Armaghane Danesh Bimonthly Journal (Mar 2023)
Evaluating the Efficiency of the Fenton-Ultrasonic Process in Degradation of Trihalomethanes Precursors from Aqueous Environments Using Zero Iron by Response Surface Method
Abstract
Background & aim: The presence of natural organic substances (NOM) in aqueous solutions due to the creation of disinfection by-products (DBP) including trihalomethanes (THMs) and haloacetic acids (HAAs), as a result of the chlorination of aqueous solutions in the conventional purification process and according to Potential health risks for public health have attracted a lot of attention. Therefore, the aim of the present study was to determine and investigate the performance of combined Fenton-ultrasonic processes in removing the precursors of trihalomethanes from aqueous environments using zero iron. Methods: In the present experimental study conducted in 2021, the effect of independent variables included: the initial concentration of the pollutant, the reaction time, the concentration of the catalyst used, the amount of hydrogen peroxide used and the pH in the specified range to remove the precursors of trihalomethanes from water environments using zero iron with the surface-response method based on composite design. Central (CCD) was evaluated. Experiments were designed using Design expert software and CCD-RSM method. The graphs and figures required to determine the kinetics of the reactions were drawn using Excel software and the statistical parameters were analyzed to determine the optimal conditions of the process using analysis of variance, regression and Fisher tests. Results: The results indicated that by keeping the humic acid concentration at 64.75 mg/liter and the catalyst concentration at 106.76 mg/liter and the constant pH=4.39, the highest humic acid removal efficiency occurs when It happens that the hydrogen peroxide and the reaction time are at their maximum level of 35 mmol and 88.75 minutes, respectively, and in this condition, the removal rate has increased from 80% to 92%, and also with the increase in the amount of the catalyst, the reaction efficiency increases. find According to the reactions related to the Fenton process, the presence of iron causes an increase in hydroxyl radicals, this can be one of the reasons for increasing the removal efficiency. Conclusion: In the mentioned Ultrasonic-Fenton process under laboratory conditions, iron ion as a catalyst reacted with an oxidant such as hydrogen peroxide in an acidic environment and produces hydroxyl radicals. The efficiency of this method was influenced by various factors such as pH, concentration of iron and hydrogen peroxide, initial concentration of the pollutant and reaction time.
