![[logo] US EPA](http://www.epa.gov/epafiles/images/logo_epaseal.gif){kind=logo}
Membrane Development
Objectives:
To fabricate novel polymer/ceramic mixed membranes for dehydration of alcohol streams using pervaporation and perform a comparative study of commercially available dehydration membrane's separation efficiency at similar operating conditions.
Background:
During a pervaporation workshop held at EPA, the consensus selection among attendees was to focus on the dehydration of organic process streams (especially IPA/water separation). Although the dehydration of IPA is the most popular application of pervaporation, US still lags behind Europe in commercial applications. The project aims to use pervaporation, a membrane separation process, for dehydration of alcohol streams. Alcohols, in particular 2-propanol (isopropyl alcohol - IPA), are utilized in various industries as solvents and cleaning agents. Separation of alcohol streams when contaminated by water at certain concentrations becomes difficult due to the formation of azeotropic mixtures which complicates the standard distillation process. An easy, efficient recovery and reuse of alcohols is imperative in view of the process economics and to meet the strict new environmental regulations. Pervaporation helps in producing water-free alcohols, in a simple, and energy-effective way.
The main component of the pervaporation process is the membrane material which determines the selectivity and hence the separation properties of the process. The membrane can be tailored according to the specific separation needs of the process. The most common dehydration membrane reported in literature is prepared from poly vinyl alcohol (PVA) which is crosslinked before its use in pervaporation processes. Although PVA cross linked helps in reducing the swelling of the membrane on contact with water, it also reduces the resulting water flux during the separation process.
Progress:
In this project a novel polymer/ceramic mixed membrane will be used to effect the separation. Ceramics are being considered increasingly as attractive membrane materials due to their increased strength and resistance; here we aim to combine the desirable properties of the selective polymer (PVA) and the ceramic (silicon dioxide) to dehydrate alcohol waste streams. The idea behind incorporating silicon dioxide particles in the polymer matrix is to provide additional pathways for the transport of water. The polymer/ceramic mixed membranes being investigated in the present study contain a mixture of poly(vinyl alcohol)/amine polymer with angstrom sized silicon dioxide particles dispersed throughout the membrane matrix and cross linked using either maleic acid or gluteraldehyde. The resulting polymer/ceramic blended membranes are either homogenous or composite (thin layer on a backing), clear and loaded with as much as 30 wt% of silicon dioxide particles.
The two values used to define membrane performance are flux and selectivity; these two values are evaluated in a bench-scale pervaporation unit by varying the membrane type (i.e., changing the extent of ceramic content, type of cross linking agent in the membranes) feed temperature, flow-rate, concentrations, and permeate pressure.
Contact Information:
Primary Investigators: Dr. Leland Vane(513) 569-7799
vane.leland@epa.gov
Fax: (513) 569-7677
Postal Address:
26 West Martin Luther King Drive
Mail Stop 443
Cincinnati, Ohio 45268