Synthesis and Characterization of Slow-Release Fertilizer Hydrogel Based on Hydroxy Propyl Methyl Cellulose, Polyvinyl Alcohol, Glycerol and Blended Paper

Abstract

In this study, biodegradable slow-release fertilizer (SRF) hydrogels were synthesized from hydroxyl propyl methyl cellulose (HPMC), polyvinyl alcohol (PVA), glycerol and urea (SRF1) and HPMC, PVA, glycerol, urea and blended paper (SRF2). The fertilizer hydrogels were characterized by SEM, XRD and FTIR. The swelling capacity of the hydrogels in both distilled and tap water as well as their water retention capacity in sandy soil were evaluated. The hydrogels had good swelling capacity with maximum swelling ratio of 17.2 g/g and 15.6 g/g for SRF1 and SRF2 in distilled, and 14.4 g/g and 15.2 g/g in tap water, respectively. The water retention capacity of the hydrogels in sandy soil exhibited higher water retention when compared with soil without the (SRFs). The soil with the hydrogels was found to have higher water retention than the soil without the hydrogels. The slow-release profile of the hydrogels was also evaluated. The result suggested that the prepared fertilizer hydrogels has a good controlled release capacity. The blended paper component in SRF2 was observed to aid effective release of urea, with about 87.01% release in soil at 44 days compared to the pure urea which was about 97% release within 4 days. The addition of blended paper as a second layer matrix was found to help improve the release properties of the fertilizer. The swelling kinetic of the hydrogel followed Schott’s second order model. The release kinetics of urea in water was best described by Kormeye Peppas, suggesting urea release to be by diffusion via the pores and channels of the SRF, which can be controlled by changing the swelling of the SRF. However, the release mechanism in soil is best described by first order kinetic model, suggesting that the release rate in soil is depended on concentration and probably on diffusion rate via the pores and channels of the SRF.

Fertilizers and Fertilization Strategies Mitigating Soil Factors Constraining Efficiency of Nitrogen in Plant Production

“…Polymer super-absorbents are macromolecular compounds capable of absorbing water or physiological fluids in amounts much greater than their mass. They can be added to the soil or to fertilizers [ 227 , 228 ]. Among other things, chitosan-based hydrogels can be used as an additive to fertilizers [ 229 ].…”

Development of hydrogel based on Carboxymethyl cellulose/poly(4-vinylpyridine) for controlled releasing of fertilizers

“…The releasing of urea is independent on concentration according to Zero order model. Based on Korsmeyer-Pappas and Higuchi models with high n value and R 2 equals to 0.97 indicates that release mechanism is Super case II transport [57][58][59][60][61]. That due to presence of carboxylic group which linked with Urea and carboxylic group's nature is highly affected by pH change of the medium.…”

Hydroxypropyl methylcellulose-controlled in vitro calcium phosphate biomineralization

“…The angular deformation of C-H bonds in HPMC is reflected by two bands at 1460 and 1382 cm À1 . 1,2 The characteristic band at 944 cm À1 and the peaks at 1063 and 1119 cm À1 are assigned to the C-C, C-O-H and C-O-C stretching vibrations of the pyranose ring in solid HPMC, respectively. 1,2 Other bands at 1631, 3478, 2837 and 2933 cm À1 are related to CQO stretching from the glucose of the cellulose, O-H stretching as well as stretching vibrations from C-H and methyl groups in HPMC, respectively.…”

“…Cellulose ethers are one of the main cellulose derivatives that are produced by substitution of hydroxyl groups to methyl, hydroxyethyl or hydroxypropylmethyl functional groups within the macromolecular backbone. [1][2][3] It has been demonstrated in previous studies that these changes can decrease the crystallinity of cellulose, whereas the water solubility and gelation properties can be improved. 4,5 Among the cellulose ethers, HPMC has been a well-known biopolymer with application in different industries including constructions, ceramics, plastics, foods, textiles and pharmaceuticals.…”