Rice Husk Char/Poly-(Acrylic Acid-co-acrylamide) Superabsorbent Hydrogels: Preparation, Characterization, and Swelling Behaviors

Abstract

A series of novel rice husk char/poly-(acrylic acid(AA)-co-acrylamide(AM)) superabsorbent hydrogels were synthesized by graft copolymerization. The effects of the rice husk char (RHC) loading on their miscibility, shapes, and chemical structures were studied, and their swelling behaviors, kinetics, and pH response were evaluated. During the preparation, RHC reacted with acrylic acid. The RHC at lower loads (< mass ratios of RHC and AA of 1%) was scattered well within the polymer matrix, but an excessive load might result in the formation of large agglomerates. The swelling capacity and swelling rate of the hydrogels first were both increased with the rising RHC loading to 1% and then declined with further RHC loading. The superabsorbent hydrogel containing 1% RHC had the highest water absorbency (869 g/g in deionized water and 97 g/g in 0.9% NaCl solution).

Magnetic Nanoparticles-Grafted-Poly (Acrylic Acid) as a Super-Hydrogel Composite: Preparation, Characterization and Application in Agriculture

“…Swelling ratio analysis: The swelling ratio was measured according to Pan et al 30 . Briefly, a dry synthesized hydrogel (1 g) was soaked in 500 mL of deionized water at room temperature for 4 hrs until reaching the swelling equilibrium.…”