CARBOHYDRATE POLYMERS
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2019
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IF 6.044
Tao Hu,Qiang Liu,Qinze Liu,Yang Wu,Congde Qiao,Jinshui Yao
Green composite adsorbent with low cost and high efficiency towards toxic Cr(VI) removal from the polluted water has a broad application prospect. In this work, a mussel-inspired Cr-adsorbent namely poly(catechol tetraethylenepentamine-p-phenylenediamine)@as-prepared cellulose (PAC@AC) is successful fabricated via catechol-amine copolymer adhering onto as-prepared cellulose (AC). The detailed characterizations of product are run with SEM, FT-IR, TGA , XRD, EDS and XPS analysis. Many factors are investigated to affect the adsorption of Cr(VI) by PCA@AC, including ratio of AC to PCA, adsorbent dosage, contact time, initial Cr(VI) concentration, pH, temperature and exterior ions. The maximum adsorption capacity of PCA@AC for Cr (VI) is obtained by 507.61 mg/g at 30°C using Langmuir model, which is very higher than the pure AC. The removal ability of PCA@AC is ascribed to the electrostatic interaction and reduction reaction of Cr(VI) to Cr(III) during the adsorption process. In addition, the adsorption process is spontaneous and endothermic, not require any external energy. The composite adsorbent (PCA@AC) has great potential for Cr(VI)-wastewater purification with an excellent chelating ability.
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SEPARATION AND PURIFICATION TECHNOLOGY
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2019
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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
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2019
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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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RSC Advances
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2018
·Vol. 8
·期 71
·41003-41011
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IF 2.936
Wen Bing Wu,Sun Xue,Jian Hua Chen,Xiao Li
Membrane separation technologies have great promising potential for applications in several industries. Metal–organic frameworks (MOFs), for their large surface areas, low framework densities, transition-metal ions in the skeleton and high pore volumes relative to other porous matrices, have great potential for the removal of sulfur from gasoline with high efficiency. In the present study, a novel porous membrane adsorbent MIL-101(Cr)/SA was prepared by immobilizing MIL-101(Cr) onto sodium alginate (SA) matrix, which can combine the size/shape selectivity of MIL-101(Cr) with the processability and mechanical stability of SA polymer. The physico-chemical properties of MIL-101(Cr)/SA were investigated by FT-IR, SEM, BET, XRD and EDX methods. To investigate the effects of some important factors on the adsorption behavior for thiophene, a batch of experiments were performed by changing the concentration of porogen polyethylene glycol in the MIL-101(Cr)/SA, solution temperature, initial thiophene concentration and contact time. Meanwhile, benzothiophene, thiophene and 3-methyl thiophene were used to test the selectivity of MIL-101(Cr)/SA. The MIL-101(Cr)/SA showed an excellent uptake capacity of 671 mg g−1 under the optimal adsorption conditions. Selectivity testing indicated that the uptake capacity of MIL-101(Cr)/SA follows the order of benzothiophene > thiophene > 3-methyl thiophene. Kinetics experiments indicated the pseudo-second-order model displayed good correlation with adsorption kinetics data. The Crank model showed that the intraparticle solute diffusion is the rate-controlling adsorption step. Regeneration experiment result shows that the prepared MIL-101(Cr)/SA has excellent adsorption and desorption efficiencies.
