RSC Advances
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2016
·Vol. 6
·期 32
·27039-27046
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IF 3.289
Honglin Yao,Qianqian Ding,Hongjian Zhou,Zhenfu Zhao,Gang Liu,Guozhong Wang
In this study, mesoporous amino-group functionalised iron/silica hollow spheres (Fe/SiO2–NH2 HSs) were successfully developed as a magnetic absorbent for the highly effective removal of Cr(VI) ions. The Fe/SiO2–NH2 HSs were synthesized using monodispersed silica colloids as a chemical template, followed by a one-pot hydrothermal treatment, hydrogen reduction and surface modification with an amino silane coupling agent. The Fe/SiO2–NH2 HSs have a diameter of ca. 950 nm and a shell thickness of ca. 60 nm, and the surfaces were composed of Fe and SiO2 units with amino functional groups. Meanwhile, the ferromagnetic property endowed them with easy recyclability for practical applications. The Fe/SiO2–NH2 HSs exhibited significantly improved ability to remove pollutant Cr(VI) and methyl orange. The removal percentage of Cr(VI) (8 mg L−1) could reach 98.3% in just 5 min using Fe/SiO2–NH2 HSs; however, only 10% of Cr(VI) were removed using the unmodified samples. XPS analysis suggested that the removal of Cr(VI) was attributed to the adsorption and reduction synergistic process of the Fe/SiO2–NH2 HSs. During the process, an electrostatic attraction occurred between the positively charged amino-groups and the negatively charged pollutant species in the aqueous solution, and adsorbed Cr(VI) ions were reduced to Cr(III) species by the iron of Fe/SiO2–NH2 HSs.
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SENSORS AND ACTUATORS B-CHEMICAL
·
2016
·
IF 4.758
Wan Wang,Hua Bai,Haiyu Li,Qing Lv,Qing Zhang,Ning Bao
Fabrication of disposable gold working electrodes in bulk is desirable for their extensive application in electrochemical detection . In this paper the gold film electrodes were prepared by sputtering the gold film with the thickness of ∼12 nm on the double sided conductive carbon tape. The gold film coated carbon tape could be used like stickers with small square pieces and attached on ITO glass for fabrication of disposable gold film electrodes. The electrochemical responses of the gold film modified electrodes on Cr(VI) in acidic solutions were similar to previous gold electrodes, suggesting the similar mechanism as before. Cr(VI) could be determined by the amperometric method with the detection limit of 0.7 μg L −1 (0.013 μM), which was significantly improved compared with previously reported disposable gold-based electrodes. The batch-by-batch (n = 20) reproducibility of the fabricated electrodes was 7.3% at 50 μg L −1 and 3.8% at 5.0 mg L −1 , respectively. The disposable electrodes could be applied to quantify Cr(VI) in real samples including plastics, tap water and lake water with results in agreement with those obtained with HPLC-ICP-MS. This study provides a simple and effective alternative for preparation of disposable gold film electrodes.
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SCIENCE OF THE TOTAL ENVIRONMENT
·
2016
·
IF 3.976
Zunwei Chen,Shufang Song,Yuezhong Wen
The priority pollutant chromium (Cr) was ubiquitous and great efforts have been made to reduce Cr (VI) into less-toxic Cr (III) by alga for the convenient availability and low expense. However, the functional role of organelle inside the algal cell in Cr (VI) reduction was poorly understood. In this study, organelles in green algae Chlorella vulgaris were extracted and further decorated for Cr (VI) reduction tests. Results showed that the chloroplast exhibited not only adsorption ability of total Cr (21.18% comparing to control) but also reduction potential of Cr (VI) (almost 70% comparing to control), whose most suitable working concentration was at 17 μg/mL. Furtherly, the isolated thylakoid membrane (ITM) showed better Cr (VI) reduction potential with the presence of sodium alginate (SA), even though the Hill reaction activity (HRA) was inhibited. As for photosystem II (PSII), the addition of mesoporous silica SBA-15 enhanced the reduction ability through improving the light-harvesting complex (LHC) II efficiency and electron transport rate. On the whole, the reduction ability order of the three kinds of materials based on chloroplast in C. vulgaris was PSII@SBA-15 > Chloroplast > ITM@SA. The attempt made in this study to reduce the Cr (VI) with C. vulgaris organelles might not only offer basement to detect the potential action mechanism of Cr (VI) reduction by C. vulgaris but also provide a new sight for the scavenge of heavy metal with biological materials.
