Double network hydrogel of sodium alginate/polyacrylamide cross-linked with POSS: Swelling, dye removal and mechanical properties

In this work, for the first time, we presented a novel design strategy to fabricate a new type of Octa-aminopropyl polyhedral oligomeric silsesquioxane hydrochloride salt (OA-POSS)-based Alg/PAAm DN gels, consisting of PAAm gel as the first chemical network and Alg/OA-POSS gel as the second chemical-physical network. Incorporation of OA-POSS nanoparticles with various feed ratio into the second network not only led to form strong coordination interactions but also in comparison to the other Alg/PAAm gels demonstrated superior mechanical properties. pH, temperature, contact time and salt effects parameters were studied on the swelling and dye removal properties of the synthesized DN hybrid hydrogels. The adsorption experiments exhibited that 20 mg of Alg/PAAm/OA-POSS1 showed the maximum adsorption capacity for methylene blue (MB) at pH 9 and 11. Dye adsorption kinetics were modeled by the pseudo-first-order, pseudo-second-order and intra-particle diffusion kinetic equations under different conditions. Additionally, adsorption isotherms of the adsorption of MB were analyzed.