全 文 ：№.6　　　　　　　　　　　　　　　 　　　　陕西科技大学学报　　　　　　　　　　　　　　　　　　Dec.2010
Vol.28 　　　　　　JOURNAL OF SH AANXI UNIVERSIT Y OF SCIENCE &T ECHNOLOGY　　　　　　·7·
＊　文章编号:1000-5811(2010)06-0007-06
EFFECTOF LIPASE TREATMENTON THE BLEACHABILITY
OF BAMBUSA CHUNGII SCMP
LI Bing-yun , ZHAN Huai-yu , WANG Shuang-fei , QIN Cheng-rong , FU Shi-yu1
(1.State Key Lab of Pulp and Pape rmaking , South China Univ ersity of Technolog y , Guang zhou 51060 , Chi-
na;2.Co llege of Light Industry and Food Enginee ring , Guangx i Univ ersity , Nanning 530004 , China)
Abstract:In o rder to improve the bleachabi li ty , Bambusa chungii SCMP was pret reated wi th
lipase.T he inf luence of treating variables of the lipase pret reatment on the hydro gen pero x-
ide bleaching of Bambusa chungi i SCMP was studied.The properties of SCMP fiber surface
w as also investigated by X-ray photoelect ron spectro scopy(XPS)and atomic force microsco-
py(AFM).The results indicated that enzymat ic pret reatment could improve the hydrogen
pero xide bleachability and brightness stabi li ty by removing ex t ractiv es on fiber surface.The
optimal conditions w ere as follow s:lipase do sage of 10 IU/g , pH of 8 , temperature of
35 ℃, pulp consistency of 10% and time o f 30 m in.From the analy sis of fiber surface of
pulps by XPS and AFM , it w as found that 57.45% and 7.57%o f total fiber surface o f Bam-
busa chungi i SCMP were covered w ith lignin and ex t ractives , respectively.And lipase t reat-
ment could remove considerable ex t ractives f rom the surface of SCMP fiber and more lignin
w ould be expo sed on the fiber surfac , which is favorable fo r the improvement of pulp bleach-
ability .
Key words:lipase;hydrogen peroxide bleaching;Bambusa chungii SCMP ;X-ray photoelec-
t ron spect ro scopy;atomic force micro scopy
CLC Number:TS745　　　　Document Code:A
0　Introduction
In the last decade , with the increasing product ion of pulp and paper and limitation of w ood materials
used for making pulp , the production of mechanical and chemimechanical pulp rapidly increased in Chi-
na.But due to most of lignin and ex tractives re tained on the fibe r surface o f chemimechanical pulp[ 1] ,
there are some disadvantages of chemimechanical pulp , such as dif ficulty in bleaching and poor stability
of it s brightness , which limit it s applicat ion to high g rade paper products.Trig lyceride is one of the im-
po rtant consti tuents of w ood ex t ractives that cover most o f the surface w ith lignin and can be dissolved
in white w ater to fo rm dissolved and co lloidal substances(DCS)[ 2] .Lipase has been used to hydrolyze
t rig lycerides released f rom mechanical pulping , re sulting in a decrease o f t riglycerides content on the
surface and an increase in f ree fat ty acids in the pulp fil trate
[ 3] .Lipase treatment could also decrease the
surface coverage of ex tractives on chemimechanical pulp[ 4] .The surface chemical proper ties o f mechani-
cal pulps have been studied w ith surface-sensitive analy sis techniques , such as atomic force microscopy
(AFM)and X-ray pho toelectron spect roscopy(XPS)[ 5 , 6] .XPS provides info rmation about the elements
on the surface and thei r bonding down to a depth o f 5 ～ 10 nm.XPS is considered as a quant ita tive o r at
least semi-quanti tat ive surface analy sis method.
＊ 收稿日期:2010-10-08
作者简介:李兵云(1975-),男 ,山东省东营市人,讲师 ,在读博士生 ,研究方向:酶法制浆 、漂白及生物应用
基金项目:国家 973预研项目(2006CB70861.4)
陕西科技大学学报 第 28 卷
In the present w ork , Bambusa chungii SCMP was t reated wi th lipase.The operat ing variables o f
enzymatic treatment , such as lipase do sage , temperature , pH value and time , were examined.A nd the
ef fect of lipase on the surface chemist ry of SCMP was studied w ith a surface analy t ical method , XPS.