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CHEMICAL ENGINEERING JOURNAL
·
2017
·
IF 6.216
Si-Hai Zhang,Mei-Feng Wu,Ting-Ting Tang,Qiu-Ju Xing,Cai-Qing Peng,Fei Li,Hui Liu,Xu-Biao Luo,Jian-Ping Zou,Xiao-Bo Min,Jin-Ming Luo
In this study, nanoscale zero-valent iron (nZVI) with a considerably high surface area (182.97 m 2 ·g −1 ) and featured morphology of chain structure has been synthesized and well characterized. The as-prepared nZVI on can totally remove Cr(VI) under anoxic condition after 20 min reaction, whereas only 43% of Cr(VI) was removed after 60 min reaction under oxic condition. Noteworthily, the nZVI exhibits excellent removal capacity of Cr(VI) (123.85 mg/g) and fast removal rate (0.017 g·mg −1 ·min −1 ), much better than those reported in the literatures except for that reported by Li et al. (2008) [1] . Experimental results have confirmed that only FeCr 2 O 4 with low compactness was generated under anoxic and acidic conditions in the new process. And it is evident that the formation of the passivation layer which contains oxides and hydroxides (or (oxy)hydroxides) of iron and chromium were well hindered. Furthermore, the as-prepared nZVI has shown fast removal of traced Cr(VI) from the Cr-spiked drinking water or actual Cr-contaminated lake water. Accordingly, we proposed a new reaction process of Cr(VI) reduction by nZVI under anoxic condition. And we firstly make clear the detailed process of Cr(VI) removal by the as-prepared nZVI via X-ray photoelectron spectrometer (XPS) analysis in time scale. Meanwhile, the excellent Cr(VI) removal performance of the as-prepared nZVI could be attributed to (i) the high surface area, (ii) large quantity of active sites of nZVI, and (iii) fast electron transfer from the nZVI/FeCr 2 O 4 to Cr(VI). The present work not only provides the potential materials for the application to the rapid and high-efficient removal of Cr(VI) from aqueous solution, but also proposed a new avenue for hindering the passivation of Fe 0 . And a detailed mechanism of the Cr(VI) removal by nZVI was proposed for the first time.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2013
·
IF 2.206
Zhiqiao He,Qiaolan Cai,Ming Wu,Yuanqiao Shi,Huiying Fang,Lingdan Li,Jiancheng Chen,Jianmeng Chen,Shuang Song
In the present work, reduction of Cr(VI) induced by UV–visible light in aqueous solution was investigated. The aqueous medium contained TiO2 nanosheets and no additional reducing agents or hole scavengers. A hydrothermal method was used to synthesize fluorinated TiO2 nanostructures with various percentages of exposed {001} facets and initial F/Ti ratios. Fluorine-free TiO2 nanosheets were obtained by washing the TiO2 samples with NaOH solution. The surface fluorination facilitates the adsorption process by increasing the number of surface OH groups generated. Moreover, fluorination efficiently inhibits the recombination of photogenerated electron–hole pairs. The {001} facets have an indirect role in the photocatalytic reduction of Cr(VI) because oxidative dissolution of H2O occurring on {001} facets and Cr(VI) reduction occurring on {101} facets are simultaneous reactions. The optimal ratio of exposed {001} to {101} was found to be ∼72:18.
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JOURNAL OF THE ELECTROCHEMICAL SOCIETY
·
2014
·Vol. 161
·期 9
·H573
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IF 2.859
Yong Kong,Ting Zhou,Yong Qin,Yongxin Tao,Yong Wei
Graphene plays a decisive role in the electrocatalytic copolymerization of aniline and m-aminophenol. The electrochemical activity of the obtained copolymer has an improved pH dependence compared with polyaniline. The results of Fourier transform infrared spectroscopy, electrochemical quartz crystal microbalance, atomic force microscope, and ultraviolet-visible spectroscopy reveal the ion exchange behaviors of the copolymer, indicating that it could be a potential candidate for the effective electrochemical removal of toxic Cr(VI) from industrial wastewater.
