Decades later, the development of industrialization has gained strength in society; nevertheless, it has also caused negative environmental impacts on ecosystems. It is mentioned that about 15% of dyes are discarded incorrectly in the environment, especially in aquatic environments, which generates risks for both nature and health [1, 2]. Numerous dyes, including methylene blue [3] (phenothiazine dyes) and indigo carmine, among others, contain aromatic rings; therefore, biodegradation is not feasible [4, 5].
"Emerging contaminants” that are distributed in all ecosystems in low concentrations. In this group of contaminants, drugs [6], there are compounds from the group (metoprolol, propranolol, atenolol, and pindolol) among others. They are characteristic compounds of the multi-functionalized aromatic group, soluble in water, and susceptible to deionization [7–9]. In European wastewater, an average concentration of 0.01 µg∙L− 1 has been quantified up to concentrations of 0.29 to 0.01 µg∙L− 1 in research effluents [10]. Many of the drugs are designed to be consumed orally, as they are resistant to neutral and/or basic hydrolysis, oxidation, or photolysis, which become their main routes of abiotic dissipation in natural waters. In relation to this, propranolol has a naphthalene skeleton, which indicates that it can act as a photosensitizing agent and be unstable to light [11].
Propranolol hydrochloride (PPH) is a non-selective β-blocker for clinical use, mainly acting in cardiovascular therapy [12, 13] and for the management of primary hypertension [14]. The assertion that the decrease in blood pressure is a consequence of diminished cardiac output due to the inhibition of beta-receptors in the heart is subject to criticism [15]. The presence of PPH in water [16] of concern due to its potential adverse effects on aquatic organisms and aquatic ecosystems in general. Although PPH is a commonly prescribed beta-blocker it has been considered relatively safe for humans [17], when used correctly. It can have adverse effects on aquatic organisms, especially at concentrations higher than those found in drinking water.
Industrial dyeing generates effluents, which comprise organic contaminants, and require treatment prior to discharge into natural water sources. Contemporary methods for treating wastewater involve the utilization of specialized oxidation techniques, including ozonation, Fenton reactions, and photocatalysis [18–20]. Considerable interest has been directed towards photocatalysis due to its potential to eliminate toxic inorganic compounds, heavy metals, and organic pollutants from wastewater in the sense of a sustainable, eco-friendly, and straightforward method [21–23].
Solutions to technological and environmental challenges in the fields of solar energy conversion, catalysis, medicine, and water remediation are offered by nanomaterials [24, 25]. Researchers utilize metal oxide nanomaterials, including Fe3O4, TiO2, Al2O3, CuO, ZnO, and MgO, due to their versatile physical, chemical, and morphological properties that can be customized for specific uses while manipulating the parameters of synthesis [26–28]. Photodegradation of pollutants in water is a process in which reactive oxygen species are produced [27].
Conventional methods such as reverse osmosis, hydrogen peroxide treatment, dialysis, and UV photocatalysis [29] are used to deplete the pollutants from the water. Therefore, emphasis will be placed on UV photocatalysis because it is an effective method, easy to access, simple in design, and the degradation of wastewater is complete. The use of nanomaterials of a metal oxide nature has the properties of disintegrating dyes from dye effluents. An oxidation process has been developed under ultraviolet light using low molecular weight metal oxide nanomaterials, giving CO2, H2O and aliphatic acid as final products. Scientists have discovered significant interest in creating inorganic nanomaterials, such as metal oxide, metal tungstate, and metal molybdates, through synthesis [29, 30].
Copper tungstate (CuWO4) is part of the tungstate family of divalent transition metals structurally related to each other. These compounds have 3d orbitals, thus being responsible for the electronic correlation effects [30]. This semiconductor material with high catalytic capacity, applied to nitric oxide gas sensors [31, 32], photoelectrochemical water splitting [33–35]. CuWO4 has the property of absorbing indirectly, and these fine particles are devoid of d-d transition forces; they are generally observed at wavelengths of 600 nm in CuWO4 powder since the thickness is 200 nm [36], Its potential as an element for use in different strategic areas is attributed to the most suitable properties of CuWO4 and its narrow band-gap energy (∼2.2 eV), which makes CuWO4 function as an active visible light photocatalyst structure [37–39]. Recent research implies that CuWO4 nanoparticles have greater photocatalytic activity in relation to P25 [30]. The formation of CuWO4 occurs through the reaction of Cu2+ with WO3 at high temperatures to generate the product [40], which is possible to produce in the form of thin particles with the controlled addition of Cu2+ on the WO3 substrate [41].
The present study aims to understand in detail the reduction of PPH, AA, AB, and IC in the presence of green photocatalyst [37] the metal oxide CuWO4 through the use of UV light. The analytical techniques UV-Visible Absorption Spectroscopy and HPLC are used, and their kinetic studies are displayed. The heterogeneous characteristics of the catalyst facilitate its subsequent removal following its utilization [42].