1　Experimental
1.1　Pulps
Bamboo SCMP was made in laboratory , the brightness of the pulp w as 29.5% ISO.
1.2　Enzymes and enzymatic t reatment
A commercial lipase was provided by Novozymes(China).The conditions for enzymatic t reatment were as fol-
low s:lipase dosage 0 ～ 15 IU/g , pH value 7～ 10 , temperature 25 ～ 55 ℃and time 20～ 60 min.All reactions were
run at 10%pulp consistency.Then the pulps were wellwashed by distilled water.
1.3　Labo ra to ry hydrogen peroxide bleaching
Chelating reaction w as carried out on the enzyme treated pulps for removing harmful metal ions.
The reaction w as run at 10%consistency w ith 0.3% chelating agent(EDTA)and pH 3 for 60 min.Hy-
drogen pero xide bleaching w as then car ried out at the fo llowing condi tions:pulp consistency 20%,
chemical dosage:H2O 2 6%, NaOH 3%, Na2SiO3 3%, MgSO 4 0.3%, temperature 80 ℃, react ion time
180 minutes.All the pulps w ere w ell w ashed by dist illed w ater.The yellow ing of bleached pulp w as
done according to Tappi me thod , and PC numbe r w as calculated as fo llow s:
PC= (1-R∞)2
2R∞ - (1-R∞0)
2
2R∞0 ×100
In which , R∞-brightness af ter ag eing and R∞0-brightness befo re ageing.
1.4　XPS analy sis
Pulp sheets w ere made in a Bǜchner funnel and dried betw een clean blot ting boards at room temper-
a ture.The dry pulp sheet w as then ex t racted by acetone for 6 h.XPS measurements w ere perfo rmed
wi th a Kratos Analyt ical Axis Ult ra Elect ron Spect rometer using a momochromated A1 KαX-ray
source.In order to average over the heterog eneity of the sample , survey scans and high-resolution re-
g ional spect ra w ere recorded from at least three measurement points in each sample.All spect ra w ere
col lected at elect ron take-of f ang le 90°f rom sample areas less than 1 mm in diameter.
The relative amounts of dif fe rent ly bound carbons w ere determined from high-re solution C1s spec-
t ra , using symmetric Gaussians.Bo th the relative peak po sitio ns and relative peak w idths w ere fixed in
the curve fi tt ing proce ss.T he chemical shif t s related to C-C (C1)fo r C-O (C2), O-C-O or C=O
(C3)and O=C-O (C4)were 1.7±0.1 , 3.1±0.1 and 4.4±0.1 eV , respectively.The full w idth at
half maximum(FWHM)of the C -C peak(i.e.carbon atoms w ith no oxygen neighbor s)were kept
20%broader than the rest of the components , due to the slight ly dif ferent binding energies of alipha tic
and aromatic carbon atoms , bo th included in this component.The othe r components were all fi t ted to e-
qual FWHM .The experimental procedure has been described in detail by Johansson et al [ 7] .
1.5　Atomic force micro scopy (AFM)analy sis
Pulp w as dispe rsed in dist illed w ater , and then fibers w as t ransferred into the surface of talc.The
AFM analy sis w as carried out on Nano ScopeTM Illa atomic force microscopy(Veeco M etrolog y , USA)
in S tate Key Lab.o f Pulp and Paper.The image o f A FM was obtained under tapping mode.
2　Results and Discussions
2.1　The ef fect of lipase do sage on brightness and PC value of bleached pulp
As shown in Fig.1 , compared to pulp without enzyme treatment , lipase treatment of bamboo SCMP could in-
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第 6 期 李兵云等:脂肪酶预处理改善粉单竹 SCMP 过氧化氢漂白性能的研究
crease the brightness and its stability.Without lipase pretreatment , the brightness and PC value were 57.6% ISO
and 2.82 respectively.When lipase dosage was 5 IU/g , the brightness rose to 59.1%ISO and PC value dropped
down to 2.32.The brightness reached to maximum 60.4%ISO and PC value continued to drop to 2.03 while lipase
dosage increased to 10 IU/g.But the brightness started to drop as lipase dosage was beyond 10 IU/g.As lipase
treatment could remove some ex tractives on the SCMP fiber surface , the brightness and its stability would be im-
proved as more lipase was applied.But free fatty acid released f rom triglycerides hydrolysis would deposit on the fi-
ber surface[ 4] .So the brightness would go down when lipase usage was over 10 IU/g.
