Visible-Light Degradation of 2-Chlorophenol by TiO2 doped with Neighboring Transition Metal Cerium via Various Approaches and Operation Parameters

TiO2-related materials or processes for 2-chlorophenol (2-CP) degradation either under UV or visible light irradiations with key operational conditions was systematically reviewed in the beginning of this study. Cerium (Ce), which was neighboring transition metal elements of titanium (Ti), were individually doped with TiO2 via various methods. Three synthetic parameters in the two approaches were examined their significance by using experimental designs. It was found that the 2-CP can be 100% removal within 4-h irradiation by visible light in the synthetic condition of 0.35 mol.% Ce, 0.15 vol.% nitric acid and calcined at 600oC. Moreover, effects of three operation parameters of the as-prepared catalysts were further investigated. The most efficient condition obtained was 3 g·L− 1 catalysts at initial pH and 2-CP concentration of 7 and 10 mg·L− 1, respectively. A critical parameter, pHpzc of undoped and Ce-doped TiO2, were also determined. In addition, surface area, pore volume and size of both TiO2–based catalysts were found affected by the calcination temperatures and consequently degradation efficiency. The presenting results and mini-review were facilitated the development and applications of TiO2 in the degradation of 2-CP under lower energy radiations.