Okara is a fiber rich waste from soybean industry that can be a potential material to make hydrogel. In this study, okara cellulose based hydrogel with high water swelling was fabricated. First, cellulose was extracted from okara using alkaline treatment of 5% (w/v) NaOH solution. The okara cellulose was crosslinked with polyvinyl alcohol (PVA) forming hydrogel using glutaraldehyde as the crosslinking agent. However, the PVA/okara hydrogel had a low water swelling of 19 g/g. Alternatively, another method using carboxymethyl cellulose (CMC) was attempted due to its high hydrophilicity. CMC and okara cellulose were crosslinked by epichlorohydrin as the crosslinking agent. The water swelling of CMC/okara hydrogel reached 390 g/g which is higher than the previous studies of okara hydrogels....[ Read more ]

Okara is a fiber rich waste from soybean industry that can be a potential material to make hydrogel. In this study, okara cellulose based hydrogel with high water swelling was fabricated. First, cellulose was extracted from okara using alkaline treatment of 5% (w/v) NaOH solution. The okara cellulose was crosslinked with polyvinyl alcohol (PVA) forming hydrogel using glutaraldehyde as the crosslinking agent. However, the PVA/okara hydrogel had a low water swelling of 19 g/g. Alternatively, another method using carboxymethyl cellulose (CMC) was attempted due to its high hydrophilicity. CMC and okara cellulose were crosslinked by epichlorohydrin as the crosslinking agent. The water swelling of CMC/okara hydrogel reached 390 g/g which is higher than the previous studies of okara hydrogels. The swelling increased with more swelling cycles and remained effective until the fifth cycle. In KNO₃ and NH₄NO₃ solutions (0.05 ⎯ 0.1M), the swelling was significantly reduced by 75-85%. The hydrogel was characterized by scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). With high swelling ability, the CMC/okara hydrogel can be applied as a soil conditioner to retain water near the roots in dry areas.