Gas phase formaldehyde degradation: Continuous versus duty cycle driven plasma reactor

Abstract

This study investigated the degradation of formaldehyde (HCHO) using continuous plasma reactor (CPR) and duty cycle driven plasma reactor (DCPR) to obtain insights into reactor selection, optimization strategies, and underlying kinetics. The electrical characteristics of the reactors were analyzed via current-voltage analysis while optical properties were investigated using optical emission spectroscopy (OES). Furthermore, the reactive species concentrations were determined using gas Fourier-transform infrared (FTIR) measurements. The optimization of the degradation focused on varying the applied voltages, resulting in intensified plasma and changes in the surface temperature, electron temperature rotational temperature, and vibrational temperature. CPR demonstrated outstanding efficiency, with an energy yield of 3.60 g kW−1 h−1 and an impressive 89 % removal effectiveness at 5.8 kV. The best removal efficiency of 92 % was observed at 6.2 kV. The degradation kinetics were primarily driven by energetic electrons, along with primary reactive species such as OH ⋅ and O ⋅ with a reaction rate of 6.8 × 10−3 L J−1. This study contributes to advancing the understanding of HCHO degradation kinetics and provides practical insights into enhancing plasma-based environmental cleanup technologies without using any catalyst.