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SUPPORTED LIX-84 LIQUID MEMBRANES FOR METAL ION SEPARATION: A STUDY ON METAL ION SORPTION EQUILIBRIUM AND KINETICS
Citation:
Cooper, C., M A. Gonzalez*, AND Lin, J. (Y.S.). SUPPORTED LIX-84 LIQUID MEMBRANES FOR METAL ION SEPARATION: A STUDY ON METAL ION SORPTION EQUILIBRIUM AND KINETICS. Presented at North American Membrane Society National Meeting, Lexington, KY, 5/15-20/2001.
Description:
Supported 2-hydroxy-5-nonyl-acetophenone oxime (LIX-84) liquid membranes have potential applications for the removal (or recovery) of copper ions from waste streams. But, the stability of such a liquid membrane remains the major hurdle for its practical applications. Inorganic supported LIX-84 membranes may offer an improved stability. Our research program will be focused on the preparation of supported LIX-84 membranes on hydrophilic, porous silica supports. The initial part of this progam is to examine whether the LIX-84 can be attached on the porous silica and to study the properties of metal ion sorption and stability of the silica supported LIX-84. The present paper will be focused on the results of this initial study. Several methods were attempted to attach LIX-84 to the silica particles, but the use of dichlorodimethyl silane (DCDMS) was the only method that worked well. It is believed that LIX-84 is bound to the surface by hydrophobic interactions between the methyl groups of DCDMS and the nine to twelve carbon chain of the LIX-84. The attachment of LIX-84 to the surface of the silica particles was seen to affect the adsorption properties of this chelating agent. The capacity of the functionalized silica for Ca2+, Cd2+, Cu2+, Pb2+, Zn2+, and Ni2+ uptake was examined in the range of 10-200 ppm. For pH values as high as 3.5 the functionalized silica behaved the same as LIX-84 in kerosene solvent and showed capacity only for Cu2+. At higher pH values the functiionalized silica also showed capacity for Ni2+ and Pb2+ but not Zn2+. Small increases in temperature greatly increased the adsorption rate for Cu2+. The LIX-84 exhibited excellent stability in 0.35 molar nitric and 0.1 molar hydrochloric acid solutions. 95% of the Cu2+ adsorbed was recovered using a 2% nitric acid aqueous solution. The adsorbent showed little loss in capacity with consecutive uses.