NEW HYBRID NANOSTRUCTURED ADSORBENT TYPE AMINE/KIT-6 FOR CO2 CAPTURE. The present work functionalized KIT-6 mesoporous material with aminopropyltrimethoxysilane (APTMS) and tested its efficiency in CO2 capture. The KIT-6 material was synthesized by hydrothermal method and functionalized via excess solvent in APTMS concentrations of 5 and 15% to obtain the hybrid adsorbents. All adsorbent materials were characterized by XRD, TGA/DTGA, DSC, N2 adsorption/desorption, SEM and applied in the CO2 capture, varying the temperature and pressure. The KIT-6 mesoporous structure at the hybrid adsorbents was kept. Variations in textural properties denoted that the organic molecules were incorporated in mesoporous structure. In the experiments, both chemisorption and physisorption were observed, reaching the best values at 25 ºC, indicating that the temperature influences the adsorption process. The experiments showed adsorbed amounts of up to 0.8 mmol/g at atmospheric pressure, displaying the efficiency of the chemisorption provided by the CO2 interaction with the hybrid adsorbents. At high pressures, a predominance of physisorption was observed, demonstrating a better performance for the KIT-6 support, due to the superior textural properties. Finally, a well-ordered and functional hybrid adsorbent was successfully developed for the adsorption of carbon dioxide.

Nesse trabalho, a oxidação catalítica do contaminante sulfeto em meio aquoso foi estudada na presença de carvão ativado na forma de briquetes mecanicamente resistentes e versáteis produzidos a partir de resíduos da indústria do vinho, i.e., semente e cachos. Caracterizações por microscopia eletrônica de varredura combinada com espectroscopia de dispersão de raios X (SEM/EDS), área superficial Brunauer-Emmett-Teller (BET), Raman, termogravimetria (TG), difração de raio X (XRD) e titulação potenciométrica indicam materiais com alta área mesoporosa e grande quantidade de grupos superficiais oxigenados. Esses briquetes mostraram alta atividade para a oxidação de sulfetos em meio aquoso, mesmo comparados com um carvão ativado comercial de elevada área superficial. A eficiência na oxidação de sulfeto é discutida em termos de dois efeitos: a elevada concentração de grupos superficiais redox do tipo quinona/hidroquinona formados a partir da decomposição do mosto da uva e a alta macro/mesoporosidade dos materiais que facilita a difusão das diferentes espécies durante a reação.

In this work, the catalytic oxidation of the hazardous and unpleasant aqueous sulfide contaminant was investigated by activated carbon in the form of mechanically resistant and versatile briquettes produced from two different wastes of the wine industry, i.e., lex and stalk. Characterization by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDS), surface area Brunauer-Emmett-Teller (BET), Raman, thermogravimetry (TG), X-ray diffractometry (XRD) and potentiometric titration showed that the materials have high mesoporous area with a large number of surface oxygen functionalities. These briquettes showed high efficiency for the oxidation of sulfides in aqueous medium, which is discussed in terms of two effects: the relatively high concentrations of quinone/hydroquinone surface redox groups formed from the grape must binder and the macro/mesoporosity, which facilitates the diffusion of the different species during the reaction.

Los carbones activados (CA) son materiales microporosos que poseen gran capacidad de adsorción. La heterogeneidad de cualquier adsorbente, en particular la de los CA, puede ser separada en dos grandes familias: energética (o superficial) y estructural. La heterogeneidad estructural es causada por la presencia de poros de diferentes tamaños y formas, y por su posible interconexión; mientras que la heterogeneidad energética se origina por las irregularidades superficiales, así como por la presencia de grupos funcionales y/o impurezas. En este trabajo se discutirán diferentes modelos de heterogeneidad superficial en materiales con poros de geometría, tipo placas paralelas, y su efecto sobre las isotermas de adsorción y en las distribuciones de tamaño de poros.

Activated carbons (AC) are microporous materials that have high adsorptive capacity. The heterogeneity of any adsorbent, in particular of the AC, can be separated into two large families: energetic and structural. Structural heterogeneity is caused by the presence of pores of different sizes, shapes and how they are interconnected, while the energy heterogeneity is caused by surface irregularities, as well as by the presence of functional groups and / or impurities. In this paper we discuss different models of surface heterogeneity in materials with slit pores and its effect on adsorption isotherms and the pore size distributions (PSD).

En este trabajo se prepararon dos carbones activados (CA), utilizando como agentes activantes ZnCl2 yK2CO3, denominados CA/ZnCl2,CA/K2CO3, respectivamente, a partir de residuos generados en el proceso de extracción del aceite esencial de candeia, árbol nativo de Brasil. Estos carbones se caracterizaron por microscopía electrónica de barrido, análisis termogravimétrico, análisis elemental, superficie específica por el método BET e índice de iodo. Estos materiales se probaron en la adsorción de dos moléculas modelos: el fenol y el azul de metileno, y se comparó su capacidad de adsorción con un carbón activado comercial (Merck), denominado CA/Com. Las isotermas de adsorción para CA/ZnCl2, CA/K2CO3 y CA/Com mostraron capacidades de adsorción máxima de 297, 228 y 271 mg g-1, para azul de metileno y de 109, 195 y 161 mg g-1, para el fenol, respectivamente. Los resultados evidenciaron que los carbones son eficientes en el proceso de adsorción de las moléculas modelo ensayadas. Las isotermas fueron ajustadas a las ecuaciones de Langmuir y de Freundlich. El modelo de Langmuir entregó un ajuste mejor, mostrando que los adsorbentes presentan superficies energéticamente más uniformes. Los carbones activados producidos se presentan como potenciales adsorbentes para compuestos orgánicos, agregando un valor adicional al residuo.

