Photocatalytic degradation of pollutants based on semiconductor quantum dots (QDs) can be applied in wastewater purification methods. However, application of free QDs was associated with some difficulties, such as oxidation and agglomeration of QDs and difficulties in separation. As a solution to these problems, we have proposed the production of mesoporous SBA-15 supported CdS quantum dots as a more stable photo-catalyst. The efficiency of these prepared nanocomposites was examined for photocatalytic degradation of Alizarin, as an organic pollutant. Results demonstrated that the proposed material is a promising catalyst for photocatalytic degradation of dyes in wastewaters. The kinetic and adsorption isotherms of photocatalytic degradation process were also studied and a detailed mechanism proposed for degradation process. The proposed mechanism was studied using free radicals trapping experiments; results demonstrated that the ∙O− 2 radicals are active intermediates and have an important role in the photodegradation mechanism.
