Biochar-MgO from Soursop Seeds in the Production of Biofuel Additive Intermediates.

The conversion of residual biomass from fruit seeds into biochar can be achieved using MgCl2 as an activating agent and calcining at 700 °C. The resulting MgO-biochars were employed in the aldol condensation reaction between furfural and acetone. This reaction is essential as the first step in the obtention of biofuels derived from biomass. The biochars were characterized through various physicochemical techniques, revealing that the presence of MgO nanoparticles deposited on the carbon surface modifies the structural and acidic-basic properties of the carbonaceous materials with a graphitic structure. The biochar with a surface content of MgO of 0.34 % w/w enables the achievement of 100 % of selectivity towards 4-(2-furanyl)-3-buten-2-one (I) with quantitative conversions under optimized conditions. This property highlights the potential of using this type of biochar, commonly used for CO2 capture, as a versatile acidic-basic catalyst, thereby introducing a novel approach to sustainable chemistry.

Kinetic study of CO2 adsorption of granular-type activated carbons prepared from palm shells.

The adsorption kinetics of activated carbon (AC)-type adsorbent materials, which were prepared from a by-product of African palm (shells) processing by chemical activation with dehydrating metal salts at two different concentrations, was studied. N2 physisorption was performed in order to determine the textural characteristics of the adsorbent solids, obtaining materials with BET areas between 721 and 1334 m2g-1 and micropore volumes between 0.33 and 0.55 cm3g-1; FTIR determination was also used as a chemical characterization technique in order to observe variations in the functional groups present. CO2 adsorption was determined, obtaining values between 175 and 274 mg∙g-1; these results are correlated with the physicochemical characteristics of the materials. With the experimental data obtained in this adsorption, the kinetic study was carried out taking into account the kinetic models of pseudo-first-order, pseudo-second-order, and intraparticle diffusion, showing a better adjustment to this last model of a physisorption process. Finally, CO2 adsorption calorimetry was performed on the two adsorbents that presented the highest adsorption capacities, evidencing variations in the characteristics of the activated carbons with the change of the impregnant used. A correlation is observed between the speed of the CO2 adsorption process and the adsorption capacity.

Materiales carbonosos preparados a partir de cuesco de palma en la adsorción de CO2. Caracterización elemental, próxima y morfológica / Carbonaceous materials prepared from Palm shells for the adsorption of CO2. Elemental, proximal, and morphological characterization / Materiais carbonosos preparados a partir de Cuesco de Palma en a adsorção de CO2. Caracterização elementar, proximal e morfológica

Resumen En la presente investigación se prepararon sólidos porosos tipo carbón activado (CA) a partir de la activación química del cuesco de palma africana procedente de los cultivos de la región de la Guajira, Colombia, con soluciones de Fe(NO3)3 y Cu(NO3)2 con cambio en la concentración a dos diferentes temperaturas: 973 y 1073 K. Los sólidos adsorbentes preparados se caracterizaron para determinar sus propiedades fisicoquímicas y capacidades de adsorción de CO2. Los CA obtenidos presentan micro mesoporosidad con áreas superficiales entre 5 y 1300 m2g-1. Los valores con respecto al contenido de carbono fijo se encuentran entre 47,1 y 78,4%; los resultados evidencian que el proceso de activación tiene efectos sobre los parámetros texturales, composición elemental y proximal de los sólidos obtenidos. También se realizó la caracterización morfológica de la superficie de los materiales con SEM evidenciando la formación de mayor rugosidad en las muestras activadas a 1073 K, específicamente, los carbones activados con el nitrato cúprico; además, mediante EDX se cuantificó la presencia de algunos elementos. Los valores obtenidos de la adsorción de CO2 a bajas presiones se encuentran entre 80 y 250 mg•g-1, evidenciándose una mayor afinidad hacia los sólidos adsorbentes (MCu3 y MFe5).

