COMPARISON OF SAMPLE PRE-TREATMENT METHODS ON FLOW CYTOMETRY MEASUREMENT OF MECHANICAL PULP

摘要

Analytics of small micro scale particles from pulp and paper processes is of continuous interest. However, practical methods to analyze the size, shape or surface properties of particles from a process stream are presently scarcely available. In this study, Flow Cytometry (FCM) was used to determine the concentration of colloidal material in mechanical pulp. FCM measures particles one by one as the sample is fed through a flow cuvette illuminated by a laser beam. Light scattered or emitted by the particles is detected by scatter and fluorescence channels, respectively. Sample pre-treatments are used to remove fibres from pulp, usually either by centrifugation or by Britt Dynamic Drainage Jar (DDJ) Filtration. The purpose of this study was to compare how these two commonly used sample pre-treatment methods affect FCM detection of colloidal pitch in mechanical pulp. Similar population of colloidal pitch particles was observed with both sample pre-treatment methods. In contrast, a population of fines was observed primarily when using Britt DDJ Filtration. Depending on the research scope, both pre-treatment methods can be utilized. For measuring colloidal particles only, centrifugation is the better choice, while Britt DDJ Filtration is a more suitable method when analyzing colloidal particles with fines present.