Decolorization of Reactive Red 198 by ultrasonic process in aqueous solution

Background: Reactive dyes are extensively used in the textile industry due to their superior performance. However, the effluence of the waste containing such dyes into water resources can pose hazardous effects on the environment because of their carcinogenic, mutagenic, allergenic and toxic nature. This study explored the efficiency of the ultrasonic process in removing Reactive Red 198 dye from aqueous solutions. Methods: This research is a laboratory, experimental study carried out in the Environmental Health Engineering Research Center of Birjand University of Medical Sciences. Two ultrasonic devices with a constant frequency and adjustable temperature and time were applied. The effects of various operating parameters and optimal conditions for removal such as initial concentration of dye (20-200 mg/L), contact time (1-90 mines), temperature (20-50 oC), frequency (35,37 kHz) and pH (2-12) were investigated. Results: The mean efficiency rate of removing Reactive Red 198 dye in optimal conditions (with primary dye concentration of 20 mg/L, pH=3, retention time=50 min, temperature=50 oC) at a frequency of 37 kHz obtained 84.82%. This result at the frequency of 35 kHz was 82.6%. The minimum removal at a frequency of 35 kHz with a concentration of 200 mg per liter at a pH of 12 and a retention time of 1 minute was 29.35 and at the frequency of 37 kHz, it was 39.12. Conclusions: The results showed that the ultrasonic process has a high capacity to remove Reactive Red 198 dye from aqueous solutions. Besides, this procedure can prove more efficient in case the effective operational factors are optimized.