Development of a new gas sensor for binary mixtures based on the permselectivity of polymeric membranes : application to oxygen/nitrogen mixture

Abstract

A new oxygen/nitrogen gas concentration sensor is described in this paper. This new sensor is based on the permselectivity of a membrane element. It is especially suited for the very low price market to determine the concentration of binary or pseudo-binary gas mixtures in the 0100% range.The sensor is made of a permselective membrane module whose permeate stream is linked to a needle valve. The feed composition is related to the permeate build-up pressure, measured using a pressure transducer. Poly(dimethylsiloxane) (PDMS) and poly(etherimide) (PEI) hollow fiber membranes were tested. The response curves for both membranes at different temperatures display a quasi-linear behavior. The PDMS membrane-based sensor enables continuous and rapid oxygen analysis (t095% = 50 s) with a reproducible and long-term stable signal ((O2) = 2.474 × 106 dm3 (STP) s1 m2 Pa1, s = 0.045 × 106, N = 10; (N2) = 1.173 × 106 dm3 (STP) s1 m2 Pa1, s = 0.010 × 106, N = 11) over 5.4 × 106 s. The absolute sensitivity of the PDMS-based sensor depends on the oxygen feed concentration ranging from 0.0329 to 0.450 MPa.A simple analytical model was developed and is presented here. Good agreement was obtained with the experimental results for both membranes.