ENVIRONMENTAL RESEARCH
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2024
·
IF 7.7
Bing Li,Weiquan Li,Qian Zuo,Weizhao Yin,Ping Li,Jinhua Wu
A weak electric field (WEF, 2 mA cm −2 ) was employed to promote Fe(III)/Fe(II) cycle on goethite-impregnated activated carbon (FeOOH@AC) filled in a continuous-flow column for enhanced Cr(VI) elimination from water. Surficial analysis and Cr species distribution showed that α-FeOOH of 0.2–1 μm was successfully synthesized and evenly loaded onto AC. Electron transfer from WEF to α-FeOOH was facilitated with AC as electron shuttles, thereby boosting Fe(III) reduction in the α-FeOOH. The generated Fe(II) reduced Cr(VI) and the resultant Cr(III) subsequently precipitated with OH − and Fe(III) to form Cr(OH) 3 and (Cr χ Fe 1-χ )(OH) 3 . Therefore, the WEF-FeOOH@AC column exhibited a much lower Cr(VI) migration rate of 0.0018 cm PV −1 in comparison with 0.0037 cm PV −1 of the FeOOH@AC column, equal to 104 % higher Cr(VI) elimination capacity and 90 % longer column service life-span. Additionally, under different Cr(VI) loadings by varying either seepage velocities or influent Cr(VI) concentrations, the WEF-FeOOH@AC column maintained 1.0–1.5 folds higher Cr(VI) elimination and 0.9–1.4 folds longer longevity than those of the FeOOH@AC column owing to the interaction between FeOOH@AC and WEF. Our research demonstrated that WEF-FeOOH@AC was a potential method to promote Cr(VI) elimination from water and offer an effective strategy to facilitate Fe(III)/Fe(II) cycle in iron oxides .
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JOURNAL OF ENVIRONMENTAL MANAGEMENT
·
2025
·
IF 8.4
Yuliang Tu,Jianle Wang,Yanfeng Huang,Hong Deng,Xueming Liu,Jiaxin Lv
Hexavalent chromium [Cr(VI)] presents substantial environmental and health hazards due to its pronounced toxicity and mobility in soils. Traditional chemical reduction methods for Cr(VI) are often inadequate for treating chromium-contaminated soils, as they may fail to fully reduce Cr(VI), leading to incomplete remediation. Consequently, there is a critical need to develop more efficient and environmentally sustainable methods for the treatment of hexavalent chromium. This study explores an innovative approach using microwave-enhanced reduction of soil iron minerals facilitated by tea polyphenols to achieve transformational fixation of Cr(VI). The microwave-assisted treatment (0.5 wt% TP combined with MW at 700 W for 10 min) significantly reduced Cr(VI) concentrations in iron-rich soil from 363.4 mg kg −1 to 0.3 mg kg −1 , achieving a removal rate of 99.9%, compared to TP treatment alone (0.5 wt%). Transmission electron microscopy (TEM), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) analyses revealed that the enhanced removal efficiency of Cr(VI) by microwave-assisted tea polyphenols is attributable to the accelerated reduction of soil iron minerals by the polyphenols. Furthermore, microwave enhancement facilitated the transformation of Cr into more stable forms, such as Cr 2 O 3 and FeCr 2 O 4 . Additionally, the Cr(VI) content in the treated soil remained below 3 mg kg −1 after 360 days of atmospheric exposure, indicating sustained immobilization. This study demonstrates that the integration of tea polyphenols with microwave irradiation constitutes a promising strategy for the remediation of Cr(VI)-contaminated soils.
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APPLIED SURFACE SCIENCE
·
2025
·
IF 6.9
Mimi Sun,Jiahui He,Wanting Xiang,Wei Zou,Wenfei Song,Yating Xi,Jun Yan,Meimei Zhou,Pingping Luo
The design and construction of diverse heterojunction architectures have emerged as an effective strategy for enhancing the photocatalytic performance of semiconductors. In this study, ZIF-8/TiO 2 composite nanofibers were successfully fabricated by combining electrospinning technology with a facile in-situ solvothermal method, followed by ZIF-8 sulfurization to form ZnS/TiO 2 nanofiber heterostructures. Comprehensive characterization confirmed that ZIF-8 on the surface of TiO 2 nanofibers was completely converted into ZnS, establishing a robust and intimate interface with TiO 2 . The resulting ZnS/TiO 2 heterojunction exhibited remarkable photocatalytic reduction activity for Cr(VI), achieving 100% removal efficiency within 20 min under visible light irradiation. The photocatalytic reaction rate constant of the ZnS@TiO 2 nanofibers was approximately 10 and 319.5 times higher than those of pristine ZnS and TiO 2 nanofibers, respectively. This enhanced photocatalytic performance is attributed to the formation of the heterojunction, which effectively narrows the bandgap of the composite, optimizes photogenerated charge transfer pathways and significantly improves electron-hole pairs separation. Furthermore, mechanistic studies identified photogenerated electrons (e − ) and superoxide radicals ( O 2 − ) as the dominant active species involved in the photocatalytic reduction process. This work provides both fundamental understanding and practical methodology for developing high-performance TiO 2 -based photocatalytic systems, highlighting their potential for advanced water purification technologies.
