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layered double hydroxide

Maryam Rajabi, Somayeh Arghavani-Beydokhti, Behruz Barfi, Alireza Asghari
In the present work, a novel nanosorbent namely layered double hydroxides with 4-amino-5-hydroxyl-2,7-naphthalendisulfonic acid monosodium salt interlayer anion (Mg-Al-AHNDA-LDH) was synthesized and applied as a dissolvable nanosorbent in a centrifugeless ultrasound-enhanced air-agitated dispersive solid-phase extraction (USE-AA-D-SPE) method. This method was used for the separation and preconcentration of some metal ions including Cd(2+), Cr(6+), Pb(2+), Co(2+), and Ni(2+) prior to their determination using the micro-sampling flame atomic absorption spectrometry (MS-FAAS) technique...
March 8, 2017: Analytica Chimica Acta
Weijun Peng, Hongqiang Li, Shaoxian Song
CoAl-layered double hydroxide/fluorinated graphene (CoAl-LDH/FGN) composites were fabricated via a two-step hydrothermal method. The synthesized CoAl-LDH/FGN composites have been characterised by Powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), Transmission electron microscopy (TEM), Field-emission scanning electron microscopy (FESEM) and Energy dispersive X-ray spectroscopy (EDS), and Electrochemical measurements. The results indicated that the fluorinated carbon with various configuration forms were grafted onto the framework of graphene, and the C-F bond configuration and fluorine content could be tuned by the fluorination time...
January 18, 2017: ACS Applied Materials & Interfaces
Marko Pavlovic, Paul Rouster, Elodie Bourgeat-Lami, Vanessa Prevot, Istvan Szilagyi
Colloidal stability of polymeric latex particles was studied in the presence of oppositely charged layered double hydroxide (LDH) platelets of different interlayer anions. Adsorption of the LDH particles led to charge neutralization and to overcharging of the latex at appropriate concentrations. Mixing stable colloidal suspensions of individual particles results in rapid aggregation once the LDH adsorption neutralizes the negative charges of the polymer spheres, while stable suspensions were observed at high and low LDH doses...
January 12, 2017: Soft Matter
Neena Mitter, Elizabeth A Worrall, Karl E Robinson, Peng Li, Ritesh G Jain, Christelle Taochy, Stephen J Fletcher, Bernard J Carroll, G Q Max Lu, Zhi Ping Xu
Topical application of pathogen-specific double-stranded RNA (dsRNA) for virus resistance in plants represents an attractive alternative to transgenic RNA interference (RNAi). However, the instability of naked dsRNA sprayed on plants has been a major challenge towards its practical application. We demonstrate that dsRNA can be loaded on designer, non-toxic, degradable, layered double hydroxide (LDH) clay nanosheets. Once loaded on LDH, the dsRNA does not wash off, shows sustained release and can be detected on sprayed leaves even 30 days after application...
January 9, 2017: Nature Plants
Tuyen Nguyen, Michel Boudard, M João Carmezim, M Fátima Montemor
Consecutive layers of Ni(OH)2 and Co(OH)2 were electrodeposited on stainless steel current collectors for preparing charge storage electrodes of high specific capacity with potential application in hybrid supercapacitors. Different electrodes were prepared consisting on films of Ni(OH)2, Co(OH)2, Ni1/2Co1/2(OH)2 and layered films of Ni(OH)2 on Co(OH)2 and Co(OH)2 on Ni(OH)2 to highlight the advantages of the new architecture. The microscopy studies revealed the formation of nanosheets in the Co(OH)2 films and of particles agglomerates in the Ni(OH)2 films...
January 4, 2017: Scientific Reports
Sayantan Ray, Suman Saha, Biswanath Sa, Jui Chakraborty
Considering the existing drawbacks of methotrexate (MTX) with respect to its solubility and toxicity, we incorporated it in a nanoceramic matrix, Mg-Al-layered double hydroxide (LDH) to form LDH-MTX nanoparticles, and the same was in turn encapsulated in a nontoxic and biodegradable polymer, poly (D,L-lactide-co-glycolide) (PLGA), to arrest the initial burst release and dose-dumping-related toxicity, already reported by our group. Our present study was designed to evaluate the pharmacokinetics, tissue distribution, survival rate of the test animals, and antitumor efficacy of the PLGA-LDH-MTX nanoparticles and its counterpart without LDH, PLGA-MTX nanoparticles compared with bare MTX...
January 3, 2017: Drug Delivery and Translational Research
Anna S Uzhel, Alexandra V Zatirakha, Konstantin N Smirnov, Alexandr D Smolenkov, Oleg A Shpigun
Novel pellicular poly(styrene-divinylbenzene)-based (PS-DVB) anion exchangers with covalently-bonded hyperbranched functional ion-exchange layers containing negatively charged functionalities are obtained and examined. The hyperbranched coating is created on the surface of aminated PS-DVB substrate by repeating the modification cycles including alkylation with 1,4-butanediol diglycidyl ether (1,4-BDDGE), and amination of the terminal epoxide rings with methylamine (MA) or glycine (Gly). The influence of the position and the number of the layers with glycine, as well as of the total number of the layers of amine in the coating on the chromatographic properties of the obtained stationary phases is investigated...
