Skip to Content
Merck
  • The removal and recovery of Cr(VI) by Li/Al layered double hydroxide (LDH).

The removal and recovery of Cr(VI) by Li/Al layered double hydroxide (LDH).

Journal of hazardous materials (2006-09-19)
L C Hsu, S L Wang, Y M Tzou, C F Lin, J H Chen
ABSTRACT

Hexavalent Cr has been identified as one of the toxic metals commonly present in industrial effluents. Among the treatment techniques developed for removing Cr(VI) from waste waters, sorption is most commonly applied, due to its simplicity and efficiency. However, few adsorbents can be recycled and reused cost-effectively. In this study, the removal and recovery of Cr(VI) from water using Li/Al LDH was investigated. The removal of Cr(VI) by Li/Al LDH was evaluated in a batch mode. The results demonstrated that Cr(VI) adsorption onto Li/Al LDH occurs by replacing the Cl(-) that originally exists in the interlayer of the adsorbent. The degree of Cr(VI) adsorption observed for Li/Al LDH was relatively high and the process occurred rapidly; however, a portion of adsorbed Cr(VI) was gradually desorbed, due to the Li de-intercalation of Li/Al LDH. Lithium de-intercalation from Li/Al LDH with interlayer Cl(-) and interlayer Cr(VI) follows the first order kinetics and has the activation energies of 76.6 and 41.5 kJ mol(-1), respectively. The properties of thermal unstability and the high adsorption capacity of Li/Al LDH may lead to the development of an innovative technique for the removal of Cr(VI) from Cr(VI)-containing wastewater. That is, Li/Al LDH may be used as an effective adsorbent for the adsorption of Cr(VI) in an ambient environment. Following the adsorptive process, the adsorbed Cr(VI) may be released, using heated water to treat the Cr(VI)-containing Li/Al LDH particles. Through this hydrothermal treatment of the used adsorbent, Cr(VI) can be recovered and the solid product (gibbsite) can be recycled for further use.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Lithium hydroxide monohydrate, 99.95% trace metals basis
Sigma-Aldrich
Lithium hydroxide monohydrate, BioUltra, ≥99.0% (T)
Sigma-Aldrich
Lithium hydroxide monohydrate, BioXtra, 98.5-101.5% (titration)
Sigma-Aldrich
Lithium hydroxide monohydrate, ACS reagent, ≥98.0%
Sigma-Aldrich
Lithium hydroxide, powder, reagent grade, ≥98%
Sigma-Aldrich
Lithium hydroxide, reagent grade, 98%