Bio-based substances from urban waste as auxiliaries for solar photo-Fenton treatment under mild conditions: Optimization of operational variables

tThe use of soluble bio-based organic substances (SBO) obtained from urban wastes to expand the pHregion where the photo-Fenton process can be applied has been investigated in this study. For thispurpose, a mixture of six pollutants, namely acetaminophen, carbamazepine, amoxicillin, acetamiprid,clofibric acid and caffeine, at an initial concentration of 5 mg L−1each, has been employed. Surfaceresponse methodology, based on the Doehlert matrix, has shown to be a useful tool to determine theeffect of pH (in the range 3–7), concentration of SBO (15–25 mg L−1) and iron (2–6 mg L−1) on the per-formance of the photodegradation of the studied pollutants, measured by their half-life. Results indicatethat, at high SBO concentration, the optimum pH shifts in most cases to a higher value (between 3 and4) and that a significant loss of efficiency of the process was only observed at pH values above 5. Aniron concentration of 4–5 mg L−1and an amount of SBO of 19–22 mg L−1have been determined to be theoptimal conditions for the degradation of most of the studied pollutants at pH = 5.