Earticle

This study was carried out to understand the effect of delignification on crystal transformation of alkali-treated wood cellulose by milling and heat-treatment. We used wood flours in different size with 40mesh, 60mesh, 100mesh, 200mesh and wood chips of Paulownia tomentosa for the samples. Control and heat treated samples at 100℃ and 200℃ were examined. The samples were treated with 15% NaOH solution for 10 minutes, and followed by washing with distilled water and dried at room temperature. Additionally, the alkali-treated wood samples were soaked in Schűltz solution for one day and heated at 60℃ for 1 hours, and then washed with distilled water until neutralization. The morphology of wood particles was observed using an optical microscope. Crystalline properties and crystal transformation from cellulose I to cellulose II of the samples before and after delignification were investigated by an X-ray diffraction method. In the X-ray diffraction analysis, it is revealed that the crystal transformation from cellulose I to cellulose II was proceeded easily by delignification. After delignification of alkali-treated samples, also, smaller particle size of wood samples, the more crystal transformation from cellulose I to cellulose II. Moreover, heat-treated samples were more easily transformed to cellulose II structure than control samples.

The objective of this study was to determine the effect of delignification on the properties of bamboo cellulose nanofibers and its nanocomposites. Milled bamboo powder (150-200 mesh) was delignified with sodium chlorite-acetic acid (SC-AA) treatment in reactions 1, 2, 3, and 4 cycles. The delignified bamboo fibers were then fibrillated using wet disk mill (Supermasscolloider MKCA6-2, Masuko Sangyo, Japan). The morphology, functional groups, and crystalline properties of the fibrillation products were characterized. Bamboo cellulose nanofibers and polyvinyl alcohol (PVA) matrix were used to prepare nanocomposites. The physical, optical, and mechanical properties of the nanocomposite were evaluated. The results showed that lignin content of ampel bamboo decreased 12% to 83% after SC-AA delignification. The diameter of ampel bamboo cellulose nanofibers decreased with increasing delignification. The Fourier Transform Infra-Red (FTIR) spectra confirmed that there was a decrease in lignin content although there were still residues left on the cellulose nanofibers. The crystallinity and atomic size of the crystals decreased with increasing delignification reaction. The water absorption and solubility of nanocomposites decreased with increasing delignification reaction on ampel bamboo. Ampel bamboo cellulose nanofibers with 4 times delignification had the highest nanocomposite transparency. Nanocomposite strength increased with increasing delignification.

The lignocellulose has a recalcitrant characteristics that makes it difficult to defibrillation because of its heterogeneous and complex structure. Therefore, the pretreatment is essential to improve for the efficiency of mechanical defibrillation for cellulose nanofibril (CNF) production. Various chemical and biological pretreatment methods have been investigated. Alkali-peroxide treatment has an excellent delignification effect and an environmental benefits due to its low toxicity. In this study, the content of lignin and hemicellulose of Liriodendron tulipifera L. was adjusted by alkali-peroxide treatment with different concentration of hydrogen peroxide. After that, the lignocellulose nanofibrils (LCNFs) were prepared by wet disk-milling. As the concentration of hydrogen peroxide was increased, the content of lignin and hemicellulose was decreased, resulting in improving efficiency of defibrillation. With decreasing content of lignin and hemicellulose, the average diameter of LCNF was decreased, and the filtration time of the LCNF suspensions was increased.

Kraft pulping of Trema orientalis (Nalita) was studied in order to find kinetic data for delignification. Pulping runs were carried out in the temperature range of $160-180\;^{\circ}C$ under constant and well-defined conditions. The delignification was found to be first order with respect to residual lignin and was chemically controlled. The rate of delignification reaction was increased 1.11-1.23 for $10\;^{\circ}C$ temperature increase in the range of $160-180\;^{\circ}C$ range. A mean value of 93% of lignin was removed at the transition between bulk and residual delignification. The influence of cooking temperature on the rate constant was expressed by an Arrhenius-type equation. The obtained activation energy of the delignification reaction was 6,164 cal/mol. The transition point between bulk and residual phase was shifted to lower lignin and carbohydrate yield with the increase of temperature.

