SEPARATION AND PURIFICATION TECHNOLOGY
·
2022
·
IF 9.136
Hao Du,Ningyi Li,Lingxuan Yang,Qiang Li,Guoxiang Yang,Qi Wang
Environmental crisis caused by Cr(VI) pollution has gained remarkable attention. Developing efficient photocatalysts for Cr(VI) remediation remains a great challenge. Herein, the Ag@Ag 3 VO 4 /Ag 3 PMo 12 O 40 (Ag@Ag 3 VO 4 /AgPMo) S-scheme heterojunctions were prepared via the combination of hydrothermal and photodeposition methods for Cr(VI) reduction. The resultant S-scheme heterojunctions were characterized to investigate their morphological, structural, photoelectrochemical and optical properties. The synergy of surface plasmon resonance (SPR) effect of Ag and S-scheme hetero-structure improved their photo(electro)chemical performance. Upon visible light irradiation, the optimized Ag@Ag 3 VO 4 /AgPMo delivered superior photoreduction efficiency (94.8%) of Cr(VI) and stability with a slight loss of the performance (92.8% after 6 cycles). The enhancement of Cr(VI) reduction performance may be ascribed to the extended light absorption range and separation and migration pathway of photo-induced electron-hole pairs confirmed by the proposed photoreduction mechanism. This work not only confirms a highly active catalytic system for the light-driven environmental application, but pave a way for the construction of S-scheme heterojunction photocatalysts.
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Gels
·
2022
·Vol. 8
·期 9
·546
·
IF 4.432
Xiaolei Ma,Duomo Duan,Jinbin Chen,Baolong Xie
Hydrogels with polysaccharides as high polymer substrates have surprising advantages in wastewater treatment with complex components. Therefore, in this study, polysaccharides named EPS were extracted fromEnteromorpha prolifera, a coastal pollutant with a wide range of sources, and cationic modification was performed to obtain CAEPS, the hydrogel with a double network structure was prepared based on EPS and CAEPS. Meanwhile, the structural characteristic of EPS and CAEPS-based hydrogel were identified by HPLC, AFM, FT-IR, TGA, SEM-EDS, Pore size distribution, and WCA, which showed that the porosity, apparent (skeletal) density, and hydrophilicity of CAEPS-hydrogels. We used nonlinear isotherms to uncover the adsorption mechanism of hydrogel applied to the water environment containing three typical pollutants (Methylene blue, Cefuroxime, and Cr (VI)). The results showed that the adsorption isotherm of the two hydrogels fit the Langmuir isotherm model, which indicated the monolayer adsorption of the pollution factor onto EPS- and CAEPS-hydrogels. The maximum adsorption capacities of CAEPS-hydrogels were higher than EPS-hydrogels, which indicated the microstructure and adsorption performance of the CAEPS-hydrogel are strengthened.Keywords:cationic enteromorpha polysaccharide;hydrogel;structural;adsorption
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2022
·
IF 9.136
Jianhao Qiu,Dingliang Dai,Lu Zhang,Guanglu Xia,Jianfeng Yao
Oxygen vacancy-rich Bi 2 MoO 6 nanoflakes were uniformly anchored on cuboid MIL-121 via benign solvothermal and thermal-reduction methods. Benefiting from the efficient light capture and rich electron traps triggered by oxygen vacancies, intimate interface contact and intrinsic heterostructure, the enhanced separation and transportation rates of photo-induced charge carriers are achieved. Consequently, Bi 2 MoO 6 /MIL-121 with rich oxygen vacancies performs excellent photocatalytic activities, which are 4.8, 7.1, 1.4 times higher for Cr(VI) reduction, and 6.1, 5.4, 1.2 times higher for 2-nitrophenol degradation compared with those of Bi 2 MoO 6 , MIL-121 and Bi 2 MoO 6 /MIL-121 without oxygen-vacancies, respectively. Furthermore, thanks to the timely consumption of photo-induced electrons and holes by Cr(VI) reduction and 2-nitrophenol degradation, respectively, the corresponding photocatalytic efficiencies are further boosted in their coexistent environment. This work would enlighten the design of metal-organic framework-based (photo)catalysts for the treatment of complicated pollution.
