Surface acid chemistry associated with dielectric barrier discharge (DBD) treatment of polyethylene

Abstract

The chemistry associated with atmospheric dielectric barrier discharges (DBDs) in air has been studied. Laboratory and industrial DBD systems have been investigated. In this work, we have emphasized the use of aqueous extractions of treated surfaces, followed by analyses by ion chromatography to study the DBD chemistry. A range of DBD factors including dose, humidity, airflow and electrode configuration (one versus two dielectric barriers) is found to influence the levels of acids, notably nitrous, nitric and oxalic acids, on the treated surfaces. A mechanistic rationale involving the primary formation of the nitrous and nitric acids in the gas phase is proposed.

Chemical Reactivity of Discharges and Temporal Post-Discharges in Plasma Treatment of Aqueous Media: Examples of Gliding Discharge Treated Solutions

“…The acidic effect was first evidenced and carefully studied by Moussa et al, , because of its key importance in the control of almost all the organic oxidation−reduction reactions . The study was extensively completed with the behavior of efficient acidity buffers, the pH of which decreased by 0.2 pH units only for 1 h of exposure to the discharge, which enables one to achieve many plasma treatments at stabilized pH.…”

“…It is well-known now that the acidity of an aqueous target exposed to an electric discharge in air increases (pH decreases) and that matching ions (i.e., mainly NO 2 − and NO 3 − ) enter the liquid phase, so that they induce an enhanced conductivity of the solution. The formation of nitrous/nitric acids is not limited to the treatment of solutions, because a DBD treatment of polyethylene in humid air reports indicates their presence. Those authors suggested the occurrence of an equilibrium.…”

“…Representative reactions of each type have been identified in aqueous targets. [69][70][71] 4.3.1. The Acid Effect.…”

“…and NO 3 -) enter the liquid phase, so that they induce an enhanced conductivity of the solution. The formation of nitrous/ nitric acids is not limited to the treatment of solutions, because a DBD treatment of polyethylene in humid air reports 71 indicates their presence. Those authors 71 suggested the occurrence of an equilibrium.…”

“…The formation of nitrous/ nitric acids is not limited to the treatment of solutions, because a DBD treatment of polyethylene in humid air reports 71 indicates their presence. Those authors 71 suggested the occurrence of an equilibrium. Therefore, their model involves a three-body reaction as an elementary step and the occurrence of N 2 O 5 , which has not been proven experimentally.…”