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This work was financially supported by MICINN (PID2019-106832RB-I00), MICINN through the Severo Ochoa Program for Centers of Excellence for the FUNFUTURE (CEX2019-000917-S project) and the Generalitat de Catalunya (2017/SGR/1720). D. Ch.-L. acknowledges funding by project no. PGC2018-102047-B-I00 (MCIU/AEI/FEDER, UE). Zhen Li is enrolled in the UAB PhD program and acknowledges the China Scholarship Council (CSC) for his PhD grant (201808310071)., A new unsymmetric carborane-based dicarboxylic linker provided a 1D Cu2-paddle wheel coordination polymer (2) with much higher hydrolytic stability than the corresponding 2D Cu2-paddle wheel polymer (1), obtained from a related more symmetrical carborane-based linker. Both 1 and 2 were used as efficient heterogeneous catalysts for a model aza-Michael reaction but only 2 can be reused several times without significant degradation in catalytic activity., Spanish Government, European Commission PID2019-106832RB-I00, MICINN through the Severo Ochoa Program for Centers of Excellence for the FUNFUTURE CEX2019-000917-S, Generalitat de Catalunya, General Electric 2017/SGR/1720, MCIU/AEI/FEDER, UE PGC2018-102047-B-I00, China Scholarship Council 201808310071

The reaction between 2,4,6-tris(4-pyridyl)-1,3,5-triazine (4-tpt) and copper(II) hexafluoroacetylacetone (Cu(hfa)2) yields two different 1D metal–organic frameworks (MOFs), [(Cu(hfa)2)2(4-tpt)]n (1) and [Cu(hfa)2(4-tpt)]n (2). The Cu:4-tpt ratio in the new MOFs is determined by the reaction medium, particularly, the solvent used. The two compounds have been fully characterized, including crystal structure elucidation. [(Cu(hfa)2)2(4-tpt)]n (1), with a 2:1 Cu:4-tpt ratio, could be precipitated in either 1,1,2-trichloroethane or supercritical CO2. In (1), 4-tpt shows a tritopic coordination mode, but only half of the Cu(hfa)2 subunits act as a node, thus connecting two 4-tpt and giving a 1D network. The other half of Cu(hfa)2 subunits are connected only to one pyridine and thus protrude along the chains. The later Cu(hfa)2 fragments show a labile character and can be dissolved in diethyl ether to give the second MOF [Cu(hfa)2(4-tpt)]n (2), with a 1:1 Cu:4-tpt ratio. The compound (2) has also a 1D structure, with all the incorporated copper atoms acting as nodes. In this case, the packing of the chains defines accessible channels, which are perpendicular to the chain axis. After activation, N2 adsorption/desorption measurements at 77 K confirm the microporous character of (2) with an apparent surface area of 190 m2 g−1. Besides, at 273 K this material clearly shows a significant adsorption of CO2 prompted by noncoordinated nitrogen in the triazine linker., This work was supported by the Spanish Ministry of Science and Innovation (MICINN) through the Severo Ochoa Program for Centers of Excellence (CEX2019-000917-S) and the Spanish National Plan of Research with project PID2020-115631GB-I00. The measures for the elucidation of the crystal structures were performed at MSPD and XALOC beamlines at ALBA Synchrotron with the collaboration of ALBA staff., With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).

Post-synthetic modification of a dynamic carborane-based soft porous crystal (1 * DMF) by in situ polymerization of pyrrole to polypyrrole (PPy) provided a permanently porous MOF/polypyrrole hybrid composite material that did not show the dynamic behavior of the mother MOF. Apart from stability, the introduction of conductive PPy in the composite material brings new properties to the otherwise non-conductive MOF., This work was financially supported by MINECO (CTQ2016-75150-R, PID2019-106832RB-I00) and the Generalitat de Catalunya (2017/SGR/1720). ICMAB acknowledges the support of the Spanish MINECO (Grant SEV-2015-0496). Z. Li is enrolled in the UAB PhD program and acknowledges the China Scholarship Council (CSC) for his PhD grants (201808310071). Z. Li thanks Fangchang Tan and Lei Gan for their assistance with the synthesis of 1 ⊃ DMF. The present publication is dedicated to Prof. Alan Welch on the occasion of his retirement from Heriot-Watt University.

