Sunlight-Induced Photocatalytic Removal of Paracetamol Using Au-TiO2 Nanoparticles

Abstract

Using sunlight as the driving force for photocatalytic processes holds great promise for sustainability. As a starting point for developing a material capable of degrading aquatic pollutants using solar energy as a stimulus, this work focuses on synthesizing Au-TiO₂ nanocomposites using the deposition-precipitation method. Characterization of Au-TiO₂ nanoparticles was performed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Transmission Electron Microscopy (TEM). A model pollutant, paracetamol, was used to test the synergetic effect of Au (0.05 wt%) nanoparticles (NPs) with TiO₂ on photocatalytic activity. The influence of the parameters pH, loading (0.4, 0.8, and 1 g/L), pollutant concentration (20, 30, 40 ppm), and contact time (30, 60, 90, 120, 150, and 180 min) was studied by exposing the NPs to solar radiation. The photocatalytic degradation was most effective at a contact time of 3 h, an initial concentration of 20 ppm, and a pH of 6.8. Under these conditions, paracetamol in 1 g/L of Au-TiO₂ nanocomposites can be degraded by more than 99.17% under solar irradiation. As a result of the Au-TiO₂ composite's ability to successfully serve as a photocatalyst using sun radiation, water purification processes can be more widespread, cost-effective, and environmentally friendly.

Keywords: Au-TiO2 catalyst; paracetamol; photocatalytic degradation; solar light; water remediation.

Figure 1

Photographs of the experimental setup to assess the degradation of PAR using Au-TiO₂ nanoparticles: (a) under solar radiation, where the Erlenmeyer contains the contaminant solution and nanoparticles while being magnetically stirred and powered by a solar panel that collects clean sunlight energy; (b) under a UV lamp.

Figure 2

Scanning electron microscopy images of Au-TiO₂ nanoparticles (a) before contact and (b) after contact with the paracetamol solution; (c) XRD pattern of Au-TiO₂ before (1) and after (2) paracetamol degradation; (d) FTIR spectra of Au-TiO₂ before and after paracetamol degradation.

Figure 3

Study of photodegradation of paracetamol using sunlight radiation: (a) control process with C_PAR = 20 mg/L, C_catalyst = 1 g/L and free pH 6.8, for 120 min; (b) effects of initial concentration (20, 30 and 40 mg/L); (c) different doses of Au-TiO₂ catalyst (0.3, 0.8 and 1.0 g/L); (d) impact of pH in solution (pH = 3, pH = 6.8 and pH = 10).

Figure 4

The impact of the irradiation source on the photocatalyst’s degradation of PAR in 180 min (C_PAR at 20 mg/L, C_catalyst at 1 g/L, and a pH of 6.8).

Figure 5

(a) UV–Vis spectra of paracetamol degradation under different sun irradiation times at pH = 6.8; (b) chemical oxygen demand (COD) at different times.

Figure 6

Photodegradation of paracetamol over three catalytic cycles in sunlight (C_PAR = 20 mg/L, C_catalyst = 1 g/L, and pH 6.8).