Cellulose hydrogels for water removal from diesel and biodiesel: Production, characterization, and efficacy testing

Abstract

Using hydrogels for water removal from fuels is a novel process that has shown promising results. So far, only synthetic hydrogels have been used for this purpose. This article presents the results of innovative research that applies cellulose hydrogels to remove water from diesel and biodiesel. Different methods for hydrogel preparation (addressing proportions of cellulose from 4 to 6 wt% and of epichlorohydrin from 5 to 10 vol%), crosslinking induction (in a conventional oven, microwave, and thermostatic water bath), and hydrogel drying (oven- or freeze-drying) were analyzed. The materials obtained were characterized by FTIR, SEM, XRD, and also regarding compressive strength. The swelling degree and the percentage of water removal from diesel and biodiesel were investigated with a 23 factorial design. The best performance was achieved with the hydrogel synthesized with 4 wt% cellulose and 10 vol% epichlorohydrin, with crosslinking induction at 60 °C in a conventional oven for 4 h. The freeze-drying process generated a porous structure with a higher swelling degree (up to 22 g.g−1). However, no significant differences were observed in water removal using freeze- or oven-dried hydrogels. The exposure of the fuels to the hydrogels allowed the removal of 34–62% of the water from biodiesel and 70–82% from diesel. The pseudo-second-order model satisfactorily fitted the data of water removal kinetics, and equilibrium conditions were reached after 12 h. Thus, this research opens the possibility of using an innovative process and a sustainable biomaterial for fuel treatment.