層狀雙氫氧化物在不同pH值下對鉻酸鹽的吸附
Other Title
Sorption of Chromate by Layered Double Hydroxide at Different pH
Journal
土壤與環境
Journal Volume
8
Journal Issue
1
Start Page
35
End Page
45
ISSN
1029-2950
Date Issued
2005
Author(s)
Abstract
Chromate (Cr(VI)) has high mobility in the environment because the natural environmental particles ( such as clays or oxides) have low affinity with Cr(VI). For the purpose to decrease the threat of Cr(VI) in the environment, a complement, i.e., an anion adsorbent, needs to be developed. This study was to evaluate the adsorption of Cr(VI) by the synthesized layered double hydroxide (LDH). The potential of LDH to the fixation of Cr(VI) results from its high specific surface area and anionic exchange capacity. The results of this study showed that the sorption of chromate by LDH is largely influenced by pH. When chromium concentration is low (＜ 4.33 mM), adsorptive ability of LDH increases with increasing pH; on the contrary, an inverse trend on the pH dependence of Cr adsorption was shown at higher chromium concentration (＞ 4.33 mM), Using X-ray diffraction, the influence of temperature on the stability of LDH structure was determined. At room temperature, the reflections of gibbsite were detected when Cr(VI) adsorption proceeded. The result indicated that Li was de-intercalated from LDH, which subsequently resulted in the decrease of the Cr(VI) adsorption capacity of LDH. A decrease in the Cr(VI) adsorption was also observed in the corresponding kinetic experiment. These results demonstrated the possibility to control the Cr(VI) adsorption and desorption of LDH by changing the temperature of the system. This phenomenon may be subsequently utilized to develop a new technique for Cr(VI) treatment in which the adsorption capability of adsorbent can be switch on and off through changing the temperature of the treatment system.
Subjects
層狀雙氫氧化合物
鉻酸鹽
吸附
陰離子交換
layered double hydroxide (LDH)
chromate
adsorption
anion exchange
Type
journal article