Elsevier

Applied Clay Science

Volumes 97–98, August 2014, Pages 1-7
Applied Clay Science

Research paper
Influence of magnetic field on the adsorption of organic compound by clays modified with iron

https://doi.org/10.1016/j.clay.2014.05.014Get rights and content

Highlights

  • Rapid synthesis of magnetic clay with maghemite iron phase

  • High removal of methylene blue by adsorption process

  • Organization of magnetic particles improvement in the adsorption with magnetic field

Abstract

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 organic 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 analysis 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 m2/g. FeMAG had part of this original structure broken, with an area of 177.1 m2/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.

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 technological applications. Clay has also become indispensable to modern life; it is the material of many kinds of applications and they are abundant 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 greater 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 materials 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 was focused on utilizing magnetic materials (such as magnetite and magnetite silica composites) for wastewater treatment (Ferroudj et al., 2013, Tuutijärvi et al., 2009, Wu et al., 2012, Yu and Yang, 2010) mainly because of simplicity and speed of separation when these materials are used with aqueous media.

In this work a simple and rapid synthesis was performed for obtaining modified clay with magnetic iron phases exposed. Furthermore, the modified materials were tested for their ability to remove the organic dye methylene blue (MB) from an aqueous medium. The possibility of improving the removal process by implementing a magnetic field was also evaluated.

Section snippets

Materials and methods

The cation exchange capacity (CEC) of montmorillonite, determined by the ammonium acetate method, is 1.75 mEq/g. Mineralogical composition showed the presence of 5 wt.% of quartz and 10 wt.% of feldspar. Through chemical analysis it was determined that the principal exchangeable cation is sodium and the following is the chemical composition:M1.41 (Al0.20 Si7.80)IV (Al2.69 Fe0.15 Mg1.11 Mn0.02)VI O20 (OH)4

Structural characterization

The FTIR spectra of the clays are presented in Fig. 2. A strong absorption in the region around 3600 cm 1 for the montmorillonite corresponds to the stretching of the hydroxyl groups and cations in the octahedral sheet. In these modified materials, this absorption appears overlapped with another in the region of 3400 cm 1 that is related to the presence of adsorbed water on the surface of the clays. Also in 1645 cm 1 the band can be ascribed to the vibration of water molecules (Zhao et al., 2012).

Conclusions

In this work, a montmorillonite was modified with iron; different heat treatments were responsible for the formation of materials with different characteristics and different iron phases. The magnetic clay was obtained by heat treatment in open furnace, and XRD indicated that the phase of iron present in this material is maghemite.

All clays showed high adsorption capacity of methylene blue, and the magnetic field positively influenced adsorption. For those which had no magnetism, the field

Acknowledgements

We greatly appreciate the Chemistry and Exact Science Departments of the Federal University of Lavras (UFLA), also the funding organizations for this project, National Counsel of Technological and Scientific Development (CNPQ) and Higher Education Co-ordination Agency (CAPES).

References (44)

  • F.I. Hai et al.

    Bioaugmented membrane bioreactor (MBR) with a GAC-packed zone for high rate textile wastewater treatment

    Water Res.

    (2011)
  • X. Hao et al.

    Magnetic field assisted adsorption of methyl blue onto organo-bentonite

    Appl. Clay Sci.

    (2012)
  • J. Hu et al.

    Removal and recovery of Cr(VI) from wastewater by maghemite nanoparticles

    Water Res.

    (2005)
  • J. Jung et al.

    Nitrate reduction by maghemite supported Cu–Pd bimetallic catalyst

    Appl. Catal. B Environ.

    (2012)
  • M. Kurian et al.

    Iron aluminium mixed pillared montmorillonite and the rare earth exchanged analogues as efficient catalysts for phenol oxidation

    J. Environ. Chem. Eng.

    (2013)
  • S. Letaief et al.

    Fe-containing pillared clays as catalysts for phenol hydroxylation

    Appl. Clay Sci.

    (2003)
  • N.M. Mubarak et al.

    Statistical optimization and kinetic studies on removal of Zn2 +using functionalized carbon nanotubes and magnetic biochar

    J. Environ. Chem. Eng.

    (2013)
  • F.G.E. Nogueira et al.

    Catalyst based on clay and iron oxide for oxidation of toluene

    Appl. Clay Sci.

    (2011)
  • E.F. Olasehinde et al.

    Application of Fenton reaction for nanomolar determination of hydrogen peroxide in seawater

    Anal. Chim. Acta.

    (2008)
  • L.C.A. Oliveira et al.

    Catalytic properties of goethite prepared in the presence of Nb on oxidation reactions in water: computational and experimental studies

    Appl. Catal. B Environ.

    (2008)
  • X.J. Peng et al.

    Montmorillonite-Cu(II)/Fe(III) oxides magnetic material as adsorbent for removal of humic acid and its thermal regeneration

    Chemosphere

    (2006)
  • E.G. Rightor et al.

    Iron oxide pillared clay with large gallery height: synthesis and properties as Fischer–Tropsch catalyst

    J. Catal.

    (1991)
  • Cited by (0)

    View full text