LMS BiobleachingProcess Parameter StudiesProcess Parameter Studies

Art J RagauskasArt J. Ragauskas

Institute of Paper Science and Technology

Pulp Bleaching• Purpose of bleaching is 2-fold:

– to remove the residual lignin– to brighten the pulp

• Current bleaching technologies• Current bleaching technologies consist of:– O2, ClO2, H2O2, & O3– Capital intensive– Limited selectivity

D has environmental limitations– D has environmental limitations

– New bleaching agents needed!

LACCASE-MEDIATEDBIOBLEACHINGBIOBLEACHING

Laccase: Overview

LaccaseOH

Cu1+

HisN

Cu1+

NHis

1+Cu

Type II

Type IIIHO

H

Cu2+

Cu2+

HisN O NHis

2+Cu

O2

SCys

Cu1+

Type I

SCys

Cu2+

H

Oxidoreductase enzyme E.I. Solomon et al

Fully Reduced Fully Oxidized

•y

Reduces O2 to H2O2concomitantly oxidizesconcomitantly oxidizes

• MW varies 65 000 140 000

•Catalysis occurs due to 4 copper atoms/active site

• MW varies 65,000-140,000.• Carbohydrate content ~10-45 (% wt). • Active sites near surface

Active sites on surface

Laccase: Overview• Proposed to be involved in lignin biosynthesis• Oxidize a wide array of phenolic substrates• Oxidize a wide array of phenolic substrates

HOOR

OCH3HO

HO OOCH3

MeOOH

OH

OCH3

OR2

OCH3H3CO

OO

OCH3

Laccase/O2

OH

MeO OMeHO

OMe

OMe

OHOH

CO2H

H3CO

OH

OCH3H3CO

OHHi hi W d S i T h 24 22(1990)Higuchi, Wood Sci. Techn., 24, 22(1990)

Laccase BiobleachingPulp Fiber

O22

Low MW Co-factor - Mediator

Laccase Biobleaching

LMS-Process

g

O LACCASE MEDIATOR LIGNINO2 LACCASE MEDIATOROX LIGNIN

H2O LACCASEOXMEDIATOR LIGNINOXOX

Laccase BiobleachingC di i LMS(E)

Laccase Lac/ABTS Lac/HBTLac/NHA Lac/VA

Conditions LMS(E)

• LMS: 45oC, 1-2 h, 5-20% csc, pH 4 6 1 4% mediator +40 psi

50

60

pH 4 - 6, 1-4% mediator, +40 psi

• E: 70oC, 1-3 h, 1-2% NaOH

30

40

50

elig

nific

atin

H4NO3S

N

SN N

N

SSO3NH4

ABTS

0

10

20

% D

e

S f fN

N

NOO

OH

N OHO

SW Kraft HW Kraft

Highly selective for lignin, little degradation of pulp carbohydrates

NN

OHHN NH

O HBT VA NHA Call -1995 Amman 1997

degradation of pulp carbohydratesRagauskas et al: Enzyme and Micro. Technol., 23, 422 (1998), TAPPI J., 83(9), 66(2000);

J. Wood Chem. Technol., 20(2), 169(2000)

LMSVA Biobleaching High/Low Kappa Kraft P lpsKraft Pulps

Conditions45

50

LMS

5.4 x 105 U laccase/gr od pulp

45oC 2h 120 psi O 9% csc30

35

40

45

45oC, 2h, 120 psi O2, 9% csc, med.= VA

EP15

20

25

30

Kapp

a #

80oC, 1.5 h, 0.5% H2O2,

10% csc

0

5

10

15

0

SW1

SW1-LMS(EP)

SW2

SW2-LMS(EP)

HW1

HW1-LMS(EP)HW2

HW2-LMS(EP)

LMS applicable to low and hi h k k ft lhigh kappa kraft pulps

LMSVA Biobleaching: Lignin Reactivity

1 2

Start LMS(EP)mmol/g lignin

0 8

1

1.2

O MeOMe

OH

0.4

0.6

0.8 O H

0

0.2

SW(50 0 K) SW(27 5 K) SW(50 0 K) SW(27 5 K)SW(50.0 K) SW(27.5 K) SW(50.0 K) SW(27.5 K)

LMS ti it i il i h li i ll C5 d d i SWLMS reactivity primarily via phenolics, especially C5 noncondensed in SWDelving into the Fundamental LMS Delignification of High-Kappa Pulps.

