The Magnetic Properties and Dye Adsorption of Sericin-modified Magnetite Nanoparticles

The use of ferromagnetic nanoparticles as an adsorbent in water treatment has one distinct benefit: they can be removed simply by applying an external magnetic field. In this work, sericin-coated magnetite nanoparticles (SC-MNPs) were synthesized from ferric salts (Fe3+), ferrous salts (Fe2+), and sericin in alkaline solution at room temperature. The sericin, a waste protein produced during silk degumming, was demonstrated to control the size and morphology of the magnetite nanoparticles. Transmission electron microscopy clearly showed the presence of a sericin coating, and the particle size decreased from 16 +/- 5 nm for the untreated MNPs to 12 +/- 4 nm for the sericin-coated MNPs. FT-IR spectroscopy also confirmed the presence of sericin on the nanoparticles. The SC-MNPs were approximately 40% more effective than the unmodified MNPs in adsorption of methylene blue (a cationic dye) from water. Adsorption equilibrium was reached within 120 min. A good fit was found between the empirical adsorption data and the Freundlich isotherm, suggesting that adsorption was physical in nature, and that multiple layers were formed.

Automated summary

The use of sericin-coated magnetite nanoparticles as an adsorbent in water treatment proved to be effective in adsorbing cationic dyes from water, with a 40% higher efficiency compared to unmodified nanoparticles. The sericin coating was shown to control the size and morphology of the magnetite nanoparticles, resulting in improved adsorption performance. The adsorption process was physical in nature, forming multiple layers as confirmed by empirical data fitting well with the Freundlich isotherm.