JOURNAL OF COLLOID AND INTERFACE SCIENCE
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2022
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IF 9.965
Chenrui Liu,He Xiao,Yun Liu,Dejian Li,Hao He,Xiaohan Huang,Wentao Shen,Zhiyan Yan,Zhi Dang,Runliang Zhu
Improving the separation efficiency and transfer ability of photoinduced electrons/holes in pyrite (FeS 2 )-based photocatalytic materials is significant for the photoreduction of hexavalent chromium (Cr(VI)) but still remains a challenge. Herein, a novel homojunction was prepared through in-situ growth of nickel (Ni) doped FeS 2 nanoparticles on FeS 2 nanobelts (denoted as Ni-FeS 2 /FeS 2 ). Systematical characterizations revealed that Ni doped FeS 2 nanoparticles have been successfully in situ grown along the lattice of FeS 2 nanobelts . Photoreduction experiments demonstrated that the Ni-FeS 2 /FeS 2 homojunction with 2 mmol Ni doping contents (denoted as 2Ni-FeS 2 /FeS 2 ) exhibited the optimum Cr(VI) reduction efficiency among the studied catalysts. Density Functional Theory (DFT) calculated results verified that Ni doping could not only be advantageous for the formation of sulfur vacancies but also modify the band gap and band structure of FeS 2 nanoparticles . Moreover, several doping energy levels caused by Ni doping have also appeared near the Fermi level of FeS 2 nanoparticles . The migration paths of electrons and the existence of internal electric field (IEF) in homojunction were further verified by the calculation of work function . To sum up, the doping energy levels and IEF that produced by homojunction played important roles in accelerating the separation efficiency of its photogenerated carriers.
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SEPARATION AND PURIFICATION TECHNOLOGY
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2022
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IF 9.136
Lili Zhang,Bihui An,Haojie Chen,Jingjing Chu,Jinxia Ma,Yimin Fan,Zhiguo Wang
Catalytic membrane technology, as a combination of membrane separation and catalysis, is a high-efficiency and feasible route for wastewater remediation. The controllable synthesis of ultrasmall metal nanoparticles on the membrane to maximize the size effect is a challenging task yet. Herein, the filter paper-based botryoidal nanolignin channel stabilized ultrasmall PdNP membrane (Pd@LNP/FP) was prepared by chemical crosslinking of epichlorohydrin (EPI), the nanolignin (LNP) serves as both reducing and capping agent for the in-situ synthesis of ultrasmall PdNP with enhanced active sites. The mean size of PdNP was effectively tuned from 1.76 to 2.09 nm by varying the LNP loading amount of composite membranes. The botryoidal LNP supported on FP also provides the nanoscale channel to keep reactants on active sites of ultrasmall PdNP to improve the catalytic performance of Pd@LNP E /FP. The complete removal of hazardous Cr(VI) required only 2.5 min using Pd@LNP E /FP membrane, the pseudo-first-order rate constant (k) is 1.2725 min −1 , much higher than that of the Pd@LNP p /FP membrane prepared by physical composite (0.2885 min −1 ). Moreover, the rapid filtration-catalysis removal of Cr(VI) can be achieved by twice filtration, demonstrating the high efficiency and feasibility of Pd@LNP E /FP via synergetic filtration enrichment and catalysis reduction.