December 22, 2016: Journal of Chromatography. A
Weijian Chen, Taotao Wang, Jiawei Xue, Shikuo Li, Zidan Wang, Song Sun
TiO2 -based photoanodes have attracted extensive attention worldwide for photoelectrochemical (PEC) water splitting, but these materials still suffer from poor electron-hole separation and low photoconversion efficiency. Here, the high PEC water splitting activity and long-term stability against photocorrosion of well-aligned hierarchical TiO2 @CoNi-layered double hydroxides nanotube arrays (TiO2 @CoNi-LDHs NTAs) are reported. The typical TiO2 @CoNi-LDHs NTAs exhibits enhancing photocurrent density of 4.4 mA cm(-2) at a potential of 1...
December 27, 2016: Small
Natalia Chubar, Vasyl Gerda, Dipanjan Banerjee
In this work, we report atomic-scale reconstruction processes in Fe-Ce oxide-based composites (hydrothermally precipitated at Fe-to-Ce dosage ratios of 1:0, 2:1, 1:1, 1:2, and 0:1), upon treatment at 300°C. The structural changes are correlated with the adsorptive removal of arsenate, phosphate, fluoride, bromide, and bromate. The presence of the carbonate-based Ce-component and surface sulfate in precursor samples creates favorable conditions for phase transformation, resulting in the formation of novel (unknown) layered compounds of Fe and Ce...
December 7, 2016: Journal of Colloid and Interface Science
Xiaofei Tan, Shaobo Liu, Yunguo Liu, Yanling Gu, Guangming Zeng, Xiaoxi Cai, ZhiLi Yan, Chunping Yang, Xinjiang Hu, Bo Chen
A biochar supported calcined-Mg/Al layered double hydroxides composite (CLDHs/BC) was synthesized by a one-pot slow pyrolysis of LDHs preloaded bagasse biomass. Multiple characterizations of the product illustrated that the calcined-Mg/Al layered double hydroxides (CLDHs) were successfully coated onto the biochar in slow pyrolysis of pre-treated biomass. The as-synthesized CLDHs/BC could efficiently remove antibiotic tetracycline from aqueous solutions. The coating of CLDHs significantly increased the adsorption ability of biochar, and CLDHs/BC exhibited more than 2 times higher adsorption capacity than that of the pristine biochar (BC) in the tested pH range...
December 21, 2016: Scientific Reports
Peng Fei Liu, Shuang Yang, Bo Zhang, Hua Gui Yang
Efficient and durable electrocatalysts from earth-abundant elements play a vital role in the key renewable energy technologies including overall water splitting and hydrogen fuel cells. Here, generally used CoFe based layered double hydroxides (LDHs) were first delaminated and exfoliated in the DMF-ethanol solvent (CoFe LDH-F), with enhancement both in oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The exfoliation process creates more coordinatively unsaturated metals and improves the intrinsic electronic conductivity, which is important in water electrolyzer reactions...
December 21, 2016: ACS Applied Materials & Interfaces
Zhiqiang Wang, Sha Zeng, Weihong Liu, Xingwang Wang, Qingwen Li, Zhigang Zhao, Fengxia Geng
Developing efficient but nonprecious bifunctional electrocatalysts for overall water splitting in basic media has been the subject of intensive research focus with the increasing demand for clean and regenerated energy. Herein, we report on the synthesis of a novel hierarchical hybrid electrode, NiFe-layered double hydroxide molecularly ultrathin sheets grown on NiCo2O4 nanowire arrays assembled from thin platelets with nickel foam as the scaffold support, in which the catalytic metal sites are more accessible and active and most importantly strong chemical coupling exists at the interface, enabling superior catalytic power toward both oxygen evolution reaction (OER) and additionally hydrogen evolution reaction (HER) in the same alkaline KOH electrolyte...
January 18, 2017: ACS Applied Materials & Interfaces
Vojislav R Stamenkovic, Dusan Strmcnik, Pietro P Lopes, Nenad M Markovic
Advances in electrocatalysis at solid-liquid interfaces are vital for driving the technological innovations that are needed to deliver reliable, affordable and environmentally friendly energy. Here, we highlight the key achievements in the development of new materials for efficient hydrogen and oxygen production in electrolysers and, in reverse, their use in fuel cells. A key issue addressed here is the degree to which the fundamental understanding of the synergy between covalent and non-covalent interactions can form the basis for any predictive ability in tailor-making real-world catalysts...
