CLAY MINERALS
·
2019
·Vol. 54
·期 3
·293-298
·
IF 1.787
Dong Li,Min Shen,Guofan Sun,Huiran Jin,Peng Cai,Zhihui Wang,Yeling Jin,Jing Chen,Shijie Ding
A Pickering emulsion was prepared via synergistic stabilization of a lipase and palygorskite particles. The optimum conditions for the stabilization of the Pickering emulsion, such as the concentrations of the palygorskite particles and lipase, were explored. The morphology of emulsion droplets was examined using digital optical microscopy and polarizing optical microscopy. The palygorskite–lipase co-stabilized Pickering emulsions were investigated by determination of the adsorption rate, pH and zeta potential of the aqueous dispersion, as well as by determining the contact angle values of the lipase solution on a palygorskite disc that was immersed in toluene. The catalytic performance of the immobilized lipase in the Pickering emulsion was studied via the investigation of its thermal stability, storage stability and reusability. The immobilized lipase showed greater stability than the free lipase. The lipase immobilized by Pickering emulsion retained a high level of activity even after seven periods of recycling.
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CELLULOSE
·
2019
·Vol. 26
·期 6
·4191-4204
·
IF 3.917
Cheng Deshan,Bai Xue,He Mantang,Wu Jihong,Yang Hongjun,Ran Jianhua,Cai Guangming,Wang Xin
Depositing anisotropic noble metal nanoparticles with high uniformity and yield on flexible substrates is the determining factor for surface enhanced Raman spectroscopy (SERS) detection. In this work, flexible, durable and sensitive SERS substrates were fabricated by in situ reduction of Ag nanoparticles on polydopamine templated cotton fabrics (CF) as catalytic hotspots to enhance the following deposition of Au nanoparticles. The coated CF were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy and X-ray diffraction to understand the surface morphology, chemical composition and crystalline structure, respectively. The SEM images indicate that the nanoparticles are dispersed evenly on the CF. 4-Mercaptobenzoic acid (4-MBA) has been used as the probe molecule to evaluate the sensitive and reproducible SERS properties of the as-fabricated SERS substrate. The as-prepared SERS substrates were demonstrated to detect carbaryl pesticides on a cucumber, and carbaryl with the concentration of as low as 10 −6 M (0.20 ppm) could be detected to ensure food safety.
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JOURNAL OF HAZARDOUS MATERIALS
·
2019
·
IF 7.65
Zhengwei Zhang,Kun Yan,Ling Zhang,Qian Wang,Ruixin Guo,Zhengyu Yan,Jianqiu Chen
Heavy metal cadmium (Cd) has drawn tremendous comcern due to its rigorous environmental and health hazards. Herein, we have presented an efficient and economical strategy for the removal and recycling of hazardous Cd ions using microalgae cells as the bioreactors. Remarkably, the green bio-platform for the bioproduction of CdSe nanoparticles (NPs) was developed depending on their orderly regulated and sustainable cellular environment. The biofabricated CdSe NPs manifested favorable photoluminescence properties, and presented well monodispersed spherical morphology and certain crystallinity structure with mean size of smaller than 7 nm. Especially, the fluorescence “turn off” sensing system based on the CdSe NPs was established to detect Hg 2+ . The nanosensor enables the quantitative analyses of Hg 2+ with a linear range of 0–2.0 μM and a detection limit of 0.021 μM. Furthermore, it was preliminarily speculated that the reducing biomolecules in the algae cells could be involved in the formation of CdSe NPs. This work not only provides new insights into the removal and recycling of hazardous Cd ions, but also brings a promising route for biosynthesis of CdSe NPs.
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PubMed
高影响因子
RSC Advances
·
2018
·Vol. 8
·期 29
·16088-16094
·
IF 2.936
Jianyun Yu,Chenhui Wang,Anming Wang,Ningning Li,Xinxin Chen,Xiaolin Pei,Pengfei Zhang,Stephen Gang Wu
To achieve dual-reuse of both enzyme and support in enzyme immobilization, hybrid nanoflowers (hNFs) were synthesized and crystallized in aqueous solution using calcium phosphate as inorganic component and enzyme as organic component. When hNFs lost their catalytic activity after reuse for times, they underwent dissolution and recrystallization to achieve the dual-cycle of enzyme and support. Six enzymes including papain, bromelain, trypsin, Lipase from Porcine Pancreas (PPL), Lipase from Thermomyces lanuginosus (TLL) and Lipase B from Candida antarctica (CALB) were chose as model enzymes and the obtained hNFs all presented high catalytic activity and thermal stability. The highest catalytic efficiency (Kcat/Km) of TLL-hNFs was 38.52 mM−1 s−1, 21.7 folds than that of free enzyme. Moreover, after heating for 6 h at 70 °C, the residual activities of TLL-hNFs, PPL-hNFs, and CALB-hNFs, were 78.3%, 72.9% and 84.3%, which were 4.57, 2.61 2.35 folds of that of their corresponding free one. Furthermore, the recovery rate of Ca3(PO4)2 were above 95% by recrystallizing the calcium phosphate with fresh enzymes after dissolving the used hNFs and removing the denatured enzyme. The recrystallized hNFs using the recovered phosphate salts and fresh enzymes all gave the consistent catalytic activities. This sustainable dual-cycle method depending on calcium phosphate crystallization, dissolution and recrystallization, was facile and efficient and can also be applied to other enzymes immobilization for industrial biocatalysis.
