Removal of humic acid from aqueous solution using UV/ZnO nano-photocatalysis and adsorption

Humic acid is a natural organic material produced as a result of biological and geochemical reactions and it is one of the main precursor materials of disinfection by-products. The rapid removal and fast adsorption of humic add using zinc oxide nanoparticle irradiated by the ultraviolet light (ZnO/UV) were well elucidated and investigated. The impact of various influential factors such as ZnO dosage, initial humic add concentration, reaction time and pH on the adsorption capacity and removal of humic acid was well studied and optimized. The optimization study confirms that an increase in the initial concentration of humic acid and the pH of the environment decreased the removal efficiency while increase in the time of irradiation increased the removal efficiency. The maximum removal efficiency of humic acid for the single-stage process was found to be 0.2 g/l ZnO and for that of two-stage process was found to be 0.5 g/l ZnO. The obtained results reveal that the two-stage photocatalysis was the most preferable method for the humic add removal and it results in more than 98.95% of humic add within only 30 min of photocatalysis. (C) 2015 Elsevier B.V. All rights reserved.