Effect of environmental parameters on the sequestration of radionickel by Mg2Al layered double hydroxide

In this work, sequestration of Ni(II) from aqueous solution to Mg2Al layered double hydroxide (Mg2Al LDH) by adsorption process as a function of various water quality parameters and temperature was investigated. The results showed that the kinetic adsorption could be described by a pseudo-second order model very well. The adsorption of Ni(II) on Mg2Al LDH was strongly dependent on pH and ionic strength. The presence of humic acid (HA)/fulvic acid (FA) enhanced the adsorption of Ni(II) on Mg2Al LDH at low pH, whereas reduced Ni(II) adsorption at high pH. The Langmuir model fitted the adsorption isotherms of Ni(II) better than the Freundlich model at three different temperatures of 298, 318 and 338 K. The thermodynamic parameters (ΔHo, ΔSo and ΔGo) calculated from the temperature dependent adsorption isotherms indicated that the adsorption process of Ni(II) on Mg2Al LDH was endothermic and spontaneous. The results show that Mg2Al LDH is a promising material for the preconcentration and separation of pollutants from large volumes of aqueous solutions.