Production and characterization of activated carbon from wood wastes

Cedarwood (Cedrela Angustifolia) and teak (Tectona Grandis) woods are typically used for furniture manufacture because they have high durability, are light and easy to work. During these manufacturing process, large amount of these wastes is generated causing disposal environmental problems. In this paper, the residual wastes (sawdust) of Cedar (C) and Teak (T) are transformed into an activated material. The chemical composition of both biomass (C and T) was determinate by TGA (Thermogravimetric Analysis). Activated materials were characterized in surface area following the BET (Brunauer, Emmett and Teller) method, morphology using SEM (Scanning Electron Microscopy) and to know their functional groups a FTIR (Fourier Transform Infrared Spectroscopy) analysis was done. Their adsorption capacity was evaluated by removal of Methylene Blue (MB) and Congo Red (CR) from aqueous solutions. © Published under licence by IOP Publishing Ltd

Fascismo, crítica social y terrorismo. Un ensayo sobre el lenguaje instrumental y los medios de rotulación

Las Estados actuales legitiman su poder a partir del constante asedio que, en últimas, garantiza su propia razón de ser y justifica su barbarie. Terrorismo ha sido el rótulo indiscriminadamente atribuido a las corrientes progresistas que no renuncian a las posibilidades de liberación y cuyos argumentos se desvirtúan bajo falaces atribuciones de hechos lejanos a las palabras e intenciones. Este término se ha aplicado a aquellos críticos pensadores, malinterpretados –y muchas veces intencionalmente calumniados– por parte de sectores y grupos de corte fascista, que los hace objeto de acusación donde los acusados son siempre los perdedores, situación que ha contribuido a que la sociedad existente luche contra su propia posibilidad de liberación

Adsorption of arsenate on Fe-(hydr)oxide

Adsorption using metal oxide materials has been demonstrated to be an effective technique to remove hazardous materials from water, due to its easy operation, low cost, and high efficiency. The high number of oxyanions in aquatic ecosystems causes serious pollution problems. Removal of arsenate (H2AsO4 -), is one of the major concerns, since it is a highly toxic anion for life. Within the metal oxides, the iron oxide is considered as a suitable material for the elimination of oxyanions. The adsorption of H2AsO4 - on Fe-(hydr)oxide is through the formation of inner or outer sphere complexes. In this work, through computational methods, a complete characterization of the adsorbed surface complexes was performed. Three different pH conditions were simulated (acidic, intermediate and basic), and it was found that, the thermodynamic favourability of the different adsorbed complexes was directly related to the pH. Monodentate complex (MM1) was the most thermodynamically favourable complex with an adsorption energy of -96.0kJ/mol under intermediate pH conditions. © Published under licence by IOP Publishing Ltd

Dyes removal from water using low cost absorbents

In this study, the removal capacity of low cost adsorbents during the adsorption of Methylene Blue (MB) and Congo Red (CR) at different concentrations (50 and 100mg•L-1) was evaluated. These adsorbents were produced from wood wastes (cedar and teak) by chemical activation (ZnCl2). Both studied materials, Activated Cedar (AC) and activated teak (AT) showed a good fit of their experimental data to the pseudo second order kinetic model and Langmuir isotherms. The maximum adsorption capacities for AC were 2000.0 and 444.4mg•g-1 for MB and CR, respectively, while for AT, maximum adsorption capacities of 1052.6 and 86.4mg•g-1 were found for MB and CR, respectively. © Published under licence by IOP Publishing Ltd

Listado de los Bryozoa marinos del Caribe colombiano

The phylum Bryozoa is a significant aquatic invertebrate group owing to its diversity, abundance, wide distribution, and economic importance to humans. There are more than 5700 described Recent species within the phylum. Most of them are marine sessile species. They are present in all oceans, occupying a wide bathymetric range and colonize almost any type of substratum. The rich paleontological history of the phylum is reflected in abundant records from the Ordovician to the Recent and bryozoans are one of the dominant phyla in the Paleozoic fossil record (Camacho 1966, McKinney & Jackson 1991). Although bryozoans can be an important component of the benthic fauna, the average researcher is not very familiar with them, owing to their small size and the similarity of some species to corals, hydroids, seaweeds and sponges. In fact, the common names of bryozoans include “moss animals” and “lace corals” (Gordon & Mawatari 1992, Hayward & Ryland 1999).El Phylum Bryozoa es uno de los grupos de invertebrados acuáticos más importantes por su diversidad, abundancia, amplia distribución e importancia económica para el hombre. Actualmente existen alrededor de 5700 especies recientes descritas, la mayoría marinas y de vida sésil; se encuentran en todos los mares ocupando un amplio intervalo batimétrico y colonizando casi cualquier tipo de sustrato. Su rica historia paleontológica se refleja en abundantes registros que datan desde el Ordovícico hastael Reciente y lo convierten en uno de los phyla dominantes del registro fósil del Paleozoico (Camacho 1966, McKinney & Jackson 1991). A pesar de ser un componente importante de la fauna bentónica, resultan ser poco familiares para el investigador común debido al reducido tamaño de sus individuos y a su similitud externa que con otrosgrupos como corales, hidroides, algas y esponjas; de hecho, usualmente son conocidos como “animales musgo” y “corales encaje” (Gordon & Mawatari 1992, Hayward & Ryland 1999

