ACS Applied Nano Materials
·
2023
·
IF 5.9
Dongmei Jia,Yuejin Li,Huamin Cai,Yongzheng Duan,Jing Li,Chen Ling
Capture of heavy metal ions from aqueous solutions is a critical but challenging step in environmental treatment. In this work, NH2-MIL-101(Fe) nanoparticles were synthesized by simple solvothermal methods and applied to capture Cr(VI) anions from aqueous solutions. The results revealed that NH2-MIL-101(Fe) exhibited a high capture capacity (375.2 mg g–1) and an ultrafast capture rate (4 min reaching equilibrium). The competitive effects of coexisting ions such as Cl–, HCO3–, PO43–, Cd2+, Ca2+, and Cu2+ on Cr(VI) are very weak, suggesting that the adsorption selectivity significantly enhanced by loading amino groups on MIL-101(Fe). Density functional theory (DFT) calculation was performed to better understand the adsorption mechanism of Cr(VI), showing that the amino groups could increase the adsorption energy of Cr(VI) for enhancing the adsorption capacity. Based on powder X-ray diffraction, X-ray photoelectron spectroscopy, and DFT calculations, the Cr(VI) capture mechanism by NH2-MIL-101(Fe) nanoparticles was a combination of coordination between Fe and Cr(VI), electrostatic interaction between Cr2O72– and the protonated amino group, and reduction of Cr(VI) to Cr(III).
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2019
·
IF 5.107
Yaoqiang Wang,Ziheng Cui,Gang Xiao,Yilin Zhao,Yu Jin,Zishuai Wang,Haijia Su,Tianwei Tan
To study the applicability and mechanism of the visible-light-driven photo-reduction of Cr(VI) is important since it will elucidate the chromium cycle in natural circumstances, and since this reduction reaction is important in treating wastewater contaminated by Cr(VI). Herein, we conducted an in-depth mechanism study for this process using formic acid as electron donor. The positive dependence of the Cr(VI) conversion on the incident light intensity and the good match between the apparent quantum yield (0.0039–0.39%) and the light absorption spectrum (550–365 nm) suggests a light-induced mechanism. The light-induced charge transfer occurs through the ligand-to-metal charge transfer state of the complex which forms between one dichromate molecule and two formic acid molecules through symmetrical or asymmetrical configuration as demonstrated by DFT simulation. EPR analysis further proves that this reaction occurs through a stepwise process with Cr(V) and Cr(IV) as the intermediates. The practical use of this photochemical procedure with broad electron donor scope and wide pH, reaction temperature, and initial Cr(VI) concentration ranges, is proven by the application potential evaluation. The efficient reduction of Cr(VI) by formic acid under sunlight further proves the applicability of this photochemical procedure for the treatment of Cr(VI) contaminated wastewater. Development of the present study into both the treatment of Cr(VI) contaminated wastewater, and other visible-light-driven photo-redox reactions between metals and organics are the subject of further research and results can be expected in the near future.
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ENVIRONMENTAL RESEARCH
·
2019
·
IF 5.026
Misganaw Alemu Zeleke,Dong-Hau Kuo
The oxy-sulfide based V 2 O 5 @(In,Ga) 2 (O,S) 3 nanocomposite catalyst, at different weight percentages of V 2 O 5 , was successfully synthesized via a simplistic procedural route for the detoxification of hazardous Cr(VI). The two pure catalysts were intimately allied and used for visible light-driven reduction of hazardous Cr(VI). The nanocomposite catalysts were characterized to observe the effects of V 2 O 5 on crystal phase, morphology, light absorption , catalytic activity , and electrical properties. Compared to all, 40% V 2 O 5 loaded nanocomposite catalyst, designated as VOS-2, exhibited the best-reducing capability. It completely reduced toxic Cr(VI) at 2 min under visible light illumination. From the kinetics, it was found that the rate constant of the nanocomposite catalyst was improved by a factor of 3.6 compared to the host nanoflower catalyst. The plausible mechanism of charge transfer process across the interfacial region indicates the diminished recombination probability of photogenerated charge carriers. Therefore, the nanocomposite catalyst is promising for enhanced reduction of Cr(VI) in the Cr-based industrial activities, which is significantly relevant for environmental remediation.
