Preparation and characterization of biogenic CaCO3-reinforced polyvinyl alcohol–alginate hydrogel as controlled-release urea formulation
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A slow-release fertilizer formulation was prepared by incorporation of urea in polyvinyl alcohol–alginate hydrogel core followed by deposition of calcium carbonate coating using HCO3−/CO32−-rich alkaline cell-free ureolytic culture broth. High urea encapsulation efficiencies were evident in both CaCO3-reinforced (23.48% w/w) and regular (38.71% w/w) hydrogel matrices. Deposition of carbonate over the matrix surface in the reinforced hydrogel was evident from scanning electron microscopy and typical FTIR band near 1465 cm−1 due to C–O stretch of carbonate ion. Aqueous phase release behaviour was not significantly different between the two hydrogel variants. In the soil column, two-stage urea release pattern (i.e. a slow followed by a fast) was eminent that can extend into hours. Therefore, the modified hydrogel for controlled release could be expected to have wide potential application as slow-release fertilizer in agriculture.
KeywordsBiocalcification Controlled release Fertilizer Soil column Urea
Nisha Stanley is the first author of this study and was responsible for collecting the data, doing experiments and sample analysis. Biswanath Mahanty, the second and corresponding author, prepared the manuscript including graphs and figures. Both the authors equally contributed to the literature review, formulating background of the study. All authors have read and approved the final manuscript.
Compliance with ethical standards
Conflict of interest
No potential conflict of interest is reported by the authors.
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