Biopolymer‐Enhanced PAAc / PAAm Hydrogels: Impact of Carrageenan Incorporation on Structure, Functionality, and Adsorption Behavior for Wastewater R

ABSTRACT

Poly(acrylic acid‐co‐acrylamide) (PAAc/PAAm) and carrageenan incorporated PAAc/PAAm (CAR/PAAc/PAAm) hydrogels were synthesized via free‐radical polymerization using sodium persulfate as a chemical initiator. The effect of carrageenan incorporation on the structural, thermal, swelling, and adsorption properties of the hydrogels was systematically investigated. FTIR and XRD analyses confirmed successful network formation and increased amorphous character after carrageenan addition, while TGA demonstrated improved thermal stability. SEM, AFM, and EDX analyses revealed a rougher, more porous surface enriched with sulfate functional groups, providing enhanced adsorption sites. The CAR/PAAc/PAAm hydrogel exhibited higher swelling capacity and pH‐responsive behavior compared with pristine PAAc/PAAm. Adsorption studies using methylene blue (MB) and tartrazine yellow (TY) dyes showed significantly higher removal efficiency and faster adsorption kinetics for the carrageenan‐modified hydrogel. Kinetic and isotherm analyses indicated diffusion‐controlled adsorption for TY and chemisorption‐dominated adsorption for MB, confirming the strong role of carrageenan in enhancing dye uptake. These results demonstrate the potential of CAR/PAAc/PAAm hydrogels as efficient and sustainable adsorbents for wastewater treatment.