CHEMOSPHERE
·
2022
·
IF 8.943
Zhenzhen Yao,Xiaoman He,Qian Wang,Chao Wang,Qing Shi,Qiwu Zhang
This study explored a possible destruction of hexachlorobenzene (HCB) as example of persistent organic pollutants (POPs) as well as the dechlorination mechanism by directly using minerals in the soil, such as antigorite , talc and olivine. Compared with a stable quartz phase of SiO 2 , all three Mg silicate minerals demonstrated certain degrading capacity for HCB with different efficiency order as: antigorite > talc > olivine > SiO 2 at 2 h of milling time. Interestingly, olivine exhibited a better performance than antigorite at 4 h of milling time, giving destruction percentage of 92.7% over 89.0% even at high concentrated HCB up to 5% added. Raman and ESR characterizations of the ball milled sample with olivine indicated the formation of amorphous carbon and graphitic carbon, and the occurrence of free radicals was observed to play an important role in dechlorination and carbonization of HCB. The first identified effectiveness of directly using Mg silicate minerals, allowed no addition of active chemicals during the ball milling, therefore avoided the concern over extrinsic contaminations on the soil. Olivine was further utilized to deal with actual contaminated soil and showed unique advantages on application prospects.
研究领域:
环境科学
·
化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHEMOSPHERE
·
2016
·
IF 3.698
Shizong Wang,Yanan Yin,Jianlong Wang
Triclosan is an antimicrobial agent which has been frequently detected in the environment. In this paper, the biodegradation of triclosan after radiation-induced advanced oxidation was investigated. The results show that the removal efficiency of triclosan in the combined irradiation and biological treatment process ranged from 88% to 97%, depending on the absorbed dose, while it was only 54% in the single biological treatment process. The removal efficiency of total organic carbon (TOC) was in the range of 53.1%,−59.2% at dose of 1–5 kGy in the combined irradiation and biological treatment process. In comparison, the removal efficiency of TOC in the single biological treatment process was 24.5%, suggesting that irradiation can enhance the mineralization of triclosan. The dechlorination efficiency of triclosan ranged from 48.6% to 78.4% at dose of 1–5 kGy. The intermediates of triclosan degradation were tentatively identified by LC-MS analysis and the possible degradation pathway was proposed. Based on the above results, the combined irradiation and biological treatment process could be an alternative process for treating triclosan-containing wastewater.
研究领域:
环境科学
·
生物学
✓ 已验证
DOI
高影响因子
WATER RESEARCH
·
2025
·
IF 12.4
Jianqiao Xu,Xinyuan Wei,Junyan Wei,Mengqiang He,Xiaolei Teng,Zunyao Wang,Ruijuan Qu
While the reaction mechanism of direct photochemical dechlorination has been extensively studied, significant knowledge gaps remain regarding the specific roles of reactive species in governing dechlorination pathways during indirect photodegradation. By integrating mass spectrometry analysis, probe experiments and theoretical calculations, we propose for the first time an indirect dechlorination reaction mechanism for PCB-209 involving active species commonly found in DOM photosensitive systems, which differs significantly from that of direct photodegradation. Due to the lower bond energy of the C Cl bond at the position opposite the carbon bridge, PCB-209 primarily yielded PCB-208 in direct dechlorination systems. However, our study revealed that active species ( 3 DOM*, •O 2 − and 1 O 2 ) can specifically weaken the meta-positioned C Cl bond at the carbon bridge through electron transfer and cycloaddition mechanisms, thereby fundamentally altering the regioselectivity of dechlorination. Remarkably, our results confirm the indirect degradation of PCB-209 through DOM photosensitization to form dechlorination products dominated by PCB-207, a previously unrecognized transformation pathway in natural photochemical processes. This study refines the mechanism of indirect dechlorination mediated by reactive species and provides a predictive framework for the environmental fate of halogenated pollutants in real complex environmental systems.
研究领域:
环境科学
·
化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
RSC Advances
·
2016
·Vol. 6
·期 80
·76867-76873
·
IF 3.289
Yunfei Zhang,Bo Yang,Jinhong Fan,Luming Ma
In this study, abrasives-reinforced metal matrix composites (MMCs) with a microscale size synthesized by ball milling (BM) could achieve highly active and stable dechlorination efficiency for aqueous 2-chlorophenol (2-CP). The preparation process of this composite via BM was optimized to obtain a high degradation efficiency, especially for the effect of the abrasives including B4C, SiC, α-Al2O3, SiO2, Fe3O4 and Na2SO4. The results showed that the hardness of the abrasives in the Fe-based MMCs was closely related with their dechlorination performance. Subsequently, the optimal abrasive, i.e. SiO2 was further investigated for its proper milling conditions with zero-valent iron (ZVI) particles including optimal SiO2 size, SiO2 loading, milling time, and the dosage of the process control agent (PCA). Additionally, the influence of other metal categories including Al and Si was also investigated for dechlorination; and their low reaction efficiencies were closely related with their passivating film. Finally, the longevity test suggested that the decreased reactivity of the SiO2–Fe MMC during the storage in air could be recovered when consecutively used, mainly due to the promoting effects of the inherent structure of SiO2–Fe MMC with the Fe/C and Fe/SiO2 interfaces, as well as the effective regeneration of the reactive sites by continuous iron dissolution.