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Journal of Environmental Sciences
·
2014
·
IF 1.922
Wei Yao,Pinhua Rao,Irene M.C. Lo,Wenqi Zhang,Wenrui Zheng
Pollutants that exist in anionic species are issues of concern in water treatment . Compared to cationic pollutants, the removal of anionic pollutants by adsorption is more difficult because most adsorbents carry predominantly negative charges in neutral and alkaline environments . In this study, a cross-linked chitosan derivative with quaternary ammonium and magnetic properties (QM-chitosan) was prepared and employed to remove chromium(VI) and phosphorus(V) (Cr(VI) and P(V)) from aqueous environments. The QM-chitosan was characterized by Fourier transform infrared spectrometry (FT-IR), thermogravimetric analysis (TGA), energy dispersive X-ray (SEM-EDX) and zeta potential . Batch experiments show that QM-chitosan can effectively remove Cr(VI) and P(V), and the main mechanism was believed to be electrostatic interaction. A pseudosecond-order model was fitted to describe the kinetic processes of Cr(VI) and P(V) removal. The adsorption isotherms of both Cr(VI) and P(V) on the QM-chitosan were well fitted by the Langmuir isotherm equation. The saturated adsorption capacity of P(V) (2.783 mmol/g) was found to be higher than that of Cr(VI) (2.323 mmol/g), resulting from the size of the H 2 PO 4 − ions being smaller than that of the HCrO 4 − ions. However, the theoretical calculation and experimental results showed that QM-chitosan had a stronger affinity for Cr(VI) than P(V). The adsorption–desorption of the QM-chitosan was evaluated, and high regeneration rates were demonstrated.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
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2013
·
IF 3.172
Guangfang Li,Fan Qin,Runming Wang,Shengqiang Xiao,Hongzhe Sun,Rong Chen
A facile microwave irradiation method has been successfully developed for the controllable fabrication of BiOX (X = Cl, Br, I) nanostructures in mannitol solution. The morphology and size of BiOX nanostructures could be readily tailored by adjusting the amount of halide, reaction precursor, and mannitol concentration. Mannitol molecule acts as both a capping agent and a cohesive agent in the formation of BiOX nanostructures. A possible two-stage formation mechanism was discussed based on the morphology evolution of BiOI nanostructures obtained in mannitol solution with different concentrations. The as-synthesized BiOX nanostructures exhibit much higher photocatalytic activities than that of commercial TiO 2 . In particular, flower-like BiOX hierarchical nanostructures display the best photocatalytic performance, which is mainly ascribed to their unique hierarchical structure, high BET surface area, and large band gap. Moreover, BiOX nanostructures also demonstrate superior Cr(VI) removal capacity. The Cr(VI) adsorption behavior was also analyzed by the Langmuir and Freundlich adsorption isotherms.
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JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
·
2017
·
IF 3.154
Tiantian Luo,Xike Tian,Chao Yang,Wenjun Luo,Yulun Nie,Yanxin Wang
In this study, polyethylenimine-functionalized corn bract (PEI–CB) was first used to remove aqueous Cr(VI) via the “waste control by waste” concept. The results indicated that PEI–CB had an excellent performance for Cr(VI) removal and the maximum removal capacity was 438 mg/g. The adsorption of Cr(VI) was fitted to the Langmuir model, and kinetics of uptake could be described by a pseudo-second-order rate model well. Amine was proven to be the active center for Cr(VI) adsorption and partial reduction to Cr(III), while removal efficiency was enhanced at a lower pH value and higher temperature. Besides, nanosized Cr2O3 with a high purity was obtained by simple calcination of a Cr(VI)-laden adsorbent. Hence, this study provided a novel strategy for Cr(VI) wastewater remediation and pure Cr2O3 recovery. Prepared PEI–CB was then a promising alternative of low cost for replacement of the current expensive absorbent of removing Cr(VI) from wastewater from the view of sustainability.
