Role of ionic surfactants on the activation of K2S2O8 for the advanced oxidation processes

Effects of cetyltrimethylammonium bromide (CTAB) and sodium dodecylsulfate were studied to eluci-date the persulfate based in-situ chemical oxidation of subsurface contamination. Advanced oxidation processes (AOP) utilizing Fenton's like reagent was investigated for the degradation of acid orange 7 (AO7) with and without ionic surfactants. The new findings are that the CTAB and SDS retarding the S2O82-activation to some extent. The kinetics of S2O82-assisted decomposition of AO7 were performed under different reaction parameters such as [S2O82-], [Fe2+], [AO7], pH, and temperature. The rate con-stants (kw) were decreased markedly in presence of both surfactants. CTAB showed the most potential deactivation than that of SDS. The stability of both surfactants were determined in presence of S2O82-, and no drastic changes was observed in the critical micellar concentration (CMC). The columbic attrac-tion and repulsion between the reactants (S2O82-, and AO7) with ionic head groups of CTAB and SDS are responsible to deactivating the S2O82-decomposition. AO7 and S2O82-, respectively, solubilized and transferred from bulk phase to micellar surface through electrostatic interactions, which may con-tribute to the inhibitory role of CTAB micelles in the AOP of AO7. Finally the role of surfactants in the Fenton's like oxidation of AO7 based on the micellar-pseudo phase model was proposed and discussed.(c) 2022 Elsevier B.V. All rights reserved.

Automated summary

The effects of cetyltrimethylammonium bromide (CTAB) and sodium dodecylsulfate (SDS) on the persulfate-based in-situ chemical oxidation were investigated. Both surfactants were found to retard the activation of S2O82-. The degradation rate of acid orange 7 (AO7) was significantly reduced in the presence of CTAB and SDS, with CTAB showing a stronger deactivation effect. The inhibitory role of CTAB micelles in the AO7 advanced oxidation process (AOP) was proposed based on the micellar-pseudo phase model.