Visible light assisted degradation of Atenolol by Fe-TiO2: Synthesis, characterization, optimization and mechanism

Photo stimulation of Fe doped TiO2 (Fe-TiO2) under visible light irradiation (i.e. 300 W Halogen lamp) was employed for atenolol (ATL) removal from domestic wastewater effluent. As a first step, Fe nanoparticles (NPs) were synthesized using Acacia Catechu pods, doped with TiO20, characterized using UV-vis spectrometry, SEM, TEM, FT-IR, XRD and XPS, and subsequently, used for photo degradation experiments. The experimental variables, viz., initial contaminant concentration (10-50 mg/L), pH (6-12), photocatalyst concentration (500-2000 mg/L) and reaction time (30-180 min.) were optimized using response surface methodology (RSM). A positive correlation between catalyst dosage and ATL degradation was observed in RSM up to a catalyst dose of 1.25 g/L when pH was between 7 and 9. After 105 min, a maximum of 85 % ATL removal was achieved at pH 9, 1.25 g/L of Fe-TiO2 dosage at an initial ATL concentration of 10 mg/L. The obtained RSM model demonstrated a high correlation between experimental and predicted values of ATL removal (R-2 similar to 0.95). Cleavage of ether bond, hydroxylation of aromatic ring and oxidation of amine moieties were responsible for the degradation of ATL by visible light activated Fe-TiO2. The electrical energy consumed per order (EE/O) was evaluated to ascertain the efficiency of irradiation intensity and EE/O values were found to increase with increase in the initial ATL concentration. Overall, the green synthesized Fe-TiO2 could be an useful alternative for commercial photocatalysts.