Poly(hydroxybutyrate)-based systems behavior on the controlled release ofNPKfertilizers

Here we investigate the behavior of controlled-release systems based on poly(hydroxybutyrate) (PHB) to propose an actuation mechanism in a designed environment. Two formulations were produced employing 5% pure NPK fertilizer or 30% of bentonite nanoparticles (Bent) previously modified with NPK. The polymeric composites were obtained by melt processing and their thermal properties evaluated. The release of active compounds was evaluated by conductometric analysis in aqueous solutions at different pHs for 30 days, and the results were modulated by the Korsmeyer-Peppas model. Also, the systems were evaluated for their biodegradation characteristics using different soil types to generate a decomposition profile. In general, the systems showed a good release control, with 40% and 50% of fertilizer being released in 30 days, depending on the conditions and type of polymeric composite employed. The model indicated a linear release of active compounds in the first 30 days, according to the Fick diffusion. Additionally, the compounds were relatively stable in the first 30 days when exposed to biodegradation, being degraded faster speed after this. The efficiency and applicability of the systems were confirmed by the germination tests, which showed that both systems containing NPK favored plant growth, while the system in which the active agents had been previously incorporated into nanoparticles provided a reduction in the waste of agrochemicals. Thus, a novel mechanism of action for polymeric controlled release systems based on thermoplastic biopolymers was determined, supporting more efficient industrial processes.