Citrus Peel–Mediated Microwave Synthesis of Ag-Modified BiVO_۴ as High-Performance Nanophotocatalysts for Congo Red Photodegradation under Visible Light

BiVO۴ and Ag-modified BiVO۴ photocatalysts were prepared using Citrus sinensis peel extract through a microwave-assisted method. The effects of extract volume, microwave irradiation time, calcination temperature, and Bi:V precursor ratio were examined to track their influence on the structural and morphological properties of BiVO۴. FT-IR confirmed the presence of phytochemical functional groups, and XRD showed monoclinic scheelite BiVO۴ with minor tetragonal zircon contributions across the synthesis conditions. SEM-EDX and TEM analyses revealed variations in particle dispersion, and Ag deposition produced small Ag nanoparticles (approximately ۷ nm) on the BiVO۴ surface. UV–Vis, BET, and XPS measurements indicated changes in optical absorption, surface area, and surface oxygen environments after Ag addition. Photocatalytic evaluation was carried out using ۱۰ ppm Congo Red at pH ۳ with ۳۰ mg catalyst under visible-light irradiation for ۱۲۰ min. Under these conditions, the sample containing ۳ wt% Ag showed the highest degradation efficiency and followed pseudo–first-order kinetics, while maintaining its activity over repeated cycles. These results suggest that citrus peel extract can be used as a biogenic medium for microwave synthesis and that controlled Ag loading provides a route to adjust the photocatalytic response of BiVO۴.

کلیدواژه ها:

Ag-modified BiVO۴ ، Citrus sinensis peel extract ، photocatalyst ، Congo red