Effect of current density and pH on the electrochemically generated active chloro species for the rapid mineralization of p-substituted phenol. (July 2021) - Qiao, Qicheng
Abstract: The aim of present study is increasing the degradation and mineralization of 4-chlorophenol (4-CP) during electrochemical oxidation with Ti/RuO2 anodes. Innovatively, the evolution of chlorine-related species and the formations of various inorganic ions were investigated by electrolytic analysis in order to set up whether the formation and consumption of these byproducts associated with either chemical or electrochemical reactions. The effect of operating parameters such as current density, solution pH, treatment time, and electrolyte concentration has been studied. The formation of Cl2, chlorite (ClO2 − ), and chlorate (ClO3 − ) were detected by adding the known concentration of Cl − ions at different pH and current densities. Concentration trends of active chloro-species indicate that the degradation of 4-CP and chemical oxygen demand (COD) removal was formed maximum at pH 6 and j of 225.2 Am −2 in presence of 0.0085 M NaCl. Thus, the 4-CP degradation mainly depends on the radicals and active chlorine formation and a mineralization mechanism was proposed based on intermediates byproducts formation such as catechol, hydroquinone, 1, 4-benzoquinone, and organic acids identify by using the GC-MS and HPLC analysis at the optimum treatment condition. Total organic carbon (TOC) at different pH and current density, mass balance analysis of carbon and inorganic species formation were determined at the optimum treatment conditions of 4-CP. The degradation kinetic of 4-CP was followed the pseudo-first order kinetic model during the each parameters optimization. Specific energy consumption and current efficiency were also used to identify the technical feasibility of the process. Graphical abstract: Image 1 Highlights: Electro-oxidation of 4-chlorophenol (4-CP) with Ti/RuO2 anodes. Effect of pH and current density on active chloro-species formation. GC-MS, HPLC, IC and mass balance analysis were used to propose the mineralization mechanism. Synergistic effect of active chloro-species and OH promotes the 4-CP oxidation.