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.
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高影响因子
ACS Omega
·
2020
·
IF 2.87
Jia Yang,Mingyan Fu,Mingdan Tan,Yanling Tian,Xiaorui Sun,Huisheng Huang
Herein, a 3.0%-Au/Sr0.70Ce0.20WO4 sample was prepared for the photocatalytic reduction of the Cr2O72– ion. The photocatalyst was characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and ultraviolet–visible diffuse reflectance spectra. The Sr0.70Ce0.20WO4 sample presented a photocatalytic reduction activity that is better than those of the Ce-doped sample and the intrinsic sample. Thereafter, different metal elements, Cu, Ag, Au, and Pt, were used as cocatalysts, which were loaded on the Sr0.70Ce0.20WO4 sample. The 3.0%-Au/Sr0.70Ce0.20WO4 photocatalyst showed optimal photocatalytic reduction activity in a 8 vol % methanol solution (pH = 7) under visible light irradiation. The kinetic constant of the optimal one is 0.0039 min–1, which is 1.86 times that of the Sr0.70Ce0.20WO4 sample. The photocatalyst is stable enough after a 24 h photocatalytic experiment.
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PubMed
高影响因子
Analytical Methods
·
2019
·Vol. 11
·期 45
·5819-5825
·
IF 2.378
Shunzhen He,Xi Lin,Hao Liang,Fubing Xiao,Feifei Li,Can Liu,Pengfei Fan,Shengyuan Yang,Yong Liu
As a priority pollutant in the environment, hexavalent chromium (Cr(VI)) has received increasing attention. In this work, a safe, simple, low-cost, effective and sensitive colorimetric strategy for the determination of Cr(VI) was introduced based on polyvinylpyrrolidone (PVP) functionalized silver nanoparticles (PVP–AgNPs). The prepared PVP–AgNPs had good dispersibility, and exhibited a state change from dispersed to aggregated when Cr(VI) was present in pH 5.5 PBS buffer due to the special and strong coordination between PVP and Cr(VI), accompanied by a color change from bright yellow to orange. Under the optimized conditions, the concentration of Cr(VI) in the range of 1.0 × 10−7 M to 2.4 × 10−6 M showed a good linear relationship with the ratio of the absorbance at 530 nm to that at 390 nm (A530 nm/A390 nm), and the limit of detection (LOD) was 34 nM. The method also showed good precision and high repeatability in determining Cr(VI) in real water samples such as pond water, tap water and river water. The recoveries ranged from 93.5% to 104.3%, indicating the method can be used for an extensive range of practical applications.
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高影响因子
JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY
·
2015
·Vol. 15
·期 8
·6103-6107
·
IF 1.556
Zhang Jing,Zhang Guilong,Zheng Kang,Cai Dongqing,Wu Zhengyan
Urea was used to disperse nanoscale zero-valent iron (NZVI) for reduction of Cr(VI) to Cr(III) in aqueous solution. Scanning electron microscope and fourier transform-infrared spectra investigations demonstrated that urea could effectively increase the dispersion of NZVI resulting in
more effective reduction sites (ERS) for Cr(VI) ions. Batch reduction experiments indicated that the reductive capacity of urea dispersed NZVI (UNZVI) was significantly improved, as the reductive efficiency reached 96.8% under optimal condition compared with the raw NZVI (72.14%). Additionally,
the NZVI was stable for at least 28 days after urea treatment. The dispersion mechanism was proposed that the steric hindrance effect of the urea coating on the surface might play a key role in dispersing the NZVI particles.
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高影响因子
BIORESOURCE TECHNOLOGY
·
2019
·
IF 6.669
Jingya Ren,Guilong Zhang,Dongfang Wang,Dongqing Cai,Zhengyan Wu
In this work, cornstalk (CS) was irradiated by high energy electron beam to obtain honeycomb-like porous CS (PCS). The PCS was loaded with ammonium sulfite (AS) and then coated by polyvinyl alcohol (PVA)-Fe 3 O 4 to obtain PCS-AS@PVA-Fe 3 O 4 . The PCS-AS@PVA-Fe 3 O 4 could reduce hexavalent chromium (Cr(VI)) to trivalent chromium (Cr(III)) by SO 3 2− , then the Cr(III) combined with PCS-AS@PVA-Fe 3 O 4 through hydrogen bonds. The resulting PCS-AS@PVA-Fe 3 O 4 /Cr with a high magnetism could be conveniently separated from water via a magnet. PCS-AS@PVA-Fe 3 O 4 /Cr showed a high performance on controlling Cr(VI) migration in soil and uptake by plant. Meanwhile, ammonium could be released from PCS-AS@PVA-Fe 3 O 4 , favoring plant growth. Therefore, this work not only provides a promising and low-cost approach to remove Cr(VI) and promote plant growth simultaneously, but also provides a new route for CS recycling, which might have a potential application value.
