جستجوی مقالات مرتبط با کلیدواژه « لیگنین » در نشریات گروه « صنایع چوب و کاغذ »

Lignin, a polymer found in wood with carbon content up to 60 %, has potential applications in producing porous carbon as an adsorbent material, but its synthesis using chemical activation requires a large amount of activating agent, which can cause production problems. To address this issue, the study examined the effect of adding acrylic acid to lignin during the hydrothermal process to reduce potassium hydroxide consumption in porous carbon production. Results showed that adding acrylic acid increased surface area from 283 m2/g to 653 m2/g, and also, the maximum lead adsorption capacity of 196 mg/g was achieved by the synthesized porous carbon.

The production of a coating agent based on the extracted lignin from black liquor of bagasse soda pulping was investigated. The crude lignin was modified via sulfomethylation method to increase its solubility. Both unmodified and sulfomethylated lignins were applied on the testliner papers with and without starch and physical, surface and mechanical properties of the coated testliners were evaluated. The viscosity of coated solution containing 100 percent of crude lignin was very low and similar as that of water. Addition of starch to coating solution resulted in increasing of the viscosity of formulation. Evaluation of hydrophobicity of coated testliners showed that compared to papers treated with unmodified lignin and starch, the papers treated with sulfomethylated lignin had significantly lower water absorption, wetting rate, absorption rate of water droplet, which resulted in hydrophobicity of papers. Colorimetric analyses showed a decrease in lightness (L*) of the coated testliners with only unmodified lignin compared with untreated control ones. In contrast, the lightness of testliners coated with sulfomethylated lignin was significantly improved and was almost as high as control samples and samples, which coated by the starch solution without lignins. Air permeability of the coated testliners with only lignin was significantly lower than that of lignin-starch coated samples. The results also showed that the tensile indices of samples coated with unmodified and modified lignins were significantly higher than that of control ones. The tensile index of testliners coated with starch-lignins solutions was almost near to that of samples treated with only starch solution.

Conversion of renewable and sustainable materials to valuable products is a known way to replace synthetic polymers with natural polymers. lignin is a bio-renewable material and it is the second most abundant biopolymer from biomass. In this work, lignin-based hydrogel was synthesized by crosslinking reactions between dialdehyde cellulose and aminated lignin. Lignin was subjected to amination by Mannich reaction and cellulose was oxidized by sodium metaperiodate, which has been confirmed by FTIR spectroscopy too. The FTIR spectroscopy of the produced hydrogel showed that aldehyde groups of oxidized cellulose react with the amino groups of aminated lignin through a Schiff base, which provide the successfully crosslinking for construction of a hydrogel network. SEM revealed a porous architecture of hydrogel with different pore size distributions. The surface Properties of hydrogel was determined by BET analysis, which indicated the internal porosity of the hydrogel. The results confirmed that the aminated lignin-based hydrogel prepared in this research is a sustainable green hydrogel, which would be beneficial for different applications.Conversion of renewable and sustainable materials to valuable products is a known way to replace synthetic polymers with natural polymers. Lignin, bio-renewable material, is the second most abundant biopolymer from biomass. In this work, the lignin-based hydrogel was synthesized by crosslinking reactions between dialdehyde cellulose and aminated lignin. So lignin was subjected to amination by Mannich reaction and cellulose was oxidized by sodium metaperiodate, which has been confirmed by FTIR spectroscopy results. The FTIR spectroscopy of the produced hydrogel showed that aldehyde groups of oxidized cellulose react with the amino groups of aminated lignin through a Schiff base, which provides the successful crosslinking for the construction of a hydrogel network. SEM revealed a porous architecture of hydrogel with different pore size distributions. The surface properties of hydrogel were determined by BET analysis, which indicated the internal porosity of the hydrogel. The results confirmed that the aminated lignin-based hydrogel prepared in this research was a sustainable green hydrogel, which would be beneficial for different applications (hygiene, agriculture, etc).

