Removal of humic acid from aqueous solution using photocatalytic reaction on perlite granules covered by Nano TiO2 particles

Humic acid (HA) constitutes a large portion of natural organic matter (NOM), and is the main precursor of toxic and cancerogenic Trihalomethanes compounds, formed during chlorination of drinking water. Therefore, it is essential that the humic acid be eliminated from water before treating it. The present study aims to investigate the photocatalytic degradation of humic acid (HA) using TiO2 nanoparticles immobilized on perlite granules (TIP), irradiated by UV light in a photoreactor. Samples of coated perlites were prepared by a dip coating method using a commercial powder of TiO2. Characteristics of the prepared samples were evaluated by X-ray and scanning electron microscope techniques. Results showed no significant changes in the structure of TiO2 and a relative uniform morphology was observed on the TIP. HA concentration was determined by spectrophotometry at a wavelength of 254 nm using a calibration curve. The effect of some parameters such as pH, additional oxidizer, initial concentration of HA, and light intensity were investigated. Results showed that TIP could degrade a significant amount of HA in a relatively long time. The best result obtained from the experiment was a 98% degradation gained at an initial concentration of 2 mg/L of HA, under the initial condition of pH = 4 and 20 mg/L of H2O2 in 120 min. TIP can be a practical way to degrade HA from water. (C) 2017 Elsevier B.V. All rights reserved.