December 20, 2016: Nature Materials
Ana L Costa, Ana C Gomes, Martyn Pillinger, Isabel S Gonçalves, João Pina, João Sérgio Seixas de Melo
Steady-state and time-resolved absorption and fluorescence measurements are reported for Congo Red (CR) in aqueous and DMSO solutions. The very low fluorescence quantum yield (~10-4) for CR in dilute solutions together with the absence of a triplet state indicates that internal conversion is the dominant deactivation route with more than 99.99% of the quanta loss (attributed to the energy gap law). Although no direct evidence for trans-cis photoisomerization was obtained from absorption or fluorescence data, the global analysis of fs-transient absorption data indicates the presence of a photoproduct with a lifetime of ~170 ps that is suggested to be associated with such a process...
December 19, 2016: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Wojciech A Sławiński, Anja Olafsen Sjåstad, Helmer Fjellvåg
Layered double hydroxides (LDH) are a broad group of widely studied materials. The layered character of those materials and their high flexibility for accommodating different metals and anions make them technologically interesting. The general formula for the LDH compound is [M1-x(II)Mx(III)(OH)2][A(n-)]x/n·mH2O, where M(II) is a divalent metal cation which can be substituted by M(III) trivalent cation, and A(n-) is a charge compensating anion located between positively charged layers. In this paper we present a comprehensive study on possible structural disorder in LDH...
December 19, 2016: Inorganic Chemistry
Mostafa Hossein Beyki, Mosleh Mohammadirad, Farzaneh Shemirani, Ali Akbar Saboury
Polymeric ionomers with anion exchange capability are considered to be classes of environmentally friendly compounds as combination of them with anionic layered hydroxides constitute emerging advance materials. Biosorption by polymeric ionomer - layered double hydroxide (LDH) hybrid material exhibits an attractive green, low cost and low toxic - clean way. As a result, a novel anion exchange platform has been developed by the reaction of CaAl - LDH with Fe(2+), cellulose solution, epichlorohydrin and pyridine...
February 10, 2017: Carbohydrate Polymers
Juan Wu, Aipeng Deng, Wei Jiang, Renbing Tian, Yewen Shen
This study focuses on the synthesis and in vitro evaluation of magnetic nanocomposites (Fe3O4@LDH) as methotrexate (MTX) delivery system for targeted anticancer therapy. In which, the Fe3O4 nanoparticles acted as magnetically responsive carriers; the coating layer of layered double hydroxide (LDH) was used as a storehouse for MTX. The prepared Fe3O4@LDH nanocomposites exhibited a suitable size, good stability and magnetic responsibility (Ms 36.66emu/g); MTX successfully intercalated into the LDH of Fe3O4@LDH at an entrapment rate (%) of 91...
February 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
Anne-Marie Aucour, Jean-Philippe Bedell, Marine Queyron, Romain Tholé, Aline Lamboux, Géraldine Sarret
Wetlands play a key role in the immobilization of metallic contaminants. In this context the mechanisms of Zn sequestration and Zn transfer and storage in Typha latifolia L. colo-nizing a frequently flooded contaminated soil were studied. A combination of EXAFS spectroscopy, micro X-ray fluorescence (µXRF) and Zn isotope measurements was applied to soil, plant organs and decaying biomass. Zn was present in the soil as Zn-layered double hydroxide, as tetrahedral and octahedral sorbed Zn species, and as ZnS...
December 16, 2016: Environmental Science & Technology
Feng Peng, Hua Li, Donghui Wang, Peng Tian, Yaxin Tian, Guangyin Yuan, Demin Xu, Xuanyong Liu
Magnesium (Mg) and its alloys have been suggested as revolutionary biodegradable materials. However, fast degradation hinders its clinic application. To improve the corrosion resistance and biocompatibility of Mg-Nd-Zn-Zr alloy (JDBM), magnesium-aluminum-layered double hydroxide (Mg-Al LDH) was successfully introduced into Mg(OH)2 coating by hydrothermal treatment. The anions in the interlayer of Mg-Al LDH can be replaced by chloride ions, resulting in a relatively low chloride ion concentration near the surface of the coating...
December 28, 2016: ACS Applied Materials & Interfaces
Yanjing Zhu, Rongrong Zhu, Mei Wang, Bin Wu, Xiaolie He, Yechang Qian, Shilong Wang
Currently, nanoparticles have gained a great attention in the anti-tumor research area. However, to date, studies on the anti-metastasis action of core-shell SiO2@LDH (LDH: layered double hydroxide) nanoparticles remain untouched. Two emerging aspects considered are establishing research on the controlling delivery effect of SiO2@LDH combined with anti-cancer medicine from a new perspective. The fine properties synthetic SiO2@LDH-VP16 (VP16: etoposide) are practiced to exhibit the nanoparticle's suppression on migration and invasion of non-small cell lung cancer (NSCLC)...
November 2016: Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
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