This study evaluated the adsorption capacity of hydrotalcite material (HT) for the removal of Mn2+in an aqueous solution. Factors affecting the adsorption capacity of HT for the removal of Mn2 ions from aqueous solutions, such as initial pH, contact time and initial Mn2 concentration, were investigated using batch experiments. | JOURNAL OF SCIENCE OF HNUE DOI Chemical and Biological Sci. 2015 Vol. 60 No. 9 pp. 51-58 This paper is available online at http THE REMOVAL OF Mn2 IONS IN AQUEOUS SOLUTION USING HYDROTALCITE MATERIAL Pham Thi Hanh and Ly Bich Thuy School of Environmental Science and Technology Hanoi University of Science and Technology Abstract. This study evaluated the adsorption capacity of hydrotalcite material HT for the removal of Mn2 in an aqueous solution. Factors affecting the adsorption capacity of HT for the removal of Mn2 ions from aqueous solutions such as initial pH contact time and initial Mn2 concentration were investigated using batch experiments. This study made use of pseudo-first-order and pseudo-second-order kinetic models. Langmuir and Freundlich adsorption isotherms were investigated. The obtained results show that HT removes Mn2 effectively gt 97 at a temperature of 25 oC when the solid liquid ratio is and the initial Mn2 concentration is 5 mg L. The pseudo-second-order model fit the observed data better than the pseudo-first-order model. The equilibrium data correlated very well with the Freundlich isotherm model which implies multilayer adsorption. The obtained results suggested that HT is a good adsorbent for removal of Mn2 ions in aqueous solution. Key words Hydrotalcite material Mn2 removal. 1. Introduction Manganese is usually present in groundwater as a divalent ion Mn2 and it is considered to be a groundwater contaminant in several areas of the Red and Mekong River deltas 1 2 . Manganese removal is a matter of concern because groundwater is the main water source of drinking water in Vietnam especially in rural areas. Almost every rural household in Vietnam uses sand filtration which removes many impurities from the groundwater. However many studies have shown that after sand filtration the manganese level in the water exceeds the maximum amount for drinking water as recommended by both the World .