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ACS Sustainable Chemistry & Engineering
·
2019
·
IF 6.97
Yangmei Ren,Lan Mei,Yingchun Gu,Na Zhao,Yuelong Wang,Rangrang Fan,Aiping Tong,Haifeng Chen,Hui Yang,Bo Han,Gang Guo
Poly(lactic acid) (PLA) stereocomplex crystallite (SC)-based electrospun nanofibers were fabricated via annealing the as-spun membranes at 100 °C for 1 h. The heat-treated nanofibers exhibit enhanced mechanical properties and thermal resistance due to the existence of SCs, which restricts the lactide chain mobility. The formation of SCs increases the intermolecular forces between l-lactide and d-lactide segments, resulting in almost 2 times higher tensile strength (8.52 ± 0.29 MPa) and 3 times higher Young’s modulus (285.48 ± 1.19 MPa) than that of the untreated membranes, which is benefitting for wider applications. Additionally, a green absorbent named HTA synthesized from tannic acid and hexamethylenediamine was introduced into the nanofibers, giving the membrane richer functions. Based on the abundant reactive functional groups on the surface, small pore size and large surface area-to-volume ratio of the nanofibers, the HTA containing membranes exhibited excellent performance in adsorbing heavy metal ions and inhibiting bacterial growth. This bifunctional membrane showed reusability for 4 cycles with retaining good removal capability of Cr(VI) and antibacterial effects. Furthermore, Cr(VI) was found to be adsorbed and converted to less toxic Cr(III) during the adsorption process, and bacteria, such as Escherichia coli and Staphylococcus aureus, were captured and broken on the surface of the nanofibers. In this study, we focused on a novel eco-friendly bifunctional SC-based PLA nanofiber to repeatedly adsorb metal ions and capture bacteria, and thus it is expected to have potential in various fields in the future.
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JOURNAL OF HAZARDOUS MATERIALS
·
2018
·
IF 6.434
Jianhao Qiu,Xiong-Fei Zhang,Xingguang Zhang,Yi Feng,Yuxin Li,Lvye Yang,Haiqiang Lu,Jianfeng Yao
A novel and highly efficient photocatalyst of Cd 0.5 Zn 0.5 S@ZIF-8 nanocomposite has been developed by a facile self-assembly strategy. This is the first report on the application of Cd x Zn 1−x S and metal-organic framework (MOF) nanocomposite as photocatalysts for the reduction of Cr(VI). The resulting Cd 0.5 Zn 0.5 S@ZIF-8 exhibited higher photocatalytic activity than that of pristine Cd 0.5 Zn 0.5 S and ZIF-8. Particularly, the CZS@Z60 composite with 60 wt% of ZIF-8 exhibited a photocatalytic activity that is about 1.6 times as high as that of Cd 0.5 Zn 0.5 S. The dominant reason for the improved photocatalytic reduction potential is proved to be the newly-formed interfacial S Zn bonds that firmly connect Cd 0.5 Zn 0.5 S and ZIF-8 and substantially improve the separation efficiency of photo-excited electrons and holes. The newly-formed chemical bonds are confirmed by XPS analyses, and the prolonged lifetime of photo-excited electrons is evidenced by the electrochemical measurement of photocurrent, which shows that the photocurrent on Cd 0.5 Zn 0.5 S@ZIF-8 is much higher than that of Cd 0.5 Zn 0.5 S and ZIF-8. This study clearly demonstrates that the MOF-based composite nanomaterials hold great promises for applications in the field of environmental remediation and for design of novel photocatalytic materials.
