Monitoring of Cu2+ release from controllably synthesized nano-copper pesticides

Abstract

Copper-based nanopesticides hold significant promise for agricultural applications. However, a critical challenge that persists is the need for effective control over the release of Cu2+. To this end, this study systematically investigated the Cu2+ release characteristics of Cu-based NPs with varying morphologies, species, and coating agents. It is found that CuO NPs exhibited extremely low Cu2+ concentration, rendering them ineffective for plant disease control. Cu(OH)2 nanowires cannot continuously release Cu2+ due to its larger size and enhanced stability. Conversely, Cu(OH)2 NPs exhibited sustained Cu2+ release, albeit at a slower rate. Modification with surfactants could significantly affect the Cu2+ release behavior, particularly the coating of carboxymethyl starch, which notably promoted Cu2+ release from Cu(OH)2 NPs, achieving sustained release for 27 days. Furthermore, carboxymethyl starch-coated Cu(OH)2 particles could consistently release Cu2+ in the pH range of 5–7. This finding may offer the inspiration of long-lasting control of plant diseases.