I obtained my Bachelor from the Universiti Sains Malaysia and a PhD from the University of Melbourne in 1989. I have over 150 journal publications and more than 50 refereed conference publications. I am a member of the top 2% world scientists in 2019 and 2021 ranked by Stanford University. Some of my research results and data on colloidal forces-rheology in particular steric and DLVO forces, were reproduced in two well-regarded chemical Engineering Textbooks; Rheology and Structure of Complex Fluids (1999) and Colloidal Suspension Rheology (2012). I have a mathematical model named after me for describing the ageing behaviour of thixotropic suspensions and clay gels (deKretser and Boger, Rheol Acta 2001).  More recently we found that i) electrostatic double layer (EDL) repulsive force governs the development of the 3D network structure of clay gel and is responsible for the time-dependent behaviour (Langmuir 2018) and ii) microstructure of monodisperse nanodisotic Laponite gel was formed from sheets instead of disks contradicting prevailing model and understandings (PCCP 2018). Based these and follow-up studies, substantive revisions were made to the knowledge and understandings of dry clay and gel properties that had been acquired over the past 80 years (CSA 2021). I have now provided substantive evidence to show that the EDL repulsive force is responsible for the time-dependent behaviour of clay gels in structural rejuvenation mode (JPC-B 2024). Only a small amount of salt (0.01M KCl) caused the edge-face bonding process to speedup markedly and the gel to strengthen significantly. This hastened structural rejuvenation process greatly (JCP 2024). Addition of pyrophosphate additive can slow down the bonding process of these salt-treated gels. 

I am a teaching and research academic. Currently I teach two units; i) Reaction Engineering and ii) Particle Mechanics and Solids Handling.  I also work as a academic program accreditor for IChemE and am a Fellow of IChemE.

In research I supervise postgraduate students working on various areas of suspension rheology and processing. Here are some of the more recent projects

i) Surface chemistry, microstructure and rheology of thixotropic clay gels with very different morphology

ii) Reducing viscosity and water usage in iron ore processing and the mining of iron ore from tailings 

iii) Fragmentation kinetic function of polymer bridged flocs via PB modelling and the matching of computed and experimental particle size distribution.

I exploit surface chemistry tools to regulate the surface forces in order to control the rheology and optimise slurry processing.

Problems encountered and solved:
I) solve gelation problem in the production of ammonium phosphate slurries
ii) reduce the pumping cost of mineral/tailings slurries with low cost composite additives
iii) enhance the performance clay/mineral separation in iron ore slurries.

My current areas of research focus are:

i) Surface forces, microstructure and rheology of thixotropic clay gels,

ii) Mining of iron ore from tailings, to minimise water use and reduce concentrated tailings viscosity for transport. 

iii) Hydrometallurgical methods of enhancing rare Earth Metal extraction.

iv) Population balance of polymer bridged flocs.

I have received ARC Linkage, Discovery and LIEF grants over the past 20 years. I have also received funding from industry such as OSD pty ltd, RoyHill, QNI, WMC Fertilizers, Zinifex Century and a few others over the years.

My research generates new fundamental and applied knowledge that can be used to solve industrial suspension problems in rheology, thickening and consolidation, flotation and other hydrometallurgical processes. Clay suspension processing problems are of particular interest to me. Over the past 10 years, I have conducted extensive research on surface chemistry, rheology, microstructure and ageing properties of a range of clays such as kaolin, bentonite, sodium and calcium montmorillonite, hectorite, sepiolite and Laponite.

Past and Present areas of Research Interests:

Relating molecular structure of adsorbed additives to surface forces in Colloidal Suspensions;
Surface chemistry, microstructure and rheology of clay and oxide suspensions;
Surface forces and Microstructure of thixotropic Clay Suspensions ;
Coal and biochar slurry fuel preparation;
Experimental and Population balance modelling studies of flocculation and flocs fragmentation;

Inverse problems in viscometery;

Tensiometry: a new method of surface tension determination from pendant drop profile;

Derivative spectroscopy-a more accurate method for determine 1st, 2nd, 3rd and higher order derivatives;

Chemical Kinetics and thermodynamics-using more accurately determined derivatives for fundumental kinetics and thermodynamic analysis.