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CHINESE JOURNAL OF CATALYSIS
·
2019
·
IF 4.914
Jingqing Tian,Haocheng Li,Xin Zeng,Zichun Wang,Jun Huang,Chen Zhao
ABSTRACT Development of dry reforming of methane and carbon dioxide is an effective route to convert in-dustrial waste gases such as coke-oven gas and coal-to-oil gas into platform syngas. However, this process encounters severe problems of metal particle sintering and coke formation at high tem-peratures. In this work, we developed a new synthetic method for preparing confined Ni/MCM-41 catalysts, which impede the sintering of metal nanoparticles (NPs) and coke deposition at high temperatures, enabling them to be successfully applied to methane dry reforming . The method results in high activity and stability of the catalyst at 700 °C for 200 h. The Ni precursor is immersed in ethanol and impregnated into MCM-41 by the peculiar capillary action of hexagonal straight mesopores . By this method, 10 wt% Ni NPs (d = 2 nm) is equably confined to the mesoporous channels with strong metal-support interactions, as confirmed by HRTEM, TEM mapping, H2-TPR, and XRD measurements. Such a confined structure has a significant effect on the inhibition of metal NP agglomeration and carbon deposition during methane dry reforming, as evidenced by TEM, Raman, TGA, and TPO measurements of used Ni/MCM-41 catalysts. In contrast, unconfined Ni/MCM-41 catalysts, with Ni NPs located on the pore exteriors, are rapidly deactivated after 12 h due to the blocked contact between the active metal centers and the gas feedstock. Additionally, a fast increase in the Ni NP size and the formation of substantial carbon nanotubes on the unconfined catalyst surface are seen. This work offers a facile approach for the synthesis of anti-sintering, car-bon-resistant confined Ni catalysts that can operate at high temperatures
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CHEMICAL GEOLOGY
·
2019
·
IF 3.618
Jing Liu,Runliang Zhu,Qingze Chen,Huijun Zhou,Xiaoliang Liang,Lingya Ma,Steve C. Parker
Naturally occurring semiconducting metal (oxyhydr)oxides (MeO x ) are ubiquitous geosorbents and geocatalysts, regulating the geochemical behaviors of the chemicals in the environment. The interactions between these MeO x and redox-sensitive elements may involve both the photo-catalytic redox reactions and surface adsorption, and the interplay of the two processes, therefore, makes the interactions rather complex and may have unique environmental effects. The complex interactions between Cr (Cr(III) or Cr(VI)) and hematite under simulated sunlight irradiation were systematically studied under different geochemical conditions (pH, light irradiation, beginning Cr species, etc.). The batch experimentals, X-ray photoelectron spectroscopy (XPS), transmitted electron microscopy (TEM), and energy-dispersive spectroscopy (EDS) were used to determine the concentration and distribution of Cr species (Cr(III), Cr(VI), or the sum of the two) in the aqueous and solid phases. Here we found that both the oxidation of Cr(III) and the reduction of Cr(VI) were accelerated by hematite under sunlight irradiation, resulting in the enhanced immobilization of Cr on hematite. The reduction and oxidation efficiencies were pH-dependent and more evident under acidic condition. In the Cr (III) reaction systems, the reactions can be characterized by (1) the adsorption of aqueous Cr(III) (Cr(III) aq ) to hematite surfaces, (2) the oxidation of adsorbed Cr(III) (Cr(III) ad ) to Cr(VI) ad by the photogenerated holes on hematite, i.e., heterogeneous oxidation, (Bargar et al., 1997) the accumulation of Cr(III) ad on hematite enhanced by Cr(VI) ad , and even the formation of Cr-riched precipitation, which was observed by TEM , and (3) the homogeneous oxidation of Cr(III) aq to Cr(VI) aq by the hydroxyl radicals , generating through interaction between O 2 and the photogenerated electrons (more evident under acidic environment, e.g., pH 3). In the Cr(VI) reaction systems, the reduction of Cr(VI) ad by photogenerated electrons from hematite was also noticeable, with the yielded Cr(III) being fixed on the surfaces. Although the reactions in reduction systems were less extensive than those in the oxidation systems, the reduction reactions would reduce the environmental toxicity of Cr species; while in the oxidation systems, inspite of the higher removal efficiency, the oxidation processes actually increased the environmental risk of Cr. Our results clearly show that hematite could either oxidize Cr(III) or reduce Cr(VI), influencing the speciation and immobilization of Cr under sunlight irradiation. In this term, the natural semiconducting MeO x (e.g., hematite) on Earth's surfaces should play a significant role in affecting the environmental behaviors and toxicities of the redox-sensitive elements (e.g., Cr) through adsorption and photo-catalytic redox processes.
