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EFFECT OF THE SURFACE CHARGE ON THE ADSORPTION CAPACITY OF CHROMIUM(VI) OF IRON OXIDE MAGNETIC NANOPARTICLES PREPARED BY MICROWAVE-ASSISTED SYNTHESIS
Gallo-Cordova, A., M. del Puerto Morales, and E. Mazario | Water 11(11):2372
Superparamagnetic iron oxide nanoparticles (MNP) with different surface charges were tested as nanosorbents to remove Cr(VI) from aqueous solution. A microwave polyol-mediated method was used to synthesize uniform magnetic nanoparticles (~12 nm). Tetraethyl orthosilicate (TEOS) and (3-aminopropyl) triethoxysilane (APTES) were grafted onto the nanoparticle's surface to provide a variation in the surface charge. The adsorptive process of Cr(VI) was evaluated as a function of the pH, the initial concentration of Cr(VI), and contact time. Kinetic studies were best described by a pseudo-second-order model in all cases. TEOS+MNPs barely removed Cr(VI) from the media. Non-grafted particles and APTES+TEOS+MNP followed the Langmuir model with maximum adsorption capacities of 15 and 35 mgCr/g, respectively. Cr(VI) adsorption capacities abruptly increased when the surface became positively charged as the species coexisting at the experimental pH were negatively charged. These particles were found to be highly efficient in water remediation due to their 100% reusability after more than six consecutive adsorption/desorption cycles. This article is Open Access at https://www.mdpi.com/2073-4441/11/11/2372
Superparamagnetic iron oxide nanoparticles (MNP) with different surface charges were tested as nanosorbents to remove Cr(VI) from aqueous solution. A microwave polyol-mediated method was used to synthesize uniform magnetic nanoparticles (~12 nm). Tetraethyl orthosilicate (TEOS) and (3-aminopropyl) triethoxysilane (APTES) were grafted onto the nanoparticle's surface to provide a variation in the surface charge. The adsorptive process of Cr(VI) was evaluated as a function of the pH, the initial concentration of Cr(VI), and contact time. Kinetic studies were best described by a pseudo-second-order model in all cases. TEOS+MNPs barely removed Cr(VI) from the media. Non-grafted particles and APTES+TEOS+MNP followed the Langmuir model with maximum adsorption capacities of 15 and 35 mgCr/g, respectively. Cr(VI) adsorption capacities abruptly increased when the surface became positively charged as the species coexisting at the experimental pH were negatively charged. These particles were found to be highly efficient in water remediation due to their 100% reusability after more than six consecutive adsorption/desorption cycles. This article is Open Access at https://www.mdpi.com/2073-4441/11/11/2372
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