ENVIRONMENTAL RESEARCH
·
2022
·
IF 8.431
Shuoqi Ren,Yuchen Wang,Zijian Han,Qiwei Zhang,Chongwei Cui
A highly efficient absorbent was developed in this study by modifying polydopamine film on Mg–Al layered double hydroxide (PDA/MgAl-LDH) to remove Cr(VI) from wastewater. The characterization results showed that the polydopamine film was successfully coated on the MgAl-LDH surface. The preparation ratio, pH, and adsorbent dosage influencing absorption by PDA/MgAl-LDH were systematically investigated. The absorption capacity of Cr(VI) by PDA/MgAl-LDH was 87 mg/g. The equilibrium adsorption isotherm of PDA/MgAl-LDH was in good agreement with that of the Langmuir model. Therefore, the pseudo-second-order kinetic model is suitable for describing adsorption kinetics. The interaction between PDA and Cr(VI) and Cr(III) was investigated using density generalized function theory (DFT), which demonstrated that the PDA amino group could provide electrons for Cr(VI) reduction. Hydrogen and covalent bonding were dominant during the chemisorption process of PDA absorbing Cr(VI), the nitrogen of 5,6-dihydroxyindole was the primary active site for absorbing Cr(III), and electrostatic attraction was mainly responsible for Cr(III) absorption. Therefore, PDA/MgAl-LDH has the potential to adsorb and remove Cr(VI) from wastewater.
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Frontiers in Bioengineering and Biotechnology
·
2022
·
IF 6.064
Xie Dan,Wang Ruimeng,Fu Jinghao,Zhao Zhongxing,Li Min
Surface-enhanced Raman scattering (SERS) is an important and powerful analytical technique in chemical and biochemical analyses. Metal–organic frameworks (MOFs) can effectively capture volatile organic compounds (VOCs) with high adsorption capacity and fast kinetics, and the local surface plasmon resonance characteristics of gold nanoparticles can quickly and effectively distinguish different VOCs by SERS. Combining both, we designed a novel SERS substrate based on embedding gold nanoparticles (AuNPs) within MIL-101(Cr) for the recognition of various VOCs in the gaseous phase. Occupying of AuNPs inside MIL-101(Cr) increased the micropore-specific surface area of AuNPs@MIL-101(Cr), which enabled AuNPs@MIL-101(Cr) to absorb more toluene molecules and consequently realized its high detection sensitivity. The detection limits for toluene, 4-ethylbenzaldehyde, and formaldehyde were down to 6, 5, and 75, ppm respectively. Moreover, this substrate could be used for detecting different VOCs simultaneously. Finally, we discussed the enhancement of AuNPs outside and inside MIL-101(Cr) on the Raman signal.
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JOURNAL OF HAZARDOUS MATERIALS
·
2021
·
IF 10.588
Renji Zheng,Jing Li,Runliang Zhu,Ranhao Wang,Xuezhen Feng,Zhijie Chen,Wenfei Wei,Dazhong Yang,Hong Chen
Wastewater with complex compositions of both heavy metals and organic pollutants is of critical environmental and socioeconomic threat worldwide, which urgently requires feasible remediation technologies to target this challenge. In this study, natural chalcopyrite (CuFeS 2 , NCP), the most abundant copper-based mineral in the Earth's crust , has been discovered to be a heterogeneous catalyst that can activate peroxydisulfate (PDS) for the simultaneous degradation of organic pollutant Rhodamine B (RhB) and reduction of hexavalent chromium (Cr(VI)). Batch experimental results indicate that both RhB and Cr(VI) could be simultaneously removed under a near-neutral condition in NCP/PDS combined system. The radicals SO 4 •− and • OH generated from PDS activation are the main oxidative species detected by electron paramagnetic resonance (EPR) spectroscopy. SO 4 •− acted as a predominant role in RhB degradation, while Cr(VI) reduction is mainly attributed to the oxidization of S 2− and S 2 2− species on NCP surface, as well as the photoreduction performance of NCP, which could be enhanced by the intermediates generated from RhB degradation. Density functional theory (DFT) calculation results disclose that Fe is the critical catalytic site for PDS activation. This work demonstrates a user-friendly strategy for remediation of complex wastewater containing both heavy metal and organic pollutants by combining photoreduction and advanced oxidation processes (AOPs) with natural minerals. It paves a way for wastewater treatment by utilizing low-cost natural abundant minerals as catalysts.
