Production of high water-absorbing resin through irradiation-catalyzed graft copolymerization of mung bean straw cellulose: synthesis and characterization

Abstract

To procure environmentally – friendly and sustainable super-absorbent polymers (SAP), a concurrent irradiation approach utilizing ⁶⁰ Co γ-rays is employed to graft acrylic acid (AA) and acrylamide (AM) onto mung bean straw cellulose (MBS-cellulose). Using different solvents to dissolve the straw yielded a more soluble form. The structural characteristics and thermal stability of MBS-cellulose and the graft copolymer are also comprehensively analyzed. The influence of the MBS pre-treatment method, irradiation dose, irradiation rate, cross-linking agent dosage, monomer ratio, and MBS-cellulose proportion on the water absorption capacity and salt resistance of the graft copolymer is investigated. The research indicates that under specific synthesis conditions, the optimal reaction conditions for graft copolymerization were determined via single-factor experiments. The monomer ratio, specifically m (AA):m (Am), was set at 1.4. The material ratio, defined as m (AA + AM):m (MBS-cellulose), was 11. The neutralization degree of the monomer approximated 90 %. The irradiation dose was 6 kGy, the dose rate was 1.4 kGy/h, and the cross-linker dosage was 2.4 %. The resultant MBS-cellulose grafted copolymer exhibited a water absorption capacity of 2,340 g/g and a brine absorption capacity of 211 g/g.