Synthesis and characterization of zein-based cryogels and their potential as diesel fuel absorbent

In this study, zein-protein based cryogels were synthesized by solution-based graft copolymerization of acrylic acid monomers onto zein protein backbones in the presence of an acrylamide crosslinker and initiators (sodium bisulfite and potassium persulfate). The grafting was confirmed by Fourier transform infrared spectroscopy. The thermal properties of the cryogels were assessed by thermogravimetric analysis and their morphology was studied by scanning electron microscopy and Brunauer–Emmett–Teller surface analysis. It was found that freezing the materials using liquid nitrogen at −196 °C before drying increased the surface area of the cryogels as compared to freezing at −20 °C. Dynamic mechanical analysis tests revealed that cryogels with increased acrylic acid content captured ambient moisture more quickly. The absorption capacity tests were performed in water and in diesel fuel. The highest equilibrium swelling of cryogels in distilled water reached 119.5 g/g of cryogel after 1 h while the highest equilibrium swelling in diesel fuel reached 49.8 g/g of cryogel in 15 min.