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CERAMICS INTERNATIONAL
·
2022
·
IF 5.532
Hongfei Yin,Chunyu Yuan,Huijun Lv,Kaiyue Zhang,Xue Chen,Yongzheng Zhang
Environmental crisis aroused from the Cr(VI)-containing wastewater has received much attention, due to the cancer-causing and mutagenic feature of Cr(VI). Photocatalytic technology has been considered to be a favorable contestant for coping with Cr(VI)-containing effluent. In this study, Ti 3 C 2 MXene/Zn 3 In 2 S 6 Schottky junctions with different content of Ti 3 C 2 MXene were prepared for Cr(VI) photoreduction. The inherent physical and photoelectrochemical characters of the obtained Ti 3 C 2 MXene/Zn 3 In 2 S 6 Schottky junctions were fully characterized. Compared with the pure Zn 3 In 2 S 6 , all the nanocomposites showed enhanced photocatalytic performance, the apparent kinetic constant of the optimized sample was 3.17 times the height of the Zn 3 In 2 S 6 . The improved photoreduction performance largely originated from the effectual separation and transfer of the photoexcited charge carriers. In the meantime, the deleterious role of superoxide radicals for Cr(VI) photoreduction was confirmed. It is anticipated this research can deliver a new-fangled vision for constructing efficient photocatalyst for Cr(VI) photoreduction.
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Water Science and Engineering
·
2021
·
IF 0
Li Yin,Na Mi,You-ru Yao,Jing Li,Yong Zhang,Shao-gui Yang,Huan He,Xin Hu,Shi-yin Li,Li-xiao Ni
Ferrous sulfide (FeS) nanoparticles constitute an effective hexavalent chromium (Cr(VI)) treatment reagent. However, FeS nanoparticles aggregate easily, significantly limiting their engineering applicability. To overcome this shortcoming and further improve Cr(VI) removal efficiency, this study used tannic acid (TA) to modify FeS nanoparticles. The results demonstrated that TA-modified FeS nanoparticles, TA-nano-FeS, had a significantly reduced tendency to agglomerate, and maintained particle diameters of 10–100 nm, which were much shorter than diameters of FeS nanoparticles. In addition, TA-nano-FeS could combine the surface-active functional groups of TA. The maximum removal capacity of TA-nano-FeS was 381.04 mg/g, which was 2.92 and 1.83 times higher than those of TA and nano-FeS, respectively. Furthermore, the acidic condition was more beneficial for Cr(VI) removal, and the coexisting cations (Ca 2+ and Mg 2+ ) slightly decreased the removal efficiency of Cr(VI). Adsorption, reduction, and co-precipitation were the removal mechanisms, and the reaction products included FeCr 2 O 4 , Cr 2 O 3 , Fe 2 O 3 , Cr(OH) 3 , and S 8 . The results provided valuable information for the practical application of TA-nano-FeS in Cr(VI) removal.
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Journal of Environmental Chemical Engineering
·
2021
·
IF 5.909
Xian Zeng,Yuchen Wang,Xinyi He,Caocong Liu,Xi Wang,Xinpeng Wang
Being one of the most toxic pollutants commonly present in wastewater as soluble hexavalent chromium (Cr(VI)) specie, its concomitant adsorption and chemical reduction to relatively insoluble and less poisonous Cr(III) would be an effective strategy for remediation of Cr-polluted water. As such, a novel MXene-polyelectrolyte nanocomposite was typically synthesized for enhanced Cr(VI) removal. In detail, we applied polyethylenimine (PEI) to modify the Ti 3 C 2 T x surfaces and synthesized Ti 3 C 2 T x /PEI nanocomposites. The as-prepared composites were characterized by various methods such as SEM-EDX, N 2 sorption-desorption isotherm, XRD, FTIR, and XPS. Further, the Ti 3 C 2 T x /PEI was used to adsorb Cr(VI) for clarifying the kinetics, isotherms, and the effects of solution pH and coexisting ions on Cr(VI) removal by batch experiments. Our results show that coating of Ti 3 C 2 T x nanosheets with PEI regulates surface charge of the as-synthesized adsorbent and creates it with a three-dimensional network, allowing the fast electrostatic adsorption of Cr(VI) anions to positively charged surface over wide pH range of 1–10 and promoting to achieve improved removal capacity maximum up to 186.5 mg/g. The Cr(VI) adsorption data were well fitted by the pseudo-second-order kinetic and Langmuir isotherm models. In addition, Ti 3 C 2 T x /PEI also exhibits excellent selectivity for Cr(VI) anions over competing ones such as NO 3 − , Cl − , ClO 4 − , and SO 4 2− . Time-dependent reaction routes of Ti 3 C 2 T x /PEI nanocomposite toward Cr(VI) was studied by XPS, which confirmed the slow reduction of all sorbed Cr(VI) to Cr(III) in the dozens of hours and final in-situ Cr(III) immobilization, clarifying the sorption-reduction mechanism for Cr(VI) elimination. All these results suggest that Ti 3 C 2 T x /PEI nanocomposite prepared by reported surface-modification approach available for developing other functionalized adsorbents, may be a potential candidate for decontamination of Cr(VI)-polluted wastewater.
