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Papers by Juha Fiskari

The purpose of this research was to gain a better understanding of the phenomena affecting fiber ... more The purpose of this research was to gain a better understanding of the phenomena affecting fiber quality in oxygen delignification. Softwood kraft pulps were oxygen delignified to six different extents using different temperatures and alkali.charges as variables in a factorial experiment. Each of the oxygen-delignified pulp samples, as well as two brownstock samples, was subjected to conventional DEDED bleaching at a constant first-stage kappa factor. The fully bleached samples were then characterized in terms of fiber length and curl by image analysis and amorphous/crystalline cellulose ratio by CP/MAS 13 C-NMR.

Nordic Pulp & Paper Research Journal, Dec 1, 2012

Extended-impregnation kraft cooking (EIC) is a cooking concept that combines prolonged impregnati... more Extended-impregnation kraft cooking (EIC) is a cooking concept that combines prolonged impregnation with modern improved modified kraft cooking. In the current investigation, the EIC cooking of birch was studied in relation to conventional kraft cooking. Specifically, the reject content and carbohydrate yield retention when terminating at a high cooking kappa number were examined. It was demonstrated that EIC cooking reduced the reject content. Unexpectedly, a high cooking kappa number led to no increase in carbohydrate yield, possibly due to the chemical composition of birch wood and the EIC cook lab procedure. A large amount of liquor was withdrawn after the impregnation, resulting in a loss of dissolved xylan that otherwise could have redeposited on the fibres and contributed to the carbohydrate yield. The effects of EIC cooking on extended oxygen delignification, bleaching chemical requirement in a D(OP)DP sequence, and strength properties were also examined. Compared with conventional lab cooking, EIC cooking resulted in a lower bleaching chemical requirement and similar strength properties.

Nature Protocols, May 26, 2023

Chemical Engineering Research and Design

The Canadian Journal of Chemical Engineering

The Canadian Journal of Chemical Engineering, 2022

This work examines the effect of pH on the AOX formation in a D stage in an ECF light bleaching s... more This work examines the effect of pH on the AOX formation in a D stage in an ECF light bleaching sequence. Carbon dioxide was added to the pulp, generating a bicarbonate buffer system in situ and st ...

This laboratory research was undertaken to gain a better understanding of Acacia mangium and Euca... more This laboratory research was undertaken to gain a better understanding of Acacia mangium and Eucalyptus pellita and their feasibility as feedstock in acid sulfite pulping. The plantation-grown hard ...

Chemical Engineering Journal, 2022

Over the last few decades, the pulp and paper industry has drastically decreased the environmenta... more Over the last few decades, the pulp and paper industry has drastically decreased the environmental load associated to its effluents. Further decrease of the environmental load of effluents in a cost-effective way remains one of the most important challenges for a Kraft pulp mill. In this study, Kraft pulp mill effluent was subjected to the Fenton treatment in both a laboratory and pilot scale in order to remove Adsorbable Organic Halogen (AOX) and Dissolved Organic Carbon (DOC). Oxidation reduction potential (ORP) was measured to follow the progress of oxidation. Laboratory results showed removals of 89% and 42% of AOX and DOC, respectively, with 3500 mg L-1 of H2O2 and 50 mg L-1 of Fe(II). In the pilot experiments, 84% removal of AOX and 71% removal in DOC were achieved with 6000 mg L-1 of H2O2 and 200 mg L-1 of Fe(II). Good correlation between the consumption of remaining oxidant and the observed ORP leads to a possibility to measure the extent of removal of AOX and DOC directly d...

Powered by TCPDF (www.tcpdf.org) This material is protected by copyright and other intellectual p... more Powered by TCPDF (www.tcpdf.org) This material is protected by copyright and other intellectual property rights, and duplication or sale of all or part of any of the repository collections is not permitted, except that material may be duplicated by you for your research use or educational purposes in electronic or print form. You must obtain permission for any other use. Electronic or print copies may not be offered, whether for sale or otherwise to anyone who is not an authorised user. Fiskari, Juha; Vihelä, Tuomas; Ruuttunen, Kyösti; Ali-Rekola, Ville; Hautala, Sanna; Sixta, Herbert Cooking of dry high-lignin Eucalyptus camaldulensis chips followed by TCF bleaching with hydrogen peroxide

The purpose of this research was to gain a better understanding of the phenomena affecting fiber ... more The purpose of this research was to gain a better understanding of the phenomena affecting fiber quality in oxygen delignification. Softwood kraft pulps were oxygen delignified to six different extents using different temperatures and alkali.charges as variables in a factorial experiment. Each of the oxygen-delignified pulp samples, as well as two brownstock samples, was subjected to conventional DEDED bleaching at a constant first-stage kappa factor. The fully bleached samples were then characterized in terms of fiber length and curl by image analysis and amorphous/crystalline cellulose ratio by CP/MAS 13 C-NMR.

