Research Paper Influence of magnetic field on the adsorption of organic compound by clays modified with iron Aline Auxiliadora Tireli a, ⁎, Francielle Candian Firmino Marcos b , Laís Ferreira Oliveira c , Iara do Rosário Guimarães a , Mário César Guerreiro a , Joaquim Paulo Silva c a Department of Chemistry, Federal University of Lavras, Lavras, 37200-000, Brazil b Department of Chemistry, University of São Paulo, São Carlos, 13566-581, Brazil c Department of Exact Science, Federal University of Lavras, Lavras, 37200-000, Brazil abstract article info Article history: Received 20 November 2013 Received in revised form 19 May 2014 Accepted 20 May 2014 Available online xxxx Keywords: Clay Adsorption Organic compound Magnetic field Insertion of iron into montmorillonite (Mt) resulted in two modified materials, when different treatments were used: i) pillared clay (FePILC) and ii) magnetic clay (FeMAG). The ability of the modified clays to remove the or- ganic dye methylene blue (MB) by adsorption was tested. Additionally, we evaluated the effects of adsorption after exposure to a pulsed magnetic field, the results were monitored by UV–vis spectroscopy and chemical anal- ysis of total organic carbon. All materials were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), temperature-programmed reduction (TPR), scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS) and specific surface area measurements. The catalytic activity of the clays modified with iron was evaluated in hydrogen peroxide decomposition reaction. The XRD patterns show the formation of crystalline iron phases on the surface of the clays, besides confirming the pillaring procedure for FePILC with a basal spacing of 1.79 nm, an increase of 0.53 nm over the montmorillonite. The specific surface area of FePILC was 210.9 m 2 /g. FeMAG had part of this original structure broken, with an area of 177.1 m 2 /g and magnetic properties demonstrated by the attraction to a permanent magnet. The TPR profiles and EDS indicated that the different heat treatments exerted great influence on the amount and phases of iron formed. The materials showed high capacity for removal of the MB dye, and the isotherms fit the Langmuir model. Adsorption of the dye significantly increased in the presence of a magnetic field, changing the Langmuir parameters and especially the maximum adsorption capacity for all materials. The best results were observed for FeMAG. © 2014 Elsevier B.V. All rights reserved. 1. Introduction Pigments and dyes are disposed into wastewaters from various industries, mainly by the textile production (Fatimah et al., 2010; Hai et al., 2011). They are a serious problem when dealing with textile waste because they are water soluble, chemically and photolytically stable (Guimarães et al., 2012). Effluents containing dyes must not be disposed in natural bodies, because they do not allow solar light penetration and decrease the dissolved oxygen amount, damaging aerobic processes (Banković et al., 2012). Clays have been used by humanity since ancient times for manufacturing, ceramic objects, and more recently in several techno- logical applications. Clay has also become indispensable to modern life; it is the material of many kinds of applications and they are abun- dant in nature, inexpensive and environmentally friendly (Bergaya et al., 2006; Carretero and Lagaly, 2007). Their structural properties can be modified by simple methods such as pillaring, to produce materials with higher surface area, porosity, thermal stability and great- er capacity for adsorption and/or degradation of contaminants (Bergaya et al., 2006; Kurian et al., 2012; Tong et al., 2009). The pillared clays, also cited by the abbreviation PILC (Pillared InterLayered Clays), have achieved considerable interest in their use as catalysts and adsorbents in recent years (Gil et al., 2011). The pillarization promotes an increase in basal spacing and surface area, which provides better accessibility of the molecules to the active sites present inside of the clay structure (Gil et al., 2011; Yang et al., 2013). The list pertaining to the engineering and application of these materials is extensive; there are several publications with different aspects of the theme in the recent literature. Materials containing iron, like iron oxide pillared clay, become very interesting when they display magnetic attraction in combination with high specific surface area. Furthermore, iron is usually employed for adsorbents fabrication, because of the low cost (Mubarak et al., 2013). These represent an innovative and promising class of new mate- rials for removal of contaminants such as organic dyes (Banković et al., 2012; Hou et al., 2010) and contaminants in aqueous media (Mubarak et al., 2013; Rivagli et al., 2014; Zhang et al., 2010). In addition, attention Applied Clay Science 97–98 (2014) 1–7 ⁎ Corresponding author. Tel./fax: +55 35 38291271. E-mail address: aatireli@gmail.com (A.A. Tireli). http://dx.doi.org/10.1016/j.clay.2014.05.014 0169-1317/© 2014 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Applied Clay Science journal homepage: www.elsevier.com/locate/clay