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FUEL PROCESSING TECHNOLOGY
·
2021
·
IF 7.033
Yilun Sun,Meng Huang,Jingpeng Li,Zhiyuan Wang,Jianxin Zhou
The coke in the coils has a serious impact on the long-term and stable operation of the ethylene plant . Inhibiting coking of the cracking furnace is an important issue. In this paper, the Cr/CeO 2 coatings were prepared on the surface of 310S stainless steel by high-velocity oxygen-fuel (HVOF) spraying. The anti-coking performances of the bare 310S specimen and the Cr/CeO 2 coatings were tested by using the pyrolysis of naphtha . The results show that the coating with the thickness of 10–15 μm and a very small number of pores was built up by the obviously deformed splats and the coating/substrate interface is jagged bond. The white area on the surface of Cr/CeO 2 coatings mainly includes CeO 2 . However, the gray area is made of Cr or Cr 2 O 3 . Compared with the bare 310S specimen, the coking inhibition rates of coatings are 48.7%, 58.9%, 76.1% and 88.9% when the ratio of Cr and CeO 2 powder is 19:1, 9:1, 4:1 and 3:2, respectively. With increasing the relative ratio of CeO 2 , more white areas without coke are exposed. The CeO 2 surface can not only inhibit catalytic coking, but also promote the reaction of water vapor and coke.
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Sustainability
·
2021
·Vol. 14
·期 1
·21
·
IF 3.251
Shuangshuang Zhang,Wenhui Zhang,Yazhen Wan
To remedy the widespread chromium (Cr) pollution in the environment, this study mainly used the ultrasonic-assisted co-precipitation and precipitation methods to prepare FeS-modified Fe-Al-layered double hydroxide (FeS/LDH) composite material. The experimental results showed that FeS/LDH has higher removal efficiency of Cr in aqueous solution and stronger anti-interference ability than unmodified LDH. Under the same reaction conditions, the removal efficiency of total Cr(Cr(T)) using LDH was 34.85%, and the removal efficiency of Cr(VI) was 46.76%. For FeS/LDH, the removal efficiency of Cr(T) and Cr(VI) reached 99.57% and 100%, respectively. The restoration of Cr(T) and Cr(VI) by FeS/LDH satisfied the Langmuir adsorption isotherm. The maximum adsorption capacity of Cr(T) and Cr(VI) achieved 102.9 mg/g and 147.7 mg/g. The efficient removal of Cr by FeS/LDH was mainly based on the triple synergistic effect of anion exchange between Cr(VI) and interlayer anions, redox of Cr(VI) with Fe2+and S2−, and co-precipitation of Fe3+and Cr3+.Keywords:chromium;FeS/LDH;double reduction;anti-interference;co-precipitation
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SENSORS AND ACTUATORS B-CHEMICAL
·
2021
·
IF 7.46
Cuijuan Wang,Ming Shang,Haiyan Wei,Mengping Zhang,Wei Zou,Xiao Meng,Wenwen Chen,Hua Shao,Yongchao Lai
Hexavalent chromium (Cr(VI)), a highly toxic heavy metal ion , poses a serious threat to human health, and the demand of rapid detection still on-going. Herein, we propose a surface-enhanced Raman spectroscopy (SERS)-based method for rapid and cost-effective quantification of Cr(VI) in aqueous solutions with direct signal of Cr(VI) rather than indirect signals of Raman reporter molecules exploited in previous studies. This method demonstrates high sensitivity (the detection limit of 0.72 ppb), high reproducibility (the batch-to-batch variation was less than 10 %), and excellent selectivity. The results of this proposed method are fairly in good agreement (R 2 = 0.991) with those of the UV colorimetric method promulgated by the United States Environmental Protection Agency (USEPA). We demonstrated the potential of our novel method for practical application in determining Cr(VI) concentrations in drinking and environmental water samples, in which adequate recovery, and high interference resistance were observed. This method has the advantages of being faster and suitable for on-site inspection as no pretreatment process is required and the equipment is portable. The excellent performance promises a great prospective toward a rapid, reliable, and on-site detection for Cr(VI).
