Table of Contents
ISRN Chemical Engineering
Volume 2012, Article ID 740429, 8 pages
http://dx.doi.org/10.5402/2012/740429
Research Article

Degradation Kinetics of Fe-EDTA in Hydrogen Sulfide Removal Process

Pollutant Treatment Technology Research Unit, Department of Chemical Engineering, Faculty of Engineering, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand

Received 26 January 2012; Accepted 26 February 2012

Academic Editors: C. Chen and H. Domínguez

Copyright © 2012 R. Saelee and C. Bunyakan. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Available data on the degradation of Fe-EDTA liquid redox H2S removal processes are reviewed, and the effect of H2S molar flow rate, the initial concentration of Fe(III)EDTA, and the presence of sodium citrate in Fe-EDTA solution were investigated in this study. The semibatch with continuous flow of H2S containing biogas was used under a wide range of experimental conditions; p H = 7 . 0 , H2S molar flow rate, 𝑄 H 2 S (1.08 × 10−3–3.40 × 10−3 mol/h), the initial concentration of Fe(III)EDTA, 𝐶 F e , 0 (2.17–8.16 mol/m3), and the concentration of sodium citrate, 𝐶 C I (0–300 mol/m3). The result showed that sodium citrate acted as stabilizer with a good ability to reduce the degradation rate. The degradation rate of Fe-EDTA was found to follow pseudo first-order kinetics. Empirical correlations expressed the degradation rate constant as a function of significant H2S molar flow rate, and the initial Fe(III)EDTA and sodium citrate concentration were successfully developed for the prediction of Fe-EDTA degradation rate. Moreover, the precipitated solid, called sulfur cake, was recovered, and its composition was investigated. The result revealed that the sulfur cake contained more than 98% sulfur element and almost balances with iron, and no significant EDTA was degraded into the solid form.