Aggregation and destabilisation of colloidal wood pitch by calcium ions in TMP suspensions

A1 Originalartikel i en vetenskaplig tidskrift (referentgranskad)


Interna författare/redaktörer


Publikationens författare: Anders Strand, Anna Sundberg, Lari Vähäsalo, Bjarne Holmbom
Förläggare: AB SVENSK PAPPERSTIDNING
Publiceringsår: 2011
Tidskrift: Nordic Pulp and Paper Research Journal
Tidskriftsakronym: NORD PULP PAP RES J
Volym: 26
Nummer: 4
Artikelns första sida, sidnummer: 429
Artikelns sista sida, sidnummer: 437
Antal sidor: 9
ISSN: 0283-2631
eISSN: 2000-0669


Abstrakt

The colloidal stability of wood pitch against aggregation and destabilisation by CaCl2 was assessed in suspensions of unbleached and peroxide-bleached thermomechanical pulp (TMP). The experi-ments were conducted at different pulp consistencies, at both pH 5 and pH 8, to determine pitch aggregation in acidic and neutral papermaking processes using TMP.
The colloidal pitch had low affinity to TMP fibres in the absence of CaCl2. At pH 8, a higher concentration of CaCl2 was required to destabilise the colloidal pitch than at pH 5. Even low CaCl2-concentrations caused destabili-sation of colloidal pitch in suspensions of TMP at pH 5.
More pitch was destabilised by CaCl2 in suspensions of unbleached TMP than in suspensions of peroxide-bleached TMP. Resin acids were to a large extent found as stable calcium-soaps in the water phase at pH 8, even at high concentrations of CaCl2.
Water-soluble galactoglucomannans (GGM) stabilised pitch emulsions almost completely against calcium-induced aggregation both at pH 5 and 8. The colloidal stability of pitch in suspensions of TMP was not total, but was much higher when GGM was added, compared to when no GGM was added.


Nyckelord

Calcium, Colloidal pitch, Deposits, Galactoglucomannans, TMP, Wood resin

Senast uppdaterad 2019-15-12 vid 02:51