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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RSC Advances
·
2020
·Vol. 10
·期 46
·27775-27787
·
IF 3.119
Qining Liu,Honghui Liu,Huixia Chen,Xinrun Wang,Dahai Hu,Xichuan Cheng,Hongbin Xu
In this paper, the reoxidation behaviours of CrOOH and Cr(OH)3 are investigated as the major reduction products of Cr(VI). The atmosphere oxidation of Cr(III) is studied in the environment of soil without manganese and hydrogen peroxide. The influence of temperature and pH value on the oxidation rate of Cr(III) is examined by Experiment methods in details. According to the experimental results, the oxidation of Cr(III) is promoted in the environment with high pH value, however, the oxidation process is stable with temperature. The oxidation process of CrOOH and Cr(OH)3 are theoretically researched by thermodynamic calculation and density functional theory (DFT) simulation. The results of DFT indicate that both CrOOH and Cr(OH)3 are oxidized during the chemical adsorption process of O2 in alkaline environment. With the transformation from Cr(III) to Cr(VI), the Cr–O covalent bond forms in the adsorption process. The crystal structure difference between CrOOH and Cr(OH)3 leads to the different oxidation reaction between O2 and Cr(III). The significant alteration of oxidation process in (110), (310), (321) crystal planes is also observed indicating the crystal orientation dependence. Based on the chemical reaction kinetics, the chemical equivalent constant K of CrOOH is higher than Cr(OH)3, illustrating higher chemical stability in air. In summary, both experimental study and theoretical analysis on the reoxidation phenomenon of Cr(III) reduced from Cr(VI) in natural environment demonstrate that not only the external factors such as temperature and pH value but also the crystal structure of Cr(III) compound have dramatic influence on the oxidation process.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2020
·
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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JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY
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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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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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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2019
·
IF 3.375
Qian Chen,Yi Feng,Rongrong Tian,Jinghang Chen,Anqing Wang,Jianfeng Yao
Photosensitization is a promising way to make UiO-66 visible light responsive. In this work, zirconium (Zr) precursors and synthetic methods (solvent-assisted or nonsolvent-assisted) were found to significantly affect the electric charge and the defect sites of UiO-66. UiO-66 with enhanced adsorption and photosensitized photocatalytic ability was then obtained. When ZrOCl2·8H2O was applied as Zr-precursor in a nonsolvent method, defect rich UiO-66 (UiO–OCl–N) was achieved with higher Cr(VI) adsorbing ability and improved photosensitized photocatalytic ability. Moreover, with the coexistence of Rhodamine B in Cr(VI) solution, photocatalytic performance of UiO-66 can be further enhanced.
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CHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 16.744
Chen Wang,Mingjie Huang,Wentao Hu,Wei Xiang,Tao Zhou,Juan Mao,Feixiang Zan,Xiaohui Wu
The carcinogenic and hard-to-dispose Cr(VI) in high-salinity industrial wastewater has caused severe environmental problems. Herein, a novel hollow spherical CuFe 2 O 4 spinel oxide with concentrated confined oxygen vacancies (HS/CuFe 2 O 4 -OVs) was developed for Cr(VI) decontamination. Such a fancy material delivers a remarkable removal rate of 0.041 min −1 , approximately-one order of magnitude higher than the commonly reported iron-based materials. The OVs in the confined space could exert dual effects on Cr(VI) removal from the aspects of enhanced stabilization via local electronic structure regulation and strengthened immobilization via electron conductivity modulation. Importantly, due to the highly sensitive response of Cr(VI) to the changed confined OVs content, the HS/CuFe 2 O 4 -OVs showed higher selectivity for Cr(VI) removal in the interference of high concentration salts than its nonhollow-structured counterpart and can successfully treat Cr(VI)-contaminated industrial wastewater with high salinity. This work opens up a new concept for rational design of robust spatial confined architectures for Cr(VI) treatment.