Soft crystallization routes for the controlled growth of oneand two-dimensional Cu(II)-coordination polymers of the type [(Cu- (hfa)2)x(3-tpt)]n (hfa = hexafluoroacetylacetonate, 3-tpt = 2,4,6-tris(3- pyridyl)-1,3,5-triazine) are described. Three volatile solvents with different protic/aprotic characteristics were chosen as the reaction media, e.g., supercritical CO2, chloroform, and ethanol. Five (1−5) new compounds were crystallized, with different structures and Cu(II)/3-tpt ratios. The structures of 3-tpt and five new coordination polymers were elucidated by single-crystal synchrotron X-ray diffraction. A description of the crystallization pathways followed for the synthesis of the individual compounds is given based on the protic or aprotic character of the used solvents and reagents’ solubility constraints. The main novelty of the work relies in establishing the foundations of 3-tpt isomeric control during crystallization through solvent selection. From the five precipitated new compounds, 3 displays a significant framework flexibility, associated with N2 adsorption at low temperature, presenting a stepwise adsorption isotherm. The N2 adsorption process was followed by in situ synchrotron X-ray powder diffraction, This work was financed by the Spanish National Plan of Research with project CTQ2017-83632. C.D., J.G.P., A.B., N.P.-G., J.F., and A.M.L.-P. acknowledge the financial support from the Spanish MEC, through the Severo Ochoa Program for Centres of Excellence in R&D (SEV-2015-0496). This work (N.P.-G., A.B., and J.F.) has been done in the framework of the doctoral program “Chemistry” of the Universitat Autonoma de Barcelona. A.M.L.-P. acknowledges the RyC- ̀ 2012-11588 contract. N.P.-G. and A.B. acknowledge FPI grants. ALBA synchrotron is acknowledged for the provision of beam time.

Extraordinary properties are often described for 2D nanocomposites involving graphene flakes and a second component selected from particles or fibers. From this family of hybrid materials, this study is centered on composites based on graphene oxide (GO), a multifunctional oxygenated version of graphene, and superparamagnetic iron oxide nanoparticles (SPIONs), with applications as contrast agents in magnetic resonance imaging (MRI). The research focuses on the loading of SPIONs onto a GO surface via a simple one-pot supercritical CO2 technique. The developed all-green synthesis approach allows the preparation of hybrid materials shaped into aerogels with large mesoporosity. The use of coated and uncoated components in the aerogel composites is analyzed with emphasis in the significance of the arrangement of the NPs into clusters on the GO surface and related with the magnetic properties. The development of composites involving organic coating has been widely studied to pursue the double objective of increasing NP/GO conjugation and improving the system biocompatibility. Extensive structural and functional characterization is carried out to understand the behavior of composites toward their performance as contrast agents in MRI., This work was financed by the Spanish National Plan of Research with projects CTQ2017-83632 and MAT2017-86616-R. C.D., G.T., A.B, J.F., and A.M.L.P. acknowledge the financial support from the Spanish MEC, through the Severo Ochoa Program for Centres of Excellence in R&D (SEV-2015-0496). This work (A.B.) has been done in the framework of the doctoral program “Chemistry” of the Universitat Autònoma de Barcelona. A.M.L.P. acknowledges the RyC-2012-11588 contract. A.B. acknowledges the FPI grant.

A new unsymmetric carborane-based dicarboxylic linker provided a 1D Cu

Supercritical CO2 (scCO2) technology is used here as an efficient method to assist in the preparation of a cutaneous polymeric formulation based on drug containing metal-organic framework composites. The supercritical fluid is used in three steps: (i) as a drying agent for the nanosized mesoporous matrix, (ii) as the impregnation vector of a topical antibiotic drug, and (iii) as a plasticizing and foaming fluid to obtain dispersions of the hybrid material into a biocompatible polymer, e.g., the macroporous patch. The materials were characterized using solid state techniques. The drug delivery and permeation profiles of the patches were investigated applying in vitro and ex vivo tests by using porcine skin. These analyses suggest that scCO2 impregnation is an easy and fast strategy to prepare composite devices able to progressively release and diffuse the incorporated drug throughout the skin, paving the way to efficiently prepare cutaneous devices for topical or systemic therapies., This work was supported by the Spanish Ministry of Science and Innovation MICINN through the Severo Ochoa Program for Centers of Excellence (CEX2019–000917-S) and the Spanish National Plan of Research with projects CTQ2017–83632 and PID2020–115631GB-I00 (Concepción Domingo, Ana M. López and Márta Kubovics). Sara Rojas and Patricia Horcajada acknowledge the regional Madrid founding (Talento 2017 Modality 2, 2017-T2/IND-5149), the MOFSEIDON project (PID2019–104228RB-I00, MCI/AEI/FEDER, UE), and the Multifunctional Metallodrugs in Diagnosis and Therapy Network (MICIU, RED2018–102471-T). Márta Kubovics acknowledge the financial support from the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie Cofund grant (agreement no MSCA-COFUND-DP/0320–754397). Patricia Horcajada acknowledges the Spanish Ramon y Cajal Programme (grant agreement no. 2014–16823). Sara Rojas acknowledges the Spanish Juan de la Cierva Incorporación Fellowship (grant agreement no. IJC2019–038894-I). This work has been done in the framework of the doctoral program “Chemistry” of the Universitat Autònoma de Barcelona by Márta Kubovics.

