Effect of pH on the Oxidation of Ferrous Ion and Immobilization Technology of Iron Hydr(oxide) in Fluidized Bed Reactor

Abstract

New, efficient, and a cheap method for the removal of ferrous ion from aqueous in a fluidized bed reactor was developed. Different from the adsorption process in the treatment of iron species, the immobilization of iron oxide on support media in a fluidized bed never reaches saturation. Furthermore, the immobilized iron oxide is reusable in catalysis and adsorption. Silica sand (Si) and iron oxide (SiG) were employed as support media to remove Fe(II) from aqueous in a fluidized bed reactor. The oxidation rate of Fe(II) and the immobilization rate of iron oxide are strongly depend on pH value so the variation of solution pH is considered to be the major parameter. Furthermore, the aeration effect on iron removal efficiency is investigated. 97% of total iron was removed at pH 8 in the presence of SiG and 87% of total iron was removed at pH 6 in the presence of Si. When the initial pH was adjusted to 6 and was not adjusted during the reactions, the optimum total iron removal efficiency (97%) was found. The air aeration was provided to keep the dissolved oxygen in constant. Aeration air accelerates the oxidation of ferrous ion, but does not improve the total iron removal efficiency.

Keywords:

• Fluidized bed reactor
• oxidation
• iron removal
• immobilization
• iron oxide

Acknowledgments

The authors would like to thank the National Science Council of the Republic of China, Taiwan, for financially supporting this research under Contract No. NSC 96‐2221‐E‐006‐022. The authors are grateful to Shiue Lin, Hu, and Hui Pin, Cheng for assistance with the surface analysis of support media.