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Selective Separation Of Wood Components In Internal Process Waters Originating From Mechanical Pulping
Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering. Mittuniversitetet. (Surface and Colloid Engineering)ORCID iD: 0000-0002-0770-2086
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Dissolved and Colloidal substances (DSC) and metals are released from woodduring thermomechanical pulp (TMP) production. These components have atendency to accumulate in process waters, as the water circulation systems inintegrated paper mills are closed. Disturbances such as pitch depositions in thepaper machine (pitch problems), specks in the paper, decreased wet and drystrength, interference with cationic process chemicals, and impaired sheetbrightness and friction properties appear when DSC are present. Transition metalions such as manganese results in higher consumption of bleaching chemicals(hydrogen peroxide) and lowers the optical quality of the final product, andaddition of complexing agents, such as EDTA or DTPA, to prevent this is needed.The never ending trends to decrease water consumption and increase processefficiency in pulp and paper production emphasizes that it is very important bothto know the effects of wood substances on pulping and papermaking and to beable to remove them in an efficient way. From a biorefinery point of view, DSCcomponents can be promising renewable raw materials for biofuels, bio‐basedchemicals and materials.In this thesis, a new approach using induced air flotation (IAF) without a cationicpolyelectrolyte addition for the removal of pitch and metal ions from mechanicalpulp mill process waters is presented. The induced air flotation of different processwaters is facilitated by the addition of a chelating surfactant and different foamingagents. The influence of the pH value, temperature and foaming agentconcentration on the flotation efficiency has been investigated. The investigations

presented show that the disturbing components can be removed from TMP presswater to a high extent. A 90% decrease in turbidity and a 91% removal of lipophilicextractives (i.e. resin and fatty acids, triglycerides, sterols and steryl esters) fromunbleached and bleached TMP process water can be obtained by addition of acationic surfactant as foaming agent during flotation. Lower amount of foamingagent is needed to purify efficiently bleached TMP process water, than unbleached.Additionally, fibres located in TMP press water are not removed with the foamfraction but purified. A retained concentration of hydrophilic extractives (i.e.hemicelluloses and lignans) in the process water indicates that the flotation isselective. Moreover, by introduction of a new recoverable surface activecomplexing agent, a chelating surfactant, manganese ions in the form of chelatescan be successfully removed from the pulp fibres and separated from the processwater in the same flotation process. Furthermore, from the purified unbleachedTMP process water a 90% recovery of dissolved hemicelluloses by anti‐solventprecipitation was obtained.The findings presented above indicate new possibilities for the internal watercleaning stage to decrease DSC emissions to recipient and for recovery of valuableraw materials from purified process water if flotation technology is applied in anintegrated mechanical pulp mill.

Place, publisher, year, edition, pages
Sundsvall: Mid Sweden University , 2014. , 178 p.
Series
Mid Sweden University doctoral thesis, ISSN 1652-893X ; 184
Keyword [en]
flotation, foaming agents, chelating surfactant, TMP process water, pitch control, internal cleaning stage, hemicellulose recovery, anti‐solvents, solvents, precipitation
National Category
Polymer Chemistry
Identifiers
URN: urn:nbn:se:miun:diva-22244ISBN: 978-91-87557-45-3 (print)OAI: oai:DiVA.org:miun-22244DiVA: diva2:727823
Public defence
2014-05-28, O102, Holmgatan 10, Sundsvall, 12:33 (English)
Opponent
Supervisors
Projects
FORE
Funder
Knowledge Foundation, 2180
Available from: 2014-06-27 Created: 2014-06-23 Last updated: 2015-03-13Bibliographically approved
List of papers
1. Brightness development of a hydrogen peroxide bleached spruce TMP. Comparisons of pre-treatments with DTPA and a separable chelating surfactant
Open this publication in new window or tab >>Brightness development of a hydrogen peroxide bleached spruce TMP. Comparisons of pre-treatments with DTPA and a separable chelating surfactant
Show others...
2012 (English)In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, no 1, 50-55 p.Article in journal (Refereed) Published
Abstract [en]

