Encapsulation and Release of Water, Fertilizer, and Pesticide from Polyvinyl Alcohol/Attapulgite Microcapsules

A complex coacervation process using water-in-oil-in-water (W/O/W) double emulsions stabilized by polyvinyl alcohol (PVA) and attapulgite (ATP) is developed to fabricate microcapsules co-encapsulating water, fertilizers (urea and diammonium phosphate, DAP), and pesticide (diquat dibromide, DQDB), termed WFP microcapsules. The encapsulation efficiencies reach ∼73% (urea), ∼82% (DAP), and ∼58% (diquat dibromide). In sand release tests, the WFP microcapsules exhibit excellent slow-release performance: on day 1, only ∼6.9% of nitrogen, ∼8.6% of phosphorus, and ∼10.3% of diquat dibromide are released. In contrast, untreated reagents release >68% of nitrogen, >94% of phosphorus, and 30% of diquat dibromide over the same period. These results demonstrate that PVA/ATP microcapsules offer a promising integrated platform for water-fertilizer-pesticide delivery with significantly enhanced utilization efficiency.