Fig.1　The relationship between enzyme dosage
and the brightness , PC value of the pulp bleach-
ed by H2O2(Consistency 20%, Temp.35 ℃,
Time 30 min , pH 8)
　　　
Fig.2　The relationship between the treatment
temperature and the brightness , PC value of the
pulp bleached by H2O2(Consistency 20%, Lipa-
se 10 IU/g , Time 30 min , pH 8)
2.2　The ef fect of t reatment temperature and pH on the brightness and PC value o f bleached pulp
The effect o f lipase t reatment on the bleachability o f SCMP is determined by enzyme activi ty w hich
is af fected by operating facto rs , such as temperature and pH value.The effects of tempe rature and pH
value on brightness and i ts stabi li ty w ere show n in Fig.2 and Fig .3.With reaction temperature rising ,
the brightness and its stability increased.But the brightness reached to maximum , 60.4%ISO , and PC
number w as 2.03 as temperature w as 35 ℃.Increasing pH value could also improve the brightness , but
had lit t le ef fect on brightness stability .As pH was at 8 , the brightness w ent up to 60.4% ISO , and
then kept a level.T he results indicated that the suitable lipase treatment temperature and pH value w ere
35 ℃ and 8 respectively.
Fig.3　The relationship between the treatment pH
and thebrightness , PC value of the pulp bleached
byH2O2(Consistency 20%, Temp.35 ℃, Time
30 min , Lipase 10 IU/g)
　　　　　
Fig.4　The relationship between the treatment time
and the brightness , PC value of the pulpbleached
byH2O2(Consistency 20%, Temp.35 ℃, Lipase
10 IU/g , pH 8)
2.3　The ef fect of t reatment time on the brightness and PC value o f bleached pulp
As seen in Fig.4 , prolonging t reatment time could improve the brightness and its stability o f
bleached SCMP , but this effect w as no t obvious.Compared w i th the result of time at 20 min , the
brightness for t reatment time at 30 min only increased 1.0% ISO to 60.4% ISO , and PC number de-
creased to 2.03 from 2.14.A nd while treatment time still prolonged the brightness stabili ty started to
go down.The reason is that w hen treatment prolonged to 60 min mo re f ree fat ty acid released f rom tri-
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陕西科技大学学报 第 28 卷
g lycerides hydroly sis deposited on the fibe r surface.
Fig.5　Low-resolution survey scans and high-resolution spectra(lower)from carbon
C1s region for Bambusa chungii SCMP
2.4　Analy sis of surface chemist ry of SCMP fiber by XPS and AFM
In order to determine the chem ical composit ion of the fibe r surface , the oxygen-to-carbon atom ratio
(O/C)derived from the wide spect rum and the percentage of compounds of the C1s signal w ere adopted.
Low and high reso lution spect ra f rom carbon C1s for the samples befo re and af te r lipase pret reatment
w as indicated in Fig.5.The oxygen to carbon ra tios and C1 , C2 and C3 percentage of C1s we re show n in
Tab.1.The relative amount of C-C carbon w as used to calculate the nominal surface coverage of lignin
and ex tractives(Υlignin and Υextractives)[ 8] .The Υvalue describles the area percentage of the surface covered
wi th lignin o r ex t ractives , the Υlignin and Υextractives could be est imated by the equation(1)and(2):
Υlignin=C1extracted pulp-α
49
×100% (1)
Υextractives = C1pulp-C1extracted pulp
C1extractives -C1extractted pu lp ×100% (2)
Tab.1　The O/C ratio and C1s peak areas of Bambusa
　　　　　　chungii SCMP as determined by XPS
O/ C C1s
C1/ % C2/ % C3/ %
FWHM/eV
C1 C2-C3
SCM P 0.40 34.98 44.88 20.14 1.74 1.45
SCMP-E 0.39 30.15 47.04 22.81 1.74 1.45
Lipase 0.43 36.35 48.01 15.64 1.74 1.45
Lipase-E 0.43 34.53 47.74 17.72 1.74 1.45
Where , C1pulp and C1extractived pulp are the
relative amount of the C-C component o f
unex t racted pulp and ex t racted pulp sam-
ple , C1extractive is the contribution to the C1
peak from the pure ext ract ives , i ts value is
94%, and αi s the contribution to the C1
peak from surface contaminant.T he value
of αwas 2%.
