Parametric and kinetic study of washing pretreatment for K and Cl removal from rice husk

Rice husk is an abundant agricultural waste that can be used in combustion applications. The use of agricultural waste in combustion applications is hindered by slagging, fouling, and corrosion due to elements such as K, Cl, and Si. With the aim of removing those problematic elements using water washing, lab-scale experiments were conducted to study the effect of washing parameters; temperature, time, and liquid to solid ratio and to recommend suitable washing conditions. The washing temperature of 65 °C and liquid to solid ratio of 100 was selected as the best process conditions. Within 10 min of washing time, 75% of Cl and 50% of K can be removed. Pseudo-second-order kinetic model is suitable to describe the leaching behavior, and the kinetic parameters were obtained for the leaching of K and Cl. In industrial installations, hot condensate from process use of steam can be recommended as a good source of washing medium.