The development of nanostructured composites made of metal-organic frameworks (MOFs) and graphene-based components, including exfoliated nanoplates of graphene oxide (GO) or reduced (rGO) graphene oxide, is an area of great interest in gas storage and separation. To improve the industrial viability, it is commonly demanded to build these nanocomposites with the shape of compact units, such as monoliths, foams, pellets, or films. Methods to generate those 3D nanocomposites involving rGO are abundant; however, they become scarce when GO is the desired support due to the difficulty in maintaining the carbon matrix oxidized during the structuration process. In this work, a methodology based on the use of supercritical CO2 (scCO2) is described for the synthesis of nanocomposites involving a discontinuous MOF phase, e.g. nanoparticles (NPs) of HKUST-1, decorating the surface of a continuous GO matrix, with surface oxygen groups favoring MOF attachment. The use of this new supercritical methodology allows the nanostructuration of the composite in the form of 3D aerogels while avoiding the reduction of GO. Enhanced values of textural properties, determined by low-temperature N2 adsorption-desorption, were observed for the nanocomposites in comparison to the values calculated for similar physical mixtures, highlighting an increase of 40-45% in the value of the surface area for samples with a high percentage of HKUST-1. Moreover, the composite aerogels, displaying a type II isotherm, outperform pristine HKUST-1 in regard to the CH4 practical working capacity at high pressure. Particularly, a composite exhibiting more than 2-fold the working capacity of net HKUST-1 NPs was obtained. Columns involving the composite aerogel as the stationary phase were used to study the separation of N2/CO2 and CH4/CO2 gas mixtures. The results showed a high selectivity of the nanostructured HKUST-1@GO composites for CO2, with breakthrough times of ca. 20 min g-1 and stable cyclic operations., This work was supported by the Spanish Ministry of Science and Innovation MICINN through the Severo Ochoa Program for Centers of Excellence (SEV-2015-0496 and CEX2019-000917-S) and the Spanish National Plan of Research with projects CTQ2017-83632, PID2020-115631GB-I00, CTQ2016-75150-R, CTQ2017-84692-R, RTI2018-100832-B-I00, and PID2019-106832RB-I00. J.A.R.N. thanks Junta de Andalucia (P18-RT-612). K.C.S. thanks the Department of Chemistry through start-up funding. This work has been done in the framework of the doctoral program “Chemistry” of the Universitat Autònoma de Barcelona by A.R., A.B., and J.F.; A.R. and A.B. acknowledge FPI grants.

The increasing complexity in composition and structure of modern porous nanocomposite materials requires the development of advanced technologies that allow the simultaneous treatment of dissimilar compounds, not only with unlike composition but also involving different classes of pores, e.g., micro and mesopores. This work shows that supercritical CO2 (scCO2) technology can be used as generic processing aid to obtain composites involving non-reduced graphene oxide (GO) and metal organic frameworks (MOFs) in the form of aerogels with hierarchical porosity. Hybrid aerogels are formed by either depositing (ex situ) or growing (in situ) MOF nanocrystals onto the surface of 2D GO nanosheets. The archetypal hydrophilic HKUST-1 and UiO-66 and hydrophobic ZIF-8 microporous MOFs are chosen to exemplify the method possibilities. The ex situ route was adequate to prepare hydrophilic MOFs@GO homogeneous composites, while the in situ approach must be used to prepare hydrophobic MOFs@GO aerogels. Moreover, the scCO2 methodology should be adjusted for each studied MOF in regard of the organic solvent used to disperse the nanoentities constituting the composite. The end-products are obtained in the form of aerogels mimicking the shape of the recipient in which they are contained. The products are characterized in regard of structure by X-ray diffraction, textural properties by low temperature N2 adsorption/desorption and morphology by electronic microscopy., This work was supported by the Spanish Ministry of Science and Innovation MICINN through the Severo Ochoa Program for Centers of Excellence (SEV-2015-0496 and CEX2019-000917-S) and the Spanish National Plan of Research with projects CTQ2017-83632, PID2020-115631GB-I00. This work has been done in the framework of the doctoral program “Chemistry” of the Universitat Autònoma de Barcelona by A.B., A.R. and J.F.; A.B. and A.R. acknowledge FPI grants., With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).

Biofuels are considered sustainable and renewable alternatives to conventional fossil fuels. Biobutanol has recently emerged as an attractive option compared to bioethanol and biodiesel, but a significant challenge in its production lies in the separation stage. The current industrial process for the production of biobutanol includes the ABE (acetone-butanol-ethanol) fermentation process from biomass; the resulting fermentation broth has a butanol concentration of no more than 2 wt% (the rest is essentially water). Therefore, the development of a cost-effective process for separation of butanol from dilute aqueous solutions is highly desirable. The use of porous materials for the adsorptive separation of ABE mixtures is considered a highly promising route, as these materials can potentially have high affinities for alcohols and low affinities for water. To date, zeolites have been tested toward this separation, but their hydrophilic nature makes them highly incompetent for this application. The use of metal-organic frameworks (MOFs) is an apparent solution; however, their low hydrolytic stabilities hinder their implementation in this application. So far, a few nanoporous zeolitic imidazolate frameworks (ZIFs) have shown excellent potential for butanol separation due to their good hydrolytic and thermal stabilities. Herein, we present a novel, porous, and hydrophobic MOF based on copper ions and carborane-carboxylate ligands

