Photo-Fenton-like and photo-fenton-like oxidation of Procaine Penicillin G formulation effluent

摘要

In the present study,the degradation of Procaine Penicillin G(PPG)formulation effluent by Fenton-like(Fe^/FbO:)and UV-A light assisted Fenton-like(Fe~(3+)/H_2O_2/UV-A)processes have been investigated at pH=3.The effects of different process variables such as the initial Fe~3+and H_2O_2 concentrations,reaction time and UV-A light on PPG formulation effluent degradation rates have been evaluated.Chemical oxygen demand(COD),5-day biochemical oxygen demand(BODs),total organic carbon(TOC)and acute toxicity towards the water flea Daphnia magna were selected as the environmental sum parameters to follow the performance of Fenton-like and photo-Fenton-like advanced oxidation processes on the PPG(Procaine Penicillin G)formulation effluent(COD_o=600mg/l;BOD_5=53 mg/1;TOC_o=450 mg/1).At optimum reaction conditions(i.e.[Fe~3+]=1.5 mM and[H_2O_2]=25 mM,pH=3),56% COD and 42% TOC removal where achieved by the photo-Fenton-like process after 30 min treatment time,whereas the removal efficiencies of the dark Fenton-like process were limited to 44% COD and 35% TOC for the same treatment period.The superiority of the UV-A light-assisted Fenton-like process over the dark Fenton-like reaction was more evident in terms of their effect on biodegradability improvement;the BOD_5/COD ratio increased from 0.10 to 0.45 and 0.10 to only 0.24 after application of the photo-Fenton-like and Fenton-like processes,respectively.Based on the results of acute toxicity tests it could be inferred that the photo-Fenton-like process is a suitable method for complete detoxification and partial oxidation of PPG formulation effluent.COD removal efficiency decreased from 56 to 17% for the photo-Fenton-like process and from 44 to 14% for the dark Fenton-like process in the presence of the 1214 mg/1 chloride ion(used as a free radical probe compound at acidic pH)after 30 min oxidative treatment,indicating that in both treatment processes the hydroxyl radical(~(center dot)OH)was the major oxidizing agent for PPG.