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Synthesis of Fe-MCM-41 with highly ordered mesoporous structure and high iron content and its adsorption isotherms of arsenate and arsenite

In the present paper, the synthesis of Fe-MCM-41 with high iron content and highly ordered mesoporous structure was performed. The adsorption isotherms of As(III) and As(V) over Fe-MCM-41 were also presented. | JOURNAL OF SCIENCE, Hue University, Vol. 69, No. 6, 2011 SYNTHESIS OF Fe-MCM-41 WITH HIGHLY ORDERED MESOPOROUS STRUCTURE AND HIGH IRON CONTENT AND ITS ADSORPTION ISOTHERMS OF ARSENATE AND ARSENITE Le Thanh Son1 and Dinh Quang Khieu2 1 2 Hue University College of Sciences, Hue University Abstract. In this paper, the synthesis of iron containing MCM-41 material (Fe-MCM-41) and its adsorption isotherms were investigated. Fe-MCM-41 materials were synthesized by direct process using K2[Fe(CN)6] or iron oxalate as iron source. The materials obtained were characterized by XRD, adsorption/desorption isotherms of nitrogen. The results showed that using K2[Fe(CN)6] as an iron source can provide Fe-MCM-41 with highly ordered mesoporous structure and high iron content with molar ratio of Si/Fe around 10. The isotherm study showed that the prepared Fe-MCM-41 sample exhibited high adsorption activity towards As(III) as well as As(V). The experimental data of adsorption of As(III) and As(V) onto Fe-MCM-41 followed the Langmuir models. The maximum monolayer adsorption capacities based on this model were 25.4 and 37.2 mg/g for As(III) and As(V), respectively. 1 Introduction Arsenic is a highly toxic chemical constituent thereby posing epidemiological problems to human health. Serious arsenic pollution has been observed not only in various mineral and chemical processes but also in some sources of ground water. Most common arsenic species found in aqueous media are anionic species of arsenate and arsenite which exist as oxoanions [1]. Arsenic has been removed by the following processes: precipitation with lime, co-precipitation with ferric sulfate, alum precipitation and precipitation as the sulfide using either sodium sulfide or hydrogen sulfide. As there is no simple treatment for the efficient removal of arsentate (III), an oxidation step is necessary to provide acceptable results in arsenic elimination [2]. Driehaus et al [3] reported the use of manganese dioxide as .