Separation science and purification technologies are well known in the art and have received increased attention in recent years because of environmental concerns and need for environmental clean-up. A technique in this art is solid phase extraction (SPE), which has received considerable attention recently. SPE is widely used for pre-concentration and cleanup of analytical samples, for purification of various chemicals, and for large scale applications such as removal of toxic or valuable substances from many, predominantly aqueous solutions as is disclosed in U.S. Pat. No. 5,071,565. Others such as Rostad et al., "Bonded-Phase Extraction Column Isolation of Organic Compounds in Groundwater at a Hazardous Waste Site", Anal. Chem. 1984, 56, 2856-2860, have utilized particle packed columns for SPE. SPE-utilizing particle loaded membranes has been taught by Hagen et al., "Membrane Approach to Solid Phase Extraction," Anal. Chim. Acta 1990, 236, 157-164 and Markell et al., "New Technologies in Solid Phase Extraction," LC/GC 1991, 9, Number 5, U.S. Pat. Nos. 4,810,381, 4,906,378, 4,971,736, 5,071,610, 5,147,539, 5,207,915, and 5,279,742.
Use of molecular sieves in separation science is also well known and has been described in the chemical literature. For example, "Lead Removal from Waste Waters Using Chabazite Tuff" was reported by C. Colella and M. Pansini in "Perspectives in Molecular Sieve Science"; Flank, W. H., and Whyte Jr., T. E., Ed.; ACS Symposium Series 368; American Chemical Society: Washington, D.C., 1988, chapter 32. K. Otto et al. used a zeolite in "Adsorption of Hydrocarbons and Other Exhaust Components on Silicalite" in Ind. Eng. Chem. Res. 1991 30, 2333-2340, and C. D. Chriswell et al. described "Use of Silicalite Molecular Sieve for Gas Chromatographic Determination of Permanent Gases and Volatile Hydrocarbons Emitted During Coal Processing" in the J. Chromatogr. 1987, 405, 213-220. C. D. Chriswell and D. T. Gjerde sampled stack gas for sulfur dioxide with a molecular sieve adsorbent as reported in Anal. Chem. 1982, 54, 1911-1913. G. M. W. Schultz-Sibbel et al. in "Analytical Investigation of the Properties and Uses of a New Hydrophobic Molecular Sieve" (Talanta, 1982, 29, 447-452) characterized distribution coefficients and capacities of silicalite. Unlike aluminosilicate zeolites, which are hydrophilic, silicalite is hydrophobic/organophilic and selectively adsorbs organic molecules over water as reported by E. M. Flanigen et al., "Silicalite, a New Hydrophobic Crystalline Silica Molecular Sieve" in Nature 1978, 271, 512-516.
Use of molecular sieves in separation science has also been described in the patent literature. For example, U.S. Pat. No. 5,100,596 provides a method for synthesis of a membrane comprised purely of a molecular sieve useful in the separation of gaseous or liquid mixtures. The patent further states (col. 1, lines 26-28) that "The potential of zeolites as components in microporous membranes has not been fully explored." U.S. Pat. No. 5,013,335 teaches a process for sequestering ammonia and the odor associated therewith using a crystalline siliceous molecular sieve. U.S. Pat. No. 4,826,497 describes fibrous absorbent articles such as diapers and bandages and the like which contain molecular sieves for deodorizing. U.S. Pat. Nos. 4,855,154 claims a process for deodorizing marine oils using molecular sieves and 4,648,977 provides a process for removing toxic organic materials from aqueous solutions in contact with organophilic molecular sieves. European Patent Application 88301879.8 teaches a process for the recovery of halogenated hydrocarbons in a gas stream. The stream is passed through a bed of hydrophobic molecular sieves which sorbs the hydrocarbons.
Membranes comprising sorptive media in a polytetrafluoroethylene (PTFE) fibril matrix useful in separation science has been described in U.S. Pat. No. 5,071,610. A method for isolating organic materials using SPE comprises a polytetrafluoroethylene (PTFE) fibril matrix in which are enmeshed sorptive particles and a novel article and also stacked article for use as an extraction medium is disclosed in U.S. Pat. Nos. 5,279,742. 5,328,758 discloses particle loaded melt blown microfiber (BMF) composites for SPE.
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