Arthur Ragauskas | University of Tennessee Knoxville (original) (raw)

Papers by Arthur Ragauskas

Journal of Pulp and Paper Science

Nous avons examine la charge totale en fibres de pâte kraft de resineux du nord hautement blanchi... more Nous avons examine la charge totale en fibres de pâte kraft de resineux du nord hautement blanchie a une valeur finale de blancheur comparable de 88,0 %. Les resultats ont demontre que la charge totale en fibres de pâte decroissait d'une charge initiale de 95,9 mmol/g a une charge finale de 32,0 a 41,2 mmol/g a mesure que la pâte etait blanchie a une blancheur de ∼88 % selon les differentes sequences de blanchiment utilisees. Une deuxieme etape d'extraction alcaline (E 2 ) dans la sequence de blanchiment n'a pas fait augmenter la blancheur de facon notable mais a entraine une reduction de 10,9 a 15,0 % de la charge totale en fibres, qui a ete retenue lorsque nous avons elimine l'etape E 2 . En general, la charge totale en fibres de pâte des pâtes kraft de resineux du nord blanchies en utilisant les etapes DEDED, D(EPO)DED, et OQPZP a ete de 18,0 a 21,0% plus elevee que pour les pâtes blanchies selon (D+C)EDED, (D+C)(EO)DED, et OD(EPO)DD dans les conditions etudiees. Le peroxyde d'hydrogene pourrait etre employe pour accroitre la charge en fibres de 20,0 % s'il etait utilise a la derniere etape suivant un post-blanchiment au dioxyde de chlore OD(EPO)DP au lieu de OD(EPO)DD.

Holzforschung, 2000

Summary A series of laccase-mediator treatments (LMS) with 1-hydroxybenzotriazole (HBT) and N-ace... more Summary A series of laccase-mediator treatments (LMS) with 1-hydroxybenzotriazole (HBT) and N-acetyl-Nphenylhydroxylamine (NHAA) (Fig. 1) as the mediators were performed on a laboratory prepared southern softwood conventional kraft pulp (kappa # 75.4). Subsequent to the LMS treatments, the treated pulps were subjected to various oxidatively reinforced alkaline extraction stages (E*). The kappa results suggested that both LMSHBT and LMSNHAA treatments delignified this high-kappa pulp. The E* stages were beneficial in countering the darkening effect observed after the LMS treatments. Structural changes in residual lignins isolated before and after laccase-mediator (LMSNHAA (E*) and LMSHBT (E*)) treatments were explored. The spectral analysis of phosphitylated residual lignins revealed an increase in carboxylic acid content and a depletion of phenolic hydroxyl groups in non-condensed at C-5 lignin moieties. Aliphatic hydroxyl groups were substantially decreased when NHAA was used. Over...

evolves from the singular relationship between the Institute and the pulp and paper industry whic... more evolves from the singular relationship between the Institute and the pulp and paper industry which has existed since 1929. The purpose of the Institute is fulfilled through three missions, which are: · to provide high quality students with a multidisciplinary graduate educational experience which is of the highest standard of excellence recognized by the national academic community and which enables them to perform to their maximum potential in a society with a technological base; and · to sustain an international position of leadership in dynamic scientific research which is participated in by both students and faculty and which is focused on areas of significance to the pulp and paper industry; and · to contribute to the economic and technical well-being of the nation through innovative educational, informational, and technical services.

The Institute of Paper Science and Technology (IPST) has provided a high standard of professional... more The Institute of Paper Science and Technology (IPST) has provided a high standard of professional service and has put forth its best efforts within the time and funds available for this project. The information and conclusions are advisory and are intended only for internal use by any company who may receive this report. Each company must decide for itself the best approach to solving any problems it may have and how, or whether, this reported information should be considered in its approach. IPST does not recommend particular products, procedures, materials, or service. These are included only in the interest of completeness within a laboratory context and budgetary constraint. Actual products, procedures, materi-als, and services used may differ and are peculiar to the operations of each company. In no event shall IPST or its employees and agents have any obligation or liability for damages including, but not limited to, consequential damages arising out of or in connection with a...

