Biodiesel dry purification with sugarcane bagasse

Biodiesel is an important renewable fuel that can be used as a substitute of petro diesel. Downstream processes represent a major concern in biodiesel production due to cost and because it is time consuming. The application of dry purification processes emerges as a promising alternative for biodiesel purification, but the applied adsorbent material should ensure biodiesel quality and process efficiency. Here we propose the application of sugarcane bagasse as a low cost adsorbent material for biodiesel treatment. Sugarcane bagasse was used in three different forms: raw sugarcane bagasse (as received), steam explosion pre-treated bagasse and bagasse ash. Equilibrium adsorption data showed that the addition of only 0.5 wt% of sugarcane bagasse removed 40% of the glycerine of the crude biodiesel and produced a purified biodiesel with less than 0.02 wt% of glycerine. The adjustment of equilibrium data to isotherm models showed that glycerine adsorption on sugarcane bagasse is not fully Langmuirian due to the heterogeneous surface of the adsorbent and the non-uniform distribution of heat of adsorption. Sugarcane bagasse proves to be a promising adsorbent for glycerine, with the maximum predicted glycerine adsorption of 88.86 mg g(-1). The kinetic data of glycerine adsorption in raw sugarcane bagasse could be adjusted to the pseudo-second order model, which indicates that the rate-limiting step may be chemisorption. Kinetic data highlighted the fast nature of the process, since the glycerine removal was greater than 70% after only 10 min of adsorption process. Sugarcane bagasse presented results for biodiesel purification similar to those for the wet washing process or with Magnesol. Thus, dry purification with sugarcane bagasse is a suitable alternative for biodiesel treatment in a low cost and efficient process. (C) 2016 Elsevier B.V. All rights reserved.