Activación ácida de Bentonita para ser usada como agente decolorante de aceites vegetales

The design of various experiments in order to assess and simulate the effects of the acid activation of an Algerian bentonite on the bleaching capacity of Colza oil is described. Three key parameters of the acidic activation, namely acid concentration, contact time and temperature, were considered. The calculations made indicated that all variables display advantageous effects up to a certain level on the effectiveness of bleaching, regarded as the responsefunction. The acid concentration exerts a predominant individual effect as compared to the other parameters. Some small interactions between parameters were considered. High bleaching capacity reached 99% as optimal activation. Under accurate statistical measurements, synergy phenomena could be observed. Excessive activation is discussed in terms of loss in both porosity and acid strength.Se describe el empleo del diseño de experimentos con objeto de evaluar y simular los efectos de la activación ácida de bentonita procedente de Argelia en la decoloración de aceite de colza. Para ello se evaluaron tres variables: concentración de ácido, tiempo de contacto y temperatura. Empleando como variable respuesta la efectividad en el proceso de decoloración, los resultados obtenidos indicaron que las tres variables proporcionaban un efecto beneficioso hasta un determinado nivel, siendo la concentración de ácido, el factor que producía una mayor variación en la variable respuesta. Se observaron pequeñas interacciones entre los efectos estudiados. Se obtuvo un 99 % de capacidad para la decoloración como valor óptimo. El tratamiento estadístico realizado indicó la presencia de un efecto sinérgico. Una activación excesiva se puede explicar en términos de una pérdida de porosidad y fuerza ácida

Layered Lanthanide Sulfophosphonates and Their Proton Conduction Properties in Membrane Electrode Assemblies

Metal phosphonates containing acidic groups exhibit a wide range of proton conduction properties, which may enhance the performance of membrane electrode assemblies (MEAs). In this work, focus is placed on proton conduction properties of coordination polymers derived from the combination of lanthanide ions with a phosphonate derivative of taurine (2-[bis(phosphonomethyl)amino]-ethanesulfonic acid, H5SP). High-throughput hydrothermal screening (140 °C) was used to reach optimal synthesis conditions and access pure crystalline phases. Seven compounds with the composition Ln[H(O3PCH2)2−NH−(CH2)2−SO3]·2H2O were isolated and characterized, which crystallize in two different structures, monoclinic m-LaH2SP and orthorhombic o-LnH2SP (Ln = Pr, Nd, Sm, Eu, Gd, and Tb), with unit cell volumes of ∼1200 and ∼2500 Å3, respectively. Their crystal structures, solved ab initio from X-ray powder diffraction data, correspond to different layered frameworks depending on the Ln3+ cation size. In the orthorhombic series, o-LnH2SP, the sulfonate group is noncoordinated and points toward the interlayer space, while for m-LaH2SP, both phosphonate and sulfonate groups coordinate to the Ln3+ centers. As a consequence, different H-bonding networks and proton transfer pathways are generated. Proton conductivity measurements have been carried out between 25 and 80 °C at 70−95% relative humidity. The Sm3+ derivative exhibits a conductivity of ∼1 × 10−3 S·cm−1 and activation energy characteristic of a Grotthuss-type mechanism for proton transfer. Preliminary MEA assays indicate that these layered lanthanide sulfophosphonates assist in maintaining the proton conductivity of Nafion membranes at least up to 90 °C and perform satisfactorily in single proton-exchange membrane fuel cells.Proyectos MAT2016-77648-R del MINECO y P12-FQM-1656 de la Junta de Andalucía Proyectos PROTONCELL ENE2017-86711-C3-1-R y REPICOMES ENE2017-90932-REDT y MAT2016-81001-P

High Proton Conductivity in a Flexible, Cross-Linked, Ultramicroporous Magnesium Tetraphosphonate Hybrid Framework

Multifunctional materials, especially those combining two or more properties of interest, are attracting immense attention due to their potential applications. MOFs, metal organic frameworks, can be regarded as multifunctional materials if they show another useful property in addition to the adsorption behavior. Here, we report a new multifunctional light hybrid, MgH6ODTMP·2H2O(DMF)0.5 (1), which has been synthesized using the tetraphosphonic acid H8ODTMP, octamethylenediamine-N,N,N′,N′-tetrakis(methylenephosphonic acid), by highthroughput methodology. Its crystal structure, solved by Patterson-function direct methods from synchrotron powder Xray diffraction, was characterized by a 3D pillared open framework containing cross-linked 1D channels filled with water and DMF. Upon H2O and DMF removal and subsequent rehydration, MgH6ODTMP·2H2O (2) and MgH6ODTMP·6H2O (3) can be formed. These processes take place through crystalline−quasi-amorphous−crystalline transformations, during which the integrity of the framework is maintained. A water adsorption study, at constant temperature, showed that this magnesium tetraphosphonate hybrid reversibly equilibrates its lattice water content as a function of the water partial pressure. Combination of the structural study and gas adsorption characterization (N2, CO2, and CH4) indicates an ultramicroporous framework. High-pressure CO2 adsorption data are also reported. Finally, impedance data indicates that 3 has high proton conductivity σ = 1.6 × 10−3 S cm−1 at T = 292 K at ∼100% relative humidity with an activation energy of 0.31 eV.Proyecto nacional MAT2010-15175 (MICINN, España