ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2019
·Vol. 26
·期 11
·11126-11139
·
IF 2.914
Li Zhenyuan,Pan Zhidong,Wang Yanmin
A raw illite-smectite mixed-layered clay (RI/S) was ground for preparing nano-sized I/S clay (NI/S) and subsequently amino-functionalized via grafting of 3-aminopropyltrithoxysilane (APTES) (NH 2 -RI/S and NH 2 -NI/S, respectively). The samples were characterized by particle size analysis, specific surface area measurement, X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and 29 Si nuclear magnetic resonance ( 29 Si NMR). Compared to RI/S, NI/S has a narrow particle size distribution and appears in a platelet-like morphology due to the disintegration/exfoliation of RI/S after grinding. Based on the 29 Si NMR spectra, the appearances of tri-silicate units indicate the chemically grafting of APTES molecules on NH 2 -RI/S and NH 2 -NI/S, respectively. NH 2 -NI/S can adsorb greater amounts of Pb(II) cations and Cr(VI) anions rather than NH 2 -RI/S since NH 2 -NI/S grafts more amounts of amine groups (-NH 2 ). The isotherm data for adsorption of Pb(II) cations and Cr(VI) anions can be described by the Langmuir model at different temperatures (i.e., 10 °C, 30 °C, and 50 °C), respectively. The maximum adsorption amounts of Pb(II) cations and Cr(VI) anions onto NH 2 -NI/S calculated by the Langmuir isotherm model are 131.23 mg/g and 36.91 mg/g at 50 °C, respectively. The adsorptions of Pb(II) cations and Cr(VI) anions onto NH 2 -NI/S involve in the surface complexation of NI/S and amine groups.
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高影响因子
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
·
2019
·
IF 2.722
Xinbo Jing,Xueying Peng,Xiyin Sun,Wu Zhou,Wei Wang,Shufen Wang
In this study, a facile impregnation-calcination strategy was applied in order to synthesize Mo2C modified MoO3 (Mo2C/MoO3), which was then employed as catalyst for the photoreduction of Cr (VI) and photodegradation of methyl orange (MO) upon irradiation by visible light (λ > 400 nm). The apparent rate constant (k) of Mo2C/MoO3 for the MO photocatalyzed degradation reaction under visible-light irradiation was found to be 0.0171 min-1, which was 4.59 and 67.38 times higher than that of Pt/MoO3 and pristine MoO3, respectively. Study of the photocatalytic mechanism revealed that the •O2- species played a major role in MO degradation. Moreover, the addition of Mo2C enhanced the light response region of MoO3, and also promoted the photocatalytic activity of MoO3. This was due to the enhanced separation efficiency of photogenerated electron-hole pairs and broader photoresponse region. This work suggests a new use for the easily accessible Mo2C/MoO3 heterostructure and could facilitate the application of photocatalysts for wastewater treatment．
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ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY
·
2018
·
IF 3.974
Peng Chen,Na Geng,Dong Zhou,Yiran Zhu,Yuliang Xu,Kangping Liu,Yongxia Liu,Jianzhu Liu
Hexavalent chromium (Cr(VI)) is a common environmental pollutant. Exposure of Cr(VI) can lead to cell autophagy, but the preventive measures for diminishing Cr(VI)-induced autophagy need further study. COX-2 can be induced by several heavy metals and can lead to endoplasmic reticulum (ER) stress and autophagy; thus, COX-2, ER stress, and autophagy may be related. This study mainly investigated the role of COX-2 in the eIF2α-ATF4 pathway, which is a major pathway in cell autophagy. In this study, Cr(VI) was used as a xenobiotic to determine changes in the parameters of ER stress, autophagy, and COX-2 levels. At the same time, a clear contrast was obtained by assigning positive and negative controls of ER stress and autophagy. The results showed that during Cr(VI) invasion, the parameters of ER stress and autophagy (such as BiP, PERK, p62, LC3-II, and mTOR) were enhanced, similarly to the positive control of ER stress and/or the autophagy controls. Such enhancement is a protective mechanism for cell survival. Additionally, the COX-2 levels increased. Moreover, when COX-2 was inhibited, the PERK level remained high, whereas the LC3-II level decreased. This finding suggests that COX-2 specifically affects the interaction between ER stress and autophagy. Notably, this study reveals that Cr(VI) can induce ER stress and autophagy in DF-1 cells and that COX-2 plays an essential role in the interaction between ER stress and autophagy.
