Removal of Humic Acid From Aqueous Solutions Using Ultraviolet Irradiation Coupled With Hydrogen Peroxide and Zinc Oxide Nanoparticles Publisher



Nazmara S^{1, 2} ; Oskoei V¹ ; Zahedi A¹ ; Rezanasab M³ ; Shiri L¹ ; Fallahizadeh S^{4, 5} ; Vahidikolur R⁶
Source: International Journal of Environmental Analytical Chemistry Published:2022

Abstract

In this study, individual performance of ultraviolet irradiation (UV), zinc oxide nanoparticles (ZnO) and hydrogen peroxide (H2O2) processes, as well as a performance of combined processes of UV/H2O2 and UV/H2O2/ZnO, were assessed for the removal of humic acid (HA) from aqueous solutions. Various process-related factors, such as the concentration of ZnO (0.2 and 0.5 g/L), the concentration of H2O2 (20, 30 and 50 mg/L), UV = 125 W, pH (4, 7 and 10), initial HA concentrations (at wavelength of 254 nm) of 2, 5, 7 and 10 mg/L, and three types of interferences (nitrate, sulphate and chloride) were studied and optimised. The results showed that removal efficiency decreased by increasing the concentration of HA and pH values in all processes, but it increased by increasing the time of exposure and the concentration of H2O2. In the combined process of UV/ZnO/H2O2, the nanoparticle concentration of 0.2 g/L yielded the highest efficiency, whereas in the other processes, the highest efficiency was observed at nanoparticle concentration of 0.5 g/L. Based on these results, under the optimum conditions (HA = 2 mg/L, H2O2 = 50 mg/L, ZnO = 0.2 g/L, pH = 4.0 and contact time of 15 min), UV/ZnO/H2O2 process was found as the most efficient combination in removing of HA with an efficiency of 99.99%. Furthermore, the modelling results indicated that the adsorption reaction of HA onto ZnO nanoparticles was very well described by the pseudo-second-order kinetic model (R 2 > 0.99). © 2020 Informa UK Limited, trading as Taylor & Francis Group.