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Nanomaterials and Nanotechnology
·
2015
·
IF 0.857
Tingting Yang,Mingliang Du,Ming Zhang,Han Zhu,Pan Wang,Meiling Zou
A simple and effective method for the preparation of platinum nanoparticles (Pt NPs) grown on amino-functionalized halloysite nanotubes (HNTs) was developed. The nanostructures were synthesized through the functionalization of the HNTs, followed by an in situ approach to generate Pt NPs with diameter of approximately 1.5 nm within the entire HNTs. The synthesis process, composition and morphology of the nanostructures were characterized. The results suggest PtNPs/NH2-HNTs nanostructures with ultrafine PtNPs were successfully synthesized by green chemically-reducing H2PtCl6 without the use of surfactant. The nanostructures exhibit promising catalytic properties for reducing potassium hexacyanoferrate(III) to potassium hexacyanoferrate(II). The presented experiment for novel PtNPs/NH2-HNTs nanostructures is quite simple and environmentally benign, permitting it as a potential application in the future field of catalysts.
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JOURNAL OF ELECTROANALYTICAL CHEMISTRY
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2014
·
IF 2.871
Jiapeng Fu,Dawei Li,Guohui Li,Fenglin Huang,Qufu Wei
We report a facile approach to synthesize and immobilize silver nanoparticles (AgNPs) onto carboxymethyl cellulose (CMC)-modified electrospun cellulose nanofibers and demonstrate the potential application of as-prepared AgNPs-CMC/cellulose composite nanofibrous mats as effective biosensor substrate materials. Cellulose nanofibers were prepared by the combination of electrospinning with deacetylation. Then, CMC was adsorbed onto cellulose nanofibers to complex silver ions through the chemical binding with the free carboxyl groups of CMC for subsequent reductive formation of AgNPs . The AgNPs-CMC/cellulose nanofibers immobilized with laccase (Lac) by electrostatic interactions were used as biosensor substrate materials for catechol detection. The cyclic voltammetries revealed that the AgNPs-CMC/cellulose nanofibers was beneficial to the immobilization of Lac and facilitated the direct electron transfer between Lac and electrode. Lac/AgNPs-CMC/cellulose/glassy carbon electrode exhibited a detection limit of 1.64 μM (S/N = 3), and a wide linear range from 4.98 μM to 3.65 mM, as well as good repeatability, reproducibility, stability, and selectivity. The CMC/cellulose nanofibrous mats have great potential applications as substrate materials for different biosensors by immobilizing other different functional nanoparticles or enzyme on them.
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JOURNAL OF APPLIED POLYMER SCIENCE
·
2013
·Vol. 131
·期 3
·
IF 1.395
Ting Li,Yuan Ren,Chaohai Wei
Polyvinyl alcohol(PVA) bead crosslinked with boric acid has been widely utilized as a microorganism immobilization carrier. However, it has some disadvantages such as drastic cell viability loss, small adsorption capacity and mass transfer limitation. To improve upon these drawbacks, a new method to prepare PVA composite pieces with the addition of activated carbon (AC) and poly-3-hydroxybutyrate(PHB) was explored through a combination of freezing/thawing and the boric acid method and by using Tween-80 to improve the mass transfer performance of hydrophobic organics. m -Cresol and pyrene were used as representative compounds with benzene ring structures to model hydrophilic and hydrophobic organics in order to test the performance of PVA pieces. The results showed that, compared with the boric acid method alone, a combination of freezing/thawing and the boric acid method led to a decrease in total organic carbon(TOC) loss from 0.315 g g −1 to 0.033 g g −1 and increased the oxygen uptake rate(OUR) of microorganisms from 0.03 mg L −1 ·min −1 to 0.22 mg L −1 min −1 . The m -cresol equilibrium adsorption amount of the PVA-SA(sodium alginate)-PHB-AC piece was 2.80 times that of the PVA-SA piece. The diffusion coefficient of pyrene in the PVA-SA-PHB-AC piece increased from 0.53×10 −9 m 2 min −1 to 2.30×10 −9 m 2 min −1 with increasing concentrations of Tween-80 from 1000 mg L −1 to 5000 mg L −1 . The PVA-SA-PHB-AC composite carrier demonstrated great scope for immobilizing microorganisms for practical wastewater bio-treatment. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131 , 39837.
