Water Absorption and Physicochemical Characterization of Novel Zeolite-PMAA-co-PAAm Nanocomposites

Abstract

The growth in global population has caused an increase in the demand for food production, leading to an increase in the use of agrochemicals. Their overuse causes serious damage to the environment. In this way, nanocomposite hydrogels are promising materials for use as carrier vehicles for the controlled release of agrochemicals, which helps reduce the damage caused by their indiscriminate use. In this work, a novel hydrogel nanostructure based on carboxymethylcellulose (CMC) and zeolite with a poly(methacrylic acid)-co-polyacrylamide (PMAA-co-PAAm) support network was synthesized. The CMC polysaccharide increased the zeolite stability in the solution. Increasing the concentration of acrylamide (AAm) monomer improved the mechanical stability of the nanocomposites. FTIR, XRD and TG results confirmed the presence of zeolite in the PMAA-co-PAAm matrices. In addition, the zeolite decreased the water absorption of the nanocomposites from 33 +/- 2 g/g to approximately 22 +/- 1 g/g, but increased the thermal stability of the nanocomposites. However, the reduction in water absorption in saline solutions was more significant in hydrogels without zeolite. Fertilizer desorption studies confirmed the controlled release behavior and this trend may be improved by zeolite structure. Thus, the presence of zeolite increased the amount of monobasic potassium phosphate (KH2PO4) release from 250 to 275 mg of fertilizer per gram of hydrogel. Controlling the water absorption and kinetic properties by adjusting the nanocomposite constituents may increase the applicability of the composites in agriculture, specifically as carrier vehicles in the controlled release of agrochemicals.