R Holmes-Farley
Member
- Joined
- Jun 7, 2006
- Messages
- 9
In terms of chemistry of inorganic copper absorption, bare glass is likely to carry a net negative charge in seawater (from silicate) and can bind copper as a copper silicate complex. This is well established in the scientific literature:
Adsorption of some divalent cations from aqueous solution on precipitated silica. Bye, Gerald C.; McEvoy, Michael; Malati, Mounir A. Mid-Kent Coll. Higher Further Educ., Chatham, UK. Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases (1983), 79(10), 2311-18.
Abstract
The adsorption of Co2+, Ni2+, Cu2+, Zn2+, and Cd2+ on the K+ form of a pptd. silica is reported. The adsorption isotherms of Co2+ and of Ni2+ at pH 7.0 and different temps. follow the Langmuir isotherm. The endothermic apparent heats of adsorption, 2 and 10 kJ/mol, resp., are compared with those of Cu2+ and Cd2+. The limiting amt. adsorbed, Xm, of the 4 ions decrease as the pH is lowered. An ion-exchange mechanism between hydrated K+ ions in the outer Helmholtz layer and metal, M2+, ions in soln. is proposed. The results also suggest that (MOH)+ ions are adsorbed at the higher pH values. A plot of Xm at pH 6.0 and 323 K for the 5 ions studied against at. no. exhibits the Irving-Williams sequence. At pH 3.0, i.e. close to the point of zero charge of SiO2, the adsorption results were used to calc. the free energy of specific adsorption, DG, using the Grahame equation. The DG values were -11.1, -10.7, -13.4, -13.3, and -12.1 kJ/mol for Co, Ni, Cu, Zn, and Cd, resp. Specific adsorption is tentatively ascribed to the formation of surface coordination complexes.
Ion-exchange adsorption of zinc and copper ions on silica. Kozawa, A. Univ. Nagoya, Japan. Journal of Inorganic and Nuclear Chemistry (1961), 21(3/4), 315-24.
Abstract
Ion-exchange adsorption of Zn and Cu ions on silica were examd. in 2M NH4Cl contg. ZnO or ZnCl2 and in M NH4OAc contg. 0.05M CuCl2, resp. The ion-exchange adsorption attains equil. in about 2 hrs. at 25°. The adsorption of Zn++ increases with the pH of the soln. up to pH 7.12, then decreases. Between pH 5.48 and 6.38 the mole-ratio of H+ released Zn2+ adsorbed is const. at .apprx.3.0. Zn++ adsorption on heated silica decreases markedly with increase in the heating temp. For Cu++ adsorption, the mole-ratio, H+ rel./Cu2+ ads., is 4.0. The infrared absorption spectra of silica samples, heated silica, and silica treated with Zn2+, Cu2+, and Na+ solns., were taken. A decrease in the absorption intensities for the bending vibration of OH groups on the silica is discussed. A surface complex mechanism for metal ion adsorption of silica is proposed; the silica surface is acting as tridentate ligands for the Zn++ adsorption. A new method for detg. the surface acid and the surface area of silica is suggested.
Reaction of silica gel with copper ions in acetate solutions. II. Rak, R. V.; Dushina, A. P.; Aleskovskii, V. B. Leningr. Tekhnol. Inst. im. Lensoveta, Leningrad, USSR. Zhurnal Prikladnoi Khimii (Sankt-Peterburg, Russian Federation) (1971), 44(5), 1068-73.
Abstract
Sorption of Cu ions by silica gel from acetate solns. was studied under 2 different conditions: (a) contact time from 1 min to 24 hr using 4.7 ´ 10-2M Cu(NO3)2 in M AcONa; and (b) contact time from 2 to 120 days with 4.25 ´ 10-4-4.8 ´ 10-2M Cu(NO3)2 in M AcONa. The soly. of the polysilicate salts and the hydrated Cu silicates, in the form of activity products, Kp = aCu2+aSiO32- and Kc = aCu2+aSSiO32-, was (0.8 ± 0.1) ´ 10-19 and 1.9 ´ 10-19, resp.
