연구논문 : 전기방사를 이용한 리그닌 나노섬유의 제조

이은실 ( Eunsil Lee ),이승신 ( Seung Sin Lee ) 한국의류학회 2014 한국의류학회지 Vol.38 No.3

Lignin is an abundant natural polymer in the biosphere and second only to cellulose; however, it is underutilized and considered a waste. In this study, lignin was fabricated into nanofibers via electros pinning. The critical parameters that affected the electros pin ability and morphology of the resulting fibers were examined with the aim to utilize lignin as a resource for a new textile material. Poly(vinyl alcohol) (PVA) was added as a carrier polymer to facilitate the fiber formation of lignin, and the electros pun fibers were depositedon polyester (PET) nonwoven substrate. Eleven lignin/PVA hybrid solutions with a different lignin to PVA mass ratio were prepared and then electros pun to find an optimum concentration. Lignin nano-fibers were electros pun under a variety of conditions such as various feed rates, needle gauges, electric voltage, and tip-to-collector distances in order to find an optimum spinning condition. We found that the optimum concentration for electros pinning was a 5wt% PVA precursor solution upon the addition of lignin with the mass ratio of PVA: lignin=1:5.6. The viscosity of the lignin/PVA hybrid solution was determined as an important parameter that affected the electros pinning process; in addition, the interrelation between the viscosity of hybrid solution and the electros pin ability was examined. The solution viscosity increased with lignin loading, but exhibited a shear thinning behavior beyond a certain concentration that resulted in needle clogging. Asteep increase in viscosity was also noted when the electros pun system started to form fibers. Consequently, the viscosity range to produce bead-free lignin nanofibers was revealed. The energy dispersive X-ray analysis confirmed that lignin remained after being transformed into nanofibers. The results indicate the possibility of developing a new fiber material that utilizes biomass with resulting fibers that can be applied to various applications such as filtration to wound dressing.

천연재료에 의해 보강된 폴리프로필렌 바이오 복합재의 기계적 물성

여준석(Jun-Seok Yeo),이상원(Sang-Won Lee),황석호(Seok-Ho Hwang) 한국고분자학회 2015 폴리머 Vol.39 No.6

친수성 리그닌 표면을 polypropylene-graft-maleic anhydride(MAPP)로 개질하여 미세섬유상 셀룰로오스와 함께 폴리프로필렌 바이오 복합재의 혼합 보강재로 사용하였다. FTIR과 SEM/EDX를 이용하여 개질 전 리그닌 표면에 MAPP의 화학결합을 통한 리그닌 표면개질을 확인하였다. 리그닌 표면개질 효과를 비교하기 위하여 개질 전 리그닌을 이용한 3성분(미세섬유상 셀룰로오스/리그닌/폴리프로필렌) 바이오 복합재를 대조군으로 함께 비교하였다. 리그닌과 미세섬유상 셀룰로오스의 혼합비율에 따라 폴리프로필렌 바이오 복합재의 열적 특성과 기계적 특성이 의존하였으며, MAPP로 개질된 리그닌(MAPP-lignin)에 의한 3성분 바이오 복합재의 인장강도와 인장탄성률은 개질전 리그닌을 사용하였을 때보다 증가하였다. The surface modified lignin (MAPP-lignin) was prepared by using polypropylene-graft-maleic anhydride (MAPP) and used to fabricate a polypropylene bio-composite as a second reinforcing filler with microfibriled cellulose (MFC). The surface modification of the lignin was confirmed by FTIR and SEM/EDX measurements. The pristine lignin was also used in the MFC/lignin/PP bio-composites as control samples. The thermal and mechanical properties of MFC/lignin/PP bio-composites depended on the mixture ratio of MFC and lignin (pristine lignin or MAPP-lignin) in the MFC/lignin/PP bio-composites. It was found that MAPP-lignin was more efficient to improve tensile strength and tensile modulus in the MFC/lignin/PP bio-composites than those of pristine lignin.