The removal of lignin from wood is a key operation in the manufacturing of high-value paper produ... more The removal of lignin from wood is a key operation in the manufacturing of high-value paper products. Although most lignin is removed from wood during pulping, the last vestiges must be removed using a series of oxidation bleaching reactions. Historically, this was accomplished using hypochlorous acid or chlorine. _ Recently, environmental concerns have

The effectiveness of combinations of additives as brighmess stabilizers for hardwood and softwood... more The effectiveness of combinations of additives as brighmess stabilizers for hardwood and softwood BCTMP (bleached chemithermomechanical pulp) was examined. Certain additive combinations exhibit a synergistic interaction effect that provides a substantial brightness stabilization activity. Experimental results suggest that designing specific additive combinations is an effective approach to improve the brightness stability of mechanical pulps and to lower _e overall charge of additives.

The photo and thermal stabilizing effects of 2,2’-thiodiethanol (I), 2,2’dithiodiethanoI (2), and... more The photo and thermal stabilizing effects of 2,2’-thiodiethanol (I), 2,2’dithiodiethanoI (2), and 2,2’-oxydiethanethiol (3) were investigated for high brightness bleached chemithermomechanical pulps (BCTMP), The di-thiol additive 3 was shown to be the most effective photostabilizing reagent for freshly impregnated handsheets. Mechanistic studies suggest that di-thiol additives photostabilize BCTMP pulps no more effectively than mono-thiol additives. Long-term thermal reversion studies indicated that 2,2’-oxydiethanethiol also stabilized BCTMP handsheets against thermal yellowing. Photolysis of the aged handsheets indicated that the photostabilizing efficiency of additive 3 was detrimentally impacted upon by long term storage prior to photolysis.

Laboratory mechanical softwood pulps (MSP) and commercial bleached softwood kraft pulps (BSKP) we... more Laboratory mechanical softwood pulps (MSP) and commercial bleached softwood kraft pulps (BSKP) were mechanically fibrillated by stone grinding with a SuperMassColloider ®. The extent of fibrillation was evaluated by SEM imaging, water retention value (WRV) and cellulase adsorption. Both lignin content and mechanical treatment significantly affected deconstruction and enzymatic saccharification of fibrillated MSP and BSKP. Fibrillation of MSP and BSKP cell walls occurs rapidly and then levels off; This work is conducted on official government time of Zhu while Hoeger and Nair were visiting scientists at the USDA

Green Chem., 2015

Torrefaction has been shown to improve the chemical composition of bio-oils produced from fast py... more Torrefaction has been shown to improve the chemical composition of bio-oils produced from fast pyrolysis by lowering its oxygen content and enhancing the aromatic yield.

The synergistic interactions between xylanase pretreatment of kraft pulps and subsequent chemical... more The synergistic interactions between xylanase pretreatment of kraft pulps and subsequent chemical bleaching reactions were explored with dimethyldioxirane (DMD) and ozone. Laboratory studies indicated the biobleaching process was favorable for either hardwood or softwood kraft pulps. The pretreatment of kraft pulps with xylanase followed by (DMD)E(H 202/H2NCN) resulted in higher brightness values for the fully bleached pulp. Likewise, xylanase treatmems of an oxygen delignified, extended delignified kraft pulp enhanced the bleachability as determined using an OXZ(EO)D bleaching sequence. Imerestingly, although the xylanase stage in general reduced the viscosity of the pulps in comparison to control pulps, these differences in viscosity appeared to diminish during the bleaching process. These studies illustrate the important role that biobleaching processes have on improving the bleaching capabilities of oxygen-based bleaching sequences.

