Terahertz Methods for Investigating the Liquid Transport Characteristics in Porous Media

Liquid transport in porous media is an important phenomenon in many scientific and engineering fields. Investigating the liquid transport process is crucial for gaining a better understanding of various important industrial processes, such as the disintegration of pharmaceutical tablets as well as the impregnation of catalyst supports and heterogenous catalysis. In this thesis, the terahertz methods, i.e. terahertz time-domain spectroscopy (THz-TDS) and terahertz pulsed imaging (TPI), were used as promising techniques to quantify the impact of the microstructure characteristics and formulation on the liquid transport process in two types of porous media, i.e. pharmaceutical and catalytic powder compacts. The terahertz methods were first used to investigate the liquid uptake and swelling in fast disintegrating tablets (FDTs) that were prepared from powder mixtures of either theophylline or paracetamol as a drug and either functionalised calcium carbonate (FCC) or microcrystalline cellulose (MCC) as a filler at different porosities. The terahertz results demonstrate the clear impact of porosity and formulation on the water transport and swelling kinetics of FDTs. The methodology was then extended to study the transport of water and 1-octanol in α-alumina powder compacts that were prepared at a range of different compaction forces, i.e. 7, 23, 40 and 58 kN, and heat treatment conditions, i.e. unfired and fired. The terahertz results reveal that both the microstructure characteristics and surface properties have an impact on the liquid transport in the alumina compacts. The results show the great potential of the terahertz methods to study the liquid transport characteristics of polymeric and ceramic porous media. Quantifying the individual disintegration mechanisms, i.e. liquid ingress and swelling, is crucial for improving the design of pharmaceutical tablets through understanding the effect of raw materials and processing on the disintegration process. The information on the liquid transport in catalytic materials is also important for developing the design of catalysts and enhancing their performance upon contact with the liquid.

Name dc:type.qualificationname

Doctor of Philosophy (PhD)

Level dc:type.qualificationlevel

Doctoral

Grantor dc:publisher.institution

University of Cambridge

Year dc:date.issued

2021

Author dc:creator

• Al-Sharabi, Mohammed

Advisor dc:contributor.advisor

• Zeitler, J Axel

• Porous media
• Pharmaceutical tablets
• Catalysts
• Terahertz
• Microstructure
• Liquid transport

Licence

• https://www.rioxx.net/licenses/all-rights-reserved/

Language dc:language

eng

DOI dc:identifier.doi

https://doi.org/10.17863/CAM.80875

OAI identifier oai:identifier

oai:www.repository.cam.ac.uk:1810/333451