ISBN : 978-602-17761-4-8
38
Proceedings of 2
nd
REPTech Crowne Plaza Hotel, Bandung, November 15-17, 2016
© 2016 Published by Center for Pulp and Paper through 2
nd
REPTech
Actual deligniication intensity Li ≈ [ H ΔL ] [Y 100 ] ------------------------------------ II where:
• H = calculated H-factor refer to Equation I; ΔL = residual lignin content in unscreened pulp; Y = total unscreened pulp yield ; the obtained actual deligniication intensity Li was
further transformed into
e
logarithmic ln; e = 2.71828 or in other words went through the ln transformation Figure 2a; Appendix A
3.2.3. The Forming of Kraft Pulp Sheet
Kraft screened-pulp yield that reached the highest over particular H factor was selected and further formed into handsheet without beating. Afterwards, the pulpsheets were conditioned for about 24 hours
and then tested for their physical-strength properties also in accodance with the TAPPI standards [9].
4. Results and Discussion 4.1. Wood Basic Properties
The examined wood properties covered basic density, lignin content, and ratio of syringil-to-vanillin lignin monomers Table 1. There was strong indication that those properties differed among the four
FP wood species Table 1: Basic properties of four tropical plantation-forest wood species [8]
1
No Wood species
Basic density gramcm
3
Lignin content SyrngilVanillin
ratio 1
Sengon Paraserianthes falcataria L Nielsen
0.45 26.72
2.03 2
Gmelina Gmelina arborea Roxb 0.48
25.50 2.02
3 Meranti kuning Shorea spp.
0.57 24.89
1.87 4
Kapur Dryobalanops spp. 0.62
26.40 1.30
F-test for signiicant difference
Remarks:
1
Average of 5 replications; = signiicant at P = 0.05; = signiicant at P = 0.01
4.2. The Obtained H-factors
The H-factor values as obtained are presented in Table 2. Greater H-factor values i.e. theoretical deligniication intensity implied the more severe intense kraft coking condition; and vice versa.
Table 2. H-factors as obtained by manipulating cooking duration and temperature as single variable [5,8]
T max
o
C t
Tr à Tm
minutes t
TM
minutes T
Tot
minutes H-factors
170 90.00
0.00 90.00
117.88 170
90.00 30.00
120.00 579.34
170 90.00
60.00 150.00
1040.81 170
90.00 90.00
180.00 1502.25
175 93.15
0.00 93.15
173.87 175
93.15 30.00
123.15 866.56
175 93.15
60.00 153.15
1559.25 175
93.15 90.00
183.15 2182.67
Remarks: T max = maximum cooking temperature; t
Tr à Tm
= the duration that took from the room temperature raising to maximum cooking temperature; t
TM
= the duration at maximum cooking temperature; t
Tot
= total duration of t
Tr à Tm
+ t
TM;
Calculated using Vroom formula refer to Equation I
ISBN : 978-602-17761-4-8
39
Proceedings of 2
nd
REPTech Crowne Plaza Hotel, Bandung, November 15-17, 2016
© 2016 Published by Center for Pulp and Paper through 2
nd
REPTech
4.3. Properties of Kraft Pulping
Data on pulping properties varied with wood species as well as H-factors Appendix A. Greater H-factors clearly induced actual deligniication intensity Figure 2a, causing more intensive dissolution
of lignin. This was implied by the decrease of total unscreened pulp yield Figure 2b. More intensive lignin dissolution also rendered iber separation more perfect, thereby increasing screened-pulp yield
to some extent Figure 2c and concurrently decreasing pulp reject Figure 2d. Beyond H-factor at 1502.25, overall screened-pulp yield from four PF wood species apparently tended to decrease
Figure 2c. Presumably besides more intensive iber separation, such was caused by more severe wood carbohydrate degradation esp. cellulose and hemicellulose with more severe cooking-condition
H-factor 1502.25. As described before, H-factor served just as theoretical deligniication intensity, regardless of e.g.
different cooked-wood species. Should the H-factor values be linked to the actual deligniication intensity, there appeared a difference in such intensity among PF wood species at particular H-factors,
whereby highest actual deligniication intensity occurred to gmelina wood, followed in decreasing order by sengon, meranti kuning, and kapur Figure 2a. This indicated that lignin removal dissolution
at the irst two species proceeded easier than the latest two species. It is interesting that the irst two species exhibited greater ratio of syringil-to-vanillin SV units, while the latest two species revealed
the lower ratio Table 1. This also implied that the active-selective actual kraft deligniication intensity seemed affected by ratio of SV units correlation coeff: R
2
=0.2026; R=+0.4501 Figure 3a. However, wood density also correlated with such active-selective actual kraft deligniication intensity,
but less strongly R
2
=0.2005; R=-0.4478 Figure 3b; while wood initial lignin content did so, yet insignicantly R
2
=0.0688
tn
; R=+0.2623
tn
Figure 3c. In all this suggested that SV ratio affected the active-selective actual deligniication intensity the strongest, followed in decreasing order by wood
density and initial lignin content. Further, the active selective deligniication correlated positively with screen-pulp yield R=+0.3529 Figure 4a and negatively with pulp rejects R=-0.7739 Figure
4b. This was explicable, as such active-selective action induced more lignin dissolution and lessened carbohydrate degradation, thereby intensifying iber-to-iber separation
45 50
55 60
65
100 400
700 1000
1300 1600
1900 2200
H-factor
T o
ta l
p ul
p y
ie ld
,
Sengon Gmelina
Meranti kuning Kapur
B
3 4
5 6
7 8
100 400
700 1000
1300 1600
1900 2200
H-factor D
e li
g ni
fi c
a ti
o n
in te
n s
it y
ln t
ra n
s fo
rm a
ti o
n
Sengon Gmelina
Meranti kuning Kapur
A
35 37
39 41
43 45
47 49
51 53
55
100 400
700 1000
1300 1600
1900 2200
H-factor S
c reened-
pul p
y iel
d,
Sengon Gmelina
Meranti kuning Kapur
C 5
10 15
20 25
100 400
700 1000
1300 1600
1900 2200
H-factor P
u lp
r e
je c
t,
Sengon Gmelina
Meranti kuning Kapur
D
Figure 2. Relationship of H-factor consecutively with deligniication intensity A, with total unscreened pulp yield B, with screened-pulp yield C, and with pulp reject D [8]
ISBN : 978-602-17761-4-8
40
Proceedings of 2
nd
REPTech Crowne Plaza Hotel, Bandung, November 15-17, 2016
© 2016 Published by Center for Pulp and Paper through 2
nd
REPTech
3 4
5 6
7 8
0,4 0,45
0,5 0,55
0,6 0,65
Wood basic density, gcm
3
D e
li g
ni fi
c a
ti o
n in
te n
s it
y L
n. tr