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高影响因子
CARBOHYDRATE POLYMERS
·
2018
·
IF 5.158
Shuping Wu,Xiangzi Dai,Tingting Cheng,Songjun Li
A sensitive and selective electrochemical sensor based on ion-imprinted chitosan-graphene nanocomposites (IIP-S) has been developed for the determination of Cr(VI). The ion-imprinted polymers were constructed by one-step electrodeposition. The morphology and structure of IIP-S were characterized by SEM, TEM , XRD, FTIR and EDS , respectively. Meanwhile, the electrochemical behavior of IIP-S was investigated using CV , EIS and DPV . The linear range of IIP-S was from 1.0 × 10 −9 to 1.0 × 10 −5 mol/L, with the low detection limit of 6.4 × 10 −10 mol/L (S/N = 3). The sensor exhibited high selectivity for the determination of Cr(VI) in the presence of Zn(II), Co(II), Cu(II), Ni(II), Mn(II), MnO 4− , C 2 O 4 2− , S 2 O 6 2− and MoO 4 2− ions. The IIP-S also provided excellent stability and good repeatability that the sensitivity remained 85% after 9 cycles of rebinding-removal, while the sensitivity retained 87% of its initial response storing at 4 °C for 17 days. Moreover, it was successfully applied to the detection of Cr(VI) ions in tap water and river water.
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高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2018
·
IF 3.927
Xiangyu Wang,Tao Wang,Jun Ma,Huiling Liu,Ping Ning
A novel composite based on hydrophilic boehmite-PVB/PVDF blended membrane- immobilized nanoscale zero-valent iron (nZVI) (BPPN) was synthesized. When the initial concentration of Cr(VI) was 20 mg/L, 100% Cr(VI) was removed by BPPN at an initial pH of 4.08 under room temperature of 25 °C within 90 min. In addition, the reactivity of the regenerated BPPN composites toward Cr(VI) removal were not obviously declined after 6 cycles. The resultant BPPN demonstrated high reactivity, preeminent stability and reusability in the reaction course. Meanwhile, the BPPN composites showed a higher removal efficiency toward the removal of Cr(VI) compared with alumina-PVB/PVDF-nZVI (APPN) composites. The plentiful hydroxyl groups of boehmit on the BPPN surface resulted in the enhancement in hydrophilicity and improved Fe 0 loading of the BPPN composites. For environmental parameters, results indicated that there was a negative effect of increasing the initial concentration or decreasing reaction temperature toward the removal of Cr(VI) by BPPN, and that the acidic and neutral conditions showed more favorable effect on Cr(VI) removal than the alkaline ones. The generated ferrous ions on the surface of BPPN were certified to play an important role in removal of Cr(VI). XPS analysis suggested that the reduction reaction of Cr(VI) occurred on the surface of the composite and produced precipitation of Cr(III). The Cr(VI) removal by BPPN composite was found to follow a revised kinetics well. This study suggests that the novel BPPN composite possessing excellent performance may be a promising functional material of heavy metal wastewater treatment.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2025
·
IF 9
Meijun Liu,Yuxin Wang,Yueqi Chen,Tingting Zhang,Zhenbin Zhang,Houfen Li,Fengjun Shan,Taigang Ma
Hexavalent chromium (Cr(VI)) is one of the hazardous pollutants in wastewater because of acute toxicity and superb solubility. Graphene oxide (GO) is the promising adsorbent to handle Cr(VI), however, the drawbacks of easy aggregation, limited adsorption sites, unable valence changes and difficult recyclability hinder its further applications. In this study, Fe 3 O 4 modified L-glutamic acid functionalized graphene oxide (M−Glu/GO) was synthesized for Cr(VI) decontamination by the solvothermal method for effectively offsetting the above shortcomings. From characterization results, M−Glu/GO carried the traits of the relatively bigger surface area, abundant active sites, favorable surface charges and stable magnetic property. Cr(VI) adsorption process by M−Glu/GO was conformed to the pseudo-second order kinetic model with fast adsorption rate ( k 2 = 1.75 × 10 –3 g·mg −1 ·min −1 ) and Freundlich isotherm model with the maximum adsorption capacity of 75.63 mg·g −1 at 308 K, far more exceeding than GO (6.38 mg·g −1 ). Surprisingly, with the help of oxygen-containing groups, amine groups and Fe 3 O 4 with ample