CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Yusof A.Y.A. Mohammed,A.M. Abdel-Mohsen,Qi-Jun Zhang,Mohammad Younas,Lu-Bin Zhong,Jia-Cheng E. Yang,Yu-Ming Zheng
Hexavalent chromium Cr(VI) is one of the most toxic heavy metal ions. Therefore, the removal of this contaminant from wastewater is of particular importance. Herein, a novel zeolitic imidazolate framework (ZIF-8) nanoparticles based electrospun polyacrylonitrile (PAN)/polyethylenimine (PEI) nanofibrous composite membranes (NCMs) were prepared and characterized by SEM, XRD, FTIR, TGA and other characterization techniques. The NCMs were tested for the adsorption of Cr(VI) from water. Results showed that the inclusion of PEI tailored the surface of the NCM to be superhydrophilic. The prepared electrospun NCM showed a high adsorption capacity for Cr(VI) (up to 403.5 mg·g −1 ) under ZIF-8 concentration of 5 wt%. More importantly, introducing ZIF-8 up to 5 % did not only increase the adsorption capacity but also enhanced the thermal stability, mechanical strength, and structure of the NCM. The experimental analysis of co-existing ions and the reusability of up to ten cycles showed that the optimized PAN/PEI@ZIF-8 NCM exhibited good selectivity and excellent stability for wastewater treatment. The adsorption kinetics followed the pseudo-second-order model and the adsorption isotherm could be fitted well by the Langmuir model. Thermodynamics revealed that the adsorption process was spontaneous and endothermic. The adsorption mechanism was found to be mainly electrostatic attraction and reduction. This study demonstrated the potential of ZIF-8-incorporated PAN/PEI NCMs for the removal of Cr(VI) from water.
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高影响因子
Journal of the Taiwan Institute of Chemical Engineers
·
2023
·
IF 5.7
Meng Chen,Huawei Fang,Chao Wang,Jixiang Xu,Lei Wang
Background Solar-driven water splitting is regarded as one promising green way to produce H 2 . Photo-reduction of hexavalent chromium (Cr(Ⅵ)) to hypotoxic Cr(III) can control the Cr(VI)-induced pollution. A key in these processes is to develop a photocatalyst with high specific surface area, good light absorption and efficient charge carrier separation. Methods A Co-encapsulated N-doped carbon (Co@NC) was prepared by pyrolysis ZIF-8@ZIF-67 precursor to modify CdSe quantum dots (QDs). The obtained catalyst was used to reduce Cr(Ⅵ) and split water under visible light irradiation. Significant findings Modification CdSe with Co@NC made obtained Co@NC/CdSe possessing enhanced visible-light absorption and photoexcited charge separation. The optimal 2%Co@NC/CdSe exhibited the excellent Cr(Ⅵ) reduction performance with a rate constant of 0.28 min –1 in the absence of sacrificial agent, as well as high H 2 evolution rate of 6.48 mmol g –1 h –1 in 10% lactic acid solution. The H 2 O 2 and electrons were the active species to reduce Cr(VI). This work gives a beneficial insight for improving the photocatalytic activity of QDs.
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CHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 16.744
Fenglei Liu,Shanshan Wang,Baowei Hu
Herein, a MXenes decorated nanoscale FeS composites were developed via electrostatic self-assembly strategy to achieve efficient U(VI)/Cr(VI) adsorption-reduction. Different analytical techniques were applied to adequately characterize all as-prepared materials to determine the formation of species with the desired morphology and properties. Results revealed that the special chemical structure of MXenes could improve the dispersion of FeS nano-particles and suppress its aggregation. Meanwhile, the adsorption data closely well tailored with the Langmuir isotherm and Pseudo-second-order equation, and the maximum removal efficiencies were 88.5 and 107.2 mg/g for uranium(VI) and chromium(VI). It was also found that the presence of other cations and anions had no obvious influence on removal of U(VI)/Cr(VI), whereas the elimination process was a spontaneous endothermic reaction . More importantly, according to the spectroscopic analysis and DFT calculation , both FeS and surface functional groups on Ti 3 C 2 @FeS-PDA/PEI exhibited strong chemical affinities to the targeted pollutants, while FeS could effectively reduce Uranium(VI) to Uranium(IV) and Chromium(VI) to Chromium(III). This work facilitated the omnidirectional improvement of MXenes-based materials for the de-pollution of practical radionuclide or heavy metals wastewater.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
