Plasma-Degradation of Dinitrophenols and Interpretation by the Molecular Orbital Theory

Abstract

The advanced oxidation of 2, 4-dinitrophenol (DNP), 2, 5-DNP, and 3, 4-DNP in aqueous solution has been investigated using a multi-gas, dielectric barrier discharge, and the degradation was measured by high performance liquid chromatography (HPLC). The acceleration of the advanced-oxidation has been investigated by the combination of the anion exchange polymer. The degradation pathway was suggested involving a rapid detachment of the nitro group followed by a slow opening of the aromatic-ring. The hydroxyl radical and the excited hydroxyl anion are responsible for the primary attack of the DNP with the production of dihydroxynitrobenzenes. The attack of hydroxyl radical occurs at the benzene ring carbon activated by the presence of a phenolic OH group and a nitro group. The reaction is dominated by a pseudo-first order kinetic reaction. The degradation process is interpreted using Molecular Orbital Theory.

Comparison of the Degradation Efficiency of Dinitrophenols in Dielectric Barrier Discharge at Gas/Liquid Boundary

“…Working gas is supplied by a piezo-flow controller. To maintain the reproducible control of the discharge, as in Table 1, the apparatus of the same geometry is used in a series of experiment [6][7][8]. The discharge is excited with a quasi-sinusoidal high voltage generated by a fly-back transformer-type oscillator (Fig.…”

“…The plasma-degradation of the aromatic compound is in several forms: the pulse-streamer discharge and direct current contact glow discharge [3,4], high intensity UV radiation [5]. In recent works, the decomposition of aromatic compound was reported in multi-gas compact dielectric barrier discharge 2, 6-dibromophenol (DBP) [6] and the experimental discovery of the plasma degradation of 2, 4 -DNP , 2, 5 -DNP, and 3,4 -DNP [7,8]. New in this work, we discuss the mechanism of the enhanced efficiency of the plasmadegradation in the case of 2, 5 -DNP compared with the case of 2, 4 -DNP on the basis of the molecular orbital theory.…”