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Desalination and Water Treatment
·
2024
·
IF 1
Jing Yang,Siyuan Yang,Jing Zhang,Jian He,Wei Jiang
ABSTRACT The recovery of Cr(VI) from the solution and the utilization of by-products are significant for waste-water treatment and environmental protection. In this study, the amorphous ZrO 2 was prepared using a solvothermal method and used to treat the wastewater containing Cr(VI). Amorphous ZrO 2 is effective for the photocatalytic reduction of Cr(VI). Without a sacrificial agent, 20 mL potassium dichromate solution (20 mg/L) is reduced to almost 0 mg/L within 10 min. Moreover, the by-products obtained from this process exhibit good performance in the catalytic dehydrogenation of ethane coupled with the reverse water–gas reaction. The maximum yield of ethylene is 12.9%, and the service life of the catalyst reached 160 min. Catalyst deactivation is caused by carbon deposition, and the deactivated catalyst is regenerated by roasting in the air. The feasibility of this green process is demonstrated, including the one-step photocatalytic reduction of Cr(VI) and utilization of the by-product as an ethane dehydrogenation catalyst.
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JOURNAL OF HAZARDOUS MATERIALS
·
2022
·
IF 14.224
Xiaofeng Yi,Shurui Liu,Mingyu Luo,Qingbiao Li,Yuanpeng Wang
Microbe-photocatalyst biohybrids, integrating the optimal attributes of whole-cell catalysts and nanometer photocatalysts, have emerged as a promising strategy for environment-associated applications. However, few such biohybrids have been tested for complex pollution systems. Herein, we constructed an outer membrane photosensitized Geobacter sulfurreducens ( G. sulfurreducens )-CdS biohybrid, which enabled to generate stronger photocurrent in response to irradiation and meanwhile achieved an significant promotion for the redox transformation of Cr(VI) and tetracycline compared with that of bare G. sulfurreducens or CdS counterparts. Further analysis revealed that the outer membrane played a significant role in photoelectron transfer. Differential pulse voltammetry (DPV) tests demonstrated that CdS enhanced the catalytic activity of C-type cytochromes on the outer membrane under irradiation, resulting in the increase of electron-hole pairs separation efficiency. The possible degradation pathway of tetracycline was proposed based on determined intermediates, whose toxicities were well evaluated. Importantly, the toxicity of the final detected intermediates was apparently decreased. Overall, this work aims to explore the working mechanisms of the novel G. sulfurreducens -CdS biohybrid system and opens up a new avenue to purifying combined wastewater by microbe-photocatalyst biohybrids.
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JOURNAL OF THE ELECTROCHEMICAL SOCIETY
·
2018
·Vol. 165
·期 16
·B893
·
IF 3.662
Jingfang Hu,Ye Liu,Guowei Gao,Xiaoping Zou
One-step electrochemical approach for synthesis of AuPdNPs/ERGO nanocomposite has been developed for Cr(VI) sensing in water. The bimetallic AuPd nanoparticles and electrochemical reduced graphene oxide (ERGO) composite (AuPdNPs/ERGO) were reduced from H2PdCl4, HAuCl4 and GO mixed solution and deposited onto glass carbon electrode (GCE) through cyclic voltammetry, simultaneously. The bimetallic AuPdNPs were homogeneously modified on graphene nanosheets and characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX) technique. Based on the voltammetric results, the bimetallic AuPdNPs/ERGO/GCE had higher catalytic activity for Cr(VI) determination, compared with AuNPs/GCE, PdNPs/GCE and ERGO/GCE obtained by the same method. The fabricated AuPdNPs/ERGO/GCE shows good relationship in two concentration ranges from 0.05 μM to 5 μM and 5 μM to 1000 μM, with a detection of 0.013 μM (at S/N = 3). In addition, the proposed modified electrode presents high selectivity, sensitivity and stability for Cr(VI) detection and a high recovery of more than 95% was obtained towards real water application, which makes it favorable for the further practical field monitoring.