Understanding the relationship between the structure and depolymerization behavior of lignin

Park, Jaeyong,Riaz, Asim,Insyani, Rizki,Kim, Jaehoon Elsevier 2018 Fuel Vol.217 No.-

<P><B>Abstract</B></P> <P>Various lignin depolymerization methods have been proposed. Nevertheless, the relationship between the structure of lignin and its depolymerization behavior has not been widely investigated. Herein, six types of lignin samples were produced from oakwood (OW, hardwood) and pinewood (PW, softwood) using three different delignification techniques (ethanolsolv, formasolv, and Klason). The content of ether linkages in the OW-derived lignins was approximately three times higher than that in the PW-derived lignins because of the presence of the sinapyl alcohol unit in the former. The contents of ether linkages in the lignin isolated via the different methods followed the order: formasolv > ethanolsolv > Klason. The lignin samples were depolymerized in a mixture of supercritical ethanol (scEtOH) and formic acid at temperatures of 250–350 °C. At 350 °C, regardless of the lignin type, high conversion (>95%) and a high bio-oil yield (>81 wt%) could be achieved, demonstrating that the combined use of scEtOH-HCOOH was very effective for the depolymerization of various types of lignin. At the low temperatures of 250–300 °C, the lignin conversion and bio-oil yield were highly dependent on the amount of ether linkages; for example, at 300 °C, the use of OW-derived formasolv lignin resulted in a high bio-oil yield (86.2 wt%), whereas the use of OW-derived Klason lignin resulted in a very low bio-oil yield (27.9 wt%). The properties of the bio-oils produced from the different types of lignin were discussed.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Oakwood lignin contains 3 times higher ether linkage than pinewood lignin. </LI> <LI> Formosolv lignin contains highest ether linkage among the three different lignins. </LI> <LI> Ethanolsolv, Formosolv and Klason lignins were depolymerized in scEtOH and HCOOH. </LI> <LI> High conversion of >95% and high bio-oil yield of >81 wt% were achieved at 350 °C. </LI> <LI> Bio-oil yield depends on amount of ether linkage in lignin sources at 250–300 °C. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

A Concise Review of Recent Application Progress and Future Prospects for Lignin as Biomass Utilization

( Seo-hwa Hong ),( Seok-ho Hwang ) 한국고무학회 2021 엘라스토머 및 콤포지트 Vol.56 No.3

Biomass lignin, a waste produced during the paper and bio-ethanol production process, is a cheap material that is available in large quantities. Thus, the interest in the valorization of biomass lignin has been increasing in industrial and academic areas. Over the years, lignin has been predominantly burnt as fuel to run pulping plants. However, less than 2% of the available lignin has been utilized for producing specialty chemicals, such as dispersants, adhesives, surfactants, and other value-added products. The development of value-added lignin-derived co-products should help make second generation biorefineries and the paper industry more profitable by valorizing lignin. Another possible approach towards valueadded applications is using lignin as a component in plastics. However, blending lignin with polymers is not simple because the polarity of lignin molecules results in strong self-interactions. Therefore, achieving in-depth insights on lignin characteristics and structure will help in accelerating the development of lignin-based products. Considering the multipurpose characteristics of lignin for producing value-added products, this review will shed light on the potential applications of lignin and lignin-based derivatives on polymeric composite production. Moreover, the challenges in lignin valorization will be addressed.

Use and Evaluation of Lignin as Ion Exchangers

Essam. N. Ads,A. M. A. Nada,A. M. El-Masry 대한화학회 2011 대한화학회지 Vol.55 No.1

Modified lignins were prepared. Soda and peroxy lignins were precipitated from black liquor produced from bagasse pulping with soda and peroxyacid pulping process. The precipitated lignins were hydrolyzed using 10% HCl. Different functional groups were also incorporated into lignin by carboxylation and phosphorylation reactions. Moreover crosslinking of these lignins were carried out using epichlorohydrin. Characterization of the modified lignins and lignins derivative were carried out using Infrared spectroscopy. Thermal analysis of these compounds were also carried out using TGA and DTA techniques. Efficiency of sorption of metal ions by the modified lignin was also investigated. It was found that, the peroxylignin and its derivatives show higher efficiency toward metal ions uptake than the soda lignin.