Nordic Pulp & Paper Research Journal, Dec 1, 2012

Extended-impregnation kraft cooking (EIC) is a cooking concept that combines prolonged impregnati... more Extended-impregnation kraft cooking (EIC) is a cooking concept that combines prolonged impregnation with modern improved modified kraft cooking. In the current investigation, the EIC cooking of birch was studied in relation to conventional kraft cooking. Specifically, the reject content and carbohydrate yield retention when terminating at a high cooking kappa number were examined. It was demonstrated that EIC cooking reduced the reject content. Unexpectedly, a high cooking kappa number led to no increase in carbohydrate yield, possibly due to the chemical composition of birch wood and the EIC cook lab procedure. A large amount of liquor was withdrawn after the impregnation, resulting in a loss of dissolved xylan that otherwise could have redeposited on the fibres and contributed to the carbohydrate yield. The effects of EIC cooking on extended oxygen delignification, bleaching chemical requirement in a D(OP)DP sequence, and strength properties were also examined. Compared with conventional lab cooking, EIC cooking resulted in a lower bleaching chemical requirement and similar strength properties.

Nature Protocols, May 26, 2023

Chemical Engineering Research and Design

The Canadian Journal of Chemical Engineering

The Canadian Journal of Chemical Engineering, 2022

This work examines the effect of pH on the AOX formation in a D stage in an ECF light bleaching s... more This work examines the effect of pH on the AOX formation in a D stage in an ECF light bleaching sequence. Carbon dioxide was added to the pulp, generating a bicarbonate buffer system in situ and st ...

This laboratory research was undertaken to gain a better understanding of Acacia mangium and Euca... more This laboratory research was undertaken to gain a better understanding of Acacia mangium and Eucalyptus pellita and their feasibility as feedstock in acid sulfite pulping. The plantation-grown hard ...

Chemical Engineering Journal, 2022

Over the last few decades, the pulp and paper industry has drastically decreased the environmenta... more Over the last few decades, the pulp and paper industry has drastically decreased the environmental load associated to its effluents. Further decrease of the environmental load of effluents in a cost-effective way remains one of the most important challenges for a Kraft pulp mill. In this study, Kraft pulp mill effluent was subjected to the Fenton treatment in both a laboratory and pilot scale in order to remove Adsorbable Organic Halogen (AOX) and Dissolved Organic Carbon (DOC). Oxidation reduction potential (ORP) was measured to follow the progress of oxidation. Laboratory results showed removals of 89% and 42% of AOX and DOC, respectively, with 3500 mg L-1 of H2O2 and 50 mg L-1 of Fe(II). In the pilot experiments, 84% removal of AOX and 71% removal in DOC were achieved with 6000 mg L-1 of H2O2 and 200 mg L-1 of Fe(II). Good correlation between the consumption of remaining oxidant and the observed ORP leads to a possibility to measure the extent of removal of AOX and DOC directly d...

Powered by TCPDF (www.tcpdf.org) This material is protected by copyright and other intellectual p... more Powered by TCPDF (www.tcpdf.org) This material is protected by copyright and other intellectual property rights, and duplication or sale of all or part of any of the repository collections is not permitted, except that material may be duplicated by you for your research use or educational purposes in electronic or print form. You must obtain permission for any other use. Electronic or print copies may not be offered, whether for sale or otherwise to anyone who is not an authorised user. Fiskari, Juha; Vihelä, Tuomas; Ruuttunen, Kyösti; Ali-Rekola, Ville; Hautala, Sanna; Sixta, Herbert Cooking of dry high-lignin Eucalyptus camaldulensis chips followed by TCF bleaching with hydrogen peroxide

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