Synthesis and Characterization of Superabsorbent Polymer (SAP) from Cotton Waste Cellulose

A super absorbent polymer (SAP) is a class of polymers that absorb large quantities of water more than a typical absorbent material. Recently, research on the use of waste raw materials has extensively been studied. One particular waste material of interest is cotton waste, which is known to be a good source of cellulose. In this study, a sustainable SAP from carboxymethylcellulose sodium (CMC) and extracted cellulose from cotton waste material at varying weight ratios of CMC to cellulose (7:3, 2:1, and 5:5) crosslinked with citric acid was proposed. The produced SAP samples were then characterized by Scanning Electron Microscopy (SEM) for morphological properties and a Fourier Transform Infrared Spectroscopy (FTIR) analysis for the functional groups' identification. In addition, the swelling rate, absorptivity, and water retention were investigated to evaluate the performance of the prepared SAP. The SEM results showed that there is an increasing porosity of the surface of SAP as the concentration of CMC increases. FTIR results indicate that the cross-linking formation of the carboxylic group was visible at the band range from 1640 to 1600 cm^-1 and the presence of the OH^-1 bond was found at the band range from 3500 to 3000 cm^-1, which is essential in water absorption. For the swelling rate of the SAP samples, it took 45 to 50 minutes to reach swelling equilibrium while the maximum swelling capacity was found to be 68 and 55 g H₂O per g dry sample for the 7:3 and 2:1 ratio of CMC–cellulose solution samples. Water retention results showed that 13.8 and 15.9% of water was lost, respectively. The results of this study showed the potential of cotton waste as a sustainable source of cellulose for the production of SAP.