**1. Introduction**

In recent years, the concentrations of toxic pharmaceutical products in the global environment have increased substantially [1,2]. Pharmaceutical and chemical personal care products are widely used in daily life. Unfortunately, more than 50% of these hazardous products are discharged into the environment, such as in rivers, which can cause danger to fauna and flora [3]. Therefore, their destruction of ecological processes and functions in freshwater ecosystems is often called to be limited or reduced, as the continuous input of these pharmaceutical molecules in the water environment affects water safety, resulting in chronic toxic effects on organisms [4–7] and has potential impacts on human health through the food chain [8]. Numerous pharmaceutical products are discharged into the water environment, and atenolol (AT) and propranolol (PR) are the most used medicaments. PR and AT are medications called beta-blockers and are used to treat cardiovascular diseases, such as hypertension, tachycardia, and acute myocardial infarction [9]. In recent research studies, AT and PR were detected at high concentration levels in urban wastewater treatment plant effluents [10–13]. In addition, AT and PR were widely detected in hospital

**Citation:** Samir, B.; Bouazizi, N.; Nkuigue Fotsing, P.; Cosme, J.; Marquis, V.; Dotto, G.L.; Le Derf, F.; Vieillard, J. Preparation and Modification of Activated Carbon for the Removal of Pharmaceutical Compounds via Adsorption and Photodegradation Processes: A Comparative Study. *Appl. Sci.* **2023**, *13*, 8074. https://doi.org/ 10.3390/app13148074

Academic Editors: Amanda Laca Pérez and Yolanda Patiño

Received: 20 May 2023 Revised: 23 June 2023 Accepted: 26 June 2023 Published: 11 July 2023

**Copyright:** © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

sewage and wastewater treatments in concentrations ranging from about 0.78 to 6.6 μg/L in Greece [14]. Regarding the above problems, water quality is in danger, and alternative reserves or crucial solutions are requested to alleviate this issue. Wastewater treatments via biological, filtration, settling, adsorption, coagulation, and many other processes displayed interesting results in removing these toxic products. However, almost all these processes showed a real weakness due to the lack of continuous properties and the high energy consumption. Adsorption is a very useful method for wastewater treatments, representing an eco-friendly and low-cost option. While adsorption is suitable for water treatment, it can only be considered an effective process if the adsorbent has complementary properties that ensure its eco-friendly and high adsorption capacities during its utilization.

Numerous adsorbents have been developed with the above aims, such as metallic oxide, biomass, activated carbon, graphene oxide, metal–organic frameworks, and zeolites [15–19]. To produce eco-friendly and low-cost properties, researchers focused on biomass and its derivatives as potential adsorbents and effective candidates for wastewater treatments. Up to now, activated carbon has been considered one of the best materials for water treatment due to its surface properties, low cost, and high capacity to remove pollutants from water. However, the rapid saturation of these adsorbents means they must be changed or recycled frequently; heterogeneous photocatalysts can be a good alternative to adsorption. This chemical process of photocatalysis involves reactive radical species, such as hydroxyl radicals (HO·), in the presence of a semiconductor catalyst based on a metal oxide to degrade the pharmaceutical molecules. Titanium dioxide (TiO2) is a good catalyst due to its photochemical stability. Lu et al. and many other researchers investigated the immobilization of TiO2 nanoparticles on an activated carbon surface to improve the photocatalytic activity and make the separation of treated effluent more effective [20–23]. The results obtained toward this goal are of great importance and, up to now, have not been developed. The coating of surfaces with TiO2 produces a relatively low improvement regarding the photocatalytic reaction because of the particles' low dispersion and limited mass transfer between the pollutant molecules and the catalyst [24,25]. Catalysts can be more effective and easily separated from the effluent [26–28].

In this regard, activated carbon covered with TiO2 semiconductors is active since it enhances the photocatalytic reaction between TiO2 and the contaminants due to the adsorption of pollutants on its surface [29,30]. Increased adsorption contributes to a higher concentration of contaminants around the TiO2 active sites [31]. Therefore, this study was designed to examine removing AT and GT pharmaceutical products from the water via adsorption and photodegradation with activated carbon and activated carbon covered with TiO2. This first study focused on treating products with environmentally activated carbon and TiO2. The results of this study could be used as a solution for water treatments, which is considered the most important environmental pollution issue to be resolved. In detail, this study evaluated the removal of AT and PR via an adsorption process using agro-waste (date stems) as a source of activated carbon (AC). At first, the adsorption of AT and PR was evaluated on AC and AC-OH, and then, their photodegradation in the presence of a heterogenous photocatalyst (AC-TiO2) was tested.