Preparation of Lignin-based Carbon Aerogels as Biomaterials for Nano-Supercapacitor

양봉숙,강규영,정명준 한국물리학회 2017 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.71 No.8

Kraft and organosolv lignins, generally produced in chemical pulping and bio-refinery processes of lignocellulosic biomass, were used to prepare lignin-based carbon aerogels for supercapacitors as raw materials. The difference between lignins and lignin-based aerogels were compared by analyzing physical and chemical properties, including molecular weight, polydispersity, and reactivity with formaldehyde. Also, density, shrinkage, Brunauer-Emmett-Teller (BET) surface area and scanning electron microscope (SEM) images of the lignin-based aerogel were investigated. Kraft lignin consisting of coniferyl alcohol (G) and p-coumaryl alcohol (H) increased the reactivity of formaldehyde, formed a hydrogel well (porosity > 0.45), and specific surface area higher than organosolv lignin. In the case of kraft lignin, there were irregular changes such as oxidation and condensation in the pulping process. However, reaction sites with aromatic rings in lignin impacted the production of aerogel and required a long gelation period. The molecular weight of lignin influences the gelation time in producing lignin-based aerogel, and lignin composition affects the BET surface area and pore structures of the lignin-based carbon aerogels.

Thermoalkaliphilic laccase treatment for enhanced production of high-value benzaldehyde chemicals from lignin

Yang, Youri,Song, Woo-Young,Hur, Hor-Gil,Kim, Tae-Young,Ghatge, Sunil Elsevier 2019 INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES Vol.124 No.-

<P><B>Abstract</B></P> <P>Enzymatic conversion of lignin into high-value chemicals is a key step in sustainable and eco-friendly development of lignin valorization strategies. In the present study, a novel thermoalkaliphilic laccase, CtLac, from <I>Caldalkalibacillus thermarum</I> strain TA2.A1 was tested for the depolymerization of lignin and the production of value-added chemicals, using three different lignocellulosic biomass, organosolv lignin (OSL), and Kraft lignin. Seven valuable lignin monomers were identified from the CtLac-treated samples using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Remarkably, increases of 22.0%, 65.6%, and 27.3% of <I>p</I>-hydroxybenzaldehyde and increases of 111.1%, 93.5%, and 238.1% of vanillin were observed from rice straw, corn stover, and reed, respectively. Comparative analysis of lignin monomers released from rice straw, using <I>Trametes versicolor</I> laccase (TvL) and CtLac indicated efficient depolymerization of lignin by CtLac. CtLac treatment resulted in 2.3 fold and 5.6 fold, and 1.9 fold and 2.8 fold higher amounts of <I>p</I>-hydroxybenzaldehyde and vanillin from OSL and Kraft lignin, respectively, compared to CtLac-treated rice straw samples after 12 h reaction. OSL was the best substrate for the production of benzaldehyde chemicals using CtLac treatment. The results demonstrated potential application of bacterial laccase CtLac for valorization of biomass lignin into high-value benzaldehyde chemicals under thermoalkaliphilic conditions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A novel thermoalkaliphilic laccase CtLac, was investigated for lignin depolymerization. </LI> <LI> Lignin monomers released after CtLac treatment were analyzed using HPLC-MS/MS analysis. </LI> <LI> High-value benzaldehyde chemicals <I>p</I>-hydroxylbenzaldehyde and vanillin were released from lignin after CtLac treatment. </LI> <LI> CtLac treated Organosolv lignin released highest amount of benzaldehyde chemicals. </LI> <LI> CtLac favored depolymerization of lignin under thermoalkaliphilic conditions. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Improvement of lignin oil properties by combination of organic solvents and formic acid during supercritical depolymerization

Park, S.Y.,Hong, C.Y.,Jeong, H.S.,Lee, S.Y.,Choi, J.W.,Choi, I.G. Elsevier Scientific Pub. Co 2016 JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS Vol.121 No.-

