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 Ca 2+ through chelation and electrostatic interaction. Consequently, CO 3 2– was introduced to the system producing CaCO 3 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 compared to traditional herbicide, thus it exhibits promise for future applications.