Magnetic nanoparticle-mesoporous silica composites for lead(11) ion removal

Abstract

Mesoporous materials-magnetic nanoparticles (MNPs@MCM-48)-based adsorbents containing thiol and amino groups were prepared and studied for Pb(II) ion removal. The obtained products were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis and surface area analysis. SEM images and XRD patterns showed the particle sizes of around 180 nm and the cubic structure of MNPs@MCM-48, respectively. Surface areas of these adsorbents were determined to be ranging from 1,145 to 863 and 904 and m2/g for the unmodified to diethylenetriamine and 2-amiothiophenol functionalized MNPs@MCM-48 samples. For the optimized sorbent formulation, the maximum adsorption capacities of 202.13 and 125.00 mg/g were observed at pH 5 and 2 h contact time as determined by flame atomic absorption spectroscopy. The removal efficiency was as high as 100% for Pb(II) at 100 mg/L and below. These sorbents were separated from water-based samples by an external magnetic field and can be reused limitedly, as the sorbents could be used for the second cycle with slight changes in the removal efficiency and adsorption capacity.