RESUMO
The synergistic effect of CoFe2O4 on the capacity of bio-silica extracted from rice husk for the removal of methylene blue (MB) was investigated. The novel composite of cobalt ferrite/nano bio-silica was prepared by dispersing cobalt and iron salt in ratio 1:2 in a solution containing bio-silica, calcined at 700°C and characterized. The adsorption capacity of the composite (253.6â mg g-1) was higher than that of bio-silica (52.6â mg g-1), and the process was exothermic and spontaneous. Langmuir and Freundlich models were applicable to explain the adsorption isotherm, while pseudo-second-order and Elovich are best applicable for the kinetics mechanism. The amount of MB that was removed, increased with an increase in ionic strength due to dimerization of MB. Regeneration and reusability of the adsorbents showed that they are economically viable. Energy-filtered transmission electron microscopy (EFTEM) and Fourier transformed infrared (FTIR) analysis of MB-loaded adsorbent confirmed the adsorption of MB.
Assuntos
Poluentes Químicos da Água , Purificação da Água , Adsorção , Óxido de Alumínio , Compostos Férricos , Concentração de Íons de Hidrogênio , Cinética , Óxido de Magnésio , Azul de Metileno , Dióxido de Silício , Poluentes Químicos da Água/análiseRESUMO
We describe herein a novel type of monodisperse water-soluble magnetite nanoparticle coated with pheomelanin using an environmentally-friendly approach in aqueous medium. The results indicate superparamagnetic behaviour at room temperature and show improved negative contrast in T2-weighted MRI with a transverse relaxivity of 218 mM(-1) s(-1).