Yang Jae-Kyu, Lee Seung-Mok, Davis Allen P
School of Civil and Environmental Engineering, Kwandong University, Yangyang 215-802, Republic of Korea.
J Colloid Interface Sci. 2006 Mar 1;295(1):14-20. doi: 10.1016/j.jcis.2005.08.019. Epub 2005 Aug 30.
Cu(II)/EDTA adsorption onto TiO2 has been studied with a variation of pH, ionic strength, and type of background electrolytes. Cu(II) adsorption onto TiO2 increased as ionic strength increased when NaClO4 was used as a background electrolyte. This can be explained by the increase of exp(-FPsi/RT) as a part of the electrostatic correction within a surface complexation model. Model predictions described experimental adsorption trends. Types of background anions (ClO4, Cl, NO2, NO3, SO3, and PO4) did not affect adsorption trends and adsorption amounts of Cu(II) onto TiO2. However, different trends were observed with various types of background ions used as ionic strength in EDTA and Cu(II)-EDTA adsorption. EDTA adsorption was decreased by using Na2SO3 and Na3PO4 as background ions, while NaClO4, NaCl, NaNO2, and NaNO3 showed negligible interference on the EDTA adsorption, which matched well with model predictions. The presence Na2SO3 and Na3PO4 also interfered with Cu(II)-EDTA adsorption, to a somewhat greater extent compared to EDTA adsorption, especially at lower pH. This interference was also noted in Cu(II)-EDTA adsorption with a variation of Cu(II)-EDTA concentration at constant ionic strength (3 x 10(-3) M) by using Na2SO3 and Na3PO4, especially at lower ratios of Cu(II)-EDTA to Na2SO3 and Na3PO4. These results suggest that the ratio of Cu(II)-EDTA to Na2SO3 and Na3PO4 is an important factor for the controlling of competition between these background ions and Cu(II)-EDTA onto TiO2. Model prediction generally matched well with experimental adsorption using NaClO4, NaCl, NaNO2, and NaNO3 as backgrounds ions, while a severe deviation was observed in the presence of Na2SO3 and Na3PO4. These results suggest that the mobility of copper ions as Cu(II)-EDTA can be increased from polluted area in the presence of multivalent background ions, especially as the ratio of adsorbates/background ions decreased.
研究了在不同pH值、离子强度和背景电解质类型条件下，Cu(II)/EDTA在TiO₂上的吸附情况。当使用高氯酸钠（NaClO₄）作为背景电解质时，随着离子强度的增加，Cu(II)在TiO₂上的吸附量增加。这可以通过表面络合模型中作为静电校正一部分的exp(-FPsi/RT)的增加来解释。模型预测描述了实验吸附趋势。背景阴离子类型（ClO₄、Cl、NO₂、NO₃、SO₃和PO₄）不影响Cu(II)在TiO₂上的吸附趋势和吸附量。然而，在EDTA和Cu(II)-EDTA吸附中，使用不同类型的背景离子作为离子强度时，观察到了不同的趋势。使用亚硫酸钠（Na₂SO₃）和磷酸钠（Na₃PO₄）作为背景离子时，EDTA的吸附量降低，而高氯酸钠、氯化钠、亚硝酸钠和硝酸钠对EDTA吸附的干扰可忽略不计，这与模型预测结果吻合良好。Na₂SO₃和Na₃PO₄的存在也会干扰Cu(II)-EDTA的吸附，与EDTA吸附相比，干扰程度更大，尤其是在较低pH值时。在使用Na₂SO₃和Na₃PO₄、离子强度恒定（3×10⁻³ M）、改变Cu(II)-EDTA浓度的情况下，Cu(II)-EDTA吸附中也观察到了这种干扰，尤其是在Cu(II)-EDTA与Na₂SO₃和Na₃PO₄的比例较低时。这些结果表明，Cu(II)-EDTA与Na₂SO₃和Na₃PO₄的比例是控制这些背景离子与Cu(II)-EDTA在TiO₂上竞争的重要因素。使用高氯酸钠、氯化钠、亚硝酸钠和硝酸钠作为背景离子时，模型预测与实验吸附结果总体吻合良好，而在存在Na₂SO₃和Na₃PO₄时观察到严重偏差。这些结果表明，在多价背景离子存在的情况下，尤其是吸附质/背景离子比例降低时，作为Cu(II)-EDTA的铜离子的迁移率可能会从污染区域增加。
