Preparation of chitosan-ethyl acrylate as a biopolymer adsorbent for basic dyes removal from colored solutions Mousa Sadeghi-Kiakhani a , Mokhtar Arami b , Kamaladin Gharanjig a,c, * a Institute for Color Science and Technology, Department of Organic Colorants, Tehran, Iran b Amirkabir University of Technology, Faculty of Textile Engineering, Tehran, Iran c Center of Excellence for Color Science and Technology, Institute for Color Science and Technology, Tehran, Iran Introduction Colored effluents of dyeing units generate a considerable amount of polluted wastewater and will cause considerable damage to the environment if discharged untreated [37,26,15]. During the past decades, several physical and chemical wastewater treatment methods have been used to remove the color from the dye effluents, which varying in usefulness, operating cost, and environmental impact [16,28] (Dutta et al., 2004) [44]. Among all the treatments proposed, adsorption of dye molecules on the adsorbent can be a very suitable and a cost-effective process to remove the color from aqueous solutions [8,13,25,32]. So, studies for obtaining the low cost adsorbents with high adsorption capacities are still under improvement to decrease the adsorbent dosage and reduce the removal difficulties [7,9,4]. Recently, many attentions have been focused on the various bio-sorbents such as fungal, bacterial biomass and biopolymers, which can be achieved in bulky quantities with minimum damaging effects on the nature. In this respect, individual efforts have been carried out onto polysaccharides such as chitosan [23,22]. Chitosan has been investigated by several researchers as a biopolymer adsorbent for the dyes removal from aqueous solutions [31,41,10]. Chitosan, because of its environmentally friendly nature and macromolecular structure with different functional groups, has been found to posses many uniqueness properties that the cause of recent attention in various fields, including biotechnology, water treatment, medicine, membranes, cosmetics, and the food industry (Roller and Covill, 1999) [2,30,45]. The application of chitosan as a biopolymer adsorbent is acceptable thanks to having the two major advantages: firstly, inexpensive compared to commercial adsorbents; secondly, strong chelating ability toward pollutants [10,12,36]. Chitosan has been much potential as an efficient adsorbent for almost all classes of dyes, except basic dyes, that can be related to its natural cationic property [10,5,14,6]. There are a few papers concerning the chemical modification of the chitosan for the removal of basic dyes from colored textile effluents. Lazaridis et al. reported the chemical modifications onto the chitosan by grafting poly (acrylic acid) and poly (acrylamide) through persulfate induced free radical initiated polymerization processes and covalent cross-linking of the prepared materials for elimination Journal of Environmental Chemical Engineering 1 (2013) 406–415 A R T I C L E I N F O Article history: Received 13 March 2013 Accepted 1 June 2013 Keywords: Chitosan Biopolymer adsorbent Basic dyes RSM Dye removal A B S T R A C T In this study, the chitosan-ethyl acrylate (Ch-g-Ea) as a biopolymer adsorbent was prepared and used for the removal of Basic Blue 41 (BB41) and Basic Red 18 (BR18) from colored solutions. The purified product was characterized using FTIR, 1 H NMR and 13 C NMR analyses. The obtained results from spectroscopic data confirmed an acceptable relation with chemical structure of Ch-g-Ea. Response surface methodology (RSM) involving a central composite design (CCD) in four factors such as pH, adsorbent dosage, time contact and temperature was successfully employed for the investigation and optimization of dyes removal process. It was found that the removal of dyes increased significantly after the modification. This can be attributed to a large number of carboxyl groups were introduced to the backbone of chitosan. The results indicated that the experimental data fitted appropriately to pseudo- second order kinetic model (R 2 > 0.99). Also, the data for adsorption of two basic dyes onto Ch-g-Ea correlated reasonably well by Langmuir model (R 2 > 0.98). Based on the data of present study, Ch-g-Ea can be applied as an affective biopolymer adsorbent for removal of dyes from colored solutions. ß 2013 Elsevier Ltd. All rights reserved. * Corresponding author at: Dept. of Organic Colorants, Institute for Color Science and Technology, Hossein Abad Sq., 1668814811, Tehran, Iran. Tel.: +98 2122956126; fax: +98 2122947537. E-mail addresses: m.sadeghi@aut.ac.ir (M. Sadeghi-Kiakhani), gharanjig@icrc.ac.ir (K. Gharanjig). Contents lists available at SciVerse ScienceDirect Journal of Environmental Chemical Engineering jou r n al h o mep ag e: w ww .elsevier .co m /loc ate/jec e 2213-3437/$ – see front matter ß 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jece.2013.06.001