Oxygen bleachability of a low (kappa 26.6) and high (lappa 56.2) lignin content SW kraft pulp was... more Oxygen bleachability of a low (kappa 26.6) and high (lappa 56.2) lignin content SW kraft pulp was evaluated under conventional oxygen, extended 00, and @*)&:0.05@+0) conditions. The bleachability of the hgh kappa pulp was found to be superior to that of the low kappa pulp. At a constant charge of caustic, the relative percent deli@cation was found to be OO>O>(,E+O)Dw:o.os @+O) for the low and high kappa pulps. The mild conditions of the latter sequence yielded pulps with higher viscosity values. Hexenuronic acids conlributed 22% to the kappa number of the low lignin content brownstock and negligibly to the high lignin content brownstock. Changes in pulp bleachability of the high and low kappa S W kmft pulps were fkther investigated by isolating and characterizing the residual lignin of the pulps and the bleaching effluents. 13C NMR analysis of the kraft brownstock residual liindicated that the high kappa pulp had a greater amount of p0-aryl ethers and methoxyl groups in compar...

While many core pulping and bleaching technologies have been redefined over the past few decades,... more While many core pulping and bleaching technologies have been redefined over the past few decades, the future promises even greater change- from forest genetics, fibre modification and filler technologies which will significantly alter the primary furnish used for recycling. The author describes how the quality of recycled fibre has been affected by advances in kraft pulping - enhanced the strength and optical properties - and by the development of ECF and TCF pulps. The latter are now merging with the introduction of a D/Z or Z/D stage which reduces bleaching costs and improves strength properties. The challenge is to avoid the harmful changes which occur in the fibre structure during the pulping bleaching and refining operations. For this, new tools are emerging - genetic fibre modifications, enzymatic microchemistry and micro mechanical modification. Out-of-the-box thinking is needed to develop new sheet structures with significantly more filler- with filler which is engineered to...

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 D E D E D 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 1 3 C-NMR. I N T R O D U C T I O N Pulps that have been oxygen delignified to an extent of 5 0 % or less generally exhibit a tear factor at a given tensile strength that is similar to that of conventionally bleached pulps, despite having a lower viscosity [ 1 ] . However, it is well established that intensive oxygen delignification, e.g., two-stage oxygen treatment prior to nonch...

Polylactic acids polymer (PLA) was applied as an additive to improve the strength properties of h... more Polylactic acids polymer (PLA) was applied as an additive to improve the strength properties of handsheets prepared from three unbleached southern pine kraft pulps with different kappa number and an aspen bleached chemithermomechanical pulp (BCTMP). The results showed that PLA could greatly improve the tensile and burst strength of the pulp handsheets. Heat pressing effect was also important to enhance the strength properties. For unbleached kraft pulps, it was found that an appropriate amount of residual lignin in pulps had a positive effect on the handsheets strength improvement when adding PLA. The thickness of the handsheet did not change the PLA strengthening effect. In general, PLA effect on tear strength improvement could be neglected. However, it had a significant effect on the improvement of tear strength for the aspen BCTMP handsheets not containing sufficient amount of fines.

ACS Symposium Series

Page 1. Chapter 20 Laccase: A Harbinger to Kraft Pulping TJ Dyer and AJ Ragauskas Institute of Pa... more Page 1. Chapter 20 Laccase: A Harbinger to Kraft Pulping TJ Dyer and AJ Ragauskas Institute of Paper Science and Technology, Georgia Institute of Technology, 500 10th Street NW, Atlanta GA 30332 Southern pine wood chips ...

TAPPI Journal

This study involves an investigation of the impact of the various levels of atmospheric dielectri... more This study involves an investigation of the impact of the various levels of atmospheric dielectricbarrier discharge (DBD) treatment on the surface of eucalyptus fibers at different levels of beating with the objective of enhancing paper strength properties. The DBD treatment led to significant improvements in wet-strength tensile properties, increasing them by 2%-112%, as a function of the dosage of atmospheric plasma applied. Also, using controlled dosages of the DBD treatment, dry-strength tensile could be improved, reaching a 58% increase. In addition, non-beaten samples showed greater increases in strength properties than the beaten samples. Moreover, the acid surface content was unaltered by the DBD treatment, perhaps due to over-oxidation and generation of low molecular weight species that are easily removed by washing with water. Furthermore, increases in wettability could be observed for specific DBD dosage of treatments. Atomic force microscopy images of the treated handshe...

