Facile sol-gel preparation of amorphous TiO2 nanoparticles under pH of 8 for synergistic adsorption-photocatalytic degradation of tetracycline

In this work, an amorphous TiO2 nanoparticle (8-AT) was prepared via the sol-gel route in which the pH of sol was facilely adjusted to 8 with ammonia. The characterization results of physicochemical properties revealed that as-prepared 8-AT had the particle size of 20–24 nm and specific surface area of 365.68 m2/g. The degradation of 8-AT for 20 mg·L−1 tetracycline (TC) aqueous solution achieved 93.9% within 30 min dark reaction and 60 min visible light irradiation, which was 1.3 and 2.0 times higher than that of anatase TiO2 and P25. Moreover, 8-AT can maintain a degradation capacity of 82.7% for the concentrations up to 50 mg·L−1 of TC, and the degradation rate decreased slightly by 11.86% after five cycles. Based on the synergistic adsorption-photocatalytic activity of 8-AT catalyst, the possible degradation mechanism of TC was proposed. This work provided a facile method for obtaining amorphous TiO2 through adjustment of pH and a new idea for developing efficient photodegradation catalyst.