The two stage laccase-assisted delignification process led to significant lignin removal in the non-pressurized treatments. It is clearly shown that an alkaline extraction prior to the second laccase treatment significantly increased the overall delignification by ∼15%. This is in line with the contention that the residual lignin has undergone structural changes during the alkaline extraction, and the resulting modified structures are susceptible to the laccase oxidation. In phenolic hydroxyl group, the pre- methylated sample was very responsive to the delignification process. The phenolic hydroxyl groups could be increased during side chain cleavage catalyzed by laccase. This finding demonstrates that the delignification oi etherified structures is an important reaction in the delignificaton by laccase.

Dimethyldioxirane (DMD), which is a source of active oxygen, is effective agent that can be used in chemical pulp bleaching. In this study, delignification of kraft bagasse pulp has been carried out by using DMD. The effect of the applied charge of DMD (as active oxygen) and pH of the delignification medium were studied. The optimum conditions of the applied DMD charge and pH of the delignification reaction were achieved at pH range from 8~9, 2% of DMD (as active oxygen) and the rest of delignification reaction conditions were $25^{\circ}C$, 60 min, and 12% pulp consistency. The development of brightness per unit kappa number removal (ΔBrightness/ Δ Kappa number) has highest value at the optimum condition. The study showed that the reactivity of kraft bagasse pulp be enhanced to wards alkaline hydrogen peroxide bleaching by pulp treatment with DMD.

On nitrobenzene oxidation of aspen, spruce, and knauf wood meals gave rise to vanilline, syrigaldehyde, p-hydroxybenzoaldehyde, vanillic acid, and other minor oxidation products. The phenolic aldehydes (p-hydroxybenzaldehyde, vanilline, and syringaldehyde) are derived from oxidative degradation of the corresponding 4-hydroxyphenylpropane units and their ethers. The lignin content of knauf wood meals was different as the concentration of NaOH solution and cooking temperature. The lignin contents of aspen, spruce, and knauf wood meals were decreased as laccase treatment. The laccase caused C-oxidation, demethylation, cleavage in phenolic groups and C-C cleavage in syrigyl structures.

In previous report, we investigated the impact of hexeneuronic acid and some residual extractiveson lignin determination. These non-lignin components severely interfered lignin content determination which also affect on the oxygen delignification comparison between aspen and pine unbleached kraft pulps. Very different pattern was observed whether based on uncorrected conventional kappa number or based on corrected kappa number in oxygen delignification comparison. Lower kappa number aspen pulps showed poor response to oxygen delignification when kappa number was used as lignin determination method but better response with using the acid lignin method. Phenolic hydroxyl group in kraft pulps were also compared based on uncorrected or corrected kappa numberfor lignin content. Based on uncorrected kappa number, lower kappa number oxygen-delignified pulps had lower phenolic hydroxyl group. However, lower kappa number oxygen-delignified pulps showed much higher phenolic hydroxyl group based on the corrected lignin content. For accurate comparison for residual lignin properties from different pulps, lignin determination should be corrected from non-lignin components contribution to lignin.

선택적 리그닌 분해능을 가지고 생물펄프공정에 사용가능한 백색부후균을 얻기 위하여 94종류의 목재부후균을 검정하였고 선발된 7개종에 대하여 활엽수와 침엽수의 부후능력을 측정하였다. 우선 백색부후균은 셀룰로오즈 분해효소, 페놀산화효소, laccase, peroxidase 등의 효소활성을 간단한 방법으로 검정하여 선발하였는데, Bavendamm test에서 양성을 나타내는 대부분의 균들은 syringaldazine을 사용한 laccase test에서도 강한 반응을 나타낸 반면, 음성반응을 나타낸 대부분의 균들은 laccase와 peroxidase test에서도 음성반응을 나타내었다. 선택적 리그닌 분해능력을 지닌 부후균을 선발하기 위하여 부후균을 은사시나무와 일본잎갈나무(낙엽송) 목재블럭에 접종하여 12주간 배양한 후에 부후된 목재의 중량감소율, 리그닌 량의 감소, 형태적 변화들을 화학분석과 주사전자현미경을 통하여 분석하는 목재부후 실험을 실시하였다. 이 실험에서 사용한 거의 모든 균주는 목재블럭의 중량감소율이 일본잎갈나무 보다 은사시나무에서 2배이상 높게 나타났으며 균을 접종하지 않은 목재블럭에서는 중량감소가 전혀 나타나지 않았다. Ceriporiopsis subvermispora와 Phanerochaete chrysosporium이 다른 균주에 비해서 침엽수와 활엽수의 리그닌을 모두 잘 분해시키는 것으로 나타났으나 분해 능력은 Ceriporiopsis subvermispora가 더욱 우수하였다. Bjerkandera adusta와 미동정된 2균주는 은사시나무에서만 상대적으로 높은 리그닌 분해능력을 나타내었다. B. adusta는 모든 세포벽 성분을 동시에 분해시켜서 2차세포벽을 얇게 만들었으나 다른 균주들은 선택적 리그닌 분해력을 나타내어 두 세포의 세포벽 사이에 위치하는 중벽에 존재하는 리그닌을 분해시켜서 세포를 분리시키는 것이 관찰되었다.

