Experimental study of the plasma chemistry in atmospheric pressure plasma contacts with dilute sulfuric acid*

Our previous study developed a gas-liquid interfacial plasma sulfonation system under atmospheric pressure conditions. During the plasma sulfonation process, droplets emit when the plasma attacks the solution surface, and some active species (•OH, HOSO2•) and long-lived species (SO2, SO3, H2O2) are generated. In this work, the gaseous elements (long-live species) were measured by the Fourier-transform infrared spectrometer (FTIR) and mass spectrometer (MS) during liquid-cathode and liquid-anode discharge. •OH generation was confirmed by optical emission spectroscopy. It is found that SO2 and some other species are only produced with droplets transmitted in the liquid-cathode discharge.