Abstract In the present investigation, porous solids type activated carbon (CA) were prepared from the chemical activation of the African palm shells from the crops of the Guajira region, Colombia, with solutions of Fe(NO3)3 and Cu(NO3)2 with change in concentration at two different temperatures: 973 and 1073 K. The prepared adsorbent solids were characterized to determine their physicochemical properties and CO2 adsorption capacities. The CAs obtained present micro-mesoporosity with surface areas between 5 and 1300 m2g-1. The values with respect to the fixed carbon content are between 47.1% and 78.4%; the results show that the activation process has effects on the textural parameters, elemental and proximal composition of the solids obtained. The morphological characterization of the surface of the materials was also carried out with SEM, evidencing the formation of greater roughness in the samples activated at 1073 K, specifically, the activated carbons with cupric nitrate; furthermore, the presence of some elements was quantified by EDX. The values obtained from the adsorption of CO2 at low pressures are between 80 and 250 mg•g-1, showing a greater affinity towards adsorbent solids (MCu3 and MFe5).

Resumo Na presente investigação, sólidos porosos do tipo carvão ativado (CA) foram preparados a partir da ativação química do Cuesco de Palma Africana de lavouras da região de Guajira-Colômbia com soluções de Fe(NO3)3 e Cu(NO3)2 com alteração em concentração em duas temperaturas diferentes 973 e 1073 K. Os materiais preparados foram caracterizados para avaliar suas propriedades físico-químicas e capacidades de adsorção de CO2. Os (CAs) obtidos apresentam micro-mesoporosidade com áreas superficiais entre 5 e 1300 m g-1. Os valores com relação ao teor de carbono fixo estão entre 47,1 - 78,4%, os resultados mostram que o processo de ativação tem efeitos nos parâmetros texturais, composição elementar e proximal dos sólidos obtidos. A caracterização morfológica da superfície dos materiais também foi realizada com MEV, evidenciando a formação de maior rugosidade nas amostras ativadas a 1073 K, especificamente os carbonos ativados com nitrato cúprico, e a presença de alguns elementos foi quantificada por EDX. Os valores obtidos na adsorção de CO2 em baixas pressões estão entre 80-250 mg•g-1, mostrando uma maior afinidade para sólidos adsorventes (MCu3 e MFe5).

Adsorption of CO2 on Activated Carbons Prepared by Chemical Activation with Cupric Nitrate.

Activated carbons were prepared from a lignocellulosic material, African palm shells (Elaeis guineensis), by chemical impregnation of the precursor with solutions of 1-7% w/v Cu(NO3)2 at five different concentrations. These were carbonized in a carbon dioxide atmosphere at 1073 K to obtain different carbons. Their textural properties were characterized by nitrogen and carbon dioxide adsorption isotherms in order to evaluate the pore-size distribution. The immersion enthalpies of the activated carbons in benzene, dichloromethane, and water were determined. The CO2 adsorption capacities of the materials at 273 K under low-pressure conditions were also determined. Chemical characterization was performed by mass spectrometry, Fourier transform infrared spectroscopy, and temperature-programmed reduction. With this method of preparation under the concentrations described, activated micro-mesoporous carbons were obtained, with the formation of highly mesoporous solids that favored the process of diffusion of molecules of CO2 into the material. Here, we show that activated carbons were obtained with different textural characteristics: surface Brunauer-Emmett-Teller areas varied between 473 and 1361 m2 g-1 and micropore volume between 0.18 and 0.51 cm3 g-1. The activated carbon with the highest values of textural parameters was ACCu5-1073. Micro-mesoporous solids were obtained with the methodology used. This is important as it may help the entry of CO2 molecules into the pores. The adsorption of CO2 in the materials prepared presented values between 103 and 217 mg CO2 g-1; the values of volume of narrow microporosity obtained were between 0.16 and 0.45 cm3 g-1. The solid with the greatest capacity for adsorption of CO2 and volume of narrow microporosity was ACCu3-1073. The use of these solids is of importance for future practical and industrial applications. The adsorption kinetic of CO2 in the activated carbons prepared with metallic salt of copper is in good accordance with the intraparticle diffusion model, for which diffusion is the rate-limiting step. The adsorption of CO2 in the prepared activated carbons is favorable from the energy and kinetic point of view, as these accompanied by the presence of wide micro-mesoporosity favor the entry of CO2 into the micropores.