Journal of Pulp and Paper Science

Nous avons examine la charge totale en fibres de pâte kraft de resineux du nord hautement blanchi... more Nous avons examine la charge totale en fibres de pâte kraft de resineux du nord hautement blanchie a une valeur finale de blancheur comparable de 88,0 %. Les resultats ont demontre que la charge totale en fibres de pâte decroissait d'une charge initiale de 95,9 mmol/g a une charge finale de 32,0 a 41,2 mmol/g a mesure que la pâte etait blanchie a une blancheur de ∼88 % selon les differentes sequences de blanchiment utilisees. Une deuxieme etape d'extraction alcaline (E 2 ) dans la sequence de blanchiment n'a pas fait augmenter la blancheur de facon notable mais a entraine une reduction de 10,9 a 15,0 % de la charge totale en fibres, qui a ete retenue lorsque nous avons elimine l'etape E 2 . En general, la charge totale en fibres de pâte des pâtes kraft de resineux du nord blanchies en utilisant les etapes DEDED, D(EPO)DED, et OQPZP a ete de 18,0 a 21,0% plus elevee que pour les pâtes blanchies selon (D+C)EDED, (D+C)(EO)DED, et OD(EPO)DD dans les conditions etudiees. Le peroxyde d'hydrogene pourrait etre employe pour accroitre la charge en fibres de 20,0 % s'il etait utilise a la derniere etape suivant un post-blanchiment au dioxyde de chlore OD(EPO)DP au lieu de OD(EPO)DD.

Holzforschung, 2000

Summary A series of laccase-mediator treatments (LMS) with 1-hydroxybenzotriazole (HBT) and N-ace... more Summary A series of laccase-mediator treatments (LMS) with 1-hydroxybenzotriazole (HBT) and N-acetyl-Nphenylhydroxylamine (NHAA) (Fig. 1) as the mediators were performed on a laboratory prepared southern softwood conventional kraft pulp (kappa # 75.4). Subsequent to the LMS treatments, the treated pulps were subjected to various oxidatively reinforced alkaline extraction stages (E*). The kappa results suggested that both LMSHBT and LMSNHAA treatments delignified this high-kappa pulp. The E* stages were beneficial in countering the darkening effect observed after the LMS treatments. Structural changes in residual lignins isolated before and after laccase-mediator (LMSNHAA (E*) and LMSHBT (E*)) treatments were explored. The spectral analysis of phosphitylated residual lignins revealed an increase in carboxylic acid content and a depletion of phenolic hydroxyl groups in non-condensed at C-5 lignin moieties. Aliphatic hydroxyl groups were substantially decreased when NHAA was used. Over...

evolves from the singular relationship between the Institute and the pulp and paper industry whic... more evolves from the singular relationship between the Institute and the pulp and paper industry which has existed since 1929. The purpose of the Institute is fulfilled through three missions, which are: · to provide high quality students with a multidisciplinary graduate educational experience which is of the highest standard of excellence recognized by the national academic community and which enables them to perform to their maximum potential in a society with a technological base; and · to sustain an international position of leadership in dynamic scientific research which is participated in by both students and faculty and which is focused on areas of significance to the pulp and paper industry; and · to contribute to the economic and technical well-being of the nation through innovative educational, informational, and technical services.

The Institute of Paper Science and Technology (IPST) has provided a high standard of professional... more The Institute of Paper Science and Technology (IPST) has provided a high standard of professional service and has put forth its best efforts within the time and funds available for this project. The information and conclusions are advisory and are intended only for internal use by any company who may receive this report. Each company must decide for itself the best approach to solving any problems it may have and how, or whether, this reported information should be considered in its approach. IPST does not recommend particular products, procedures, materials, or service. These are included only in the interest of completeness within a laboratory context and budgetary constraint. Actual products, procedures, materi-als, and services used may differ and are peculiar to the operations of each company. In no event shall IPST or its employees and agents have any obligation or liability for damages including, but not limited to, consequential damages arising out of or in connection with a...

