Avaliação do uso de óleo residual de algodão na produção de biodiesel

Abstract

In biofuels production, residual oils consists in low-cost raw material that comply economic and environmental viability. Even though it is considered a byproduct, the oil extracted from cottonseed has become the third most used source in Brazilian biodiesel industries, only behind soybean oil and beef tallow. This study evaluated the conditions of ethyl esters synthesis by chemical catalysis via methyl route, with NaOH as catalyst, using cottonseed oil from frying processes. The transesterification reactions were carried out in a reactor under indirect heating and constant stirring for one hour, with residual oil, alcohol and catalyst as reaction medium. The ester conversion results for the three experiments performed were 97.56%, 97.04% and 97.30%. The parameters of free glycerol, total glycerol, monoacylglycerol, diacylglycerol and triacylglycerol was defined in accordance with ANP’s 45/2014 regulations. However, the acidity index for the biodiesel samples showed high values that do not fit within the limits of the ANP's regulations. The variation on this parameter may indicate traces of oxidation of cottonseed oil due to the deep frying process. However, further studies of the residue are needed to elucidate this results.