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高影响因子
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.
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高影响因子
CHEMOSPHERE
·
2018
·
IF 4.427
Wei Zhang,Shilu Zhang,Jing Wang,Meng Wang,Qiulai He,Jianyang Song,Hongyu Wang,Jinping Zhou
In this study, we prepared a novel hybrid functionalized chitosan-Al 2 O 3 @SiO 2 composite (FCAS) for removing hexavalent chromium [Cr(VI)] from aqueous system. Spectroscopic studies like Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and energy dispersive spectroscope (EDS) were characterized. The effects such as dosage of adsorbent, pH, contact time and initial Cr(VI) concentration were evaluated. It has been illustrated that a wide acidic condition in the pH range of 2–6 was conducive to Cr(VI) adsorption and only 10 min was required to reach about 80% adsorption. Also, the adsorption properties of prepared adsorbent such as kinetics, thermodynamics and isotherms were comprehensively studied. Additionally, the adsorption capacity barely declined even after five cycles. Studies found that FCAS with characteristics of high performance of adsorption rate and capacity and better reusability would be a potential adsorbent for wastewater treatment .
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高影响因子
Journal of Environmental Chemical Engineering
·
2018
·
IF 0
Sefiu Abolaji Rasaki,Bingxue Zhang,Siqi Liu,Tiju Thomas,Minghui Yang
ZnO@TiCN nanourchin composites are synthesized via a solid–solid separation process followed by a wet deposition method. The composite contains TiCN nanourchins, metallurgically connected to ZnO ; the system adsorbs Cr(VI) following a pseudo-first order kinetics. This heterostructure has substantial ability to thermochemically convert the adsorbed Cr (VI) to Cr (III). Complete removal of Cr (VI) is achieved, even in the <10 ppm concentration regime. The effect of reaction time, temperature, pH value, adsorbent loading, initial concentration of Cr (VI), and thermodynamic parameters are systematically investigated. Van’t Hoff’s plot based analysis indicates that the entropy change associated with physisorption process involved is significantly positive (∼18 kJ/mol K). The process is also substantially endothermic (△H ∼ 5 kJ/mol). Kinetics improves with temperature up to 90 °C. The high entropy associated with the adsorption is attributed to a high heterogeneity factor of ∼3.9. Pseudo-second order is the best kinetic model to describe the adsorption of Cr(VI) onto the surface of ZnO@TiCN; both Freundlich and Langmuir isotherms describe the adsorption observed. Over 4 regeneration cycles, an adsorption capacity retention of >90% is observed. This novel adsorbent, with its hierarchical structure, and properties reported here, suggest that it could find applications in contemporary waste water treatment processes.
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Desalination and Water Treatment
·
2024
·
IF 1
Fengli Shao,Shaoyu Zhou,Jiaxin Xu,Qiong Du,Jianqiu Chen,Jingge Shang
Nanoscale zero-valent iron (nZVI) has been proven to be more effective for the treatment of hexavalent chromium(Cr(VI)) when modified with the transition metal Cu. In this study, biochar-supported Cu/Fe bimetallic nanoparticles (Cu-nZVI/BC) were prepared and used for Cr(VI) removal from aqueous solution. The effects of the pH value, the initial concentration of Cr(VI), coexisting ions and humic acids (HA) were investigated. The compositional structures of Cu-nZVI/BC were analyzed by transmission electron microscopy, scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The maximum removal efficiency of Cr(VI) was 50.57% (126.41 ± 3.75 mg g –1 ) for Cu-nZVI/BC at pH 2. The adsorption kinetic data were in agreement with the pseudo-second- order model, which confirmed that the adsorption step was a chemical adsorption and reduction process. The presence of Ca 2+ and NO 3 – had an inhibitory effect on Cr(VI) removal, while dHA increased the removal efficiency at high concentrations. This study proves that Cu-nZVI/BC removal of solution Cr(VI) is feasible and shows significant potential in practical applications.
