Decolorization Of Dyes On ACF Electrodes By Paired Electrolysis

As the most producer of dye, a lot of dye wastewater has drained to the environment. The dye wastewater widely varied quality and quantity, so it has been rather difficult to be treated. As electrochemical method is an eco-friendly technology, 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 focus on electrooxidation and electroreduction .As the core of electrochemical system, the research of electrode is an important field . Activated carbon fiber (ACF) is a kind of porous, three dimensional electrode with prospective application in dye wastewater treatment.The objective of this paper is to investigate the effect of the current density on the decolorization of anthraquinone dyes and azo dyes, such as Reactive Blue 19, Amaranth by paired electrolysis under galvanostatic model in an undivided cell. Activated carbon fiber (ACF) were used as anode and cathode respectively. The effects of current density on the decolorization kinetics, color, total organic carbon (TOC) and chemical oxygen demand (COD) removal ratio were investigated. The current density when the paired electrolysis acted were confirmed. The reaction kinetics of decolorization were simulated based on the power function. The cyclic voltammograms of ACF electrode in dye solution were measured. The energy consumptions of experimental processes were calculated.The results obtained were shown that the decolorization of dye on ACF electrodes by paired electrolysis is feasible.As for Reactive Blue 19: (1) the electrochemical behaviour of Reactive Blue 19 was irreversible;(2) in the different range of current density, the decolorization results from adsoption, electrooxidation, electroreduction and paired electrolysis;(3) in the range of 0 0.1mAcm^-2, the decolorization results from adsoption of the dye on ACF, and adsorption behavior is scarcely affected by current density;(4) in the range of 0.2⁰.6mA·cm^-2, the anodic oxidation and the cathodic adsorption of the dye play important roles in decoloration;(5) in the range of 0.7¹.0mA-cm^-2, the paired electrolysis of the dye on anode and cathode fills the roles of decolorization;(6) the decolorization reaction follows first-order kinetics;the kinetics equation was r₁ =-dc/dt = K₁i^0.8[C₀]^-0.8C₁, K₁ wasapparent rate constant which was affected by temperature;i was current density, Co was initial concentration, Ci was concentration of the dye.As for Amaranth: (1) the electrochemical behaviour of Amaranth was irreversible;(2) in the different range of current density, the decolorization results from adsoption, electrooxidation, electroreduction and paired electrolysis;(3) in the range of 0 — 0.2mAcm'2, the decolorization results from adsorption of the dye on ACF, and adsorption behavior is scarcely affected by current density;(4) in the range of 0.3⁰.4mA-cm"2, the cathodic electroreduction and the anodic adsorption of the dye play important roles in decoloration;(5) in the range of 0.5¹.0mA-cm'2, the paired electrolysis of the dye on anode and cathode fills the role of decolorization;(6) the decolorization reaction follows first-order kinetics;the kinetics equation was r2 <*-dc/dt =*K2i15[CQ]^°5C2, K2 wasapparent rate constant which was affected by temperature;/ was current density, Co was initial concentration, Ct was concentration of the dye.