Natural Aluminosilicates Modified with Organosilicon Thiosemicarbazides for the Extraction of Nickel(II) Ions

Abstract

Modified adsorbents are obtained by the immobilization of 1-(3-triethoxysilylpropyl)thiosemicarbazide (TSC), 1-(3-triethoxysilylpropyl)-1-phenylthiosemicarbazide (1-FTSC), and 3-1-(3-triethoxysilylpropyl)-4-phenylthiosemicarbazide (4-FTSC) on the surface of natural microporous aluminosilicates (ASs). The morphology and elemental composition of the surface of the modified ASs are studied by scanning electron microscopy (SEM) and analysis of energy-dispersive X-ray spectra (EDXSs). The degree of silanization of ASs is determined by the structure of organosilicon thiosemicarbazides and decreases in the series AS–TSC > AS–4-FTSC > AS–1-FTSC. The presence of characteristic for TSC, 1-FTSC, and 4-FTSC structural groups in the composition of the modified samples is confirmed by IR spectroscopy. The AS–TSC, AS–1-FTSC, and AS–4-FTSC modified aluminosilicates are characterized as adsorbents for the extraction of Ni(II) ions from aqueous solutions. The time of establishment of adsorption equilibrium is 60 min in the AS–TSC adsorbent–adsorbate system and 120 min for the AS–1-FTSC adsorbent–adsorbate, AS–4-FTSC adsorbent–adsorbate, and AS adsorbent–adsorbate systems. The maximum values of adsorption of Ni(II) ions are 1.71 mmol/g (100.8 mg/g), 0.25 mmol/g (15.0 mg/g), 0.37 mmol/g (21.9 mg/g), respectively, for the samples of AS–TSC, AS–1-FTSC, and AS–4-FTSC. The obtained data on adsorption are in the best possible way described by the Langmuir and Freundlich models. Presumably, the adsorption of heavy metal ions on the surface of the AS–TSC, AS–1-FTSC, and AS–4-FTSC modified zeolites is accompanied by the formation of chelate complexes (with the 1 : 1 composition) formed due to the donor–acceptor interaction of the metal ions with the nitrogen and sulfur atoms of the thiosemicarbazide fragment.