Magnetic chitosan composite for adsorption of cationic and anionic dyes in aqueous solution Dong-Wan Cho a , Byong-Hun Jeon b, *, Chul-Min Chon c , Franklin W. Schwartz d , Yoojin Jeong a , Hocheol Song a, ** a Department of Environment and Energy, Sejong University, Seoul 143-747, South Korea b Department of Natural Resources and Environmental Engineering, Hanyang University, 2226 Wangsimni-ro, Seongdong-gu, Seoul 133-791, South Korea c Geologic Environment Division, Korea Institute of Geoscience and Mineral Resources, Daejeon 305-350, South Korea d School of Earth Sciences, The Ohio State University, Columbia, OH 43210, USA Introduction Many industries such as textile, leather, food processing, dyeing, and cosmetics generate massive amount of wastewater, and dye chemicals represent one of the most prominent contaminants contained in the wastewater effluents [1]. Surface- and ground- waters contaminated with dyes are easily recognizable due to their high colorant visibility even in very small quantities. The presence of dye in the water bodies increases the chemical oxygen demand as well as adversely influences the metabolic functions of phytoplank- ton and aquatic plants by interfering with photosynthesis [2]. Industrial wastewater treatments largely depend on microbial- mediated treatments processes, but they occasionally suffer from limited efficiencies in dyes removal due to low biodegradability of dye materials, and inhibition effect of high salt concentration of wastewaters [3]. Alternatively, numerous technologies have been applied to control dye contamination, including adsorption [4,5], oxidation [6,7], membrane [8], biological treatment [9], and electro-coagulation [10]. Ozone-assisted chemical oxidation has been successfully applied for dyes removal without causing sludge production, but it suffers from short lifetime of ozone and high operation cost [11]. Oxidation utilizing Fenton’s reagent is also shown to be effective in decolorizing both soluble and insoluble dyes, but it generates excessive amounts of sludge during the process [12]. Membrane filtration has disadvantages such as high capital cost and frequent pore clogging. Adsorption method, despite its problems associated with adsorbent disposal and post- contamination by used adsorbents, is considered to be an effective and simple method relatively free from concerns of generating unwanted byproducts, and many recent investigations have focused on the development of low cost and high efficient adsorbents to treat dyes [13–15]. Recently, chitosan-based adsorbents have attracted particular interests due to their environmental-friendly properties, high availability and versatility as a treatment medium [16,17]. Chitosan is a polymeric substance derived from deacetylation of chitin, a major component of skeletons of crustaceans. It has a large number of hydroxyl and amino groups branched from polymeric backbones that are held tight by hydrogen bonding by those functional groups. The amino groups undergo protonation reaction Journal of Industrial and Engineering Chemistry xxx (2015) xxx–xxx A R T I C L E I N F O Article history: Received 24 December 2014 Received in revised form 6 January 2015 Accepted 31 January 2015 Available online xxx Keywords: Methylene blue Methyl orange Chitosan Clay Magnetite A B S T R A C T A magnetic composite material composed of nano-magnetite (NMT), heulandite (HE), and cross-linked chitosan was prepared and used as an adsorbent for methylene blue (MB) and methyl orange (MO). The composite was characterized for the morphology, magnetic and surface properties. The optimal mass ratio of chitosan:HE:NMT for the best removal of both dyes was determined to be 1:1:0.33. The adsorption of MB and MO followed the pseudo-second order kinetics, and the maximum adsorption capacities were 45.1 and 149.2 mg g 1 at pH 5.5, respectively. The adsorption of MB increased with the pH increase, while MO adsorption showed an opposite trend. ß 2015 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved. * Corresponding author. Tel.: +82 2 2220 2242; fax: +82 2 2281 7769. ** Corresponding author. Tel.: +82 2 3408 3232; fax: +82 2 3408 4320. E-mail addresses: bhjeon@hanyang.ac.kr (B.-H. Jeon), hcsong@sejong.ac.kr (H. Song). G Model JIEC-2403; No. of Pages 7 Please cite this article in press as: D.-W. Cho, et al., J. Ind. Eng. Chem. (2015), http://dx.doi.org/10.1016/j.jiec.2015.01.023 Contents lists available at ScienceDirect Journal of Industrial and Engineering Chemistry jou r n al h o mep ag e: w ww .elsevier .co m /loc ate/jiec http://dx.doi.org/10.1016/j.jiec.2015.01.023 1226-086X/ß 2015 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.