Physicochemical characteristics for adsorption of MTBE and cadmium on clay minerals |
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Authors: | Joo-Hyun Sim Hyung-Joon Seo Chang-Gyun Kim |
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Institution: | (1) Department of Environmental Engineering, Inha University, 253 Yonghyundong Namgu, Incheon, Korea; |
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Abstract: | Physicochemical characteristics relevant to the adsorption of MTBE and Cd on three types of clay minerals were investigated.
The characteristics were examined through batch adsorption tests conducted under various experimental conditions such as adsorption
time, ratio of solution-to soil, concentration of solutes, concentration of organic matters, pH, and zeta potential. The adsorption
efficiency of MTBE or Cd on three types of clays decreased in response to an increase of the ratio of solution-to-soil; nevertheless,
the adsorbed amounts inversely increased. MTBE was adsorbed on clays in an increasing order of vermiculite, bentonite, and
CTAB-bentonite. However, Cd was adsorbed in a different order of bentonite, vermiculite, and CTAB-bentonite. The adsorption
of MTBE was well fitted with the Freundlich model, whereas the Cd was more closely suited to a Langmuir equation. By adding
humic acids of 1 and 5%, MTBE was significantly adsorbed on bentonite and vermiculite, respectively, but beyond that, its
adsorption was diminished. In comparison, the adsorption on CTAB-bentonite was increased in proportion to the humic acids
addition. Likewise, the addition of humic acids acted to increase the adsorption of Cd regardless of the types of adsorbent,
where up to 90% of Cd was removed at pH 10. Further increase of pH declined the degree of zeta potential, while increasing
Cd concentration also lowered the zeta potential, which consequently contributes in enhancing the adsorption efficiency of
Cd on clays. |
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