CHEMOSPHERE
·
2016
·
IF 3.698
Wenjuan Fan,Junlian Qiao,Xiaohong Guan
A new method for Cr(VI) (0.025–8.00 mg/L) determination based on the reaction of Cr(VI) and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) in aqueous solutions was developed. The colorless ABTS reacted with Cr(VI) under strong acidic conditions ([H + ] = 3.0 or 6.0 M) producing a stable colored radical ABTS + , which could be measured spectrophotometrically at 415, 649 or 732 nm. The absorbance increase at these three wavelengths for ABTS + generation were all linear (less than 1.0% deviation) with respect to the amount of added Cr(VI) and the sensitivity were 1.099 × 10 5 , 3.720 × 10 4 , and 4.150 × 10 4 M −1 cm −1 of added Cr(VI) at 415, 649 or 732 nm, respectively. Cr(VI) of 0.025 mg/L below the discharge standard of drinking water could be detected with the method quantitatively and 0.002 mg/L Cr(VI) was determined qualitatively. The molar absorptivity of ABTS + generated was determined to be (3.69 ± 0.01) × 10 4 M −1 cm −1 at 415 nm and the reaction between Cr(VI) and ABTS had a stoichiometric factor of 1:3 in excess of ABTS. The absorbance of generated ABTS + was found to be stable in deionized water or wastewater and Cr(VI) spiked in wastewater could be determined accurately. The ABTS method also had a good anti-interference performance against Co(II) ions. Moreover, the ABTS method could be successfully used in the Cr(VI)-S(IV) system for Cr(VI) determination.
研究领域:
分析化学
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环境科学
✓ 已验证
DOI
高影响因子
JOURNAL OF MOLECULAR LIQUIDS
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2022
·
IF 6.633
Min Xu,Xiaoli Ma,Yahui Chen,Luzeng Hu,Bo Wang,Muqing Qiu
Nanoscale zero-valent iron/biochar (nZVI/biochar) has been widely utilized in environmental remediation due to its excellent removal efficiency, easy synthesis, low-cost and environmental friendliness. Herein, the removal and interaction mechanism of Cr(VI) removal on nZVI/biochar was investigated by macroscopic and microscopic techniques. Compared to nZVI (25.84 mg/g), the high removal capacity (63.29 mg/g at pH 4.5), excellent reusability and chemical stability of nZVI/biochar were due to various oxygen-bearing functional groups and synergetic interaction. According to analysis of X-ray photoelectron spectroscopy (XPS), X-ray absorption near-edge fine (XANES) and extended X-ray absorption fine structure (EXAFS) spectra, the interaction mechanism of Cr(VI) on nZVI/biochar followed adsorption (complexation, electrostatic interaction), reduction and co-precipitation process with increasing reaction time. These findings are crucial for the application of nZVI/biochar for removal of heavy metals in actual environmental cleanup.
研究领域:
环境科学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
Environmental Science-Nano
·
2024
·
IF 5.8
Chaorong Chen,Haiyang Xian,Jing Liu,Qingze Chen,Xiaoliang Liang,Runliang Zhu,Michael F. Hochella
Photochemical and adsorptive reactions occurring at the mineral–water interface are of great importance in controlling the fate and transport of contaminants in nature, but the effects of the mineral surface structure on the interplay of these two processes and the underlying mechanisms remain largely unknown. In this work, two different structurally well-defined hematite nanocrystals were employed to explore the coupled photoreduction and immobilization of Cr(VI) on various facets of hematite under light irradiation. Compared with hematite quasi-nanocubes (HNCs) exposing only {012} facets, hematite nanoplates (HNPs) with exposed {001} and {113} facets exhibited higher immobilization ability for Cr(VI) under light irradiation, indicating that the coupled process of photoreduction and adsorption of Cr(VI) strongly relied on the particularly exposed facets of hematite. X-ray photoelectron spectroscopy measurements indicated that the removed Cr(VI) from solution was mainly immobilized on hematite surfaces in the form of Cr(III) (the reduced products of Cr(VI)). Transmission electron microscopy and electron energy-loss spectroscopy results revealed that the accumulation of Cr species was predominantly on the {113} facets of HNPs and the {012} facets of HNCs. Theoretical calculations show that the work function difference between the {113} and {001} facets was directly linked with the effective separation of photogenerated electron–hole pairs in HNPs, which is beneficial for the reduction of Cr(VI). The results of desorption experiments indicate that the coupling of photoreduction and adsorption processes significantly promotes the long-term immobilization of Cr species and effectively reduces their environmental risks (the desorption of Cr(VI) from the HNP and HNC samples decreased from 35.9% and 33.5% to 0.3% and 1.7%, respectively). Overall, the exposed facets can significantly affect the electron transfer properties of hematite as well as the binding affinity for Cr species, thereby governing the reduction and immobilization behavior of Cr(VI) on various facets of hematite. These results advance our understanding of the speciation and immobilization of redox-sensitive contaminants at the surfaces of semiconducting minerals in nature.
