Preparation of Carboxymethyl Cellulose Superabsorbents from Waste Textiles

Production of superabsorbent polymers from cotton and viscose waste textiles was investigated. The cellulose wastes were carboxymethylated, crosslinked by divinylsulfone, and then converted to superabsorbent material using air-drying, freeze-drying, or air-drying after phase inversion. The separation of cellulose from synthetic polymers in the textile (polyester) was carried out by direct dissolution of cellulose in N-methylmorpholine-N-oxide (NMMO), or separation by dissolution in water after carboxymethylation of the textiles. The progress of the carboxymethylation reaction was evaluated by measurement of the degree of substitution (DS) of carboxymethyl cellulose (CMC). The DS values of 0.50-0.86 confirmed the prosperous substitution of hydrophilic carboxymethyl groups into the cellulosic chains. The water binding capacity and the swelling rate of the superabsorbents prepared under different conditions were measured. Under the best condition the superabsorbent obtained from waste textiles showed an ultimate water binding capacity of 541 g/g which was notably higher than that of the reference superabsorbent derived from cotton linter (470 g/g). The amount of absorbed water by this product exceeded that of the reference sample after 60 min immersion.