To obtain white rot fungi which have selective delignification capacity and can be used in biopulping processes, 94 different wood rotting fungi were screened and the capabilities of selected species were evaluated on deciduous and coniferous wood blocks. White rot fungi, first of all, were selected by simple enzyme tests, i.e., cellulase activity test; phenol oxidase activity test; laccase and peroxidase activity test. Most organisms that gave a positive Bavendamm gave a strongly positive laccase test with syringaldazine whereas most of those that gave a negative Bavendamm test also negative test for laccase and peroxidase, even if some exceptions were noted. Wood decay experiement were carried out to select fungal species with selective lignin-degrading ability by inoculating selected fungi to both wood blocks of Populus tomentiglandulosa and Larix leptolepis. After 12 weeks of incubation, weight losses, lignin losses, and morphological characteristics of the decayed wood were investigated. Almost all fungi tested caused 2 or more times of weight losses in P. tomentiglandulosa than in L. leptolepis, while no weight losses were detected from the un-inoculated wood blocks. Ceriporiopsis subvermispora and Phanerochaete chrysosporium were the best delignifiers for both hardwood and softwood. P. chrysosporium, however, was less effective than C. subvermispora. Bjerkandera adusta and two unidentified spp. caused delignification for only P. tomentiglandulosa. B. adusta caused simultaneous rot of all cell wall components, resulted in thinning of the secondary cell wall layers. Other fungi caused selective delignification resulting in the removal of lignin from middle lamella and separation of cells from each other.

The compositions of residual extractives in woodmeal, unbleached and oxygen-delignified aspen kraft pulps were investigated with gas chromatography(GC) and gas chromatography-mass spectrometry (GC-MS) with focus on fate of extractives in kraft pulping and oxygen delignification. Steryl esters and shorter retention time (shorter than palmitic acid) extractives were main extractives in aspen woodmeal. Shorter retention time extractives were well removed in kraft pulping. Sterol esters were hydrolyzed to sterols and fatty acids. Sterols and fatty acids were two major extractives classes in unbleached kraft pulps. Linoleic acid was main fatty acids in unbleached pulps compared with palmitic acid which is generally found in aspen woodmeal. Sterolsand fatty acids were also two major extractives classes in oxygen-delignified kraft pulps. However, linoleic acid was well removed in oxygen delignification.

성(省) 에너지적 관점에서 목질자원의 식량자원화의 가능성을 검토하기 위하여 속성수종인 현사시나무를 공시수종으로 하여 alkaline peroxide를 사용하여 탈리그닌화의 적정조건을 규명하였던 바, 25$^{\circ}C$에서 100시간 동안 1% $H_2O_2$(pH 11.5)로 반응시킨 것이 당화율과 분해율이 가장 높았다. 이 조건하에서 생산된 당은 주로 glucose and xylose로 구성돼 있으며, 당화효율과 분해율 무처리재에 비해 각각 260%와 350%의 증가를 나타냈으며, 이같은 조건은 1% NaOH와 20% Peracetic acid로 전처리한 목분의 그것과 대비될만한 것이다.

