Ozone and organics

[simonh]

Hi Randy,

I've been reading the "Marine Dissolved Organic Matter" book over the Christmas holidays.

One question I had relating to reef tanks, and putting aside all the other concerns about ozone byproducts. When people use ozone in a reef tank does it oxidise all organics the same rate or are some suchas humic substances more easily oxidised than other LMW refractory organics?

[Randy Holmes-Farley]

I think it oxidizes some organic functional groups on organic molecules much faster than others. Things like carbon carbon doube bonds, for example, would oxidize rapidly. Some funtional groups would react more slowly. A methyl group, for example, would be slower. So some organic molecules will have a very reactive part or parts, and others will have less reactive parts.

Once some new functional groups are added to these refractory molecules, then bacteria might really like them better, and they may take the whole molecule apart even if ozone only nicked it.

Next week when back at work, I can give a list of organic functional groups that are readily reacted with ozone, and those not readily reacted with ozone (or perhaps others with appropriate books hand can post comments before then). :)

[simonh]

Thanks Randy.

[Randy Holmes-Farley]

:thumbsup:

Happy New Year. :)

[Randy Holmes-Farley]

Here's an interesting recent reference. I'll get more later. :)

Application of fluorescence spectroscopy in the studies of natural organic matter fractions reactivity with chlorine dioxide and ozone. Swietlik, Joanna; Sikorska, Ewa. Department of Water Treatment Technology, Faculty of Chemistry, Adam Mickiewicz University, Poznan, Pol. Water Research (2004), 38(17), 3791-3799.

Abstract

The compn. of natural org. matter (NOM) fractions before and after the reaction with ClO2 as well as ozone was studied by total luminescence spectroscopy (TLS) and synchronous scanning fluorescence measurements. The excitation-emission matrixes spectra (EEMs) of natural as well as oxidized NOM fractions revealed 2 well-resolved bands with maxima at Ex/Em of 250-265/422-452 nm and at Ex/Em 300-336/414-446 nm ascribed to humic and fulvic material. The study of emission and synchronous spectra also confirmed the presence of protein-like constituents in all examd. NOM fractions. The study of EEMs proved, that oxidn. of all NOM fractions with ClO2 caused mainly the break-up of mols. into smaller fragments and a decrease of the aromaticity. Changes in EEMs after the oxidn. of individual NOM fractions with O3 confirmed the formation of a significant amt. of ozonization byproducts, i.e. carboxylic acids, aldehydes and ketones during the oxidn. process. The fluorescence studies confirmed relatively high reactivity of all NOM fractions with ClO2 as well as with ozone.