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COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
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2022
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IF 5.518
Jun Liu,Hui Wang,Meng-Jie Chang,Meng Sun,Zhi-Wei He,Cong-Miao Zhang,Wen-Yao Zhu,Jia-Liang Chen,Hui-Ling Du,Long-Gui Peng,Zhen-Min Luo,Li Zhang
Magnetically separatable CoFe 2 O 4 /BiOCl (CFO/BOC) fibers were facilely prepared by solvothermal growth of BiOCl on hollow electrospun CoFe 2 O 4 nanofibers in a weak reduction ethylene glycol (EG) solvent for visible light photocatalytic degradation of various contaminants. Due to the defect level resulted from the oxygen vacancies (OVs), evident visible light response and enhanced charge transfer are achieved both for the solo BiOCl spheres and nanosheets on the CoFe 2 O 4 fibrous support. The optimum CFO/BOC synthesized at 160 °C with a precursor concentration of 50 mM shows outstanding photocatalytic activity to degrade different pollutants of Rhodamine B (RhB, 92.9%), Norfloxacin (NOR, 75.5%), and Cr(VI) (78.0%) within 2 h under visible light. The CoFe 2 O 4 nanofibers are not pivotal for the photocatalytic process, but mainly contribute to the photocatalysis as magnetic support, ensuring the CFO/BOC no aggregation and easy collection under an external magnet. In contrast, the OVs play an important role in the visible light absorption , reactive oxygen species generation and redox process during the photocatalytic process. In detail, both photosensitization of RhB and species of h + and·O 2 - contribute to the degradation of RhB, while NOR decomposition is accomplished by three species (h + ,·O 2 - ,·OH). In addition, electrons are the main reactive species for the photoreduction of Cr(VI). Compared to current reported CoFe 2 O 4 /BiOI photocatalysts , significant advances for the CFO/BOC are obtained not only for the cheap BiOCl with OVs for the photocatalytic application, but also much clearer investigation of more details of CFO/BOC photocatalysts such as light absorption, charge transfer and active species for the degradation of various pollutants.
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SCIENCE OF THE TOTAL ENVIRONMENT
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2022
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IF 10.753
Peiling Han,Jiayin Xie,Xueming Qin,Xinru Yang,Yongsheng Zhao
Micron zero valent iron (mZVI) was an underground remediation material, which had great application potential to replace nano zero valent iron (nZVI) from the perspective of economic and health benefits. However, mZVI was highly prone to gravitational settling, which limited its wide application for in situ remediation of contaminated groundwater. This paper was devoted to develop an efficient and economical groundwater remediation material based on mZVI, which should possess excellent stability, reactivity, and transportability. Thereby xanthan gum (XG) stabilized and Na 2 S 2 O 4 sulfidated mZVI (XG-S-mZVI) was synthesized and characterized with SEM, XRD , XPS , and FTIR techniques. In terms of stability, the adsorbed XG and the dispersed XG worked together to resist the sedimentation of S-mZVI. In terms of reactivity, sulfidation enhanced the electron transfer rate and electron selectivity of XG-S-mZVI, thereby improved the reactivity of XG-S-mZVI. The hexavalent chromium (Cr(VI)) removal rate constant by XG-S-mZVI was determined to be 832.4 times than bare mZVI. In terms of transportability, the transportability of XG-S-mZVI was greatly improved (~80 cm in coarse sand and ~50 cm in medium sand). Straining was the main mechanism of XG-S-mZVI retention in porous media . XG-S-mZVI in situ reactive zone (XG-S-mZVI-IRZ) was only suitable to the media with a grain size larger than 0.25 mm. This study could provide theoretical support and guidance for the implementation of IRZ technology based on mZVI.
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JOURNAL OF HAZARDOUS MATERIALS
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2021
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IF 10.588
Hao Wang,Shuai Wang,Shixing Wang,Jiali Tang,Yingbi Chen,Libo Zhang
A new zirconium-based adsorption material (UiO-66-AMP) was prepared by modifying UiO-66-NH 2 with 5-adenosine to effectively remove Pb(II) and Cr(VI) from wastewater. The SEM, EDS, XRS and FT-IR characterization confirmed the successful synthesis of UiO-66-AMP. We conducted a sets of experiments to test the adsorption effectiveness of UiO-66-AMP for Pb(II) and Cr(VI). The maximum adsorption capacity of UiO-66-AMP for Cr(VI) (pH=2) and Pb(II) (pH=4) are 196.60 and 189.69 mg/g, respectively. The adsorption process conforms to the pseudo-second-order and Langmuir models, which indicates that the adsorption is a single-layer chemical process. Gibbs free energy ( ∆G) indicates that the adsorption of Pb(II) is an exothermic reaction , while the adsorption of Cr(VI) is an endothermic reaction . At the same time, the adsorbent maintains excellent adsorption capacity at least after 4 cycles. The good adsorption performance of UiO-66-AMP towards the metal ions was attributed to the surface complexation and electrostatic interactions. Therefore, the new adsorbent has obvious application prospect to remove Pb(II) and Cr(VI) from wastewater.
