ADSORPTION OF ACETIC ACID AND THE PROMOTERS OF FORMATION OF PEROXO GROUPS ON PLATINUM AT HIGH ANODIC POTENTIALS

Abstract

Introduction. Peroxyacetic acid is a strong disinfectant with a wide spectrum of antimicrobial activity. The advantages of peroxyacetic acid are: no stable toxic derivates, the dependence on pH is unsignificant, efficiency and contact time are nondurable. Peroxyacetic acid is produced on an industrial scale by chemical synthesis. The output product requires specific storage conditions. Electrochemical methods of synthesis of peroxyacetic acid are divided into two directions: 1) production of РАА by the cathodic generation of hydrogen peroxide with the presence of acetic acid; 2) production peroxyacetic acid through the anodic oxidation. The advantages of electrochemical synthesis are production of peroxyacetic acid directly “in situ” and synthesis of diluted peroxyacetic acid and acetic acid. The problem of understanding and managing the process of peroxyacetic acid electrochemical synthesis poses the problem of obtaining new data on the component-solution adsorption in the region of high anodic potentials. The aim: to investigate the adsorption of acetic acid and promoters of the formation of peroxo groups on platinum at high anodic potentials. Research methods. The adsorption of acetic acid and peroxo group formation promoters was studied using the charging curves method on the surface of a Pt/PtO electrode. Results. It is shown that the potential shift to the electropositive region leads to a continuous increase in the adsorption of acetic acid along with an increase in the charge of the platinum surface. It is shown that when the electrode potential shifts to the electropositive region, the adsorption of Cl–, Br– and I– ions increases continuously with increasing platinum surface charge. It is shown that the dependence of the adsorption of CNS– ions on the potential has a maximum at ≈ 1.85 V. A further decrease in the adsorption of CNS– ions is associated with a stronger adsorption of their oxidation product – CN–. It has been established that, by the effect on the electrode surface, anions are placed in the CNS– > Cl– > Br– > I– series. Cl–, Br– and I– additives should be used for the electrochemical synthesis of peroxyacetic acid. They contribute to an increase in the current efficiency of the target product in comparison with the initial solution. CNS– additive is not effective. This is explained by the specific adsorption of CNS– ions on the surface of a platinum electrode.