Supercritical treatment of ethanol organosolv lignin was conducted to produce lignin-derived bio-oil. The reaction was performed at 350<SUP>o</SUP>C for 40min with 3MPa hydrogen gas pressure. To improve the yield of lignin oil and inhibit repolymerization during supercritical treatment, formic acid was added to the solvent. The effect of formic acid was examined by gas chromatography mass spectrometry (GC/MS), gel permeation chromatography (GPC), and elemental analysis. The maximum yield of lignin oils was shown to reach up to 70wt% with the addition of formic acid. When 7% formic acid was used, the resulting lignin oil exhibited the highest monomer content at approximately 56mg/g and the lowest oxygen/carbon molar ratio (O/C) of 0.26. The main degradation products in the lignin oil were syringol, 4-methylsyringol, and p-cresol. The lignin oil contained a larger proportion of syringyl unit monomers than guaiacyl because yellow poplar is hardwood, consisting primarily of syringyls. The molecular weight of lignin oils increased with the addition of formic acid since lignin-derived oligomers were also produced. Meanwhile, experiments were performed using methanol and isopropanol to investigate the relationship between the solvent type and lignin depolymerization. Isopropanol led to a higher yield of lignin oil compared to ethanol, but amounts of monomeric products were much lower. Therefore, supercritical ethanol treatment with 7% formic acid under pressure from hydrogen gas is considered to be more effective when compared to other conditions, and this procedure demonstrated the possibility for better production of lignin-derived products during thermal decomposition reactions.

Effects of lignin on the volume shrinkage and mechanical properties of a styrene/unsaturated polyester/lignin ternary composite system

Yeo, Jun-Seok,Lee, Ji-Hoon,Hwang, Seok-Ho Elsevier Science Ltd 2017 Composites Part B, Engineering Vol.130 No.-

<P><B>Abstract</B></P> <P>A pristine lignin and chemically surface modified lignin were used as a low profile additive and reinforcing filler for unsaturated polyester (UPE) resin. The chemical modification for pristine lignin was confirmed by FT-IR and SEM/EDX. Two different styrene/unsaturated polyester/lignin ternary composite series were prepared by using the pristine lignin or allyltrimethoxy silane (VPS)-modified lignin (VPS-lignin) to investigate volume shrinkage behavior and the mechanical properties of the UPE composites according to the lignin filler contents. The tensile and impact properties of the UPE composites showed that VPS-lignin/UPE composites performed better than the pristine lignin/UPE composites due to improved interfacial adhesion between the lignin filler and UPE matrix. However, the results of the volume shrinkage behavior in the UPE composites showed that the pristine lignin was more efficient than the VPS-lignin due to the many micro-voids formed from poor interface adhesion between them.</P>

Construction of sustainable polyurethane-based gel-coats containing poly(<i>ε</i>-caprolactone)-grafted lignin and their coating performance

Jang, Su-Hee,Kim, Dae-Hoon,Park, Dong Hyup,Kim, Oh Young,Hwang, Seok-Ho Elsevier 2018 Progress in organic coatings Vol.120 No.-

<P><B>Abstract</B></P> <P>In order to use a lignin as a polyol in polyurethane-based gel-coated films, poly(ε-caprolactone) grafted lignin (PCL-<I>g</I>-lignin) was synthesized by a ring-opening polymerization of ε-caprolactone in presence of a pristine lignin. This reaction was confirmed by FT-IR spectroscopy. By usage of the PCL-<I>g</I>-lignin, polyurethane-based gel-coated films was prepared through a simple urethane reaction following which the effects of the PCL-<I>g</I>-lignin content on the physical properties and surface characteristics of the polyurethane-based gel-coat films was examined. With increased PCL-<I>g</I>-lignin content, the decreased cross-linking density resulted in the reduction of physical properties such as the tensile strength and surface hardness of the gel-coated films. Their surface characteristics (e.g., adhesion strength, abrasion, and gloss) were constant, regardless of the PCL-<I>g</I>-lignin content increase in the gel-coated films.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A poly(ε-caprolactone) grafted lignin (PCL-<I>g</I>-lignin) was synthesized through ring-opening polymerization with ε-caprolactone. </LI> <LI> By usage of the PCL-<I>g</I>-lignin, polyurethane-based gel-coated films was prepared. </LI> <LI> With increased PCL-g-lignin, the physical properties of the gel-coated film were decreased. </LI> <LI> Their surface characteristics were constant, regardless of the PCL-<I>g</I>-lignin content increase in the gel-coated films. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Using the poly(ε-caprolactone) grafted lignin (PCL-<I>g</I>-lignin), the sustainable polyurethane-based gel-coats were fabricated and their physical properties and surface characteristics were investigated.</P> <P>[DISPLAY OMISSION]</P>