Triazolone/alginate-zinc (II)-montmorillonite sustained release system with improved adsorption capacity and pH-sensitivity

Developing effective sustained release system is an efficient way to prevent the pollution from overused pesticide. Hence, a highly efficient sustained release system was developed using zinc (II) modified montmorillonite (Zn–Mt) prepared by ion exchange from sodium montmorillonite (Na–Mt) with zinc nitrate. Zn–Mt was modified by sodium alginate (ALG) to further improve its sustained release performance and pH-sensitivity. The results indicated that triazolone was supported on the zinc modified montmorillonite through the coordination bond from zinc ion. The zinc ion in the Mt also played a similar role as calcium ion to induce ALG crosslinking which made ALG highly dispersed in the pores of Mt. ALG interacted with Zn 2+ from Mt through electrostatic interaction and winded with triazolone to form a barrier for the sustained release system. As a result, the adsorption capacity of ALG–Zn–Mt (17.75 mg/g) was improved comparing with Na–Mt without modification (14.52 mg/g). The sustained release performance of ALG–Zn–Mt showed also significant pH-sensitivity in accordance with the stability of ALG.