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PHB and Montmorillonite Clay Composites as KNO3 and NPK Support for a Controlled Release

Souza, Josiane Lima, de Campos, Adriana, França, Débora, Faez, Roselena
Journal of polymers and the environment 2019 v.27 no.9 pp. 2089-2097
NPK fertilizers, ammonium, anions, biodegradability, clay, leaching, melting, montmorillonite, nitrogen, nutrient uptake, nutrients, phosphates, phosphorus, poly-3-hydroxybutyrate, potassium, potassium nitrate
In order to improve nutrient uptake by plants and at the same time decrease losses by leaching, polymeric compounds based on biodegradable poly(3-hydroxybutyrate) (PHB) and montmorillonite clay (MMt) were melt processed with KNO₃ and NPK fertilizers (Fert). We present a comprehensive analysis of releasing profile of the potassium (K⁺), nitrogen (NH₄⁺ and NO₃⁻) and phosphorous (PO₄³⁻) from PHB/MMt/fertilizer at 90/0/10, 50/0/50, 80/10/10, 40/10/50, 25/25/50 formulation. The amount and type of the fertilizer and the presence of clay delineated the release of the cations and anions from the matrix. Cations released faster than anions through MMt composites due to cations–MMt interactions and its diffusion through MMt phase. The nutrients delivery from composites was lower than pure fertilizer. Composites formulations with smaller amount of PHB and MMt (25 wt%) were enough to encapsulate the fertilizer and delay the ions releasing. Further, the simple method of preparation also attains the sustainability of the whole process.