جستجوی مقالات مرتبط با کلیدواژه « لیگنین » در نشریات گروه « جنگلداری »

The aim of this study was to compare nanolignin and ionic liquid (IL)-treated lignin as new compatibilizers in Wood-Plastic Composites (WPC). For this purpose, lignin was extracted from black liquor and modified with [Emim][OAc]. Then, the modified lignin was used as a compatibilizer in the WPC.  Nanolignin was prepared by an acidic method, and its performance was compared to that of ionic-liquid-treated lignin as a compatibilizer in the composites. Nanolignin and ionic liquid-modified lignin at the same levels (1, 3, and 5 wt%) were added to the wood flour and polypropylene mixture, and WPCs were manufactured using the hot press method. In the next step, all physical and mechanical properties of the prepared panels were analyzed using standard methods. FTIR analysis indicated that modification of lignin by an ionic liquid can change some chemical bonds and even produce new bonds.  However, the chemical structures of the virgin lignin and nanolignin were similar. The physical and mechanical properties of the prepared composites indicated that the addition of both forms of lignin significantly increased the dimensional stability, bending properties (flexural modulus and flexural strength), and impact strength of the composites. Based on the findings of this research, IL-treated lignin exhibited better physical and mechanical results as a coupling agent in wood plastic composites compared to nanolignin; thus, the composites with 5 wt% have the highest mechanical strength and dimensional stability among all lignin-containing samples.

In this study, efficient hybrid hydrogels as drug delivery platforms were synthesized using Kraft lignin, a biopolymer obtained from the alkaline paper industry, chitosan and glutaraldehyde as a crosslinker. The ratio of lignin was an important variable factor of this study and its effect on morphology and mechanical properties were studied. The characteristics such as compressive property, swelling capacity, drug release, degradation time, and SEM imaging of the hydrogels of chitosan and chitosan/ lignin with different amount of lignin were investigated. Also, paracetamol drug was selected as a drug model. The results showed that the glutaraldehyde crosslinker can effectively create a crosslinked structure, so that the durability and stability of the hydrogels in the desired conditions is up to 15 days for the pure chitosan sample and 11 days for the lignin chitosan sample, respectively. Although the shortest shelf life (5 days) corresponds to the highest amount of lignin, which was a shorter period of time, but it gives enough time for the drug to be completely released. The results showed that although the hydrogel structure is weakened by increasing the percentage of lignin, the drug was released faster with the increasing of lignin, which can be considered as a factor for changing the release rate of drug according to the intended application. The highest amount of release was observed in hydrogels with the highest amount of lignin, so that in the first two hours, its amount was about six times higher than that of pure chitosan hydrogel.

The formation of gall is one of the various types of vegetarianism, and gall producing insects cause stress in their hosts. The present study aimed to investigate the changes of some biochemical and photosynthetic indices due to the gall in Persian oak trees in Forests of Middle Zagros. Sampling was performed from trees infected by gall and healthy trees in Blouran forests. The results showed that the amount of lignin, proline and anthocyanin were increased significantly in infected trees compared to healthy trees (P≤0.01). Moreover, the indices of chlorophyll a, chlorophyll b, total chlorophyll and carotenoid content were decreased significantly in infected trees (P≤0.01). According to the results, it can be concluded that the presence of insects producing gall on Quercus branti trees is considered as a pest. The increasing presence of these insects and the consequent changes in trees declare the necessity of the control of the pest and the prevention of the creation of critical spots.

Litter decomposition process is a vital process in forest biogeochemical cycles that cause nutrient release in to the soil. Lignin degradation is considered the limiting step of litter decomposition. This research was done to study the Factors regulating litter mass loss in late decomposition stages, using Beech (Fagus orientalis lipsky), Alder (Alnus subcordata C.A.Meyer), Maple (Acer velutinum Boiss.) and Norway spruce (Picea abies (L) Karst) for 405 days at pure Norway spruce plantation using litterbag method in Lain Region. The finding of this study showed that litter decomposition of all litters significantly had a positive correlation with initial litter Nitrogen and Manganese concentrations (P

One of the solutions to increase the applications of lignin molecules is increasing reactive functional groups by chemical modification. Adding reactive functional groups into the lignin structures is one the best proposed methods. The aim of this study was to investigate change in structure as well as glass transition temperature (Tg) of Soda and Kraft lignins after hydroxymethylation them with non-volatile aldehyde entitle Glyoxal. Kraft and Soda black liquors were prepared from Choka and Pars Co, respectively. Lignins were extracted from black liquors by acidic method. Then changes in structure and thermal properties of the glyoxalated lignins were measured with Fourier transform infrared (FTIR) and differential scanning calorimetry (DSC) compared to pure lignins, respectively. The results indicated that glyoxalation increase reactive functional groups in lignins. Also FTIR result indicated that glyoxalation made some changes in lignin structure. DSC analysis showed that Tg of Soda and Kraft lignins reduced by glyoxalation. Finally DSC and FTIR analysis indicated that Soda lignin exhibited better potential for glyoxalation and have lower Tg compared to Kraft lignin.

In this study the results showed that aspen has less fiber length than horn beam and beech، fiber diameter and cell pit is more and cell wall thickness is less. Furthermore، the diameter of the imported birch fibers is of the most amount in the comparison of two types of beech and horen beam. The chemical component of aspen and birch wood flour consists of the least Klason lignin and the most holocellulose. The handsheet properties of CMP pulp of birch and aspen showed that the bursting strength and breaking length which is more than beech and horn beam.

Wet storage of bagasse is a common storage and preparation procedure in bagasse pulp and paper mills. Subsequently، for further elimination of pit and soluble materials، a washing process is applied. Even though this system seems simple، because of the presence of sugars in raw bagasse as well as deterioration of bagasse components during storage and the following washing، huge volumes، between 112-198 m3/hr.، of highly polluted effluent called bioliquor are generated. Pollution measurement shows that almost 2780 mg/liter BOD5، 5860 mg/liter total COD، 4200 mg/liter dissolved COD and 3900 mg/liter TDS is present in this effluent. The pH of the effluent varies between 5. 1 and 5. 3. The results of lignin and sugar measurements showed that، this effluent contains 995، 341، 101، 79، 76 and 21 mg/liter of lignin، glucose، arabinose، xylose، galactose، and mannose، respectively. The presence of lignin indicates the difficulty of the treatment. These pollutants deteriorate under anaerobic condition so that after 9 days under such condition and the temperature between 25 and 35ºC، BOD، COD، TDS، and color were reduced by 32. 7، 26، 29. 8 and 42. 8% of original values، respectively. Furthermore، these indices under the same conditions but after the duration of 30 days (model)، decreased about 75. 6، 66. 2، 70. 1 and 84. 2%، respectively.