  Citation: ˙ Zylla, R.; Foszpa ´ nczyk, M.; Kami ´ nska, I.; Kudzin, M.; Balcerzak, J.; Ledakowicz, S. Impact of Polymer Membrane Properties on the Removal of Pharmaceuticals. Membranes 2022, 12, 150. https:// doi.org/10.3390/membranes12020150 Academic Editors: Wolfgang Samhaber and Mohammad Rezaei Received: 11 November 2021 Accepted: 17 January 2022 Published: 26 January 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 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/). membranes Article Impact of Polymer Membrane Properties on the Removal of Pharmaceuticals Renata ˙ Zylla 1, * , Magdalena Foszpa ´ nczyk 1 , Irena Kami ´ nska 1 , Marcin Kudzin 1 , Jacek Balcerzak 2 and Stanislaw Ledakowicz 3 1 Lukasiewicz Research Network-Textile Research Institute, ul. Brzezi´ nska 5/15, 92-103 Lód´ z, Poland; magdalena.foszpanczyk@iw.lukasiewicz.gov.pl (M.F.); irena.kaminska@iw.lukasiewicz.gov.pl (I.K.); marcin.kudzin@iw.lukasiewicz.gov.pl (M.K.) 2 Department of Molecular Engineering, Faculty of Process and Environmental Engineering, Lodz University of Technology, Wólcza ´ nska 213, 93-005 Lód´ z, Poland; jacek.balcerzak@p.lodz.pl 3 Department of Bioprocess Engineering, Faculty of Process and Environmental Engineering, Lodz University of Technology, ul. Wólcza ´ nska 213, 93-005 Lód´ z, Poland; stanislaw.ledakowicz@p.lodz.pl * Correspondence: renata.zylla@iw.lukasiewicz.gov.pl Abstract: The influence of various factors on the removal efficiency of selected pharmaceuticals by membrane filtration was investigated. Several commercial polymer membranes were used for nanofiltration (NF) from various manufacturers. The studies were conducted for ibuprofen (IBF), amoxicillin (AMX), diclofenac (DCF), tetracycline (TRC), salicylic acid (SA) and acetylsalicylic acid (ASA). The influence of the structure and properties of the tested compounds on the retention coefficient and filtration rate was investigated. The influence of pH on the filtration parameters was also checked. The properties of selected membranes influencing the retention of pharmaceuticals and filtrate flux were analysed. An extensive analysis of the retention coefficients dependence on the contact angle and surface free energy was performed. It was found that there is a correlation between the hydrophilicity of the membrane and the effectiveness and efficiency of the membrane. As the contact angle of membrane increased, the flow rate of the filtrate stream increased, while the retention coefficient decreased. The studies showed that the best separation efficiency was achieved for compounds with a molecular weight (MW) greater than 300 g/mol. During the filtration of pharmaceuticals with MW ranging from 300 to 450 g/mol, the type of membrane used practically did not affect the filtration efficiency and a high degree of retention was achieved. In the case of low MW molecules (SA and ASA), a significant decrease in the separation efficiency during the process was noted. Keywords: nanofiltration; pharmaceuticals; hazardous materials; membrane filtration; amoxicillin; diclofenac; ibuprofen; tetracycline; salicylic acid; acetylsalicylic acid 1. Introduction The subject of wastewater treatment and water recovery is constantly facing new challenges. The development of analytical methods enabled the identification of new threats resulting from the presence of trace amounts of hazardous substances in the natural environment due to human activity. Such substances include pharmaceuticals and hor- mones. Concerns about the presence of pharmaceutically active compounds in drinking water and surface waters have been increasing since the late 1990s [1–4] The constantly increasing demand for pharmaceuticals and their consumption, combined with incomplete metabolism in the human body, have led to an increase in concentration in wastewater and surface waters to which they are discharged. Research conducted around the world shows a fairly common presence of pharmaceuticals in surface waters as well as in wastew- ater and sludge [3–8].Their concentration in tested water samples ranges from ng/dm 3 to μg/dm 3 and it is predicted that with the growing human population and the greater Membranes 2022, 12, 150. https://doi.org/10.3390/membranes12020150 https://www.mdpi.com/journal/membranes