Evaluation of Efficiency of Persulfate Activated with Ultrasonic Waves in Phenanthrene Degradation from Soil Environments by Central Composite Design Method

Background and Purpose: PAHs and their derivatives have a complex and stable molecular structure with low biodegradability and have from the compounds in the crude oil. The object of this study was to evaluation of efficiency of persulfate activated with ultrasonic waves in Phenanthrene degradation from Soil environments by central composite design. The soil samples were homogenized and filtered using a 2.0 mm sieve. Then, Phenanthrene solution (PHE) was added into soil sample. In order to carry out the chemical oxidation process, Probe Ultrasonic Wave Generator place out inside the reaction chamber Contains Persulfate/soil slurry environment. A central composite design (CCD) was used for designing and optimizing the operation parameters such as sodium Persulfate concentration, Ultrasound intensity and contact time. The synergy of processes in the system was also studied in optimal conditions. ANOVA results indicated that the effect of persulfate concentration, ultrasound intensity and contact time and binary interactions were significant. The Persulfate concentration, has the most significant effect on the phenanthrene degradation. The highest efficacy of the phenanthrene degradation (%58.05) was obtained in the conditions: initial concentration of persulfate =0.2 mol, ultrasonic waves with power = %70, and contact time = 120 min. By applying S2O8-2 in a separate approach after 120 min the efficiency was 9.2% while at these conditions, the efficiency of the ultrasonic process was only 3.4%. By contrast, the combined PS/US process could remove %58.05 of phenanthrene. The results of this study indicated that, the application of the PS/US process is an effective method for purification of Phenanthrene contaminated soils.