water Article Hybrid Beads of Zero Valent Iron Oxide Nanoparticles and Chitosan for Removal of Arsenic in Contaminated Water Mian Fawaz Ahmed 1 , Muhammad Asad Abbas 1 , Azhar Mahmood 2 , Nasir M. Ahmad 1, *, Hifza Rasheed 3 , Muhammad Abdul Qadir 4 , Asad Ullah Khan 5 , Hazim Qiblawey 6 , Shenmin Zhu 7 , Rehan Sadiq 8 and Niaz Ali Khan 9,10, *   Citation: Ahmed, M.F.; Abbas, M.A.; Mahmood, A.; Ahmad, N.M.; Rasheed, H.; Qadir, M.A.; Khan, A.U.; Qiblawey, H.; Zhu, S.; Sadiq, R.; et al. Hybrid Beads of Zero Valent Iron Oxide Nanoparticles and Chitosan for Removal of Arsenic in Contaminated Water. Water 2021, 13, 2876. https:// doi.org/10.3390/w13202876 Academic Editor: Antonio Panico Received: 28 July 2021 Accepted: 15 September 2021 Published: 14 October 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 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/). 1 Polymer Research Lab, School of Chemical and Material Engineering, National University of Sciences and Technology (NUST), Islamabad 44000, Pakistan; mianfawaz@gmail.com (M.F.A.); engr.ma.abbas@live.com (M.A.A.) 2 School of Natural Sciences, National University of Sciences and Technology (NUST), Islamabad 44000, Pakistan; dr.azhar@sns.nust.edu.pk 3 National Water Quality Laboratory, Pakistan Council of Research in Water Resources, Islamabad 44000, Pakistan; pcrwr2005@yahoo.com 4 The Institute of Chemistry, University of the Punjab, Quaid-e-Azam Campus, Lahore 54770, Pakistan; mabdulqadir.chem@pu.edu.pk 5 Department of Chemical Engineering, COMSATS University Islamabad, Lahore Campus, Lahore 54000, Pakistan; asadkhan@cuilahore.edu.pk 6 Department of Chemical Engineering, College of Engineering, Qatar University, Doha P.O. Box 2713, Qatar; hazim@qu.edu.qa 7 State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China; smzhu@sjtu.edu.cn 8 Faculty of Applied Sciences, School of Engineering, University of British Colombia, Okanagan Campus, Kelowna, BC V1V 1V7, Canada; rehan.sadiq@ubc.ca 9 School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China 10 Nova Materials Technologies, Lahore 54900, Pakistan * Correspondence: nasir.ahmad@scme.nust.edu.pk (N.M.A.); niaz@tju.edu.cn (N.A.K.) Abstract: Water contaminated with highly hazardous metals including arsenic (As) is one of the major challenges faced by mankind in the present day. To address this pressing issue, hybrid beads were synthesized with various concentrations of zero valent iron oxide nanoparticles, i.e., 20% (FeCh-20), 40% (FeCh-40) and 60% (FeCh-60) impregnated into a polymer of chitosan. These hybrid beads were employed as an adsorbent under the optimized conditions of pH and time to facilitate the efficient removal of hazardous arsenic by adsorption cum reduction processes. X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Brunauer- Emmett-Teller BET, a porosity test and wettability analysis were performed to characterize these hybrid beads. The porosity and contact angle of the prepared hybrid beads decreased with an increase in nanoparticle concentration. The effects of various adsorption factors such as adsorbent composition, contact period, pH value and the initial adsorbate concentration were also evaluated to study the performance of these beads for arsenic treatment in contaminated water. FeCh-20, FeCh-40 and FeCh-60 have demonstrated 63%, 81% and 70% removal of arsenic at optimized conditions of pH 7.4 in 10 h, respectively. Higher adsorption of arsenic by FeCh-40 is attributed to its optimal porosity, hydrophilicity and the presence of appropriate nanoparticle contents. The Langmuir adsorption kinetics described the pseudo second order. Thus, the novel beads of FeCh-40 developed in this work are a potent candidate for the treatment of polluted water contaminated with highly toxic arsenic metals. Keywords: zero valent iron oxide; chitosan; nanoparticles; arsenic; adsorption; isotherm model; kinetics Water 2021, 13, 2876. https://doi.org/10.3390/w13202876 https://www.mdpi.com/journal/water