Sensitivity enhancement in membrane separation flow injection analysis by ultrasound

Area of Science:

• Analytical Chemistry
• Separation Science
• Physical Chemistry

Background:

• Flow injection separation techniques are crucial for rapid chemical analysis.
• Pervaporation and gas-diffusion are membrane-based separation methods with specific applications.
• Ultrasound is explored as a potential enhancer for separation processes.

Purpose of the Study:

• To investigate the effect of ultrasound on gas-diffusion and pervaporation separation.
• To evaluate the efficiency of sonication for separating ammonia and aliphatic amines.
• To understand the mechanism behind ultrasound's influence on mass transfer in pervaporation.

Main Methods:

• Experimental investigation of gas-diffusion and pervaporation separation.
• Utilized ammonia and three aliphatic amines (propylamine, tri-ethylamine, di-n-butylamine) as model analytes.
• Applied sonication during the separation processes and measured mass transfer improvements.

Main Results:

• Sonication did not enhance gas-diffusion separation efficiency under experimental conditions.
• Pervaporation mass transfer showed significant improvement, up to 62%, with sonication.
• Ultrasound-induced surface rippling was identified as the likely cause for enhanced evaporation.

Conclusions:

• Ultrasonic pervaporation separation offers a promising enhancement for on-line flow injection analysis.
• This technique can potentially be extended to determine higher molecular mass volatile and semi-volatile analytes.
• The findings suggest applicability in analyzing 'dirty' samples, expanding the utility of pervaporation.