Caracterización textural y química de carbones activados preparados a partir de cuesco de palma africana (Elaeis guineensis) por activación química con CaCl2 y MgCl2 / Textural and chemical characterization of activated carbon prepared from shell of african palm (Elaeis guineensis) by chemical activation with CaCl2 and MgCl2 / Caracterização textural e química de carvões ativados prearados a partir de casca da palmeira africana (Elaeis guineensis) por ativação química com CaCl2 y MgCl2

Se obtuvieron carbones activados mediante activación química de cuesco de palma africana (Elaeis Guineensis) con soluciones de cloruro de magnesio y cloruro de calcio a diferentes concentraciones. Los materiales preparados se caracterizaron textural y químicamente. Los resultados obtenidos muestran que los carbones activados con los mayores valores de área superficial y volumen de poro se obtienen cuando se emplean soluciones con las menores concentraciones del agente activante. Los carbones activados obtenidos presentan áreas superficiales y volúmenes de poro con valores entre 10 y 501 m²/g y 0,01 y 0,29 cm³/g respectivamente. Los valores de las entalpías de inmersión de los sólidos en agua se encuentran entre -14,3 y -32,8 J/gy en benceno entre -13,9 y -38,6 J/g. La acidez y la basicidad total de los carbones activados presentan valores entre 23 y 262 µmol/g y 123 y 1724 µmol/g respectivamente. También se determinó el pH en el punto de carga cero, con valores entre 4,08 y 9,92 para el conjunto de los carbones activados. Los resultados muestran que la activación con las sales MgCl2 y CaCl2 producen carbones activados con poros en el rango de los mesoporos que facilitan la entrada del adsorbato al interior del material.

Activated carbons through chemical activation of African palm shells (Elaeis guineensis) with magnesium chloride and calcium chloride solutions at different concentrations were obtained. The prepared materials were characterized textural and chemically. The results show that activated carbons with higher values of surface area and pore volume are obtained when solutions with lower concentrations of the activating agent are used. The obtained activated carbons have surface areas and pore volumes with values between 10 and 501 m²/g and 0.01 and 0.29 cm³/g respectively. Immersion enthalpies values of solids in water were between -14.3 and -32.8 J/g and benzene between -13.9 and -38.6 J/g. Total acidity and basicity of the activated carbons had values between 23 and 262 μmol/g 123 and 1724 μmol/g respectively. pH at the point of zero charge was also determined with values between 4.08 and 9.92 for set of activated carbons . The results show that activation with CaCl2 and MgCl2 salts produce activated carbons with pores in the range of mesopores for facilitate entry of the adsorbate into the materials.

Carvões ativados por ativação química a partir da casca de palmeira africana (Elaeis guineensis) com soluções de cloreto de magnésio e cloreto de cálcio em diferentes concentrações foram obtidas. Os materiais preparados foram caracterizados pela textura e quimicamente. Os resultados obtidos mostram que os carvões ativados com maiores valores de área superficial e volume de poros se conseguem usando baixas concentrações do ativante. Os carvões ativados obtidos têm áreas superficiais e volumes de poro com valores entre 10 e 501 m²/g e 0,01 e 0,29 cm³/g , respectivamente. Os valores da entalpia de imersão do sólido em água situam-se entre -14,3 e -32,8 J/g e em benzeno entre -13,9 e -38,6 J/g . A acidez e basicidade total dos carvões ativados obtidos apresentam valores entre 23 e 262 μmol/g e 123 e 1724 μmol/g, respectivamente. O pH no ponto de carga zero também foi determinado com valores entre 4,08 e 9,92 para todos os carvões ativados. Os resultados mostram que a ativação com CaCl2 e MgCl2 produze carvões ativados com poros na gama de mesoporos que facilitam a entrada do adsorbato para os materiais.

