JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY
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2020
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IF 3.306
Xiaochun Zheng,Shoutian Ren,Qixiao Gai,Wenjun Liu
Fluorescence quenching of carbon dots (CDs) has been widely used for ions detection, but it usually exhibits poor selectivity for specific ions, so how to enhance their response selectivity is still an urgent task. In this paper, CDs and carbon nitride (C 3 N 4 ) nanosheets are prepared by pyrolysis and thermal oxidation method, respectively, followed by their ultrasonic mixing to synthesize CDs/C 3 N 4 composites. They are characterized by transmission electron microscope, X-ray diffractometer, X-ray photoelectron spectrometer, Fourier transform infrared spectroscopy, UV–vis and fluorescence spectrophotometer. The synthesized CDs and C 3 N 4 nanosheets both exhibit strong fluorescence response to multiple ions. As a comparison, CDs/C 3 N 4 composites exhibit highly enhanced selectivity to Cr 6+ as a result of partial consumption of -NH 2 groups and C N bonds or their reduced binding ability. Meanwhile, our CDs/C 3 N 4 probe exhibits high sensitivity of 54 %, short response time of less than 1 min, low detection limit of 0.39 μM, wide linear response interval of 2.0−80.0 μM and high stability.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2020
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IF 3.573
Qiqi Zhou,Guijian Liu
The presence of sulfa antibiotics in water is becoming increasingly serious and actions need to be taken to establish an effective wastewater purification process for their removal. MIL-101(Cr)@AC was prepared by incorporating activated carbon into the MIL-101(Cr) framework to reduce unused voids in MIL-101. MIL-101(Cr)@AC has a high specific surface area and was successfully synthesized and activated with urea. In this study, the adsorptive removal of the sulfonamide antibiotic, sulfacetamide (SA), from wastewater was studied using urea-activated MIL-101(Cr)@AC for the first time. High SA adsorption efficiency was observed, and an adsorption equilibrium was reached within approximately 60 min. The adsorption kinetics and isotherm records were best fitted using the Langmuir model and a pseudo-second-order model, respectively. Therefore, according to the result of adsorption, a possible mechanism was proposed. Hydrogen bonding between −NH2 on the grafted urea-MIL-101(Cr)@AC and −SO2 groups in SA resulted in an increase in adsorption efficiency. In addition, urea-MIL-101(Cr)@AC exhibited excellent reusability, which is attractive for potential applications in adsorbing SA from wastewater.
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CHINESE JOURNAL OF CHEMISTRY
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2020
·Vol. 38
·期 11
·1332-1338
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IF 3.826
Meichen Li,Yaru Li,Jingyu Zhao,Mingcheng Li,Yongchuan Wu,Ping Na
Summary of main observation and conclusion The AL-P25 composites (AL = alizarin, P25 = nano titanium dioxide) with oxygen vacancies were synthesized by a simple hydrothermal method and applied for the photoreduction of Cr(VI) under visible light. The AL-P25 composites were characterized by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy analysis, Fourier transform infrared spectrometer, thermo-gravimetric analysis, UV–vis diffuse reflectance spectroscopy, photoluminescence spectroscopy and electron paramagnetic resonance spectroscopy. The results suggested that the AL-P25 composites were successfully prepared, and alizarin was linked to P25 via Ti—O—C bonds. AL-P25 composites represented excellent photoreduction efficiency on Cr(VI) under visible light, which was 99.4% after 60 min of illumination. Finally, a photocatalytic mechanism of AL-P25 composites was proposed that ligand-metal charge transfer (LMCT) process between alizarin and P25 effectively enhances separation efficiency of photogenerated electrons and holes.
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Scientific Reports
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2021
·Vol. 11
·期 1
·1-15
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IF 4.38
Eltaweil Abdelazeem S.,El-Monaem Eman M. Abd,Mohy-Eldin Mohamed S.,Omer Ahmed M.