In this investigation a new type of recoverable complexing agent (chelating surfactant) has been compared with a conventional complexing agent; diethylenetriamine pentaacetic acid (DTPA), in the metal ion sequestering of thermomechanical pulps (TMP) to be hydrogen peroxide bleached. After different degrees of washing of the pulps, bleaching experiments at different total alkali charges were performed with and without sodium silicate additions, and the ISO brightness of hand-made sheets was measured. The residual hydrogen peroxide in the bleaching liquor was also determined. No significant difference in either the brightness development or the residual hydrogen peroxide content could be detected between the pulps treated with equivalent molar ratios of the different complexing agents. Furthermore, the recovery of the chelating surfactant-manganese complexes from laboratory made white water by froth flotation was also studied. Two different foaming agents; sodium dodecyl sulphonate (SDS) and dimethyldodecylamine oxide (DDAO), were tested in the froth generation. After an addition of 160 ppm of DDAO, more than 80% of the manganese chelates could be recovered in the foam, containing 3% of the initial water mass.

Keyword
Chelating surfactant; DTPA; Flotation; Hydrogen peroxide bleaching; Manganese; Thermomechanical pulp
National Category
Chemical Engineering
Identifiers
urn:nbn:se:miun:diva-16093 (URN)10.3183/NPPRJ-2012-27-01-p050-055 (DOI)000311019900006 ()2-s2.0-84860145718 (Scopus ID)
Available from: 2012-04-17 Created: 2012-04-17 Last updated: 2017-12-07Bibliographically approved
2. Removal of lipophilic extractives and manganese ions from spruce TMP waters in a customized flotation cell
Open this publication in new window or tab >>Removal of lipophilic extractives and manganese ions from spruce TMP waters in a customized flotation cell
2012 (English)In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 7, no 2, 2376-2392 p.Article in journal (Refereed) Published
Abstract [en]

The influence of a chelating surfactant, different foaming agents, cationic polyelectrolytes, pH value, and temperature on the purification efficiency of process waters from a mechanical pulp mill has been studied by flotation in a 1 L customized unit. Turbidity measurements and gas chromatography (GC) were carried out to determine the removal and characteristics of dissolved and colloidal substances (DisCo). The manganese ion content in the process waters before flotation and the metal chelate removal capacity by flotation were determined by Inductively Coupled Plasma (ICP) and Atomic Absorption Spectrometry (AAS) measurements. It was found that a 99% removal of complex bound manganese ions and a 94% decrease in turbidity of the TMP water produced at the laboratory can be achieved in a single-stage flotation with a chelating surfactant and a foaming agent. Furthermore, a 91% decrease in turbidity, the removal of up to 96% of resin and fatty acids, and 93% of triglycerides from TMP water can be obtained after application of a foaming agent.

Keyword
Chelating surfactant; Extractives; Flotation; Foaming agents; Internal cleaning stage; Purification
National Category
Chemical Engineering
Identifiers
urn:nbn:se:miun:diva-16094 (URN)000306481700077 ()2-s2.0-84863812526 (Scopus ID)
Available from: 2012-04-17 Created: 2012-04-17 Last updated: 2017-12-07Bibliographically approved
3. Use of a Voith flotation cell for removal of lipophilic extractives and Mn ions from spruce thermomechanical pulping process waters
Open this publication in new window or tab >>Use of a Voith flotation cell for removal of lipophilic extractives and Mn ions from spruce thermomechanical pulping process waters
2012 (English)In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 7, no 3, 2784-2126 p.Article in journal (Refereed) Published
Abstract [en]

The effects of a chelating surfactant and different foaming agents on the efficiency of cleaning process waters from a thermomechanical pulp (TMP) mill were studied in a Voith flotation cell. Turbidity measurements and gas chromatography were used to determine the removal extent and characteristics of dissolved and colloidal substances (DisCo). The metal ion content in the process waters before flotation and the metal chelate removal after flotation were determined using inductively coupled plasma-optical emission spectrometry (ICP-OES). FiberLab (TM) equipment was used to characterize changes in the size of fibers present in the process waters. The results indicate that a decrease in turbidity of up to 91% and the removal of 80% of lipophilic extractives in the TMP water could be obtained using a single-stage flotation unit. Furthermore, the foam fraction was within 5% of the initial volume, and 100% of the Mn2+/chelating surfactant complex added to the TMP water was removed.

