LAUSR

Abstract The degradation of diphenhydramine hydrochloride (DPH), via UV–vis/H 2 O 2 , Fenton, photo-Fenton and photocatalysis processes, was studied under different radiation sources. In addition, the Fenton and photo-Fenton processes at acid pH and circumneutral pH have been compared. The importance of the source of irradiation, UV-C (λ = 254 nm), black blue lamps (BLB, λ = 365 nm) and simulated solar radiation (SB, SolarBox), was investigated at lab-scale. Moreover, compound parabolic collectors (CPC), at pilot plant scale with sunlight, have been also applied in photocatalytic treatments. Photo-Fenton process employing black blue lamps gave the best DPH abatement (100% of DPH conversion at 10 min for acid pH and 20 min for circumneutral pH), using the highest Fe 2+ (5 mg/L) and H 2 O 2 (150 mg/L) concentrations at 50 mg/L of initial DPH concentration. Using Fenton, 100% of DPH conversion was reached at 30 min for both pHs tested. In the case of UV-C/H 2 O 2 , 100% of DPH elimination was achieved in 20 min using 150 mg/L of H 2 O 2 . In the photocatalytic process, using 0.4 g TiO 2 /L, after 60 min of irradiation, only 35.7% and 8.7% of DPH conversion have been obtained in SB and CPC, respectively. The DPH degradation in the photocatalytic process was greatly enhanced adding H 2 O 2 . In all the cases, increasing the H 2 O 2 dose enhances the reaction rate due to higher OH production. However, not significant mineralization was obtained. The highest DPH mineralization was 36.8% and 38.5% of TOC reduction with photo-Fenton in BLB lamps using 150 mg/L of H 2 O 2 and 2.5 mg/L of Fe 2+ , for acid pH and circumneutral pH, respectively. The major reaction intermediates these processes were identified by ionization/mass spectrometry and a DPH photo-degradation structures was proposed.