·
IF 8.6
Xiaojie Zhang,Kangrui Ma,Hong Peng,Yuefa Gong,Yanjun Huang
Simultaneous removal of chromium(VI) oxyanions and heavy metal cations from contaminated water body is of great significance. In this work, a novel and bifunctional sorbent, imidazolium functionalized polysulfone/DTPA-chitosan composite bead (IMPSF/DACS) was successfully constructed by phase inversion method and applied for co-removal of Cr(VI) and Cu(II) from aqueous solutions. The maximum adsorption capacities for Cr(VI) and Cu(II) on IMPSF/DACS in single system at pH 5 were 56.72 and 43.05 mg g −1 , respectively. In binary system, the removal of Cr(VI) could be further enhanced by the presence of Cu(II) due to the electrostatic shielding effect, while Cu(II) sorption was not significantly affected by the coexistence of Cr(VI). Moreover, IMPSF/DACS could simultaneously reduce low concentrations of Cu(II) and Cr(VI) in simulated contaminated lake water below the limit, while also showing good reusability in co-removal of Cr(VI) and Cu(II). The order of inhibitory effect of competing anions on Cr(VI) removal was as follows: H 2 PO 4 − < Cl − < NO 3 − < SO 4 2− , while the competing hardness cations had a little effects on the adsorption of Cu(II), implying that the Cr(VI) removal was mainly depended on the electrostatic attraction between Cr(VI) and imidazolium ions modified on IMPSF/DACS, and Cu(II) uptake was associated with chelation of DACS encapsulated in IMPSF/DACS beads. These assumptions were confirmed by XPS, FTIR and EDS-mapping techniques.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2022
·
IF 8.025
Shichen Wang,Yixuan Liu,Yue Hu,Weibo Shen
Metal-organic frameworks (MOFs) are gradually used since of their huge specific surface area and superior pore structure. However, there are problems such as easy aggregation and difficult separation in water treatment. In this study, we prepared composite microspheres (FMCS-1) by modifying MIL-125-NH 2 with Fe 3 O 4 and chitosan. The structural characterization and performance analysis of the materials showed that the introduction of chitosan effectively prevents the stacking of MOFs. The magnetic test manifested that Fe 3 O 4 solved the problem of the difficult separation of MOFs from water. The removal potential of toxic Cr(VI) was tested by adsorption experiments. The isotherm model indicated that FMCS-1 is a single molecular layer adsorbent with a maximum adsorption capacity of 109.46 mg/g at pH = 2. The adsorption kinetics showed that the adsorption of Cr(VI) by FMCS-1 was chemical adsorption. The acid resistance test demonstrated that FMCS-1 can exist stably in acid solutions. The recycling experiments proved that the adsorbent can be reused and the removal percentage still reaches 50 % after 5 cycles. This work expands the application of MOFs in water treatment and also provides an effective adsorbent for Cr(VI) removal.
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PubMed
高影响因子
APPLIED SURFACE SCIENCE
·
2023
·
IF 6.7
Juan Zhu,Shuang-Bao Li,Bao-Xu Jiang,Yu-Teng Zhang
Zirconium-based metal-organic polyhedra (ZrMOPs) have gained significant attention owing to their well-defined cavities, stability and potential applications. Herein, a novel composite membrane (PDA/ZrT-1-NH 2 /PVDF) was developed by incorporating amino-functionalized ZrMOP (ZrT-1-NH 2 ) into polydopamine (PDA) and trimesoyl chloride (TMC) cross-linking system. Notably, the cationic ZrT-1-NH 2 cages were immobilized onto the membrane surface by a simple vacuum filtration method, which thus endowed the surface positive charge for the membrane. A pre-prepared composite membrane was used to remove Cr(VI) from the wastewater. The effects of pH, contact time, initial Cr(VI) concentration, temperature, coexisting ions competition and reusability were investigated in batch experiments. The results revealed the as-prepared composite membrane exhibited high removal efficiency of 96.6 % for Cr(VI) ions within 5 min. In addition, the adsorption rate was very fast, reaching adsorption equilibrium in less than 30 min. Finally, a possible adsorption mechanism was proposed. The adsorption process was dominated by physical adsorption accompanied by a partial reduction of Cr(VI) to Cr(III).
