Sequential gas-liquid treatment for gaseous toluene degradation by Fenton’s oxidation in bubble reactors

• Published in: Journal of environmental chemical engineering Vol. 8; no. 3; p. 103796
• Main Authors: Lima, Vanessa N., Rodrigues, Carmen S.D., Madeira, Luís M.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.06.2020
• Subjects: Bubble column reactor; Bubble reactor; Fenton oxidation; Sequential gas-liquid treatment; Toluene degradation; Sequential gas-liquid treatment; Bubble reactor; Toluene degradation; Bubble column reactor; Fenton oxidation
• ISSN: 2213-3437; 2213-3437
• DOI: 10.1016/j.jece.2020.103796

[Display omitted] •Toluene treatment by the Fenton’s process was optimized in a bubbling reactor.•Absorption + oxidation promotes further toluene absorption.•The liquid treatment stage increased the effluent mineralization and biodegradability.•A process scale-up was implemented in a bubbling column reactor.•Several sequential gas-liquid treatment stages were succefully implemented. A lab scale bubble reactor (BR) configuration was employed to evaluate the degradation of gaseous toluene by Fenton’s oxidation under semi-batch mode operation (i.e., with continuous gas bubbling in the liquid phase where organics oxidation is carried out). A parametric study was performed for evaluating the effect of Fenton’s process operating parameters, such as temperature and concentration of Fe2+ and H2O2, in the removal of toluene from the gas stream. The maximum amount of toluene transferred (0.041 mol per liter of solution) was reached when the optimal conditions ([Fe2+] = 2.5 mM, [H2O2] = 20 mM, and T = 25 ºC, at pH 3.0) were used after 120 min of reaction, yielding the highest average toluene absorption rate (5.78 × 10−6 mol/L.s). The treatment of the gas stream increased, however, the organic load in the aqueous phase, so a subsequent treatment stage of the liquid was performed. Additionally, a scale-up of the sequential gas-liquid treatment for a bubble column reactor (BCR) was carried out for several cycles, up to almost 20 h. This strategy, making use of the Fenton’s process for treating the toluene gas stream, with intermediate liquid oxidation, allowed to reach more gas treatment stages, while providing a final effluent that is non-toxic (0.0 % of inhibition of Vibrio Fischeri) and biodegradable.