Acrylamide and Acrylate Based Hydrogel for Water Adsorption in Biodiesel

Abstract

Several countries have implemented the use of biodiesel as a diesel fuel blend. Indonesia currently implements the highest percentage of biodiesel, reaching 30% (B30), starting from 2020. Strict quality standards of biodiesel have been implemented worldwide, such as ASTM D6751 (USA), EN 14214 (EU), JASO M360 (Japan), and SNI 7182:2015 (Indonesia). Prior to blending with diesel, biodiesel must comply with the specification. One of the most concerning issues is the water content in biodiesel that is easily increased due to its hygroscopic nature. Currently, the handling procedure at the blending facility to maintain the immoderate water content of biodiesel is still limited. Therefore, experiments for reducing excessive water content in biodiesel were conducted using polyacrylamide-co-potassium acrylate (pAAm-co-PA) and potassium polyacrylate (PPA) hydrogels with varying contact times. The adsorption capacity of the hydrogel with the best performance was also observed. Four methods were carried out for hydrogel regeneration, i.e., drying at atmospheric pressure (A), drying at vacuum pressure (V), and a combination of solvent washing-atmospheric drying using acetone (AA) and ethanol (EA). The results indicate that the PPA hydrogel adsorps more water than the pAAm-co-PA hydrogel with the same contact time. PPA hydrogel capacity decreased to 13.4% after being used for seven adsorption cycles simultaneously. The ethanol-drying combination produces the highest water recovery in the regeneration process, reaching 39.24%.