Transport processes through track-etch membrane filters in a reagent delivery cell

Area of Science:

• Analytical Chemistry
• Membrane Science
• Chemical Engineering

Background:

• Accurate calibration of analytical instruments requires precise reagent preparation.
• On-line dilution systems offer advantages in automation and reduced sample/reagent consumption.
• Track-etch membranes provide controlled porosity for filtration and separation applications.

Purpose of the Study:

• To develop and evaluate a reagent delivery cell for on-line dilution of concentrated salt solutions using a track-etch membrane filter.
• To investigate the impact of system parameters (concentration, temperature, pressure) on dilution efficiency.
• To demonstrate the application of the cell for on-line calibration of an atomic absorption spectrometer.

Main Methods:

• Utilized a reagent delivery cell equipped with a track-etch membrane filter.
• Systematically varied stock solution concentration, temperature, and transmembrane pressure.
• Conducted permeation experiments with aqueous solutions of chlorides and sodium salts.
• Applied Fick's first law for mathematical estimation of flux rates.

Main Results:

• Achieved membrane filter fluxes ranging from 10 to 50 nL mm(-2) min(-1).
• Demonstrated high precision with relative standard deviations of 0.8% (within-day) and 1.9% (day-to-day).
• Confirmed a diffusion process governing salt permeation through the membrane.
• Calculated dilution factors agreed with measured values within 86% to 113% using Fick's first law.

Conclusions:

• The developed reagent delivery cell is effective for precise on-line dilution of salt solutions.
• The system shows potential for reliable on-line calibration of analytical instruments like atomic absorption spectrometers.
• Mathematical modeling using Fick's first law can accurately predict dilution performance.