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
Journal of Environmental Chemical Engineering
·
2023
·
IF 7.7
Xiaoyan Ma,Sinong Huang,Yuhong Jin,Hang Jiang,Liangjie Tang,Yifei Wu,Yongjiong Ni,Shijun Zhu,Xueyan Li,Andrea M. Dietrich
Haloacetic acids (HAAs) are ubiquitously detected in drinking water and even persistent after boiling due to their stability and nonvolatility, which leads to risk exposure to human. To minimize the risk, HAAs removal through electrocatalytic reduction easily utilized in point-of-use household devices is proposed. Trichloroacetic acid (TCAA) as a typical target, was investigated using laboratory-prepared metal electrode modified with Vitamin B12 (VB12) by the drop coating method. The dechlorination performance and effects of influencing factors on the TCAA dechlorination by VB12/metal composite cathode were studied. Under the conditions of 10.0 mg VB12 loading and 7.0 mA/cm 2 current density, 92.9% TCAA removal efficiency was achieved within 5 h at 25 °C in neutral water solution. The degradation processes followed the first-order kinetic model. The results show that VB12/iron (Fe) electrode presented the superior electrocatalytic activity than VB12/aluminium and VB12/copper. The dechlorination efficiency of TCAA was promoted by higher VB12 loadings and current density; inhibited by alkaline condition and higher initial concentration of TCAA. The synergistic effect between atomic H* and VB12 occurred during the TCAA dechlorination process through the electron transfer . The proposed pathway elucidated that TCAA was dechlorinated to form dichloroacetic acid (DCAA) and monochloroacetic acid (MCAA), with acetic acid and chloride as ultimate products. This electrocatalysis system with VB12/Fe composite electrode exhibits high reaction efficiency, targeted dehalogenation, and environmental friendliness. This work is expected to provides a new way for the removal of halogenated DBPs at the tap and the safeguard drinking water for consumers.
研究领域:
环境科学
·
化学工程
·
水处理技术
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2019
·
IF 7.65
Dachao Ma,Qingge Feng,Boqing Chen,Xi Cheng,Kao Chen,Jiao Li
In order to reveal the chlorine behavior during hydrothermal carbonization (HTC) of medical waste, polyvinyl chloride and medical waste model (MW) were respectively treated by HTC at temperature ranging from 220 °C to 300 °C for 30 min. HTC products were characterized by Fourier Transform Infrared Spectrometer, X-ray Photoelectron Spectroscopy, etc. It is found that HTC can efficiently remove chlorine from both polyvinyl chloride and MW. The most dramatical dechlorination can be induced by HTC at around 240 °C. With HTC temperature increased, organic chlorine in HT-MW and solid product from polyvinyl chloride HTC (HT-PVC) is decreased. Interestingly, with 240 °C HTC, the organic chlorine of HT-MW was 15.30%, much lower than that of HT-PVC of 86.84%, indicating the cellulosic materials in MW can significantly boost the conversion of organic chlorine into inorganic form in HTC at 240 °C. While spherical particles assigned to HTC of cellulosic materials aggregate at the pores of polyvinyl chloride particle, trapping the release of chlorine into the liquid, consequently to lower dechlorination efficiency compared to that of polyvinyl chloride. Since the chlorine retain in the solid product was mainly in form of inorganic, further dechlorination is potential for MW by combining HTC with leaching/extracting.
