Search

Your search keyword '"Scales, Peter J"' showing total 211 results
Start Over Author "Scales, Peter J" Search Limiters Peer Reviewed
211 results on '"Scales, Peter J"'

10. Yielding and Flow in Aggregated Particulate Suspensions.

Author

Scales, Peter J., Usher, Shane P., Larsen, Maria Barmar, Stickland, Anthony D., Teo, Hui-En, de Kretser, Ross G., and Buscall, Richard

Abstract

The flow and consolidation of strongly flocculated particulate suspensions in water are common to a range of processing scenarios in the minerals, food, water and wastewater industries. Understanding the compressive strength or resistance to consolidation of these suspensions is relevant to processes such as filtration, centrifugation and gravity settling, where the compressive strength defines an upper boundary for processing. New data for the compressive strength of consolidating flocculated particulate suspensions in water, including alumina and calcium carbonate, are compared with earlier data from the literature and from our own laboratories for several systems, including two earlier sets of data for alumina. The three sets of data for the compressive strength of alumina agree well. Differences are noted for data measured in shear between our own laboratories and others. New data for the shear strength of AKP-30 alumina are also presented, and although the agreement is not as good, the difference is implied to be due to wall slip associated with a difference in measurement techniques. A simple nonlinear poro-elastic model of the compressive strength was applied to the eight sets of compressive strength data and was found to account for most features of the observed behaviour. The agreement strongly supports the mechanistic failure mode in compression for these systems to be one of simple strain hardening. The one feature that it does not account for without invoking a 'ratchet' is the irreversibility of consolidation. It is, however, suspected that wall adhesion might provide such a ratchet in reality, since wall adhesion has been neglected in the analysis of raw compressive strength until recently, notwithstanding the pioneering work of Michaels and Bolger (30). Overall, the data analysis and fitting presented herein indicate a new future for the characterisation of aggregated particulate suspensions in shear and compression whereby a limited data set in both compression and shear, albeit targeted across a wide concentration range, can now be used to predict comprehensive curves for the shear yield stress and compressive yield stress of samples using a simple poro-elastic model. The veracity of the approach is indicated through a knowledge that the behaviour of both parameters is scalar across a wide range of materials and across a wide range of states of aggregation. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

46. Sub-ppm determination of perfluorinated carboxylic acids in solution by UV-vis high-performance liquid chromatography through solid phase extraction.

Author

Pang, Hongjiao, Allinson, Mayumi, and Scales, Peter J.

Subjects
HIGH performance liquid chromatography, CARBOXYLIC acids, DETECTION limit, ACID solutions, HUMUS, SOLID phase extraction
Abstract

This study investigated a novel and sensitive analytical method based on a simple heat-based derivatization using 3-bromoacetyl coumarin as the reagent and analysis with a HPLC-UV system or just a UV-vis spectrometer to allow the sub-ppm determination of PFCAs in water solution with the potential for utilization in simple laboratories and field laboratory scenarios. A Strata-XAW cartridge was used for the solid phase extraction (SPE) procedure and higher than 98% recoveries were obtained. The derivatization condition showed that a high efficiency of peak separation was obtained with obviously different retention time among various PFCAs derivatives using HPLC-UV analysis. The derivatization stability and repeatability showed favorable results with stable derivatized analytes for ≤12h and a relative standard deviation (RSD) of <2% for all repetitions. The limit of detection for the HPLC-UV analysis was between 0.1ppm and 0.5ppm. A satisfactory linearity response was found with R² >0.998 for all individual PFCA compounds. The limit of detection for simple UV-Vis analysis was <0.0003ppm to measure the presence of PFCAs. Contamination of standards with humic substances and measurement of industrial samples in a complex wastewater matrix showed no adverse effects on the accuracy of PFCA determination by using the developed methodology. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results