Fine chemical and pharmaceutical companies often employ reactive crystallization or precipitation to make crystalline intermediates and finished products. In this work, the supercritical reactive crystallization route is used for the precipitation of diverse metal–organic frameworks (MOFs). 1D and 2D MOFs were obtained by reacting either bypyridil (two linking positions) or triazine (three linking positions)-based bridging molecules, respectively, with supercritical CO2 soluble M(hfacac)2 (where M = Zn2+ or Cu2+ and hfacac– stands for hexafluoroacetylacetonate). Additionally, miscellaneous reactions were designed for the crystallization of 3D MOFs in scCO2, embracing the precipitation of MIL-88B(Fe), ZIF-8, and a new Zn2+–curcumin coordination polymer. Obtained crystals in each case were analyzed from a morphological point of view by scanning electron microscopy analysis to elucidate potential formation mechanisms. The focus was on the obtained crystal habits at different reaction points, linked to the pr...

ZIF-8 nanometric particles are prepared via an environmentally friendly supercritical method aimed to minimize the environmental impact of current developed technologies for the synthesis of metal organic frameworks. In this synthetic process, CO 2 and ZIF-8 precursors are exclusively employed, avoiding the use of organic liquids, difficult to recover additives or large amounts of expensive ligand excess. The straight and high yield precipitation of empty-pore ZIF-8 nanopowder with tunable morphology was achieved. The powder was fully characerized in regard to the composition, structure, stability, morphology and textural properties. This work also focuses in the development of an eco-efficient method for the in situ polymerization of ethyleneimine inside the synthetized ZIF-8 pores, by using supercritical CO 2 as a solvent, reaction medium and catalyst for the aziridine ring-opening. The use of the prepared materials in CO 2 capture is assessed by analyzing CO 2 adsorption isotherms.

The supercritical carbon dioxide (scCO

We present the results of a combined experimental–molecular simulations approach concerning the capacity for CO2 adsorption of aminosilica hybrid products synthesized using supercritical fluids. Two porous supports were examined for amine functionalization, an ordered mesoporous silica (MCM-41) and a disordered silica gel (SG40). The textural properties of the studied materials were analyzed by low-temperature N2 adsorption–desorption isotherms and compared to those of molecular simulations using the grand canonical Monte Carlo simulation method. The CO2 adsorption capacity of these materials was evaluated by recording CO2 adsorption isotherms up to 100 kPa. Molecular simulations of the CO2 adsorption behavior of selected samples were performed to gain a fundamental understanding of the effect of functionalization. This study shows that in the functionalized materials, the distance between nitrogen atoms of the grafted amines is a critical factor for the occurrence of CO2 chemisorption, providing some ins...

The present work focuses on the development of a new eco-efficient chemical method for the polymerization of aziridine to hyperbranched polyethyleneimine (PEI) into mesoporous silica by using compressed CO2 as a solvent, reaction medium and catalyst. PEI was in situ grafted into MCM-41 and silica gel substrates, with pore diameters of 3.8 and 9.0 nm, respectively. The optimal polymerization conditions were found by varying the reaction pressure (1.0–10 MPa), temperature (25–45 °C) and time (20–400 min). The thermal stability analysis indicated that aminopolymer chains were covalently attached on the amorphous silica surface. The described compressed CO2 route for the synthesis of high amine content hybrid products (6–8 mmolN g−1) is a very fast method, with processing times in the order of few minutes even at very low working pressures (1.0 MPa), being a step forward in the design of efficient hybrid aminopolymer nanocomposites for CO2 capture. The adsorptive behavior of the prepared hybrid materials was experimentally established by recording the N2 (−196 °C) and CO2 (25, 50 and 75 °C) adsorption isotherms. Results were compared to molecular simulation studies performed using Grand Canonical Monte Carlo for either N2 or CO2 adsorbed on amino modified MCM-41, thus helping to elucidate the predominant PEI configuration present in the functionalized materials.

The current work builds on previous works on grafting of organosilanes on mesoporous silica supports using a supercritical CO2 anhydrous method, and it extends them by examining the capacity of supercritically prepared aminosilica hybrid products for CO2 adsorption and its separation from mixtures with other gases. The CO2 adsorption capacity under dry conditions of mesoporous silica gel and MCM-41 functionalized with a monoaminosilane was evaluated first by recording CO2 adsorption isotherms and next by performing microbalance cyclic adsorption/desorption experiments at 25 and 45 °C. CO2 adsorption and desorption rates were also studied as a function of the aminosilane loading. CO2 adsorption results were compared to similar data available in the literature, showing improved performance for the supercritically prepared products related to the CO2 adsorption efficiency and cyclic regenerability.

