Membrane inlet manometry for the measurement of water activity in aqueous and organic solutions

✍ Scribed by H. Degn; N.-U. Frigaard

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 368 KB
• Volume: 274
• Category: Article
• ISSN: 0003-2670
• DOI: 10.1016/0003-2670(93)80485-4

✦ Synopsis

Ah&act

An apparatus for contmuous measurement of water actlvlty IS described where a water permeable membrane 1s used to separate the sample from the vacuum of a contmuously pumped chamber When the sample contams no other component than water which permeates through the membrane at a sign&ant rate the steady state pressure m the vacuum chamber IS a function of the water actnnty of the sample A polypropylene terephthalate membrane was used which 1s highly permeable to water and virtually Impermeable to atmospheric gases and volahle orgamc hqmds The vacuum chamber IS pumped by a turbomolecular pump and the pressure 1s measured by a Penmng gauge The apparatus 1s cahbrated by the help of aqueous salt solutions of known water actlvlty Examples of measurements of water actnnty m bmary alcohol-water nuxtures are presented and compared with data from the literature