Nanosized centers for mercury(II) ions adsorption on a surface of modified silica

Abstract

The present work investigates the adsorptive interactions of Hg(II) ions in aqueous medium with hydroxylated silica, aminopropylsilica and silica chemically modified by β-cyclodextrin. Batch adsorption studies were carried out with various agitation times and mercury(II) concentrations. The maximum adsorption was observed within 15-30 min of agitation. The kinetics of the interactions, tested with the model of Lagergren for pseudo-first and pseudo-second order equations, showed better agreement with first order kinetics (k1 = 3.4 ± 0.2 to 5.9 ± 0.3 min-1). The adsorption data gave good fits with Langmuir isotherms. The results have shown that β-cyclodextrin-containing adsorbent has the largest adsorption specificity to Hg(II): KL = 4125 ± 205 mmol-1. "β-cyclodextrin-NO3-" inclusion complexes with ratio 1: 1 and super molecules with composition C42H70O35 · 3 Hg(NO3)2 are formed on the surface of β-cyclodextrin-containing silica. © Versita Warsaw and Springer-Verlag Berlin Heidelberg 2008.