Green synthesis and atomistic insights into starch-assisted stabilization of ZnO nanoparticles for efficient photocatalytic degradation

Abstract

This study focuses on the synthesis of ZnO nanoparticles (NPs) using maize starch as a green stabilizer. The morphological and structural properties of the synthesized materials were characterized by X-ray diffraction and Raman spectroscopy, confirming the formation of nanoscale ZnO NPs. To better understand the stabilizing role of starch in the green synthesis, the interaction between ZnO and maize starch was modeled using atomistic calculations. The photocatalytic activity of the synthesized ZnO NPs was evaluated for the removal of metoprolol tartrate (MET), extracted from a commercial Presolol ^® tablet, in ultrapure water under simulated solar (SS) and ultraviolet light–emitting diodes (UV–LED) irradiation. Significantly higher activity was observed under UV–LED irradiation, achieving 77.1 % MET degradation and 41.6 % mineralization after 240 min. Mechanistic investigations, supported by scavenger experiments, revealed that hydroxyl radicals, superoxide anion radicals, and photogenerated holes are the dominant reactive species responsible for MET degradation. The combined experimental and computational results demonstrate that starch-assisted synthesis effectively controls nanoparticle growth and stability, leading to enhanced photocatalytic performance. These findings highlight the potential of green-synthesized ZnO NPs for sustainable water treatment applications.