The present work examines the functionalization of silica supports via supercritical CO2 grafting of aminosilanes, which is an important step in the preparation of materials used as solid sorbents in CO2 capture. Four materials have been considered as solid supports: two commercially available silica gels (4.1 and 8.8 nm pore diameter), the mesoporous silica MCM-41 (3.8 nm pore diameter) and a microporous faujasite of the Y type. Mono- and di-aminotrialkoxysilane were chosen for this study. The optimal operating conditions required to have free aminosilane in solution were first evaluated by studying the phase behavior of the system scCO2/aminosilane at different pressures and temperatures. FTIR spectroscopy was used to determine the chemical structure of the grafted species. Aminosilane uptake was estimated by thermogravimetric and elemental analysis. Densities up to 3–4 molecules of monoaminosilane per nm−2 were reached by using a small amount of a cosolvent together with the supercritical CO2. The samples were characterized in regards of thermal stability, showing that aminosilane groups were covalently attached to the amorphous silica surface in the mesoporous supports, but not in the microporous zeolite. Low temperature N2 and ambient temperature CO2 isotherms were recorded to establish the adsorptive behavior of the prepared hybrid materials. The amine functionalized MCM-41 and the 8.8 nm silica gel exhibited a significant higher uptake of CO2 at low pressures compared with the bare supports. On the contrary, for the 4 nm silica gel and the zeolite the adsorption decreased after impregnation.

Materials that combine flexibility and open metal sites are crucial for myriad applications. In this article, we report a 2D coordination polymer (CP) assembled from CuII ions and a flexible meta-carborane-based linker [Cu2(L1)2(Solv)2]&bull, xSolv (1-DMA, 1-DMF, and 1-MeOH, L1: 1,7-di(4-carboxyphenyl)-1,7-dicarba-closo-dodecaborane). 1-DMF undergoes an unusual example of reversible phase transition on solvent treatment (i.e., MeOH and CH2Cl2). Solvent exchange, followed by thermal activation provided a new porous phase that exhibits an estimated Brunauer-Emmett-Teller (BET) surface area of 301 m2 g&minus, 1 and is capable of a CO2 uptake of 41 cm3 g&minus, 1. The transformation is reversible and 1-DMF is reformed on addition of DMF to the porous phase. We provide evidence for the reversible process being the result of the formation/cleavage of weak but attractive B&ndash, H∙∙∙Cu interactions by a combination of single-crystal (SCXRD), powder (PXRD) X-ray diffraction, Raman spectroscopy, and DFT calculations.

The controlled aggregation of copper oxide nanoparticles (CuO NPs) induced by a multitopic carboxylic acid allows the formation of mesoporous structures with high surface area, in the order of 100 m2 g−1, as demonstrated herein. The main novelty in the designed process is the use, as a previous step, of a sacrificeable monotopic carboxylate ligand for capping the CuO NPs. This step avoids the often observed unwanted behavior of uncontrolled aggregation and material densification. The monotopic 3,6,9-trioxadecanoate (HTODA) is used as the capping agent to prepare TODA@CuO, a starting material that forms colloidal dispersions in ethanol. For NPs self-assembly, the bulky tricarboxylic acid 4,4′,4′′,-benzene-1,3,5-triyl-tris(benzoic acid) (H3BTB) is chosen as an efficient interlinker in the controlled aggregation. The obtained mesoporous network shows a considerable thermal stability, retaining ≈70% of its specific surface area after annealing at 300 °C under vacuum. Thermal treatment involves TODA capping agent elimination, but not BTB linker. The simultaneous reduction of the CuO NPs to a Cu2O/Cu mixture is observed.

Density, vertical distribution and aggregation degree of soil microarthropod communities were studied between July and August of 1977 in the soils of three different plots, a forest and a pasture in Costa Rica.Data show the almost constant dominance of some groups of microarthropods (Isotomidae among the Collembola, Cryptostigmata among the Acarina and Symphila). There is a gradual decrease of density with depth, though not for all the groups, and a general tendency to an aggregate distribution.The hierarchical arder of densities of total microarthropod communities in the five localities was the following: maize, coffee, forest, manihot, and pasture. Se estudió durante los meses de julio y agosto de 1977, la densidad, distribución vertical y el grado de agregación de las poblaciones de micro artrópodos de los suelos de tres cultivos (Coffea arabica, Manihot utilissima, Zea mays), de un bosque, y de un pastizal en dos localidades del Valle Central de Costa Rica.Los datos obtenidos indican una dominancia casi constante de algunos grupos (Isotomidae en los colémbolos, Cryptostigmata en los ácaros y Symphila). Se nota también una gradual disminución de la densidad de los microartrópodos conforme aumenta la profundidad, aunque no para todos los grupos; finalmente se evidencia un estado de agregación más o menos fuerte.Le jerarquía en el orden descendiente de las densidades del total de microartrópodos en los cinco ambientes es la siguiente: maíz, café, bosque, yuca y pastizal.

