Study of iron sources and hydrogen peroxide supply in the photo-Fenton process using acetaminophen as model contaminant

BACKGROUND: The aim of this study was the evaluation of iron (II) D-gluconate and iron (II) sulfate as iron sources for the photo-Fenton process at initial neutral pH. Acetaminophen was used as the contaminant for this purpose. The evaluation was carried out at laboratory and pilot-plant scales. In addition, hydrogen peroxide dosage was analyzed in order to decrease reactant consumption. RESULTS: 20 mg Fe L1 was added as iron salt or iron D-gluconate; hydrogen peroxide dosage proved to be efficient when using iron sulfate, obtaining similar mineralization levels for one large H2O2 addition, two smaller additions and continuous dosage (78%, 74% and 78% mineralization, respectively). However, when D-gluconate was used, H2O2 dosage resulted in a slower process rate: 74% mineralization for one large H2O2 addition versus 49% mineralization for two smaller additions. CONCLUSIONS: Results showed that iron complexes could form between iron and degradation by-products increasing reaction efficiency. The ratio between the dissolved organic carbon concentrations of the contaminant and the iron complex proved to be important as well. H2O2 dosage confirmed that two reactant additions led to the best results, which was then corroborated with real wastewater. (c) 2012 Society of Chemical Industry