An efficient composite was constructed based on aminated chitosan (NH 2 Cs), attapulgite (ATP) clay and magnetic Fe 3 O 4 for adsorptive removal of Cr(VI) ions. The as-fabricated ATP@Fe 3 O 4 -NH 2 Cs composite was characterized by Fourier Transform Infrared Spectroscopy (FTIR), Thermal Gravimetric Analyzer (TGA), Scanning Electron Microscope (SEM), Zeta potential (ZP), Vibrating Sample Magnetometer (VSM), Brunauer–Emmett–Teller method (BET) and X-ray photoelectron spectroscope (XPS). A significant improve in the adsorption profile was established at pH 2 in the order of ATP@Fe 3 O 4 -NH 2 Cs(1:3) > ATP@Fe 3 O 4 -NH 2 Cs(1:1) > ATP@Fe 3 O 4 -NH 2 Cs(3:1) > Fe 3 O 4 -NH 2 Cs > ATP. The maximum removal (%) of Cr(VI) exceeded 94% within a short equilibrium time of 60 min. The adsorption process obeyed the pseudo 2nd order and followed the Langmuir isotherm model with a maximum monolayer adsorption capacity of 294.12 mg/g. In addition, thermodynamics studies elucidated that the adsorption process was spontaneous, randomness and endothermic process. Interestingly, the developed adsorbent retained respectable adsorption properties with acceptable removal efficiency exceeded 58% after ten sequential cycles of reuse. Besides, the results hypothesize that the adsorption process occurs via electrostatic interactions, reduction of Cr(VI) to Cr(III) and ion-exchanging. These findings substantiate that the ATP@Fe 3 O 4 -NH 2 Cs composite could be effectively applied as a reusable adsorbent for removing of Cr(VI) ions from aqueous solutions.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2021
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IF 3.764
Ju Liu,Dandan Hao,Huiwen Sun,Yu Li,Jianlin Han,Bo Fu,Jiancheng Zhou
In this Article, a hybrid foam was fabricated through the integration of amine-functionalized Fe-MOF (MIL-101-NH2) into cellulosic matrix. The existence of enormous group linkages and ionic bonding interactions among the composite foam network leads to a uniform dispersion of MIL-101-NH2 and high affinity between the MOF and cellulose skeleton. As-prepared hybrid foams were utilized as photocatalysts to reduce toxic hexavalent chromium ions (Cr(VI)) under visible light. Optimal performance was observed over CM-1 (with a MIL-101-NH2 and nanocellulose mass ratio of 1:1). When compared to pure MOF nanoparticle counterparts, the CM-1 foam presented preferable and more efficient Cr(VI) removal performance. The reasons could be attributed to the hierarchal pore structure and uniform MOF loading. Moreover, the flexible foams could be easily separated from the solution and preserved more than 80% removal efficiency of Cr(VI) after 10 runs. This work would shed light on how to construct high-efficiency photocatalysts for environmental governance from sustainable materials.
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Journal of Environmental Chemical Engineering
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2021
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IF 5.909
Qin He,Yangjie Fu,Xueying Ge,Abdullah M. Al-Enizi,Ayman Nafady,Qi Wang,Shengqian Ma
Novel Fe-BDC/Fe-2MI heterojunction (H 2 BDC: terephthalic acid, 2MI: 2-methylimidazole) was prepared via a one-pot solvothermal method. Herein, mixed ligands (H 2 BDC and 2MI) was applied to form complex with Fe(III). Interestingly, the presence of 2MI can regulate the structure of Fe-BDC. Spindle-like MIL-88B(Fe) was observed in Fe-BDC/Fe-2MI composite, while MIL-53(Fe) was identified in naked Fe-BDC. By employing photoelectrochemical characterizations, Fe-BDC/Fe-2MI was optimized at an initial molar ratio of 1:0.5:10 for Fe(III):H 2 BDC:2MI, which exhibited the highest photocurrent response, lowest charge transfer resistance, and fastest surface reaction kinetics as compared to the individual Fe-BDC and Fe-2MI. Due to the formation of the heterojunction which lead to beneficial photoelectrochemical properties, the as-prepared samples exhibited boosted photocatalytic activity for Cr(VI) reduction. The calculated pseudo-first-order rate constant ( k ) was 0.046 min −1 for Fe-BDC/Fe-2MI, which was 15.3 and 6.6 times that of Fe-BDC (0.003 min −1 ) and Fe-2MI (0.007 min −1 ), respectively. Moreover, the optimized Fe-BDC/Fe-2MI demonstrated superior performance with negligible loss in activity after 4 cyclic runs.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
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2021
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IF 8.128
Kairuo Zhu,Lili Chen,Njud S. Alharbi,Changlun Chen
Magnetic carbon materials promise distinct advantages in the decontamination of heavy metal ions. In this work, a novel interconnected hierarchical nickel-carbon (Ni@IHC) hybrid was synthesized by combining the solvothermal method with a one-step pyrolysis under argon atmosphere. Benefitting from 3D flower-like morphology, interconnected porous nanosheets, large surface area, and abundant Ni nanoparticles, Ni@IHC hybrids can remove Cr(VI) within 25 min by using formic acid (FA) as a reductant at 25 ℃. Furthermore, the experimental parameters that can affect the material catalytic performance such as initial Cr(VI) concentration, catalyst dosage, FA concentration, and temperature were also investigated in detail. It was found that highly dispersed Ni nanoparticles contributed significantly to the reduction process. More importantly, the embedded Ni nanoparticles favor fast separation by a magnet and were helpful for the recycles use. This Ni@IHC hybrid was obtained by a facile and easy scale-up method, resulting in the fast transformation of Cr(VI) into Cr(III).
