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The ester product of the vegetable oil−alcohol transesterification reaction (biodiesel) is the best and the most popular diesel fuel alternative. The refining of the transesterification reaction products is technically difficult and brings an extra cost. Also, the purity level of the biodiesel must conform to European Union standards for alternative diesel fuels. The target of this study was to investigate the refining of the product mixture obtained by the transesterification reaction (with an alkali catalyst) of neutralized rapeseed oil (extracted from the seeds of the rape plant cultivated in the Thrace region of Turkey) with methanol. To obtain pure biodiesel conformable to the standards, methods of washing with hot distilled water, dissolving in petroleum ether and then washing with distilled water, and neutralization with H2SO4 (1:1) were tested in the refining step. Washing with hot distilled water at 50 °C was chosen as the best refining process. The purity of the biodiesel obtained was about 99%.

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The concept of a biorefinery that provides valuable bioproducts from biomass conversion instead of fossil based products is presented. One of the main biorefinery products, bioethanol, can be produced from sugar, starch, or lignocellulosic-based biomass. Lignocellulosic-based bioethanol could be a good alternative to sugar- or starch-based bioethanol. While sugar- and starch-based biomass includes mainly glucose or starch, lignocellulosic biomass contains cellulose, hemicellulose, and lignin. While the cellulose is essential for the biomass-to-bioethanol conversion process, hemicellulose and lignin are undesirable in this context, and therefore pretreatment is necessary to break down the lignocellulose structure and separate hemicellulose and lignin from cellulose. Organosolv pretreatment is an attractive method for separating both cellulose and nearly pure lignin from the lignocellulosic material. In a biorefinery, organosolv pretreatment is one of the best options for producing more than one valuable product (bioethanol and lignin) in the same process. For effective bioethanol production, the delignification rate and enzymatic glucose conversion are fundamental parameters. This paper presents a detailed literature review of organosolv pretreatment, focusing on the effects of each of the pretreatment conditions for biorefinery applications. The organosolv pretreatment method is first described in detail and then each of the pretreatment conditions is explored individually. A number of technical studies are reviewed, and the effects of the various conditions on the delignification rate and on enzymatic glucose conversion for effective bioethanol production are described. The current status of development of organosolv-based biorefineries around the world is discussed. In previous reviews of this topic, only the solvent and catalyst effects have been investigated. This review will contribute to the literature by showing the impacts of all pretreatment conditions on pretreatment efficiency.

Biodiesel is one of the environmentally friendly alternative liquid biofuels that has proven itself commercially, with international standards all around the world. Industrial and scientific studies on reducing biodiesel production costs are one of the major contributions that have strengthened the position of biodiesel commercially. The type of vegetable oil used for biodiesel production is the parameter that has the greatest effect on biodiesel production cost. For this reason, investigations on the types of no-to-low-cost vegetable oils become crucial. In this study, the optimum conditions for biodiesel production from restaurant-originated used cooking oil (which is composed primarily of oleic and linoleic acids) and the refining procedure were investigated. A refining method of "washing with hot water" was used for biodiesel refinement. One of the properties of biodiesel that has an influence on biodiesel purity is glycerin content. In the refining studies, the effects of glycerin amount, used washing water amount, and the number of washing steps were discussed and biodiesel that meets EN 14214 standards was produced.