Synthesis, characterization and water-absorption behavior of tartaric acid-modified cellulose gel fromcorn stalk pith

The eco-benign water-absorbent gel was obtained by modification of tartaric acid (TA) onto parenchyma cellulose from corn stalk pith (CSP) in N, N-dimethylacetamide (DMAc)/LiCl system. The water affinity of the gel was aided with TA as both grafting agent and cross-linker via esterification. The degree of swelling was strongly influenced by TA amount, reaction temperature and duration, and the absorbency of TA-esterified product reached up to about 417 g H2O/g dry gel. The three-dimensional macro-porous structures of the bio-absorbent led to fast penetration and diffusion of water into gel. Studies of absorption behavior in deionized water showed that the initial water uptake followed the non-Fickian mechanism, the Schott second-order equation governed the swelling kinetics, and the later part of swelling was relaxation of polymer chains. FTIR and X-ray diffraction analyses confirmed successful modification of TA molecules onto cellulose chains through the formation of ester bonds and transition of crystalline forms from cellulose Ⅰ to cellulose Ⅱ. Moreover, thermogravimetric outcomes illustrated the thermal resistance of the TA-esterified gel with a loose structure was lower than SCP cellulose. This work designed a green water-absorbent that could be potentially utilized as favorable water retention material in agriculture and horticulture.