The low resolution XPS spectra of Bambusa
chungii SCMP before and af ter lipase pretreatment had C and O as main surface elements(Fig.5).As seen in Tab .
1 , the O/C ratio w as 0.40 , which is similar to those of other TMP and CTMP[ 9] .After lipase pretreatment , the
O/C ratio increased to a value of 0.43.C1 , C2 and C3 in C1s speak indicated the different carbon and carbon linka-
ges in fiber materials.C1 is the C-C and C-H in lignin and extractives , C2 is the C-O in carbohydrates and e-
ther of lignin.C3 is the O-C-O and C=O in lignin and oxidized carbohydrates.The percentages of C1 , C2 and
C3 in C1s on the surface of Bambusa chungii SCMP were 34.98%, 44.88%and 20.14%, respectively.After lipase
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第 6 期 李兵云等:脂肪酶预处理改善粉单竹 SCMP 过氧化氢漂白性能的研究
pretreatment , the percentage of C1 , C2 and C3 in C1s speak on the fiber surface were 36.35%, 58.01% and
Tab.2　The content of lignin and extractives covered on the
　　　fiber surface of different Bambusa chungii SCMP(%)
Υlignin Υext ractive s
SCMP 57.45 7.57
Lipase 66.40 3.05
15.64%.From Tab .2 , it could be found that the
percentages of lignin covered on the fiber surface
before and af ter lipas pret reatment were 57.45%
and 66.40% of the total fiber surface , respec-
tively.And 7.57% and 3.05% of total fiber
surface were covered with extractives before and
after lipase pretreatment.The results indicated that lipase pret reatment could remove some of extractives covered on
the fiber surface , and more lignin on the fiber surface could be explosed , which could improve the bleachability and
Fig.6　AFM image of fiber surface of Bambusachungii SC-
MP(left)and lipase pretreated SCMP(right)
brightness stability of Bambusa chungii SCMP.
AFM image of fiber surface of Bambusa
chungi i SCMP before lipase pret reatment w as
show n in Fig.6.Regular shape of substances(in
cycle)in AFM image w as lignin on the fiber sur-
face , and irregular shape(in rectang le)was ex-
t ractives[ 10] .From Fig.6 , i t could be concluded
that most o f f iber surface of Bambusa chungi i
SCMP was covered w ith lignin and ex t ractives.
After lipase pret reatment , most o f ext ractives
on f iber surface w as removed and there w as
mo re small articles covered on the fiber surface.
3　Conclusions
Lipase t reatment could improve the bleachability and brightness stability of Bambusa chungii SCMP
by removing the ex tractives on the fiber surface.The opt imal conditions of lipase t reatment w ere as fol-
low s:lipase do sage of 10 IU/g , pH value of 8 , tempe ra ture of 35 ℃, pulp consistency o f 10% and time
of 30 min.Under the optimal condit ions , the brightness of the bleached SCMP af ter lipase pret reatment
rose f rom 57.6%ISO to 60.4% ISO and PC number w ould decrease 28% to 2.03.The analy sis results
of XPS and AFM indicated that 57.45% and 7.57% of to tal fiber surface o f Bambusa chung ii SCMP
were covered wi th lignin and ext ractives.And lipase t reatment could remove some ext ractives f rom the
surface of SCMP fiber and mo re lignin w ould be expo sed on the fiber surface.