electron supplement, M−Glu/GO was capable of transforming partly Cr(VI) into Cr(III), realizing the detoxification. It exhibited practical application potentials with magnetic separation under various water matrices and kept a relative adsorption capacity of 70 % after 8 cycles. Furthermore, six interactions, involving pore filling, hydrophilic interactions, coordination interactions, anion-π interactions, electrostatic interactions and adsorption-reduction, witnessed the satisfied Cr(VI) adsorption by M−Glu/GO. This work paves a feasible way to accelerate the Cr(VI) adsorptive removal, and provides a vivid case for developing recyclable GO-functionalized adsorbents.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2025
·
IF 9
Fulin Wang,Helin Hua,Hui Jia,Dingying He,Zhongyou Jiang,Jiaxin Cao,Shanshan Dong,Zhenxing Zeng,Suhua Chen
The construction of heterojunction is considered to be an effective way to promote the photocatalytic activity, while it is always challenging due to the mismatched lattices of heterojunctional materials and results in an unsatisfactory enhancement of charge carrier separation. It is critical to overcome that lattice mismatch and establish charge transfer channels in heterojunction for achieving high charge transfer and separation. In this study, a red phosphorus/phosphorus doped graphitic carbon nitride (RP/P-CN) type I heterojunction was constructed to boost interfacial charge transfer for Cr(Ⅵ) photoreduction through in situ growing RP on g-C 3 N 4 nanosheets. The formed P − N bonds around interfaces in the RP/P-CN allowed photoexcited charge to rapidly transfer from the conduction band of P-CN to that of RP, which contributed to the significant achievement of Cr(Ⅵ) reduction. The constructed interfacial charge transfer channels largely promoted the photoexcited charge carrier separation in the RP/P-CN. Additionally, the simultaneous RP formation and P doping significantly enhanced the visible light response and the adsorption efficiency of Cr(Ⅵ). As a result, RP/P-CN 1:5 could achieve 99.1 % removal of Cr(Ⅵ) after 20-min visible light irradiation with an achieved apparent kinetic rate constant (k app ) of 0.2289 min −1 , which were much better than the 19.2 % of Cr(Ⅵ) removal by pure g-C 3 N 4 and presented a 21-fold higher k app than pure g-C 3 N 4 (0.0108 min −1 ) achieved, respectively. This study provides a new strategy to design an efficient g-C 3 N 4 based metal-free heterojunction for Cr(Ⅵ) photoreduction.
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Analytical Methods
·
2017
·Vol. 9
·期 30
·4471-4475
·
IF 1.9
L. F. Tian,D. S. Zou,Y. C. Dai,L. L. Wang,W. Gao
Quantification of chromium in V–Cr–Ti ternary alloys, used as candidate structural materials for fusion reactors, is essential in view of its significant effect on the properties of these vanadium-based alloys. Various methods have already been used for the determination of chromium in common alloys, but most of these methods are based on complicated and expensive instruments or suffer from the serious matrix interference of vanadium. In this study, a simple, rapid and accurate spectrophotometric method was developed for the determination of chromium in V–Cr–Ti alloys without any prior separation and chromogenic agent. The alloy samples were dissolved in diluted sulphuric acid and concentrated nitric acid, and chromium was oxidized with persulphate in the presence of Ag(I) ions as a catalyst. After alkalization of the solution with sodium hydrate, greenish-yellow coloured chromate (CrO42−) ions were formed in the alkaline solution and had a maximum absorption peak at 374 nm. Beer's law was obeyed in the range of 0.15–12.0 μg mL−1 Cr(VI) at 374 nm and the molar absorptivity was 4.8 × 103 L mol−1 cm−1. All the variables were studied in order to optimize the analytical conditions. Vanadium and titanium seriously interfered with the determination of Cr(VI) and their interference can be eliminated by addition of ammonium tartrate. The proposed method is simple, fast, accurate and of low cost, and has been satisfactorily used for the determination of chromium in V–Cr–Ti alloys. The results are in good agreement with data given by inductively coupled plasma optical emission spectrometry (ICP-OES) and the relative standard deviation is found to be lower than 0.4%.
