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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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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MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
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2021
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IF 3.927
Zhaohui Wu,Zhongfu Li,Min Wu,Jie Shen,Wenhui Feng,Xue Li,Difa Xu,Shiying Zhang,Nan Ma
It is inevitable to form invalid Type I heterostructure of BiOCl/bismuth-based photocatalysts due to the wide bandgap of BiOCl , which could only transfer the charge carriers efficiently, rather than separate. Herein, two-dimensional (2D) Type I van der Waals heterostructure of BiO 2-x /BiOCl nanosheets were prepared through a solvothermal route, and massive defects and multiple pores were in-situ constructed on the BiO 2-x /BiOCl nanosheets simultaneously. The defective and porous van der Waals structure of BiO 2-x /BiOCl ultrathin nanosheets possessing enhanced internal electric field , induced defect level, and reduced interfacial barriers, promoting both efficient transfer and separation of charge carriers. Furthermore, the massive defects of BiO 2-x /BiOCl porous nanosheets provided higher reactivity owing to its more hydrophilic surface . As a result, the BiO 2-x /BiOCl nanosheets boosted the photocatalytic performance of Cr (VI) reduction and Rhodamine B (RhB) degradation when employing LED as simulated solar light. Based on the results, a plausible photocatalytic mechanism of Cr (VI) removal and RhB photodegradation was illustrated. We expected that this work could provide a feasible route to design distinctive heterostructure photocatalysts for improved photocatalytic performances under simulated solar light.
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Nano Energy
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2021
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IF 17.881
Wenrou Tian,Jiahao Qiu,Najun Li,Dongyun Chen,Qingfeng Xu,Hua Li,Jinghui He,Jianmei Lu
Piezocatalysis that converts mechanical energy into chemical energy plays an important role in environmental purification and energy regeneration. In this work, a piezoelectric membrane of carbon nanofibers coated by few-layers SnS 2 nanosheets , a typical layered transition metal dichalcogenides (TMDs), for the first-reported piezocatalysis of hexavalent chromium (Cr (VI)) and bisphenol A (BPA). A boosted removal efficiency of Cr (VI) and BPA under ultrasonication are 3 and 4 times higher than that under illumination, respectively, which is attributed to the built-in electric field and band bending derived from the piezoelectricity of SnS 2 as well as the outstanding electronic liquidity of CNFs substrate. It was also found that the most oxidizing ·OH can be generated in SnS 2 /CNFs for piezocatalytic oxidative degradation of BPA compared to the absence of ·OH under illumination. Finally, the possible piezocatalytic mechanism of SnS 2 /CNFs is proposed. So it provides a new view on piezocatalysis of TMDs for environmental remediation by collecting mechanical energy.
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APPLIED SURFACE SCIENCE
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2021
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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
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2021
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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
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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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ANALYTICAL CHEMISTRY
·
2020
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IF 6.785
Ningyi Chen,Bingcai Pan
Most metal probes based on gold nanoparticles (AuNPs) are designed for free metal ions in synthetic waters, and very few are applicable in the detection of metal–organic complexes ubiquitous in real water samples. In this study, we proposed a novel colorimetric nanoprobe strategy for complexed Cr(III) species based on the analyte-induced aggregation of AuNPs, as coated by a cationic surfactant tributylhexadecylphosphonium bromide (THPB) instead of traditional carboxyl modifiers. Such a detection system could be realized via both naked eye and/or UV–vis spectroscopy with detection limits of 8.0 and 0.29 μM, respectively, much lower than its allowable maximum level in industrial effluent as regulated by China EPA (1.5 mg Cr/L, ∼30 μM). The proposed detection system also exhibits high selectivity against various interfering substances including free ions, small organic molecules, and other metal–citrate complexes. The unique hydrolysis and extremely slow decomplexation of Cr(III) are believed to favor the formation of the specific interaction between Cr(III)–citrate and THPB-AuNPs, as verified by X-ray photoelectron spectroscopy characterization, thus endowing the nanoprobe with specific discrimination of the complexed Cr(III) via the aggregation of THPB-AuNPs. Also, the THPB-AuNPs could be stored at room temperature for 30 days and maintain constant detection performance. Moreover, the quantitative detection of Cr(III)–organic complexes with the background of various real water samples agreed well with that based on inductively coupled plasma atomic emission spectrometry, making it an attractive alternative for on-site detection of authentic samples containing Cr(III)–organic species.
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JOURNAL OF ELECTROANALYTICAL CHEMISTRY
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2021
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IF 4.464
Cheng Liu,Lei Jin,Jia-Qiang Yang,Fang-Zu Yang,Zhong-Qun Tian
In this paper, the effects of complexing agents (oxalic acid and glycine) and Fe(II) ions on the electro-reduction of Cr(III) ions are studied carefully. Based on the electrochemical analyses, both the complexing agents and Fe(II) ions can obviously decrease the cathodic polarization in the electro-reduction of Cr(III) ions, and the Fe(II) ions can also be co-deposited with Cr(III) ions. One water molecule in [Cr(III)(H 2 O) 6 ] 3+ ion is substituted by one oxalic acid or glycine to form an electrochemically active penta-aqua-Cr(III) coordination ion. In situ infrared spectroscopy and energy dispersive spectroscopy reveal the typical induced-deposition mechanism of ferrochrome alloy. Fe(II) ions are firstly reduced to Fe crystal nuclei, then Cr and Fe atoms grow on the Fe nuclei to form ferrochrome alloy.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2021
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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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