Automated Membrane Characterization: In-situ Monitoring of the Permeate and Retentate Solutions using a 3D Printed Permeate Probe Device

19 September 2024, Version 2
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

Self-driving laboratories and automated experiments can accelerate the design workflow and decrease errors associated with experiments that characterize membrane transport properties. Within this study, we use 3D printing to design a custom stirred cell that incorporates inline conductivity probes in the retentate and permeate streams. The probes provide a complete trajectory of the salt concentrations as they evolve over the course of an experiment. Here, automated diafiltration experiments are used to characterize the performance of commercial NF90 and NF270 polyamide membranes over a predetermined range of KCl concentrations from 1-100 mM. The measurements obtained by the inline conductivity probes are validated using offline post-experiment analyses. Compared to traditional filtration experiments, the probes decrease the amount of time required for an experimentalist to characterize membrane materials by more than 50× and increase the amount of information generated by 100×. Device design principles to address the physical constraints associated with making conductivity measurements in confined volumes are proposed. Overall, the device developed within this study provides a foundation to establish high-throughput, automated membrane characterization techniques.

Keywords

Diafiltration
High-throughput membrane testing
3D printing
Nanofiltration
Parameter Estimation
Fisher information matrix

Supplementary materials

Title
Description
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Title
Supplementary Information - Permeate Probe
Description
The SI includes a discussion of the printing and assembly of the permeate probe device. Tables to compare the time requirements associated with filtration and diafiltration experiments, parameter estimates for diafiltration experiments, and MBDOE optimality criteria. The supplementary figures show the flow path in the permeate probe device, the effect of mixing in the permeate probe reservoir, calibration curves for the conductivity probe in confined volumes, and experimental data/methods to regress the residence time of the permeate probe reservoir.
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Supplementary weblinks

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