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ANALYTICA CHIMICA ACTA
·
2013
·
IF 4.387
Qingxiang Wang,Yingtao Ding,Feng Gao,Shulian Jiang,Bin Zhang,Jiancong Ni,Fei Gao
A novel DNA biosensor was fabricated through a facile sulfamide coupling reaction. First, the versatile sulfonic dye molecule of 1-amino-2-naphthol-4-sulfonate (AN-SO 3 − ) was electrodeposited on the surface of a glassy carbon electrode (GCE) to form a steady and ordered AN-SO 3 − layer. Then the amino-terminated capture probe was covalently grafted to the surface of SO 3 − -AN deposited GCE through the sulfamide coupling reaction between the amino groups in the probe DNA and the sulfonic groups in the AN-SO 3 − . The step-by-step modification process was characterized by electrochemistry and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. Using Ru(NH 3 ) 6 3+ as probe, the probe density and the hybridization efficiency of the biosensor were determined to be 3.18 × 10 13 strands cm −2 and 86.5%, respectively. The hybridization performance of the biosensor was examined by differential pulse voltammetry using Co(phen) 3 3+/2+ (phen = 1,10-phenanthroline) as the indicator. The selectivity experiments showed that the biosensor presented distinguishable response after hybridization with the three-base mismatched, non-complementary and complementary sequences. Under the optimal conditions, the oxidation peak currents of Co(phen) 3 3+/2+ increased linearly with the logarithm values of the concentration of the complementary sequences in the range from 1.0 × 10 −13 M to 1.0 × 10 −8 M with a regression coefficient of 0.9961. The detection limit was estimated to be 7.2 × 10 −14 M based on 3 σ .
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ELECTROCHIMICA ACTA
·
2015
·
IF 4.504
Tingting Yang,Mingliang Du,Han Zhu,Ming Zhang,Meiling Zou
A facile strategy for the preparation of novel Pt nanoparticles/carbon nanofibers (PtNPs/CNFs) nanostructure by combining the electrospinning and carbonization process is demonstrated. PtNPs were obtained in polyacrylonitrile nanofibers (PANFs) through an in situ reduction as well as electrospinning, and then the PtNPs/PANFs nanostructure was converted to PtNPs/CNFs following a carbonization process. The formation and structure of the synthesized PtNPs/CNFs nanostructure were systematically characterized, suggesting that PtNPs with diameter of ca. 8.8 nm were evenly dispersed in CNFs and nearly no aggregation was observed. The results indicate that the nanostructure possesses high catalytic activity for both hydrogen evolution reaction (HER) and electrochemical sensor, as well as long-term stability for HER, serving as a bifunctional catalyst. The present investigations provide a general route for the fabrication of novel electrocatalyst, which may also be extended to synthesize other metal nanoparticles/CNFs nanostructures.
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ACS Sustainable Chemistry & Engineering
·
2015
·
IF 4.642
Yuchao Wang,Da Shi,Shengyang Tao,Wentong Song,Hongmin Wang,Xinkui Wang,Guangtao Li,Jieshan Qiu,Min Ji
A general, green chemistry approach is developed for the immobilization of inorganic catalysts in monolithic porous flow-reactors for continuous flow reactions, in which pyrogallol (PG) acts as an assistant layer for the in situ immobilization of various catalysts on the inner pore surface of the flow-reactor. Au nanoparticles (AuNPs), Al2O3, and phosphotungstic acid (HPW) are selected as examples of noble metals, metal oxides, and polyoxometalate (POM) type catalysts, respectively, and the corresponding flow-reactors show high catalytic performance in continuous flow hydrogenation reactions, esterification reactions, and Knoevenagel reactions, respectively. These reactions are important in the treatment of environmental contaminants and in the chemical industry. In addition, multiple monolithic flow-reactors can be assembled together for efficient performance of multi-step cascade reactions.
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危险品化学品经营许可证（带存储）