Removal of Humic Acid by Photocatalytic Process: Effect of Light Intensity
Keywords:Humic acid, photocatalytic process, titanium dioxide, light intensity.
Humic acid is commonly found in natural water as it is one of the by-products from decomposition of plants and animal residues. In a conventional water treatment process, which chlorine is common used as a disinfectant, the presence of humic acid could lead to the formation of carcinogenic substances, such as trihalomethanes and haloacetic acids. Thus, removal of humic acid from raw water before disinfection process is necessary. Photocatalytic reaction using Titanium Dioxide (TiO2) as a catalyst is one of the most effective techniques for degrading humic acid. The efficiency of this process depends on several factors; and, one of these factors is light intensity. This research investigated the effect of light intensity (35, 225 and 435 µW/cm2) and studied kinetic of photocatalytic degradation of humic acid, using commercial TiO2 Degussa P25 as a photocatalyst. Concentration of humic acid in water was monitored using UV254 absorbance and concentration of total organic compound was measured using a Total Organic Carbon Analyzer (TOC) every 30 min. The results showed that the removal efficiency of humic acid increased with increasing light intensity and then becoming asymptotic. At light intensity of 435 µW/cm2 and initial humic acid concentration of 4 mg/L with TiO2 loading of 100 mg/L was found to have highest removal efficiency, nearly 95% of humic acid measured by UV254; however, the removal efficiency of total organic compound was found only 20%. The photocatalytic degradation rate of humic acid was followed by Langmuir - Hinshelwood (L-H) kinetic models, and the reactivity constant kL–H values for the light intensity of 35, 225 and 435 µW/cm2 were found as 0.049, 0.152 and 0.178 mg L-1 min-1, respectively.
How to Cite
Authors who publish with Engineering Journal agree to transfer all copyright rights in and to the above work to the Engineering Journal (EJ)'s Editorial Board so that EJ's Editorial Board shall have the right to publish the work for nonprofit use in any media or form. In return, authors retain: (1) all proprietary rights other than copyright; (2) re-use of all or part of the above paper in their other work; (3) right to reproduce or authorize others to reproduce the above paper for authors' personal use or for company use if the source and EJ's copyright notice is indicated, and if the reproduction is not made for the purpose of sale.