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ACS ES&T Engineering
·
2022
·
IF 0
Ting Zhang,Zhelun Pan,Dinggui Song,Hong Huang,Jiang Yu,Yichan Wen,Junlin Lu,Zhenfeng Bian,Xufang Qian
The high reactivity of Fe(0) with Cr(VI) makes it the best choice for Cr(VI) removal. Interstitial compound Fe3C was produced during the carbothermic reduction of mesoporous phenolic resin/ferric ions to form Fe(0)/Fe3C nanoparticles embedded in mesoporous carbon (Fe(0)/Fe3C@MesoC). Fe3C accelerates the electrochemical corrosion process of α-Fe(0) in solution, and the positive/negative equipotential interface that is formed by iron–carbon (Fe–C) microelectrolysis of Fe(0)/Fe3C@MesoC induces the capture of Cr(VI) anions and Cr(III) cations as a result of this process. Cr(VI) was completely reduced to Cr(III) by the Fe(0)/Fe3C@MesoC catalyst with a high electron efficiency (40.5%) relative to nanosized zero-valent iron (1.9%) and Fe@MesoC (32.7%). Surface ferrous ions are the principal reactive species responsible for Cr(VI) reduction (at least 64%); Fe(0)/Fe3C and undetectable surface ferrous ions account for a small part of Cr(VI) reduction (around 28%), and only 8% of Cr(VI) ions are reduced by active hydrogen (H*). The proposed structure of Fe(0)/Fe3C@MesoC provides new insight into iron–carbon material preparation and application in in situ chemical reduction.
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SCIENCE OF THE TOTAL ENVIRONMENT
·
2024
·
IF 8.2
Huirong Zhang,Yi Shen,Xiaokai Shi,Jinlei Cui,Baofeng Wang,Yanxia Guo,Dongke Zhang,Fangqin Cheng
Persistent environmental pollution by heavy metals, particularly Cr (VI), poses significant risks to ecosystems and human health due to its high toxicity and bioaccumulation potential. The development of high-performance, cost-effective adsorbents from sustainable materials remains a critical challenge in the field of Cr (VI) remediation. This study investigates the influence of pyrrolic-N (N-5) within nitrogen-doped hierarchical porous carbon (N-HPC) on its adsorption capacity. Results indicate that N-HPC variants with a higher N-5 content exhibit superior adsorption abilities. The optimal sample demonstrated an exceptional adsorption capacity of 386.2 mg/g for Cr (VI). Even after seven regeneration cycles, this N-HPC variant maintained a remarkable 77.8 % removal efficiency for Cr (VI), highlighting its robust stability and selectivity. The relationship between the physicochemical properties of N-5 and N-HPC was thoroughly examined, revealing that N-5 plays a crucial role in the adsorption process. Due to its high electronegativity, nitrogen-doping into the carbon framework generates a dipole moment, enhancing the electronegativity of N-HPC, altering its local electron density and polarity, increasing specific surface area, carbon defect density, and ion exchange capacity. These factors collectively contribute to significant improvements in pore filling, ion exchange efficiency, and electrostatic adsorption by N-HPC. The reduction complexation mechanism emerges as the dominant factor in the adsorption process. N-5 not only provides reducing electrons as an electron donor, facilitating the continuous conversion of Cr (VI) to Cr (III), but also acts as an adsorption active site, complexing Cr to the surface of N-HPC. This synergistic effect strengthens the reduction complexation, enhances adsorption performance, and improves the regeneration cycle and adsorption selectivity for Cr.
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ENVIRONMENTAL RESEARCH
·
2025
·
IF 7.7
Xiao-Qian Jin,Jia-Lei Li,Jun-Bin Xiong,Rui Zhang,Chen-Yuan Li,Xue-Ting Wang,Wei-Hong Guo,Da-Chuan Yin
In this work, cross-linked hemoglobin crystals (CLHCs) were synthesized using discarded cow blood as raw material, and palladium nano particles (Pd NPs) was synthesized in situ within its lattice to obtain CLHCs@Pd catalytic used for catalyzing the reduction of Cr(VI). In addition, we investigated the influence of synthesis process on the morphology, loading capacity, and size of Pd NPs, and the results showed that the minimum size of Pd NPs was distributed around 2 nm under any process conditions. The X-ray single crystal diffraction results indicate that the lattice of protein crystals may have a controlling effect on the size of Pd NPs. Subsequently, the mechanism of synthesizing Pd NPs by CLHCs was studied using techniques such as SEM, TEM, FTIR and XPS. Finally, the catalytic activity and cycling performance of Cr(VI) removal by CLHCs@Pd were evaluated. The results indicate that the CLHCs@Pd not only exhibit high catalytic activity for Cr(VI) removal, but also maintain consistent catalytic performance over 20 consecutive catalytic cycles. Overall, this work provides CLHCs@Pd catalysts have the following advantages: (1) small size and uniform dispersion of Pd NPs; (2) High cycling performance and high catalytic activity; (3) Low cost and environmentally friendly preparation process.
