Synthesis of a Novel Cellulose Nanofiber-Based Composite Hydrogel with Poly(methyl methacrylate-co-methacrylic Acid) for Effective Water Removal from Liquid Fuels

Water is present in liquid fuels in three different forms: dissolved, free, or emulsified, and its presence can considerably impair fuel quality by encouraging microorganism growth. This growth contributes to the generation of sludge, an increase in turbidity, and the corrosion of tanks and mechanical components of motor vehicles. In this context, this research work proposes the synthesis of a nanocomposite hydrogel made of poly(methyl methacrylate-co-methacrylic acid) and cellulose nanofibers (CNFs) by free radical polymerization for removal of water from diesel. An extensive physicochemical characterization of the hydrogels was performed, and a full experimental design (2² with 3 central points) evaluated the influence of the different CNF percentages and temperatures on the maximum swelling degree of the hydrogel nanocomposites. According to this experimental design, the only statistically significant independent variable was the CNF percentage. Finally, batch tests were performed to build the kinetic curves based on five adsorbents: CNF, poly(MMA-co-MAA), and poly[(MMA-co-MAA) with CNF at 1, 2.5, and 5%]. All samples were highly effective at removing water from commercial diesel in a short time. In this analysis, CNF reached equilibrium in 3 h, while all other samples required 8 h. All composite hydrogels exceeded 80% water removal at the equilibrium time. The high efficiency of the nanocomposites was demonstrated, suggesting the potential for application on an industrial scale, over a wide range of water concentrations.