This graph shows the effect of inlet ozone concentration on the removal rates of COD and TOC for water samples.
This graph shows the effect of inlet ozone concentration on the removal rates of COD and TOC for water samples. The reaction conditions were as follows: COD was 500 mg·L-1, pH of the feed was 6.63, catalyst dosage was 2 g·L-1, reaction time was 90 min, reaction temperature was 20°C, ozone concentration was 60 mg·L-1, and different inlet ozone concentrations were used to react and measure their COD and TOC.
From the figure, it can be seen that when other conditions remain unchanged, the removal rate of COD is significantly higher than that of TOC when the inlet ozone concentration is between 0.1 and 0.9 L·min-1. As the inlet ozone concentration increases, the gap between the two decreases gradually, reaching a high value of 88.71% and 85.39% at an inlet ozone concentration of 1.0 L·min-1, respectively.
It can be concluded that under low inlet ozone concentrations, the process of ozone oxidation of phenol has selectivity, primarily converting it into non-completely oxidized products such as ortho-dihydroxybenzene and maleic acid. Before and after the reaction, there are significant changes in COD but relatively small changes in TOC. Based on this, an inlet ozone concentration of 1 L·min-1 is considered optimal.
