Development of an Empirical Kinetics Model for Sono-Degradation of Malachite Green: Evaluation of Electrical Energy Per Order

Abstract

Background: Sonolysis a method that uses advanced oxidation processes (AOPs), which remove organic contaminants without producing secondary waste. Objectives: The aim of this study was to develop an empirical kinetics model to predict apseudo-first order rate constant (k ap ) of sonochemical degradation of malachite green (MG). Then, this model was used to estimate the required electrical energy per order (E EO ) at various operational conditions. Materials and Methods: An ultrasonic bath with the operating frequency of 35 kHz and an output power of 170 W was used for sonochemical degradation of MG. The MG concentration was determined using a spectrophotometer at 617 nm. Results: The experimental data showed that the degradation of MG in this process obeyed pseudo-first order kinetics. Using nonlinear regression analysis a model was developed for apseudo-first order constant (k ap ) of the MG sono-degradation as a function of operational parameters, including initial concentration of MG (5 - 10 m gL -1 ), temperature (294 - 307 K), power density (0.049 - 0.163 W mL -1 ) and mechanical agitation (75 - 400 rpm), as shown in the Equation 3. Conclusions: The present research demonstrated that the ultrasonic (US) process can be utilized as an effective and simple method for treatment of MG dye in an aqueous solution. Moreover, the E EO is directly proportional to the MG concentration and power density and inversely proportional to temperature and mechanical agitation, which can be predicted by the obtained empirical kinetics model. Consequently, E EO is very sensitive to the mentioned operational parameters.