Abstract
This article reports effective removal of methylene blue (MB) dyes from aqueous solutions using a novel magnetic polymer nanocomposite. The core-shell structured nanosorbents was fabricated via coating Fe3O4 nanoparticles with a layer of hydrogel material, that synthesized by carboxymethyl cellulose cross-linked with poly(acrylic acid-co-acrylamide). Some physico-chemical properties of the nanosorbents were characterized by various testing methods. The nanosorbent could be easily separated from aqueous solutions by an external magnetic field and the mass fraction of outer hydrogel shell was 20.3 wt%. The adsorption performance was investigated as the effects of solution pH, adsorbent content, initial dye concentration, and contact time. The maximum adsorption capacity was obtained at neutral pH of 7 with a sorbent dose of 1.5 g L−1. The experimental data of MB adsorption were fit to Langmuir isotherm model and Pseudo-second-order kinetic model with maximum adsorption of 34.3 mg g−1. XPS technique was applied to study the mechanism of adsorption, electrostatic attraction and physically adsorption may control the adsorption behavior of the composite nanosorbents. In addition, a good reusability of 83.5% MB recovering with adsorption capacity decreasing by 16.5% over five cycles of sorption/desorption was observed.
Highlights
Synthetic organic dyes are one of the main factors that cause environmental contamination, and the problem has become more and more serious with the development of dyeing industries
For preparation of magnetic Carboxymethyl cellulose (CMC)-based hydrogel nanoparticles, CMC-g-p(AA-co-AM) hydrogel was synthesized outside the magnetic cores through free radical polymerization method by using MBA as a crosslinking agent and ammonium persulfate (APS) as an initiator
Thermogravimetric analysis (TGA) of magnetic nanocomposites were studied by using TGA analyzer (PYRIS 1, USA), 5.0–10.0 mg of the sample was heated from 30 ◦C to 700 ◦C with the heating rate of 10 ◦C min−1 under N2 flow of 10 cm3 min−1
Summary
Synthetic organic dyes are one of the main factors that cause environmental contamination, and the problem has become more and more serious with the development of dyeing industries. When the adsorbents have sizes in nanometer range, the magnetic interactions between particles can be reduced, bringing a superparamagnetic behavior that can diminish the particle aggregation while preserve the suspension stability [15,16] For this reason, magnetic nanosorbents have been designed and successfully applied for the removal of dye [17,18]. Carboxymethyl cellulose (CMC), a type of linear biopolymer, has been extensively utilized in pollution control owing to its outstanding characteristics of abundant, cheap, and biodegradable [19] It has good adsorption capacity and high affinity toward environmental pollutants because of the existence of functional groups (hydroxyl and carboxyl) to form complex by interaction with multivalent ions or cationic polymer [20,21].
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