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JOURNAL OF HAZARDOUS MATERIALS
·
2021
·
IF 10.588
Yibo Yuan,Xipeng Wei,Hua Yin,Minghan Zhu,Haoyu Luo,Zhi Dang
The effects of organic acids on hexavalent chromium (Cr(VI)) removal by reduced iron-based materials have been extensively studied. Nevertheless, the promotion mechanism from the perspective of the electron transfer process is still unclear. Herein, sulfidated nanoscale zero-valent iron (S-nZVI) and the selected organic acids, citric acid (containing both -OH and −COOH groups) and oxalic acid (containing only −COOH groups), showed significant synergistic promotion effects in Cr(VI) removal. The FeS and FeS 2 on S-nZVI surface could enhance the Cr(VI) reduction as the reductive entity and electron conductor. Furthermore, even though the reactivity of FeS with Cr(VI) is higher than that with FeS 2 , the Cr(VI) removal efficiency by FeS 2 was much higher than that by FeS with organic acids. Under neutral and alkaline conditions (pH 6.0–8.0), organic acids promoted the diffusion, adsorption and complexation of Cr(VI) on S-nZVI surface, thus enhancing the electron selectivity towards Cr(VI). However, when the solution pH changed to acidic conditions (pH 4.0), organic acids facilitated the dissolution of Fe(II) ions from S-nZVI and enhanced the electron utilization towards Cr(VI) via the fast Fe(III) reduction process. This study provided a new insight into the Cr(VI) removal, which was beneficial to understand the application boundaries of S-nZVI for Cr(VI) remediation.
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JOURNAL OF MEMBRANE SCIENCE
·
2021
·
IF 8.742
Wen-Han Yu,Zhi-Qiang Gan,Jia-Rong Wang,Yu Zhao,Jun Han,Li-Feng Fang,Xiu-Zhen Wei,Ze-Lin Qiu,Bao-Ku Zhu
Nanofiltration (NF) membrane has an extensive application in the field of water treatment, but weakly negative surface-charge and even charge inversion in acidic environment restrict wide applications of traditional aromatic polyamide (PA) thin film composite (TFC) NF membrane in a broad pH range. In this work, 4, 4′-diaminostilbene-2, 2′-disulfonic acid (DSDA), a novel acidic aqueous monomer , was introduced into interfacial polymerization to fabricate a TFC NF membrane with enhanced negative charge and pH stability. The effects of interfacial polymerization parameters were investigated to improve membrane performance. The optimal membrane exhibits a pure water permeance (PWP) of 10.0 ± 0.5 L m −2 h −1 ·bar −1 and a high Na 2 SO 4 rejection (i.e., ~97.0%). The resultant membrane remains a strongly negative charge when the pH value is changed from 2 to 12. Due to enhanced negative charge, Donnan exclusion plays a significant role in membrane separation process, which results in a huge superiority in removal of Na 2 SO 4 , Na 3 PO 4 and K 2 Cr 2 O 7 in a broad pH range especially in acidic environment. Hence, it is demonstrated that the negative-charged NF membrane prepared in this work has improved and stable separation performance under a broad pH range, which expands application scopes of NF membrane, especially in removing Cr (VI) and phosphate in acidic environments. Besides, this study also provides a feasible route for preparation of suitable TFC NF membrane for working in acidic environment via introducing strongly acidic groups in selective layer.
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COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
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2021
·
IF 4.539
Yang Chen,Huijing Cui,Mao Wang,Xudong Yang,Shujie Pang
Cr(VI) is a toxic heavy metal, which is not readily decomposed and ingested by bacteria. Therefore, there is an urgent need for a sensing method with high selectivity and high sensitivity to detect Cr(VI) in other widely distributed metal ions . Here, a fluorescent probe based on carbon dots (CDs) was developed, with the characteristics of low cost, low environmental impact, high stability, and good water solubility. Although many sensors have been reported for the detection of Cr(VI), most of them are based on the quenching fluorescence method , whereas the one reported here is based on fluorescence enhancement, for which o-phenylenediamine and dl -Thioctic acid were used as raw materials. The transmission electron microscopy , Fourier infrared spectroscopy , X-ray photoelectron spectroscopy, X-ray diffraction, and ultraviolet-visible spectroscopy measurements showed that Cr(VI) can significantly enhance the fluorescence of the probe compared to previous sensors, as the obtained CDs have excellent fluorescence properties (quantum yield up to 21.82%) and high light stability. The detection limit of the probe for Cr(VI) is as low as 0.64 μM, indicating that the developed probe can detect Cr(VI) quickly, sensitively, and selectively, and has broad application prospects in environmental analysis applications. To facilitate rapid detection of Cr(VI), the CDs were also incorporated into a fluorescent composite film suitable for visual inspection.
