Unusual dye adsorption behavior of κ-carrageenan coated superparamagnetic nanoparticles
Introduction
Dyes are present in the effluents of a number of industries, including textile, paper, plastic, cosmetic, leather and rubber. The discharge of dyes in water supplies is a matter of concern due their harmful impact on the environment. Most of these compounds cause depletion of water’s oxygen that may result in death of the aquatic life. In addition several dyes and their degradation products exhibit toxicity and potential mutagenic and carcinogenic effects [1]. Methylene blue (Fig. 1a) is commonly used for dying textiles and wood [2] and although MB is less hazardous as compared to other dyes, it has also various harmful effects namely because acute exposure causes nausea and chest pain [3].
The methods used for the removal of methylene blue and other cationic dyes from industrial effluents include chemical precipitation [4], photochemical degradation [5] and adsorption [2], [6]. Among these purification techniques, adsorption is by far the most commonly used due to its simplicity, low cost and effectiveness. A number of materials have been explored as dye adsorbents, such as inorganic materials, activated carbon and inexpensive waste materials [2], [7]. The research for environmentally friendly and low-cost dye adsorbents has raised the attention to biopolymers obtained from renewable resources, such as polysaccharides. Polysaccharides have specific functional groups in their structure which explains their affinity towards a wide diversity of molecules and ions. The list of low cost polysaccharides tested as dye adsorbents is extensive [8] and include alginate [9], chitosan [10], [11], [12], cyclodextrins [13] and starch [14].
Carrageenan comprises a family of linear water-soluble sulfated polysaccharides extracted from red seaweeds. Due to their biocompatibility and ability to form hydrogels, carrageenan has been extensively used as gelling agent in food and pharmaceutical industries [15]. κ-Carrageenan (Fig. 1b) bears one sulfonate group per disaccharide unit, that corresponds to ca. 20 wt% sulfate content. It forms hydrogels stabilized by alkali-metal cations, such as potassium ions and presents the best gelation properties within the carrageenan family, thus being selected as adsorbent for this study. The sulfonate anions of carrageenan are the groups primarily responsible for the interaction with cationic dyes [16]. Taken together, the ability of carrageenan to form complexes with cationic dyes [16] and their gelling properties, make these biopolymers interesting candidates for dye adsorbents in wastewater treatment.
Limitations associated to the separation of dispersed polymer based adsorbents from the treated effluents have restrained their use mostly in fixed-bed systems or packed in sorption columns [8]. Hence, magnetic adsorbents appear as advantageous alternatives that allows the easy magnetically assisted separation of the adsorbents from the treated effluents [17], [18]. Magnetic nanoparticles (MNPs) such as iron oxide nanoparticles, besides bearing a large surface area favorable for adsorption processes, possess magnetic features which enables them to be separated within a short time by employing an external magnetic field [18], [19], [20]. Moreover iron oxide nanoparticles (e.g. magnetite – Fe3O4 and maghemite-γ-Fe2O3) show no severe toxicity hence these materials are attractive for the development of water purification systems. Polymer coated MNPs have received much attention since the polymer shell may prevent the aggregation of the magnetic cores and improve the dispersion stability of the nanoparticles in aqueous medium. The combination of MNPs with polysaccharides for dye adsorption from wastewater was investigated in the past for cyclodextrins [13], alginate [9] and chitosan [12], [21], [22]. Magnetic κ-carrageenan hydrogels have been explored for biomedical purposes [23], [24], [25] but to the best of our knowledge, the use of this polysaccharide for coating magnetic nanoparticles for the removal of cationic dyes from aqueous solutions is an unexplored strategy, despite its affinity to cationic dyes being known for several years [16].
In this work we report the preparation of κ-carrageenan coated magnetite (Fe3O4) nanoparticles and their applications for the removal of methylene blue from aqueous solutions. The removal capability was evaluated in a batch mode process and the kinetics and equilibrium of the adsorption were investigated, as well as the reusability of the sorbents. The system reported here combines the possibility of easy and fast magnetic separation with the advantages of low cost biodegradable materials, resulting in efficient eco-friendly materials for wastewater treatment.
Section snippets
Materials
κ-Carrageenan (300.000 g/mol, Fluka Chemie), potassium chloride (KCl) (>99%, Sigma–aldrich), ammonia (NH4OH) (25% NH3, Riedel-de-Häen), iron (III) chloride hexahydrated (FeCl3⋅6H2O, >99%, Sigma–aldrich), iron (II) chloride tetrahydrated (FeCl2⋅4H2O, >99%, Sigma–aldrich), methylene blue (C16H18ClN3S, Riedel-de Häen), nitric acid (HNO3 25%, Panreac) and hydrochloric acid (HCl 37%, Fluka) were used as received.
