Experimental planning applied to the synthesis of superabsorbent polymer by acrylic acid graft in pectin extracted from passion fruit peel

Abstract

Superabsorbent hydrogels are three-dimensional matrices made up of linear or branched hydrophilic polymers, have chemical or physical crosslinking, and can absorb large amounts of water. Herein we used experimental planning to optimize the synthesis of superabsorbent polymers from pectin extracted from passion fruit peel, grafted with polyacrylic acid and crosslinked with N,N′-methylene-bis-acrylamide. The chemical structures of the polymers were analyzed by infrared and Raman spectroscopy. The spectra obtained prove the polymerization reaction, the graft and the absence of residual monomers. The experimental planning allowed the establishment of the optimum synthesis conditions for the best water absorption and urea and Cu2+ adsorption properties. For this purpose, we used the degree of monomer neutralization and the percentages of pectin, crosslinking agent, and initiator, as variables. The kinetic studies for Cu2+ adsorption showed that the predominant mechanism was pseudo-second order. Finally, atomic force microscopy showed the topography of the materials and the presence of cavities only in the sample with the best urea-adsorption capacity.