Keyword
Flotation; Extractives; Foaming agents; Chelating surfactant; Purification; Internal cleaning stage
National Category
Chemical Engineering
Identifiers
urn:nbn:se:miun:diva-16095 (URN)000307639900007 ()2-s2.0-84865758132 (Scopus ID)
Projects
FORE/Återvinn
Available from: 2012-04-17 Created: 2012-04-17 Last updated: 2017-12-07Bibliographically approved
4. Selective froth flotation of pitch components from spruce TMP process water
Open this publication in new window or tab >>Selective froth flotation of pitch components from spruce TMP process water
Show others...
2012 (English)In: Appita journal, ISSN 1038-6807, Vol. 65, no 4, 337-346 p.Article in journal (Refereed) Published
Abstract [en]

Selective removal of dissolved and colloidal pitch components from an unbleached thermomechanical pulp (TMP)

pressate by addition of a cationic foaming agent, dodecyltrimethylammonium chloride (DoTAC), and subsequent froth

flotation was assessed. The experiments were conducted with varying pH, temperature, and concentrations of DoTAC

and calcium. The concentrations of pitch components, lignans, and dissolved polysaccharides were determined

before and after flotation.

All pitch components were removed more efficiently by flotation at pH 5 and 3.5 than by flotation at pH 7.6. Resin

and fatty acids were removed to a higher degree than neutral pitch substances at all the tested pH levels. Most of the

water-soluble uronic acids and galactoglucomannans stayed in the TMP water after flotation.

Froth flotation with DoTAC was an effective way of selectively removing colloidal and dissolved pitch. Removal of pitch,

especially of resin acids, at an early stage should be beneficial to the overall papermaking process.

Keyword
Colloidal pitch, wood resin, mechanical pulp, flotation, anionic trash
National Category
Physical Chemistry
Identifiers
urn:nbn:se:miun:diva-17243 (URN)000309898500026 ()
Projects
Fore
Funder
EU, European Research Council
Available from: 2012-11-02 Created: 2012-10-26 Last updated: 2017-12-07Bibliographically approved
5. Recovery of water-soluble hemicelluloses from TMP process water after selective flotation.
Open this publication in new window or tab >>Recovery of water-soluble hemicelluloses from TMP process water after selective flotation.
2013 (English)In: The 17th International Symposiumon on Wood, Fiber and Pulping Chemistry, 2013Conference paper, Oral presentation with published abstract (Refereed)
National Category
Chemical Engineering
Identifiers
urn:nbn:se:miun:diva-20746 (URN)
Conference
The 17th International Symposiumon on Wood, Fiber and Pulping Chemistry
Available from: 2013-12-17 Created: 2013-12-17 Last updated: 2014-06-27Bibliographically approved
6. Antisolvent precipitation of water-soluble hemicelluloses from TMP process water
Open this publication in new window or tab >>Antisolvent precipitation of water-soluble hemicelluloses from TMP process water
2014 (English)In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 113, 411-419 p.Article in journal (Refereed) Published
Abstract [en]

During the thermomechanical pulping (TMP) of spruce, hemicelluloses (mainly galactoglucomannans, GGMs) are released into the process water at relatively low concentrations that are currently impossible to efficiently recover. This paper examines the recovery of hemicelluloses precipitated from TMP process water via solubility reduction by adding antisolvents such as methanol, ethanol, and acetone. The phase separation was monitored by turbidity measurements. Gravimetric analysis, FTIR, GC–MS, UV spectroscopy, and ICP-OES were used to determine the yield, purity, and composition of the precipitates. Gel permeation chromatography and pulsed field-gradient self-diffusion NMR were used to measure the molecular mass distribution of the precipitates. Acetone was found to be the most efficient antisolvent, giving the highest yield at the lowest addition. The contents of lipophilic extractives and lignin impurities were below 0.5% and 1.6%, respectively, and the metal content was approximately 2% in the precipitates obtained with acetone.

Keyword
Antisolvent precipitation, Flotation, Hemicelluloses, Process water, Recovery, Thermomechanical pulping
National Category
Chemical Engineering
Identifiers
urn:nbn:se:miun:diva-22315 (URN)10.1016/j.carbpol.2014.07.033 (DOI)000343613000052 ()2-s2.0-84907321202 (Scopus ID)
Available from: 2014-06-27 Created: 2014-06-27 Last updated: 2017-12-05Bibliographically approved

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