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FUEL
·
2023
·
IF 7.4
Wenting Lin,Jianxian Li,Ziyu Zengcai,Baofang Zhang,Xiaoping Wu,Yunhong Pi,Tiejun Wang
Photothermal-driven reforming of methanol solution to hydrogen (PTRM) is an attractive way for sustainable in-situ hydrogen (H 2 ) supply by solar energy. But the effective activation of MeOH and H 2 O to improve H 2 production kinetics at low temperatures faces really challenge. As the cleavage energy barrier of C H bond in methanol is much higher than that of O H bond dissociation, here, we propose the use of CuInS 2 with high interfacial hydroxyl activation capacity to integrate with MIL-101(Cr) matrix via in-situ encapsulation strategy. The pore confinement and site isolation of Cr-MOF matrix (MIL-101(Cr)) keep the high dispersion of CuInS 2 (4.20 nm) and prohibit its agglomeration in PTRM. With synergistically photothermal effect, the insertion of CuInS 2 not only provides a high-speed channel for photoexcited charge migration through the interface between CuInS 2 and MIL-101(Cr) but also enhances the dehydrogenation activity of MeOH and H 2 O effectively as an electron-enriched tank. Moreover, the excellent ability of CuInS 2 to dissociate H 2 O molecules at low temperature promoted the formation of abundant interfacial OH, which reinforces the C H bond cleavage of MeOH to decline the apparent activation energy (26%) and boost the H 2 evolution kinetics (36233.0 μmolg cat -1 h −1 ). Encouragingly, CuInS 2 @MIL-101(Cr) with an exceptional total turnover number (TON) climbing up to 16,775 in 65 h of run without catalyst deactivation. This work provides an important insight for the rational design of ultra-stable photo-thermal catalysts toward solar-driven reforming of methanol solution to hydrogen and conducive to the high activity performance in hydrogen-powered polymer electrolyte membrane (PEMFC) fuel cell.
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Water Science and Engineering
·
2023
·
IF 4
Xiao-jie Guo,Wei-kang Fu,Jing-yuan Ma,Bo-jun Xi,Chen Wang,Meng-yao Guan
Lignocellulose has the potential to become a bio-based adsorbent due to its biodegradability and renewability. In this study, a novel polydopamine-functionalized-lignin (lignin@PDA), prepared via self-polymerization of dopamine (PDA) on lignin, was used as a bio-based adsorbent for rapid scavenging of hexavalent chromium (Cr(VI)). The morphology, functional groups, crystalline structure, and chemical composition of lignin@PDA were characterized with a scanning electron microscope–energy dispersive spectrometer, Fourier transform infrared spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The Cr(VI) adsorption process of lignin@PDA was studied using batch experiments as a function of pH, ionic strength, adsorbent dose, and contact time at room temperature. The adsorption rate of lignin@PDA was five times greater than that of the unmodified lignin, with a maximum adsorption capacity of 102.6 mg/g in an acidic medium. The adsorption of Cr(VI) on lignin@PDA fit the pseudo-second-order equation and the Freundlich model, indicating that the adsorption process was mainly dominated by chemisorption and surface complexation. The thermodynamic parameters showed that adsorption of Cr(VI) on lignin@PDA was an endothermic and spontaneous process. The X-ray absorption fine structure results showed that sorption and reduction of Cr(VI) into Cr(III) occurred simultaneously on lignin. Moreover, PDA coating not only improved the reactivity of lignin but also promoted the complete reduction of Cr(VI) by lignin. According to these results, polydopamine-functionalized-lignin is a promising bio-based adsorbent for immobilization of Cr(VI) from wastewater.
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CHEMOSPHERE
·
2023
·
IF 8.8
Aikui Chen,Yao Huang,Hui Liu
Sulfidated nanoscale zerovalent iron (S-nZVI) has been extensively studied for the reductive removal of Cr(VI), but its applicability is limited by agglomeration and unexpected efficiency reduction. In this study, chitin microsphere supported sulfidated nanoscale zero-valent iron (S-nZVI@Chi-M) was prepared by in-situ one-step reduction method and used to remove Cr(VI) from water. Compared to chitin and chitosan powder, Chi-M with nanofibrous structure and large surface area performed best in stabilizing S-nZVI with a Fe 0 loading content of 3.01 wt%. The S-nZVI particles were homogeneously distributed on the surface of Chi-M, effectively avoiding agglomeration. Compared with bare nanoparticles and supported nZVI, S-nZVI@Chi-M showed significantly enhanced Cr(VI) removal capacity (924.5 mg Cr(VI) for per gram of effective Fe 0 ). The influences of sulfidation degree, dosages, initial Cr(VI) concentration, pH, DO, humic acid and typical ions on Cr(VI) removal kinetics were further studied. S-nZVI@Chi-M could be recycled for at least 4 times with acceptable reactivity. The mechanism investigation results indicated that the Cr(VI) removal was a complex process of reduction, adsorption and co-precipitation under the synergistic effect of Chi-M and S-nZVI. This work provides new ideas for the continuous fabrication of highly reactive nanoparticles, hopefully expanding the application scope of biomass resources in pollution remediation.
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