Citation: Manzoor, S.; Garcia, J.F.; Shah, K.H.; Khan, M.I.; Abbas, N.; Raza, H.; Mubarik, S.; Hayat, M.; Iram, A.; Yar, A.; et al. Multipollutant Abatement through Visible Photocatalytic System. Catalysts 2023, 13, 65. https://doi.org/10.3390/ catal13010065 Academic Editor: Lucie Obalová Received: 27 October 2022 Revised: 12 December 2022 Accepted: 15 December 2022 Published: 29 December 2022 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/). catalysts Article Multipollutant Abatement through Visible Photocatalytic System Suryyia Manzoor 1 , Javier Fernandez Garcia 2,3, *, Kausar Hussain Shah 4 , Muhammad Imran Khan 5, * , Naseem Abbas 1, *, Hina Raza 6 , Shamroza Mubarik 7 , Muhamad Hayat 1 , Alveena Iram 1 , Ahmed Yar 1 and Abdallah Shanableh 5 1 Institute of Chemical Sciences, Bahauddin Zakariya University, Multan 60800, Pakistan 2 Department of Chemical Engineering, University College London, Torrington Place, London WC1E 7JE, UK 3 QS School of Engineering, Universitat Ramon Llull, Via Augusta 390, 08017 Barcelona, Spain 4 Institute of Botany, Bahauddin Zakariya University, Multan 60800, Pakistan 5 Research Institute of Sciences and Engineering (RISE), University of Sharjah, Sharjah 272722, United Arab Emirates 6 Faculty of Pharmacy, Bahauddin Zakariya University, Multan 60800, Pakistan 7 Department of Chemistry, Government Sadiq College Women University, Bahawalpur 63100, Pakistan * Correspondence: javier.fernandez@iqs.url.edu (J.F.G.); raoimranishaq@gmail.com (M.I.K.); dr.naseem.abbas@gmail.com (N.A.) Abstract: Water pollution damages the aquatic environment due to the presence of organic con- taminants, which in turn is distressing to the ecosystem. Photocatalytic activity is a greener and promising method to degrade these organic contaminants. In this research, we present the degra- dation of diverse water pollutants through zinc/iron oxide nanoparticles serving as photocatalysts. The photocatalyst was studied for its efficiency to photodegrade congo red, brilliant green and para nitro phenol. Moreover, it also presented an antibacterial activity against the bacterium E. coli. Pho- tocatalyst was characterized via X-ray diffraction, scanning electron microscopy-energy dispersive X-ray spectroscopy, and fourier-transform infrared spectroscopy. Tauc plot was used to measure the optical band gap (1.84 eV). The effect of various parameters such as catalyst dose, contact time, dye dose/concentration and pH were also investigated to determine the optimum point of maxi- mum degradation through response surface methodology. A face-centered composite design was used, and a quadratic model was followed by congo red, brilliant green dyes and para nitrophenol. The maximum photodegradation efficiencies were 99%, 94.3%, and 78.5% for congo red, brilliant green and phenol, respectively. Quantum yield for congo red, brilliant green and para-nitrophenol were 9.62 × 10 −8 , 1.17 × 10 −7 and 4.11 × 10 −7 molecules/photons, while the reaction rates were 27.1 μmolg −1 h −1 , 29.61 μmolg −1 h −1 and 231 μmolg −1 h −1 , respectively. Keywords: photodegradation; congo red; brilliant green; para-nitrophenol; antibacterial activity; E. coli 1. Introduction The vital explanation for environmental pollution is industrialization in developing countries. In recent years, the requirement for human needs has increased dramatically, with a higher demand for a variety of chemical products that could be used in industries and can cause environmental pollution. In water, some of these chemicals like synthetic dyes, phenols, etc., usually exhibit a reduction reaction, leading to the development of mutagenic compounds or carcinogenic products that threaten the sustainability of aquatic life, the ecosystem, and microorganisms. In addition, this polluted water impacts the human body’s immune system, central nervous, respiratory system, eye skin irritation, and lung edema [1]. Due to this, the availability of clean water has become a critical issue, especially in underdeveloped countries. To abate these organic contaminants, various chemicals, Catalysts 2023, 13, 65. https://doi.org/10.3390/catal13010065 https://www.mdpi.com/journal/catalysts