Alakline peroxide pretreatment for the delignification of poplar wood was performed. sinceit is a simple and efficent method for enhancing the enzymatic digestibility of wood residues. Approximately one-half of their lignin and most of the hemicellulose present in poplar wood were removed when the wood sawdust was reacted at 25$^{\circ}C$ for 100 hrs in an alkaline solution (pH 11.5) of 1% peroxide. The rate of decomposition as well as the saccharification efficiency were enhanced up to 350% and 260% respectively in comparision with those of the controll. This enhancement is comparable with that pretreated with 1% sodium hydroxide and 20% peracetic acid successively. The advantages of alkaline peroxide as delignifying agents against other chemicals were also discussed.

Ethanol production from various agricultural and forest residues has been widely researched, but there is limited information availableon the use of mixed hardwood for ethanol production. The main objective of this study is to assess the impact of time on the steamexplosion pretreatment of waste wood (mixed hardwood) and to determine the convenience of a delignification step with respect tothe susceptibility to enzymatic hydrolysis of the cellulose residue and the recoveries of both cellulose and hemicellulosic sugars. Delignification did enhance enzymatic hydrolysis yields of steam exploded waste wood. For steam explosion pretreatment times of 3and 5 min, the recovery yield of hemicellulosic-derived sugars decreased. The effective hemicellulose solubilization does not alwaysresult in high recoveries of hemicellulose-derived sugars in the liquid fractions due to sugar degradation. In the steam explosion pretreatmenttimes of 3 and 5 min, where hemicellulose solubilization exceeded 95%, but sugar recoveries in the liquid fraction remained below30%. Cellulose to glucose yield losses were less significant than hemicellulosic-sugar losses, with a maximum loss of 24% at 5 min. Up to 80% of the lignin in the original wood was solubilized, leaving a cellulose-rich residue that led to a concentrated cellulose toglucose yield solution (about 50 g/L after 72 h enzymatic hydrolysis in the best case). The maximum overall process yield, taking intoaccount both sugars present in the liquid from steam explosion pretreatment and cellulose to glucose yield from the steam exploded,delignified and hydrolyzed solid was obtained at the lowest steam explosion pretreatment time assayed.

In this study, we separated the lignin from Pinus densiflora by using the acidic catalyst. High boiling point solvents were used to remove the lignin in the pine wood meals. The high boiling solvents used for delignification of pine wood meals are methyl cellosolve, ethyl carbitol, triethylene glycol and methyl isobutyl ketone. Yield and residual lignin of delignified samples were decreased with acidic catalyst content. Residual lignin was the lowest at 5.2% HCl dosage used E-Ca as high boiling point solvents. Also, delignification was the highest at 5.2% HCl dosage used E-Ca as high boiling point solvents. As the results, the optimum high boiling point solvent and acidic catalyst for delignification of wood were E-Ca and HCl, respectively, and the acid catalyst should not exceed a maximum of 5.2%.

In this study, we separated the lignin from the wood by using the high boiling point solvent for developing more environmental friendly pulping method. High boiling point solvents as Ethers, glycols and ketones were used to remove the lignin in the pine wood meals. The Yield and lignin content of residual wood meals was reduced according to the input of the catalyst. Me-C, E-Ca, TEG and MIBK had the best delignification rate of 9 kinds of high-boiling point solvents. At the hydrolysis ratio of the selected solvents, The TEG was highest remain ratio of carbohydrates and the E-Ca was lowest remain ratio of lignin. And the Me-C was most excellent lignin hydrolysis ratio at the low catalyst. The selectivity of delignification of Me-C, E-Ca, TEG and MIBK solvents were 49.6, 49.9, 53.8 and 53.1%, respectively, and its values were similar to those of the commercial Kraft Pulp.