A simple dilute-and-shoot approach for the determination of ultra-trace levels of arsenic in biological fluids via ICP-MS using CH3F/He as a reaction gas

The performance of a mixture of CH3F/He (1/9) as a reaction gas for the determination of As in biological fluids using a quadrupole ICP-MS instrument has been explored. A simple (dilute-and-shoot) interference-free method has been developed to quantify As concentrations at trace and ultra-trace levels in matrices with a high Cl content. As+ reacts with CH3F (through CH3F addition, followed by HF elimination) with high efficiency forming AsCH2 + as the primary reaction product, which can be monitored at a mass-to-charge ratio of 89, free from the Cl-based interferents (e.g., 40Ar35Cl+ and 40Ca35Cl+) that hamper the monitoring of 75As+. Matrix effects are overcome by the use of Te as an internal standard and the addition of 3% v/v ethanol to all samples and calibration standard solutions. The method presented was validated by analysing a set of reference materials (blood, serum and urine) and by assessing As recovery from a set of real blood samples. With this method, the limit of detection was calculated to be 0.8 ng L-1 As, favourably comparable to the vast majority of values reported in the literature, even with those obtained using more sophisticated sector-field instrumentation

El Tramo Corto de la Estructura a Plazo como Predictor de Expectativas de la Actividad Económica en Colombia

This article tests the hypothesis that the term structure of interest rates contains information about future economic activity in Colombia. According to the multilogit approach used to verify the hypothesis that an increase in the spread of interest rateEstructura a Plazo, Spread de Tasas de Interés, Diferencial de Inflación, Expectativas de Actividad Económica, Logit Ordenados

Límites culturales a la plena recepción del derecho moderno en Colombia : en torno a los orígenes coloniales de la cultura del incumplimiento.

This paper argues that the reception of modern law in Colombia failed to abolish or overcome a set of practices, relationships and social hierarchies of a historical period prior to Modernity. Thus a social context is preserved which, to a great extent, promotes a type of society and of right contrary to the foundations underlying the liberal political project and modern law. In this vein, this tradition based on custom constitutes an empirical limit to the full development of legal modernity in Colombia. This Pactist Tradition of colonialism, characterized by pacts between comparable forces and the flexible interpretation of legal norms, has permeated the evolution of modern law in Colombia to the point of naturalizing phenomena such as the growing culture of non-compliance with rules. This culture hinders the conditions for the possibility of a true and complete interference of the juridical forms within the processes of social transformation, creating a border between law and society, which considerably diminishes the guarantees that allow the formation of a democratic culture in Colombia.El presente trabajo sostiene que la recepción del derecho moderno en Colombia no logró abolir o superar un conjunto de prácticas, relaciones y jerarquías sociales propias de un periodo histórico previo a la Modernidad. Se conserva así un contexto social que en buena medida promueve un tipo de sociedad y de derecho contrario a las bases que fundamentaron el proyecto político liberal y el derecho moderno. En ese orden de ideas, dicha tradición basada en la costumbre constituye un límite empírico al pleno desarrollo de la modernidad jurídica en Colombia. Esta Tradición Pactista de origen colonial, caracterizada por los pactos entre fuerzas equiparables y la interpretación flexible de las normas jurídicas, ha permeado la evolución del Derecho Moderno en Colombia al punto de naturalizar fenómenos como la creciente cultura del incumplimiento de reglas. Esta cultura dificulta las condiciones de posibilidad de una verdadera y plena injerencia de las formas jurídicas en el interior de los procesos de transformación social, creando una frontera entre derecho y sociedad, la cual disminuye considerablemente las garantías que permiten la formación de una cultura democrática en Colombia

Elementos para una teoría crítica del derecho en colombia

La Constitución de 1991 supuso para Colombia el advenimiento de una renovada forma de entender las dinámicas jurídicas nacionales, abandonando la arcaica postura propia del formalismo positivista criollo2 y acogiendo un modelo constitucional de naturaleza abiertamente hermenéutica, asociado con una política de fortalecimiento del foro judicial como instancia de construcción de lo político (López, 2004). Sin embargo, un atento examen mostrará que buena parte de las promesas políticas y sociales que ambientaron la recepción del neoconstitucionalismo en Colombia han sido dramáticamente abandonada

Fascismo, crítica social y terrorismo. Un ensayo sobre el lenguaje instrumental y los medios de rotulación

Las Estados actuales legitiman su poder a partir del constante asedio que, en últimas, garantiza su propia razón de ser y justifica su barbarie. Terrorismo ha sido el rótulo indiscriminadamente atribuido a las corrientes progresistas que no renuncian a las posibilidades de liberación y cuyos argumentos se desvirtúan bajo falaces atribuciones de hechos lejanos a las palabras e intenciones. Este término se ha aplicado a aquellos críticos pensadores, malinterpretados –y muchas veces intencionalmente calumniados– por parte de sectores y grupos de corte fascista, que los hace objeto de acusación donde los acusados son siempre los perdedores, situación que ha contribuido a que la sociedad existente luche contra su propia posibilidad de liberación