Biotechnology in the Pulp and Paper Industry, 151-164 (2002).

Biobleaching High and Low Kappa PulpsBiobleaching High and Low Kappa Pulps

Pulp % Delign. % Yield

SW kappa 50 43 99.9

SW kappa 28 62 100.0

HW kappa 27 65a 98.6pp

HW kappa 11 70a 99.1

ak i il h i idakappa primarily hexenuronic acids

Yield Kappa Relationships

50

48

50

d, %

LMS(E*)50(LMS)E*DED

44

46

n W

ood

Pulping50(OO)

50(OO)DED

( )

40

42

Yiel

d on

30DED

38

40Y

30ODED

0 10 20 30 40 50 60Kappa Number

LMSVA Bleaching Sequence StudiesLMSVA Bleaching Sequence Studies• LMS based sequences e l t ECF i fi l90 equal to ECF in final brightness properties

• LMS yield gains occur from higher selectivity for

50607080

right

ness

from higher selectivity for high kappa pulps

• What is not yet established:

10203040

TAPP

I Br

established:

• NPE effects

• Mixing effects

0

Browns

tock

MS(LMS)(E

PO)

LMS)(E

PO)DE

PO)DED(0.

6%)

PO)DED(0.

8%)

PO)DED(1.

0%)

Browns

tock

OOOOD(E

PO)

(EPO)D

(0.4%)

(EPO)D

(0.6%)

(EPO)D

(0.8%)

• Carryover effectsLMS

LMS(LM

LMS(LM

S)(EPO

LMS(LM

S)(EPO

LMS(LM

S)(EPO

OOD(EOOD(EOOD(E

NPE’s on LMSNPE s on LMS• Most LMS studies have been

preformed using ‘clean systems’• All kraft pulps and process

streams have nonprocesss elements present (Ca Mg Fe Mnelements present (Ca, Mg, Fe, Mn, Cu, Ni, etc)

Exp DesignExp. Design• Perform LMS(E) and repeat with

NPEs • Compare delignification and

viscosity properties of biobleached lpulps

LMSVA Bleaching: Effects of NPEs

55

60

VA g

40

45

50

pa #

30

35

40

Kap

p

20

25

BS

S(E)

l(E)

l(E)

(E)

4(E)

4(E)

4(E)

4(E)

B

LMS(

LMS-

0.1%NaC

l(LM

S-1.0

%NaCl(

LMS-

1% M

NSO4(E

LMS-

1%NiSO

4(ELM

S-1%

FeSO

4(ELM

S-1%

CuSO4(

LMS-

1%MgS

O4(

>> no observed NPE impact on delignification

LMSVA Bleaching: Effects of NPEs55

60VA g

40

45

50

osity

/cP

30

35Visc

o

`

20

25

BS

LMS(E)

NaCl(E

)

NaCl(E

)

SO4(E

)

SO4(E

)

SO4(E

)

SO4(E

)

SO4(E

)

LMLMS-0.

1%NaC

LMS-1.0%

NaCLMS-1%

MnS

OLMS-1%

NiSOLMS-1%

FeSO

LMS-1%CuS

OLMS-1%

MgS

O

>> slight NPE impact on pulp viscosity

LMSVA Bleaching: Effect of MixingLMSVA Bleaching: Effect of Mixing

bj iObjective

Assess the impact of mixing on an LMS stage

Experimental Procedure

Biobleaching Sequence LMS(EPO)

-LMS:Lac: 1.4 x 107 U/10 gr pulp, 45 min., 4.5 pH, 4% VA, 120 psi O2LMS:Lac: 1.4 x 10 U/10 gr pulp, 45 min., 4.5 pH, 4% VA, 120 psi O2

Quantum reactor, 10% csc, 55oC,

-(E+P+O): 70oC, 1 h, 10% csc, 60 psi, 0.5% H2O2, 2.5% NaOH( ) , , , p , 2 2,

LMSVA Bleaching: Effect of Mixing

LMS Mixing Conditions: Quantum g Q

A. 600 rpm for 10 sec every 2 min.

B 1200 rpm for 5 sec every 2 minB. 1200 rpm for 5 sec every 2 min.

