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Title: Supported polymeric liquid membranes for wastewater treatment

Abstract

The removal or elimination of organic residues from aqueous waste streams represents a major need in the chemical industry. A class of membrane has been developed called supported polymeric liquid membranes capable of removing and concentrating low molecular weight organic compounds from dilute aqueous solutions, especially those that also contain high concentrations of inorganic salts. These membranes are prepared by filling the pores of microfiltration or ultrafiltration membranes with polymeric (oligomeric) liquids having affinity for the organic compounds of interest. With this approach, membrane`s separation characteristics are decoupled from its mechanical stability and depend primarily on the chemical properties of the liquid polymer used. As a result, membranes of diverse separation capabilities can be conveniently prepared using liquid polymers possessing the appropriate functional groups. Physical properties typical of polymeric liquids such as high viscosity, extremely low volatility and insolubility in water contribute to the observed stability of the membranes under broad operating conditions. This membrane process has been successfully applied to several aqueous waste streams. This paper describes the early development activities for treating a waste stream containing a dilute mixture of C2-C6 carboxylic acids. Feasibility testings were initially carried out with flat sheet membranes in a small stirred cell.more » Scaleup was then conducted using hollow fiber membranes, first with small modules prepared in the laboratory, then with a much larger commercial module. Attractive features of this membrane process include the ability to recover the contaminants in concentrated form for either recycle or more economical disposal, low pressure (ambient) operation, simple scale-up using commercial hollow fiber modules, and ease of in-situ regeneration of the polymeric liquid.« less

Authors:
 [1]
  1. Monsanto Co., St. Louis, MO (United States)
Publication Date:
OSTI Identifier:
353607
Report Number(s):
CONF-970677-
TRN: IM9929%%153
Resource Type:
Conference
Resource Relation:
Conference: 90. annual meeting and exhibition of the Air and Waste Management Association, Toronto (Canada), 8-13 Jun 1997; Other Information: PBD: 1997; Related Information: Is Part Of 1997 proceedings of the Air and Waste Management Association`s 90. annual meeting and exhibition; PB: [7000] p.
Country of Publication:
United States
Language:
English
Subject:
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; INDUSTRIAL WASTES; CHEMICAL INDUSTRY; WASTE PROCESSING; WASTE WATER; SUPPORTED LIQUID MEMBRANES; PERFORMANCE TESTING; CARBOXYLIC ACIDS

Citation Formats

Ho, S.V.. Supported polymeric liquid membranes for wastewater treatment. United States: N. p., 1997. Web.
Ho, S.V.. Supported polymeric liquid membranes for wastewater treatment. United States.
Ho, S.V.. 1997. "Supported polymeric liquid membranes for wastewater treatment". United States. doi:.
@article{osti_353607,
title = {Supported polymeric liquid membranes for wastewater treatment},
author = {Ho, S.V.},
abstractNote = {The removal or elimination of organic residues from aqueous waste streams represents a major need in the chemical industry. A class of membrane has been developed called supported polymeric liquid membranes capable of removing and concentrating low molecular weight organic compounds from dilute aqueous solutions, especially those that also contain high concentrations of inorganic salts. These membranes are prepared by filling the pores of microfiltration or ultrafiltration membranes with polymeric (oligomeric) liquids having affinity for the organic compounds of interest. With this approach, membrane`s separation characteristics are decoupled from its mechanical stability and depend primarily on the chemical properties of the liquid polymer used. As a result, membranes of diverse separation capabilities can be conveniently prepared using liquid polymers possessing the appropriate functional groups. Physical properties typical of polymeric liquids such as high viscosity, extremely low volatility and insolubility in water contribute to the observed stability of the membranes under broad operating conditions. This membrane process has been successfully applied to several aqueous waste streams. This paper describes the early development activities for treating a waste stream containing a dilute mixture of C2-C6 carboxylic acids. Feasibility testings were initially carried out with flat sheet membranes in a small stirred cell. Scaleup was then conducted using hollow fiber membranes, first with small modules prepared in the laboratory, then with a much larger commercial module. Attractive features of this membrane process include the ability to recover the contaminants in concentrated form for either recycle or more economical disposal, low pressure (ambient) operation, simple scale-up using commercial hollow fiber modules, and ease of in-situ regeneration of the polymeric liquid.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 1997,
month =
}