研究领域:
环境科学
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表面化学
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产品关联
DOI
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2018
·Vol. 42
·期 11
·9006-9015
·
IF 3.201
Huating Sun,Tianxing Wu,Yunxia Zhang,Dickon H. L. Ng,Guozhong Wang
Molybdenum disulfide (MoS2) was successfully synthesized via a facile one-step hydrothermal method without addition of templates or surfactants. The obtained MoS2 product was characterized via various techniques including FESEM, HRTEM, XRD, BET and XPS analyses. Their application in capturing Cr(VI) ions in water was investigated. The results showed that the MoS2 nanosheets were ultrathin with a thickness of 5–10 nm and had a uniform lateral size of 100–200 nm. Impressively, these MoS2 nanosheets not only possessed enlarged interlayer spacing, but also had multiple defects on the basal planes, which were proved to be crucial in the removal of Cr(VI). The kinetics of chromium adsorption was found to follow the pseudo-second-order rate equation and the adsorption isotherm data were well fitted to the Langmuir model with a chromium in-take capacity of about 84.03 mg g−1. This structure-enhanced removal was likely related to the synergism of adsorption and reduction, in which the anionic Cr(VI) was adsorbed on the surface of D-MoS2via electrostatic interaction. At the same time, some fraction of the adsorbed Cr(VI) was reduced to low toxic Cr(III) and the generated Cr(III) species were adsorbed by the adsorbent. More significantly, the adsorption and reduction processes not only transferred the Cr(VI) from the aqueous environment to the surface of solid adsorbents but also alleviated the toxicity of Cr(VI). It was evident that this study may promote the application of other transition metal dichalcogenides in environmental remediation.
研究领域:
环境科学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
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2022
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IF 14.224
Zhiyan Yan,Chenrui Liu,Yun Liu,Xiaoqian Tan,Xinyue Li,Yan Shi,Chunlian Ding
Cr(VI) contaminated water usually contains other contaminants like engineered nanomaterials (ENMs). During the process of microbial treatment , the inevitable interaction of Cr(VI), ENMs, and microorganisms probably determines the efficiency of Cr(VI) biotransformation , however, the corresponding information remains elusive. This study investigated the interaction of ZnO nanoparticles (NPs), Cr(VI), and Pannonibacter phragmitetu s BB (hereafter BB), which changed the process of microbial Cr(VI) reduction. ZnO NPs inhibited Cr(VI) reduction, but had no effect on bacterial viability. In particular, Cr(VI) induced BB to produce organic acids and to drive Zn 2+ dissolution from ZnO NPs inside and outside of cells. The dissolved Zn 2+ not only promoted Cr(VI) reduction to Cr(V)/Cr(IV) by strengthening sugar metabolism and inducing increase in NAD(P)H production, but also hindered Cr(V)/Cr(IV) transformation to Cr(III) through down-regulating Cr(VI) reductase genes. A novel bacterial driven ROS scavenging mechanism leading to the inhibition of Cr(VI) reduction was elucidated. Specifically, the accumulated Cr(VI) and Cr(V)/Cr(IV) formed a redox dynamic equilibrium, which triggered the disproportionation of superoxide radicals mimicking superoxide dismutase through the flip-flop of Cr(VI) and Cr(V)/Cr(IV) in bacterial cells. This study provided a realistic insight into design the applicability of biological remediation technology for Cr(VI) contaminant and evaluating environmental risks of ENMs.
