This work aims to fabricate a new sustainable water-absorbent hydrogel (WAH) using microwave irradiation technique to enhance time efficiency, cost-effectiveness and environmental friendliness, along with indigenous agricultural rice husk (RH) to achieve both absorbance and sustainability.
Five levels of grafted poly(MAA)-rice husk graft copolymers (PMAARHGC-I to PMAARHGC-V) with varying graft yields were synthesized using methylene-bis-acrylamide as a crosslinker. Characterization techniques such as Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), zeta potential and Brunauer–Emmett–Teller (BET) analysis were used. The WAHs were developed to address water and saline absorption challenges by investigating factors like hydrogel dose, absorption rate, pH, grafting extent and crosslinking to optimize economic treatment conditions. A mechanism for hydrogel formation was also proposed.
Based on the achieved outcomes, optimum conditions were established for grafting carboxyl functional groups onto RH using 50 m mole/l potassium persulphate, 100% MAA concentration and 10 m mole/l methylene-bis-acrylamide. Validation techniques included FTIR confirming a band at 1,677 cm−1, SEM displaying a porous structure, XRD indicating low crystallinity and a zeta potential peak at −34.4 mV. Maximum water and saline absorbency were 79.7 g water/g polymer and 39.8 g saline solution/g polymer, achieved with 1.0 g of hydrogel, 35.2% graft yield, 10 m mole/l N,N′- methylene bis acrylamide and pH 7 over 60 min.
The innovation considered here involves the development of a new sustainable WAH, which was engineered using eco-friendly methods, including microwave processing and incinerated RH bio-waste.