References
[ 1] Qifeng Yang.Fungal Modification of Eucalyptus Chemitherm omechanical Pulp and Characterization of Fiber Su rface Chemist ry and
Su rfaceMorphology[ D] .Guang zhou:S ou th China University of Tech nology , 2007.
[ 2] Chunhui Zhan g.Study on Dis solved and Colloidal Su bstances in New sp rin t M ill Proces s Water:Characteriz at ion , S tabili ty and En-
zymat ic Cont rol[ D] .Guangzhou:S outh C hina Universi ty of T echnology , 2008.
[ 3] H ata , K., M atsu kura M., Taneda H ., et al..Mill-scale ap plication of enz ymatic pitch cont rol du ring paper production , Enzymes
for pu lp and paper process , American C hemical S ociety , Washing ton DC , 1996:280-296.
[ 4] Kangas H ., Suurnakki A., Kleen M.M odif icat ion of the su rface ch emist ry of TMP w i th enzyme[ J] .Nordic Pulp and Paper Re-
search Journal , 2007 , 22(4):415-423.
[ 5] Dorris , G.M., Gray , D.G..The su rface an aly si s of paper and w ood f ibres by ESCA , Ⅱ .Surface com posit ion of mechanical pu lps
[ J] .Cellulose Chemist ry Techn ology , 1978 , 12(6):721-734.
[ 6] Kan gas H., Kleen M..Su rface chemical and mo rp hological properties of mechanical pulp f ines[ J] .Nordic Pu lp and Paper Research
Jou rnal , 2004 , 19(2):191-199.
[ 7] Johans son L.S., Campbell J.M., Koljonen K., et al..Evaluation of su rface lignin on cellu lose fib ers wi th XPS[ J] .Appl.Su rf.
Sci., 1992 , 92:144-145.
[ 8] sterb erg M.On the Interaction s in Cel lulose Sy stem s:Su rface Forcesand Adsorption[ D] .S tockholm , Sw eden:The Royal Inst i-
tute of Tech nology , 2000.
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陕西科技大学学报 第 28 卷
[ 9] Koljonen K , Osterb erg M , Johansson L S , et a l..Su rface chemist ry and morph ology of dif ferent mechanical pulp s determined by
ESCA and AFM[ J] .Colloid Su rf.A-Phy sicoch em.Eng.Asp., 2003 , 228(1-3):143-158.
[ 10] Gustafs son J.S., H ort ling B., Peltonen J..Scanning prob micros copy and enhanced data analysi s on lignin an d elemental ch lorin
f ree or oxygen delignif ication pine kraft pulp[ J] .Colloid Poly.S ci., 2001 , 279:221-231.
脂肪酶预处理改善粉单竹 SCMP过氧化氢
漂白性能的研究
李兵云1 , 詹怀宇1 , 王双飞2 , 覃程荣2 , 付时雨1
(1.华南理工大学制浆造纸工程国家重点实验室 , 广东 广州　510640;2.广西大学轻工与食品工程学院 , 广
西 南宁　530004)
摘　要:为了提高粉单竹 SCMP 的可漂性和白度稳定性 ,采用脂肪酶对其进行预处理 ,探讨了
脂肪酶预处理工艺参数对其过氧化氢漂白浆白度和白度稳定性的影响 ,并使用原子力显微镜
(AFM)和 X-射线光电子能谱(XPS)对脂肪酶处理前后 SCMP 纤维的表面性质进行了分析.
实验结果表明 ,脂肪酶通过去除粉丹竹 SCMP 纤维表面的抽出物可以提高 SCMP 的可漂性和
白度稳定性;优化脂肪酶处理工艺条件为:脂肪酶用量 10 IU/g ,pH 值 8 ,温度 35 ℃,时间 30
min ,浆浓 10%.AFM 和 XPS 分析结果表明 ,粉单竹 SCMP 纤维表面的木素和抽出物分别占
纤维总表面积的 57.5%和 7.57%;脂肪酶预处理可以去除纤维表面的抽出物 ,使纤维表面暴
露更多的木素.
关键词:脂肪酶;过氧化氢漂白;粉丹竹磺化化学机械浆;X-射线光电子能谱;原子力显微镜
中图法分类号:TS745　　　　文献标识码:A
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