Simultaneous adsorption–degradation of organic dyes using MnFe2O4/calcium alginate nano-composites coupled with GOx and laccase

• MnFe2O4 nanoparticles were synthesized by co-precipitation method.
• Glucose oxidase and laccase were immobilized on MnFe2O4 nanoparticles.
• GOx/MnFe2O4/calcium alginate and laccase/MnFe2O4/calcium alginate nanocomposites were prepared.
• The effect of various parameters on the removal of dyes was studied.

In this study, glucose oxidase and laccase enzymes were immobilized on MnFe2O4 nanoparticles, which were synthesized by co-precipitation method. The nanocomposites of glucose oxidase/MnFe2O4/calcium alginate, laccase/MnFe2O4/calcium alginate, and MnFe2O4/calcium alginate were prepared by trapping enzyme/nanoparticles in calcium alginate. The size, morphology and crystallite phase of MnFe2O4 nanoparticles were investigated by SEM and XRD techniques, respectively. FT-IR spectroscopy was used to examine the functional groups of the nanoparticles before and after the immobilization of each enzyme. Also, prepared absorbents were applied for the decolorization of three model dye wastewaters of methylene blue, indigo and acid red 14. Decolorization of these dyes at pH 7 by laccase/MnFe2O4/calcium alginate during 1 h was observed 82.13, 25.09, and 20.42%, respectively. The maximum amount of decolorization of indigo and acid red 14 dyes at pH 5 and 3 by glucose oxidase/MnFe2O4/calcium alginate for 1 h were 44.03 and 46.5%, respectively; and decolorization of methylene blue at pH 9 after 3 h reached 93.46%.