본 연구에서는 고온증기 및 오존 전처리로 제조된 리그노셀룰로오스 나노섬유의 탈리그닌 처리가 나노섬유 및 나노종이의 특성에 미치는 영향을 평가하였다. 형태학적 특성 관찰 결과, 탈리그닌 처리에 의해 평균 직경 35 nm 이하의 균일한 섬유가 얻어졌다. 또한 탈리그닌 처리는 리그노셀룰로오스 나노섬유의 비표면적을 크게 향상시켰으며, 특히 오존 전처리의 경우는 탈리그닌 처리에 의해 무처리에 비하여 1.5배 증가하였다. 나노종이 제조 과정 중의 여수시간 또한 탈리그닌 처리에 의해 크게 증가하여, 고온증기 전처리의 경우는 탈리그닌 처리에 의해 무처리와 비교하여 5.4배 증가하였다. 탈리그닌 처리는 나노종이의 백색도를 향상시켰으며, 고온증기 전처리의 경우는 탈리그닌 전과 비교하여 색상차가 41.9로 매우 높게 나타났다. 나노종이의 인장강도, 탄성율 및 신장율도 탈리그닌에 의하여 크게 향상되었으며, 고온증기 전처리 후의 탈리그닌에 의한 나노종이의 인장강도가 142 MPa로 가장 높게 나타났다.

This study was carried out to investigate the effect of delignification on properties of lignocellulose nanofibers (LCNFs) prepared by wet disk-milling (WDM) after steam and ozone oxidation pre-treatments and their nanopaper sheets. Delignification treatment was effective to obtain fine morphology with uniform fiber diameter less than 35 nm without aggregation, and increased the specific surface area (SSA) and filtration time of LCNFs. In particular, SSA and filtration time of the LCNFs prepared by WDM after ozone pretreatment increased 1.5 and 5.4 times after further delignification. Delignification also increased whiteness and decreased the redness of nanopaper sheets. The highest color difference (41.9) before and after the delignification was obtained in LCNFs prepared by WDM after the steam pretreatment. Tensile properties of nanopaper sheets were also increased by further delignification. The highest tensile strength was found to be 142 MPa.

본 연구에서는 잣나무 목분의 탈리그닌 정도가 습식디스크밀을 이용한 해섬처리의 효율에 미치는 영향과 얻어진 해섬물의 성질을 조사하였다. 또한, 탈리그닌 정도가 종이의 인장강도 특성에 미치는 영향도 조사하였다. 탈리그닌의 정도는 아염소산나트륨과 초산을 사용하는 Wise법의 처리횟수를 달리함으로서 조절하였다. 탈리그닌 정도가 증가함에 따라 해섬효율은 향상되었으며, 디스크밀 처리횟수가 증가함으로서 섬유직경은 감소, 여수시간은 증가하였다. 또한 종이의 인장강도 및 탄성률도 탈리그닌 정도 및 디스크밀 처리횟수가 증가할수록 증가하였다.

In this study, the effect of delignification degree of Korean white pine wood on fibrillation efficiency by wet disk-milling (WDM) and the properties of thus-obtained microfibrillated cellulose (MFC) were investigated. The effect on the tensile properties of nanopaper was also investigated. The delignification degree was adjusted by repeating 'Wise' method using sodium chlorite and acetic acid. The increase in delignification degree improved fibrillation efficiency, showing the smaller nanofiber dimension at the shorter WDM time. The filtration time of MFC water suspension was increased by the increase of WDM cycles. Tensile strength and elastic modulus of the nanopaper were increased by increasing delignification degree and disk-milling cycles.