Nanometric inorganic pigments are widely used as fillers for hybrid composite materials. However, these nanometric powders are hydrophilic in nature and their surface must be functionalized before use. In this work, titanium dioxide (TiO2) nanoparticles were coated using silane coupling agents with alkyl functionality. A supercritical carbon dioxide (scCO2) method was used for surface silanization. Five alkylalkoxysilanes with different alkyl chain length and structure were studied: methyltrimethoxy, isobutyltriethoxy, octyltriethoxy, octyldimethylmethoxy and octadecyltrimethoxysilane. The microstructure and thermal stability of deposited monolayers were characterized using thermogravimetric analysis, ATR–IR spectroscopy, transmission electron microscopy, wettability characterization and low-temperature N2 adsorption/desorption analysis. The use of scCO2 as a solvent provided an effective approach to functionalize individual inorganic nanoparticles due to the enhanced diffusivity of the solution molecules in the aggregates interparticle voids. The trifunctional silanes employed here yielded surfaces with better thermal stabilities and greater hydrophobicities than the used monofunctional silane.

scCO2 technology was used for the impregnation of microporous zeolites with organic molecules. Specifically, faujasite Y was impregnated with 1,3,5-triphenyl-2-pentene-1,5-dione that after reacting with the acid sites of the zeolite large cavities, formed the 2,4,6-triphenylpyrylium cation. Since the triphenylpyrylium cation has a size higher than the diameter of the zeolite channels, the fabrication method was considered as a ship-in-a-bottle procedure. To optimize the loading, different pressures and temperatures were tested in both the diffusion and cyclisation steps used in the impregnation supercritical process. The obtained impregnated samples were purified either by conventional Soxhlet extraction with dichloromethane or by cleaning with a scCO2 continuous flow. Loaded amounts of ca. 4–7 wt% were obtained following the supercritical procedure, which resulted more time-effective than the conventional procedure based in the use of organic solvents. Samples obtained were analyzed by thermal analysis, UV–vis and IR spectroscopy and characterization of surface area and micropore volume.

The objective of this ongoing work is to improve the physical properties of Portland cement pastes and Portland-composite cement pastes containing silica fume and/or fly ash through an accelerated carbonation process based on the use of SCCO2. Cement carbonation allows the preparation of cementitious composites reinforced with low-cost alkali-intolerant products and the use of these materials in solidification/stabilization of hazardous waste. In the supercritical treatment, results suggested that the carbonation rate of the portlandite phase slowed down after the first reaction stage and was overtaken by the reaction rate of the CSH and ettringite phases. Samples carbonated under the supercritical conditions developed a higher volume of gel pores than those obtained by natural carbonation. The microstructural analysis was completed by analyzing the water permeability of a cement paste/sand composite (mortar) after supercritical carbonation. Obtained values showed that supercritical carbonation reduced water permeability significantly

This study aims to analyze the effects of supercritical carbonation (CO2 at 20 MPa and 318 K) on the physicochemical properties of ordinary Portland cement pastes. The evolution of the main crystalline phases of the cement pastes during carbonation was determined by means of X-ray diffraction and thermogravimetric analysis. The pore structure was analyzed by low-temperature N2 adsorption−desorption and mercury intrusion porosimetry techniques. Finally, the microstructure of the samples was observed by using scanning electron microscopy coupled with energy-dispersive X-ray detection for chemical analysis. For a natural carbonation process, diffusion of CO2 into the pores of the cement paste is considered as the rate-controlling step. Instead, the accelerated reaction kinetics of calcium carbonate precipitation in the supercritical process was chemically controlled by the detachment of calcium ions from solid portlandite or CSH gel. The total pore volume of the studied cement pastes decreased with carbonation, which was associated with the deposition of the formed CaCO3. Samples carbonated under the supercritical conditions developed a higher volume of gel pores than those obtained by natural carbonation.

In this paper we present the precipitation of hydroxyapatite (HA), Ca 5 (OH)(PO 4 ) 3 , from highly concentrated CaCl 2 and K 2 HPO 4 solutions, carried out by a continuous method in a MSMPR reactor. The procedure consists of adding the reagents in a ratio Ca to P equal to 1.67, maintaining a temperature of 85°C, inert N 2 atmosphere inside the reactor, and monitoring and adjusting automatically the pH by means of a pH-stat system (pH =9.0 ± 0.1). Under these conditions HA with a Ca to P ratio equal or close to the stoichiometric composition (Ca/P = 1.667), with a high yield (up to 99%) and a high production rate (up to 1.17 g/l.min) is obtained at steady state. The CSD, morphology, crystallinity of the precipitates and impurities present fit the requirement for its biomedical applications.

A simple modification of a combustion method has been used for the production of ultraporous metals in air. Nitrates of different metallic elements were reacted with glycine as a reducing fuel. The glycine to nitrate ratio can be simply used to control the formation of oxides or, in the case of fuel-rich mixtures, the formation of metals such as Ni, Co, Cu or Ag. Furthermore, the metallic monoliths obtained present a remarkable porosity of fractal nature (from macro to nano scales) with pores ranging from many microns down to at least 5 nm. This exceedingly simple approach shows the way for the design and synthesis of complex porous microstructures of metals for the wide variety of applications where interface optimization is crucial. © 2013 The Royal Society of Chemistry., Partial funding from the Spanish Ministry MAT2011-28931 is acknowledged.