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
CHEMOSPHERE
·
2023
·
IF 8.8
Jiaming Gan,Ting Zhu,Yizhan Zhang,Dailin Li,Ting Li,Min Zhao,ZengXia Zhao,Lei Wang
Since the coronavirus disease 2019 (COVID-19) pandemic epidemic, the excessive usage of chlorinated disinfectants raised the substantial risks of disinfection by-products (DBPs) exposure. While several technologies may remove the typical carcinogenic DBPs, trichloroacetic acid (TCAA), their application for continuous treatment is limited due to their complexity and expensive or hazardous inputs. In this study, degradation and dechlorination of TCAA induced by an in situ 222 nm KrCl* excimer radiation as well as role of oxygen in the reaction pathway were investigated. Quantum chemical calculation methods were used to help predict the reaction mechanism. Experimental results showed that UV irradiance increased with increasing input power and decreased when the input power exceeded 60 W. Decomposition and dechlorination were simultaneously achieved, where around 78% of TCAA (0.62 mM) can be eliminated and 78% dechlorination within 200 min. Dissolved oxygen showed little effect on the TCAA degradation but greatly boosted the dechlorination as it can additionally generate hydroxyl radical (•OH) in the reaction process. Computational results showed that under 222 nm irradiation, TCAA was excited from S 0 to S 1 state and then decayed by internal crossing process to T 1 state, and a reaction without potential energy barrier followed, resulting in the breaking of C–Cl bond and finally returning to S 0 state. Subsequent C–Cl bond cleavage occurred by a barrierless •OH insertion and HCl elimination (27.9 kcal/mol). Finally, the •OH attacked (14.6 kcal/mol) the intermediate byproducts, leading to complete dechlorination and decomposition. The KrCl* excimer radiation has obvious advantages in terms of energy efficiency compared to other competitive methods. These results provide insight into the mechanisms of TCAA dechlorination and decomposition under KrCl* excimer radiation, as well as important information for guiding research toward direct and indirect photolysis of halogenated DBPs.
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 RESEARCH
·
2022
·
IF 8.431
Chao Zou,Mansi Wang,Yixin Chen,Yu Qin,Yun Zhao,Liang Qiao,Shasha Zhu,Tianming Chen,Ye Yuan
Bioelectrochemical systems with biocathodes constitute a promising means to enhance the biological dechlorination of 2,4,6-trichlorophenol (2,4,6-TCP) in constructed wetland (CW) sediments. However, the effect of different cathodic potentials on the structure and function of 2,4,6-TCP-reducing biocathode communities in CW sediments is largely unknown. Here, we evaluated the performance and microbial community structure of 2,4,6-TCP-reducing biocathode systems at different cathodic potentials (− 0.5, − 0.7, − 0.9, and − 1.1 V vs. saturated calomel electrode). The dechlorination efficiency of 2,4,6-TCP with the biocathode relatively increased by 16.02%–33.17% compared to that in the open circuit. The highest 2,4,6-TCP dechlorination efficiency (92.34 ± 0.86%) was observed at − 0.7 V in sediment, which may be due to the highest abundance of functional genera (e.g., Pseudomonas , Spirochaeta ) at − 0.7 V. Metagenomic analysis provided new insights into the metabolic potential of microorganisms in CW sediments and suggested possible 2,4,6-TCP conversion pathways in sediments. 2,4,6-TCP was gradually dechlorinated to form 4-chlorophenol, followed by a ring-opening step via the activities of chlorophenol reductive dehalogenase and oxygenase (e.g., cprA , tfdB ). Interestingly, micro-electrical stimulation enhanced the expression of chlorophenol reductive dehalogenase ( cprA ). Therefore, our findings at the molecular and gene expression levels provide insights into the effects of different cathodic potentials on the performance and community structure of 2,4,6-TCP-reducing biocathode systems in CW sediments.
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
BIORESOURCE TECHNOLOGY
·
2018
·
IF 5.807
Linlin Chen,Junjie Shao,Hui Chen,Caiqin Wang,Xinyi Gao,Xiangyang Xu,Liang Zhu
For enhanced dechlorination of 2,4-dichloronitrobenzene (2,4-DClNB), a coupled microbial electrosynthesis-upflow anaerobic sludge reactor (MES-UASB) was established, and the effect of cathode potential on the performance of combined process was investigated in this study. Results showed that a higher dechlorination efficiency of 78.5 ± 6.1% was achieved in the coupled MES-UASB at −660 mV, and the degradation rate of 4-chloroaniline (4-ClAn) reached 4.61 mg·L −1 ·d −1 within 120 h at −660 mV of cathode potential in batch experiments. The results of Illumina sequencing indicated that the biocathode operated at a lower potential favored the enrichment of dechlorination-related microbes such as Dehalobacter , Dehalococcoides and Anaeromyxobacter both in granular sludge and cathode biofilm. It could be speculated that a lower cathode potential is more feasible for the dechlorination of 2,4-DClNB due to the enrichment of dechlorination-related microbes as well as the production of electrons with higher energy for long-distance electron transfer (LDET).
