Membrane Technology applied, among others, in processes such as Ultrafiltration (UF) and Nanofiltration (NF), has become an important part of biotechnological separation processes in recent decades. Its main feature, the morphology of the porous filters, leading to a “sieving mechanism” allows effective separation with high selectivity features and made in energy and environmental conditions very interesting.
Given the enormous development of membrane filters, it becomes necessary the growth in parallel of characterization techniques applied to such filters, as essential tools for both manufacturers and end-users or researchers.
In this sense we need to know most exactly possible, both functional and structural parameters of the membrane, all necessary for a proper choice of that with a view to a particular application.
The question we must face is: Is there a characterization method, by itself, giving us a clear and easily interpretable picture of the true structure and functionality of the filter?.
The answer to this question is obviously no. There are so many structural and functional parameters that contribute to the exact knowledge of the membrane, that there is no technique that can bring us all this wealth of information.
From the industrial and commercial standpoints, the parameter most used and required, in view of possible applications of the filters, it is the molecular weight cut-off (MWCO), although it is clear that by itself is not a definitive tool for choosing a membrane filter.
SMAP® group long experience in membrane characterization allows us to conclude that porosimetric techniques give interesting information related to the size and size distribution of the pores present in a membrane, information that can be conveniently checked against functional aspects of it.
In this sense, we can consider that Liquid-liquid displacement porosimetry (LLDP) is the most promising porosimetric technique in the range of Ultrafiltration, thus giving us important information about these filters.
Table of Contents
1. OVERVIEW OF MEMBRANE SCIENCE AND TECHNOLOGY
1.1 INTRODUCTION
1.2 MEMBRANE MARKET
1.3 FUNDAMENTALS OF MEMBRANES
1.3.1 Definition and Classification
1.3.2 Membrane Module Design
1.3.3 Membrane Material
1.4 MEMBRANE PROCESSES
1.4.1 Pressure Driven Membrane Processes
1.4.2 Concentration Gradient Driven Processes
1.4.3 Electrical Potential Driven Membrane Processes
1.4.4 Temperature Gradient Driven Membrane Processes
1.5 CHARACTERIZATION OF MEMBRANES
1.5.1 Characterization Methods
1.5.2 Methods of Liquid Penetration
1.5.2.1 Fundamentals
1.5.2.2 Bubble Point Method
1.5.2.3 Fluid Displacement
-Air Liquid Displacement
-Liquid-Liquid Displacement
1.6 CONCLUSIONS
1.7 REFERENCES
2. DEVELOPMENT AND OPTIMIZATION OF A LIQUID-LIQUID DISPLACEMENT POROMETER DEVICE
2.1 HISTORICAL
2.2 LLDP ANALYSIS FUNDAMENTALS
2.2.1 Grabar-Nikitine Algorithm
2.3 AUTOMATED LLDP POROSIMETER
2.3.1 LLDP Setup
2.3.2 Porosimetric Liquids Preparation
2.3.3 LLDP Analysis
2.3.4 Data Analysis and Treatment
2.4 CONCLUSIONS
2.5 REFERENCES
3. Paper one Characterization of UF membranes by liquid–liquid displacement porosimetry
4. Paper two Characterisation of polymeric UF membranes by liquid–liquid displacement porosimetry
5. Paper three Liquid-liquid displacement porosimetry for the characterization of virus retentive membranes.
6. Paper four Liquid-liquid displacement porometry to estimate the molecular weight cut-off of ultrafiltration membranes
7. CONCLUSIONES / CONCLUSIONS
Research Objectives & Topics
The primary objective of this doctoral thesis is to enhance the Liquid-Liquid Displacement Porosimetry (LLDP) technique and optimize its application for analyzing commercial porous filters. The work focuses on automating existing setups, verifying optimal working conditions, and establishing theoretical correlations between membrane structure and industrial performance data.
- Automation and optimization of LLDP equipment and software.
- Characterization of Ultrafiltration (UF) and Nanofiltration (NF) membranes.
- Correlation of structural pore information with functional performance indicators like Molecular Weight Cut-Off (MWCO).
- Development of standardized protocols for reliable membrane testing.
- Application to virus retentive membranes and assessment of filtration performance.
Excerpt from the Book
1.1 INTRODUCTION
Membrane science and technology have seen the rationalization of production systems in the last decades. Their intrinsic characteristics of efficiency, operational simplicity and flexibility, relatively high selectivity and permeability for the transport of specific components, low energy requirements, good stability under a wide spectrum of operating conditions, environment compatibility, easy control and scale-up; have been confirmed in a large variety of applications and operations, both in liquid and gas phases and in a wide spectrum of operating parameters such as pH, temperature, pressure, etc. The possibility of using membrane systems as well as tools for a better design of chemical reactions is becoming attractive and realistic. For biological applications, synthetic membranes provide an ideal mechanical support due to their available surface area per unit volume.