This study uses soda lignin to modify it with furfural as adhesive on the physical and mechanical properties of plywood Poplar wood. Producing plywood, pure Lignin (L.100%), lignin-furfural 30% (L.70-F.30), lignin- furfural 60% (L.40-F.60) were used as the adhesive at three different levels ( 120 140 160gm2) accompanied with ammonium chloride (1%) as the hardener and wheat flour (30%) as the filler based on the dry weight of the adhesive. Plates made with urea formaldehyde resin at 160 g/m2 were produced as control samples. characteristics of adhesives included solid material percentage, viscosity, specific weight and PH were measured. After producing the laboratory boards, the physical and mechanical properties of samples, such as thickness swelling after 2 and 24 hours of being soaked in water, shear strength, modulus of rupture, and modulus of elasticity were measured. The results indicate that independent and interactive effects of adhesive and its consumption level on the physical and mechanical properties of plywood are not statistically significant. And in all cases, the control boards had better properties than the lignin adhesives

Nowadays, finding a catalyst with high quality and eco-friendly thermoset resins is very valuable. This study aimed to investigate the effect of maleated lignin-based polyacid (MA-PL) as a catalyst in urea-lignin-glyoxal (ULG) resin. For this reason, a phenolate reaction was done to increase the hydroxyl groups of lignin. Then the modified lignin was reacted with maleic anhydride to obtain polyacid based on maleated lignin. In the next step, different content of MA-PL catalyst (0, 1, 2, and 3 wt%) was added to ULG resin and prepared resins were used in particleboard panels production. Different properties of synthesized resins and panels were measured according to standard methods and were compared with those using ammonium chloride as the control sample. In addition, the thermal behavior of resin before and after adding catalyst was analyzed with Differential Scanning Calorimetry (DSC). Generally, the results of this research indicated that polyacids based lignin could be used as a suitable catalyst for ULG resin. Physical and mechanical test analysis indicated that the addition of catalyst from zero to 3 wt% continuously decrease pH and gelation time. DSC analysis showed that adding extra MA-PL reduces the curing temperature of resin compared with ammonium chloride. Based on the obtained results from manufactured panels, mechanical strength (MOE, MOR, and IB strength) and dimensional stability of the panels was improved by adding 3 wt% MA-PL.

Black liquors are produced as a byproduct of chemical pulping and About 500 million tons of black liquor are produced annually in pulp mills around the world, of which about 95% for fuel consumption and only 2% for the production of special products with higher added value are used. In order to recover more effectively, acidic precipitation of black liquor using gas injection pretreatment has been studied recently. Previous studies have shown the advantage of carbon dioxide injection as pretreatment to reduce sulfuric acid consumption, increase yield and purity of lignin. The Iranian’s pulp and paper mills have the potential to recover lignin, which is burned as fuel. Therefore, this study was performed to investigate new methods of lignin recovery on hardwood Kraft black liquor in Iran. Pretreatment was done using carbon dioxide injection in lignoboost method as well as two-stage oxygen-carbon dioxide injection in Lignoforce method under 2 bar pressure and 80 ° C on Kraft black liquor, Then, the pH was decreased to 2-3 using 6 M sulfuric acid to precipitate the lignin, which was then separated by filtration and washed with water. Finally, the recovered lignin was dried at 50º C. TGA, FTIR, SEM and AFM tests were performed to evaluate the thermal stability, chemical structure, morphology and dimensions of recovered lignin. Also, acid consumption, yield and ash content were calculated. The amount of acid consumed and the ash percentage of lignin recovered from gas injection processes was less than the non-injection method. In addition, the oxygen-carbon dioxide injection method showed higher efficiency compared to the carbon dioxide injection. FTIR results demonstrated a similar chemical structure in the recovered lignin. AFM and SEM images of lignin produced by pretreatment with carbon dioxide injection showed larger particles as well as higher thermal stability compared to oxygen-carbon dioxide injection.

In this study, the effects of drought, fertilization, wounding and bending treatments were investigated on the content and composition of wood lignin in two-year-old eucalyptus seedlings (Eucalyptus camaldulensis). Results showed that drought-induced xylem had the highest concentration of lignin and guaiacyl (G) units and the lowest amount of hydroxyphenyl (H) and syringyl (S) units as well as the lowest S/G ratio compared with other treatments. In contrast, the lowest concentration of lignin and G units and the highest amount of S units and the highest S/G ratio were observed in fertilization treatment. Due to this treatment, H units increased. After wounding, lignin concentration did not change significantly compared with the control treatment and only slightly decreased. However, as a result of this treatment, G units increased significantly and H and S units and S/G ratio decreased. The most important chemical change observed in bending treatment was a sharp increase in H units and a decrease in guaiacyl and syringyl and an increase in the S/G ratio. Overall, it can be concluded that the chemistry of xylem is altered to give the plant the best ability to withstand environmental stresses. Guaiacyl lignin has a more protective role, and increased H lignin is associated with increased growth rate or increased stem flexibility.

