PHOTOCATALYTIC DEGRADATION OF FORMIC ACID INAQUEOUS WITH Ni DOPED TiO2 COATED ON SILICAGEL

Abstract

Formic acid (FA) photocatalytic degradation using nickel doped TiO2 (Ni-TiO2) coated on silica grain (Ni-TiO2/SiO2) by sol-gel method has been studied. Nickel with a different molar ratio as 0.2, 0.4, and 0.8 % mole was used in this study. Samples were characterized by XRD, SEM, and UV-vis spectroscopy. Conditions such as dark, ultraviolet-visible and visible light were performed to assess the photocatalytic ability of Ni-TiO2/SiO2. The results showed that, catalyst samples had uniform nanosize, anatase crystalline structure and the band-gap energy of Ni-TiO2/SiO2 was lower than that of TiO2/SiO2 sample. The highest photocatalyst activities were obtained at 0.2 % mol of Ni for both irradiations. The FA concentration was not changed in the dark condition. Under ultraviolet-visible irradiation, FA concentration decreased from 10-4 mM to 2.10-5, 7.10-5 and 9.10-5 mM with 0.2, 0.4 and 0.8 % mole of Ni, respectively. With visible light condition, FA concentration decreased from 10-4 mM to 7.10-5 mM when Ni dopant amount was 0.2 % mole. Change in FA concentration was negligible with 0.4 and 0.8 % mole of Ni dopant amount. It proved that the photocatalytic activity of Ni-TiO2/SiO2 under visible light irradiation was generated by doping a small amount of nickel into TiO2. However, under visible light irradiation with 420 nm filter, FA photodegradation of Ni/TiO2/SiO2 increases when Ni dopant content increases from 0 % mole to 0.8 % mole.