title: Layer silicates modified with 1,4-bis(3-aminopropyl)piperazine for the removal of Th(IV), U(VI) and Eu(III) from aqueous media.
abstract: Natural montmorillonite (M) and synthetic kanemite (K) have been functionalized with 1,4-bis(3-aminopropyl)piperazine reacted with methylacrylate to yield new inorganic-organic chelating materials. The original and modified materials were characterized by X-ray diffractometry, textural analysis, SEM and nuclear magnetic nuclei of carbon-13 and silicon-29. The chemically modified clay samples (M-APPMA and K-APPMA) showed modification of its physical-chemical properties including: specific area 45.0m(2)g(-1) (M) to 978.8 m(2)g(-1) (M-APPMA) and 23.5m(2)g(-1) (K) to 898.9 m(2)g(-1) (K-APPMA). The ability of these materials to remove thorium(IV), uranyl(VI) and europium(III) from aqueous solution was followed by a series of adsorption isotherms, which were fitted to non-linear Sips adsorption isotherm model. To achieve the best adsorption conditions the influence of pH and variation of metal concentration were investigated. The energetic effects (Delta(int)H degrees , Delta(int)G degrees and Delta(int)S degrees ) caused by metal ions adsorption were determined through calorimetric titrations.
authors: Chemistry Institute, State University of Campinas, 13084-971 Campinas, São Paulo, Brazil. dlguerra@iqm.unicamp.br
authors: Denis L
authors: DL
authors: Guerra
authors: Alane A
authors: AA
authors: Pinto
authors: Rúbia R
authors: RR
authors: Viana
authors: Claudio
authors: C
authors: Airoldi
mesh_terms: D000327:Adsorption; D001546:Bentonite / Q000737:chemistry; D002151:Calorimetry / Q000379:methods; D002244:Carbon / Q000737:chemistry; D005063:Europium / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007477:Ions; D009682:Magnetic Resonance Spectroscopy; D008855:Microscopy, Electron, Scanning / Q000379:methods; D010879:Piperazines / Q000737:chemistry*; D012825:Silicon / Q000737:chemistry*; D013816:Thermodynamics; D013910:Thorium / Q000737:chemistry*; D014501:Uranium / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D007477:Ions; D010879:Piperazines; D001546:Bentonite; D005063:Europium; D014501:Uranium; D013910:Thorium; D002244:Carbon; C486841:1,4-bis(3-aminopropyl)piperazine; D012825:Silicon