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Antecedentes: la producción de papel está soportada principalmente en la madera debido a su alto contenido de celulosa. Sin embargo, actualmente se buscan fuentes alternativas que desestimulen el uso de este recurso favoreciendo la protección de los recursos naturales. La producción de cacao es una actividad económica importante en Colombia, sin embargo, genera grandes cantidades de residuos orgánicos. La cascarilla de cacao es uno de los residuos más significativos de la industria del cacao y representa alrededor del 12 % del peso total de la semilla. Objetivo: evaluar las propiedades fisicoquímicas del papel obtenido a partir de la cascarilla de cacao de la variedad TCS 01. Métodos: se identificó y cuantificó la composición de celulosa, hemicelulosa y lignina de la cascarilla de cacao. Se realizó un diseño experimental para analizar las condiciones de extracción y elaboración del papel obtenido de la celulosa de la cascarilla y se evaluaron seis parámetros de calidad basado en la norma NTC 5342 (muestreo para determinar la calidad de papel y cartón): adsorción, tensión, escritura, color, textura y apariencia. Resultados: se obtuvo un porcentaje de celulosa, hemicelulosa y lignina de 12,5, 21,5 y 15,6 % en peso respectivamente. A partir del diseño experimental para la elaboración del papel, se observó que a una temperatura de 80°C y durante 8 horas se obtuvo el mejor tratamiento, mostrando las mejores características de calidad y cumpliendo lo requerido por la NTC 5342. Se observó que la masa límite de celulosa fue de 4,21 g de muestra húmeda la cual tuvo una absorción de 3,5 ml de agua. Los ensayos de tensión mostraron resultados de 8,2 N en las muestras de papel. Conclusiones: aunque el material obtenido no cumple a cabalidad con las características necesarias para catalogarse como papel, este material puede ser utilizado en la producción de envases y embalajes donde se requiere resistencia mecánica moderada o en la producción del material llamado “cartón paja”. Además, su alta adsorción medida en la prueba realizada indica que este material podría ser utilizado como absorbente en las industrias alimentaria o de construcción. [ABSTRACT FROM AUTHOR]

This article describes the structural characterization of the husk of modified rice through the process of advanced oxidation with the reagent Fenton; the transformation was carried out with the intention of increasing the number of active sites on the material's surface, and consequently to generate an absorbent with a greater capacity for the removal of Cr (VI) ions in solution, compared to the husk of natural rice. The characterization of modified material was determined through distinct experimental techniques that include the analysis of the functional groups present on the absorbent's surface through infrared spectroscopy with diffuse reflectance, (DRIFT), likewise, a surface morphology analysis of the husk through a scanning electron microscope (SEM), a compositional analysis and thermogavimetric (TGA). All of these tests were carried out before and after the modification process. The results of the DRIFT point towards a slight shift and attenuation in the vibration frequencies of the functional groups implicated in the structural modification, whereas the SEM analysis indicated noticeable changes in the morphology of the absorbent material. Meanwhile, the compositional analysis showed considerable changes in the percentage of the material components, whose presence was confirmed through the TGA analysis, after decomposing at the expected temperatures. In short, all results confirm the structural modification of the absorbent tested. [ABSTRACT FROM AUTHOR]

Natural gas contains different types of gases such as methane, ethane, propane, butane, nitrogen and carbon dioxide, which methane is the main component. The separation of carbon dioxide from natural gas makes effective its use as domestic fuel, industrial and automotive fuel. The use of porous materials, which are able of preferentially adsorbing the CO2, is an alternative to obtain pure natural gas that allow the above mentioned applications. The traditionally used materials as CO2 adsorbents are activated carbon, zeolites and metal-organic frameworks (MOFs). In this paper, the CO2 adsorption capacity using zinc oxide nanoparticles (ZnONPs) is evaluated. These materials are attractive adsorbents, due to their low cost and great capacity of functionalization. [ABSTRACT FROM AUTHOR]

In this paper the removal of total organic carbon (TOC) present in an effluent generated by the rendering industry was evaluated, by photocatalysis (photo-Fenton) and activated carbon adsorption. The effluent considered in the study was the condensed steam cooking that has high environmental burdens so conventional biological and chemical treatments are insufficient or are economically unviable. To evaluate the effect of process variables, concentration of Fe (II) and dose of oxidizing agent (H2O2), the response surface methodology was used. In the adsorption study, the effect of pH, adsorbent dose and contact time was considered. For photocatalytic treatment the TOC removal percentage obtained was 69.2%, while for the adsorption process was 77.9%. After that, the TOC removal of two coupled systems was evaluated. For one of the systems, the effluent was pretreated by adsorption and subsequently subjected to photocatalytic treatment, reaching an overall degradation of 91.9%. This synergy between adsorption and photo-Fenton processes appears as a viable option for the treatment of this type of industrial effluents. [ABSTRACT FROM AUTHOR]

Air Conditioning with renewable energy is a key issue in the region's energy policy. The high temperatures usually attributed to climate change and the increase of the standard of living in society continues increasing energy demand in order to establish the conditions for thermal comfort in buildings. Solar air conditioning, although it contains a mature technology, its level of market introduction and acceptance by designers of buildings is exhaustive. This paper discusses the feasibility of these projects, identifies non-technological type barriers that hinders such use and implementation of solar energy for air conditioning systems, and finally, it approaches some criteria and recommendations to overcome these obstacles. [ABSTRACT FROM AUTHOR]