The removal of lignin from wood is a key operation in the manufacturing of high-value paper produ... more The removal of lignin from wood is a key operation in the manufacturing of high-value paper products. Although most lignin is removed from wood during pulping, the last vestiges must be removed using a series of oxidation bleaching reactions. Historically, this was accomplished using hypochlorous acid or chlorine. _ Recently, environmental concerns have

The effectiveness of combinations of additives as brighmess stabilizers for hardwood and softwood... more The effectiveness of combinations of additives as brighmess stabilizers for hardwood and softwood BCTMP (bleached chemithermomechanical pulp) was examined. Certain additive combinations exhibit a synergistic interaction effect that provides a substantial brightness stabilization activity. Experimental results suggest that designing specific additive combinations is an effective approach to improve the brightness stability of mechanical pulps and to lower _e overall charge of additives.

The photo and thermal stabilizing effects of 2,2’-thiodiethanol (I), 2,2’dithiodiethanoI (2), and... more The photo and thermal stabilizing effects of 2,2’-thiodiethanol (I), 2,2’dithiodiethanoI (2), and 2,2’-oxydiethanethiol (3) were investigated for high brightness bleached chemithermomechanical pulps (BCTMP), The di-thiol additive 3 was shown to be the most effective photostabilizing reagent for freshly impregnated handsheets. Mechanistic studies suggest that di-thiol additives photostabilize BCTMP pulps no more effectively than mono-thiol additives. Long-term thermal reversion studies indicated that 2,2’-oxydiethanethiol also stabilized BCTMP handsheets against thermal yellowing. Photolysis of the aged handsheets indicated that the photostabilizing efficiency of additive 3 was detrimentally impacted upon by long term storage prior to photolysis.

Laboratory mechanical softwood pulps (MSP) and commercial bleached softwood kraft pulps (BSKP) we... more Laboratory mechanical softwood pulps (MSP) and commercial bleached softwood kraft pulps (BSKP) were mechanically fibrillated by stone grinding with a SuperMassColloider ®. The extent of fibrillation was evaluated by SEM imaging, water retention value (WRV) and cellulase adsorption. Both lignin content and mechanical treatment significantly affected deconstruction and enzymatic saccharification of fibrillated MSP and BSKP. Fibrillation of MSP and BSKP cell walls occurs rapidly and then levels off; This work is conducted on official government time of Zhu while Hoeger and Nair were visiting scientists at the USDA

Green Chem., 2015

Torrefaction has been shown to improve the chemical composition of bio-oils produced from fast py... more Torrefaction has been shown to improve the chemical composition of bio-oils produced from fast pyrolysis by lowering its oxygen content and enhancing the aromatic yield.

The synergistic interactions between xylanase pretreatment of kraft pulps and subsequent chemical... more The synergistic interactions between xylanase pretreatment of kraft pulps and subsequent chemical bleaching reactions were explored with dimethyldioxirane (DMD) and ozone. Laboratory studies indicated the biobleaching process was favorable for either hardwood or softwood kraft pulps. The pretreatment of kraft pulps with xylanase followed by (DMD)E(H 202/H2NCN) resulted in higher brightness values for the fully bleached pulp. Likewise, xylanase treatmems of an oxygen delignified, extended delignified kraft pulp enhanced the bleachability as determined using an OXZ(EO)D bleaching sequence. Imerestingly, although the xylanase stage in general reduced the viscosity of the pulps in comparison to control pulps, these differences in viscosity appeared to diminish during the bleaching process. These studies illustrate the important role that biobleaching processes have on improving the bleaching capabilities of oxygen-based bleaching sequences.

