Evaluation of the efficiency of the TiO2 /UV nano-photocatalytic process in the removal of humic and fulvic acids from aqueous solutions

Abstract

Background: Removing natural organic substances from drinking water sources is necessary to prevent the formation of toxic and carcinogenic disinfection by-products (DBPs). The nano-photocatalytic oxidation process to remove these substances is easier, faster, cheaper, and more efficient than other methods. Methods: This study investigated the efficiency of the TiO2 /UV nano-photocatalytic process in removing humic acid (HA) and fulvic acid (FA) from aqueous solutions. Batch tests were performed to investigate the effect of various parameters such as contact time (15, 30, 45, 60, and 75 minutes), initial pH (4, 7, and 9), initial HA and FA concentration (0.5, 1, 2, 5, and 7 mg/L-1), TiO2 dose (5, 10, 15 and 20 mg/L-1), and different UV irradiation (8 W and 16 W) for the removal of HA and FA from aqueous solutions using TiO2 /UV at room temperature (20±3 °C). The equilibrium adsorption data and the standard parameters were evaluated. Data were analyzed using SPSS version 25. Results: The efficiency of this process in optimal conditions (pH: 4, anatase TiO2 : 10 mg/L-1, irradiation time: 60 min, UV=16 W) for removing humic and fulvic (initial HA concentration: 2 mg/L-1 and initial FA concentration: 5 mg/L-1) was 89% and 92%, respectively. The analysis of the experimental isotherm data showed that in the adsorption process of HA and FA on TiO2 /UV, the Langmuir isotherm and the first-order reaction had the best fit with the experimental data. Conclusion: TiO2 /UV nano-photocatalytic process is suitable for the photo-degradation and removal of HA and FA in aqueous solutions.