Dye adsorption characteristics of magnetite nanoparticles coated with a biopolymer poly(gamma-glutamic acid)

作者：Inbaraj B Stephen; Chen B H^*

来源：Bioresource Technology, 2011, 102(19): 8868-8876.

DOI：10.1016/j.biortech.2011.06.079

• Magnetic nanoparticles
• Poly(gamma-glutamic acid)
• Biopolymer
• Methylene blue
• Adsorption

Magnetite nanoparticles coated with an anionic biopolymer poly(gamma-glutamic acid) (PGA-MNPs) were synthesized and characterized for their methylene blue dye adsorption capability. Both bare- and dye-loaded PGA-MNPs were characterized by FTIR, TEM and VSM measurements, revealing the PGA-MNPs to be superparamagnetic with average particle diameter being 12.4 nm and magnetization value 59.2 emu/g. The synthesized PGA-MNPs were stable in deionized, tap and river waters as well as in acidic and basic media. Redlich-Peterson and Langmuir models precisely described the isotherm and the maximum adsorption capacity was 78.67 mg/g. A pseudo-second-order equation best predicted the kinetics with a maximum adsorption attained within 5 min. Incorporation of sodium or calcium ions reduced the dye adsorption, while a raise in pH enhanced adsorption and a complete desorption occurred at pH 1.0. Dye removal mechanism by PGA-MNPs was probably due to electrostatic interaction through exchange of protons from side-chain cc-carboxyl groups on PGA-MNPs surface.

• 出版日期2011-10
• 单位河北医科大学