Showing papers in "Canadian Journal of Chemical Engineering in 2006"

Kinetics of Silica Dissolution from Rice Husk Char

Abstract: The effect of leaching time and temperature on the ash content of rice husk char and the resultant surface area development was investigated. Experiments on dissolution of rice husk char ash with 0.5 mol NaOH solution were conducted at 40°C, 60°C, 80°C and 95°C for different times up to 7200 s. The surface areas of the leached chars after drying were determined using Micromeritics 2200 surface area analyzer. The leaching data was analyzed using different models applicable for fluid-solid non-catalytic reactions. It was found that the data could be satisfactorily represented by diffusion-controlled mechanism as well as modified shrinking core models. The activation energies were in the range of 41.75 to 51.25 kJ/mole. The surface areas of the leached chars were found to depend linearly on the percentage of ash content in the chars. On a etudie l'effet du temps de lessivage et de la temperature sur la teneur en cendres de cosses de riz carbonisees et le developpement de surface qui en resulte. Des experiences ont ete menees sur la dissolution des cendres de cosses de riz avec une solution de NaOH de 0,5 mole a 40 oC, 60 oC, 80 oC et 95 oC pour differents temps allant jusqu'a 7200 sec. Les aires de surfaces des cendres apres le sechage ont ete determinees a l'aide d'un analyseur de surface 2200 de Micromeritics. Les donnees de lessivage ont ete analysees a l'aide de differents modeles applicables a des reactions fluide-solide non catalytiques. On a trouve que les donnees pouvaient etre representees de maniere satisfaisante par le mecanisme controle par la diffusion et par les modeles de noyau retrecissant modifies. Les energies d'activation sont comprises entre 41,75 et 51,25 kJ/mole. On a trouve que les aires de surfaces des cendres lessivees dependaient lineairement du pourcentage de teneur en cendres dans les produits carbonises.