This study uses the Lignin-Glyoxal adhesive to replace chemical resins with environmental compounds producing plywood. producing plywood, pure Lignin (L.100%), lignin- glyoxal 15% (L.85-G.15), lignin-glyoxal 30% (L.70-G.30) and Urea-formaldehyde (control) were used as adhesive at 160 gr/m2 level. Accompanied with ammonium chloride (1%) as the hardener and wheat flour (30%) as the filler based on the dry weight of the adhesive characteristics of adhesives included solid material percentage, viscosity, specific weight and PH were measured. After producing the laboratory boards, the physical and mechanical properties of samples, such as thickness swelling after 2 and 24 hours of being soaked in water, shear strength, modulus of rupture, and modulus of elasticity were measured. In addition, the groups and bonds in the pure lignin and lignin-gloxal adhesives were identified by Fourier Transform Infrared (FTIR) spectroscopy. The results indicated that the independent effect of adhesive type on the thickness swelling of plywood after 2 and 24 hours was significant. Although the results suggest that modifying the lignin would improve the plywood in all cases, the control boards had better featurers than those made with the Lignin-Glyoxal adhesive.

Bagasse carbohydrates, which are mainly consist of cellulose and hemicelluloses, are important raw materials in chemical industries; because they can be easily prepared from biomass in large scale, their application is simplified in large scale. Derivation and purification of biomass chemicals are difficult, costly and require the use of complex methods with environmentally dangerous chemicals and solvents. Therefore, researchers are looking for simpler, cheaper, safer and environmentally friendly compounds and processes. The use of deep eutectic solvents has been reported as one of these methods in biomass processing. In this study, the use of new oxalic acid-choline chloride and lactic acid-choline chloride deep eutectic solvents for bagasse treatment was investigated. Results indicated that these new solvents were effective in the solubilization and extraction of short-chain and amorphous carbohydrates, especially hemicelluloses; as the final processing yields were respectively reduced to about 50 and 59%, and the main part of degradation belonged to the hemicelluloses. Cellulose to holocellulose ratio was increased in all treatments to about 90%. The lactic acid-choline chloride solvent was effective in lignin solvation, as the lignin content was reduced to 6.2%, while oxalic acid-choline chloride solvent did not have an ideal efficiency toward lignin removal, and the least amount of lignin in treated product was about 11%. Also, the viscosity drop of cellulosic pulp in lactic acid-choline chloride solvent-treatment was much less compared to oxalic acid-choline chloride solvent-treatment, as the cellulosic pulp viscosity for these treatments were 11.1 and 4.3 cp., respectively.

According to the importance of urea formaldehyde resin in plywood industry and to replace a suitable filler for this resin with wheat flour (common filler), lignin drived from three black liquors including alkaline sulfite-AQ, soda-AQ and Kraft evaluated as filler-extender for urea formaldehyde resin in the plywood manufacture. For this reason any of the four types of lignins were used at 0, 10, 20 and 30% dry weight of resin.After that, the physical and mechanical properties of samples including thickness swelling after 2 and 24 hours immersion in water, flexural strength and modulus of elasticity parallel and perpendicular to fiber the surface layer and shear strength were measured.The results of this study showed that increasing thelignin of alkali sulfite-anthraquinone and then kraft lignin, flexural strength and modulus of elasticity parallel to the fiber surface layer increased.Also, the bonding shear strength of the samples using three types of lignins increased. On the other hand, the use of these three types of lignin, improved the dimensional stability of the boards.The results show the superiority of lignin from alkaline sulfite anthraquinone process compared to other lignins to improving the mechanical properties of plywood.

In this study, the liquorice root (Glycyrrhiza glabra) has been extracted in the Liquorice factory of Kerman, supplied as raw material. The above mentioned waste, after pre-hydrolyzed with sulfuric acid 2% at 130 °C in 60 minutes, is cooked at temperatures of 170 ̊C, the chemicals charge of 20%, and in four times 15, 30, 60 and 90 minutes and rate of liquor to waste 7:1 in Soda process. Obtained Soda pulps were evaluated in yield, lignin percentage, water retention value (WRV), viscosity and crystallinity. Results showed that by prolonging of cooking time, pulp yield and lignin percentage were decreased and WRV increased. Also, pulp viscosity in 30, 45 min was increased by increasing in cooking time that according to other results, it seems that it is false viscosity. In addition, accordance with characterizing of samples by XRD, by progressive cooking time from 15 to 45 min, sample crystallinity decreased and in 60 min its value is increased. According to the pulps viscosity and downward trend of lignin removal with progressive cooking time, this addition can be due to crystallization of hemicellulose like xylan on the crystalline zone of cellulose chain. Therefore, according to the results and based on Bio-refinery concept, cooking time 30 min suggested as the best option for production of high value-added products in saccharification process.