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Frontiers in Chemistry
·
2018
·
IF 4.155
Wei Yanke,Mei Lefu,Li Rui,Liu Meng,Lv Guocheng,Weng Jianle,Liao Libing,Li Zhaohui,Lu Lin
Hexavalent chromium species, Cr(VI), which can activate teratogenic processes, disturb DNA synthesis and induce mutagenic changes resulting in malignant tumors. The detection and quantification of Cr(VI) is very necessary. One of the rapid and simple methods for contaminant analysis is fluorescence detection using organic dye molecules. Its application is limited owing to concentration quenching due to aggregation of fluorescent molecules. In this study, we successfully intercalated 7-amino-4-methylcoumarin (AMC) into the interlayer space of montmorillonite (MMT), significantly inhibited fluorescence quenching. Due to enhanced fluorescence property, the composite was fabricated into a film with chitosan to detect Cr(VI) in water. Cr(VI) can be detected in aqueous solution by instruments excellent, ranging from 0.005 to 100 mM with a detection limit of 5 μM.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2018
·
IF 3.909
A.M. Omer,R.E. Khalifa,Zhaohong Hu,Hong Zhang,Chao Liu,Xiao-kun Ouyang
In this study, an innovative adsorbent based on tetraethylenepentamine (TEPA) functionalized alginate (Alg) beads (TEPA-Alg) was developed for the adsorptive removal of Cr (VI) from aqueous solutions. Chemical modification of alginate surface was carried out using p-benzoquinone (PBQ) as a coupling agent followed by functionalization with TEPA. The prepared functionalized beads were characterized using FTIR, TGA, SEM, and XPS tools. Results showed that the ion exchange capacity (IEC) significantly increased from 6.34 to 10.32 m eq g −1 with increasing TEPA concentration up to 0.05 M. Furthermore, removal (%) of Cr (VI) increased gradually from 38 to 86% with rising TEPA concentration from 0.0125 M to 0.05 M. While only 22% was recorded using native alginate beads. The gained equilibrium data were fitted to Langmuir isotherm model with maximum adsorption capacity ~ 77 mg/g and the adsorption kinetics were well-expressed by pseudo-first-order model. Reusability studies showed good adsorption properties after 5 consecutive cycles. Results achieved by this study imply that the prepared functionalized TEPA-Alg beads could be efficiently utilized for the removing Cr (VI) ions from their aqueous solutions.
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CHEMICAL ENGINEERING JOURNAL
·
2018
·
IF 6.735
Shixia Chen,Yifeng Huang,Xinxin Han,Zeliang Wu,Cen Lai,Jun Wang,Qiang Deng,Zheling Zeng,Shuguang Deng
Layered double hydroxides (LDHs) are currently attracting intense research interests as pollutant adsorbent due to its low cost, non-toxicity, structure amenability and anion exchange capability. Herein, 3-dimensional (3D) flower-like Ni/Al LDH were prepared to decorate H 3 PO 4 activated biomass-derived porous carbons (PAB) via a facile and green hydrothermal method. The as-synthesized nanocomposites (Ni/Al@PAB) displayed favorable removal performance towards both Cr(VI) and methyl orange (MO) from aqueous solution due to the inherited excellent Cr(VI) removal ability from PAB and MO removal ability from Ni/Al LDH. In single-component removal system, the maximum adsorption capacity of 271.5 and 412.8 mg/g for Cr(VI) and MO were achieved on Ni/Al@PAB, respectively. Remarkably, the removal capacity of Cr(VI) and MO both increased in the Cr(VI) MO binary system due to the synergistic effect including, (i) additional adsorption sites of N-containing groups from MO, (ii) electrostatic interactions by the reduced Cr(III), and (iii) mutual thermal compensation in the binary system. This work paved the way for designing novel LDHs-decorated porous carbon adsorbents and revealed that the acicular Ni/Al LDH decorated PAB could be applied as efficient and simultaneous adsorbent for coexisting toxic pollutants situations.
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2017
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IF 9.446
Yaxi Zhang,Mengjiao Xu,Hao Li,Hao Ge,Zhenfeng Bian
The photocatalytic reduction efficiency of hexavalent chromium (Cr 2 O 7 2− (Cr(VI)) is suffering from high recombination of photoinduced charges, poor adsorption capacity of Cr(VI), and slow desorption of product trivalent chromium (Cr 3+ (Cr(III))) from photocatalyst surface. In this work, carbon dots (CDs) was coupled with TiO 2 mesocrystals (MT), where CDs displayed both the electron collectors and the active sites. During photoreduction of Cr(VI), the as-prepared CD/MT exhibited activity about 5.4 times higher than the pure TiO 2 mesocrystals. The positive charges on the CD/MT surface favored the selective adsorption of Cr(VI) and rapid desorption of Cr(III), which has an obvious promotion on the photocatalytic reduction of Cr(VI) and retention of photoreduction activity. Meanwhile, the CDs coupled on TiO 2 mesocrystals facilitated the separation of photogenerated charges. This work provides a simple and effective adsorption-photoreduction-desorption mechanism for the photocatalytic reduction of Cr(VI).
