Copolymerehydrous zirconium oxide hybrid microspheres for arsenic sorption Bryan Moraga a , Leandro Toledo a , Lud  ek Jelínek b , Jorge Ya ~ nez c , Bernab  e L. Rivas a , Bruno F. Urbano a, * a Departamento de Polímeros, Facultad de Ciencias Químicas, Universidad de Concepci on, Concepci on, Chile b Department of Power Engineering, University of Chemistry and Technology, Prague, Czech Republic c Departmento de Quimica Analítica e Inorg anica, Facultad de Ciencias Químicas, Universidad de Concepci on, Concepci on, Chile article info Article history: Received 22 April 2019 Received in revised form 30 August 2019 Accepted 2 September 2019 Available online 10 September 2019 Keywords: Arsenic Hybrid Adsorbent Zirconium abstract In this work, a hybrid organic-inorganic adsorbent based on polyelectrolyte copolymers of poly(4- vinylbenzyl trimethylammonium chlorideecoe2-hydroxyethyl methacrylate) microspheres mixed with a hydrous zirconium oxide phase were applied to remove arsenic species from aqueous solutions. The hybrid adsorbent was synthesized in a two-step procedure: first, the polymeric microspheres were obtained through emulsion radical copolymerization, and then, the microspheres were impregnated with a zirconium oxide precursor followed by the subsequent sol-gel reaction. The purpose of this hybrid material was to combine properties of each component in the interaction with arsenic oxoanions and compare its performance with commercial adsorbents. The polymer hybrid microspheres were shown to remove arsenate, and the presence of the inorganic phase also allowed for the removal of arsenite. The hybrid adsorbent exhibited arsenic sorption independent of pH, is able to regenerate, displays fast ki- netics and has the ability to reduce arsenic concentration in treated water below 10 mgL 1 even in real samples with an initial concentration as high as 380 mgL 1 . © 2019 Elsevier Ltd. All rights reserved. 1. Introduction Groundwater constitutes 97% of the world's fresh water and provides water to rivers during periods without rain. Millions of people depend directly on drinking water aquifers, and 40% of the world's food is produced by irrigated agriculture, which depends on groundwater. Various organic and inorganic contaminants are present in water sources used for human consumption, with arsenic (organic and inorganic) being one with the highest toxicity. Exposure to high levels of arsenic can result in severe damage to health, causing cardiovascular diseases, diabetes and cancer of the skin, tongue, lung and gallbladder, among others(Bissen and Frimmel, 2003; Kenyon and Hughes, 2001; Valko et al., 2005). Arsenic contamination is a concern around the world. In some countries, such as China, Tibet, Mongolia, India, Bangladesh, Viet- nam, Cambodia, Thailand, Taiwan, Argentina, Chile and Mexico, a large portion of the water is contaminated with arsenic in levels from 100 to more than 2000 mgL 1 . This situation is especially se- vere in West Bengal (India) and Bangladesh, where the concen- tration is within the range of 10e196 mg L 1 and 9.0e28 mg L 1 , respectively. It has been estimated that a population of more than 100 million people is exposed to drinking groundwater with arsenic concentrations higher than 50 mgL 1 . In Chile, it has been observed that the highest occurrence of arsenic is between the parallels 17  30 0 and 26  05 0 south latitude and between the west longitude 67  00 0 and the Pacific Ocean, including the cities Anto- fagasta, Calama, Santiago, Rancagua, Taltal, Tocopilla and San Pedro de Atacama, with the highest exposure to this metalloid in con- centrations as high as 1000 mgL 1 (Silva-Pinto et al., 2010). To reduce the risk to human health, the Environmental Protection Agency (EPA) of the United States and the World Health Organi- zation (WHO) implemented a standard of arsenic in drinking water, reducing the level allowed from 50 mgL 1 to 10 mgL 1 (WHO, 2004). The strategies or methods for arsenic removal are diverse; however, only a few have reached practical application. For example, oxidation/precipitation-filtration (Zheng et al., 2004), coagulation/flocculation (Bilici Baskan and Pala, 2010), adsorption (Goh et al., 2008; Huang et al., 2014) and membrane * Corresponding author. E-mail address: burbano@udec.cl (B.F. Urbano). Contents lists available at ScienceDirect Water Research journal homepage: www.elsevier.com/locate/watres https://doi.org/10.1016/j.watres.2019.115044 0043-1354/© 2019 Elsevier Ltd. All rights reserved. Water Research 166 (2019) 115044