Selective photocatalytic removal of procaine – comparison of molecularly imprinted and non-imprinted TiO2 material

Pharmaceuticals are ubiquitois in our daily lives and are therefore easily enter the environment. Such invisible small organic molecules pollute every part of environment; and constitute a major problem for the entire ecosystem. Conventional water treatment techniques are unsuitable for this type of pollutants, so advanced oxidation methods such as photocatalysis are being investigated. Due to the more economical and simpler photocatalytic performance, a catalyst was prepared in this work by depositing a TiO2 film on an Al2O3 ceramic foam substrate. The photocatalytic activity of procaine under UV-A light was investigated through experiments of optimization of reaction conditions by changing the pH and initial drug concentration. The obtained results indicated the procaine is degraded most rapidly in an alkaline medium (pH 10) and at a concentration of 10 mg/L. Considering that degradation is generally very slow at different concentrations and pH values (removal half-lives between 110 and 690 min), a different type of catalyst was used to improve the photocatalytic efficiency for procaine. Indeed, the photocatalyst was prepared in the same way as the previous one, only with the addition of a pollutant molecule to the reaction mixture. The acid-catalyzed sol-gel reaction led to the formation of imprinted procaine molecules on a TiO2-Al2O3 ceramic. The photocatalytic experiments were repeated under the same reaction conditions, and the results highlighted the importance of developing new catalysts such as molecularly imprinted materials, as these increased the selectivity of removal of non-degradable molecules such as procaine.