Effects of voltage, frequency, and pulse parameters on mercury oxidation efficiency in pulsed corona discharge

Abstract

Plasma-based methods for Hg removal exhibit advantages such as low cost and environmental friendliness. A nanosecond-pulse-driven corona discharge single-cylinder system was established to study the effects of discharge parameters—voltage, frequency, pulse width, and rise time—on the oxidation efficiency of Hg. The oxidation efficiency of Hg was calculated by measuring the Hg⁰ concentration using a cold vapor atomic absorption spectrometer (CVAAS), while the voltage and current of the corona discharge were measured via a high-voltage probe and a current coil to calculate the power density. The experimental results indicated that the oxidation rate of Hg⁰ was positively correlated with the voltage, frequency, and pulse width of the power source in the tested ranges, but not with the rising edge. The most important parameter is the energy density in the discharge plasma, which increases with voltage, frequency, and pulse width, showing a logarithmic-exponential function between the oxidation rate and energy density. An Hg⁰ removal rate of 90 % or more can be reached when the energy density is more than 9.81 J/L and a maximum rate of 97.84 % can be achieved under voltage of 15.1 kV, frequency of 200 Hz and pulse width of 200ns in the current work. The findings of this research are helpful in the design of a pulsed corona discharge system for the removal of Hg⁰ pollutants.