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LANGMUIR
·
2023
·
IF 3.9
Zishen Lin,Jiang Xu,Aibin Zhu,Chi He,Changzhao Wang,Chunli Zheng
Amorphous zerovalent iron (AZVI) has gained considerable attention due to its remarkable reactivity, but there is limited research on sulfidated amorphous zerovalent iron (SAZVI) and the influence of different sulfur precursors on its reactivity remains unclear. In this study, SAZVI materials with an amorphous structure were synthesized using various sulfur precursors, resulting in significantly increased specific surface area and hydrophobicity compared to AZVI. The Cr(VI) removal efficiency of SAZVI-Na2S, which exhibited the most negative free corrosion potential (−0.82 V) and strongest electron transfer ability, was up to 8.5 times higher than that of AZVI. Correlation analysis revealed that the water contact angle (r = 0.87), free corrosion potential (r = −0.92), and surface Fe(II) proportion (r = 0.98) of the SAZVI samples played crucial roles in Cr(VI) removal. Furthermore, the enhanced elimination ability of SAZVI-Na2S was analyzed, primarily attributed to the adsorption of Cr(VI) by the FeSx shell, followed by the rapid release of internal electrons to reduce Cr(VI) to Cr(III). This process ultimately led to the precipitation of FeCr2O4 and Cr2S3 on the surface of SAZVI-Na2S, resulting in their removal from the water. This study provides insights into the influence of sulfur precursors on the reactivity of SAZVI and offers a new strategy for designing highly active AZVI for efficient Cr(VI) removal.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2022
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IF 6.371
Qiang Gao,Junxi Li,Bin Liu,Chenguang Liu
The rationally designed semiconductor photocatalytic materials have attracted significant attention because of their huge advantages in the use of solar light. Herein, a series of direct Z-scheme heterojunction nanocomposites were synthesized via in situ growth of zinc indium sulfide nanosheets on ceria nanosheets (ZnIn 2 S 4 @CeO 2 ) and employed for effective photodegradation and Cr(VI) reduction. Advanced characterizations such as XPS , EPR spectra, and DFT calculations verified that the formation of direct Z-scheme charges transfer mechanism promoted rapid charge separation and retained strong redox capacity. As a result, the optimized ZnIn 2 S 4 @CeO 2 sample showed significantly promoted photocatalytic removal rates for tetracycline (TC) and Cr(VI) at a 3.7 and 4.5 times enhancement by comparison with the pristine ZnIn 2 S 4 , respectively. Additionally, after four consecutive cyclic tests, the as-synthesized nanocomposite exhibited remarkable photocatalytic activity and stability. The present work provides an integrated engineering strategy for Z-scheme photocatalyst systems with high photocatalytic efficiency and extensive applications.
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Frontiers in Energy Research
·
2022
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IF 3.858
Wang Hongfei,Zhao Xiqiang,Yang Xinfei,Sun Shuang,Wang Wenlong,Mao Yanpeng,Song Zhanlong
In this paper, two types of adsorption materials SA-C-Fe and SA-C-Fe(C) were prepared using bagasse biochar produced by one-step microwave pyrolysis and activation for Cr(VI) removal of wastewater. The adsorption materials were characterized, and Cr(VI) adsorption performance, kinetics and thermodynamics on adsorption materials were studied. Results show that microwave pyrolysis/activation contributes to developed pore structure and abundant active functional groups, resulting in high Cr(VI) adsorption capacities. The optimal preparation conditions for biochar is: microwave power 500 W, ZnCl2/bagasse ratio 2.5:1 and pyrolysis/activation time 15 min, and the specific surface area of biochar is 1,787.64 m2/g. The Cr(VI) adsorption of the two materials is more in line with the pseudo-second-order kinetic model, and the adsorption process is dominated by chemical adsorption. The static removal experiment of Cr(VI) using SA-C-Fe and SA-C-Fe(C) has the best removal effect at pH = 2, and the whole adsorption process is more in line with the Langmuir-Freundlich isotherm model. Calculated by the pseudo-two-order kinetic model and the Langmuir-Freundlich isothermal model, the maximum adsorption rate for Cr(VI) of SA-C-Fe and SA-C-Fe(C) are 211.87 mg/g and 388.92 mg/g, respectively. The removal process is mainly dominated by three mechanisms: electrostatic adsorption, ion exchange and redox reactions. The improvement of Cr(VI) adsorption capacity is attributed to more developed pore structure. The results offer beneficial reference for the application of low-cost carbon-based adsorption materials for pollutants separation, and effectively realize the utilization of bagasse pyrolysis by-products.
