Modified chitosan as an economical support for hematin: application in the decolorization of anthraquinone and azo dyes

AGOSTINA CÓRDOBA; IVANA MAGARIO; MARÍA LUJÁN FERREIRA

JOURNAL OF CHEMICAL TECHNOLOGY AND BIOTECHNOLOGY

JOHN WILEY & SONS LTD

Lugar: Londres; Año: 2014

0268-2575

BACKGROUND:Azo and anthraquinone dyes have been successfully decolorized using enzymatic and biomimetic homogeneous systems.1,2 Hematin, a horseradish peroxidase (HRP) biomimetic, immobilized on chitosan via glutaraldehyde couplingwas able to decolorize Alizarin Red S and Orange II solutions. A Doehlert experimental design and response surface analysis was applied to determine conditions for optimalmass of catalyst and catalytic efficiency of the immobilization procedure.RESULTS: The catalysts with supported hematin showed 33% activity (relative to homogeneous hematin as 100%) in decolorization reactions. After six reuses the catalytic activity was maintained at 60% of the initial one. Hematin anchoring to chitosan without alteration of the iron-porphyrin ring was confirmed by ICP, FTIR and UV/visible spectrophotometric methods. In addition, the effect on hematin activity in the decolorization of aminopropyltriethoxysilane (APTS) as a spacer arm between hematin-glutaraldehyde and chitosan was studied.CONCLUSIONS: An economical heterogeneous catalyst alternative to HRP has been obtained. The spacer arm improves the catalyst ́s performance with activities as high as 57% relative to homogeneous hematin. These results support the notion that the activity loss of supported hematin is caused by the restricted access to Fe of the bulky phenolic dyes.