High foliar retention tannic acid/Fe3+ functionalized Ti-pillared montmorillonite pesticide formulation with pH-responsibility and high UV stability

The large losses and UV-light instability of traditional pesticide formulations during spraying lead to low drug utilization and a threat to the environment and human health. In this work, a tannic acid and iron ion functionalized titanium dioxide pillared montmorillonite drug sustained-release system was successfully prepared. Pillared montmorillonite showed good foliar retention after tannin modification to prevent the loss of the drug during spraying. Under the irradiation of UV light, the shielding and absorption of UV light by the montmorillonite sheet, TiO2 and tannic acid coating greatly enhanced UV stability of the avermectin (AVM). In addition, AVM@Fe-TA-TiPMt also showed pH response release due to the ion exchange and disintegration of the coating. With the disintegration of tannic acid coating and the release of tannic acid molecules, AVM was rapidly released below pH 7. AVM@Fe-TA-TiPMt exhibited enhanced insecticidal effect due to the excellent foliar retention effect and high drug release. The tannic acid-functionalized sustained-release system has achieved high foliar retention, UV stability and pH-responsive release, which is conducive to the efficient utilization of pesticides and provides valuable information for the development of clay-based pesticide formulations in the future.