C. 2400 rpm for 2.5 sec every 2 min. [constant refining energy]

Pulp Kappa # Viscosity/cP TAPPI Brightness

Brownstock 33.3 30.4 25.9

A(E+P+O) 14.6 23.6 34.2

B(E+P+O) 14.4 23.2 34.2

C(E+P+O) 14.3 23.1 33.3

LMSVA Bleaching: Effect of Mixing

i i di i

VA g g

LMS Mixing Conditions:

D. 600 rpm for 10 sec every 2 min.

E. 3600 rpm for 10 sec every 2 min. [variable mixing energy]

P l K # Vi it / P TAPPI B i htPulp Kappa # Viscosity/cP TAPPI Brightness

Brownstock 33.3 30.4 25.9

D(E+P+O) 14.2 23.8 32.9

E(E+P+O) 14.0 22.7 32.6

LMSVA Bleaching: Effect of MixingLMS Mixing Conditions:

F 600 rpm for 10 sec every 2 min – 20% csc (Quantum)F. 600 rpm for 10 sec every 2 min. – 20% csc (Quantum)

G. 2400 rpm for 10 sec every 2 min. – 20% csc (Quantum)

H 48 10% (P ddl i )H. ≈48 rpm- constant – 10% csc (Parr reactor, paddle mixer)

Pulp Kappa # Viscosity/cP

Brownstock 33.3 30.4

F(E+P+O) 14 2 22 9F(E+P+O) 14.2 22.9

G(E+P+O) 14.1 23.6

H(E+P+O) 16 3H(E+P+O) 16.3 --Provide efficient mixing is occurring in a LMS-stage, detrimental shear effects were not observed

Black Liquor Carryover on LMSq y• Most LMS studies have been

preformed using ‘clean systems’• All kraft pulps are delignified in the

presence of black liquor carryover and this is know to influence O D and Pthis is know to influence O, D and P.

• Effect on LMS is unknownExp DesignExp. Design• Perform LMS(E) with and without

Black liquor carryover • Compare delignification and viscosity

properties of biobleached pulps

LMSVA Bleaching: Effect of Carryover

50

40

#

30

Kap

pa

20BS 0% Solids 0.1% Solids 0.5% Solids 1.0% Solids 5.0% Solids

% Solids carryover added

2% charge of VA in LMSVA

LMSVA Bleaching: Effect of CarryoverLMSVA Bleaching: Effect of Carryover50

4% VA

40

20

30

Kap

pa #

10

0Brownstock 1%

Carryover5%

Carryover10%

Carryover20%

Carryover30%

Carryover

Carryover levels of 10% black liquor solids are not detrimental towards an LMS stage

LMS - BIOBLEACHINGLMS BIOBLEACHING

Effect of Temperature – pH on LMS

LMSVA Bleaching: Effect of TemperatureVA g p50

40#

30

Kap

pa

30

20BS [LMS-

45](E)[LMS-55](E)

[LMS-65](E)

[LMS-75](E)

[LMS-85](E)

[LMS-95](E)

Temperature limitations of laccase employed limited LMS stage to ∼20–75oC

LMSVA Bleaching: Effect of pH

45

50

35

40

pa #

30

35

Kap

p

20

25

S E) E) E) E) E) E) E) E) E)BS

[LMS-2.9](

E)

[LMS-4.7](E

)

[LMS-5.1](E

)

[LMS-5.3](E

)

[LMS-6.4](E

)

[LMS-6.9](E

)

[LMS-7.0](E

)

[LMS-7.1](E

)

[LMS-8.9](E

)

pH limitations of laccase employed limit LMS stage to ∼ 3 - 5

Laccase Biobleaching: Conclusions/FutureLaccase Biobleaching: Conclusions/Future• LMS biodelignification of high kappa pulps is possible and provides distinct yield benefits• LMS delignified pulps can be bleached to high brightness

lvalues• NPEs have minimal impact on LMS stage• LMS is not sensitive to shear effectsLMS is not sensitive to shear effects• LMS is not detrimentally impacted by moderate levels of black liquor carryoverq y

• pH/temperature profiles of LMS need to be improvedC i di LMS di d b i d• Cost issues surrounding LMS mediator need to be improved

AcknowledgementsAcknowledgements

U.S. Department of Energy

Member Companies of IPST