The effects of pH on the accumulation of fines, dissolved and colloidal substances in the short circulation of papermaking

Jani Lehmonen, Juha Houni, P. Raiskinmäki, L. Vähäsalo, Antti Grönroos

Research output: Contribution to journalArticleScientificpeer-review

7 Citations (Scopus)

Abstract

The fluctuation of pH makes a process more sensitive to unwelcome precipitates and web breaks. pH is also one of the major factors that affect the solubility of different substances. For these reasons, accumulation studies of water circulation in a papermaking process were carried out. Accumulation studies were performed using a two-stage refined thermomechanical pulp (TMP) and a wide range of pH levels. The process temperature was 50°C and the average pH levels were from 4 to 10. pH has a significant effect on the amount of dissolved and colloidal material in the filtrate water. At high pH, accumulation was generally slightly higher than at low pH. The rheology of the filtrate water also changes considerably as a function of pH, and thereby has an effect on the water removal in a papermaking process. The results indicated that depending on the shear rate level of the filtration process the viscosity change is in the order often percent. So, rheological properties of filtrate water may play an important role in the water removal process. The results indicate that the dissolution of resin acid as a result of an increase of pH lowers the viscosity of the filtrates.
Original languageEnglish
Pages (from-to)46-52
Number of pages7
JournalJournal of Pulp and Paper Science
Volume35
Issue number2
Publication statusPublished - 2009
MoE publication typeA1 Journal article-refereed

Keywords

  • papermaking
  • water circulation
  • pH

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