Understanding the Adsorption Process of Imidacloprid to MCM-41

Abstract

Excessive use of imidacloprid risks environmental sustainability, necessitating safer application methods. The nanodelivery techniques have contributed significantly to this aspect with the support of various nanocarriers, whereas porous silica nanocarriers have shown promise for guest molecule delivery. In pesticide delivery, adsorption plays a crucial role in regulating the loading efficiency and release pattern. This study investigates the adsorption process of imidacloprid onto a widely used porous silica nanomaterial, MCM-41. The synthesis and structural characterizations of MCM-41 were confirmed through X-ray diffraction (XRD), surface area and porosity analysis, transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and Fourier-transform infrared spectroscopy (FTIR) before and after calcination. The synthesized MCM-41 nanomaterials showed a uniform mesoporous structure with a high surface area of 819.10 m²/g. Batch adsorption studies revealed favorable interactions between MCM-41 and imidacloprid, showing a high adsorption capacity of 104.31 mg/g, followed by effective reversibility, with 65% of the adsorbed amount released over five cycles. Physisorption, especially weak hydrogen bond interaction, played a key role during adsorption to the energetically heterogeneous MCM-41 surface. The favorable adsorption–desorption of imidacloprid to MCM-41 signifies the potential of MCM-41 to act as a carrier for imidacloprid delivery. Overall, this study paves the way for the agro-industrial application of MCM-41 in pesticide delivery.