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JOURNAL OF ENVIRONMENTAL MANAGEMENT
·
2024
·
IF 8
Yuhang Yang,Bing Li,Mingxi Li,Zhiyi Deng,Zuoyi Chen,Jinhua Wu
Zero-valent iron (Fe 0 ) usually suffers from organic acid complexation and ferrochrome layer passivation in Cr(VI) removal from bioleached wastewater of Cr slag. In this work, a synergetic system combined Fe 0 and mixed hetero/autotrophic bacteria was established to reduce and stabilize Cr(VI) from bioleached wastewater. Due to bacterial consumption of organic acid and hydrogen, severe iron corrosion and structured-Fe(II) mineral generation (e.g., magnetite and green rust) occurred on biotic Fe 0 surface in terms of solid-phase characterization, which was crucial for Cr(VI) adsorption and reduction. Therefore, compared with the abiotic Fe 0 system, this integrated system exhibited a 6.1-fold increase in Cr(VI) removal, with heterotrophic reduction contributing 3.4-fold and abiotic part promoted by hydrogen-autotrophic bacteria enhancing 2.7-fold. After reaction, the Cr valence distribution and X-ray photoelectron spectroscopy indicated that most Cr(VI) was converted into immobilized products such as Fe x Cr 1-x (OH) 3 , Cr 2 O 3 , and FeCr 2 O 4 by biotic Fe 0 . Reoxidation experiment revealed that these products exhibited superior stability to the immobilized products generated by Fe 0 or bacteria. Additionally, organic acid concentration and Fe 0 dosage showed significantly positive correlation with Cr(VI) removal within the range of biological adaptation, which emphasized that heterotrophic and autotrophic bacteria acted essential roles in Cr(VI) removal. This work highlighted the enhanced effect of heterotrophic and autotrophic activities on Cr(VI) reduction and stabilization by Fe 0 and offered a promising approach for bioleached wastewater treatment .
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2024
·
IF 9.4
Zhenyang Song,Yuting Xu,Mengyuan Zhang,Wei Zhu,Xudong Yang,Di Hao,Qing Li
Hypothesis Hexavalent chromium, recognized as one of the most toxic heavy metals, demands the development of advanced materials capable of both adsorption and photocatalysis for effective Cr (VI) removal. Experiments This study successfully synthesized a two-dimensional zinc porphyrin covalent organic framework (ZnPor-COF) via a solvent-based method. Performance evaluations have demonstrated that the ZnPor-COF possesses outstanding capabilities for the adsorptive and/or photocatalytic elimination of Cr (VI). Particularly noteworthy is the observation that when adsorption and photocatalysis are coupled, the ZnPor-COF attains an exceptional 99.7 % removal rate for a Cr (VI) concentration of 30 mg/L within just 60 min, with minimal susceptibility to coexisting ions. After five consecutive cycles, the material sustains a removal efficiency of 90 %, indicative of its robust cyclability. Findings Theoretical calculations, as well as experimental validations, have indicated that the integration of Zn ions into the porphyrin COF not only results in an expanded specific surface area and an increased count of adsorption sites but also significantly improves the COF’s photosensitivity and the capability for charge carrier separation. Furthermore, the core of the synergistic effect between adsorption and photocatalysis lies in the ability of photocatalysis to substantially augment the adsorption process.
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Processes
·
2025
·Vol. 13
·期 1
·156
·
IF 2.8
Ting Guan,Liang Fang,Fang Wu,Yongxia Yang
NiFe-layered double hydroxide (NiFe-LDH) and La-, Mo- or W-doped NiFe-LDH microparticles (NiFeX-LDH, X = La, Mo, W) were synthesized via the co-precipitation method. Their adsorption characteristics were evaluated by the removal of methyl orange (MO) and hexavalent chromium (Cr6+). The effects of the metal ion doping type, doping concentration (0–3at%), pH and temperature on the MO adsorption properties were systematically studied. The results show that W-doped NiFe-LDH exhibits superior MO removal capacity compared to undoped or La- or Mo-doped NiFe-LDH at the same 1at% doping level, which is attributed to the increased layer charge density and strong affinity for the π-electron systems of MO molecules. The NiFeW-LDH-1at% sample demonstrated the best MO adsorption performance within the W-doping range of 0–3at%, achieving a superior adsorption capability of 666.67 mg/g with a significantly shorter equilibrium time (10–120 min) compared to the similar LDH. NiFeW-LDH-1at% showed promising reusability, with its adsorption efficiency remaining 78.3% of its initial level after five adsorption–desorption cycles. The MO uptake onto NiFeX-LDH was attributed to the combined effect of anion exchange and the attraction of layer charge. In addition, the adsorption of NiFeW-LDH-1at% matched well with the Langmuir isotherm model and pseudo-second-order kinetic model, indicating a monolayer and chemical adsorption. Furthermore, NiFeW-LDH-1at% effectively adsorbed of Cr2O72−in the aqueous solution, revealing that W doping significantly enhances Cr(VI) removal performance. The maximum theoretical adsorption capacity onto NiFeW-LDH-1at% reached 63.25 mg/g, which was notably higher than that of the pristine NiFe-LDH adsorbent (53.56 mg/g). Overall, the W-doped NiFe-LDH material, as a low-cost and highly efficient adsorbent, shows great potential for wastewater treatment application.
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