Transformation of dissolved organic matter by oxidative polymerization with horseradish peroxidase

摘要

Dissolved organic matter (DOM) has significant influence on the transport and fatenof contaminants in multiple phases and it has potential hazard by acting as a precursornof disinfection by-products in water supply. The changes in DOM characteristics, especiallynby oxidative polymerization might result in different behaviour in the interaction with manyncontaminants. The aim of this work was to verify the catalytic effects of peroxidase on oxidativenpolymerization of humic and fulvic substances by examination of the structural characteristics.nTransformation of humic acid (HA) and fulvic acid (FA) by oxidative polymerization catalyzed bynhorseradish peroxidase and hydrogen peroxide were investigated. Size exclusionnchromatography, excitation–emission matrices spectra (EEMs), synchronous fluorescencenspectra, and infrared spectroscopy was used to evaluate the structural transformation of HAnand FA. Molecular weight of HA and FA was continuously changed and their weight-averagenmolecular weight (MWw) reached maximum after 8 h. The MWw of HA and FA were proportionallynincreased with a dosage of horseradish peroxidase and hydrogen peroxide, indicating that HAnand FA was transformed into larger and complex molecules. Spectroscopic results indicated thatnHA and FA structure contains strong polycyclic aromatic structures with more aromatic rings andna higher degree of conjugation.