A B S T R A C TIn this study, glutaraldehyde cross-linked magnetic chitosan nanoparticles (GMCNs) were prepared through cross-linking modification of magnetic chitosan nanoparticles using glutaraldehyde as a cross-linker that exhibited excellent Metanil Yellow (MY) adsorption performance. The characterization of the GMCNs was performed by Fourier transform infrared spectroscopy, transmission electronmicroscopy, scanning electron microscopy, dynamic light scattering, and vibrating sample magnetometry analyses. Adsorption characteristics of MY from aqueous solution onto GMCNs have been studied. During the studies, various essential factors influencing the adsorption, like adsorbate concentration, amount of adsorbent, pH of the solution, and contact time have been monitored. The equilibrium was achieved within 17 h at pH 4, and the adsorption data obeyed the Langmuir equation with a maximum adsorption capacity of 625 mg/g and a Langmuir adsorption equilibrium constant of 5.2 × 10 −4 dm 3 /mg at 25˚C. The adsorption kinetics of MY at different initial dye concentrations was evaluated by the first-order and second-order models. The kinetic studies of MY adsorption showed that the adsorption process followed a second-order kinetic model. Furthermore, the GMCNs can be regenerated and reused through dye desorption in alkaline solution at pH 10. Adsorption results for reusability were 100, 93, and 65%, respectively, for three repeats.
In this study, R(+)-α-methylbenzylamine-modified magnetic chiral sorbent was synthesized and assessed as a new enantioselective solid phase sorbent for separation of mandelic acid enantiomers from aqueous solutions. The chemical structures and magnetic properties of the new sorbent were characterized by vibrating sample magnetometry, transmission electron microscopy, Fourier transform infrared spectroscopy, and dynamic light scattering. The effects of different variables such as the initial concentration of racemic mandelic acid, dosage of sorbent, and contact time upon sorption characteristics of mandelic acid enantiomers on magnetic chiral sorbent were investigated. The sorption of mandelic acid enantiomers followed a pseudo-second-order reaction and equilibrium experiments were well fitted to a Langmuir isotherm model. The maximum adsorption capacity of racemic mandelic acid on to the magnetic chiral sorbent was found to be 405 mg g(-1). The magnetic chiral sorbent has a greater affinity for (S)-(+)-mandelic acid compared to (R)-(-)-mandelic acid. The optimum resolution was achieved with 10 mL 30 mM of racemic mandelic acid and 110 mg of magnetic chiral sorbent. The best percent enantiomeric excess values (up to 64%) were obtained by use of a chiralpak AD-H column.
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