In this work, two activated carbons were prepared, using as activating agents ZnCl2 and K2CO3, denominated CA/ZnCl2,CA/ K2CO3, respectively, from waste generated in the process of extraction of essential oil of Candeia, a tree native of Brazil. These carbons were characterized by scanning electron microscopy, thermal analysis, elemental analysis, BET surface area and iodine index. These materials were tested in the adsorption of model molecules: Phenol and Methylene Blue, and a commercial activated carbon (Merck) was used for comparison purposes. Adsorption isotherms for CA/ZnCl2,CA/K2CO3 and CA/Com showed maximum sorption capacities of 297, 228 and 271 mg g-1 for Methylene Blue and 109,195 and 161 mg g-1 for phenol respectively. The results showed that the carbons are efficient in the adsorption process of molecules tested. The isotherms were fitted to equations of Langmuir and Freundlich. The Langmuir model provided better fit, showing that the adsorbents have energetically uniform surfaces. The materials produced were characterized as potential adsorbents for organic compounds that can be used as an alternative for obtaining activated carbons adding value to the residue.

Neste trabalho, foram preparados dois carvões ativados, utilizando como agentes ativantes o ZnCl² eoK2CO3, a partir de resíduos gerados no processo de extração de óleo essencial de Candeia, árvore nativa no Brasil. Estes carvões foram caracterizados por microscopia eletrônica de varredura, análise termo-gravimétrica, análise elementar, área superficial BET e índice de iodo. E testados na Adsorção das moléculas modelo: Fenol e Azul de Metileno, foi utilizado um carvão comercial (Merck) para fins de comparação. As isotermas de Adsorção para o CA/ZnCl2, CA/K2CO3 e CA/Com apresentaram capacidades máximas de adsorção de 297, 228 e 271 mg g-1 para Azul Metileno e de 109, 195 e 161 mg g-1 para fenol respectivamente. Os resultados evidenciaram que os carvões são eficientes no processo de adsorção das moléculas testadas. As isotermas foram ajustadas as equações de Langmuir e Freundlich, o modelo de Langmuir forneceu melhor ajuste, mostrando que os ad-sorventes apresentam superfícies energeticamente uniformes. Os materiais produzidos se caracterizaram como potenciais adsorventes para compostos orgânicos podendo ser utilizados como alternativa para obtenção de carvões ativados, além de agregar valor ao resíduo.

In this work, a TPR (Temperature Programmed Reduction) system is used as a powerful tool to monitor carbon nanotubes production during CVD (Chemical Vapour Deposition), The experiments were carried out using catalyst precursors based on Fe-Mo supported on Al2O3 and methane as carbon source. As methane reacts on the Fe metal surface, carbon is deposited and H2 is produced. TPR is very sensitive to the presence of H2 and affords information on the temperature where catalyst is active to form different forms of carbon, the reaction kinetics, the catalyst deactivation and carbon yields.

A series of activated carbons (AC) were prepared from waste of the olive oil production in the Cuyo Region, Argentine by two standard methods: a) physical activation by steam and b) chemical activation with ZnCl2. The AC samples were characterized by nitrogen adsorption at 77 K and evaluated for natural gas storage purposes through the adsorption of methane at high pressures. The activated carbons showed micropore volumes up to 0.50 cm³.g-1 and total pore volumes as high as 0.9 cm³.g-1. The BET surface areas reached, in some cases, more than 1000 m².g-1. The methane adsorption -measured in the range of 1-35 bar- attained values up to 59 V CH4/V AC and total uptakes of more than 120 cm³.g-1 (STP). These preliminary results suggest that Cuyo's olive oil waste is appropriate for obtaining activated carbons for the storage of natural gas.

Ferric chloride as a new activating agent was used to obtain activated carbons from agroindustrial waste. This material was prepared at three temperatures of pyrolysis, 200, 280 and 400 ºC. The carbonaceous materials obtained after the activation processes showed high specific surface areas (BET), with values higher than 900 m² g-1. The materials showed different behaviors in the adsorption of methylene blue dye and reactive red textile dye in water solutions. An important fact in the use of FeCl3 as an activating agent is that the activation temperature is at 280 ºC, well below of those commonly employed in chemical or physical activations described in the literature.

Neste trabalho, as vantagens de carbonos funcionalizados com alta área superficial e a forma especial de briquete foram combinadas para a produção de um novo adsorvente de metais. Análises BET, TG, IR, sítios ácidos e EDS sugerem que a funcionalização com HNO3 ocorre por todo o corpo do briquete. Foram estudadas também as isotermas e as cinéticas de adsorção de Cr3+, Zn2+ e do corante azul de metileno.

In this work, the advantages of special briquette shape and high surface area functionalized carbon were combined to produce a novel adsorbent for metals. BET, TG, IR, acid site and EDS analyses suggest that the functionalization with HNO3 and metal adsorption takes place throughout the briquette body. The adsorption isotherms and kinetics have been studied for Cr3+, Zn2+ and the dye methylene blue.