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高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2026
·
IF 12.5
Ting Zhao,Yanjing Wang,Lei Li,Pengyu Gong,Mingrui Yang
An oxalic acid-based remediation method enables deep Cr(VI) reduction and Cr removal. • Oxalic acid dissolves refractory Cr(VI) species and removes Fe Cr associated Cr(III). • Cr(VI) speciation-guided processes achieve efficient remediation of diverse soils. • One-step and two-step treatments address different Cr(VI) contamination scenarios. • Plant-derived oxalic acid provides an environmentally benign reagent. The complex distribution of Cr(VI) species in contaminated soils limits the effectiveness of conventional reduction methods, which often fail to achieve regulatory targets and result in the accumulation of substantial Cr(III) residues. In this study, a thermally activated oxalic acid reduction strategy was developed based on the molecular characteristics of Cr(VI) and Cr(III) species in soils, enabling deep Cr(VI) reduction and simultaneous total chromium removal. For soils with high proportions of adsorbed Cr(VI) but limited water-soluble Cr(VI), a one-step thermally activated oxalic acid treatment reduced Cr(VI) concentrations below the regulatory limit (5.7 mg kg −1 ) and removed approximately 80% of total chromium. In contrast, soils dominated by water-soluble Cr(VI) were effectively remediated through a two-step process involving water washing followed by thermally activated oxalic acid reduction, achieving regulatory compliance and substantial total chromium removal. Mechanistically, oxalic acid enables near-complete reduction of stably coordinated Cr(VI) via a dissolution-release-reduction pathway, while other adsorbed Cr(VI) species are reduced through dissolution-reduction or direct reduction pathways. Meanwhile, the predominant Cr(III) species Fe Cr coprecipitate in the soil is simultaneously dissolved by oxalic acid. After remediation, residual Cr is mainly retained as highly stable residual Cr(III) species with minimal environmental risk. The oxalic acid filtrate can be regenerated via ion exchange treatment and reused for subsequent reduction, and oxalic acid itself, as a common plant root exudate, serves as an environmentally benign reagent. Moreover, this method is applicable to different soils with varying textures and Cr(VI) speciation, providing a potentially sustainable approach for the remediation of Cr(VI)-contaminated soils. Download: Download high-res image (265KB) Download: Download full-size image
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高影响因子
ChemistrySelect
·
2026
·Vol. 11
·期 29
·e73937
·
IF 2.3
Yingjian Liao,Wenqi Xu,Liang Zeng,Songyun Deng,Xiaomao Hu,Song Lei,Linping Chen,Li li Geng,Shu Chen
Hexavalent chromium (Cr(VI)) is a highly toxic heavy metal contaminant commonly used in industrial applications, posing significant risks to human health and environmental sustainability due to its persistence and difficulty in degradation. Transition metal carbide (MXene) is an emerging two-dimensional material that has gained considerable attention for its potential in water pollutant removal. However, poor MXene stability and limited functional groups restrict its specific adsorption of target metal ions such as Cr(VI). Herein, a novel functionalized three-dimensional MXene composite gel (M/D/P) was synthesized via a photo-induced thiol-ene click reaction using MXene as the framework material. The multithiol-functionalized framework introduces abundant thiol groups, which facilitate the reduction of Cr(VI) to less toxic Cr(III) and enable chelation of Cr(III) with the adsorbent, driven by proton depletion during reduction. The adsorption behavior follows pseudo-second-order kinetics and the Langmuir model, indicating a chemical adsorption process. The maximum removal capacity reaches 347.71 mg·g − 1 , and the gel maintains 80% of its initial adsorption capacity after five cycles. The synergistic adsorption-reduction mechanism, involving electrostatic attraction, reduction, covalent bonding, and chelation, highlights M/D/P as a promising MXene-based adsorbent for water treatment applications. Graphical A multithiol-functionalized MXene composite gel (M/D/P) is synthesized via photo-induced thiol-ene click reaction. The abundant thiol groups enable synergistic adsorption–reduction of Cr(VI) through electrostatic attraction, chemical reduction, and chelation. The material achieves 374.71 mg·g − 1 removal capacity with excellent reusability.
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高影响因子
Polymers
·
2021
·Vol. 13
·期 7
·1035
·
IF 4.329
Chengbing Yuan,Yan Zhang,Jinshui Yao,Qinze Liu,Fan-Gong Kong
Herein, a synthetic strategy for a rough microsphere Cr(VI)-adsorbent via the reaction of tannic acid (TA) and 1,6-hexanediamine (HA) and using polyethylene glycol (PEG) as surface modifier was presented. This adsorbent was characterized by a Fourier Transform Infrared spectrometer (FTIR), thermogravimetic analysis (TGA), X-ray photoelectron spectroscopy (XPS), etc. Certain factors, including contact time, PEG@poly(tannin-1,6-hexanediamine) (PEG@PTHA) dosage, initial concentration, and experimental temperature affecting the Cr(VI) adsorption performance of adsorbent were explored. PEG@PTHA can adsorb Cr and the Cr(VI) was reduced up to Cr(III) due to the existence of phenolic hydroxyl groups. Its adsorption capacity can reach up to 300 mg/g within 10 min and approximately 100% removal percentage below the initial concentration of 100 mg/L. Its behavior matched well with the Langmuir isotherm model and pseudo-second-order kinetic model. A PEG@PTHA adsorbent with maximum adsorption capacity (450 mg/g) has great prospects in Cr(VI)-sewage treatment.
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高影响因子
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