Mazandaran wood and paper industry is known as the largest manufacturer of paper in the Middle East. Black liquor is liquid product of pulp cooking chemical process, which is much polluted because of some organic and inorganic compounds. So, chemical and energy recovery of black liquor are one of the interesting studies. There are different ways for this one among them concentration method of liquor is used in Mazandaran wood and paper industry. In this work, Condensing unit of liquor was simulated by Hysys software. Then, simulation results were compared with factory data and acceptable results were obtained. In the next step, the effect of operating conditions of the two main feed streams was studied. The results showed that with increasing of dilute liquor temperature, concentration of output liquor flow increases as per 40°C increasing of temperature, almost 28 percent of the condensed value increases. Also, by 10 kPa increasing of the dilute liquor pressure, approximately 39% of condensed value decreases. By increasing the pressure and flow rate of steam, concentration of output liquor somewhat increases, while, this increasing for flow rate, is initially steep and then less steep. The effect of steam temperature on the concentration of output liquor at different pressures must be checked individually.

In this research, two types of lignin, i.e. one extracted from industrial waste water of the Iran wood and paper (choka) factory as black liquor and another provided from Aldrich company, were studied. Firstly, the lignin was precipitated from its black liquor by a dilute acid and was then purified by dissolving in tetrahydrofuran (THF). Lignin samples were characterized using Fourier transform infrared (FTIR) and proton nuclear magnetic resonance (1HNMR) spectroscopies. It was found from results that the Aldrich lignin has a structure similar with the lignosulfonate while lignin extracted from black liquor does not have a hydrophilic sulfonate group and has a Kraft lignin structure. Using acetylation of Kraft lignin and complementary characterization with 1HNMR spectroscopy, the ratio of hydroxyl functional groups to methoxy groups was calculated to be 1.11 to 1, and amount of the hydroxyl groups was calculated to be 5.91 mmol/g of acetylated lignin, where 53% of the hydroxyl groups is related to the aromatic hydroxyl groups. By having the molecular weight of the Kraft lignin which was obtained from the gel permeation chromatography (GPC) analysis of the acetylated Kraft lignin to be 1260 g/mol, average number of the hydroxyl groups per acetylated lignin chain was calculated to be 7.44.

Athel tamarisk (Tamarix aphylla) is a fast growing, evergreen tree succeeding in the most soils and can tolerate the saline conditions. Despite its ecological importance and wide distribution in central and southern parts of Iran, wood properties of this species has little been concerned. However, the potential of this species in cellulosic industries of Middle East dry countries has recently been focused. Hence, to study wood anatomy and physical and chemical properties of Athel tamarisk, 3 stands were selected and felled from the Zabol region (Sistan and Baluchestan province). Wood anatomical features of this species were studied and listed according to the list of microscopic features for hardwood identification by IAWA Committee. In addition, lignin distribution in xylem was studied using fluorescence microscopy. Calculating fiber biometry features assessed that although fiber quality is not perfect but meets the standards of paper production, comparing other commercially used hardwoods in this industry. According to chemical composition analysis, cellulose content of this wood is rather low (39%) which could be a result of large amount of thin-walled paranchyma cells in xylem. Lignin content is a bit higher than average hardwoods and this component is concentrated in vessels and fibers. Physical properties of studied wood samples (specific gravity and shrinkage values) were in the range of other light-weight and fast growing hardwoods and thus this wood is expected to have similar end-use quality.

This study lignin from unbleached hardwoods chemimechanical pulp was extracted and the chromophor functional groups of the lignin were studied. Acetylation and reduction treatments were perfomed and samples were analyzed by FT-IR spectroscopy. A mild acidic dioxin extraction method was employed to isolate lignin. For the acetylation and reduction treatments of lignin acetic acid and sodium borohydride were used respectively. The results of untreated and treated (acetylated and reduced) lignin spectra showed that، the major of lignin chromophor groups such as hydroxyl and carbonyl groups have been reduced or eliminated by these treatments. In the acetylated lignin، the absorption band of hydroxyl groups has been weakened and in the 1743. 16 Cm-1 region، acetoxy compounds band has appeared and also a cluster absorption band was observed in the 1228. 76 Cm-1 region. In the reduced lignin، most of the absorption bands of the carbonyl groups have been weakened or eliminated، especially in the 1705. 56 and 1629. 54 Cm-1 region.