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SEPARATION AND PURIFICATION TECHNOLOGY
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2021
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IF 7.312
Guanglai Mo,Linxi Wang,Jianhong Luo
It is a challenge to achieve efficient photocatalytic activity of pure MOFs. Herein, the defective NH 2 -MIL-125(Ti) with adjustable linker vacancy level was successfully created by thermal treatment. The band gaps of samples decreased and the more Ti-O clusters on the surface of the samples can be achieved as the time of thermal treatment increased from 0 to 500 min, both of which facilitated the photocatalytic activity for the reduction of Cr(VI). Moreover, the ligands from the surface to the inside of the samples were successively decarboxylated, resulting in the declined specific surface area and the increased proportion of mesoporous and the defect level. The moderate defect level in NH 2 -MIL-125(Ti) can be obtained as the time of thermal treatment was 300 min, which facilitated the separation of photogenerated charges, contributing to the highest photocatalytic activity for reduction of Cr(VI), which was 9.2 times than that of the initial MOFs. However, the excessive linker vacancy defect level in NH 2 -MIL-125(Ti) may result in the seriously affected crystal structure and the retarded separation of photogenerated charges.
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Catalysis Science & Technology
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2021
·Vol. 11
·期 18
·6271-6280
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IF 6.119
Jiaqi Dong,Jianqiang Hu,Anyu Liu,Jiale He,Qingling Huang,Yanru Zeng,Wenjing Gao,Zhen Yang,Yongcai Zhang,Yong Zhou,Zhigang Zou
Direct Z-scheme MgIn2S4/Bi2WO6 hierarchical heterostructures were simply fabricated via immobilising MgIn2S4 nanoflakes onto the surface of Bi2WO6 hierarchical nanosheet-like structures towards photocatalytic reduction of Cr(VI). The analyses of the energy band structure, UPS tests and DMPO-ESR spin-trap experiments confirm that the intimate MgIn2S4/Bi2WO6 heterointerface allows an efficient Z-scheme interfacial charge migration route between MgIn2S4 and Bi2WO6, leading to higher redox ability of photoexcited carriers, and thus favours the separation of photoexcited carriers, proved by the results of PL spectroscopy, photoluminescence decay traces, transient photocurrent densities and EIS. In addition, the MgIn2S4/Bi2WO6 heterostructures also exhibit obviously enhanced ultraviolet-visible-light absorption according to UV-vis DRS analysis, and can generate more electron–hole pairs under UV-visible light illumination, effectively improving the photocatalytic activity. Therefore, because of their synergistic effects, all the MgIn2S4/Bi2WO6 hierarchical heterostructures show distinctly improved photoreduction activities for Cr(VI), compared with pure Bi2WO6. The optimal hybrid (MIS/BWO-0.35) displays nearly 100% Cr(VI) reduction into Cr(III) after 40 min of simulated sunlight illumination, which is better than the majority of the reported Bi2WO6 and other semiconductor photocatalysts before. Its reaction rate constant for the photoreduction of Cr(VI) (0.1063 min−1) is about 4.5 times higher than that of the pristine Bi2WO6 (0.0237 min−1). This work provides a valid approach for developing efficient Z-scheme photocatalytic materials in removing Cr(VI).
