Adsorption Characteristics of Fumarate, Maleate, and Succinate on Hydrous δ-Al2O3

• Main Authors: Yao, Hsi-Liang, 姚希亮
• Other Authors: Hsuan-Hsien Yeh
• Format: Others
• Language: zh-TW
• Published: 1996
• Online Access: http://ndltd.ncl.edu.tw/handle/47700641104393174441

博士 === 國立成功大學 === 環境工程學系 === 84 === ABSTRACT　　Adsorption behaviors among fumarate, maleate and succinate were compared using the same adsorbent δ-Al2O3 and initial adsorbate concentrations. Firstly, the adsorption maxima were found all near the midpoint of their respective two pK values indicating that the adsorption of HX- was more favorable than H2X and X2-, and the adsorption densities were significantly influenced by the electrostatic microenvironment. The adsorption maxima of maleate were about 10 % higher than those of fumarate but close to or slightly less than those of succinate before saturation was approached. However, when the adsorbent surface became crowded, the saturated adsorption maxima of maleate and succinate were about 1/3 and 1/2, respectively, higher than that of fumarate, indicating that the trans-form isomer occupied more binding space than the cis-form, and the single bond anion (succinate) occupied the least binding space among the three four-carbon dicarboxylic acids(FCDAs) due to its molecular flexibility.　　Secondly, although these FCDAs can be adsorbed specifically on hydrous δ-Al2O3, the isoelectric point (IEP) was not observed to shift in the three adsorption systems studied due to insignificant adsorption near the IEP and low intrinsic binding affinity of these acids for the oxide surface. Evidence of low intrinsic affinity arose from the strong ionic-strength dependence of the adsorption behavior for each of the three FCDAs. The ionic-strength effects on the adsorption behavior found for maleate were close to or slightly stronger than those of succinate, while fumarate exhibited the strongest ionic-strength dependence among the three FCDAs. These results were well related to their respective adsorption maxima (under-saturation) stated above. Therefore, it is suggested that, under the same experimental conditions, the adsorption of a particular anion will be attributed to specific adsorption if the ionic-strength effects of this anion are weaker than any of the three FCDAs studied. In addition, the lack of a shift in the isoelectric point can not be used for judging whether the adsorption is non-specific.