Chemical modification of silica gel with hydrazine carbothioamide derivative for sorption studies of Cu(II), Ni(II) and Co(II) ions

2-((1H-pyrrol-2-yl)methylene)hydrazinecarbothioamide was chemically immobilized onto silica gel modified with 3-chloropropyltrimethoxy silane. The modified surfaces were characterized by infrared spectroscopy and thermogravimetric analysis. The sorption of Cu(II), Co(II), and Ni(II) ions were evaluated by using batch methods. The values of adsorption of metal ions were detected by an atomic absorption spectrometer. The influences of concentration, temperature, amount of metal ions, and pH to sorption on the modified silica gel with Schiff base were also investigated. The maximum adsorption capacities and isotherm parameters were calculated from the Langmuir, Freundlich, and Dubinin–Radushkevich (D–R) isotherm equations. Thermodynamic parameters such as free energy (∆G°), entropy (∆S°), and enthalpy (∆H°) were also calculated from the sorption results. The modified structure used as adsorbent was successfully employed in the removal of Cu(II), Ni(II), and Co(II) traces from the aqueous solutions.