Background: Dyes are resistant organic matter because they have an aromatic rings. Sulfate radical (SO₄^●-) is a powerful oxidative radical. The design via CCD, cause the process was done by high accurate and low-cost. The aim of this study was modeling of UV-EPS process to degradation of Acid Blue 25 dye via the CCD from aqueous.
Methods: In this experiment study, used to a photoelectrochemical reactor with two iron electrodes as an anode and two titanium electrodes as a cathode and Low-pressure mercury lamp (254 nm). The pH (2-4), Direct Current (0.75-1/5 A), S₂O₈^2- concentration (0/5-1/5 mg/l), reaction time (20-40 min) and initial concentration of AB25 (50 -100 mg/l) as a main independed variables were chosen. Also, COD, synergist effect, presence of radical scavenger and kinetic of reaction were studied in optimum conditions. Dye concentration and COD were measured by spectrophotometer (DR5000).
Results: The results illustrate that the efficiency of process is affected by the variables. Optimum condition obtained in pH=3/01, DC was 1/08 A, PS was 1/30 mg/l, reaction time was 34 minute and initial concentration equal to 50 mg/l. In this situation efficiency of process was 91 percent. The COD removal in these conditions was 69 percent. The correlation coefficient was 0.84 which indicates that the quadratic model is suitable for process design. The kinetics of reaction followed the first order kinetics. Reduce of efficiency of process in the presence of radical scavenger occur.
Conclusion: Optimizing via CCD reduces the number of runs and increases accuracy. This process has a high efficiency in dye and COD removal and this process can be used to reduce the pollutant loading form industrial wastewater, such as textile wastewater, before discharging into the environment.