Sulphate ions removal in water through the electrocoagulation process and characterization of flocs

Author(s): Gilberto Carreño Aguilera
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Institution or organization of origin: Universidad de Guanajuato
Country: Mexico


The present research work consisted of the characterization of a multistage electrocoagulation reactor with the objective of removing sulfate ions contained in a mine water solution (7100 mg/L initial concentration of SO42-). Subsequently, the characterization of the flocs generated from the electrocoagulation process. The parameters that were studied and analyzed were mainly the applied current density and the linear velocity of the electrolyte inside the electrochemical reactor. The characterization of the multistage electrocoagulation reactor was studied in the interval between 4 j 7 mA/cm2; at speeds of 0.98 u 7.89 cm/s. It could be seen that the electrodissolution of aluminum depends on the current density. In a linear velocity interval of 0.98 u 2.90 cm/s, it was observed that the concentration of sulfate ions decreased from 7100 mg L-1 to 1700 mg L-1 (obtaining 76% removal) using a current density of 4 mA/cm2 and at a linear speed of 2.9 cm/s. However, the sulfate ion concentration could not be reduced below the official Mexican standard, so it is suggested to pass the treated water to a new electrocoagulation process. Studies have shown sulfate ion removal to be a bit tricky, especially for high initial concentrations, and may not be a suitable one-step process. The characterization of flocs obtained by EC showed that the crystalline structure allowed corroborating that the reaction mechanism between Aluminum and Sulfate ions.

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