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2019
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IF 4.784
Ruiting Wen,Biyang Tu,Xiaohong Guo,Xiaoqin Hao,Xia Wu,Haisheng Tao
A simple iron/carbon composite was prepared by ion exchange and carbothermal reduction, and the characterization results showed that this material contained a large amount of nanoscale zero-valent iron. Then above material was coated with alginate to form a stable gel, which combined adsorption and reduction to remove Cr(VI) efficiently and controllably. The experiment showed that the optimal conditions for Cr(VI) removal were pH value, dosage and Cr(VI) concentration of 2, 2 g L −1 and 20 mg L −1 , respectively. For 150 mL of 20 mg L −1 Cr(VI) solution, the removal efficiency could reach 100% in 6 h (dosage: 2 g L −1 ). Compared with activated carbon-alginate complex and pure alginate, the introduction of nanoscale zero-valent iron greatly accelerated the rate of Cr(VI) removal. In addition, adsorption isotherm and kinetics conformed to Freundlich and Elovich model, respectively. Under pH 2, the release of iron ion increased linearly with time and reached 51.87 mg L −1 in 8 h. The mechanism of Cr(VI) removal of iron/carbon composite coated with alginate might be controlled by two steps: the initial adsorption and fixation, and subsequent reduction. In general, the material is efficient, recyclable and controllable, which provides a new idea for the treatment of chromium-containing wastewater.
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SCIENCE OF THE TOTAL ENVIRONMENT
·
2019
·
IF 5.589
Songlin Han,Yanan Zang,Yue Gao,Qinyan Yue,Ping Zhang,Wenjia Kong,Bo Jin,Xing Xu,Baoyu Gao
Modified anion exchange resin (EDE-D301) was synthesized by mixing monomers : epichlorohydrin (ECH), dimethylamine (DMA), ethylenediamine (EDA) with the weakly alkaline anion exchange resin D301 through in-situ polymerization method. Adsorption performance of EDE-D301 for removing Cr(VI) contaminants was investigated in batch and column systems. Physicochemical properties of the anion exchange resins were characterized to determine the adsorption mechanism and regeneration ability. Characteristic results revealed that EDE-D301 showed enhanced surface area, positive charge and contents of N and Cl elements, indicating that the modifying reagents of monomers were successfully polymerized in the resin. The experimental adsorption data fitted well to the pseudo-second-order kinetic model and the Langmuir isotherm model. The fixed-bed experiments showed that the exhaustion time increased with increasing the bed depth, and decreased with increasing the flowrate and influent concentration. Adsorption capacity for Cr(VI) onto EDE-D301 was determined at a maximum level of 298 mg·g −1 , and remained at 93% after four consecutive cycles. FTIR and XPS analysis indicated that the ion exchange and complexation were responsible for the Cr(VI) adsorption.
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CHEMOSPHERE
·
2019
·
IF 5.108
Yueyue Shi,Dazhen Xiong,Yangyang Zhao,Tiemei Li,Kaige Zhang,Jing Fan
Highly efficient and selective separation of Cr (VI) is great of importance in environmental pollution control . In this study, a novel family of hydrophobic DESs has been designed and synthesized by mixing parabens and quaternary ammonium, and then used to extract heavy metal Cr (VI) from water phase and the content of Cr (VI) is measured by 1,5-diphenylcarbazide spectrophotometry . It is found that the hydrophobic DESs exhibit excellent extraction performance towards Cr (VI). At the 1:1 M ratio of DES to Cr (VI), the extraction capacity is as high as 66.7 mg g −1 , the extraction efficiency is greater than 90% for ultra-trace Cr (VI) (0.51 μg L −1 ), and the preconcentration factor is up to 700. When the concentration of coexisting metal ions (Cd 2+ , Cu 2+ ) and organic compounds ((C 6 H 10 O 5 ) n , C 6 H 12 O 6 ·H 2 O) is 2000 times that of Cr (VI), the extraction efficiency is still above 90%. Compared with ionic liquid extractants, the preparation process of DES is very simple, the atomic utilization rate is 100%, and no waste is produced. These hydrophobic DESs have been used to separate and enrich Cr (VI) from actual water samples with satisfactory recoveries. The possible extraction mechanism is investigated by FT-IR and 1 H NMR.
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