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Frontiers of Chemical Science and Engineering
·
2021
·Vol. 15
·期 5
·1185-1196
·
IF 4.204
Liu Wanyue,Liu Xiaoqin,Chang Jinming,Jiang Feng,Pang Shishi,Gao Hejun,Liao Yunwen,Yu Sheng
The magnetic nitrogen-doped carbon (MNC) was prepared from polypyrrole by a simple high temperature calcination process in this paper. The structure and properties of MNC were analyzed by scanning electron microscope, Fourier transform infrared spectroscopy, X-ray diffraction, Brunner-Emmet-Teller, vibrating sample magnetometer, and X-ray photoelectron spectroscopy. The capacity of MNC to adsorb Cr(VI) and Pb(II) was evaluated. The effects of the initial pH, dosage, concentration and temperature on the adsorption capacity of MNC were measured. MNC had a large specific surface area and a special porous structure. Its nitrogen and carbon sources were rich, and the ratio of carbon to nitrogen was fixed. The maximum Cr(VI)-adsorption capacity and maximum Pb(II) adsorption capacity of MNC could reach 456.63 and 507.13 mg·g −1 at 318 K, respectively. The pseudo-second-order model was used to describe the adsorption kinetics of MNC, and the Freundlich model was employed to discuss its isotherms. The adsorption process was affected by the electrostatic force, the reducing reaction, pores and chelation. The results of this study suggest that MNC is a material with superior performance, and is very easily regenerated, reused, and separated in the adsorption process.
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CATALYSIS TODAY
·
2013
·
IF 2.98
Xuefeng Hu,Huanhuan Ji,Fei Chang,Yongming Luo
In this study, a rapid reduction of Cr(VI) and degradation of 2,4,6-trichlorophenol (2,4,6-TCP) in a simultaneous manner was reported through the catalysis of g-C 3 N 4 under visible light ( λ > 420 nm) irradiation. The effects of initial concentration of reactants, dissolved O 2 and pH value were investigated systematically. It indicated that, under the optimized concentration, the Cr(VI) reduction and 2,4,6-TCP oxidation could be accomplished in couple of hours in the presence of g-C 3 N 4 . And also, the O 2 involvement and low pH value were able to significantly improve the removal rate of Cr(VI) and 2,4,6-TCP. In addition, the reaction mechanism was investigated through monitoring the reduced states of Cr(VI) and active oxygen intermediates formed during photoreaction by ESR and XPS, as well as determining the degradation products of 2,4,6-TCP by HPLC–MS. The results supported that the redox reactions of Cr(VI) and 2,4,6-TCP can be performed simultaneously via a synergistic oxidation–reduction mechanism in the presence of g-C 3 N 4 under visible light irradiation.
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CHEMOSPHERE
·
2018
·
IF 4.427
Peng Liu,Xiangyu Wang,Jun Ma,Huiling Liu,Ping Ning
To provide superior substrates and determine the specific species of immobilized nano zero-valent iron (NZVI) system, polyacrylonitrile (PAN) membrane was functionalized by bio-inspired polydopamine (PDA) and poly( l -DOPA) (PDOPA) for efficient immobilization of NZVI. The synthesized composites were denoted as PAN/PDA-NZVI (PPN) and PAN/PDOPA-NZVI (PON), respectively. Analyses of XRD, SEM/EDS and XPS show that the aggregation and release of iron nanoparticles had been successfully controlled by improving membrane hydrophilcity and iron-chelating capacity via the graft of functionalized groups (i.e. OH and COOH) of PDA and PDOPA on PAN membrane. Both PPN and PON composites exhibited superior reactivity for Cr(VI) removal (Cr(VI) removal efficiency and reaction rate were 2.21–2.22 and 9.90–10.14 times higher than that of bare NZVI, respectively). The stability and recyclability of PPN and PON composites could be maintained over repeated cycles. Further analyses indicate that PON is more capable for Cr(VI) elimination than PPN due to the proprietary carboxyl of l -DOPA. With the addition of 1,10-phenanthroline, membrane-chelated Fe(II) was determined to be the major species in Cr(VI) removal system, accounting for 56.9% and 53.8% with regard to PPN and PON composites, and Fe 0 was responsible for the reduction of residual Cr(VI). Analyse of reacted composites revealed that Cr(VI) was completely converted into Cr(III), followed by formation of dominant Cr(III)/Fe(III) (oxy)hydroxides and partial desorption from NZVI reactive sites. This study suggested that both synthesized PPN and PON composites have potentials for Cr(VI)-contaminated wastewater treatment .
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