The influence of fiber lignin content and the dosage of coupling agent on the strength and physical properties of cellulosic fiber-polypropylene composite were investigated. The old corrugated container (OCC) fibers were delignified using sodium hydroxide to reach the lignin content of 2. 7، 3. 78، 5. 26 and 7%. Fibers were compounded with polypropylene by extrusion process using 20% fibers and 77% PP and the extrudate was cooled and grinded to fine granulates before injection molding. MAPP coupling agent was applied at three different levels (1، 2 and 3 percent based on the total weight of the composite). The strength properties of the composites were measured using relevant ASTM test methods and the results were statistically analyzed using factorial experiment under complete randomized design. The impact of fiber lignin content of flexural strength of composite was statistically significant at 98 percent significance level and the lowest and highest values of flexural strength of composite were measured at 3. 78 percent and 7 percent lignin content of fiber. The interactive effect of fiber lignin and MAPP on the tensile strength and flexural modulus of elasticity of the composite showed that at lower values of lignin and higher dosage of MAPP، these properties are 38. 7 and 3438 MPa respectively. Other strength values of the composites were also improved and at lower content of lignin and increaing dosages of the MAPP، the impact strength of the composites was increased from 52. 82 J/m to 60. 26 J/m.

In this research، For Vanillin preparation from lateral product of pulping factory، first، lignin was extracted from kraft cooking liquors of softwood (pinus eldarica) and the FT–IR spectrum of lignin was investigated and it was compared with standard. The amount of extracted lignin was 27% based on oven dry weight of wood. Then vanillin is prepared by oxidation of lignin under pressure. Finally the vanillin concentration in product solution was analyzed with FT–IR and HPLC. The yield obtained from this work was around 4. 2% (wt vanillin / wt lignin).

In this study, changes in optical behavior of poplar Kraft lignin and bagasse Soda lignin, before and after reducing with sodium borohydride and sodium hydrosulfite (dithionite) and also after methylation using dimethyl sulfate, was monitored by measuring optical indices (brightness, k/s, whiteness and Post-Color numbers) of impregnated papers following accelerated thermal aging. The structural changes in lignins caused by reductive reactions, were mostly verified by using absorbance changes (UV-Vis spectrometry) and FI-IR spectroscopy. It was observed that, regarding elimination of chromophoric carbonyl and quinone groups, sodium borohydride showed better and more sustainable performance than sodium hydrosulfite. Therefore, it could be inferred that to improve the brightness of lignin-containing papers and persistance of this brightness, sodium borohydride could exhibit more efficiency and higher applicability.

In this paper, a novel enzymatic method was evaluated for isolation and purification of wood lignin. The chemical structure of enzymatic lignin (Cellulytic lignin) was compared with conventional Bjorkman method (Milled wood lignin). The chemical structure elucidation was performed with FTIR, quantative 13CNMR, basic elemental analysis and Gel Permeation Chromatography (GPC). The results showed that enzymatic lignin preparation has a better chemical structure than MWL. Comparing to conventional isolation methods, application of an enzyme sequence with reduced milling time could lead to a mild extraction with less structural degradation of lignin. Resulting lignin could be more representative for wood lignin than milled wood lignin.

Okaliptus is a fast –growing and light – liking tree that its trunk is smooth and is shelled spontaneously. n a short time its diameter and height increase.for its fast growing. So that turing it into things is difficult Fiber s traction is high and deksity is 0.55 to 0.58 a square centimeter.The samples were prepared from the branches and trunk of Ocalyptus Kameldolensis with the average old of three years, from Jiroft region in Kerman province. After ordaining the age and having samples from the same age, some discs were prepared for cutting to measure fibers.Making ready and suspension of fibers were done in Fraklin method. Measuring amaout of lignin was done to standard no: T222- om – 88 and TAPPI guide directions. Measuring cellulose was done according to Nitric Acid method and due to standard No: T264 – om – 88, and TAPPI guide directions. Due to results the length of trunk fibers was 811.36 and branches was 845.68 micro meters.Diameter of trunk fibers is 19.3 but branches 15.64, these amounts don,t have a meaningful differnce the level of 5&1 percent. Diameter of the carity of rrunk fibers was 10.71, but branches 3.44 at the level of 5&1 percent, they don,t have a meaningful difference. The amount of extracted articles of trunk is 4/5 but branches 2.3 percent, and amount of lignin in trunk was 35.66 but in the branch 24.66, and amount of cellulose in trunk was 55.66 and the branch 46.81 percent which at the level of 5&1 percent have a meaningful difference. The amount of Ashes from trunk was 0.73 but from the branch 0.88 that at the level of 5&1 percent, don,t have a meaningful defference.