본(本) 연구(硏究)에서는 효소(酵素) 알칼리 증해(蒸解)의 리그닌 용출거동(溶出？動) 파악하기 위(爲)해 잣나무(Pinus koraiensis S. et Z.) 목분(木粉)을 공시(供試)하여 $110^{\circ}C$, $120^{\circ}C$, $130^{\circ}C$, $140^{\circ}C$, 및 $150^{\circ}C$의 5 수준(水準) 온도(溫度)로 60분간(分間) 1단(段) 등온(等溫) 효소(酵素) 알칼리 탈(？)리그닌 처리(？理)를 행(行)한 후(後), 그 탈(？)리그닌 반응속도(反？速度), 활성화(活性化)에너지 및 반응시간별(反？時間別) 알칼리와 효소(酵素)의 소비동향(消費動向)을 동역학적(動力學的) 방법(方法)으로 구명(究明)하였다. 그 결과(結果)를 보면 탈(？)리그닌은 반응초기(反？初期)에 전(全)리그닌 함량(含量)의 2/5가량이 급속(急速)히 용출(溶出)되는 초기(初期) 산화반응(酸化反？)을 나타냈다. 탈(？)리그닌 반응(反？)의 속도상교(速度常敎)(K)는 반응온도(反？溫度) $150^{\circ}C$의 경우, 소오다법(法)에 비(比)해 3배정도(倍程度) 더 컸다. 본 법(法)의 활성화(活性化)에너지 값은 크라프트나 소오다 펄프법화(法化)보다 1/3정도(程度) 낮은 수준(水準)이었다. 알칼리소비량은 효소(酵素)의 경우와 마찬가지로 반응초기(反？初期)에 총투입량(總投入量)의 1/2가량이 급속히 소모된 후, 완만한 소비협추세(消費趨勢)를 보였다. 탈(？)리그닌 반응속도(反？速度)는 증해과정중 생성되는 유기산(有機酸) 때문에 pH가 감소됨에 따라 크게 영향을 받았다. 또한 증해용출(蒸解溶出)된 리그닌은 잘 침전(沈澱)되지 않을 만큼 저분자화(低分子化) 됨을 알수 있었다. 리그닌의 메톡실기(基)는 급속히 감소(減少)되는데 반(反)해, 페놀성(性) 하이드록실기(基), 카보닐기(基) 및 카복실기(基)는 증가(增加)추세를 보였다.

In order to obtain more detailed information concerning the degradation of lignin in the oxygen alkali pulping single stage isothermal delignification of pine wood meal (Pinus koraiensis S. et Z.) was studied in the oxygen alkali system at five temperature level ($110^{\circ}C$, $120^{\circ}C$, $130^{\circ}C$, $140^{\circ}C$, $150^{\circ}C$) for 60 min.. The rate constant, activation energy, oxygen and alkali consumption during the oxygen alkali delignification were determined by the kinetic method. The 2/5 of total lignin was eliminated at the start of the reaction. The delignification rate constant was about 3 times that of caustic soda pulping. The activation energy was about 1/3 lower than in caustic soda pulping. Like oxygen consumption, alkali consumption was also rapid early at the reaction and almost ceased after about 10 min.. The degradation reaction of lignin was strongly dependent upon the pH decrease of the cooking liquor by organic acid generated in pulping. The lignin in the oxygen alkali pulping degraded into lover molecular weight and had more hydrophillic properties. The methoxyl group decreased considerably at the first of oxygen alkali delignification, while the carbonyl, carboxyl and phenolic hydroxyl group increased rapidly.

목재에 대한 탈리그닌처리에 의한 목재의 흡음성능과 구조적 특징의 변화를 관찰하고자 목재횡단방향으로 채취한 원반형시험편을 탈리그닌처리하여 무 처리 목재와 구조적 특징의 변화를 관찰하고, 흡음율을 측정 비교하였다. 측정주파수범위에서 탈리그닌처리한 시험편이 보통의 시험편보다 높은 흡음율을 나타내었으며, 특히 2~4 KHz의 주파수영역에서는 50% 정도 높은 흡음율을 나타내었다. 또한 탈리그닌처리한 목재는 무 처리 목재보다 중량이 8% 정도 감소하였으며, 탈리그닌처리한 목재의 횡단면에서는 다수의 미세할렬이 발생하여 이들이 흡음공극으로 작용하여 특정주파수영역에서 흡음율이 증가된 것으로 사료된다.

Changes of sound absorption capability and anatomical features of wood by delignification treatment was estimated. Sound absorption coefficients of wood and delignificated wood had been measured by the two microphone method and anatomical changes of delignificated wood examined by SEM observation. The sound absorption coefficients of delignificated wood generally seemed to be higher than those of normal specimen. Especially, in the frequency range of 2 to 4 KHz, they was about 50% higher than those of normal specimen. Abundant small cracks generated on the cross sectional surface of delignificated wood and the weight of delignificated wood decreased about 8% than that of normal wood. It was considered that the small cracks formed by delignification treatment behaved as a sound absorbing pore.