Influence of Acid-Modification on Physical and Photocatalytic Properties of TiO2 Powders Prepared by Sol–Gel Method

In this work, TiO2 powders modified with different acids (hydrochloric, nitric and sulfuric) were prepared using the sol–gel method. The XRD spectra demonstrated that the proportion of TiO2 anatase phase was significantly increased after modification with different acids. SEM confirmed that the grain size was significantly refined, a porous structure was formed, and the agglomeration of the powders was improved. XPS confirmed that the different acids broke the Ti-O bond of the original TiO2, and the new bond formation inhibited the transformation of the rutile phase during the annealing process. The results of photocatalytic activity tests confirmed that the degradation efficiencies were significantly improved for the all samples after modified by the acids, where the 5% H2SO4-TiO2 shows the best degradation efficiency of 79.5% for tetracycline (TC) antibiotic under 500 W mercury lamp irradiation within 28 min, compare to the hydrochloric, nitric acids.