Effect of Silica Fillers on Characterization of Cellulose-Acrylamide Hydrogels Matrices as Controlled Release Agents for Urea Fertilizers

Abstract

Controlled Release Urea Fertilizers-based hydrogels matrices was synthesized by graft copolymerization of acrylamide onto the rice straw cellulose backbones in the presence of silica fillers using simultaneous graft copolymerization by gamma irradiation as initiator. Evidence of the silica presence on grafted cellulose was obtained from FTIR. X-ray diffraction analysis showed that the crystalline was reduced through silica fillers added. The effect of silica content on grafting efficiency, gel fraction, Young modulus, swelling degree, and urea loading were examined. It was found that grafting efficiency and gel fraction decrease with increasing silica added inversely with Young modulus. Water swelling and loading urea fertilizers into hydrogels matrices were conducted and the results showed that swelling degree and urea fertilizers loading increased first and then decreased with increasing silica added. The effect of the silica fillers had implications in the mechanism of controlled release urea fertilizers that diffusion-controlled mechanism became dominant, which attributed to the decreasing of urea diffusion coefficient.

Superabsorbentmaterials from grafting of acrylic acid onto Thai agricultural residues by gamma irradiation

“…[21], where graft copolymerization of AM onto Indonesian rice straw cellulose backbones using gamma radiation was studied, it was found that at the optimized gamma ray dose of 20 kGy with bleached cellulose, the equilibrium swelling degree was highest at 15.1 g/g. Moreover, with 3 wt.% added silica fillers, the value increased to 21.5 g/g [22]. The degree of swelling obtained in this study was approximately 3.7 times higher than that obtained in Ref.…”

“…Studies on graft copolymerization of AA monomer onto Indonesian rice straw cellulose backbones using gamma radiation are in Refs. [21][22][23]. Effects of irradiation dose and bleaching of cellulose using a hydrogen peroxide process were evaluated.…”

Preparation of carboxymethyl cellulose‐g‐poly (acrylamide)/montmorillonite superabsorbent composite as a slow‐release urea fertilizer

“…Urea is 1 of the most important nitrogen fertilizers due to its high nitrogen content (46%). Due to nitrogen losses by NH 3 volatilization, NO 3 − leaching, and N 2 O emission, the nitrogen urea uptake by crops is reduced by 30 to 50%, which causes great problems . So, the synthesis of superabsorbent composites (SACs) as carriers for controlled‐release agrochemicals is considered to be 1 of the best solutions for this problem .…”

“…Due to nitrogen losses by NH 3 volatilization, NO 3 − leaching, and N 2 O emission, the nitrogen urea uptake by crops is reduced by 30 to 50%, which causes great problems. 1,2 So, the synthesis of superabsorbent composites (SACs) as carriers for controlledrelease agrochemicals is considered to be 1 of the best solutions for this problem. 3 This may be due to the improvement of the soil swelling capacity and diminishing the consumption of irrigation water.…”

Usage Of Chitosan-Silica with Crosslinking Agent As A Matrix For Slow Release Fertilizer

“…Chitosan can be used as a physical barrier to fertilizers which can reduce the rate of diffusion of water into core fertilizer and diffusion of nutrients beyond the core fertilizer [2]. Silica is widely used in slow release fertilizer because it has a small particle size, and is amorphous so that it affects the release mechanism of urea fertilizer which is more directed to the mechanism of the diffusion process [3]. Glutaraldehyde was commonly used as a crosslinking agent because glutaraldehyde increases the stability of chitosan by forming intermediate compounds.…”