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JOURNAL OF HAZARDOUS MATERIALS
·
2021
·
IF 10.588
Yangzi Shangguan,Renji Zheng,Qiuyue Ge,Xuezhen Feng,Ranhao Wang,Yuanhao Zhou,Siyuan Luo,Lele Duan,Jia Lin,Hong Chen
Configuring reactive and stable catalytic interfaces is crucial to design efficient photocatalysts for Cr(VI) reduction. Herein, via the platinum decoration approach based on interfacial engineering , we developed an effective catalytic interface within novel semiconducting chalcopyrite quantum dots (Pt/CuFeS 2 QDs). Benefiting from the catalytic merits of the Pt modulated interfacial structure and electronic structure, Pt/CuFeS 2 QDs show a broader light absorption capability extending to near-infrared radiation (NIR) range with superior carriers separation performance and faster charge transfer efficiency, which delivers a three-folder faster photocatalytic Cr(VI) reduction efficiency comparing to the original CuFeS 2 QDs. Density functional theory (DFT) calculations unravel that Pt atoms prefer to be anchored with the surface S atoms to form a stable interfacial structure with faster electron transfer and Cr(VI) reduction dynamics. This work demonstrates that platinum decoration based on interfacial engineering is an effective strategy to simultaneously modulate the band structure and accelerate the interfacial reaction dynamics for semiconductor photocatalysts, which paves the way for designing highly efficient photocatalysts for light-driven environmental and energy engineering applications.
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Journal of Environmental Sciences
·
2020
·
IF 4.302
Kai Liu,Fangbai Li,Qingwen Tian,Chengrong Nie,Yibing Ma,Zhenlong Zhu,Liping Fang,Yuanying Huang,Siwen Liu
Paddy soil and irrigation water are commonly contaminated with hexavalent chromium [Cr(VI)] near urban industrial areas, thereby threatening the safety of agricultural products and human health. In this study, we develop a porous and high specific area bone char (BC) to support nanoscale zero-valent iron (nZVI) and apply it to remediate Cr(VI) pollution in water and paddy soil under anaerobic conditions. The batch experiments reveal that BC/nZVI exhibits a higher removal capacity of 516.7 mg/(g•nZVI) for Cr(VI) than nZVI when normalized to the actual nZVI content, which is 2.8 times that of nZVI; moreover, the highest nZVI utilization is the nZVI loading of 15% (BC/nZVI15). The Cr(VI) removal efficiency of BC/nZVI15 decreases with increasing pH (4 – 10). Coexisting ions (phosphate and carbonate) and humic acid can inhibit the removal of Cr(VI) with BC/nZVI15. Additionally, BC exhibits a strong advantage in promoting Cr(VI) removal by nZVI compared to the widely used biochar and activated carbon. Our results demonstrate that reduction and coprecipitation are the dominant Cr(VI) removal mechanisms. Furthermore, BC/nZVI15 shows a significantly higher reduction and removal efficiency as well as a strong anti-interference ability for Cr(VI) in paddy soil, as compared to nZVI. These findings provide a new effective material for remediating Cr(VI) pollution from water and soil.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2021
·
IF 7.312
Shifeng Zhao,Zhaosong Li,Haiyan Wang,Hanhan Huang,Caifeng Xia,Derui Liang,Junshan Yang,Qian Zhang,Zilin Meng
Mg-Al layered double hydroxides coated waste textile (MgAl-LDH@WT) was prepared by an in-suit method for the separation of toxic metal ions such as As(V) and Cr(VI) from soil samples. Kinetics studies of As(V)/Cr(VI) removal by MgAl-LDH@WT with different Mg/Al ratio were well described by intraparticle diffusion and pseudo-second-order model. Adsorption isotherm data of As(V)/Cr(VI) yielded a better accordance of Langmuir model, manifesting that accessible adsorption site was the main influence factor and the removal of As(V)/Cr(VI) was a charge-limited process. The adsorption capacity was 69.8 mg/g, 49.8 mg/g, 45.6 mg/g and 38.2 mg/g by Mg 2 Al-LDH@WT, Mg 3 Al-LDH@WT, Mg 4 Al-LDH@WT and LDHs, and for Cr(VI) were 27.5 mg/g, 24.9 mg/g, 19 mg/g and 6.8 mg/g, respectively. Adsorption behavior of As(V) and Cr(VI) co-existing in soil indicated that As(V) possess a preferential adsorption rather than Cr(VI) by Mg 2 Al-LDH@WT, and molecular simulation was selected to explain the results of competitive relationship by bonding energy and variation of bond length. The effect of co-existing ions, column leaching experiment and recycle experiment for practical performance assessment were also examined, and these results revealed a high stability and a good partition capability. The performance of excellent removal and convenient recovery suggested a promising strategy in anionic heavy metals contaminated soil.
