Efficient synthesis of starch-regulated porous calcium carbonate microspheres as a carrier for slow-release herbicide

Porous calcium carbonate microspheres (PCMs), fabricated through a facile coprecipitation method regulated by soluble starch (SS), were used as carrier for prometryn (PMT), a typical herbicide, to prepare slow-release PMT. Under thermal treatment, SS molecules self-organized into nanoaggregates that bind Ca2+ through chelation and electrostatic interaction. Consequently, CO32– was introduced to the system producing CaCO3 nanoparticles (CNPs) through heterogeneous nucleation regulated by SS aggregates, and then, PCMs-SS formed. Besides, the influences of SS concentration, reaction time, and temperature on the morphology of PCMs-SS were optimized. The resulting PCMs-SS possessed a large specific surface area and functional groups and thus could efficiently load PMT through electrostatic attraction and hydrogen bonding. Additionally, the slow-release characteristics of PCMs-SS effectively controlled the migration of herbicide. PCMs-SS-herbicide possessed higher utilization efficiency and control of weeds com...