Adsorption of some divalent cations from aqueous solution on precipitated silica. Bye, Gerald C.; McEvoy, Michael; Malati, Mounir A. Mid-Kent Coll. Higher Further Educ., Chatham, UK. Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases (1983), 79(10), 2311-18.
Abstract
The adsorption of Co2+, Ni2+, Cu2+, Zn2+, and Cd2+ on the K+ form of a pptd. silica is reported. The adsorption isotherms of Co2+ and of Ni2+ at pH 7.0 and different temps. follow the Langmuir isotherm. The endothermic apparent heats of adsorption, 2 and 10 kJ/mol, resp., are compared with those of Cu2+ and Cd2+. The limiting amt. adsorbed, Xm, of the 4 ions decrease as the pH is lowered. An ion-exchange mechanism between hydrated K+ ions in the outer Helmholtz layer and metal, M2+, ions in soln. is proposed. The results also suggest that (MOH)+ ions are adsorbed at the higher pH values. A plot of Xm at pH 6.0 and 323 K for the 5 ions studied against at. no. exhibits the Irving-Williams sequence. At pH 3.0, i.e. close to the point of zero charge of SiO2, the adsorption results were used to calc. the free energy of specific adsorption, DG, using the Grahame equation. The DG values were -11.1, -10.7, -13.4, -13.3, and -12.1 kJ/mol for Co, Ni, Cu, Zn, and Cd, resp. Specific adsorption is tentatively ascribed to the formation of surface coordination complexes.
Ion-exchange adsorption of zinc and copper ions on silica. Kozawa, A. Univ. Nagoya, Japan. Journal of Inorganic and Nuclear Chemistry (1961), 21(3/4), 315-24.
Abstract
Ion-exchange adsorption of Zn and Cu ions on silica were examd. in 2M NH4Cl contg. ZnO or ZnCl2 and in M NH4OAc contg. 0.05M CuCl2, resp. The ion-exchange adsorption attains equil. in about 2 hrs. at 25°. The adsorption of Zn++ increases with the pH of the soln. up to pH 7.12, then decreases. Between pH 5.48 and 6.38 the mole-ratio of H+ released Zn2+ adsorbed is const. at .apprx.3.0. Zn++ adsorption on heated silica decreases markedly with increase in the heating temp. For Cu++ adsorption, the mole-ratio, H+ rel./Cu2+ ads., is 4.0. The infrared absorption spectra of silica samples, heated silica, and silica treated with Zn2+, Cu2+, and Na+ solns., were taken. A decrease in the absorption intensities for the bending vibration of OH groups on the silica is discussed. A surface complex mechanism for metal ion adsorption of silica is proposed; the silica surface is acting as tridentate ligands for the Zn++ adsorption. A new method for detg. the surface acid and the surface area of silica is suggested.
Reaction of silica gel with copper ions in acetate solutions. II. Rak, R. V.; Dushina, A. P.; Aleskovskii, V. B. Leningr. Tekhnol. Inst. im. Lensoveta, Leningrad, USSR. Zhurnal Prikladnoi Khimii (Sankt-Peterburg, Russian Federation) (1971), 44(5), 1068-73.
Abstract
Sorption of Cu ions by silica gel from acetate solns. was studied under 2 different conditions: (a) contact time from 1 min to 24 hr using 4.7 ´ 10-2M Cu(NO3)2 in M AcONa; and (b) contact time from 2 to 120 days with 4.25 ´ 10-4-4.8 ´ 10-2M Cu(NO3)2 in M AcONa. The soly. of the polysilicate salts and the hydrated Cu silicates, in the form of activity products, Kp = aCu2+aSiO32- and Kc = aCu2+aSSiO32-, was (0.8 ± 0.1) ´ 10-19 and 1.9 ´ 10-19, resp.