Tannic acid-iron(III) complex functionalized porous calcium carbonate as pesticide carrier for pH-controlled release

Nanocomposites have gained extensive interest in improving control efficacy and reducing usage amount of traditional pesticides. In this study, a complex of porous CaCO3 and tannic acid-iron(III), named as PCC@TA(FeIII), was fabricated and used as carrier for prometryn (PMT) to obtain a pH-controlled release herbicide of PCC/PMT@TA(FeIII). Under neutral pH condition, the PMT release rate from PCC/PMT@TA(FeIII) was merely 19 % while reached about 80 % at pH 5.5 and 8.5. Such pH controlled-release behavior of PMT was probably related to the pH-dependent structure transformation of PCC@TA(FeIII). The release kinetic mechanism was in conformity with the parabolic diffusion model. Pot experiment result indicated that PCC/PMT@TA(FeIII) showed a higher control efficacy against Setaria viridis compared with PMT alone. Additionally, PCC@TA(FeIII) could effectively reduce the leaching loss of PMT in soil and show a good biosafety. Thus, this work provides a novel approach to improve control efficacy and relieve environmental pollution risks of pesticide.