Effect of carbon black on chitosan‐poly(methacrylic acid) semi‐interpenetrating network hydrogels in swelling and dye adsorption

Abstract Semi‐interpenetrating network hydrogels were prepared by blending chitosan with methacrylic acid and carbon black. Chitosan is a linear polymer of randomly distributed d ‐glucosamine units and N ‐acetyl d ‐glucosamine units joined through 1,4‐β‐glycoside linkages. Methacrylic acid is 2‐methyl prop‐2‐enoioc acid. During the process, methacrylic acid was subjected to polymerization in the presence of potassium persulfate and crosslinked with N , N ′‐methylene bisacrylamide. The resultant hydrogels were characterized by DSC, TGA and Fourier transform IR. The gels were found to have good mechanical and thermal properties. Swelling studies were done under acidic, neutral and basic conditions and excellent results were obtained. The gel content was also calculated for all the gels and it was as high as 90%. Kinetics and diffusion of the gels were studied and the relevant parameters were calculated. The adsorption of the dyes methylene blue and malachite green by the gels from aqueous solution were studied photometrically and excellent results were obtained. It was found that the addition of carbon black greatly improved the adsorption of dyes from aqueous solution. The dye adsorption process was found to follow pseudo second order kinetics. © 2025 Society of Chemical Industry.