Synthesis, Microstructural Framework, and Swelling Kinetics of Chitosan-Graft-Poly(Acrylic Acid) Superabsorbent Hydrogels

International Journal of Chemistry | Vol. 9, No. 3, March 2018 | pp. 17–24

DOI: 10.46882/2018/IJC/000114

Article Type: Original Research Paper

Title: Synthesis, Microstructural Framework, and Swelling Kinetics of Chitosan-Graft-Poly(Acrylic Acid) Superabsorbent Hydrogels

Names of Authors: J. K. Mensah¹, S. K. Mukherjee²*

Authors’ Affiliations:
¹Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
²Department of Chemical Engineering, Indian Institute of Technology, Kharagpur, India.

Abstract: The development of durable biopolymeric hydrogel networks is essential for controlled agrochemical delivery and agricultural soil water retention due to the requirement for specific structural coordination sites. This study describes the chemical synthesis and rheological optimization of a hybrid hydrogel fabricated via the free-radical graft copolymerization of acrylic acid onto a high-viscosity seafood chitosan backbone. The grafting reaction was initiated using potassium persulfate (KPS) and crosslinked via N,N'-methylenebisacrylamide (MBA) under optimized atmospheric conditions. Structural networks and morphology features were characterized using FT-IR spectroscopy, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Swelling kinetics were evaluated as a function of time, pH, and saline concentration. The hydrogel showed highly responsive pH-dependent swelling profiles, achieving a maximum water absorption capacity of 430 g/g at pH 7.4 due to structural carboxylate ionizations causing intermolecular chain repulsions. Rheological analysis confirmed strong non-Newtonian shear-thinning characteristics with a storage modulus (G') that remained constant up to 80°C. Batch adsorption tests showed high affinity for divalent cadmium and lead ions, matching the Langmuir isotherm with monolayer capacities of 68.4 mg/g and 82.6 mg/g at 298 K, confirming high remediation potential.

Keywords: Chitosan; Acrylic acid; Graft copolymerization; Hydrogel; Swelling kinetics; Heavy metal adsorption

Manuscript Timeline: Received: November 15, 2016; Revised: December 22, 2016; Accepted: January 20, 2017; Published: March 04, 2018.

Citation: Mensah, J. K., & Mukherjee, S. K. (2018). Synthesis, Microstructural Framework, and Swelling Kinetics of Chitosan-Graft-Poly(Acrylic Acid) Superabsorbent Hydrogels. International Journal of Chemistry, 9(3), 17–24.

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