Catalytic photodegradation of alkyl surfactants

An attempt to identify intermediate and final products of photocatalytic degradation of sodium dodeylbenzensulfonate (DBSNa) in aqueous solution was carried out. Synthetic samples of DBSNa containing TiO(2) as catalyst were treated in a solar concentrator device. Samples were taken at regular intervals and analyzed by GC/MS. Two main types of signal were observed in the total ion chromatograms. The first group includes signals absent in the untreated sample that appeared during the first phases of the experiment and decreased toward the end. The second group comprised species already present in the untreated sample. There were signals in both groups probably because of stable oxygenated molecules that were accumulated to the ene of treatment, indicating partial mineralization. Results clearly showed that degradation dynamic is complex. The detergent is fragmented into other products that undergo further reactions. The species distribution towards the end of the process is difficult to predict since it depends on a large number of variables including adsorption, reaction rates and the nature of the intermediate products. It is necessary to continue the study to determinate if these molecules are destroyed within the system for longer illumination times.