MR-1 system achieved a 96.52% removal efficiency of tetrachloroethylene (PCE) at concentrations up to 250 μmol/L within 60 days. Material characterization revealed that DIRB facilitated the hydrolysis of macromolecular carbon sources by inducing the formation of amorphous ferrihydrite (FeOOH) in Fe-HA complexes. More importantly, the bioavailable FeOOH activated additional intracellular electron flow pathways, increasing the activity of potential dehalogenases. Transcriptome further highlight the innovative role of biogenic amorphous FeOOH in integrating intracellular redox metabolism with extracellular charge exchange to facilitate reductive dechlorination in DIRB. These findings provide novel insights into accelerating reductive dechlorination in-situ contaminated sites lacking obligate dehalogenating bacteria.
研究领域:
环境微生物学
·
污染修复
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）