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Central composite design with response surface methodology was applied to optimize the main experimental parameters such as current, time, As(III) concentration, and hardness for arsenic (III) removal in hard water by the electrocoagulation process. The main aim was to find the optimum process parameters to maximize arsenic removal from the mathematical model equations developed in this study using R software. By variance and regression analysis, the linear regression equation was established as a predicted model. The R2 of 0.93 indicated that the equation was well fitted. The optimum condition of 99% of As(III) removal for current (A), time (min), As(III) concentration (ppb), and hardness (mg/L as CaCO3) is 0.07, 37, 274, and 324, respectively. ANOVA analysis shows no significant difference between the observed and predicted values (p-value > 0.05) which shows good fit to the model.

The oxidation of Acid Green 50 (AG50) textile dye using Fe2O3–Al2O3, prepared from the calcination of FeIII–Al(OH)4-gel, as a highly active catalyst in the heterogeneous Fenton oxidation process was studied. It was found that the ferric ions loaded on the surface of neutral Al(OH)4− gel and then calcined at different temperatures is an efficient catalyst in the heterogeneous Fenton reaction for the mineralization of aqueous AG50. According to the X-ray analysis, the iron catalyst is a mix of Fe2O3 and Al2O3. The thermal treatment gives long-term stability to the catalyst because it minimizes iron leaching from the catalyst. The catalyst was used in four successive recycling heterogeneous Fenton oxidations generating a colorless solution with the removal of over 95% of total organic carbon (TOC) in 90 min. This shows that the Fe2O3–Al2O3 catalyst is highly efficient for the degradation of AG50 after being used in several cycles during the dye treatment. It was also found that the degradation of AG5...

The removal of total organic carbon (TOC) from wastewater generated from phenolformaldehyde resin manufacturing industry using the electrocoagulation process was studied in this paper. Experiments were carried out at current densities of 5.0, 7.5 and 10.0 mA/cm2 using iron electrodes connected in parallel arrangement in an undivided electrochemical reactor. TOC content was determined during the different stages of electrolysis in order to know the feasibility of the electrocoagulation treatment for highly concentrated bio-refractory organic pollutants present in the industrial wastewater. Different operational conditions such as pH, time, and electrical conductivity were studied for TOC removal. Experimental values indicated that the electrocoagulation process showed high TOC removal efficiencies, 78.7% within 60 min of electrolysis, with an initial concentration of 23.8 × 103 mg/l TOC. Thus, these results showed that the electrocoagulation process is effective for the removal of initially high T...