Solar Photocatalysis for the Decontamination Of Water from Emerging Pharmaceutical Pollutant Chloroquine Using Nano ZnO as the Catalyst

Abstract

Photo-driven advanced oxidation process (AOP) with pharmaceutical wastewater has been poorly investigated so far. This paper presents the results of an experimental investigation on the photocatalytic degradation of emerging pharmaceutical contaminant chloroquine (CLQ) in water using zinc oxide (ZnO) nanoparticles as the catalyst and solar light (SL) as the source of energy. The catalyst was characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDAX), and transmission electron microscopy (TEM). The effect of various operating parameters such as catalyst loading, the concentration of target substrate, pH, and the effect of oxidants and anions (salts) on the efficiency of degradation was tested. The degradation follows pseudo-first-order kinetics. Surprisingly, contrary to the observation in most photocatalytic studies, the degradation is more efficient under solar radiation, with 77% under solar (SL) irradiation and 65% under UV light in 60 min. The degradation leads to slow and complete COD removal through several intermediates identified by the liquid chromatography–mass spectrometry (LC-MS) technique. The results suggest the possibility of using inexpensive natural, non-renewable solar energy for the purification of CLQ-contaminated water, thereby enabling the reuse of scarce water resources. Graphical Abstract

Copper-Based Two-Dimensional Metal–Organic Frameworks for Fenton-like Photocatalytic Degradation of Methylene Blue under UV and Sunlight Irradiation

“…The initial increase in the degradation efficiency is attributed to the availability of additional active sites for the reaction owing to the higher concentration of the catalyst. However, as the amount of the catalyst increases further, the degradation rate decreases due to the aggregation of catalyst particles, which reduces the accessibility of the active sites for organic pollutants . Furthermore, excess catalysts can hinder light penetration, impeding the effective utilization of UV irradiation and subsequently reducing the degradation efficiency (Figure ).…”

ZnO-based heterojunction catalysts for the photocatalytic degradation of methyl orange dye

“…A key characteristic of advanced oxidation processes (AOPs) is the production of highly reactive hydroxyl radicals, which possess superior oxidative power compared to ozone and hydrogen peroxide. This feature has facilitated the accelerated degradation of organic pollutants [ 12 , 13 ]. Consequently, AOPs have gained prominence and have become preferred alternatives over traditional water treatment methods, due to their remarkable success in effectively degrading organic pollutants [ 14 ].…”

“…Consequently, AOPs have gained prominence and have become preferred alternatives over traditional water treatment methods, due to their remarkable success in effectively degrading organic pollutants [ 14 ]. Among the various AOP methods, photocatalysis and its various adaptations have emerged as the most promising technique for industrial applications [ 13 ]. Semiconductor oxides, particularly ZnO and its nanocomposites, have been extensively investigated and widely employed as catalysts in photocatalysis.…”

Bio-based Au Doping with Dominant Oxygen Vacancies and Ti3+ Defects on Photocatalytic Functionalities of TiO2

“…The charge trapping sites formed help to diffuse highly energetic electrons from the conduction band (CB) into the network structure of metal dopants, which eventually delay e – /h + recombination . Au is a potential dopant due to its high stability and nonreactivity and it could also insert new energy levels by equivalent substitution of Ti (atomic radius 0.147 nm) with Au (atomic radius of 0.147 nm). , Few studies reported on Au doping onto TiO 2 using toxic chemicals of environmental concern. , The bio-based methods are eco-friendly and environmentally benign. It could improve the surface properties and increase the number of defects in metal-doped photocatalysts to enhance their activity.…”