APPLIED SURFACE SCIENCE
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2021
·
IF 6.707
Yanlin Jia,Zizhao Wang,Xiu-Qing Qiao,Lei Huang,Shenglong Gan,Dongfang Hou,Dong-Sheng Li
Metallic MoSe 2 with distinct platinum-like electronic configuration and compelling band gap structure exhibits zero approaching Gibbs free energy for H atom, hence can be approved as an ideal cocatalysts for H 2 evolution. However, the reports on MoSe 2 cocatalyst still leaves much room. Here, two dimensional ultrathin MoSe 2 nanosheets bedecked Zn 0.5 Cd 0.5 S nanoparticles were reported as efficient photocatalyst, in which metallic MoSe 2 nanosheets cocatalyst will do duty for electron sink to promote the separation of charge carriers and prolong the electrons lifetime, thus benefiting the improved photocatalytic H 2 evolution activity. As a result, Zn 0.5 Cd 0.5 S/MoSe 2 composite with an optimized 9 wt% MoSe 2 presents a higher H 2 evolution activity of 4853.3 μmol g -1 h −1 , 3.57 folds of pure Zn 0.5 Cd 0.5 S sample (1361.0 μmol g -1 h −1 ). Meanwhile, the greatly enhanced photo-reduction efficiency for toxic heavy metal Cr (VI) ion by Zn 0.5 Cd 0.5 S/MoSe 2 composite further certifies the promoted separation of electron- hole pairs. These results turned out that MoSe 2 is qualitied as candidate to serve as promising co-catalyst for photocatalyst energy conversion and decontamination.
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Catalysis Science & Technology
·
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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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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APPLIED SURFACE SCIENCE
·
2021
·
IF 6.707
Xiao Zhang,Ping Yang,San Ping Jiang
Photo-catalytic reduction of highly toxic Cr(VI) using graphitic carbon nitride (g-C 3 N 4 ) based photocatalysts under visible light irradiation condition has been attracting considerable attention recent years. Here, we report the development of heterostructured NiCo-layered double hydroxides (LDHs) grown horizontally on g-C 3 N 4 nanosheets with different degrees of crystallinity (amorphous to crystalline), NiCoLDH/g-C 3 N 4 , with high photocatalytic activity for the reduction of toxic hexavalent chromium ions (Cr(VI)) as well as high adsorption capability for congo red (CR) photodegradation under visible light irradiation. The presence of NiCoLDH nanoparticles promotes the adsorption of the anionic pollutants while g-C 3 N 4 in the heterostructure promotes fast photodegradation of CR and reduction of Cr(VI). The NiCoLDH/g-C 3 N 4 composite prepared using amorphous-crystalline g-C 3 N 4 homojunctions shows the best adsorption performance. The kinetic data demonstrates improved correlation coefficient for the pseudo-second-order (R 2 > 0.99) and Freundlich isotherm model. The NiCoLDH/g-C 3 N 4 composite shows an improved separation efficiency of photogenerated electron and hole pairs, leading to its improved Cr(VI) adsorption and photo-reduction performance. The monolayer adsorption capacities of CR and Cr(VI) of the NiCoLDH/g-C 3 N 4 heterostructured composite can be as high as 1100 and 46 mg/g at 30 °C, respectively. This work provides new perspectives for the development of highly efficient g-C 3 N 4 -based composite photocatalysts for wastewater treatment related applications.
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CHEMOSPHERE
·
2021
·
IF 7.086
Jinxiong Wu,Xiuling Yan,Li Li,Jiahua Gu,Ting Zhang,Lanlan Tian,Xintai Su,Zhang Lin
Coal gangue (CG) is one of the largest industrial solid wastes in the world produced during the process of coal mining . The accumulation of CG is easy to cause ion leakage , which is harmful to the environment and human body. The recovery and utilization of CG are imminent. In the process, a hierarchical porous carbon (HPC) adsorbent with excellent adsorption property for Cr(VI) and rhodamine B (RhB), was prepared from CG by a two-step method and characterized by SEM, TEM, XRD , XPS, TPD and BET. The results revealed that the specific surface area of HPC is up to 2012.7 m 2 g −1 , and its adsorption capacities for Cr(VI) and RhB are reached 320.51 and 3086.42 mg g −1 . The adsorption mechanism of RhB was the synergetic effect of physics and chemistry. While XPS results suggested that hierarchical porous carbons (HPCs) only have a chemisorption effect on Cr(VI). This study provided an idea for the preparation of HPCs from CG to remove inorganic and organic pollutants such as heavy metal Cr(VI) and RhB in water.
