MINERALIZATION OF BISPHENOL A BY HETEROGENEOUS CATALYTIC OZONATION
Keykavoos Amand, Rozita
Emerging pollutants especially the ones well known as endocrine disrupting compounds (EDCs) have attracted much attention recently due to the toxic effects of these materials even at very low concentration on both animals and humans. Bispenol A (BPA) is an important EDC with very high consumption in industry and also high release to the environment. Among different techniques to remove organic compounds including BPA from water, ozonation is an established method but it is not sufficient to completely mineralize pollutants. As a result, heterogeneous catalytic ozonation offers a promising potential in removal techniques by not only increasing the mineralization of organic compounds, but also decreasing the consumption of ozone and consequently improving the feasibility of process. The main aim of this study is evaluating mineralization of BPA in non-catalytic ozonation systems and heterogeneous catalytic ozonation processes in the presence of suitable catalysts. More specifically, effect of different parameters in non catalytic ozonation of BPA such as BPA and ozone initial concentration, pH and temperature were investigated. Non-catalytic ozonation was found to be able to accomplish complete degradation of the initial BPA in less than 4 minutes, but unable to convert the by-products of BPA ozonation so that, only 35% conversion of the total organic carbon (TOC) was achieved in 60 minutes. Adding proper catalysts to system can significantly enhance the efficiency of mineralization. Activated carbon, alumina and Mn- alumina are three catalysts investigated in this project and each of them showed reasonable improvement in term of TOC conversion. Activated carbon mostly suitable good adsorbent and it removed 90 % of BPA in the absence of ozone. On the other hand, alumina and Mn- alumina were successful in combination with ozone. Catalytic ozonation in the presence of alumina and Mn- alumina attained TOC conversions of about 90 % for both of the cases. Furthermore it was shown that by changing the catalyst particle size from pellets to powders, TOC conversion increases from 44% to 90% which showed the significant effect of mass transfer limitation due to intra-particle diffusions. Dosage of alumina (0.5 to 4 g/L) did not show a strong effect on the TOC removal. Alumina and Mn- alumina proved to be strong adsorbent for acidic by-products of BPA reaction. Catalyst reusability and deactivation studies indicated that catalysts became deactivated by the adsorption of carbonaceous by-products after few cycles of the reaction in the absence of ozone. Whereas, in the presence of ozone these adsorbed carbons are consistently oxidized by ozone and the catalyst surface remains fresh. A kinetics study was completed for TOC removal of BPA mineralization systems and estrogenicity test indicating that ozonation improves reduction of estrogenicity of BPA, but further decrease can be attained by using alumina as an effective catalyst in ozonation system.
DegreeMaster of Science (M.Sc.)
CommitteeNemati, Mehdi; Rodriguez-Prado, Arcadio
Copyright DateAugust 2012
ozonation, catalytic ozonation, bisphenol A