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Natural fibers from macadamia nut shell, dried coconut shell endocarp, unripe coconut mesocarp, sugarcane bagasse and pine wood residue were used to prepare activated carbon fibers (ACF) with potential application for removing microcystins. The ACF from pine wood and sugar cane bagasse were used to remove [D-Leucine¹]MCYST-LR from water. After 10 minutes of contact time, more than 98% of toxin was removed by the ACF. The microcystin adsorption monolayer, q m, in the ACF recovered 200 and 161 µg.mg-1, with the Langmuir adsorption constant, K L, of 2.33 and 1.23 L.mg-1. Adsorption of [D-Leucine¹]MCYST-LR in continuous process was studied for a fixed-bed ACF prepared from coconut shell and sugar cane bagasse and for two commercial activated carbon samples from treatment water plants of two Brazilian hemodialysis centers. Saturation of the beds occurred after 80 to 320 minutes, and the adsorption capacity for that toxin varied from 4.11 to 12.82 µg.mg-1

Jute fiber is the second most common natural cellulose fiber worldwide, especially in recent years, due to its excellent physical, chemical and structural properties. The objective of this paper was to investigate: the thermal degradation of in natura jute fiber, and the production and characterization of the generated activated carbon. The production consisted of carbonization of the jute fiber and activation with steam. During the activation step the amorphous carbon produced in the initial carbonization step reacted with oxidizing gas, forming new pores and opening closed pores, which enhanced the adsorptive capacity of the activated carbon. N 2 gas adsorption at 77K was used in order to evaluate the effect of the carbonization and activation steps. The results of the adsorption indicate the possibility of producing a porous material with a combination of microporous and mesoporous structure, depending on the parameters used in the processes, with resulting specific surface area around 470 m 2 .g -1 . The thermal analysis indicates that above 600°C there is no significant mass loss.

La acción de la energía de las microondas, genera porosidad interna en un material cerámico húmedo. En el presente trabajo, se analiza el efecto del tiempo de aplicación de las microondas sobre el comportamiento térmico, cambio de volumen, tamaño y distribución de poros, reacciones químicas y disolución de probetas cerámicas de silicato de sodio / ortofosfato cál-cico dibásico (FCD). Para caracterizar las espumas cerámicas, se utilizó, análisis de imágenes, microscopía electrónica de barrido, difracción de rayos X y picnometría de helio. Se obtuvieron espumas cerámicas con una porosidad de 71 a 79 % y un rango de tamaño de poro de 10 a 200 µm. Después de 90 segundos, las probetas alcanzaron una temperatura de aproximadamente 130°C y una pérdida de peso de 23% con respecto al peso total de la muestra. Se observaron cambios de volumen y de los compuestos químicos en las muestras espumadas cuando se varió la proporción del FCD en la mezcla. Para contenidos de 10, 20 y 30% en peso de FCD, el incremento de volumen se redujo a 350, 300 y 250% respectivamente. En muestras con 30% de FCD calentadas por microondas durante 90 segundos la cantidad de un nuevo compuesto en la espuma, constituido por β-NaCaPO 4 , fue del orden de 42.9%. En esa misma muestra, el 57.1 % restante fue FCD. Considerando pruebas de disolución de un gramo de muestra en 100 ml de agua destilada, la disolución obtenida en muestras espumadas por microondas después de 20 días fue de 900 ppm/gr para el Na y de 2.7 ppm/gr para el Ca en muestras con 10% de FCD. En muestras con 30% de FCD la disolución de Na fue de 470 ppm/gr y del Ca de 5 ppm/gr. Palabras clave: Espumas cerámicas, microondas, silicato de sodio, fosfato de calcio. Microwave foaming of sodium silicate-ortodibasic calcium phosphate mixturesThe effect of microwave application on the thermal behaviour, volume change, size and pore size distribution as well as chemical reactions and dissolution of sodium silicate/dibasic calcium phosphate ceramic (DCF) samples have been analysed. Ceramics foams with porosities between 71 and 79 wt% and pore sizes ranging from 10 to 200 microns have been obtained. After 90 seconds the temperature of samples reach about 130 °C with a weight loss of 23 wt%. Differences in the proportion of DCF in the initial mixture originate changes in volume and different chemical compounds in the final obtained foams. Additions of 10, 20 and 30 wt% of DCF originates volume increases of 350, 300 and 250 % respectively. In foam samples with 30 wt% of DCF, heated by microwave during 90 sec., the amount of the new compound β-NaCaPO 4 was about 42.9 wt%. The other component of this sample, 57.1 wt%, was DCF. Dissolution tests were made, using one gram of sample, in 100 ml of distilled water. The dissolution of 10 wt% DCF foamed samples, after 20 days into water, were 900 ppm/gr of Na and 2.7 ppm/gr of Ca. In samples with 30 wt% of DCF the dissolution were 470 ppm/gr and 5 ppm/gr for Na and Ca respectively. -INTRODUCCIÓNPor su estructura, existen básicamente dos categorías de espuma...