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CATALYSIS LETTERS
·
2015
·Vol. 145
·期 10
·1913-1921
·
IF 2.307
Wu Jing,Zhi Yunfei,Shan Shaoyun,Su Hongying,Wu Shuisheng,Jia Qingming
Abstract Polypyrrole(PPy) supported Cr(III)(salen)Cl catalyst was prepared for alternating copolymerization of cyclohexene oxide and carbon dioxide. The supported catalyst and the copolymerization products were characterized by FTIR, XRD, XPS, ICP-MS, SEM, TEM, NMR, gel permeation chromatography, thermogravimetric analysis and differential scanning calorimetry. After the study, we concluded that the homogeneous Cr(III)(salen)Cl is successfully supported on the PPy, and its catalytic performance is much better than the homogeneous one. Moreover, the copolymerization product catalyzed by PPy-Cr(III)(salen)Cl exhibits higher molecular weight, narrower molecular weight distribution, superior thermal stability and selectivity. Graphical Abstract
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高影响因子
APPLIED CATALYSIS A-GENERAL
·
2013
·
IF 3.41
Zhiguo Sun,Gang Li,Hai-ou Liu,Liping Liu
A series of MOF-based catalysts, metal-salen complexes incorporated into amino-functionalized MIL-101 matrices by salicylaldehyde condensing to amino group and coordinating metal ion through one pot method, have been prepared and characterized. The successful preparation of catalysts demonstrates that postsynthetic modification (PSM) is a practical and powerful route to generate MOF-based catalyst with multiple active sites. The catalytic performances of prepared catalysts were investigated via selective oxidation of cyclohexane to cyclohexanone and cyclohexanol (KA-oil) by molecular oxygen in the absence of solvent. It was found that NH 2 -MIL-101(Cr)-Sal-Co, as a typical case, behaves as cooperative catalyst for cyclohexane selective oxidation. That is, salen-Co(II) attached to framework of MOF is able to assist in the generation of new radicals from peroxides via a Haber–Weiss catalytic cycle to promote conversion of cyclohexane while framework Cr ion is able to catalyze the dehydration of intermediate product cyclohexyl hydroperoxide (CHHP) to improve KA-oil selectivity. Furthermore, this catalyst exhibits good recyclability and behaves as truely heterogeneous catalyst.
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RSC Advances
·
2017
·Vol. 7
·期 64
·40227-40236
·
IF 3.108
Ran Li,Qing-Da An,Zuo-Yi Xiao,Bin Zhai,Shang-Ru Zhai,Zhan Shi
In view of the sustainable character and high-density of reactive sorption sites, a new kind of poly(ethylenimine)/chitosan (PEI/CS) aerogel beads were successfully synthesized using controllable sol–gel and freeze drying methods, with the aim of using them for efficient Cr(VI) removal from aqueous acid solutions. Compared with the reported CS-based sorbents for hexavalent chromium [Cr(VI)], not only is the synthetic process used simple but the bead-like samples could be easily separated from solutions for recycling. Structural characterization and batch experiments were compared to illustrate the adsorption performance of the aerogel beads which were synthesized using various processes. Out of the three samples (CS–glutaraldehyde (GA), CS–GA–PEI and CS/PEI–GA beads), the one referred to as CS–GA–PEI exhibited the highest adsorption capacity and the maximum amount of Cr(VI) removal was 402.9 mg g−1 at pH 2.0 and 298 K. The pseudo-second-order and Langmuir model preferably fitted the adsorption process best. After five cycles of desorption–regeneration tests, more than 80% of Cr(VI) could still be removed by these newly designed CS–GA–PEI beads. Adsorption mechanisms could be explained using electrostatic attraction and reduction reaction theories, on the basis of comprehensive analysis. More importantly, taking advantage of the micrometer sized particles and three-dimensional network that developed, fixed-bed column tests were also conducted on the resultant bead-like sample, which also exhibited excellent sorption performance under testing conditions. These superiorities of CS–GA–PEI beads make them a potential candidate for use in remediating the pollution caused by Cr(VI) ions.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2025
·
IF 9
Shiyu Zhang,Li Li,Zhiwei Zhao,Yu Li,Li Shen,Sai Zhang
Biochar, being a cost-effective material, is widely used for water pollution control. However, the further degradation of most contaminants is limited due to the weak electron donor properties of raw biochar. Herein, we combined banana peel biochar with microscale zero-valent aluminum (mZVAl) using ball milling technology and demonstrated the effective chromium removal by the composite. Nearly complete removal of Cr(VI) could be achieved within 30 mins, alongside an impressive efficiency of 98.08% in total Cr elimination. Multiple parameters, including water matrices, composite ratio (m mZVAl /m biochar ), and initial solution pH, were explored. Additionally, detection of Cr species revealed that aqueous Cr(VI) was reduced to Cr(III) via chemisorption, followed by the formation of Cr(OH) 3 , which adhered to the surface of the composite. Structural analysis showed that the pristine mZVAl deformed into the plate-like structure under mechanical forces, with biochar distinctly embedded in the mZVAl matrix, increasing lattice spacings. Mechanistic studies suggested that mZVAl acted as the ‘electron donor’, while biochar functioned as the ‘electron shuttle’, accelerating electron transfer through galvanic cell structures. This study clarifies the electron-dominated mechanism in Cr(VI) removal and provides technical support for heavy metal elimination.
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