Polymer hydrogel for water removal from naphthenic insulating oil and marine diesel

[Display omitted] •An extensive physicochemical characterization of the oils was carried out.•Water solubility curves as a function of temperature were determined.•Acrylamide-based hydrogels were synthesized and applied to oil drying.•Deep water removal was reached with decrease in the oil turbidity.•Hydrogels can be regenerated and reused. The control of water content in industrial oils and fuels is a key factor to avoid degradation during the storage period and guarantee their expected performance. Thus, our work investigated the application of polymer hydrogel to remove water from naphthenic insulating oil (NIO) and marine diesel oil (MDO). Two acrylamide-based hydrogels were synthesized by free radical polymerization: poly(acrylamide-co-sodium acrylate) and poly(acrylamide-co-acrylonitrile). Prior to batch tests for water removal, the hydrogels were characterized by SEM, pore size distribution, DVS, FTIR, and XDR. An extensive physicochemical characterization of MDO and NIO was performed, including the determination of water solubility curves. A 22 factorial design with duplicates was carried out to examine the effects of the hydrogel mass and hydrogel type on the water content in the oils. Finally, kinetic and thermodynamic studies of the water removal process were carried out. In just 60 min, the hydrogel removed approximately 80% of water from NIO and MDO, considering 1 g of hydrogel and 50 mL of emulsion at 25 °C. The two lowest temperatures studied (25 °C and 35 °C) showed the best hydrogel performance. Tests of hydrogel reuse showed the polymer can be regenerated without losing its water removal capacity.