Electroconductive Composites from Polystyrene Block Copolymers and Cu–Alumina Filler

Technological advancements and development of new materials may lead to the manufacture of sustainable energy-conducting devices used in the energy sector. This research attempts to fabricate novel electroconductive and mechanically stable nanocomposites via an electroless deposition (ELD) technique using electrically insulating materials. Metallic Cu is coated onto Al2O3 by ELD, and the prepared filler is then integrated (2–14 wt %) into a matrix of polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene-graft-maleic anhydride (PS-b-(PE-r-B)-b-PS-g-MA). Considerable variations in composite phases with filler inclusion exist. The Cu crystallite growth onto Al2O3 was evaluated by X-ray diffraction (XRD) analysis and energy dispersive spectrometry (EDS). Scanning electron microscopy (SEM) depicts a uniform Cu coating on Al2O3, while homogeneous filler dispersion is exhibited in the case of composites. The electrical behavior of composites is enhanced drastically (7.7 × 10−5 S/cm) upon incorporation of Cu–Al2O3 into an insulating polymer matrix (4.4 × 10−16 S/cm). Moreover, mechanical (Young’s modulus, tensile strength and % elongation at break) and thermal (thermogravimetric analysis (TGA), derivative thermogravimetry (DTG), and differential scanning calorimetry (DSC)) properties of the nanocomposites also improve substantially. These composites are likely to meet the demands of modern high-strength electroconductive devices

BPPO-Based Anion Exchange Membranes for Acid Recovery via Diffusion Dialysis

To reduce the environmental impact of acids present in various industrial wastes, improved and robust anion exchange membranes (AEMs) are highly desired. Moreover, they should exhibit high retention of salts, fast acid permeation and they should be able to operate with low energy input. In this work, AEMs are prepared using a facile solution-casting from brominated poly-(2,6-dimethyl-1,4-phenylene oxide) (BPPO) and increasing amounts of 2-phenylimidazole (PI). Neither quaternary ammonium salts, nor ionic liquids and silica-containing compounds are involved in the synthesis. The prepared membranes showed an ion exchange capacity of 1.1–1.8 mmol/g, a water uptake of 22%–47%, a linear expansion ratio of 1%–6% and a tensile strength of 0.83–10.20 MPa. These membranes have potential for recovering waste acid via diffusion dialysis, as the acid dialysis coefficient (UH) at room temperature for HCl is in the range of 0.006–0.018 m/h while the separation factor (S) is in the range of 16–28, which are higher than commercial DF-120B membranes (UH = 0.004 m/h, S = 24)

Selective heavy metal removal and water purification by microfluidically-generated chitosan microspheres: Characteristics, modeling and application

Many industrial wastewater streams contain heavy metals, posing serious and irreversible damage to humans and living organisms, even at low concentrations due to their high toxicity and persistence in the environment. In this study, high-performance monodispersed chitosan (CS) microspheres were prepared using a simple microfluidic method and evaluated for metal removal from contaminated water. Batch experiments were carried out to evaluate the adsorption characteristics for the removal of copper ions, one representative heavy metal, from aqueous solutions. The inherent advantages of microfluidics enabled a precise control of particle size (CV = 2.3%), while exhibiting outstanding selectivity towards target ions (adsorption capacity 75.52 mg g−1) and fair regeneration (re-adsorption efficiency 74% after 5 cycles). An integrated adsorption mechanism analytic system was developed based on different adsorption kinetics and isotherms models, providing an excellent adsorption prediction model with pseudo-second order kinetics (R2 = 0.999), while the isotherm was fitted best to the Langmuir model (R2 = 0.998). The multi-step adsorption process was revealed via quantitative measurements and schematically described. Selective adsorption performance of CS microspheres in the present of other competitive metal ions with different valence states has been demonstrated and studied by both experimental and density functional theory (DFT) analysis

Modification of the lignin structure during alkaline delignification of eucalyptus wood by kraft, soda-AQ, and soda-O2 cooking

11 páginas.-- 5 figuras.-- 4 tablas.-- 50 referencias.-- Supporting Information The general conditions for the kraft, soda-AQ, and soda-O2 alkaline cooking of eucalyptus feedstock, are shown in Table S1. The identification and relative molar abundance of the compounds identified in the Py-GC/MS of MWL from eucalyptus wood, and residual and black liquor lignins from kraft, soda-AQ,and soda-O2 pulping at different kappa numbers, are listed in Table S2. This material is available free of charge via the Internet at http://pubs.acs.org/doi/suppl/10.1021/ie401364dThe modification of the lignin structure of an eucalyptus feedstock during alkaline delignification by kraft, soda-AQ, and soda-O2 cooking processes has been investigated by different analytical techniques (size exclusion chromatography (SEC), pyrolysis gas chromatography-mass spectroscopy (Py-GC/MS), 1H-13C two-dimensional nuclear magnetic resonance (2D-NMR), and 31P NMR). The characteristics of the lignins were compared at different pulp kappa levels, and with the native lignin isolated from the wood. The structural differences between the kraft, soda-AQ, and soda-O2 residual lignins were more significant at earlier pulping stages. At the final stages, all the lignin characteristics were similar, with the exception of their phenolic content. Strong differences between lignins from pulps and cooking liquors were observed, including enrichment in guaiacyl units in pulp residual lignin and enrichment in syringyl units in black liquor lignin. A comparison of the alkaline cookings indicate that soda-O2 process produced higher lignin degradation and provided promising results as pretreatment for the deconstruction of eucalyptus feedstocks for subsequent use in lignocellulose biorefineries. © 2013 American Chemical Society.This study has been funded by the EU-Project LIGNODECO (No. KBBE-244362), the Spanish project (No. AGL2011-25379), and the CSIC project (No. 201040E075). Dr. Rencoret thanks the CSIC for a JAE-DOC contract in the program “Junta para la Ampliación de Estudios”, cofinanced by Fondo Social Europeo (FSE). Finally, we thank Suzano Papel e Celulose (Brazil) for providing the pulp and black liquor samples from the alkaline cooking experiments and the corresponding additional data.Peer Reviewe