Conference:
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  • A novel membrane was developed by growing polymer chains from the surface of a porous ceramic support, resulting in a composite membrane which combines the mechanical properties of the inorganic membrane with the selective interactions of the polymer. The configuration of the grafted polymer brush layer is determined by solvent-polymer interactions, with a hydrophilic polymer being stretched away from the surface by aqueous solutions and collapsed against the surface by organic solvents. This behavior of the grafted chains provides Ceramic-Supported Polymeric (CSP) membranes with unique properties for certain water treatment applications. One application envisioned for these CSP membranes, in whichmore » the selectivity is influenced by interactions between the solvent and the grafted polymer, is the cross-flow filtration of an oil-in-water emulsion. In this case, a hydrophilic grafted Polyvinylpyrrolidone (PVP) brush layer expanded into the pore volume due to the affinity of the polymer for water. These extended grafted chains preferentially allow the passage of water over oil, producing a permeate stream with a lower total organic carbon content compared to an unmodified membrane. Another advantage of the CSP membrane is in reducing permeate flux decline believed to be caused by the adsorption of oil onto the membrane surface. For the PVP-modified CSP membrane, the grafted polymer alters the membrane surface character from hydrophobic to hydrophilic, reducing the tendency for oil adsorption. This phenomenon was demonstrated by comparison of permeate flow rate behavior for both unmodified and graft polymerized (CSP) membranes.« less
  • Recent experience in practical application of Supported Liquid Membranes (SLM or SUPLIM) both in the hydrometallurgy and nuclear technology has been analyzed. The results obtained allow one to consider SUPLIM as a promising technology for radioactive waste treatment. This statement is based on the evaluation of integrated socioeconomic effects, including quantity of additional chemicals, the volume of secondary technological streams and secondary wastes, simplicity and the low costs of equipment used, potential possibility to organize in situ process, and the level of the harmful impact on personnel. 35 refs.
  • As compared to other gas separation techniques, membranes have several advantages which can include low capital cost, relatively low energy usage and scalability. While it could be possible to synthesize the ideal polymer for membrane separation of carbon dioxide from fuel gas, it would be very intensive in terms of money and time. Supported liquid membranes allow the researcher to utilize the wealth of knowledge available on liquid properties. Ionic liquids, which can be useful in capturing CO2 from fuel gas because they posses high CO2 solubility in the ionic liquid relative to H2, are an excellent candidate for thismore » type of membrane. Ionic liquids are not susceptible to evaporation due to their negligible vapor pressure and thus eliminate the main problem typically seen with supported liquid membranes. A study has been conducted evaluating the use of the ionic liquid 1-hexyl-3-methyl-imidazolium bis(trifuoromethylsulfonyl)imide in supported ionic liquid membranes for the capture of CO2 from streams containing H2. In a joint project, the ionic liquid was synthesized and characterized at the University of Notre Dame, incorporated into a polymeric matrix, and tested at the National Energy Technology Laboratory. Initial results have been very promising with calculated CO2 permeabilities as high as 950 barrers and significant improvements in CO2/H2 selectivity over the unmodified polymer at 37 oC along with promising results at elevated temperatures. In addition to performance, the study included examining the choice of polymeric supports on performance and membrane stability in more realistic operating conditions. Also included in this study was an evaluation of novel approaches to incorporate the ionic liquid into polymer matrices to optimize the performance and stability of the membranes.« less
  • Novel supported polymeric liquid (SPL) membranes have been prepared and shown to be applicable for the separation of CO{sub 2} from mixtures with N{sub 2} at the elevated temperature encountered in flue gas. The membranes were fabricated by immobilizing polystyrene, polyethylene, and polydimethylsiloxane into the pores of borosilicate glass supports. At 250 C, the CO{sub 2} permeability and CO{sub 2}/N{sub 2} separation factors were 3000--9000 barrer and 1.7--3.7, respectively. It was shown that polymers which have a lower T{sub g} or melting temperature than the operating temperature can be used as SPL membrane materials at elevated temperatures.
  • The advantages, disadvantages, and possible applications of macrocycle-mediated bulk, emulsion, supported and hollow fiber liquid membranes have been investigated. The relative transport rates of the alkali metal cations and of Zn(II), Cd(II) and Hg(II) in single and competitive cation experiments are studied and compared in the different membrane types. The four membrane types demonstrate similar selectivities but significantly different cation fluxes under comparable conditions using analogous macrocyclic carriers. The degree of distribution of the macrocycle to the organic membrane which is necessary for significant transport varies dramatically among the membrane types, each of which requires unique solvent characteristics. In themore » experiments, either 18-crown-6, dicyclohexano-18-crown-6, or 4,4'(5)bis(1-hydroxyheptylcyclohexano)-18-crown-6 were incorporated into bulk (chloroform, methylene chloride), emulsion (toluene), supported (phenylhexane) and hollow fiber (phenylhexane or 1-octanol) liquid membranes with the membrane solvents shown in parentheses.« less