Potentiostatic And Galvanostatic Amaranth On Acf Electrochemical Decolorization

Dye wastewater is characterized by complicated components, strong color, highly fluctuating pH, high COD, TOC concentration and suspend solids, low biodegradability, and widely varied quality and quantity, so it has been rather difficult to treat dye wastewater. As an eco-friendly technology, electrochemical method added little or no additional chemicals without secondary pollutants for wastewater treatment. In recent years, there has been increasing interest in the use of electrochemical methods for the treatment of dye wastewater.Most study on dye wastewater treatment with electrochemical method was conducted with cell voltage or current constantly controlled and the parameters of voltage, current density, wastewater conductivity, pH, current efficiency and energy consumption were evaluated. However, there are few reports on the relationship between the decolorization and the potential and current density. It is known that potential and current density are the fundamental factors for the electrochemical process. So it is necessary and important to evaluate the effect of potential and current density on the decolorization of dye wastewater. Besides, a great number of experiments were performed in a single compartment electrolytic cell. As a result, it is difficult to make sure the pure contribution of electrooxidation and electroreduction for the decolorization of dye wastewater because of the cross- interference of the anode and cathode.The objective of this study is to estimate an experimental model for the investigation of the effect of the potential and current density on the decolorization of dye wastewater. Activated carbon fiber (ACF) was used as anode or cathode under potentiostatic and galvanostatic model, respectively. Amaranth, a kind of azo dye, was chosen as the model compound. The electrolytic cell was designed as a two-compartment cell separated by cation selective membrane. The effect of potential and current density on the decolorization kinetics, color, total organic carbon (TOC) and chemical oxygen demand (CODcr) removal ratio were analyzed.The results obtained were shown as: (1) The Amaranth water was oxidized on ACF at the potential of 0.6V and reduced at the potential of -0.2V. (2) In the range of -0.1V~0.5V and -0.813 mA/cm2~0.0625 mA/cm2, the decolorization results from the adsorption of Amaranth on ACF and the adsorption behavior is insignificantly affected by electric polarization; (3) In the range of -0.2V~-0.8V and -0.844 mA/cm2~-1.13 mA/cm2, the electroreduction plays an important role in the decolorization.Furthermore, the decoloring process follows pseudo-first order kinetics; (4) In the range of 0.6V~1.4V and 0.125 mA/cm2~0.5 mA/cm2, the electrooxidation results in the decolorization and the decoloring process also follows pseudo-first order kinetics.