Diethyl Phthalate Removal by Continuous-Flow Ozonation: Response Surface Modeling and Optimization

An experimental design methodology was applied for response surface modeling and optimization of diethyl phthalate (DEP) removal from synthetic wastewater by continuous-flow ozonation. The five independent variables considered were the initial concentration of DEP, initial solution pH, liquid flow rate, gas flow rate, and ozone concentration in the inlet gas. Using the Box–Behnken design, two quadratic models were developed as a functional relationship between respectively DEP removal efficiency and ozone mass transfer and the independent variables considered. It was found that all the factors considered have a significant effect on the removal efficiency response, except for the gas flow rate which did not influence DEP removal in the ranges considered. The results show that the ozonation efficiency can be predicted and are in very good agreement with the experimental data. Optimal conditions for two different sets of constraints were determined.