In this paper we present the precipitation of hydroxyapatite (HA), Ca 5 (OH)(PO 4 ) 3 , from highly concentrated CaCl 2 and K 2 HPO 4 solutions, carried out by a continuous method in a MSMPR reactor. The procedure consists of adding the reagents in a ratio Ca to P equal to 1.67, maintaining a temperature of 85°C, inert N 2 atmosphere inside the reactor, and monitoring and adjusting automatically the pH by means of a pH-stat system (pH =9.0 ± 0.1). Under these conditions HA with a Ca to P ratio equal or close to the stoichiometric composition (Ca/P = 1.667), with a high yield (up to 99%) and a high production rate (up to 1.17 g/l.min) is obtained at steady state. The CSD, morphology, crystallinity of the precipitates and impurities present fit the requirement for its biomedical applications.

Publicación versión online: 6 de agosto de 2007, This study aims to analyze the effects of supercritical carbon dioxide (SCCO2) on the carbonation of Portland cement pastes, with and without mineral addition. The process is based on the advantages of the low viscosity and surface tension of SCCO2 that allow the complete wetting of complex substrates with intricate geometries, including internal surfaces of agglomerates such of these found in cement pastes. The supercritical treatment alters the bulk chemical and structural properties of cement pastes by accelerating natural carbonation reactions, while at the same time it reduces both free and bound water. The observed overall effects of supercritical carbonation on Portland cement pastes were the neutralization of pore water alkalinity, the formation of calcium carbonate and the reduction in the Ca/Si ratio of the calcium silicate hydrate (CSH) gel. Moreover, the massive precipitation of calcium carbonate inside microcracks after supercritical treatment caused the refinement of the microstructure, thus, reducing water permeability to a large extent. Supercritical carbonation method can be completed in few hours, rendering it technically interesting. This work also contributes to the idea of increasing the durability of concrete by means of a preventive hydrophobic supercritical treatment against water ingress. A generic SCCO2 method for concrete silanization is proposed here., The financial support of EU Project STRP SurfaceT NMP2-CT-2005-013524 is greatly acknowledged. Carlos A. García-González gives acknowledgement to CSIC for its funding support through a I3P fellowship.

A study was conducted to evaluate long-term trends in nitrate concentrations and to try to identify the origin of nitrate using stable isotopes (15N(NO3-) and 18O(NO3-)) in the aquifers of the western Central Valley, Costa Rica, where more than 1 million people depend on groundwater to satisfy their daily needs. Data from 20 sites periodically sampled for 4 to 17 years indicate an increasing trend in nitrate concentrations at five sites, which in a period ranging from 10 to 40 years, will exceed recommended maximum concentrations. Results of isotopic analysis indicate a correspondence between land use patterns and the isotopic signature of nitrate in groundwater and suggest that urbanization processes without adequate waste disposal systems, followed by coffee fertilization practices, are threatening water quality in the region. We conclude that groundwater management in this area is not sustainable, and that land use substitution processes from agricultural activity to residential occupation that do not have proper sewage disposal systems may cause a significant increment in the nitrate contaminant load.

Poly(methyl methacrylate), PMMA, and of PMMA/Poly(epsilon-caprolactone), PCL, microspheres were loaded with different amounts of cholesterol by using a supercritical carbon dioxide (SC-CO2) impregnation process in order to use a clean technique with the absence of organic solvents, and to provide information for the infusion of additives into nonporous polymeric substrates. A conventional dissolution-evaporation method was also used to obtain PMMA and PMMA-PCL microparticles loaded with cholesterol. The obtained microspheres were characterized by environmental scanning electronic microscope, ESEM, nuclear magnetic resonance spectroscopy, NMR, and differential scanning calorimetry, DSC, thermal analysis. A comparison of drug release from particles obtained using both methods, the supercritical and the conventional, is presented.

11 pages, 5 figures, 3 tables., In this work a mechanism for the precipitation of chain-like calcite agglomerates is proposed and compared to those ones leading to nano- and microcalcite in the system Ca(OH)2–CO2–H2O. The experiments were carried out by semicontinuous carbonation of a slaked lime (Ca(OH)2) suspension at 20°C, 25°C and 30°C, fixing the suspension conductivity at 5 mS/cm. The processes at 20°C and 25°C were essentially similar except in the final stage. Basically, they both occurred via surface and were characterized by the initial precipitation of amorphous calcium carbonate followed by its crystallization into chain-like aggregates of calcite. These aggregates acted as an intermediate for the final products: spheroidal nanometric calcite at 20°C and submicrometric chain-like calcite agglomerates (similar to batons) at 25°C. On the other hand, at 30°C, the precipitation took place preferentially via solution, producing micrometric calcite of scalenohedral habit as final product. The change in the mechanism of precipitation from preferentially via surface (at 20°C and 25°C) to preferentially via solution (at 30°C) seems to be directly related to the availability of Ca(OH)2 surface in the reaction mixture during the first steps of precipitation., We acknowledge Cales de Llierca, SA for providing the slaked lime used in this work. Our research team belongs to the Excellence Research Team 99SGR-00207 financed by the Autonomous Government of the Generalitat de Catalunya, Spain.

