From old to new inorganic materials for advanced applications: The paradigmatic example of the sepiolite clay mineral

This review article focuses on sepiolite fibrous clay mineral, which has been selected here as an example of an ancient inorganic natural material that is currently receiving much attention as excellent candidate for advanced materials and applications. Sepiolite clay is an abundant hydrated magnesium silicate whose crystal structure determines the presence of nanoporous cavities as well as large surface and rheological properties of great interest for the further design of functional materials. The present work introduces and discusses the relationship between aspects of this clay, in terms of its structural and morphological organization, and its physicochemical characteristics from which emerging applications arise. One of the sections is devoted to describe current industrial applications of commercially available sepiolite-based materials. As sepiolite can be considered a nanomaterial by itself, approaches including its controlled chemical and physical modifications intended to develop new advanced inorganic and hybrid nanostructured materials provided with pre-designed functionalities. Among them, polymer nanocomposites that include bionanocomposites and carbon-sepiolite nanomaterials, materials for adsorption of pollutants, functionalization with magnetic nanoparticles, active phase of sensors and DNA support for gene transfer are some of the examples that we refer to in the present review articleThis research was partially funded by AEI (Spain), FEDER (EU), the European Union’s Horizon research and innovation program under the Marie Skłodowska-Curie Action, which grant numbers are MAT2015- 71117-R, PID2019-105479RB-I00 and GA 101064359, respectivel

Multicomponent bionanocomposites based on clay nanoarchitectures for electrochemical devices

Based on the unique ability of defibrillated sepiolite (SEP) to form stable and homogeneous colloidal dispersions of diverse types of nanoparticles in aqueous media under ultrasonication, multicomponent conductive nanoarchitectured materials integrating halloysite nanotubes (HNTs), graphene nanoplatelets (GNPs) and chitosan (CHI) have been developed. The resulting nanohybrid suspensions could be easily formed into films or foams, where each individual component plays a critical role in the biocomposite: HNTs act as nanocontainers for bioactive species, GNPs provide electrical conductivity (enhanced by doping with MWCNTs) and, the CHI polymer matrix introduces mechanical and membrane properties that are of key significance for the development of electrochemical devices. The resulting characteristics allow for a possible application of these active elements as integrated multicomponent materials for advanced electrochemical devices such as biosensors and enzymatic biofuel cells. This strategy can be regarded as an "a la carte" menu, where the selection of the nanocomponents exhibiting different properties will determine a functional set of predetermined utility with SEP maintaining stable colloidal dispersions of different nanoparticles and polymers in water

Espumas rígidas de tipo composite basadas en biopolímeros combinados con arcillas fibrosas y su método de preparación

Espumas rígidas de tipo composite basadas en biopolímeros combinados con arcillas fibrosas y su método de preparación. La presente invención se refiere a espumas rígidas de tipo composite que comprenden una matriz biopolimérica y partículas de silicatos pertenecientes a la familia de las arcillas fibrosas (sepiolita y palygorskita). La invención también se refiere al procedimiento de preparación de estos materiales, en el que la etapa de secado mediante liofilización o secado supercrítico es fundamental para obtener materiales de alta porosidad, así como a su uso en aplicaciones diversas tales como aislamiento acústico y térmico, material de embalaje, soporte de sólidos con propiedades eléctricas, magnéticas y ópticas, así como de fármacos y especies biológicas.Peer reviewedConsejo Superior de Investigaciones Científicas (España

Nanoarchitectures Based on Layered Titanosilicates Supported on Glass Fibers: Application to Hydrogen Storage

This work reports on the synthesis of nanosheets of layered titanosilicate JDF-L1 supported on commercial E-type glass fibers with the aim of developing novel nanoarchitectures useful as robust and easy to handle hydrogen adsorbents. The preparation of those materials is carried out by hydrothermal reaction from the corresponding gel precursor in the presence of the glass support. Because of the basic character of the synthesis media, silica from the silicate-based glass fibers can be involved in the reaction, cementing its associated titanosilicate and giving rise to strong linkages on the support with the result of very stable heterostructures. The nanoarchitectures built up by this approach promote the growth and disposition of the titanosilicate nanosheets as a house-of-cards radially distributed around the fiber axis. Such an open arrangement represents suitable geometry for potential uses in adsorption and catalytic applications where the active surface has to be available. The content of the titanosilicate crystalline phase in the system represents about 12 wt %, and this percentage of the adsorbent fraction can achieve, at 298 K and 20 MPa, 0.14 wt % hydrogen adsorption with respect to the total mass of the system. Following postsynthesis treatments, small amounts of Pd (<0.1 wt %) have been incorporated into the resulting nanoarchitectures in order to improve their hydrogen adsorption capacity. In this way, Pd-layered titanosilicate supported on glass fibers has been tested as a hydrogen adsorbent at diverse pressures and temperatures, giving rise to values around 0.46 wt % at 298 K and 20 MPa. A mechanism of hydrogen spillover involving the titanosilicate framework and the Pd nanoparticules has been proposed to explain the high increase in the hydrogen uptake capacity after the incorporation of Pd into the nanoarchitecture.We thank the CICYT (Spain, projects MAT2009-09960 and MAT2012-31759), Obra Social la Caixa, Aragon Government (GA-LC-019/2011), ESF, Generalitat Valenciana, and FEDER (PROMETEO/2009/047) for financial support. J.P.-C. is grateful for a Ph.D. grant (FPI, BES-2010-038410) from the Spanish Ministerio de Ciencia e Innovación

