Fenton and Photo-fenton Oxidation Processes for Degradation of 3-Aminopyridine from Water

Abstract

3-Aminopyridine (3AP), used in manufacture of anti-inflammatory drugs and also as a plant growth regulator is one of the emergent contaminant, because of its toxic and carcinogenic potential and hazardous effect on natural environment. The objective of present study was therefore to investigate chemical treatment like the advanced oxidation technologies employing the classic Fenton and Photo-Fenton oxidation wherein effect of operating conditions like pH, Hydrogen peroxide (H2O2), Iron salts (both ferrous and iron extracted from laterite soil) and reaction time are optimized using synthetic 3-Aminopyridine solutions. In the present study, for 3AP conc. ranging from [10-80 mg/L] under Fenton's oxidation at pH 3, optimum ratio of [H2O2]/[Fe²⁺]:: [24–40]/[1] showed upto [90-77%] removal efficiency. Studies on use of laterite iron replacing the traditional ferrous iron, also showed comparable removal efficiencies upto [82-65%] for [H₂O₂]/[laterite iron]:: [32–53]/[1]. Moreover Photo-Fenton oxidation studies showed 100% removal for conc. range (10- 30 mg/L) under both iron salts. For Fenton's oxidation, optimum reaction time of 5.0 hrs for 10-30 mg/L to 7.0 hrs for 40- 60 mg/L and finally to 8.5 hrs for 70-80 mg/L of 3AP was required. Whereas photo-Fenton reaction studies required much less reaction time equal to 1.5 hrs for 10-30 mg/L to 2.0 hrs for 40-60 mg/L and 4.0 hrs for 70-80 mg/L. Also Chemical oxygen demand (COD) removal was increased in case of Photo-Fenton oxidation indicating improved mineralization. Fenton and photo-Fenton methods can be considered as an effective advanced oxidation methods at ambient conditions. Also iron extracted from laterite soil can be used effectively in Fenton's reagent instead of traditional ferrous salts to treat polluted water bodies containing 3-Aminopyridine.