Different techniques for the production of biodiesel from waste vegetable oil

Abstract

ABSTRACT:The production of biodiesel from waste vegetable oil offers a triple-facet solution: economic, environmental and waste management. The new process technologies developed during the last years made it possible to produce biodiesel from recycled frying oils comparable in quality to that of virgin vegetable oil biodiesel with an added attractive advantage of being lower in price. Thus, biodiesel produced from recycled frying oils has the same possibilities to be utilized. While transesterification is well-established and becoming increasingly important, there remains considerable inefficiencies in existing transesterification processes. There is an imperative need to improve the existing biodiesel production methods from both economic and environmental viewpoints and to investigate alternative and innovative production processes. This study highlights the main changes occurring in the oil during frying in order to identify the characteristics of oil after frying and the anticipated effects of the products formed in the frying process on biodiesel quality and attempts to review the different techniques used in the production of biodiesel from recycled oils, stressing the advantages and limitations of each technique and the optimization conditions for each process. The emerging technologies which can be utilized in this field are also investigated. The quality of biodiesel produced from waste vegetable oil in previous studies is also reviewed and the performance of engines fueled with this biodiesel and the characteristics of the exhaust emissions resulting from it are highlighted. The overarching goal is to stimulate further activities in the field.

Biodiesel production from three mixes of oils with high free fatty content: quality evaluation and variable analysis

“…This indicated that the reaction had reached the saturation point and tended to favor the formation of gels that hinder the recovery of glycerol and decrease biodiesel yield (Encinar et al 2005). These results corresponded to those reported by Refaat, (2010) from which the best performance is obtained within a range of 0.5-1 %.…”

“…This technique requires precision and an adequate fatty acid profile of the oil sample (Table 3), for both, an excess as an insufficiency in the amount of catalyst added results in the formation of soaps (Refaat 2010). Considering that there is a direct relation between the FFA percentage and the amount of catalyst that has to be added to the reaction to compensate the acidity and its deactivation (Freedman et al 1986), alkaline neutralization was considered for the three samples as pre-treatment method for its effectiveness in lowering the FFA content, along with substantial quantities of mucilaginous substances, phospholipids and color pigments (Bhosle and Subramanian 2005;Sudhir et al 2007).…”

“…Two homogeneous alkaline catalysts, sodium hydroxide (NaOH) and potassium hydroxide (KOH), were tested considering that are the most widely used in transesterification for its low cost, high catalytic activity and ease in their operating and storage conditions (Refaat 2010). As stated earlier, a primary screening with both catalysts was performed, obtaining the best results with KOH (Tomasevic andSiler-Marinkovic 2003, Encinar et al 2007;Demirbas 2009).…”

“…By using WCO as feedstock, the presence of water in the samples was expected due to handling processes, and knowing that the water in the WCO accelerates the hydrolysis and simultaneously reduces the formation of esters (Arun et al 2011), it is vital a filtering and heating process in order to ensure an anhydrous medium which allows us to avoid the negative effects of the compounds formed during frying (Refaat 2010). The water content was determined for all the biodiesel samples within the normal limits.…”

Biodiesel Glycerides from the Soybean Ethylic Route Incomplete Conversion on the Diesel Engines Combustion Process

“…Instead, in ethanolysis, they are more stable and severe, making it tough to separate and purify the esters. 33 In this context, this study evaluates the effect of soybean biodiesel produced via base catalysis and via the methanol and ethanol routes (hereinafter referred to as MR and ER, respectively) on the performance and emissions of formulations containing 10 and 20% (m/m) of biodiesel, using base diesel with low sulfur content and CN of 45 and 50. The soybean biodiesel composition produced via MR and ER was analyzed by gas chromatography with flame ionization detector (GC-FID) and by mass spectrometry.…”