INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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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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NANO
·
2018
·
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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RSC Advances
·
2018
·Vol. 8
·期 71
·41003-41011
·
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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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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FIBERS AND POLYMERS
·
2014
·Vol. 15
·期 7
·1364-1368
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IF 1.113
Chen Zaina,Feng Xiaoxiao,Han Danmin,Wang Liting,Cao Weipen,Shao Linjun
Porous polyacrylonitrile (PAN) fiber mat was prepared by electrospinning PAN in N,N -dimethylformide solution with poly(methyl methacrylate) (PMMA) as pore-forming agent. Then, the porous PAN fiber mat was chemical modified by the tetraethylenepentamine to acquire aminated porous polyacrylonitrile (APPAN) fiber mat. Common aminated PAN fiber mat was also prepared for comparison. The surface morphologies of the APPAN and PAN fiber mat were characterized by scanning electron microscopy (SEM) and the corresponding specific surface areas were also measured. FT-IR/ATR spectra of the APPAN and PAN fiber mat were recorded for analysis of the surface chemical structures. The Cr(VI) absorption results demonstrated that the porous structure in the fiber could obviously increase the absorption capacity of the fiber mat.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2015
·
IF 2.999
Qian Qi,Yan Liu,Hui Zhang,Yinsheng Li,Hanqin Liang,Zhengren Huang
SiC p /Hastelloy composites were fabricated by pressureless Ti-activated infiltration process. The wetting and infiltration behaviors of Hastelloy on the SiC substrates and the interfacial reaction between the SiC particles and Hastelloy were investigated by real-time observation system, X-ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with energy X-ray dispersive spectroscopy (EDS) system. The results demonstrated that the Hastelloy had a good wettability on SiC ceramic and could spontaneously infiltrate into the Ti-activated SiC preform. Moreover, intensive interfacial reaction similar to SiC/Ni system was found between the SiC particles and Hastelloy, which induced defects in the microstructure. In order to inhibit the interfacial reaction, Al 2 O 3 coating on SiC particles was adopted as a diffusion barrier, which effectively reduced the extent of the interfacial reactions.
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LANGMUIR
·
2017
·
IF 3.833
Dongfang Wang,Guilong Zhang,Linglin Zhou,Min Wang,Dongqing Cai,Zhengyan Wu
A novel magnetic nanocomposite was synthesized using graphene oxide (GO), polyethylenimine (PEI), and Fe3O4 to removal hexavalent chromium (Cr(VI)) from water and soil. Therein, GO was functionalized with plenty of −NH2 by the modification of PEI through an amidation reaction, and the resulting GO/PEI reacted with FeSO4·7H2O and NaBH4 to obtain RGO/PEI/Fe3O4 (the optimal one is designated as ORPF) through an oxidation–reduction reaction. ORPF could effectively adsorb Cr(VI) through electrostatic attraction, and the adsorbed Cr(VI) ions were partially reduced to trivalent chromium (Cr(III)) with low toxicity by RGO (π electron). Afterward, the resulting ORPF-Cr could be conveniently removed from water with a magnet, achieving the maximum Cr(VI) removal capacity of 266.6 mg/g. Importantly, ORPF, once carried by sponge particles, could efficiently remove Cr(VI) from soil, and the resulting mixture could be facilely collected with a magnet on a filter net. Besides, the leaching experiment suggested that, when supported by filter paper, ORPF was able to decrease the number of leached Cr(VI) ions and meanwhile reduce them to Cr(III). This work provides a promising approach to remediate Cr(VI)-contaminated water and soil using a nanocomposite, which has a huge number of application prospects.
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Scientific Reports
·
2017
·Vol. 7
·期 1
·1-11
·
IF 4.259
Laipan Minwang,Fu Haoyang,Zhu Runliang,Sun Luyi,Zhu Jianxi,He Hongping
Recycling solid waste as functional materials is important for both environmental remediation and resource recycling. This study attempts to recycle spent Cu/Fe layered double hydroxide (Cu/Fe-LDH) which is generated from the adsorption of dyes by converting to Cr(VI) reductant and porous carbon material. Results showed that the obtained reductant was mainly composed of Fe 0 and Cu 0 , and exhibited good reductive activity toward Cr(VI). The species of Fe 0 , Fe 2+ , Cu 0 , and Cu + all favored the reduction of Cr(VI) according to X-ray photoelectron spectroscopy analysis. During Cr(VI) removal, solution pH could increase to neutral which caused the metal ions to precipitate near completion. On the other hand, the spent Cu/Fe-LDH could be employed to produce porous carbon materials, and the generated waste metals solution herein could be reused for LDH synthesis. Specific surface areas of the obtained carbon materials varied from 141.3–744.2 m 2 /g with changes in adsorbed amount of dyes on the LDH. This study illustrates that all the components of wastes can be useful resources, offering a simple recycling approach for similar organic-inorganic solid wastes. This work also enlightens us that designing a proper initial product is crucial to make waste recycling simpler.
