Pitch fixative selection by capillary electrophoresis

Abstract

Wood pitch deposition has antagonised the papermaker for over two hundred years. Fixatives, chemistries which are used to attach wood resin to wood fibre, have been used to alleviate wood pitch deposition to varying degrees of success. This paper aims to present a new method by which fixatives can be evaluated at a molecular level in a short period of time. Capillary Electrophoresis (CE) is used in many industries, including pulp and paper, as an analytical technique for the separation of analytes under the application of an electric field whereby the differences in the electrophoretic mobilities of the analytes lead to their separation. This paper makes use of CE, not for its separation of analytes but for quantification of interactions between analytes and selectivity modifiers. Electrokinetic chromatography (EKC) is a variation of CE where a selectivity modifier is included in the electrolyte. In using wood resin fixatives as selectivity modifiers and wood resin components as analytes, we were able to determine their interactions at a variety of pHs and temperatures. The result of this development is the ability to recommend a given fixative chemistry for the unique pH, temperature and extractive composition of a given pulp and/or paper mill. Details of the methods, results and data interpretation are included in this paper.