Formation of fluorine for abating sulfur hexafluoride in an atmospheric-pressure plasma environment

In this study, a large amount of toxic and reactive fluorine (F(2)) was produced in the atmospheric-pressure microwave discharge environment by adding additives to abate sulfur hexafluoride (SF(6)). When H(2) was added, the selectivity of F(2) was as high as 89.7% at inlet H(2)/SF(6) molar ratio (R(H2)) = 1. Moreover, the conversion of SF(6) significantly increased from 33.7% (without additive) to 97.7% (R(H2) = 5) at [SF(6)]=1%, and 0.8 kW because the addition of H(2) inhibited the recombination of SF(6). With the addition of O(2), H(2)+O(2) or H(2)O, the selectivity of F(2) was still greater than 81.2%, though toxic byproducts, including SO(2)F(2), SOF(2), SOF(4), SO(2), NO, and HF, were detected. From optical emission spectra, SF(2) was identified, revealing the SF(6) dissociation process might be carried out rapidly through an electron impaction reaction: SF(6)-->SF(2)+4F. Subsequently, F(2) was formed via the recombination of F atoms.