In this paper was studied the use of low-cost materials obtained from plants remains and modified organic matrices to replace the use of conventional methods for removal of heavy metals. So avoiding subsequent problems such as the generation of chemical sludge, and creates an alternative use for materials considered as waste. It is well known that the presence of some of the active components in these materials allow them to efficiently capture metal ions, however, it was found that other factors like pH of solution and concentration of metals also influence this process. In general, acid treatment and a subsequent transformation of materials to active carbon increases sorption capacity. Also, it is the pseudo second order model and the Langmuir isotherm that are the equations most used to describe kinetics and the adsorption behavior. [ABSTRACT FROM AUTHOR]

In recent years the asphaltene deposition of films on metal surfaces has been of great studies because they provide valuable information about the adsorption of asphaltene. This paper presents a study by light microscopy and scanning electron asphaltene films, grown on substrates of gold deposited on a surface electro brass. Samples were prepared with oil extracted asphaltene Ayacucho precipitated in n-hexane at a ratio (1:20) and various concentrations prepared by using as solvents: toluene, isopropyl benzene (cumene) and tetrahydrofuran. The deposition of the films was done using the technique of Spin Coating on the same conditions of speed and spin time. Finally we observed that asphaltene films prepared with cumene came the defect type "groove" with toluene, circular patterns were observed type "coffee rings" and finally diluted with tetrahydrofuran was presented on the surface discontinuity. [ABSTRACT FROM AUTHOR]

In this paper we identified the best conditions for the removal of Acid Blue 9 dye (AB9) using flower wastes (FW) as an adsorbent were determined using a full factorial 2³ and a Box-Behnken design for further optimization. Adsorbent dose (D), dye concentration (C) and contact time (t), were the assessed variables. The dye content was quantified by UV-Vis spectrometry. The statistical model presented an adequate adjustment coefficient (R² = 99,18%), allowing to achieve a removal of 98,5% with a dosage of 7,8 gL-1, dye concentration of 7,11 mgL-1 and contact time of 104 min. These results suggest that flowers wastes are an alternative and potential adsorbent material for the treatment of dissolved acid dyes. [ABSTRACT FROM AUTHOR]

An important oil production impact is the increase of environmental pollution due to discharge of water formation. This paper presents a study of oil adsorption onto hydrophobic silica, i.e., silica nanoparticles impregnated with Colombian vacuum residue (VR) at 2 and 4 wt% and onto zeolite and impregnated zeolite nanoparticles (2 and 4wt% of VR) to reduce the amount of O/W emulsion. The Langmuir and Freundlich adsorption models were used to fit the experimental information of the adsorption isotherms. Initial crude oil concentration ranges from 200 to 2000 mg/l. Oil concentration, after adsorption, was determined by using an UV-vis spectrophotometer. The highest oil removal was obtained with impregnated silica nanoparticles, yielding values of 200 mg/g, with 100% oil removal, 9 mg/g more than the value obtained by modified zeolite of 191 mg/g at the same initial concentration. Pseudo-first-order and pseudo-second-order models were used to fit the experimental data of the adsorption kinetics, with better results for the pseudo-second order model. [ABSTRACT FROM AUTHOR]

Benzothiazoles, such as benzothiazole (BT), 2-hydroxybenzothiazole (OHBT), and 2-methylbenzothiazole (MeBT) are toxic and poorly biodegradable organic compounds, frequently present in wastewater from rubber related applications. Activated carbon adsorption has been identified as an attractive treatment to removing those contaminants. This paper presents experimental results on the effect of chemical surface properties of activated carbon on the adsorption mechanism of benzothiazoles. Activated carbons with different surface chemical composition were prepared from a Filtrasorb-400 activated carbon. Pre-treatment of activated carbon included de-oxygenation and ozonation with different ozone doses. Experimental results showed that high surface concentration of oxygenated electron withdrawing groups produced a significant reduction on carbon adsorption capacity of benzothiazoles. The results suggest that adsorption mechanism of benzothiazoles would mainly take place by π-π dispersion interactions between the π-electrons of aromatic ring of benzothiazole molecules and the π-electrons of carbon graphene layers. When pH was higher than point of zero charge (pHPZC) of the activated carbon, repulsive electrostatic interactions appeared between adsorbate and ionised oxygenated surface groups, lowering the carbon adsorption capacity of benzothiazoles. [ABSTRACT FROM AUTHOR]

This paper compares experimental results on methylene blue (MB) removal systems based on ozone oxidation, zeolite adsorption, and simultaneous adsorption-oxidation using ozone in the presence of natural zeolite. The effect of pH (2-8), and the presence of radical scavengers (sodium acetate) on process rates and removal efficiencies are assessed at laboratory scale. The experimental system consisted of a IL differential circular flow reactor and an ozone generator rated at 5 g O3/h. Results show that ozone oxidation combined with zeolite adsorption increases the overall MB oxidation rate with respect to ozonation process and zeolite adsorption. In presence of free radical scavenger only a 25% of reduction on MB removal rate are observed in the simultaneous treatment, as compared with 70% when ozonation treatment is used, suggesting that MB oxidation reactions take mainly place on the zeolite surface. [ABSTRACT FROM AUTHOR]

This paper presents a study on the effects of some variables on the adsorption process of heavy metal ions in polluted wastewaters. The effects of pH, ion concentration, biomass concentration and pre-treatment of the biomass on the biosorption process of Pb2+, Cd2+ y Cr3+ in artificial solutions using non-living Saccharomyces cerevisiae were evaluated. It was observed that pH, biomass concentration and biomass pretreatment had a significant effect on the biosorption of Pb2+. For the adsorption of Cr3+ the only important factors were pH and concentration biomass, while for Cd2+ biosorption the effects of biomass concentration, pH and the presence of co-ions in the solution were significant. [ABSTRACT FROM AUTHOR]