Application of polyacrylamide-based hydrogels for water removal from biodiesel in isothermal experiments

Abstract Fuels with water contents higher than the limits specified by regulatory agencies may be subjected to high turbidity, microbial growth fouling, sludge formation, and promote the corrosion and failure of fuel injection components. In this investigation, polyacrylamide, poly(acrylamide-co-sodium acrylate) and poly(acrylamide-co-acrylic acid) hydrogels were used to adsorb water from biodiesel in a batch system at 20 °C. The water content of biodiesel samples saturated with water could be lowered down to near 400 mg of water/kg of biodiesel under equilibrium conditions, a value comparable to other more mature technologies and in accordance with the EN 14214 standard. Among the three adsorption isotherm models fitted to the experimental data, the Freundlich model presented the best fit for polyacrylamide and poly(acrylamide-co-sodium acrylate) hydrogels, but all models failed for the poly(acrylamide-co-acrylic acid) hydrogel. The use of hydrogels for removal of water from fuels can be easily scaled up to a continuous process for commercial applications.