Clinical aspects of intestinal neuronal dysplasia.

PURPOSE: The aim of this study was to determine the presence of specific clinical symptoms in intestinal neuronal dysplasia (IND) and whether it correlates to the severity of histopathologic findings. METHODS: A group of 44 severe IND and a group of 16 mild IND patients diagnosed by means of a histochemical rectal biopsy were compared with a group of 37 patients with functional constipation (FC) with normal rectal biopsy results. RESULTS: Patients with severe IND began their symptoms at an earlier age than those with mild IND and FC (5.2 +/- 112 months v 17.5 +/- 23 months and 22.5 +/- 21.8 months, respectively; P <.001). The presence of intestinal obstruction symptoms was more frequent in severe IND patients than in mild IND and FC patients (45.5% v 18.8% v 2.7%, respectively; P <.001). The presence of a fecaloma and soiling were less frequent in the severe IND group than in mild IND and FC groups (20.5% v 56.3% v 59.5%, respectively; P <.001 and 15.9% v 31.3% v 59.5%, respectively; P <.001). Barium enema results showed a lower incidence of rectosigmoid distension in severe IND if compared with mild IND and FC groups (45.5% v 57.1% v 96.9%; P <.001). Internal sphincter relaxation was absent frequently in the severe IND group compared with the FC group (47% v 26.9%, respectively; P <.05). CONCLUSIONS: Intestinal neuronal dysplasia is a distinct histopathologic and clinical entity. Its clinical, radiologic, and manometric presentation correlates to the severity of histochemical findings.

Comparación de la incisión limbar vs. incisión con flap escleral en la facoéresis EC con LIO / Comparison between limbar incision vs. scleral flap incision in in phakoeresis with IOL

En la facoéresis EC + LIO, uno de los aspectos que aún queda por resolver es el astigmatismo postquirúrgico, que no permite un resultado visual acorde al corto período de recuperación postop. En dos grupos, uno con flap escleral y uno con incisión corneal clásica, de 35 y 27 ojos, respectivamente, se estudió en forma prospectiva el astigmatismo corneal postquirúrgico. Aparte del tipo de incisión todas las variables se mantuvieron constantes durante y después de la cirugía y se realizó queratometría desde el primer día postop. hasta 1 año de seguimiento. Los resultados muestran una reducción significativa del astigmatismo desde las 2 semanas hasta el sexto mes postop., para luego disminuir paulatinamente hasta el año. Se analizan las ventajas del flap escleral, tanto para la rápida rehabilitación visual como para la cirugía

Estructura de la demanda de un servicio de urgencia en situación de catástrofe / Estructure of the demand of an emergency service in disasters situation

Se presentan las variaciones ocurridas en la estructura de la demanda del servicio de urgencia de un hospital general de la Región Metropolitana, en el día de ocurrencia y siguientes al sismo de marzo de 1985. En la comparación con igual período del año anterior 1984, se evidencian diferencias en los grupos de patologías en cuyo origen tiene influencia el stress, tales como son los trastornos neurofuncionales, el síndrome anginosos, la hemorragia digestiva alta y el asma bronquial, siendo estas diferencias estadísticamente significativas. A la inversa las patologías de consulta habitual en un servicio de urgencia, y cuya frecuencia o agravación no tienen relación con el stress, no experimentaron variación significativa a raíz del terremoto comparadas con su ocurrencia en fecha similar del año anterior. Se analizan también las variaciones de las patologías relacionadas al stress en términos de sexo y edad, destacándose el predominio de consultantes mujeres afectadas por trastornos neurofuncionales y neurológicos. Se señalan la importancia de la información obtenida en la administración de los recursos de atención de salud en situaciones de emergencia como la en referencia y la posibilidad de preparar equipos profesionales para afrontar las exigencias particulares de la demanda en casos de catástrofes