Evaluation of Sonocatalytic and Photocatalytic Processes Efficiency for Degradation of Humic Compounds Using Synthesized Transition-Metal-Doped ZnO Nanoparticles in Aqueous Solution

Cláudia G Silva,Nader Marzban,Afshin Maleki,Mehran Seifi

doi:10.1155/2021/9938579

Abstract

The existence of a humic substance in water causes the growth of microorganisms and reduces the quality of water; therefore, the removal of these materials is crucial. Here, the ZnO nanoparticles doped using transition metals, copper (Cu) and manganese (Mn), were used as an effective catalyst for photocatalytic removal of humic substances in an aqueous environment under ultraviolet, visible light, and light-emitting diode irradiations. Also, we study the effect of the sonocatalytic method. A solvothermal procedure is used for doping, and the Cu- and Mn-doped ZnO nanocatalyst were characterized by means of FTIR, XRD, AFM, SEM, and EDAX analyses. We investigate the effect of operational variables, including doping ratio, initial pH, catalyst dose, initial HS content, and illuminance on the removal efficiency of the processes. The findings of the analyses used for the characterization of the nanoparticles illustrate the appropriate synthesis of the Cu- and Mn-doped ZnO nanocatalysts. We observe the highest removal efficiency rate under acidic conditions and the process efficiency decreased with increasing solution pH, when we tested it in the range of 3–7. Photocatalytic decomposition of HS increases with a rise in catalyst dose, but an increase in initial HS content results in decreasing the removal efficiency. We observe the highest photocatalytic degradation of humic acid while using the visible light, and the highest removal efficiency is obtained using Cu.ZnO. The Cu.ZnO also shows better performance under ultraviolet irradiation compared to other agents.

Highlights

Degradation of plants and animals by microorganisms in water can mainly result in humic substances (HSs), which are the major part of natural organic matters (NOMs) [1,2,3].ese materials can decline the quality of drinking water as they cause color, taste, and odor [4]
The results reported by Subash et al showed that the synthesized Ce codoped Ag–ZnO photocatalyst could effectively degrade Naphthol Blue Black (NBB) dye under natural sunlight illumination [28]. e application of ultrasonic irradiation generates microjets stemming from the collapse of cavitation bubbles in the solution; this causes the solution to be stirred well
Humic acids (HAs) as the target pollutant as well as an important chemical compound which is a pervasive substance in the environment, a natural refractory organic matter, and an important carcinogenic precursor in water supply was considered in this study and the efficiency of synthesized doped nanoparticles including ZnO, Cu.ZnO, Mn.ZnO, and Cu.Mn.ZnO in its catalytic degradation under ultraviolet irradiation, ultrasound radiation, light-emitting diode (LED), and visible light illumination was determined and evaluated. e effect of dopants concentration, solution pH, catalyst dosage, initial HAs concentration, and contact time on the degradation process of HAs and optical properties of nanoparticles was investigated

Summary

Research Article

Evaluation of Sonocatalytic and Photocatalytic Processes Efficiency for Degradation of Humic Compounds Using Synthesized Transition-Metal-Doped ZnO Nanoparticles in Aqueous Solution. The ZnO nanoparticles doped using transition metals, copper (Cu) and manganese (Mn), were used as an effective catalyst for photocatalytic removal of humic substances in an aqueous environment under ultraviolet, visible light, and light-emitting diode irradiations. We investigate the effect of operational variables, including doping ratio, initial pH, catalyst dose, initial HS content, and illuminance on the removal efficiency of the processes. Photocatalytic decomposition of HS increases with a rise in catalyst dose, but an increase in initial HS content results in decreasing the removal efficiency. We observe the highest photocatalytic degradation of humic acid while using the visible light, and the highest removal efficiency is obtained using Cu.ZnO. We observe the highest photocatalytic degradation of humic acid while using the visible light, and the highest removal efficiency is obtained using Cu.ZnO. e Cu.ZnO shows better performance under ultraviolet irradiation compared to other agents

Introduction

Materials and Methods

Results and Discussion

ZnKα CuKβ

Type of process

Watt LED lamp

Visible light