Preparation of organically functionalized silica gel as adsorbent for copper ion adsorption

The pectin/functionalized silica coated filter paper (FILPSL2) was used for copper ion adsorption. Silica sol (1), prepared by mixing ethanol, water, TEOS and hydrochloric acid, was slowly added into pectin solution. A piece of filter paper (2 cm x 2 cm) was immersed in the silica-pectin solution for 1 hr. The coated filter paper was dried at room temperature and then oven-dried at 50 °C for 6 hrs to obtain FILPS. The silica sol (2) was subsequently prepared by mixing ethanol, water, N-[3-(Trimethoxysilyl) propyl] ethylenediamine (L2) and hydrochloric acid. The FILPS was immersed in silica sol (2) and the coated paper was oven-dried at 50 °C for 6 hrs to obtain FILPSL2. The SEM micrograph of uncoated Filter paper (FIL) and FILPSL2 showsa characteristic woven pattern. For copper ion adsorption, FILPSL2 was put into 0.1 M of CuCl2solution (pH 2, 25 °C). The color of the paper changes from off-white to intense blue within 5 min due to the complex between amino group of functionalized silica and Cu2+ as evidenced from IR spectroscopy.The equilibrium adsorption percentage and adsorption capacity were 27.10 and 5.5 x 10-3 respectively. The concentrations of copper ion solutions were varied to 10-2and 10-3M at this pH. The lower concentration of copper ion results in the higher adsorption percentage. While the lower concentration of copper ion results in the lower adsorption capacity. The adsorption was also experimented at pH 3.The similar trend was obtained. The optimum pH for adsorption for all concentrations was 2. The effect of interferences on the copper ion adsorption depends on the pH. At pH 2, Ni2+ has a stronger effect. While Cd2+ has a stronger effect at pH 3. The desorption was performed using 0.2 M CH3COOH solution. The complete desorption occurred within 30 min.

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Amine-Functionalized Silica Monolith as a Copper Ion Adsorbent

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1131.198 ◽

2015 ◽

Vol 1131 ◽

pp. 198-202

Author(s):

Radchada Buntem ◽

Kewarin Pramual

Keyword(s):

Metal Ion ◽

Copper Ion ◽

Tetraethyl Orthosilicate ◽

Ion Concentration ◽

Polymerization Process ◽

Ion Adsorption ◽

Functionalized Silica ◽

Silica Monoliths ◽

Silica Monolith ◽

Amine Functionalized

Amine-functionalized silica monoliths were prepared by co-condensation between tetraethyl orthosilicate and N-[3-(trimethoxysilyl) propyl] ethylenediamine.The mixture between ethanol, H2O, tetraethyl orthosilicate, N-[3-(trimethoxysilyl) propyl] ethylenediamine and 1M HCl was stirred for 1 hour at room temperature to obtain a clear silica sol. 1.2 g of the sol was poured into plastic vial with the paraffin cover and left for 2 days for the polymerization process to obtain the gel. The disc-shape gel was dried in the oven at 50 °C for 10 hours. The silica monolith obtained was weighed and analyzed by IR spectroscopy and BET method. The disc-shape silica monoliths were further used for copper ion adsorption studies. The factors affecting the copper ion adsorption like pH, copper ion concentration and metal ion interference were studied. The pHs of CuCl2 aqueous solutions were varied from pH 2 to pH 6. While the Cu2+ concentrations under this study were 10-1, 10-2, 10-3, 10-4, 10-5 and 10-6 M. The cationic interferences used were Cd2+ and Ni2+. For the copper ion concentration, the higher the concentration results in the higher adsorption capacity. At the lower concentrations like 10-4, 10-5 and 10-6 M, a complete adsorption was obtained. The color of the Cu2+ - loaded monolith was changed to blue due to the complex between amino groups on the silica and the Cu2+ as evidenced by IR analysis. The monolith after adsorption was also analyzed by SEM/EDS. The inferences like Cd2+ and Ni2+ affect the Cu2+ adsorption at different degree. The desorption could be successfully performed by using 0.1 M HCl solution.

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