Optimization of pharmaceutical wastewater treatment by solar/ferrioxalate photo-catalysis

The degradation of a pharmaceutical wastewater using a ferrioxalate-assisted solar/photo-Fenton system has been studied. The photochemical reaction was carried out in a pilot plant consisting of a compound parabolic collector (CPC) solar reactor. An optimization study was performed combining a multivariate experimental design and Neuronal Networks that included the following variables: initial concentrations of H2O2, catalyst Fe (II) and oxalic acid (H2C2O4), temperature and solar power. Under optimal conditions, 84% TOC (Total Organic Carbon) removal was achieved in 115 min. Oxalic acid had a positive effect on mineralization when solar power was above 30 W m−2. The minimum amount of H2O2 to degrade 1 mol of TOC was found to be 3.57 mol. Both the H2O2 conversion efficiency and the degree of mineralization were highest when the oxalic/Fe(II) initial molar relation was close to 3. HO radicals were the main oxidative intermediate species in the process, although hydroperoxyl radicals (HO2) also played a role. [Display omitted] •Photo-ferrioxalate system was applied to degrade pharmaceutical wastewater.•84% TOC removal was achieved in 115 min.•The H2O2 efficiency depends on the oxalic/Fe(II) molar relation.•1 mol of TOC could be degraded with 3.57 mol of H2O2.•OH radicals were the main oxidative intermediate species in the process.