The H+/Zn2+ Exchange Stoichiometry of Surface Complex Formation on Synthetic Amorphous Aluminosilicate

✍ Scribed by Akane Miyazaki; Makoto Tsurumi

• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 195 KB
• Volume: 172
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.1995.1260

✦ Synopsis

Surface complex formation between synthetic amorphous aluminosilicate and (\mathrm{Zn}^{2+}) ion in (0.1 \mathrm{~N} \mathrm{NaNO}{3}) was studied at 25 (\pm 0.1^{\circ} \mathrm{C}) by potentiometry. The concentration of (\mathrm{Zn}^{2+}) in the suspension was varied, while the concentration of the aluminosilicate was kept constant at (1 \mathrm{~g}) air-dried aluminosilicate in 11. The (\mathrm{pH}) value of the suspension was kept constant at 6.50 by (0.01 \mathrm{~N} \mathrm{NaOH}) with an automatic titration system to neutralize (\mathrm{H}^{+})released from the solid phase. The amount of (\mathrm{Zn}) (II) retained on the solid phase was calculated from the difference between the total (\mathrm{Zn}^{2+}) concentration in the suspension and the equilibrated concentration of (\mathrm{Zn}^{2+}) in the liquid phase. The molar ratio of (\mathrm{Zn}) (II) retained on the solid surface to (\mathrm{H}^{+})released from the solid phase is (1: 2), suggesting ion exchange of two surface (\mathrm{H}^{+})and one aqueous (\mathrm{Zn}^{2+}) ion with conservation of charge balance. The surface complex formation between synthetic amorphous aluminosilicate and (\mathrm{Zn}^{2+}) ion in aqueous solution can be described as (2{\mathrm{Al}, \mathrm{Si}-\mathrm{OH}}+\mathrm{Zn}^{2+}(\mathrm{aq})=\left{(\mathrm{Al}, \mathrm{Si}-\mathrm{O}){2} \mathrm{Zn}\right}+) (2 \mathrm{H}^{+}(\mathrm{aq})), where {} represents the chemical species on the solid surface. 1995 Academic Press, Inc.