Oxygen bleachability of a low (kappa 26.6) and high (lappa 56.2) lignin content SW kraft pulp was... more Oxygen bleachability of a low (kappa 26.6) and high (lappa 56.2) lignin content SW kraft pulp was evaluated under conventional oxygen, extended 00, and @*)&:0.05@+0) conditions. The bleachability of the hgh kappa pulp was found to be superior to that of the low kappa pulp. At a constant charge of caustic, the relative percent deli@cation was found to be OO>O>(,E+O)Dw:o.os @+O) for the low and high kappa pulps. The mild conditions of the latter sequence yielded pulps with higher viscosity values. Hexenuronic acids conlributed 22% to the kappa number of the low lignin content brownstock and negligibly to the high lignin content brownstock. Changes in pulp bleachability of the high and low kappa S W kmft pulps were fkther investigated by isolating and characterizing the residual lignin of the pulps and the bleaching effluents. 13C NMR analysis of the kraft brownstock residual liindicated that the high kappa pulp had a greater amount of p0-aryl ethers and methoxyl groups in compar...

While many core pulping and bleaching technologies have been redefined over the past few decades,... more While many core pulping and bleaching technologies have been redefined over the past few decades, the future promises even greater change- from forest genetics, fibre modification and filler technologies which will significantly alter the primary furnish used for recycling. The author describes how the quality of recycled fibre has been affected by advances in kraft pulping - enhanced the strength and optical properties - and by the development of ECF and TCF pulps. The latter are now merging with the introduction of a D/Z or Z/D stage which reduces bleaching costs and improves strength properties. The challenge is to avoid the harmful changes which occur in the fibre structure during the pulping bleaching and refining operations. For this, new tools are emerging - genetic fibre modifications, enzymatic microchemistry and micro mechanical modification. Out-of-the-box thinking is needed to develop new sheet structures with significantly more filler- with filler which is engineered to...

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 D E D E D 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 1 3 C-NMR. I N T R O D U C T I O N Pulps that have been oxygen delignified to an extent of 5 0 % or less generally exhibit a tear factor at a given tensile strength that is similar to that of conventionally bleached pulps, despite having a lower viscosity [ 1 ] . However, it is well established that intensive oxygen delignification, e.g., two-stage oxygen treatment prior to nonch...

Polylactic acids polymer (PLA) was applied as an additive to improve the strength properties of h... more Polylactic acids polymer (PLA) was applied as an additive to improve the strength properties of handsheets prepared from three unbleached southern pine kraft pulps with different kappa number and an aspen bleached chemithermomechanical pulp (BCTMP). The results showed that PLA could greatly improve the tensile and burst strength of the pulp handsheets. Heat pressing effect was also important to enhance the strength properties. For unbleached kraft pulps, it was found that an appropriate amount of residual lignin in pulps had a positive effect on the handsheets strength improvement when adding PLA. The thickness of the handsheet did not change the PLA strengthening effect. In general, PLA effect on tear strength improvement could be neglected. However, it had a significant effect on the improvement of tear strength for the aspen BCTMP handsheets not containing sufficient amount of fines.

ACS Symposium Series

Page 1. Chapter 20 Laccase: A Harbinger to Kraft Pulping TJ Dyer and AJ Ragauskas Institute of Pa... more Page 1. Chapter 20 Laccase: A Harbinger to Kraft Pulping TJ Dyer and AJ Ragauskas Institute of Paper Science and Technology, Georgia Institute of Technology, 500 10th Street NW, Atlanta GA 30332 Southern pine wood chips ...

TAPPI Journal

This study involves an investigation of the impact of the various levels of atmospheric dielectri... more This study involves an investigation of the impact of the various levels of atmospheric dielectricbarrier discharge (DBD) treatment on the surface of eucalyptus fibers at different levels of beating with the objective of enhancing paper strength properties. The DBD treatment led to significant improvements in wet-strength tensile properties, increasing them by 2%-112%, as a function of the dosage of atmospheric plasma applied. Also, using controlled dosages of the DBD treatment, dry-strength tensile could be improved, reaching a 58% increase. In addition, non-beaten samples showed greater increases in strength properties than the beaten samples. Moreover, the acid surface content was unaltered by the DBD treatment, perhaps due to over-oxidation and generation of low molecular weight species that are easily removed by washing with water. Furthermore, increases in wettability could be observed for specific DBD dosage of treatments. Atomic force microscopy images of the treated handshe...