A study of the potential application of nano-Mg(OH)2 in adsorbing low concentrations of uranyl tricarbonate from water

Abstract

This work aims at the investigation of nano-Mg(OH)₂ as a promising adsorbent for uranium recovery from water. Systematic analysis including the uranium adsorption isotherm, the kinetics and the thermodynamics of adsorption of low concentrations of uranyl tricarbonate (0.1–20 mg L⁻¹) by nano-Mg(OH)₂ was carried out. The results showed a spontaneous and exothermic uranium adsorption process by Mg(OH)₂, which could be well described with pseudo second order kinetics. Surface site calculation and zeta potential measurement further demonstrated that UO₂(CO₃)₃⁴⁻ was a monolayer adsorbed onto nano-Mg(OH)₂ by electrostatic forces. Accordingly, the adsorption behavior met the conditions of the Langmuir isotherm. Moreover, in most of the reported literature, nano-Mg(OH)₂ had a higher UO₂(CO₃)₃⁴⁻ adsorption affinity b, which implied a higher adsorption amount at equilibrium in a dilute adsorbate system. The significance of the adsorption affinity b for choosing and designing adsorbents with respect to low concentration of resources/pollutants treatment has also been assessed.