Ozonation of naphthalene sulfonic acids in aqueous solutions: Part Ⅱ―Relationships of their COD, TOC removal and the frontier orbital energies

摘要

This paper evaluated the COD, TOC removal and molecular frontier energies in the ozonation of naphthalene sulfonic acids (NSAs). It was found that both COD and TOC degradation of the 11 compounds followed the pseudo-first-order kinetic and the reaction rate constants with ozone varied widely. A linear relationship between logarithm of global COD degradation rate constant and the energy of the highest occupied molecular orbit, E_(homo) was obtained for these NSAs with a regression coefficient of 0.88 and a slope of 0.4672eV~(-1). TOC degradation kinetics also reached similar results with a regression coefficient of 0.90 and a slope of 0.9336eV~(-1). The results of correlation analysis suggested that TOC and COD removal in ozonation of NSAs follow the frontier orbital theory and can be predicted by E_(homo), which indicated that electrophilic effect was the main factor in the ozonation of NSAs. Therefore, it is possible to improve the biodegradability of dyestuff wastewater bearing mainly NSAs by ozonation at an accepted cost and evaluate the economy of ozonation process.