Casca de arroz como agente adsorvente no tratamento de óleo residual

Abstract

The development of technologies that reuse wastes from the agricultural, industrial and urban activities is essential, mainly at the environmental point of view, since high amounts of toxic materials and pollutants are incorrectly disposed on the environment, practice that tends to grow concurrently with the industrial expansion. The waste cooking oil is generated in large volumes in urban centers due to the high consumption of refined oils in food cooking. This is considered as a potential alternative feedstock for biodiesel synthesis, one of the country’s mainly used biofuels. However, the low and inconstant quality of this residual feedstock is one of the barriers for its use at homogeneous alkaline transesterification, route commonly used in the biodiesel production thus requiring pretreatment steps of the waste cooking oil before this process. In this context, the objective of this work was the treatment of waste cooking oil by adsorption process, using the in natura rice husk, biomass from agricultural sector, and actived carbon as adsorbent materials. From an experimental planning of the rotational central composite design, it was searched the best experimental conditions for the waste cooking oil treatment in relation to the temperature, adsorbent mass and agitation speed, thus evaluating the influence of these operational parameters on the reduction of the acidity value and peroxide value, and aiming the simultaneous maximization of analyzed variables at the intervals tested. Using the activated carbon (commercial adsorbent) average reductions of acidity and peroxides of 47 and 29 %, respectively. Observed using the rice husk, the reductions was 40 and 24 % for acidity and peroxides, respectively. In order to minimize process costs, in addition to the use of residual materials, the use of rice husk as an alternative adsorbent in the residual treatment is advantageous, since it is a low cost material, available on a large scale and gave results close to those obtained with the activated carbon.