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Journal of the Taiwan Institute of Chemical Engineers
·
2021
·
IF 5.876
Anqi Sun,Ying Wu,Zhenjiang He,Peng Bai,Jiafei Lyu,Xianghai Guo
The flexible metal-organic framework MIL-53(Cr) has been demonstrated to be an efficient adsorbent for liquid phase adsorption and separation, while the effect of this attractive “breathing effect” on its performance remains uncertain. In this research, by increasing the amount of introduced water, MIL-53(Cr) first shrank into a narrow pore form through bound water and then reopened due to the introduction of free water. Using MIL-53(Cr) with diverse amounts of water as an adsorbent, the liquid-phase adsorption and separation of C8 aromatics, including o -xylene (OX), p -xylene (PX), m -xylene (MX) and ethylbenzene (EB), was manipulated by the pre-adsorbed water in MIL-53(Cr). Pre-adsorbing water in MIL-53(Cr) induced a preference reversal between MX and PX, where dry samples preferentially adsorbed MX, while high-water-addition samples preferred PX instead. In addition, the reopened MIL-53(Cr) with high water addition hardly adsorbed EB, thereby increasing the selectivity of xylene isomers to EB. A longer equilibrium time was observed on MIL-53(Cr) with high water addition, during which the adsorption preference shifted from OX to MX to PX. Further molecular simulation provided a microscopic explanation that water molecules in the pores tended to package around MX and EB, hindering their interaction with frameworks or other adsorbates.
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TALANTA
·
2021
·
IF 6.057
Hui-Min Zhai,Bin Ji,Shan-Shan Tian,Fang Fang,Shuang Zhao,Zhi-Yong Wu
This work presents a new method of Cr speciation analysis based on micro sample pretreatment with a paper-based analytical device (PAD). By using electrokinetic separation and stacking on the PAD, Cr (VI) and Cr (III) can be separated and the recovered to achieve speciation analysis without have to be subjected to subtraction treatment. The separation and recovery properties of Cr (VI) and Cr (III) were characterized and optimized by UV–Vis spectrophotometry , with which the LOQ of 19.0 μg L −1 and 28.7 μg L −1 , and the recoveries of 88–108% and 90–110%, were obtained for Cr (VI) and Cr (III), respectively. In addition, direct analysis of Cr (VI)/Cr (III) from an electroplating wastewater sample was also demonstrated with this method combined with atomic spectroscopy (GF-AAS and ICP-OES). This sample pretreatment method is fast, cheap and easy to be used. Combined with the high sensitivity and elemental selectivity of atomic spectroscopy and mass spectrometry, this PAD sample pretreatment method could be a compensation to their lack in speciation discrimination, and may play an important role in the speciation analysis of Cr.
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JOURNAL OF APPLIED POLYMER SCIENCE
·
2021
·Vol. 138
·期 27
·50642
·
IF 3.125
Zhimei Wei,Shouyu Zhang,Xiaojun Wang,Shengru Long,Jie Yang
Cr (VI) is a highly toxic pollutant to humans, to achieve high adsorption capacity, easy recovery, and good reusability, polyethersulfone/polydopamine (PES/PDA) ultrafine fibers were prepared successfully. A series of preparing effect factors were investigated systematically and the optimum one is 8.5 pH value at room temperature and 2 g/L dopamine concentration. And then they were used as an adsorbent for the removal of Cr (VI) ions from wastewater. The effect factors pH, the adsorbent dosage, and time were discussed on Cr (VI) adsorption process and the Cr (VI) adsorption behavior was investigated. It is found that the maximum Cr (VI) adsorption capacity is 115.2 ± 4.8 mg/g at pH = 3 using 0.06 g PES/PDA with 80 mins. The Cr (VI) adsorption process followed the pseudo-second-order model (r 2 ≥ 0.99) and adsorption isotherms were fitted to the Langmuir model (R 2 ≥ 0.999). Furthermore, the Cr (VI) adsorption mechanism was supposed according to the X-ray photoelectron spectroscopic results. Finally, PES/PDA ultrafine fibers were considered to be a promising adsorbent with good stability (decomposing temperature, 356°C), high adsorption efficiency (112.1 ± 2.5 mg/g), and good reusability (three times) on the coexistence of anions and the actual industry wastewater environment.
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