Membranes and membrane processes were first introduced as an analytical tool in chemical and biomedical laboratories; they developed very rapidly into industrial products and methods with significant technical and commercial impact. Today, membranes are used on a large scale to produce potable water from sea and brackish water, to clean industrial effluents, to recover valuable constituents, to concentrate, purify, or fractionate macromolecular mixtures in food and drug industries, as well as to separate gases and vapours in petro-chemical processes. Membranes are also key components in energy conversion and storage systems, in chemical reactors, artificial organs, and in drug delivery devices. The membranes used in the various applications differ widely in their structure, in their function and the way in which they operate, being particularly attractive tools for the separation of molecular mixtures.
Summary of Chapters
1. OVERVIEW OF MEMBRANE SCIENCE AND TECHNOLOGY: Provides a comprehensive review of membrane science, markets, material classification, and existing characterization techniques used in the industry.
2. DEVELOPMENT AND OPTIMIZATION OF A LIQUID-LIQUID DISPLACEMENT POROMETER DEVICE: Details the engineering improvements, algorithm development, and automated setup created to enhance the accuracy and reproducibility of LLDP measurements.
3. Paper one Characterization of UF membranes by liquid–liquid displacement porosimetry: Presents the initial validation of the LLDP technique using various polysulfone and polycarbonate membranes to determine pore size distributions.
4. Paper two Characterisation of polymeric UF membranes by liquid–liquid displacement porosimetry: Extends the characterization to different series of commercial polymeric membranes, comparing results with other methods.
5. Paper three Liquid-liquid displacement porosimetry for the characterization of virus retentive membranes: Investigates the specific application of LLDP to characterize virus retentive membranes and correlates findings with phage retention data.
6. Paper four Liquid-liquid displacement porometry to estimate the molecular weight cut-off of ultrafiltration membranes: Focuses on establishing a methodology to estimate MWCO values for UF membranes using structural data obtained via LLDP.
7. CONCLUSIONES / CONCLUSIONS: Summarizes the key achievements of the research, including the successful automation of the device and the establishment of LLDP as a reliable tool for membrane structural and functional characterization.
Keywords
Ultrafiltration, Nanofiltration, Membrane Characterization, Liquid-Liquid Displacement Porosimetry, LLDP, Pore Size Distribution, MWCO, Molecular Weight Cut-Off, Porosity, Virus Retentive Membranes, Polymeric Membranes, Membrane Modules, Permeability, Filtration, Membrane Science.
Frequently Asked Questions
What is the core focus of this doctoral thesis?
The thesis focuses on improving and automating the Liquid-Liquid Displacement Porosimetry (LLDP) technique to provide a reliable, accurate, and standardized method for characterizing the structural properties of commercial ultrafiltration and nanofiltration membranes.
What are the primary themes covered in the research?
Key themes include membrane material science, the physics of fluid displacement in porous media, the automation of measurement hardware and data analysis software, and the correlation of structural pore data with operational performance parameters.
What is the main research goal?
The primary goal is to establish LLDP as a standard, non-destructive, and efficient characterization technique that can estimate membrane performance metrics like Molecular Weight Cut-Off (MWCO) and virus retention capability without needing time-consuming retention experiments.
Which scientific methods are utilized?
The study employs LLDP as the central characterization technique, complemented by scanning electron microscopy (SEM) for imaging, and various mathematical models, specifically the Cantor and Hagen-Poiseuille equations, to analyze pore size distributions and permeability.
What does the main body of the work cover?
It includes a comprehensive literature review of membrane science, a detailed technical description of the automated LLDP setup and the Grabar-Nikitine algorithm, and a series of experimental studies involving various commercial membranes to validate the technique.
Which keywords best describe this work?
Essential terms include Ultrafiltration, LLDP, Pore Size Distribution, Membrane Characterization, MWCO, Virus Retentive Membranes, and Fluid Displacement.
How does LLDP compare to gas-based porometry?
Unlike gas-liquid porometry, which requires extremely high pressures that can damage small pores in ultrafiltration membranes, LLDP uses a liquid-liquid interface, allowing for accurate characterization at much lower, non-destructive pressures.
Can LLDP predict the Molecular Weight Cut-Off (MWCO)?
Yes, one of the significant contributions of this thesis is the development of a protocol that correlates structural pore size distributions derived from LLDP data with operational MWCO values, offering a much faster alternative to traditional solute retention tests.
- Arbeit zitieren
- René Israel Peinador Dávila (Autor:in), 2013, Characterization of Ultra and Nanofiltration Commercial Filters by Liquid-liquid Displacement Porosimetry, München, GRIN Verlag, https://www.grin.com/document/268782
