Citation: Despotovi´ c, V.; Finˇ cur, N.; Bognar, S.; Šoji´ c Merkulov, D.; Putnik, P.; Abramovi´ c, B.; Pani´ c, S. Characterization and Photocatalytic Performance of Newly Synthesized ZnO Nanoparticles for Environmental Organic Pollutants Removal from Water System. Separations 2023, 10, 258. https:// doi.org/10.3390/separations10040258 Academic Editor: Gavino Sanna Received: 15 March 2023 Revised: 7 April 2023 Accepted: 14 April 2023 Published: 16 April 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/). separations Article Characterization and Photocatalytic Performance of Newly Synthesized ZnO Nanoparticles for Environmental Organic Pollutants Removal from Water System Vesna Despotovi´ c 1,† , Nina Finˇ cur 1,† , Sabolˇ c Bognar 1 , Daniela Šoji´ c Merkulov 1, * , Predrag Putnik 2, * , Biljana Abramovi´ c 1 and Sanja Pani´ c 3 1 Department of Chemistry, Biochemistry and Environmental Protection, University of Novi Sad Faculty of Sciences, Trg Dositeja Obradovi´ ca 3, 21000 Novi Sad, Serbia; vesna.despotovic@dh.uns.ac.rs (V.D.); nina.fincur@dh.uns.ac.rs (N.F.); sabolc.bognar@dh.uns.ac.rs (S.B.); biljana.abramovic@dh.uns.ac.rs (B.A.) 2 Department of Food Technology, University North, Trg dr. Žarka Dolinara 1, 48000 Koprivnica, Croatia 3 Faculty of Technology, University of Novi Sad, Bulevar cara Lazara 1, 21000 Novi Sad, Serbia; sanjar@tf.uns.ac.rs * Correspondence: daniela.sojic@dh.uns.ac.rs (D.Š.M.); pputnik@alumni.uconn.edu (P.P.) † These authors contributed equally to this work. Abstract: Most countries are facing problems of environmental pollution due to toxic organic pol- lutants being discharged into the environment from various man-made sources. Heterogeneous photocatalysis is a possible solution for the mentioned problem, and it has been widely applied for the removal of pollutants from aqueous solutions, thanks to its high removal efficiency and environmental friendliness. Among the commonly used metal oxides, ZnO has attracted researchers’ interests due to its ecofriendly and nontoxic nature. In this work, ZnO nanoparticles (ZnO-NPs) were prepared by the precipitation method from water (w) and ethanol solutions of the corresponding metal precursors (zinc–acetate dihydrate, A_ZnO, and zinc–nitrate hexahydrate, N_ZnO) followed by calcination at different temperatures. The structure and morphology of the prepared catalysts were characterized by different techniques (XRD, BET, and SEM). Based on the XRD results, it can be seen that the synthesized NPs possess high purity. Furthermore, at a higher calcination temperature, a higher crystal size was observed, which was more intense in the case of the ethanol solution of the precursors. The BET analysis showed macropores at the surface and also indicated that the increased temperature led to decreased surface area. Finally, SEM images showed that in the case of the water precursor solution, an irregular, rod-like shape of the NPs was observed. The photocatalytic properties of newly synthesized ZnO-NPs exposed to simulated sunlight were examined during the removal of pesticide clomazone (CLO) and the antidepressant drug amitriptyline (AMI). ZnO-NPs prepared by the precipitation method from the water solution of zinc–acetate dihydrate and calcined at 500 ◦ C (A_ZnOw_500) showed the highest performance under simulated sunlight. Furthermore, the activity of A_ZnOw_500 and N_ZnOw_500 catalysts in the removal of three organic pollutants from water—two pesticides (sulcotrione (SUL) and CLO) and one pharmaceutical (AMI)—was also compared. Results showed that decreased photocatalytic activity was observed in the presence of N_ZnOw_500 NPs in all investigated systems. Finally, the effect of the initial pH was also examined. It was found that in the case of CLO and SUL, there was no influence of the initial pH, while in the case of AMI the k app was slightly increased in the range from pH ~7 to pH ~10. Keywords: ZnO; chemical precipitation; metal precursors; removal efficiency; pesticides; pharmaceuticals 1. Introduction The release of pollutants, such as pesticides and pharmaceutically active compounds, in the environment is a global concern and has attracted much attention from the public and the scientific community, due to their adverse impact on human health, plants, soil, Separations 2023, 10, 258. https://doi.org/10.3390/separations10040258 https://www.mdpi.com/journal/separations