研究领域:
环境科学
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微生物学
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纳米技术
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生物修复
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Materials
·
2022
·Vol. 15
·期 11
·3761
·
IF 3.748
Lei Wu,Doudou Qin,Fan Fang,Weifeng Wang,Wenying Zhao
Severe environmental pollution is caused by the massive discharge of complex industrial wastewater. The photocatalytic technology has been proved as an effective way to solve the problem, while an efficient photocatalyst is the most critical factor. Herein, a new photocatalyst MIL-68(Ga)_NH2was obtained by hydrothermal synthesis and were characterized by PXRD, FTIR,1H NMR, and TGA systematically. The result demonstrates that MIL-68(Ga)_NH2crystallized in orthorhombic system andCmcmspace group with the unit cell parameters:a= 36.699 Å,b= 21.223 Å,c= 6.75 Å,V= 5257.6 Å3, which sheds light on the maintenance of the crystal structure of the prototype material after amino modification. The conversion of Cr(VI) and binary pollutant Cr(VI)/RhB in wastewater under visible light stimulation was characterized by the UV-vis DRS. Complementary experimental results indicate that MIL-68(Ga)_NH2exhibits remarkable photocatalytic activity for Cr(VI) and the degradation rate reaches as high as 98.5% when pH = 2 and ethanol as hole-trapping agent under visible light irradiation with good reusability and stability. Owing to the synergistic effect between Cr(VI) and RhB in the binary pollutant system, MIL-68(Ga)_NH2exhibits excellent catalytic activity for both the pollutants, the degradation efficiency of Cr(VI) and RhB was up to 95.7% and 94.6% under visible light irradiation for 120 min, respectively. The possible removal mechanism of Cr(VI)/RhB based on MIL-68(Ga)_NH2was explored. In addition, Ga-based MOF was applied in the field of photocatalytic treatment of wastewater for the first time, which broadened the application of MOF materials in the field of photocatalysis.
研究领域:
环境科学
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材料科学
✓ 已验证
DOI
高影响因子
JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY
·
2023
·
IF 6.1
Nian Liu,Yuqi Zhang,Jiaoyan Huang,Sicong Liu,Taiping Qing,Peng Zhang,Bo Feng
In the realm of sensing, carbon dots (CDs) have exhibited remarkable fluorescence characteristics. In the field of catalysis, CDs can function concurrently as electron donors and acceptors and have substantial electron or hole transport capacities. In this study, both merits were integrated into one, and a one-step hydrothermal approach was used to create multifunctional CDs. On the one hand, CDs are employed as a fluorescence probe with good sensitivity and selectivity to detect Cr(VI). On the other hand, CDs exhibit strong photoreduction capabilities for Cr(VI) in the absence of any external cocatalysts or photosensitizers when acting as photoinitiators. The results show that Cr(VI) quenches the CDs fluorescence as a result of the combined effects of static quenching and the inner filter effect. At the same time, under the condition of illumination, the inner filter effect encourages the CDs electrons to move from the valence band to the conduction band, resulting in electron hole pairs. With the help of electrons' reducing power, Cr(VI) can be rapidly and effectively converted to Cr(III). The findings of this study suggest that CDs are a satisfying bi-functional carbon-based material with significant potential for the treatment of industrial wastewater.
研究领域:
环境科学
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材料科学
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产品关联
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
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2022
·
IF 5.518
Qiang Li,Hao Zhou,Meng Tan,Lingxuan Yang,Xiao Hu,Guoxiang Yang,Hao Du,Qing Wei,Qi Wang
High visible light utilization and rapid charge separation are of great importance for environmental photocatalysis . Single photocatalyst always suffers from high recombination of photogenerated electron-hole pairs and low redox ability. Elemental doping and heterojunction construction are effective approaches to improve the photocatalytic performance. Herein, we designed and synthesized a novel Bi x Fe y VO 4 /g-C 3 N 4 (BFC) binary heterojunction via facile coprecipitation followed by calcination processes. The doping of Fe endows BiVO 4 with narrower bandgap, which boosts its light response and redox ability. The construction of heterojunction facilitates charge separation that makes BFC heterojunction displaying much higher photocatalytic activity than those of single semiconductors. The highest Cr(VI) photoreduction rate ( k ) of BFC binary heterojunction is 78 (45) times of BiVO 4 (FeVO 4 ). Additionally, the binary heterojunction can still maintain high photoreduction efficiency (98%) of Cr(VI) even after five cycling tests showing excellent photocatalytic stability. This research provides novel idea for synergistic application of doping and heterojunction in environmental photocatalysis.
