Synergistic effect of a spinel ferrite on the adsorption capacity of nano bio-silica for the removal of methylene blue

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 degrees C and characterized. The adsorption capacity of the composite (253.6 mg g(-1)) was higher than that of bio-silica (52.6 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.

Automated summary

The study investigated the synergistic effect of CoFe2O4 on bio-silica extracted from rice husk for methylene blue removal. A novel composite of cobalt ferrite/nano bio-silica with high adsorption capacity was prepared. The increase in ionic strength led to dimerization of MB and higher removal efficiency. Regeneration and reusability of the adsorbents proved to be economically viable.