Author(s)

Jihyun R. Kim, Branden Santiano, Hyosang Kim, Eunsung Kan

Department of Molecular Bioscience and Bioengineering, University of Hawaii at Manoa, Honolulu, USA.

The present study aims to develop effective adsorption and oxidation of synthetic dye in wastewater by using the newly synthesized iron-amended activated carbon. Recently synthetic dye-containing wastewater has gained more attention due to its mass discharge, high toxicity and low biodegradation. For enhancing adsorption of dye and oxidative regeneration of dye-exhausted activated carbon, the novel amendment of iron-deposited granular activated carbon (GAC) was developed. It was to amend ferrous ion onto the acid-pretreated GAC when pH of iron solution was higher than the pH at point of zero charge (pH, _pzc) of the GAC. Methylene blue (MB) in water was adsorbed onto the acid-treated iron- amended GAC (Fe-GAC) followed by single or multiple applications of H₂O₂. Batch experiments were carried out to study the adsorption isotherm and kinetics indicating adsorption of MB onto the Fe-GAC followed Langmuir isotherm and the pseudo-second order kinetics. The Fe-GACshowed the maximum adsorption capacity (q_m) of 238.1 ± 0.78 mg/g which was higher than the virgin GAC with q_m of 175.4 ± 13.6 mg/g at 20?C, pH 6 and the initial concentration of 20 - 200 mg/L. The heterogeneous Fenton oxidation of MB in the Fe-GAC revealedthat increasing the H₂O₂ loading from 7 to 140 mmol H₂O₂/mmol MB led to enhancing the oxidation efficiency of MB in the GAC from 62.6% to 100% due to the increased generation of hydroxyl radicals. Further enhancement of oxidation of MB in the Fe-GAC was made by the multiple application of H₂O₂ while minimizing OH radical scavenging often occurring at high concentration of H₂O₂. Therefore, the acid-treated iron-amended GAC would provide excellent adsorption capacity for MB and high oxidation efficiency of MB in the GAC with multiple applications of H₂O₂ and optimum iron loading.

Adsorption; Activated Carbon; Iron-Amended Activated Carbon; Heterogeneous Oxidation; Fenton Oxidation; Methylene Blue

J. Kim, B. Santiano, H. Kim and E. Kan, "Heterogeneous Oxidation of Methylene Blue with Surface-Modified Iron-Amended Activated Carbon," American Journal of Analytical Chemistry, Vol. 4 No. 7A, 2013, pp. 115-122. doi: 10.4236/ajac.2013.47A016.