研究领域:
环境科学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
Environmental Science-Nano
·
2024
·
IF 5.8
Shengnan Zhang,Lingyi Li,Junxue Li,Wei Cheng
Hematite displays diverse crystal structures and often coexists with Fe(II), both of which are crucial in controlling the fate and mobility of Cr(VI). However, the mechanisms underlying Cr(VI) removal in the presence of Fe(II) on various hematite facets remain elusive. This study aims to elucidate the facet-dependent reactivity of hematite nanocrystals in conjunction with Fe(II) for the removal of Cr(VI) from aqueous solutions. Hematite nanoplates (HNPs), predominantly composed of {001} facets, and nanorods (HNRs), exposing both {001} and {110} facets, were synthesized and characterized. Their Cr(VI) removal capabilities were evaluated in hematite–Cr(VI) and hematite–Fe(II)–Cr(VI) systems, as well as the Fe(II)–Cr(VI) system. The adsorption of Fe(II) and Cr(VI) on hematite surfaces was highly dependent on the crystal facets and pH, with HNRs demonstrating superior Cr(VI) adsorption over HNPs, especially under acidic conditions. Neutral pH favored Fe(II)–Cr(VI) redox reactions and Fe(II) adsorption. The hematite–Fe(II) couple displayed a synergistic effect in removing Cr(VI) under acidic conditions, which was not observed under neutral conditions. The presence of Fe(II) notably enhanced Cr(VI) adsorption onto hematite, and bound Fe(II) facilitated electron transfer, accelerating Cr(VI) reduction. HNRs–Fe(II) exhibited higher Cr(VI) removal efficiency than HNPs–Fe(II) due to their lower free corrosion potential and improved electron transport properties. This research underscores the potential of facet engineering in optimizing hematite nanocrystals for environmental remediation, specifically in Cr(VI)-contaminated environments.
研究领域:
环境科学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMOSPHERE
·
2022
·
IF 8.943
Xiaofeng Jiang,Wenjun Long,Liangqiong Peng,Teng Xu,Faming He,Yuling Tang,Wenhua Zhang
The rapid reductive immobilization of Cr(VI) from the aqueous solution was achieved by reduction to Cr(III) using tannic acid (TA), and subsequent pH-triggering precipitation of the organo-Cr(III) complexes formed in the redox reaction. The effects of TA concentration, temperature, and solution pH on the reduction of Cr(VI) were examined by batch experiments, and the rapid redox reduction followed a second-order kinetics with respect to Cr(VI) concentration in the pH range of 2.0–3.0. UV–visible spectra, FTIR, and XPS confirmed the complete detoxification of Cr(VI) concomitant with carboxylation of partial phenolic hydroxyls in TA. Synchronously, the reduced Cr(III) coordinated with carboxyl groups in oxidized TA (OTA) to form complexes, which exhibited remarkable pH-dependent size distribution characteristics as illustrated by SEM images and sequential filtration/ultrafiltration. The resulted Cr(III) complexes could aggregate into colloids with larger size and precipitate out at pH range of 6.0–8.0 via cross-linking, thereby leading to 93% Cr and 89% TOC immobilization. An eco-friendly and cost-effective method for Cr(VI) elimination and immobilization is provided because polyphenols are natural polymers derived from plants.
研究领域:
环境科学
·
化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
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.
研究领域:
材料科学
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环境科学
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产品关联
DOI
高影响因子
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2019
·Vol. 27
·期 15
·17446-17457
·
IF 2.914
Gao Zhao,Yang Hanpei,Fu Xiaofei,Jin Qiu,Wu Qiangshun,Kang Li,Wu Junming
Slow and random transfer of pollutants and photo-induced carriers on photocatalysts causes loss of efficiency in photodegradation of contaminants. Enhancing and directing mass transfer of them are considered as two major methods for improving the photodegradation of pollutants over photocatalysts. Here in this work, we focused on the design of a novel photocatalyst which not only accelerated the transfer rate of Cr(VI) and electrons but also provided specific transfer routes for them. By careful characterizations, it is indicated that 2-((2-(2-aminoethylamino)ethylimino)methyl)phenol (AEMP) was covalently attached onto activated carbon (AC), which enhanced Cr(VI) transfer from bulk solution to AC through electrostatic or coordinative interactions. The external mass transfer coefficient ( K f ) of Cr(VI) over TiO 2 /AC-AEMP was estimated as 1.75 × 10 −6 m s −1 , which was ~ 12.79 and ~ 5.96 times that of TiO 2 and TiO 2 /AC, respectively. Dense and homogeneous heterojunctions between AC and TiO 2 were acquired synchronically by forming Ti–O–C linkages, which increased traveling of electrons from TiO 2 to AC. Accordingly, Cr(VI) can capture photo-induced electrons on the surface of AC via concrete routes and then be reduced efficiently. The results showed that the photoreduction rate of Cr(VI) on TiO 2 /AC-AEMP reached to ~ 92.7%, and the overall photocatalytic activity of this well-designed TiO 2 /AC-AEMP has been enhanced significantly by 5.5 times compared to TiO 2 /AC. The enhanced photocatalytic activity of TiO 2 /AC-AEMP was mainly attributed to an improved synergetic process of mass transfer–induced adsorption–photoreduction by forming specific transfer routes for accelerative motion of Cr(VI) and electrons. This work provides a feasible strategy to improve the photoactivity of photocatalysts for the degradation of pollutants by effective mass transfer.
Graphical abstract
研究领域:
环境科学
·
材料科学
✓ 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）