• Journal of the Mineralogical Society of Korea
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• v.16 no.4
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• pp.321-331
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• 2003

We researched the variation of mineral composition with depth and the Cu adsorption behavior of Hwangto in the Okjong area, Hadong. The 4 Hwangto samples were collected from depth 10 cm, 25 cm, 2∼3 m and under 3 m from surface, and analyzed using the X­ray Diffractometer. The Hwangto samples were mostly composed of clay minerals such as kaolinite and halloysite. Two samples from 10 cm and 25 cm contained Fe or Al hydroxide minerals, for example goethite or gibbsite. As depth increases, the content of quartz decreases but that of kaolinite increases. The amount of Cu removal was rapidly rised from pH 4, and reached about 90％ at pH 6 and above 90％ at pH 7. It is regarded that the trend of Cu removal was affected by the difference in mineral composition. It was relatively well matched between experimental value and calculated value by MINTEQA2 program in the case of high Cu concentration. From this study the precipitation has important role for the removal of Cu ions, particularly in the case of high Cu concentration. However, it was discord between experimental value and calculated one in the dilute concentration circumstances. The reason may be the mistake in parameters, insufficient reaction time, and inadequate consideration of reaction site in mineral surface.

• Journal of the Mineralogical Society of Korea
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• v.17 no.3
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• pp.209-220
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• 2004

Adsorption behavior of Cu onto Hwangto, from Pankok-ri, Kosung-gun, suspension was studied using Cu batch adsorftion experiment and computer program MINTEQA2 and FITEQL 3.2. The sorption of copper was investigated as a function of pH, copper concentration and $NaNO_3$ background concentration (0.01 and 0.1 M). The concentration of copper was analyzed using ICP-AES. The sorption of copper onto Hwangto suspension increased with increasing pH and copper concentration. The adsorption percentage of copper drastically increased from pH 5.5 to 6.5, and reached nearly 100% at pH 7.5. Because the amount of copper solution and the ionic strength of background electrolyte may not affect the sorption of copper onto Hwangto, the copper ion may be combined at the surface of Hwangto as an inner-sphere complex. Using the MINTEQA2 program, the speciation of copper was calculated as a function of pH and copper concentration. The concentration of $Cu^{2+}$ decreased and that of $Cu(OH)_2$ increased with increasing pH. The uptake of copper in the Hwangto suspension was simulated by FITEQL3.2 program using two sites-three pKas model, which is composed of silicate reaction site and Fe oxide reaction site. The copper absorption reaction constants were calculated in the case of 2～6 mL of copper solution. The Fe oxide reaction site rapidly adsorbs copper ion between pH 4.5～6.5. Silicate reaction site adsorbs little copper ion at low copper concentration but much at high copper concentration. The removal amount of copper by precipitation was negligible in comparison with that of adsorption. The Fe oxide reaction site may has higher adsorption affinity of copper ion than silicate reaction site.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.3
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• pp.345-351
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• 2008

Fe-impregnated activated carbon(Fe-AC) was prepared by Fe(III) loading on activated carbon(AC) in various preparation pH. In order to evaluate the stability of Fe-AC, dissolution of iron from Fe-AC in acidic conditions was measured. In addition, batch experiments were conducted to monitor the removal efficiency of copper by Fe-AC. Results of stability test for Fe-AC showed that the amount of extracted iron increased with contact time but decreased with increasing solution pH. The dissolved amount of iron gradually increased at solution pH 2 and finally 13% of the total iron loaded on activated carbon was extracted after 12 hr. However dissolution of iron was negligible over solution pH 3. Removal of Cu(II) by Fe-AC was greatly affected by solution pH and was decreased as solution pH increased as well as initial Cu(II) concentration decreased. Surface complexation modeling was performed by considering inner-sphere complexation reaction and using the diffuse layer model with MINTEQA2 program.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.7
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• pp.712-720
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• 2008

Sediment and interstitial water samples from ten lagoons in the Northeastern coastal part of South Korea were analyzed to obtain the concentrations of metals and inorganic ligand. These data, coupled with pH and ionic strength, were used to compute the aqueous speciation of the metals in the interstitial water using the MINTEQA2 equilibrium program. The K and Na were almost entirely present as the free aqua ions, but Co, Cd, Ni, Pb and Zn were existed as various metal-ligand complexes. Metals such as Al, As, and Cr formed 3$\sim$4 metal-ligand complexes. In the interstitial water with high chloride concentrations, almost all of the metals were dominated by free aqua ions. Metals of Cd, Co, Ni, Pb and Zn were bound as chloride-metal complexes of the type M$^{x+}$ + xCl$^-$, and Fe, Mn and Mg were dominated by sulfate equilibria(M$^{2+}$ + SO$_4{^{2-}}$). Hg(II) was speciated as HgCl$_2$(aq), HgCl$_3{^-}$ and HgCl$_4{^-}$. However, in the interstitial water with low chloride concentrations, Hg(II) and Cd(II) were existed as chloride-metal complexes, metals of Cu, Mg, Mn, Ni, Pb and Zn were dominated by sulfate equilibria, and the speciation of Fe(II) was bound as Fe(OH)$_2{^+}$, Fe(OH)$_3$(aq). However, Al, As and Cr were dominated by hydroxy-metal and oxide-metal species in nearly all of the lagoons.