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Journal of Environmental Chemical Engineering
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2023
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IF 7.7
Peng Cheng,Zhiyang Wei,Yara Arbid,Tengfei Fu,Xiaowei Liu,Olivier Monfort
The primary aim of this work is to test a novel adsorbent prepared by cross-linking of tetrafluoroterephthalonitrile with chitosan (CS-TFT) for the removal of Cr(VI) and U(VI). The CS-TFT is stable until 250 °C and possesses amino functional groups due to the presence of CS that remain intact even after the cross-linking reaction, thus being a benefit for adsorption properties; while the TFT brought roughness to CS-TFT that keeps its high porosity. The adsorption efficiency of CS-TFT is evaluated in the batch experiment of Cr(VI) and U(VI) adsorption along with the effect of different experimental parameters (pH, time, temperature, initial concentrations, and co-existing inorganic cations). The maximum adsorption capacity of CS-TFT for adsorption of Cr(VI) and U(VI) was 265.96 mg·g -1 at pH = 3 and 346.06 mg·g -1 at pH = 5, respectively, at 298 K and the corresponding partition coefficients were 12,454 and 6181 mg g -1 mM -1 , respectively. The kinetics of the adsorption process is identified as a pseudo-second-order model and the Langmuir isotherm model is considered. The CS-TFT shows satisfactory reusability since it can be used after 6 cycles of regeneration with a removal efficiency of Cr(VI) and U(VI) higher than 90 %. The adsorption mechanism is also proposed based on investigation of CS-TFT by FTIR, XPS and SEM-EDS before and after adsorption. The results show that hydroxy (–OH) and amino (–NH 2 ) groups play a key role in the chemical adsorption . All these findings suggest that CS-TFT could be a promising adsorbent for wastewaters treatment .
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JOURNAL OF ALLOYS AND COMPOUNDS
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2023
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IF 6.2
Kai Xuan,Taiguang Li,Yongmei Hao
The photo-Fenton system degrades pollutants, which can not only take the advantages of photocatalysis and Fenton reaction, but also avoid the drawbacks of each. However, removing pollutants without the addition of hydrogen peroxide (H 2 O 2 ) in photo-Fenton systems is still a challenge. Therefore, it is an outstanding strategy that inner-generate H 2 O 2 can provide more hydroxyl radicals to enhance the degradation of pollutants. This study reports a ZnIn 2 S 4 /Fe-POMs photo-Fenton system capable of degrading environmental pollutants due to the reaction between inner-generate H 2 O 2 (0.0248 mM in 15 min) and the stable circulation of Fe 3+ /Fe 2+ . As a result, the photodegradation efficiency of carbamazepine by ZnIn 2 S 4 /Fe-POMs can reach 93.92% within 60 min simulated solar irradiation even under neutral conditions. In addition, ZnIn 2 S 4 /Fe-POMs can remove Cr (VI) completely within 10 min under visible light irradiation. This work not only experimentally verifies the inner-generate H 2 O 2 can accelerate the Fe 3+ /Fe 2+ conversion, but also broadens the initial pH range (pH=3–9) for constructing efficient photo-Fenton systems.