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MICROCHIMICA ACTA
·
2021
·Vol. 188
·期 3
·1-12
·
IF 5.833
Yao Chixuan,Liu Qingrun,Zhao Ning,Liu Jing-Min,Fang Guozhen,Wang Shuo
A simple dual-colour fluorescent nanoprobe has been designed composed of blue and yellow emission carbon quantum dots (CQDs). This system is inexpensive and easy to operate and was successfully employed for on-site measurements based on a smartphone app. The designed nanoprobe exhibited increased selectivity for Cr(VI), leading to a double stable response of the two CQDs. The dual-emission nanoprobe showed blue-violet fluorescence upon UV irradiation, and the fluorescent emission peaks were located at 418 nm and 552 nm. The blue light emission of CQDs was quenched with increasing Cr(VI) concentration due to the inner filter effect, whereas the yellow light emission was enhanced due to the aggregation-induced emission effect. The different responses of the dual emissions to Cr(VI) resulted in a fluorescent colour variation, thus enabling facile macroscopic visualization. With a smartphone, the change in the fluorescence colour could be observed more apparently than that of a single fluorescence nanoprobe, and the response increased linearly so that the nanoprobe could be applied to instantaneous measurements. Furthermore, the dual-emission nanoprobe was successfully employed for analysing food and water samples. Accurate concentrations were obtained by constructing a calibration plot using a fluorescence spectrometer and a smartphone app; the recoveries were 81.6% to 107.7%, and the relative standard deviation was below 3.6%. Therefore, this smartphone-integrated dual-emission detection system is promising as a new portable method for the on-site measurement of Cr(VI) ions. Graphical abstract
* Y-CQDs: yellow emission carbon quantum dots. B-CQDs: blue emission carbon quantum dots. B/Y-CQDs: a mixture of B-CQDs and Y-CQDs.
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CHEMICAL ENGINEERING JOURNAL
·
2021
·
IF 13.273
Chen Wang,Chao Xiong,Yali He,Chen Yang,Xiteng Li,Jianzhong Zheng,Shixing Wang
A novel magnetic Zr-MOF named Ni 0.6 Fe 2.4 O 4 -UiO-66-PEI was synthesized by modifying UiO-66-NH 2 with Ni 0.6 Fe 2.4 O 4 and polyethyleneimine and its sorption characteristics for two representing heavy metals Pb(II) and Cr(VI) in water were examined. This material showed good thermal stability and was sufficiently magnetic to allow effective solid-liquid separation. The material had a maximum adsorption capacity of 273.2 mg/g for Pb(II) at pH 4.0 and 428.6 mg/g for Cr(VI) at pH 3.0, as obtained from the model fitting by the Hill equation. The sorption kinetics for both heavy metals on the material was fast, with adsorption equilibrium established in 60 min and 30 min for Pb(II) and Cr(VI), respectively. Model fitting of the kinetic data showed that Pb(II) and Cr(VI) sorption on Ni 0.6 Fe 2.4 O 4 -UiO-66-PEI followed the pseudo-second-order model. This material had good selectivity for competing ions, and still hold fairly good binding capacities after 5 times of regeneration. Adsorption mechanisms for Pb(II) and Cr(VI) by Ni 0.6 Fe 2.4 O 4 -UiO-66-PEI were proposed by analyzing FTIR, XPS and the electrokinetic property of the material. Specifically, Pb(II) adsorption on Ni 0.6 Fe 2.4 O 4 -UiO-66-PEI could be attributed to chelation of Pb(II) with the imine/amine functional groups in the material’s matrix, while Cr(VI) adsorption might stem from a combination of electrostatic attraction, chelation and redox reaction. It seems that Ni 0.6 Fe 2.4 O 4 -UiO-66-PEI could be used as a green and environmental-friendly material for heavy metals removal, particularly from acidic water streams.
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NEW JOURNAL OF CHEMISTRY
·
2020
·Vol. 44
·期 18
·7611-7620
·
IF 3.288
Phung Nhat Minh,Van-Tuan Hoang,Ngo Xuan Dinh,Ong Van Hoang,Nguyen Van Cuong,Dang Thi Bich Hop,Tran Quoc Tuan,Nguyen Tien Khi,Tran Quang Huy,Anh-Tuan Le
Reduced graphene oxide-wrapped silver nanoparticles (Ag@rGO) were synthesized by a simple photochemical process with the GO nanosheets as both a stabilizing and reducing agent. The synthesized Ag@rGO nanohybrids were used as a localized surface plasmon resonance (LSPR) colorimetric sensor for the detection of chromium(VI) and carbaryl. For chromium(VI), the result showed a color change from yellow to colorless and linear-dependence of the absorption intensity on the concentration of Cr(VI) in the range 0.1–25 μM. For carbaryl, the calibration curve presented a high level of linearity in the range of 0.1–50 μM corresponding to color changes from yellow to purple. The limits of detection (LODs) for Cr(VI) and carbaryl were found to be 31 nM and 42 nM, respectively. The novel Ag@rGO nanohybrids will become an excellent platform for colorimetric probes in the detection of Cr(VI) ions and carbaryl or other heavy metal ions/pesticides.
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危险品化学品经营许可证（带存储）