Comparison of the modes of action of stickies control chemicals in ONP/OMG deinked pulp

摘要

Many types of chemicals are used to control stickies formation and deposition in ONP/OMG deinked pulp. According to mill experience, their mechanism of action is based either on charge neutralization, dispersion, surface modification or emulsification. Although stickies deposit formation and composition has been extensively studied, there has not been a systematic comparison of the mechanism of action of the different types of stickies control chemicals. The objective of this work was to understand the type of chemical interaction occurring between stickies causing chemicals and control chemicals and also the specificity of these control chemicals for different types of DIP. In order to simulate mill conditions, DIP containing known amounts of typical contaminants causing stickies deposits were prepared with an untreated TMP, and treated with common stickies control chemicals: polyamine, poly-DADMAC, cationic modified starch, alkanolamide and polyvinyl alcohol. Stickies control chemicals were added to the pulp and pH, conductivity, zeta potential, and cationic demand were monitored for 5 to 15 minutes to determine to physico-chemical changes occurring to the pulp and contaminants. Results indicate that the chemical nature of detrimental components changes with repulping conditions, in particular the initial pH. At neutral or near-neutral pH, the contaminants are mechanically detached from fibres. In these low charge, near-zero zeta potential conditions, it was not possible to determine any effect specific to surfactants, non-ionic or cationic polymers. However, as the pH increased, more hydrolysis products were formed giving a highly anionic, highly negative zeta potential pulp in which cationic additives like polyamine and poly-DADMAC become increasingly effective.