Application of modified attapulgites as adsorbents for uranyl uptake from aqueous solution-Thermodynamic approach

作者：Guerra Denis Lima^*; Silva Emiliano Mendonca; Airoldi Claudio

来源：Process Safety and Environmental Protection, 2010, 88(1): 53-61.

DOI：10.1016/j.psep.2009.10.002

• Attapulgite
• Surface properties
• Adsorption
• Calorimetry
• Thermodynamic

An attapulgite (ATPG) clay sample has been chemically modified with silylating agents N-propyldiethylenetrimethoxysilane and bis[3-(triethoxysilyl)propyl]tetrasulfide. The resulting matrices (ATPG(3TPT) and ATPG(NPTM)) have been characterized by elemental analysis, X-ray diffractometry, carbon nuclear magnetic resonance in the solid-state, and scanning electron microscopy. The natural and modified clay samples have been tested as potential adsorbents for the removal of uranyl(II) from aqueous solution at pH 2.0 and 298 +/- 1K. The maximum number of moles adsorbed was determined to be 5.55, 14.86, and 18.99 x 10(-2) mmol g(-1) for ATPG, ATPG3TPT, and ATPGNPTM, respectively. From calorimetric determinations the quantitative thermal effects for UO(2)(2+)/center interactions gave exothermic enthalpy (-6.90 to -7.88 kJ mol(-1)), negative Gibbs free energy (-22.34 to -24.56 kJ mol(-1)), and positive entropy (51.80-56.00 1 K(-1) mol(-1)). These thermodynamic data confirmed the energetically favorable condition of such interaction at the solid/liquid for all systems.

• 出版日期2010-1