The investigation of the basic fuchsin dye photocatalytic degradation in aqueous media using stabilised Span 80 and synthesized ultrasonically CuO Nanoparticles (NPs)

Abstract

This study investigates the synthesis and photocatalytic efficacy of copper oxide Nano Particles (CuO NPs) for dye removal from water. CuO NPs are synthesized via a sonochemical reduction method in an alkaline aqueous medium, using copper sulfate pentahydrate (CuSO₄·5H₂O) as a precursor and Span 80 as a reducing and stabilizing agent. Characterization is conducted using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Brunauer–Emmett–Teller (BET) surface area analysis, and UV–visible spectroscopy. The results reveal that the NPs exhibit an irregular shape, with an average length of 75 nm, an optical band gap of 2.7 eV, and a surface area of 10.7 m²/g. The photocatalytic degradation of basic fuchsin dye under UV light was achieved with an 81.3% removal rate within 30 min at natural pH (5.4), 20 ± 2 °C, and 400 rpm, with an initial dye concentration of 10 mg/L and a mass-to-liquid ratio (r) of 1. It was observed that increasing the initial concentration of the dye resulted in a reduction in the efficiency of the degradation process. However, an optimized catalyst dose of 200 mg (r = 2) was found to enable an 87.3% removal within 10 min. Under alkaline conditions (pH 8), the photocatalytic efficiency was observed to increase further, reaching 92.78%. The degradation process was found to follow a pseudo-first order kinetics. The scavenger tests indicate the singlet oxygen as the primary reactive oxygen species. Total organic carbon (TOC) analysis shows a 65% reduction in organic content, supporting the proposed dye degradation mechanism. These findings demonstrate the potential of CuO NPs as effective photocatalysts for environmental dye removal applications.