Production of biodiesel from an olive oil industry waste

MARIANA S. ALVEREZ; DEBORATH M. REINOSO; GABRIELA M. TONETTO

Buenos Aires

Conferencia; 2nd RCN Conference on Pan American Biofuels & Bioenergy Sustainability; 2016

With the growth of global energy demand andhigh levels of pollution, sustainable fuel alternatives have become a highpriority for many countries. Biodiesel is one of these sustainable fuelsobtained from vegetable oils or animal fats. Consists of alkyl esters derivedfrom either the transesterification of triglycerides or the esterification offree fatty acids with short-chained alcohols. Biodiesel comes with manyadvantages; low emissions of CO2 compared to petroleum diesel, biodegradable,non-toxic. Argentina is currently one of the majorbiodiesel producer worldwide, using soybean oil as raw material. In thecountry, the diesel must contain 10% biodiesel since 2014. Biofuel productionprograms have several social and environmental impacts and affected foodmarkets through diverting grain away from food for fuel. Therefore, utilizingbiomass residues for biodiesel production will reduce its contribution to foodprice. Also, the use of cheap low quality feed stocks will help in improvingthe economic feasibility of biodiesel.Biomass (such as agricultural residues, animalwastes, forestry and wood processing residues, municipal or industrial wastes)is seen as one of the most promising, renewable energy sources because it canbe converted to other usable forms of energy, like biofuels. It is relativelycheap energy resource to provide the initial feedstock in bioenergy industry.This would mean the elimination of a waste stream and gives biofuel producer achance to reduce costs.Alperujo is a waste product from the process ofolive oil extraction (two-phase extraction process). It is a blend made ofwater, oil, cellulose, lignin, proteins, carbohydrates, small portions ofactive phenol compounds and other derivatives. It is not environment-friendlyand it leads to serious ecological problems once alperujo is scattered on thesoil. It has a phototoxic activity that does not permit plants to germinate.Olive plantations in Argentina are rapidly expanding, therefore alperujo is awaste to the environment that needs to be treated.In the industry is used an alkaline homogeneouscatalyst. One of the main problems of these catalysts is the difficulty inusing low-cost raw material, such as the formation of soap due to theneutralization of free fatty acids present in low-quality oils, or thesaponification of triglycerides in the presence of water. The use of aheterogeneous catalyst would simplify the separation and purification steps.There is a growing interest in finding a solid catalyst that is active in thetransesterification of triglycerides, while it is selective with raw materialsof low quality, that is to say a catalyst that is stable in the presence of FFAand water. Given that it will be used in ?green? processes, it should also benon-pollutant and non-toxic. In this study, alperujo has been successfully usedas feedstock to obtain biodiesel using zinc stearate as a new clean catalystfor an environmentally-friendly biodiesel production. The catalyst was able tocatalyze simultaneously the triglyceride transesterification and the fatty acidesterification reactions with high activity and selectivity under moderateoperating conditions.