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
CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Yingxin Wu,Jingyan Zhou,Zhuohao Wu,Quanyun Ye,Wencheng Wu,Xiaowen Liu,Dechun He,Guifang Lv,Jie Zhang
The dechlorination of polychlorinated biphenyl (PCB) has been studied intensively, while the comprehensive understanding of the electron transfer and selectivity pattern mechanism is still limited. Therefore, in this study, the reactivity of nickel/zero-valent iron (Ni/Fe) was investigated during the dechlorination of 2,2′,4,4′,5-pentachlorobiphenyl (PCB-99) at various temperatures. Gas chromatography-mass spectrometry analysis and quantum chemical calculations, including bond dissociation energy, C-Cl bond length, and the lowest unoccupied molecular orbital (LUMO), were used to explore the dechlorination pathways and the electron selectivity. Results showed that the reduction efficiency of PCB-99 (100 μg L −1 ) did not increase monotonically with the temperature, but followed the order: 25 °C (75.9%) > 15 °C (62.5%) > 35 °C (51.6%), due to the thermodynamic evolution of Fe species to generate more Fe(II) and the abundance of oxygen vacancies at 25 °C. However, as the temperature continued raising to 35 °C, Ni/Fe was oxidized heavily and aggregated into large particles, significantly reducing the electron density of Fe(II) and inhibiting the electron transfer. The main dechlorination pathway was PCB-99 → PCB-47 → PCB-17 → PCB-8 → PCB-3 → biphenyl, indicating that electrons tended to attack C-Cl bonds following the order meta- > para- > ortho- position, which could be better explained by LUMO. Overall, this work is expected to improve the understanding of the dechlorination behavior of PCB-99 from both fundamental and applied perspectives.
研究领域:
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2015
·
IF 4.321
Chen Sun,Zimo Lou,Yu Liu,Ruiqi Fu,Xiaoxin Zhou,Zhen Zhang,Shams Ali Baig,Xinhua Xu
In this study, nanosized titanium nitride (nTiN) doped palladium/nickel (Pd/Ni) foam electrodes were prepared via electroless deposition method for the dechlorination of 2,4-dichlorophenoxyacetic acid (2,4-D). Characterization analyses including field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM) revealed that nTiN was successfully doped onto the electrode surface. 2,4-D was first dechlorinated to intermediate products p -chlorophenoxyacetic acid ( p -CPA) or o -chlorophenoxyacetic acid ( o -CPA) and then to the final product, phenoxyacetic acid (PA). The effects of environmental factors including initial 2,4-D concentration, current density, reaction temperature and dissolved anions were also studied. High initial 2,4-D concentration increased the efficient utilization of active hydrogen atom [H] by nTiN doped Pd/Ni foam electrodes. Increases in current density promoted better dechlorination efficiency while the hydrogen evolution side reaction was undesirably increased, leading to a lower average current efficiency. Higher reaction temperature was proved to be favorable for the enhancement of dechlorination efficiency. NO 3 − and reduced sulfur compounds including S 2− and SO 3 2− showed negative impacts on Pd catalytic capability, whereas CO 3 2− and Cl − exhibited less adverse effects on dechlorination efficiency. The activation energy ( E a) value of 2,4-D dechlorination by nTiN doped Pd/Ni foam electrode was calculated to be 32.06 kJ mol −1 . Two typical stages namely electrode activation and efficient dechlorination procedures occurred in 2,4-D dechlorination by nTiN doped Pd/Ni foam electrodes. The reaction paths of [H] on the electrode were also summarized. The removal efficiency of 2,4-D dechlorination on nTiN doped Pd/Ni foam electrodes was observed to slightly decrease from 100% to 89.95% after 5 consecutive experiments.
研究领域:
环境科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
Computational Intelligence and Neuroscience
·
2022
·
IF 3.12
Jianghua Peng,Houzhang Tan
This exploration intends to remove chloride ions in production and life, enhance buildings’ durability, and protect the natural environment from pollution. The current dechlorination technology is discussed based on the relevant theories, such as the lightweight deep learning (DL) model and chloride ion characteristics. Next, data statistics and comparative analysis methods are used to study the adsorption and desorption performance of dechlorination adsorbents. Finally, the lightweight DL model is introduced into the chloride diffusion prediction experiment of slag powder and fly ash concrete. The results show that in the study of dechlorination adsorption performance, the chloride ion concentration decreases gradually with the extension of adsorption time. However, with the increasing temperature, the chloride ion removal rate is increasing. The removal rate of chloride ions in water can decrease slowly with the increase of adsorbent. Therefore, selecting the 2 mol/L sodium hydroxide as the alkali concentration for adsorbent regeneration is the most appropriate. Besides, the regeneration performance of the adsorbent gradually declines with the increase of sodium chloride concentration in the solution. The lightweight DL model is applied to the chloride diffusion prediction experiment of slag powder and fly ash concrete. It is found that when the curing age is selected at 18 days, 90 days, and 180 days, respectively, the error between the lightweight DL model and the experimental results is about 0.2. It shows that the lightweight DL model is feasible for predicting the diffusion of chloride ions. Therefore, this exploration designs and studies the dechlorination experiment based on the lightweight DL model, which provides a new theoretical basis and optimization direction for removing chloride ions in the future industry.
研究领域:
材料科学
·
环境工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）