Investigation of the photocatalytic degradation of brown water natural organic matter by size exclusion chromatography

摘要

Herein we report on the photocatalytic degradation of natural organic matter from a bog lake(Lake Hohloh,Black Forest,Germany)as followed by size exclusion chromatography with dissolved organic carbon(DOC)and ultraviolet(lambda = 254 am)detection(SEC-DOC and SEC-UV).When irradiating this humic-rich water in the presence of 0.5 g L~(-1)titanium dioxide(P25),we found a preferential degradation of the higher molecular weight DOC fraction.This was coupled to growth of the middle and small DOC fractions.Mineralization proceeded in two distinct steps:a first stage without noticeable mineralization,followed by a phase of steady decrease in dissolved organic carbon.Formic,oxalic,succinic and glutaric acids were found in the irradiated samples and contribute significantly to the bioavailable DOC after irradiation,which favors bacterial regrowth.