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NANO
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2018
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IF 1.1
Shipeng Yang,Siwei Peng,Chunhui Zhang,Xuwen He,Yaqi Cai
Nanoparticles of the semiconductor catalyst Cd x Zn 1 − x S were embedded into the metal organic framework MIL-101(Cr) to obtain Cd x Zn 1 − x S@MIL-101(Cr) nanocomposites. These materials not only possess high surface areas and mesopores but also show good utilization of light energy. The ultraviolet-visible diffuse reflectance patterns of Cd x Zn 1 − x S@MIL-101(Cr) nanocomposites showed that Cd 0 . 8 Zn 0 . 2 S@MIL-101(Cr) possessed good visible light response ability among the synthesized nanocomposites. The photocatalytic performance of the Cd x Zn 1 − x S@MIL-101(Cr) nanocomposites were tested via degradation and mineralization of methylene blue in neutral water solution under light irradiation using a 300W xenon lamp. As a result, using Cd 0 . 8 Zn 0 . 2 S@MIL-101(Cr) as a catalyst, 99.2% of methylene blue was mineralized within 30 min. Due to the synergistic effect of adsorption by the MIL-101(Cr) component and photocatalytic degradation provided by the Cd 0 . 8 Zn 0 . 2 S component, the Cd 0 . 8 Zn 0 . 2 S@MIL-101(Cr) catalyst displayed superior photocatalytic performance relative to Cd 0 . 8 Zn 0 . 2 S and MIL-101(Cr). Furthermore, Cd 0 . 8 Zn 0 . 2 S@MIL-101(Cr) possessed excellent stability during photodegradation and exhibited good reusability. The remarkable photocatalytic performance of Cd 0 . 8 Zn 0 . 2 S@MIL-101(Cr) is likely due to the effective transfer of electrons and holes at the heterojunction interfaces.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2019
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IF 4.084
Guoru Li,Xiaobo He,Fengxiang Yin,Biaohua Chen,Huaqiang Yin
The development of highly efficient electrocatalysts with low cost for oxygen reduction reaction (ORR) is urgently required for metal-air batteries and fuel cells. In this work, Fe Co/MIL-101(Cr) with various molar ratios of Fe/Co as hybrid catalysts was prepared by a facile and mild impregnation method. MIL-101(Cr) increased the specific surface areas of the hybrid catalysts, thus improving the dispersion of Fe and Co species at their surfaces. The effects of Fe and Co species on ORR activity of the hybrid catalysts were investigated. It is found that the synergistic effects between the well-dispersed Fe and Co species contribute mainly to ORR activity. More specifically, Fe species exert a partial-charge-transfer-activation effect on Co ones, which reduces the charge transfer resistance and thus improves the catalytic activity . As a result, Fe Co/MIL-101(Cr) showed the excellent ORR activity, in which Co 50 Fe 50 /MIL-101(Cr) exhibited the superior ORR activity to the other prepared hybrid catalysts.
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ACS Sustainable Chemistry & Engineering
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2019
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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
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2018
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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
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2018
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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
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2018
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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
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2018
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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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JOURNAL OF POROUS MATERIALS
·
2019
·Vol. 26
·期 6
·1607-1618
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IF 1.947
Hou Pengchao,Xing Guangjian,Han Dan,Zhao Yan,Zhang Gang,Wang Hao,Zhao Chang,Yu Chunna
MIL-101(Cr)/graphene aerogel (MIL-101(Cr)/GA) was synthesized using a two-step synthesis and used as a high efficient adsorbent for wastewater purification. The as-prepared MIL-101(Cr)/GA was characterized using XRD, FTIR and Raman spectroscopy, XPS and FESEM to investigate its structure, composition and morphology. MIL-101(Cr)/GA exhibited a 3D interconnected macroporous framework comprised of graphene sheets, on which MIL-101(Cr) particles were dispersed uniformly. Dyes, organic solvents and oils were used to evaluate the adsorption performance of MIL-101(Cr)/GA, which exhibited an excellent adsorption capacity for both anionic methyl orange (331.5 mg g −1 ) and cationic rhodamine B (345.7 mg g −1 ) as well as 51–101 times its own weight of various solvents/oils. In addition, the MIL-101(Cr)/GA showed superior recycling stability for dyes and a rapid adsorption rate for solvents/oils. The excellent adsorption performance was attributed to a synergistic effect between MIL-101 and the graphene aerogel. The kinetic behavior for adsorption observed for MIL-101(Cr)/GA was well-fitted by a pseudo-second-order kinetic model. It is envisaged that MIL-101(Cr)/GA will be a promising adsorbent for the removal of pollutants and wastewater purification.
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