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高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2021
·
IF 6.953
Huimei Shan,Chunya Zeng,Chaoran Zhao,Hongbin Zhan
This study is the first to evaluate the effects of Iron oxides (FeO x ) species and their decoration on graphene oxide/chitosan (GO/CS) composites for Cr(VI) removal and the possibility of Fe secondary pollution. Results show that Fe(III) is a better decoration material than Fe(II) and decoration through immersion-evaporation shows a higher adsorption capacity of Cr(VI) ( Q e ) than co-precipitation. Fe 2 O 3 -GO/CS as the only eco-friendly composite for enhanced Cr(VI) removal is further used for batch adsorption experiments, characterization, kinetics, isotherms, and thermodynamic studies. It is found that Cr(VI) removal mainly includes electrostatic attraction between Cr(VI) oxyanions and surface -NH 3 + and -OH 2 + , and the adsorbed Cr(VI) partially reduces to Cr(III). Q e increases with the increasing initial Cr(VI) concentration, contact time, and temperature, while decreases with the increasing pH and mass and volume ratio (m/v). The coexisting ions (Cl − , NO 3 − , SO 4 2− , PO 4 3− , As, Fe, and Pb) can cause an obvious decrease of Q e . The removal efficiency ( R e ) and Q e are 94.3% and 83.8 mg/g, respectively under the optimal conditions. After five times of regeneration, R e is still as high as 84% and Q e drops about 2.6%. Cr(VI) adsorption is spontaneous and endothermic, which is best fitted with the Sips model, and the fitted maximum Q e is 131.33 mg/g.
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Journal of Environmental Chemical Engineering
·
2020
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IF 4.3
Xing Chen,Xu-Xu Ke,Yao Liu,Rohan Weerasooriya,Heng Li,Yu-Cheng Wu
Chromium readily undergoes redox speciation, and Cr(VI) oxidation state is ubiquitous and mobile in the environment. Under physiological conditions, Cr(VI) reduction yields species as Cr(V) or Cr(VI), which shows reactivity towards DNA damaging. Therefore, accurate detection of Cr species in the environmental compartment is of utmost importance. In compliance with green chemistry, Au/mpg-C 3 N 4 nanocomposites were successfully fabricated by ultra-violet photo-reduction without a reducing agent. The Au/mpg-C 3 N 4 nanocomposites were characterized by scanning electron microscope (SEM), X-ray diffractometry (XRD), X-ray photoelectron spectrometry (XPS), and infrared spectrophotometry. Well-dispersed gold nanoparticles with an average diameter of 50 nm decorated on mpg-C 3 N 4 . We developed a method to determine Cr(VI) with excellent sensitivity (0.002196 μA/ppb) and detection limit (14.7 ppb) using Au/mpg-C 3 N 4 modified glassy carbon working electrode by linear sweep voltammetry (LSV). The same electrode can use in real-time Cr(VI) monitoring using amperometry. The new sensor is stable and free from interferences from other species in natural water, and it can also be used in real-time Cr(VI) monitoring over wide concentration ranges.
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JOURNAL OF POLYMERS AND THE ENVIRONMENT
·
2020
·Vol. 28
·期 8
·2199-2210
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IF 2.572
Pei Ruihan,Li Qiqi,Liu Jianting,Yang Guifang,Wu Qiong,Wu Minya,Tong Shengxuan,Lv Yuancai,Ye Xiaoxia,Liu Yifan,Liu Minghua
Abstract Removal of low content of Cr(VI) from water is a critical challenge for water environment protection. Herein, an acrylamide-thiosemicarbazide cellulose aerogels (ATC) was designed by dissolving, grafting and freeze-drying to introduce thiosemicarbazide onto acrylamide-cellulose aerogels (AMC) via Schiff based reaction. The resultant ATC was further employed as an efficient adsorbent to remove low content of Cr(VI) from wastewater by adsorption and reduction. The SEM, FT-IR, and BET results showed that the ATC was composed of well-developed pore structure and owned functional groups such as –NH 2 , C–S and C=S groups. Experimental results indicated that ATC exhibited excellent removal efficiency for 99% under low initial concentration (0.1–10 mg/L). The adsorption isotherms demonstrated ATC adsorbent according to a monolayer adsorption behavior following the Langmuir model with a calculated maximum adsorption capacity of 83.40 mg/g at pH 3, and the adsorption kinetics well obeyed the pseudo-first-order kinetic model. Importantly, the maximum effluent concentration of Cr(VI) was lower than 0.045 mg/L, meeting the standard of WHO (50 μg/L). Furthermore, the main removal mechanisms involved the synergistic effect of electrostatic interactions, reduction and chelation between the positively charged functional groups of adsorbent and the anionic Cr(VI) ions. Graphic Abstract
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高影响因子
CHINESE JOURNAL OF CHEMISTRY
·
2020
·Vol. 38
·期 11
·1332-1338
·
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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JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY
·
2020
·
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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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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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2019
·
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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