Hydrochloric Acid Treatment: An Effective Method to Enhance the Catalytic Performance of TiO2 Stellerite Composite Photocatalyst on Methyl Orange

Stellerite (a natural zeolite) was used as substrate for titanium dioxide deposition. Stellerite was treated at 363 K with hydrochloric acid solutions of different concentrations (0.2-1.0 mol L-1) for 4 hours. The resulting composite samples were characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FT-IR), BET surface area analysis and X-ray diffraction (XRD). The hydrochloric acid treatment caused the creation of micropores with similar to 1 nm diameter. The result illustrates that stellerite possesses strongly acid-resistant property in hydrochloric acid solutions with a concentration no higher than 0.4 mol L-1. The photocatalytic degradation activity of TiO2/stellerite changed remarkably when stellerite supports treated with different concentrations of hydrochloric acid were used, giving the optimum hydrochloric acid concentration of 0.4 mol L-1. The recycling of the TiO2/stellerite photocatalyst was also investigated, and the methyl orange degradation rate was 75.0% of the initial rate after four cycles.