Removal of metal ions from aqueous solution by chelating polymeric hydrogel |
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Authors: | Hudson Wallace Pereira Carvalho Ana P L Batista Peter Hammer Gustavo H P Luz Teodorico C Ramalho |
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Institution: | 1.Departamento de Fisco-Química do Instituto de Química da,Universidade Estadual Paulista,Araraquara,Brazil;2.Departamento de Química Fundamental do Instituo de Química da,Universidade de S?o Paulo,S?o Paulo,Brazil;3.Departamento de Química da,Universidade Federal de Lavras,Lavras,Brazil |
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Abstract: | Polysaccharide natural seed coat from the tree Magonia pubescens, in the form of hydrogel was used to remove metals in aqueous solution. Swelling tests indicate that seed coat presents hydrogel
behavior, with maximum water absorption of 292 g water/g. Adsorption experiments performed using Na+, Mg2+, K+, Ca2+, Cr3+, Fe3+ and Zn2+ demonstrated that the polysaccharide structure has a high capacity to extract these ions from the aqueous solution. Scanning
electron microscopy revealed significant morphological changes of the material before and after water contact. Differential
scanning calorimetry measurements indicate a signal shift of the water evaporation temperature in the material with adsorbed
zinc. X-ray photoelectron spectroscopy analysis combined with theoretical studies by the density functional theory and on
Hartree–Fock (HF) level evidence that the metallic ions were adsorbed through coordination with hydroxyl groups of polysaccharide.
In the case of Zn2+ the lowest HF energy was observed for the tetracoordination mode, where Zn2+ is coordinated by two hydroxyl groups and two water molecules. |
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