Use of an lmproved Chemiluminescence Assay for Non-Intrusive Measurement of Hydroxyl Radicals in a Biomimetic Pulp Bleaching Model System

摘要

A chemiluminescence assay was used to measure the production of hydroxyl radicals (.OH) in aqueous solutions of hydrogen peroxide and iron-containing catalysts. Preliminary experiments evaluating assay sensitivity revealed that one of the required reagents, phthalhydrazide (PtH), interfered with the studied reactions. In addition, undesirable degradation of the chemiluminescent form of PtH was observed. By removing PtH from reaction solutions and modifying the published procedures, a successful non-intrusive method for measurement of .OH was obtained. The modified assay was used to compare the rate of .OH generation in solutions of H_2O_2, either FeSO_4 or Fe-EDTA and a substrate, lignosulfonate. This "bio- mimetic" pulp bleaching system is meant to simulate naturally occurring biological reactions utilized for degradation of lignins by wood-degrading fungi. Results from these experiments show that FeSO_4 produced more .OH than Fe-EDTA. The improved non-intrusive chemiluminescence assay has proven to be an excellent tool for investigating the role of the .OH in biomimetic pulp bleaching and potentially other systems.