Release Mechanisms and Kinetic Models of Gypsum–Sulfur–Zeolite-Coated Urea Sealed with Microcrystalline Wax for Regulated Dissolution

Abstract

In this study, a mineral-based coated urea was fabricated in a rotary pan coater using a mixture of gypsum/sulfur/zeolite (G 25 S 25 Z 50 ) as an effective and low-cost coating material. The effects of different coating compositions on the dissolution rate of urea and the crushing strength and morphology of the coated urea were investigated. A 25:25:50 (wt %) mixture of gypsum/sulfur/zeolite (G 25 S 25 Z 50 ) increased the coating effectiveness to 34.1% with the highest crushing strength (31.06 N). The effectiveness of coated urea was further improved to 46.6% with the addition of a microcrystalline wax (3%) as a sealant. Furthermore, the release mechanisms of various urea fertilizers were determined by fitting the release profiles with six mathematical models, namely, the zeroth-order, first-order, second-order, Higuchi, Ritger & Peppas, and Kopcha models. The results showed that the release mechanism of the uncoated urea and all other coated urea followed the Ritger & Peppas model, suggesting the diffusional release from nonswellable delivery systems. In addition, due to the increased mass-transfer resistance, the kinetic constant was decreased from 0.2233 for uncoated urea to 0.1338 for G 25 S 25 Z 50 -coated urea and was further decreased to 0.0985 when 3% Witcovar 146 sealant was applied.

Development and testing of zinc sulfate and zinc oxide nanoparticle-coated urea fertilizer to improve N and Zn use efficiency

“…The water molecules generate osmotic differences internally inside the coating layer ( Zafar et al., 2021 ). This process can be seen in Figure 2A , which is similar to the release patterns demonstrated previously ( Beig et al., 2020b ; Beig et al., 2020c ; Eghbali Babadi et al., 2021 ). In the current study, ZnO-NPs provided better results than ZnSO 4 bulk salt coatings in terms of slowing the release rate.…”

“…The crushing strength of coated urea was highly dependent on the nature of the coating material and the percentage of the coating used. Higher coating percentages offered high values, which are the result of the improvement of nutrient delay ( Babadi et al., 2015 ; Beig et al., 2020b ; Eghbali Babadi et al., 2021 ). The blending of molasses with ZnSO 4 or ZnO-NPs creates a uniform layer because of its adhesive nature ( Irfan et al., 2018 ; Arfiana et al., 2019 ; Pamungkas et al., 2020 ).…”

The Formation of Self-Assembled Nanoparticles Loaded with Doxorubicin and d-Limonene for Cancer Therapy

“…Several kinetic models were investigated to analyze the data of DOX release from the three developed self-assembled nanoparticles that were computed using DDsolver . The investigated models were the Korsemeyer–Peppas ( m t / m ∞ = kt n ), Peppas–Sahlin ( m t / m ∞ = k 1 t m + k 2 t 2 m ), and Higuchi models ( m t / m ∞ = kt 1/2 ). − The linear regression ( R 2 ) and Akaike information criterion (AIC) were measured.…”

Osmanthus fragrance polyurethane/silkfibroin‐based double‐shellmicrocapsules for aromatic leather with sustained release fragrance

“…The release data were analysed by applying the Ritger‐Peppas model, the fitting equation was described as follow:where indicates the cumulative release at time t, and is the cumulative release at infinity, k (6.544) indicates the release rate constants, n (0.329) is the release exponent, reflecting the diffusion mechanism. The release exponent of the equation is lower than 0.43, 45 indicating that the release characteristics of OF@PU/SF microcapsules is dominated by a Fickian diffusion mechanism. Therefore, it can be concluded that the release of OF@PU/SF microcapsules accords with the characteristics of typical fragrance release from microcapsules or microspheres.…”