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ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2022
·Vol. 30
·期 10
·26889-26900
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IF 5.19
Jiang Chunlu,Zhou Shijia,Li Chang,Yue Fengdie,Zheng Liugen
A ZnCl 2 -modified biochar-supported nanoscale iron sulfide composite (FeS-ZnBC) was successfully prepared to address the easy oxidization of FeS and enhance Cr(VI) removal from water. The material was characterized by SEM, XRD, FTIR, and XPS. The effects of FeS:ZnBC mass ratio, FeS-ZnBC dosage, solution pH, initial Cr(VI) concentration, and reaction time on the adsorption performance were investigated. The results revealed that the optimum adsorption capacity of FeS-ZnBC (FeS:ZnBC = 1:2) for Cr(VI) was 264.03 mg/g at 298 K (pH = 2). A Box-Behnken design (BBD) was applied to optimize the input variables that affected the adsorption of Cr(VI) solution. The results revealed that the highest removal (99.52%) of Cr(VI) solution was achieved with a Cr(VI) initial concentration of 150.59 mg/L, FeS-ZnBC adsorbent dosage of 2 g/L, and solution pH of 2. The sorption kinetics could be interpreted using a pseudo-second-order kinetic model. The isotherms were simulated using the Redlich-Peterson isotherm model, indicating that Cr(VI) removal by the FeS-ZnBC composites was a hybrid chemical reaction-sorption process. The main mechanisms of Cr(VI) removal by FeS-ZnBC were adsorption, chemical reduction, and complexation. This study demonstrated that FeS-ZnBC has potential application prospects in Cr(VI) removal.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2022
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IF 9.136
Jiangli Sun,Jinhang Yang,Jiaxiang Liang,Lingli Tu,Yuejing Bin,Yanping Hou
It is crucial to design efficient photocatalysts for elimination of combined pollutants in wastewater. Herein, the S-scheme Zn 3 In 2 S 6 -BGQDs/AgBr (ZBA) heterojunction was synthesized through co-modification of Zn 3 In 2 S 6 with B-doped graphene quantum dots (BGQDs) and AgBr nanoparticles using solvothermal method for synchronous removals of nitrofurazone (NFZ) and Cr (VI). Characterization results revealed that ZBA showed superior photocatalytic activity than the counterparts. In NFZ-Cr (VI) coexistence environment, removal efficiencies towards NFZ and Cr (VI) were 95.23% and 99.39% using the ZBA photocatalyst within 2 h of visible light irradiation. Results demonstrated that ∙OH, h + and ∙O 2 − played major role for NFZ removal, while mainly e - and ∙O 2 − contributed to Cr (VI) reduction. The S-scheme heterojunction mechanism of ZBA was confirmed by energy band structure analysis, ESR and calculated work function. Possible pathways and mechanisms of NFZ degradation were proposed according the identified intermediates. Besides, the ecotoxicity of intermediates was analyzed. This study advances the development of photocatalytic treatment of combined-polluted wastewater.
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JOURNAL OF MOLECULAR LIQUIDS
·
2022
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IF 6.633
Shiyao Li,Rong Cheng,Jiahao Li,Haobo Hou,Yi Wang,Jiaao Chen,Yuwei Xiang,Min Zhou
The efficient removal of hexavalent chromium from solution is a challenging task, in this paper, the nZVI and nitrogen co-doped magnetic carbon aerogel microsphere composites (nZVI@NCAs) were prepared via the microemulsion polymerization and subsequent carbonization process, and were expected to satisfactory performance in the removal of Cr(VI). From batch experiments, the Cr(VI) removal process by nZVI@NCA900 fitted better with the pseudo-second-order model. The optimal nZVI@NCA900 was superior to that of most magnetic carbon-substrate composites, displaying high Cr(VI) adsorption capacity of 266.79 mg·g −1 at 318 K. Additionally, it was found that Cr(VI) was reduced to the low-toxicity Cr(III) from the results analyzed by XPS, and nZVI@NCA900 exhibited Cr(VI) reduction performance of 33.92% Cr(VI) reduced to Cr(III). The reaction between the nZVI@NCAs and Cr(VI) was pH-dependence, endothermic and spontaneous. Removal mechanisms might involve multiple processes. The nZVI particles on the surface acted as reductants to reduce Cr(VI) to Cr(III) and form Cr(III)/Fe(III) hydroxides to precipitate on nZVI@NCAs. Simulation results by DFT prove that N is an active site and show positive effect in the adsorption system. N atoms were used as active sites to stabilize the interaction with Cr(VI) via adsorption attributed to electrostatic and act as electron donors for reduction of Cr(VI). The nZVI particles encapsulated by carbon aerogels could provide magnetic stability after acid reaction, which was beneficial to the separation of adsorbents after reaction and reuse for many cycles. These results provide a new view for developing magnetic carbon materials to remove Cr(VI) from contaminated water.
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