An Innovative Approach Characterising the Interactions Leading to Pitch Deposition

Vercoe, David; Stack, Karen; Blackman, Adrian J.; Yates, Brian F.; Richardson, Desmond

doi:10.1081/wct-200026562

Cited by 8 publications

(15 citation statements)

References 9 publications

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“…This effect can be stronger in mixtures with fatty acids, where hydrogen bonding between the electron-rich aromatic ring and the double bonds in fatty acids allow the hydrophilic groups to interact with the water molecules and thus increase solubility. [3] The phase distribution of dehydroabietic acid was not much affected by the addition of calcium ( Figure 5), whereas the other resin acids were strongly affected (Figures 3 and 4, Table 1). Dehydroabietic was still practically entirely soluble in the pH range tested even at 10 mM Ca 2þ .…”

Section: Rfa In Pitch Emulsionmentioning

confidence: 90%

“…[1] The resin and fatty acids, RFAs, are generally enriched at the surface of the colloids; in alkaline environments their ionized carboxyl groups impart a negative charge to the particle and thus enable their electrostatic dispersal. [2,3] RFAs are also found in the water phase in dissolved form, either ionized or, to a small degree, protonated.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Calcium on the Phase Distribution of Resin and Fatty Acids in Pitch Emulsions

MacNeil

Sundberg

Vähäsalo

et al. 2011

Journal of Dispersion Science and Technology

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Resin and fatty acids (RFAs) play a key role in deinking processes of recycled fiber after precipitation by calcium. The distribution of RFAs between the lipophilic/colloidal phase and the water phase, here called pK lw , was determined by gas chromatography for different emulsions of TMP pitch and fatty acid soaps in the presence of calcium ions. Resin acids were at least partially dissolved at alkaline conditions even at high calcium ion concentrations, while fatty acids were only slightly soluble. The structure of the component was an important factor, along with the calcium content present which made fatty acids practically insoluble.

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Section: Rfa In Pitch Emulsionmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Effect of Calcium on the Phase Distribution of Resin and Fatty Acids in Pitch Emulsions

MacNeil

Sundberg

Vähäsalo

et al. 2011

Journal of Dispersion Science and Technology

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“…tails (Nyrén and Back 1958a,b;McLean et al 2005a;Strand 2013;Pashkovskaya et al 2018). The fatty acids naturally present in wood materials tend to be dominated by 16-carbon or 18-carbon chain length and either one, two, or three C=C double bonds (Vercoe et al 2004). The dissociation of such fatty acids is often suppressed until the pH is raised two or three units higher than such compounds as acetic acid, especially at a relatively low ionic strength of solution (McLean et al 2005a).…”

Section: Importance Of the Topicmentioning

confidence: 99%

“…There are three modes by which fatty acid moieties have been proposed to form stable pairs (Kanicky and Shah 2003;Vercoe et al 2004). It appears that one such mode, if formed, is likely to have an effect on the pKa values of fatty acids.…”

Section: Dimerization Of Carboxylic Acids (Pre-micellization and Headmentioning

confidence: 99%

“…A structure such as that shown in Part A might be hypothesized as an initial meta-stable step leading to the formation of a micelle. Though the structure makes logical sense, there (Vercoe et al 2004). Such paring could be expected to play a significant role when the protonated form of carboxylic acid is dissolved in a nonpolar solvent.…”

Section: Dimerization Of Carboxylic Acids (Pre-micellization and Headmentioning

confidence: 99%

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Self-assembly of alkyl chains of fatty acids in papermaking systems: A review of related pitch issues, hydrophobic sizing, and pH effects

Hubbe

McLean

Stack

et al. 2020

BioRes

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This review article considers the role of fatty acids and the mutual association of their long-chain (e.g. C18) alkyl and alkenyl groups in some important aspects of papermaking. In particular, published findings suggest that interactions involving fatty acids present as condensed monolayer films can play a controlling role in pitch deposition problems. Self-association among the tails of fatty acids and their soaps also helps to explain some puzzling aspects of hydrophobic sizing of paper. When fatty acids and their soaps are present as monolayers in papermaking systems, the pH values associated with their dissociation, i.e. their pKa values, tend to be strongly shifted. Mutual association also appears to favor non-equilibrium multilayer structures that are tacky and insoluble, possibly serving as a nucleus for deposition of wood extractives, such, as resins and triglyceride fats, in pulp and paper systems.

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Removal of wood extractives as pulp (pre-)treatment: a technological review

2021

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Wood extractives usually do not exceed five percent of dry wood mass but can be a serious issue for pulping as well as for the pulp itself. They cause contamination and damages to process equipment and negatively influence pulp quality. This paper addresses not only the extractives-related problems but also different solutions for these issues. It is an extensive review of different technologies for removing wood extractives, starting with methods prior to pulping. Several wood yard operations like debarking, knot separation, and wood seasoning are known to significantly decreasing the amount of wood extractives. Biological treatment has also been proven as a feasible method for reducing the extractives content before pulping, but quite hard to handle. During pulping, the extractives reduction efficiency depends on the pulping method. Mechanical pulping removes the accessory compounds of wood just slightly, but chemical pulping, on the other hand, removes them to a large extent. Organosolv pulping even allows almost complete removal of wood extractives. The residual extractives content can be significantly reduced by pulp bleaching. Nevertheless, different extraction-based methods have been developed for removing wood extractives before pulping or bleaching. They range from organic-solvent-based extractions to novel processes like supercritical fluid extractions, ionic liquids extractions, microwave technology, and ultrasonic-assisted extraction. Although these methods deliver promising results and allow utilization of wood extractives in most cases, they suffer from many drawbacks towards an economically viable industrial-scale design, concluding that further research has to be done on these topics. Graphical abstract

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An Innovative Approach Characterising the Interactions Leading to Pitch Deposition

Cited by 8 publications

References 9 publications

Effect of Calcium on the Phase Distribution of Resin and Fatty Acids in Pitch Emulsions

Effect of Calcium on the Phase Distribution of Resin and Fatty Acids in Pitch Emulsions

Self-assembly of alkyl chains of fatty acids in papermaking systems: A review of related pitch issues, hydrophobic sizing, and pH effects

Removal of wood extractives as pulp (pre-)treatment: a technological review

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