Preparation of κ-carrageenan coated magnetic nanoparticles
Magnetic iron oxide nanoparticles (NPs) were first synthesized using the co-precipitation
Chemical and structural properties
Magnetic iron oxide nanoparticles (MNPs) were prepared in aqueous medium using the co-precipitation method [29]. The powder XRD patterns of the as prepared NPs (bare MNPs) matches the typical diffraction pattern of magnetite (Fe3O4) thus confirming the presence of this crystalline phase in the powdered sample (Fig. 2a).
Zeta potential measurements (Table 1) revealed a negative surface charge (−37.7 ± 7.2 mV) for the colloids composed of bare MNPs. As expected, the treatment of bare MNPs with nitric
Conclusions
Magnetite nanoparticles coated with κ-carrageenan were prepared and evaluated as magnetic sorbents for the removal of methylene blue (MB) from aqueous solutions, using a simple NdFeB magnet. Under the experimental conditions used (23 °C, pH 9), MB could be recovered fast (5 min) and efficiently, due to electrostatic interaction with the sulfonate moieties of carrageenan. The MB adsorption capacity displayed by these materials was higher than other magnetic sorbents previously reported. The
Acknowledgements
The authors acknowledge FCT – Fundação para a Ciência e Tecnologia (ERA-Eula/0003/2009, PTDC/CTM-NAN/120668/2010, Pest-C/CTM/LA0011/2011, post-doctoral grant SFRH/BPD/66407/2009 (A.V. Girão)), FSE and POPH for funding. We thank the RNME (National Electronic Microscopy Network) for TEM facility and to Dr. G. Goya (INA, Zaragoza, Spain) for magnetic measurements. The authors are very grateful to MSc. M.C. Azevedo for technical support.
References (39)
- et al.
Adsorption of methylene blue on low-cost adsorbents: a review
J. Hazard. Mater.
(2010) - et al.
Pilot plant scale reactive dyes degradation by solar photo-Fenton and biological processes
J. Photochem. Photobiol. A – Chem.
(2008) - et al.
Methylene blue adsorption by algal biomass based materials: biosorbents characterization and process behaviour
J. Hazard. Mater.
(2007) - et al.
Adsorption of anionic dyes from aqueous solutions using chemically modified straw
Bioresour. Technol.
(2012) Recent developments in polysaccharide-based materials used as adsorbents in wastewater treatment
Prog. Polym. Sci.
(2005)- et al.
Dye removal from aqueous solution by magnetic alginate beads crosslinked with epichlorohydrin
J. Hazard. Mater.
(2010) - et al.
Application of chitosan, a natural aminopolysaccharide, for dye removal from aqueous solutions by adsorption processes using batch studies: a review of recent literature
Prog. Polym. Sci.
(2008) - et al.
Removal of various cationic dyes from aqueous solutions using a kind of fully biodegradable magnetic composite microsphere
Chem. Eng. J.
(2013) - et al.
Synthesis of carboxymethyl-beta-cyclodextrin conjugated magnetic nano-adsorbent for removal of methylene blue
Colloid Surf. A – Physicochem. Eng. Asp.
(2010) - et al.
Adsorption behaviors of acid and basic dyes on crosslinked amphoteric starch
Chem. Eng. J.
(2006)
Carrageenans: biological properties, chemical modifications and structural analysis – a review
Carbohydr. Polym.
Water purification using magnetic assistance: a review
J. Hazard. Mater.
Use of iron oxide nanomaterials in wastewater treatment: a review
Sci. Total. Environ.
Efficient removal of cationic dyes from aqueous solution by polymer-modified magnetic nanoparticles
Chem. Eng. J.
Synthesis and characterization of magnetic β-cyclodextrin-chitosan nanoparticles as nano-adsorbents for removal of methyl blue
Int. J. Biol. Macromol.
Adsorption of acid dyes from aqueous solutions by the ethylenediamine-modified magnetic chitosan nanoparticles
J. Hazard. Mater.
Impact of magnetic nanofillers in the swelling and release properties of kappa-carrageenan hydrogel nanocomposites
Carbohydr. Polym.
Pseudo-second order model for sorption processes
Process. Biochem.
Recovery, concentration and purification of phenolic compounds by adsorption: a review
J. Food Eng.
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