Adsorption of Zinc in Aqueous Solution onto Natural Maghnite Modified by 3-Aminopropyltriethoxysilane
Abstract
Zinc (II) was immobilised directly onto clay, maghnite (M13), and after their amine functionalisation with (3-aminopropyl)triethoxysilane (APTES). The APTES-functionalised maghnite (MS) showed higher zinc loading than only maghnite, indicating that the clay functionalisation enhanced the Zn(II) removal. The hydrophilic properties of the clay surface have been modified, but not turned into hydrophobic ones. The graft has indeed a polar amine group and the chain length is too short to present an important hydrophobic character. X-ray diffraction indicated that their original structure had been preserved. This new hybrid organic–inorganic material may be a good alternative for separation and pre-concentration of heavy metal ions. Both adsorbents were characterised by FTIR, XRD, TG and SEM. Both adsorbents showed maximum adsorption of the metal ions at pH 6.1 for Mag and pH 9 for MS. The adsorption processes followed pseudo-second-order kinetics. The Langmuir model best fits the adsorption data.
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