Composición química de diversos materiales lignocelulósicos de interés industrial y análisis estructural de sus ligninas

Memoria del proyecto desarrollado durante el período de investigación del Master en “Estudios Avanzados en Química”.Las plantas son materiales lignocelulósicos. Constituyen principalmente en celulosa, hemicelulosas y lignina. La composición química y la morfología de la pared celular están relativamente bien conocidos. Sin embargo las características estructurales de sus biopolímeros, sobretodo de lignina en relación con su biosíntesis y con la funcionalidad en la pared celular no han sido investigado tan extensivamente (sobretodo de especies herbáceas). La estructura de celulosa es universal y bien conocido, sin embargo se desconoce en gran parte los mecanismos de su organización estructural y plegamiento en las paredes celulares (láminas de microfibrillas). Estos conocimientos podrían cambiar drásticamente las estrategias para aumentar el aprovechamiento lignocelulósico mediante técnicas de biorrefinería. Actualmente el contenido y la estructura de lignina y su entrecruzamiento con polisacáridos son factores limitantes en el aprovechamiento lignocelulósico. En procesos con biomasa se requieren pretratamientos optimizados para aumentar la accesibilidad de enzimas hidrolíticas a los polisacáridos, por ejemplo para aumentar el rendimiento de sacarificación con el fin de producir biocombustibles o para conversión en otros productos (por ejemplo por fermentación). Por ello se debe conocer los cambios estructurales de la lignina durante el proceso. Pueden servir muy bien los conocimientos de las técnicas analíticas usadas para estudiar la lignina durante la fabricación de papel. Un pretratamiento idóneo sería el fraccionamiento completo de celulosa, hemicelulosa y lignina y su conversión en productos puros aumentando la viabilidad económica de plantas de biomasa y la descarbonización del suministro de materias primas y energía.Peer reviewe

Caracterización química y estructural de lignina y lípidos de materiales lignocelulósicos de interés industrial

The present Thesis includes the following sections: i) an introduction to the constituents of lignocellulosic materials, with a focus on the lignin and lipophilic extractives, and the utilization of these materials in industrial processes; ii) the main objectives of the Thesis; iii) a detailed description of the materials and methods used; iv) the corresponding references cited; v) the main results obtained and their discussion, which are presented as scientific publications; and finally vi) the main conclusions drawn from the results.In the present PhD Thesis, the chemical composition of diverse lignocellulosic materials, including fast growing eucalypt trees (woody) and elephant grass crops (non-woody) as well as agricultural residues (wheat straw) was studied. Special emphasis was put on the composition and structural characteristics of the lignin and lipophilic extractives, which play a decisive role in the industrial processes of these materials. On the other hand, the structural modifications of the lignin from eucalypt wood during different alkaline deconstruction processes were studied. This information constitutes an important starting point in order to optimize biorefinery processes, particularly in the cooking processes used for the production of cellulose pulp or in the production of bioethanol.Este trabajo se ha llevado a cabo en el Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNASCSIC). Ha sido financiado por una beca FPI del Ministerio de Educación y Ciencia, asignada al proyecto de investigación ´Utilización de cultivos agrícolas y forestales para la producción de pasta de papel: Tratamientos enzimáticos para la eliminación de lípidos y lignina´ (AGL2008-00709), y por el proyecto europeo ´Optimised pre-treatment of fast growing woody and nonwoody Brazilian crops by detailed characterisation of chemical changes produced in the lignin-carbohydrate matrix (LIGNODECO)´ (KBBE-244362).Peer reviewe

Lipophilic extractives from the cortex and pith of elephant grass (Pennisetum purpureum Schumach.) stems

The composition of lipophilic extractives in the cortex and pith of elephant grass (Pennisetum purpureum Schumach.) stems was thoroughly studied by gas chromatography-mass spectrometry. The predominant compounds were fatty acids followed by sterols (in free and conjugated forms as esters and glycosides). Other steroid compounds, as steroid hydrocarbons and ketones, were also present. Additionally, important amounts of mono-, di-, and triglycerides were identified. Other aliphatic series such as n-alkanes, n-fatty alcohols, and n-alkyl ferulates, together with tocopherols and a series of high molecular weight esters, were also found, although in minor amounts. The analyses also revealed the presence of a β-diketone (12,14-tritriacontanedione), which was particularly abundant in the cortex. Finally, two lignans, matairesinol and syringaresinol, were also detected. In general terms, the abundances of the different classes of compounds were higher in the pith, except for the series of n-fatty alcohols, n-alkyl ferulates, β-diketones, and lignans, which were more prominent in the cortex.Peer Reviewe