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MICROCHEMICAL JOURNAL
·
2024
·
IF 4.9
Xuanqi Hao,Xiao Zhang,Jianrong Wang,Chenchen Liu,Chuanhao Li,Ping Yang
To create fluorescent sensors for Cr (VI) and l-arginine detection, blue-emitting carbon dots (CDs, named as M-CDs) were prepared via a solvothermal synthesis by using m-phenylenediamine. The introduction of sulfuric acid changed the blue-emitting of CDs into green-emitting (named as S-CDs), in which the photoluminescence (PL) peak wavelengths of samples M-CDs and S-CDs were 450 and 540 nm, while their PL efficiencies were 21.7 and 84.2 % respectively. Sulfuric acid resulted in the average fluorescent lifetime of the CDs was prolonged into 8.19 from 4.65 ns. The photo and thermal stable tests demonstrated that theses CDs revealed excellent stability. Meanwhile, CDs flexible films with bright blue- and green-emitting were prepared utilizing the favorable solubility of CDs in polar solvents. Mono-dispersed CDs as luminescent materials demonstrated it promising prospects in luminescent devices field. Furthermore, M-CDs exhibited excellent selectivity towards Cr(VI) and l-arginine. The detected limit (0.86 μM for Cr(VI) and 0.43 μM for l-arginine) was determined by assessing the response of M-CDs to various concentrations of Cr(VI) ion and l-arginine solutions. These bright CDs revealed great potential for accurate detection of Cr(VI) and l-arginine.
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CHEMICAL ENGINEERING JOURNAL
·
2025
·
IF 13.2
Yulong Xiang,Xinbin Ji,Xiaoli Dong,Yu Wang,Nan Zheng,Chundong Liu,Menglin Wang,Chumin Yan
Photoreduction of toxic Cr(VI) in wastewater to less toxic Cr(III) presents an effective approach to address the environmental issues. Nevertheless, the photocatalytic performance of these photocatalysts is severely constrained by their narrow light absorption range and the rapid recombination of photo-generated electrons and holes. Herein, DUT-67/Fe 2 O 3 heterojunction photocatalysts were prepared by a simple mechanical grinding method. The formation of DUT-67/Fe 2 O 3 heterostructures not only increased the specific surface area and light absorption range, but also improved the separation of photogenerated charge carriers. Compared to the pristine DUT-67, DUT-67/Fe 2 O 3 exhibited significantly improved photocatalytic performance in the reduction of Cr(VI), achieving a reduction efficiency of up to 94 % within 40 min. Active species trapping experiments identified that electrons served as the primary species in the photocatalytic process. Coupled with electron spin resonance and density functional theory (DFT) calculations, a comprehensive mechanism for the photocatalytic reduction of Cr(VI) by DUT-67/Fe 2 O 3 Z-scheme heterojunction was proposed. This work offers new insights into the underlying mechanisms involving in the interfacial charge transfer and Cr(VI) photoreduction processes.
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RESEARCH ON CHEMICAL INTERMEDIATES
·
2017
·Vol. 43
·期 9
·5217-5228
·
IF 1.369
Qin Na,Jing Kaiqiang,Chen Rui,Xiong Jinhua,Liang Ruowen,Li Zhaohui,Wu Ling
Abstract SnS 2 /SnO 2 nanocomposites have been successfully prepared via a hydrothermal method using electrospun SnO 2 nanotubes as both substrates and reactants. The ratios of the nanocomposites are controlled by varying the concentration of thioacetamide during the solvothermal synthesis processes. The as-prepared SnS 2 /SnO 2 nanocomposites exhibit considerable improvement on the photocatalytic activities for the reduction of aqueous Cr(VI) under visible light irradiation. Their photoactivities are also much higher than that of SnS 2 nanoplates and a physical mixture of SnO 2 and SnS 2 . In particular, the SnS 2 /SnO 2 -B sample exhibits the highest photocatalytic activity. After visible light irradiation for 60 min, the reduction rate has reached about 100%. The photoelectrochemical analyses further show that the high photocatalytic activity of the SnS 2 /SnO 2 -B sample can be ascribed to the unique structural features and the intimate interfacial contact between SnS 2 and SnO 2 , which is more effective separation of the photo-generated carriers. Graphical Abstract
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