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Nanomaterials
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2023
·Vol. 13
·期 20
·2745
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IF 5.3
Jing Li,Mingjie Fan,Ziting Yuan,Fang Liu,Miao Li
Hexavalent chromium (Cr(VI)) is a typical heavy metal pollutant, making its removal from wastewater imperative. Although nanosized zero-valent iron (nZVI) and graphene-based materials are excellent remediation materials, they have drawbacks, such as agglomeration and being difficult to recycle. A facile synthesis method for decorating reduced graphene oxide (rGO) with ultrathin nZVI (within 10 nm) was explored in this study in order to develop an effective tool for Cr(VI) detoxication. Cu particles were doped in these composites for electron-transfer enhancement and were verified to improve the rate by 2.4~3.4 times. Batch experiments were conducted at different pHs, initial concentrations, ionic strengths, and humic acid (HA) concentrations. From these observations, it was found that the acid condition and appearance of Cu and rGO enhanced the treatment capacity. This procedure was fitted with a pseudo-second-order model, and the existence of NaCl and HA impeded it to some extent. Cr(VI) could be detoxified into Cr(III) and precipitated on the surface. Combining these analyses, a kinetics study, and the characterizations before and after the reaction, the removal mechanism of Cr(VI) was further discussed as a complex process involving adsorption, reduction, and precipitation. The maximum removal capacity of 156.25 mg g−1occurred in the acid condition, providing a potential Cr(VI) remediation method.Keywords:nano zero-valent iron (nZVI);reduced graphene oxide (rGO);Cu doping;hexavalent chromium (Cr(VI));removal
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JOURNAL OF MOLECULAR STRUCTURE
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2021
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IF 3.196
Congcong Piao,Jianhe Tang,Yitong Lin,Zhiyu Liu,Xueke Liu,Dawei Fang,Jun Wang
A high-efficiency Z-scheme photocatalyst, Er 3+ :YAlO 3 @(Au/SrTiO 3 )-Au-WO 3 , is fabricated successfully via hydrothermal and photo-deposition methods. All as-prepared samples are characterized by XRD, SEM, TEM, FT-IR, EDX, XPS, Raman spectroscopy, PL and DRS. The activity of the prepared Z-scheme Er 3+ :YAlO 3 @(Au/SrTiO 3 )-Au-WO 3 photocatalyst is evaluated through photocatalytic conversion of Cr(VI) under simulated solar light irradiation. The meaningful influencing factors such as simulated solar light irradiation time, light intensity, sacrificial agents and cycling times are investigated. The results displayed that the existence of Er 3+ :YAlO 3 can improve the utilization ratio of solar light for wide band-gap SrTiO 3 . Moreover, the formation of Z-scheme SrTiO 3 /WO 3 photocatalytic system and the introduction of Au nanoparticles as electron mediator and co-catalyst can promote the separation of photo-induced electron and hole to obtain much high photocatalytic activity . Finally, the mechanism on conversion of Cr(VI) caused by Z-scheme Er 3+ :YAlO 3 @(Au/SrTiO 3 )-Au-WO 3 photocatalyst is put forward. © 2021 Elsevier B.V. All rights reserved.
