Chemical studies on the ozonation of synthetic glucose-glycine melanoidin as model color pollutant

Issue Date

6-2006

Abstract

Synthetic melanoidin (a model color pollutant) was prepared by heating an aqueous solution of 1.0 M glucose, 1.0 M glycine and 0.5 M sodium carbonate at 121˚C for 3 hours. It was dialyzed against distilled water, eluted through a Sephadex G-75 column and then freeze-dried. The kinetics of ozonation of the prepared melanoidin was studied in unbuffered and buffered solutions (pH 3.5, 5.0, 6.5, 7.0, 8.5 and 10. The reaction was found to obey first-order and half-order kinetics based on absorbance data at 475 nm and 280 nm, respectively. After two hours of ozonation, melanoidin decolorization was in the range 64-94% , decolorization was greater at lower pH values. Decolorization of the unbuffered melanoidin solution was 97.2%. Reduction in absorbance at 280 nm generally increased from 31% to 51% as the pH was changed from 10 to 3.5; the value for unbuffered solution was 74.9% Reduction of MW was 78% and indicated melanoidin depolymerization. The UV-visible spectra of synthetic melanoidin after ozonization showed a decrease in absorbance at 230-280 nm. a shift towards shorter wavelengths of the absorption peak at 300-400 nm and a decrease in absorbance in the visible region. The IR spectra showed the presence of-OH, C=C and C-O groups in both unozonated and ozonated melanoidins. An increase in peak intensity corresponding to the C-O stretch was observed for the ozonated sample. The results showed that ozonation is effective in decolorizing melanoidin.

Source or Periodical Title

Journal of Environmental Science and Management

ISSN

0119-1144

Volume

9

Issue

1

Page

44-59

Document Type

Article

College

School of Environmental Science and Management (SESAM)

Frequency

semi-annually

Physical Description

diagram, tables, graphs

Language

English

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