Functional biohybrid materials based on halloysite, sepiolite and cellulose nanofibers for health applications

Multicomponent nanopaper from the assembly of nanotubular halloysite, microfibrous sepiolite and cellulose nanofibers was developed for diverse functional applications such as slow release of antibacterial model drugs loaded into halloysite lumen

Downstream processing of high chain length polysialic acid using membrane adsorbers and clay minerals for application in tissue engineering

Polysialic acid (polySia) is a carbohydrate polymer of varying chain length. It is a promising scaffold material for tissue engineering. In this work, high chain length polySia was produced by an Escherichia coli K1 strain in a 10-L bioreactor in batch and fed-batch mode, respectively. A new downstream process for polySia is presented, based on membrane adsorber technology and use of inorganic anion exchanger. These methods enable the replacement of precipitation steps, such as acetone, cetavlon, and ethanol precipitation of the already established purification process. The purification process was simplified, while process efficiency and product qualities were improved. The overall yield of polySia from a 10-L batch cultivation process was 61% and for 10-L fed-batch cultivation process the yield was 40% with an overall purity of 98%. The endotoxin content was determined to be negligible (14 EU mg-1). The main advantage of this new downstream process is that polySia with high chain length of more than 130 degree of polymerization can be obtained. In fed-batch cultivation, chain lengths up to 160 degree of polymerization were obtained.DFG/FOR/54

Magnetic and electronic properties of bimagnetic materials comprising cobalt particles within hollow silica decorated with magnetite nanoparticles

Bimagnetic materials were fabricated by decorating the external surface of rattle-type hollow silica microspheres (which themselves contain metallic cobalt nanoparticles) with magnetite nanoparticles; thus, each magnetic substance was spatially isolated by the silica shell. The amount of magnetite decoration on the co-occluded hollow silica was varied from 1 to 17 mass %. Magnetic and electronic properties of the resulting bimagnetic materials were characterized by superconducting quantum interference device measurements and X-ray absorption spectroscopy, respectively. The ferrous iron in the bimagnetic sample was slightly more oxidized than in the magnetite reference, probably from some charge-transfer because of the SiO2 surface contact, although the overall oxidation state of the samples is very similar to that of magnetite. The temperature dependence of the sample magnetization recorded with Zero Field Cooling and Field Cooling resulted in blocking temperatures for the bimagnetic materials that were close to that of magnetite nanoparticles (176K) and were lower than that for the bare Co-occluded hollow silica (which was above room temperature). Values of coercive force and exchange bias at 300K became quite small after decoration with only minimal amounts of magnetite nanoparticles (1-3 mass %) and were lower than those of magnetite. This is the first example of enhancing superparamagnetism by spatial separation of both Co and magnetite magnetic nanoparticles using a thin wall of diamagnetic silica.ArticleJOURNAL OF APPLIED PHYSICS. 114(12):124304 (2013)journal articl

Chitosan-smectite biointerfaces vs. Alkylammonium-clay interfaces in adsorption process

Two series of chitosan-clay nanocomposites were synthesized using commercial (CLOISITE® Na+ ) and Na+ -enriched Serbian clay from seldom investigated locality Mečji Do. The samples were characterized by X-ray diffraction and intercalation of chitosan into bilayer structures was confirmed for particular chitosan/clay ratio in both series of chitosan-clay naonocomposites. Reactivity of chitosan-smectite biointerfaces vs. alkylammonium-clay interfaces in adsorption process was compared using textile dye Reactive Black 5 (RB5) as adsorbate. Chitosan-clay naonocomposites had similar adsorption uptake, being more than three times higher than adsorption uptake of commercial alkylammonium-clay CLOISITE® 30B.The Langmuir adsorption model was found to be appropriate for all investigated adsorbents