Design of Experiments for the Synthesis of MMT/TiO2/Ag Composites: Integrating Adsorption and Photocatalysis under Artificial UV and Natural Sunlight for Ethylene Degradation.

Postharvest deterioration caused by ethylene (C2H4) is a major challenge for global food security, leading to significant losses of perishable products like bananas. In this study, we present the synthesis and optimization of a multicomponent photocatalyst based on montmorillonite (MMT), titanium dioxide (TiO2), and silver (Ag), designed for efficient ethylene remediation. The catalysts were prepared via wet impregnation and characterized using FE-SEM, EDS, and UV-vis reflectance spectroscopy, which confirmed the successful integration of components and a homogeneous elemental distribution. The bandgap energies were determined to be in the range of 3.02 to 4.10 eV, with MMT-rich samples showing values around 3.12 eV. Through a 23 factorial design, the performance was evaluated under three distinct scenarios: adsorption, artificial UV photocatalysis, and natural sunlight-driven photocatalysis. Sample Amt 09 (1.5% TiO2 and 1% Ag) achieved an ethylene removal of over 92% in the artificial UV photocatalysis scenario. Sample Amt 10 (5% MMT, 1.5% TiO2, and 1% Ag) stood out with high performance across all scenarios, suggesting synergistic effects between adsorption and catalytic degradation. Furthermore, an optimized formulation (5% MMT and 2.73% TiO2) achieved 65% ethylene removal under UV light and 47% under natural sunlight. These findings highlight the potential of MMT/TiO2/Ag composites as sustainable, light-driven solutions for postharvest management, offering a scalable platform to extend the shelf life of fresh produce and reduce global food waste.