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In recent years, among the various treatment methods, the electrocoagulation process has been used for the treatment of effluents containing various dye pollutants. Sunset yellow (S.Y.) azo dye is one of the common food colors widely used in various food industries. This study investigated the removal of the dye S.Y. from aqueous media by the electrocoagulation method in an electrochemical reactor using concentric iron electrodes. The experiments were designed by the Response Surface Method (RSM) with the help of the Minitab software in such a way that the effect of various process-influencing parameters, such as current density, electrolysis time, electrolyte concentration, pH of the solution, and the effluent flow rate, on the desired pollutant removal efficiency was investigated. According to the results of the process optimization by RSM, the optimal conditions for the process were obtained as follows: pH of 10, current density of 2.65 mA/cm2, electrolysis time of 42.32 min, initial dye concentration of 20 mg/L, and effluent flow rate of 2.5 L/min. Under the above optimal conditions, the efficiency of dye removal was more than 99%.

Different types of the dye are considered as the major environmental pollutants, and even their very low concentration can affect the transparency and aesthetic quality of the surface waters. Acid Red 1 (AR1) is one of the synthetic azo dyes extensively used in textile industries. The present study aims to examine the efficiency of electrocoagulation method on the removal of AR1 from contaminated waters in a recirculating tubular reactor using iron electrodes. Numerous parameters such as current density, pH, electrolyte concentration, flow rate, and the concentration of dye pollutants were studied. The obtained spectrophotometric results indicated that with an increase in current density and electrolyte concentration, the percentage of dye removal increases, but with an increase in dye concentration, pH, and the flow rate of solution into the reactor, the rate of pollutant removal decreases. For 2 litters of the solution containing 30 mg/L AR1 with a current density of 0.011 A/cm2, pH of 6.8, electrolysis time of 20 minutes, flow rate of 45.45 ml/s, and electrolyte concentration of 0.08 g/L, dye removal percentage of about 95% was obtained by electrocoagulation in a recirculating tubular reactor.

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