The supercritical carbon dioxide synthesis of non-reduced graphene oxide (GO) aerogels from dispersions of GO in ethanol is here reported as a low-cost, efficient and environmentally friendly process. The preparation is carried out at the mild conditions of 333 K and 20 MPa. The high aspect ratio of the used GO sheets (ca. 30 μm lateral dimensions) allowed the preparation of aerogel monoliths by simultaneous scCO2 gelation and drying. Solid state characterization results indicate that a thermally stable mesoporous non-reduced GO aerogel was obtained by using the supercritical procedure, keeping the GO sheets most of the surface oxygenated groups, thus, facilitating further functionalization. Moreover, the monoliths have a very low density, high specific surface area and excellent mechanical integrity, characteristics which rivals with that of most light-weight reduced graphene aerogels reported in the literature., This work was financed by the Spanish National Plan of Research with projects CTQ2014-56324, CTQ2017-83632 and MAT2017-86616-R. C.D., G.T, A.B, G.G., S.S., J.F. and A.L.P. acknowledge the financial support from the Spanish MEC, through the Severo Ochoa Program for Centers of Excellence in R&D (SEV-2015-0496). This work (A.B.) has been done in the framework of the doctoral program "Chemistry" of the Universitat Autònoma de Barcelona. A.L.P. acknowledges the RyC-2012-11588 contract. A.B. acknowledges FPI grant. G.G. acknowledges the funding by EC H2020 under individual fellowship Marie Sklodowska-Curie (NANOTER, Grant Agreement 708351). P.M. and S.P. acknowledge the FCT/MCTES for respectively, a research contract under the Program Investigator (IF/00917/2013/ CP1162/CT0016) and PhD grant SFRH/BD/111515/2015; also UID/EMS/00481/2013-FCT and CENTRO-01-0145-FEDER-022083.

Las lombrices de tierra contribuyen a la generación de biomasa en la fauna, en conjunto con el nitrógeno (N) nutriente imprescindible para las plantas y animales este proceso contribuye a la fertilidad del suelo. De ahí la importancia del papel de las lombrices de tierra en el ciclo del N. Earthworms contribute to the generation of biomass in fauna, together with nitrogen (N), an essential nutrient for plants and animals, this process contributes to soil fertility. Hence the importance of the role of earthworms in the N cycle. Universidad Nacional, Costa Rica Escuela de Ciencias Biológicas

Biofuels are considered sustainable and renewable alternatives to conventional fossil fuels. Biobutanol has recently emerged as an attractive option compared to bioethanol and biodiesel, but a significant challenge in its production lies in the separation stage. The current industrial process for the production of biobutanol includes the ABE (acetone–butanol–ethanol) fermentation process from biomass; the resulting fermentation broth has a butanol concentration of no more than 2 wt% (the rest is essentially water). Therefore, the development of a cost-effective process for separation of butanol from dilute aqueous solutions is highly desirable. The use of porous materials for the adsorptive separation of ABE mixtures is considered a highly promising route, as these materials can potentially have high affinities for alcohols and low affinities for water. To date, zeolites have been tested toward this separation, but their hydrophilic nature makes them highly incompetent for this application. The use of metal–organic frameworks (MOFs) is an apparent solution; however, their low hydrolytic stabilities hinder their implementation in this application. So far, a few nanoporous zeolitic imidazolate frameworks (ZIFs) have shown excellent potential for butanol separation due to their good hydrolytic and thermal stabilities. Herein, we present a novel, porous, and hydrophobic MOF based on copper ions and carborane–carboxylate ligands, mCB-MOF-1, for butanol recovery. mCB-MOF-1 exhibits excellent stability when immersed in organic solvents, water at 90 °C for at least two months, and acidic and basic aqueous solutions. We found that, like ZIF-8, mCB-MOF-1 is non-porous to water (type II isotherm), but it has higher affinity for ethanol, butanol, and acetone compared to ZIF-8, as suggested by the shape of the vapor isotherms at the crucial low-pressure region. This is reflected in the separation of a realistic ABE mixture in which mCB-MOF-1 recovers butanol more efficiently compared to ZIF-8 at 333 K., L.G., P.G.F., F.T., C.V., and J.G.P. thank MINECO grant CTQ2016-75150-R and the Generalitat de Catalunya (2017/SGR/1720) for financial support. H.H. acknowledges financial support from the National Natural Science Foundation of China (No. 21978212). ICMAB receives support from the Spanish MINECO through the Severo Ochoa Centers of Excellence Program, under Grant SEV-2015-0496. L.G. is enrolled in the UAB Ph.D. program. L.G. acknowledges the China Scholarship Council (CSC) for his Ph.D. grant (201609110106). K.C.S. thanks the Department of Chemistry at Oregon State University for support through start-up funding. J.A.R.N. thanks MINECO and the UE Feder Program (project CTQ2017-84692-R). Some of the experiments were performed at the XALOC and NCD-SWEET beamlines of the ALBA synchrotron with the support of ALBA staff. We thank Bardiya Valizadeh for his assistance with measuring the contact angles