Photocatalytic Decolourization of Chlorophyllins E141(ii) on Irradiated TiO2

摘要

This paper presents the results of research on the possibility of photodecolourization of trace amounts of copper complexes of chlorophyllins (E141(ii) commercial dye) in water (sewage). Experiments were carried out in model UV-VIS/E141 (ii)/TiO2/H2O and UV-VIS/E141(ii)/H2O systems. The degree of decolourization of the dye was determined speetrophotometrically. The loss of dye in a UV-VIS/E141(ii)/TiO2/H2O system was directly proportional to the initial substance concentration and ranged from 55% to 82%, depending on the initial concentration of the dye in the solution. Kinetic studies confirmed that over a range of examined concentrations of dye E141(ii), the photocatalytic decolourization process occurs in accordance with the commonly acknowledged Langmuir-Hinshelwood model. The course of changes in pH upon exposure indicates the formation of acidic derivatives of chlorophyllins. We found that the amount of photodegradable dye strongly depends on the initial pH of the solution. The increase of the pH of the solution inhibited the process of photocatalytic decolourization of E141(ii), whose yield reached a minimum value at pH 8. Results of this study confirm that the photocatalytic processes can be an alternative to traditional methods of food industry sewage treatment.