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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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Analytical Methods
·
2016
·Vol. 8
·期 28
·5684-5689
·
IF 1.915
Na Xu,Quan Zhu,Xiang-Yue Kong,Lei Meng
Polyethyleneimine protected silver nanoclusters (AgNCs@PEI) were prepared and used as high sensitive fluorescence probes for detecting Cr(VI). The mechanism worked by combining Cr(VI) with a primary amine of AgNCs@PEI causing electrostatic interaction, which led to the aggregation of AgNCs, as well as fluorescence quenching. Compared with other fluorescence sensors of Cr(VI) detection, this probe shows excellent performances: (i) The fluorescence probe responds immediately after adding Cr(VI). (ii) The fluorescence quenching efficiency of AgNCs@PEI was linearly related to the concentration of Cr(VI) over the range from 0.5 nM to 25 μM. (iii) The limit of detection is as low as 0.05 nM. (iv) High selectivity for Cr(VI) in 14 types of normal metal ions were obtained and especially the probe can be applied in both acidic and alkaline conditions (pH 2.0–11.0). (v) The probe can be used for the determination of Cr(VI) in real samples with satisfactory results. Therefore, the fluorescence probe is of practical significance and application prospects.
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RSC Advances
·
2016
·Vol. 6
·期 64
·59292-59298
·
IF 3.289
Jianqiao Zhang,Huan Chen,Zi Chen,Jiaojie He,Wenxin Shi,Dongmei Liu,Huizhong Chi,Fuyi Cui,Wei Wang
A high-performance, cost-effective and spongeous adsorbent was rationally designed for Cr(VI) removal from aqueous solution based on PPy modified natural quasi two-dimensional (2D) structures. Core of corncobs, a kind of agricultural waste composed of quasi 2D sub-micro sheets, has a unique macroporous spongeous microstructure. In consideration of the unique chemical structure of polypyrrole (PPy) and microstructure of the natural sponge, we constructed the microstructured spongeous adsorbents. The PPy active layer provided reactive sizes to detoxifies Cr(VI) ions by ion-exchange. While the spongeous microstructure provided by the microsheets could enhance the adsorption performance by increasing active areas and facilitating the access of pollutants inside the adsorbents. Compared with artificial nano-powder adsorbents, CC–PPy displayed larger advantage in separation process and fabrication/operation cost. Compared with other bulk-style PPy composites, the adsorption capacity of CC–PPy was several times higher. In addition, the regeneration and stability of CC–PPy was outstanding with no loss in the adsorption to Cr(VI) even after 3 adsorption–desorption cycles. The present development provides a solution to design highly efficient and cost-effective water treatment agents.
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RSC Advances
·
2016
·Vol. 6
·期 93
·90232-90238
·
IF 3.289
Xiao-Fang Liu,Hu Li,Heng Zhang,Hu Pan,Shan Huang,Kai-Li Yang,Song Yang
Catalytic ethanolysis of furfuryl alcohol (FA) to ethyl levulinate (EL) with MIL-101(Cr)–SO3H, prepared by simple one-pot hydrothermal treatment, is presented for the first time. The as-prepared catalyst with high surface area, hydrothermal and chemical stability, good dispersion, and feasible accessibility of –SO3H Brønsted acid sites was found to show superior performance to other sulfonic acid-functionalized solid catalysts. Besides the special textural properties, the obtained good catalytic activity of 79.2% EL yield and 100% FA conversion were also dependent on the density and strength of the Brønsted acid and the reaction parameters. A slight loss of catalytic activity after five consecutive recycles and the hot filtration experiment confirmed the good stability of MIL-101(Cr)–SO3H. Two coexisting reaction paths for the ethanolysis of FA to EL catalyzed by MIL-101(Cr)–SO3H were proposed, wherein 2-ethoxymethylfuran (2-EMF) was observed to be the dominant intermediate.
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