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SEPARATION AND PURIFICATION TECHNOLOGY
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2021
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IF 7.312
Ousmanou Njoya,Shengxin Zhao,Xingyu Kong,Jimin Shen,Jing Kang,Binyuan Wang,Zhonglin Chen
The treatment of industrial wastewater containing Cr(VI)–organic compounds is a long-term concern in the field of environment. In order to realize the high-efficient reduction of Cr(VI) and solve the problem of Cr(III) residue in water environment, a novel catalytic chemical reduction/membrane filtration method was developed for the removal of total Cr (TCr) in a system with coexisting Cr(VI) and oxalate (Ox). The effects of the concentrations of Ox, Fe(III), and Al(III), the dosage of NaBH 4 , and sedimentation time on the removal of Cr(VI) containing Ox by NaBH 4 were investigated. Additionally, the simultaneous removal of turbidity and TCr using a microfiltration membrane was investigated, and the reason for the enhanced TCr removal was clarified. The results of ion chromatography (IC), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) suggested that when Cr(VI) and Ox coexist, low concentrations (0.3 mM) of Fe(III) or Al(III) contributed significantly to the high turbidity caused by the formation of suspended solids (SS) following the reduction of Cr(VI) by NaBH 4 . However, almost all the Cr(III) could be removed by a 1-μm microfiltration membrane. The high turbidity system formed by Ox and Cr(III) is unstable, and some Ox will gradually release their binding sites with Cr(III) with the extension of the natural settling time. For 24 h, 53.75% of Ox was involved in the formation of SS, while in the presence of Fe(III) or Al(III), only 11.28% and 6.30% of Ox were involved, respectively. High concentrations of Fe(III) and Al(III) enhanced the reduction of Cr(VI) by NaBH 4 . The removal of TCr was close to 100% after natural sedimentation for 15 min and combined with a microfiltration membrane. This result is caused because Fe(III)–Cr(III) or Al(III)–Cr(III) can form larger SS, which is easily intercepted by the microfiltration membrane. The development of a novel combined method of catalytic chemical reduction and membrane filtration will be beneficial for reducing the retention of TCr in the environment.
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CHEMOSPHERE
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2020
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IF 5.778
Xuefeng Liu,Guoshuai Liu,Shijie You
Advanced reduction process (ARP) has drawn an increasing interest as a new manner for removing oxidative pollutants in water. In this paper, we demonstrate the possibility of in-situ reduction of Cr(VI) by CO 2 ·- produced from formate originally existing in leather wastewater by visible-light-driven ARP containing black TiO 2 photocatalyst. The prepared black TiO 2 with nanotube structure achieves remarkable enhanced the reduction rate of Cr(VI) as high as 96.2% (k = 0.0114 min −1 ) in the presence of formate, which is approximately 4.75 times than that of 56.3% (k = 0.0024 min −1 ) in the absence under 120 min visible-light irradiate at unadjusted pH. The results exhibit a distinct contrast with commercial TiO 2 (P25). A series of control experiments are also performed, indicating that formate is able to convert the oxidative environment into a highly reductive one, and the formate concentration, black TiO 2 dosage and pH may greatly impact on the Cr(VI) reduction rate. According to the electron spin resonance (ESR) measurement, CO 2 ·- radicals can be directly verified as dominate radical in this system. Moreover, this system appears to be attractive for creating photochemical systems where in-situ production of CO 2 ·- radicals may be realized by using formate. Then this in-situ ARP system will provide a new perspective for the Cr(VI) removing, which makes leather wastewater treatment much easier and more sustainable in the future.
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CARBOHYDRATE POLYMERS
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2020
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IF 7.182
Yixing Duan,Jisuan Tan,Zeming Huang,Qiaomei Deng,Sijia Liu,Guan Wang,Ligui Li,Li Zhou
Nowadays the synthesis of stable fluorescent sulfur quantum dots (SQDs) remains a big challenge. Herein, the utilization of carboxymethyl cellulose (CMC) to synthesis of SQDs is reported. Benefiting from the unique composition and structure of CMC macromolecule, the resulted CMC-SQDs simultaneously show high aqueous dispersibility and stability, tunable emission, stable fluorescence and low cytotoxicity, which make them promising for working as a fluorescent probe. Fluorescence detection experiments suggested that the CMC-SQDs could serve as a fluorescence on-off-on switch to sensitive and selective detection of Cr(VI) and ascorbic acid (AA) based on the inner filter effect (IFE). The limit of detection towards Cr(VI) and AA can reach 0.024 and 0.18 μM with linear range of 0.5−225 and 1−300 μM, respectively, which compares favorably to other reported fluorescent probes. In addition, the employment of fluorescent CMC-SQDs for practical detection of Cr(VI) and AA was also studied.
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