Enhancement in mineralization of a number of natural refractory organic compounds by the combined process of sonolysis and ozonolysis (US/O3)

Abstract

As an advanced oxidation process, the combination of sonolysis (US)/ozonolysis (O(3)) was investigated on the treatment of tannic acid (TA) and humic acid (HA). In this study, biodegradable chemicals were found by the molecular weight and GC-MS analysis method, and mineralization rate and synergetic effects were also studied. For the water samples prior to the treatment of US/O(3), ratios of molecular size higher than 5000 and 2000 Da for HA and TA, detected by the ultra filtration method, were 90.25% and 89.53%, respectively. However, after 0.5h of reacting, this ratio rapidly reduced to 3% and 4%, and the ratios of molecules for HA and TA less than 500 Da rapidly increased from 0.8% to 41% and from 0.65% to 39%, respectively. In the results of chemical oxygen demand (COD(Cr)) and total organic carbon (TOC) reductions, the US/O(3) process also showed synergetic effect by US/O(3) for COD(Cr) of HA and TA were 19% and 11%, and those for TOC of HA and TA were 0% and 1%, respectively. The major by-products of the oxidation process included formaldehyde, acetone, hydroxylamine, etc. Biological decomposable materials could be indirectly inferred by measuring the molecular weights and intermediates.