The potential supply of biomass feedstocks in the US and Canada is estimated using a static supply function approach. Estimated total biomass available at a price of $100 per metric ton is 568 million metric tons in the US and 123 million tons in Canada, which together can displace 23-45 billion gallons of gasoline. Sufficient biomass, mainly agricultural and mill residues, will be available at prices of around $50/ton to meet the advanced biofuel mandates of the US Energy Independence and Security Act of 2007. The estimates of agricultural residue supply are very sensitive to the assumed fraction of residues that can be sustainably removed from the field, and the potential of municipal solid waste as a feedstock depends on which components can be economically converted into liquid biofuels.
Smoothness of paper surface is an important property of paper from its printability viewpoint. A number of techniques are available for characterizing the topographical features of paper surface. These techniques have led to the development of smoothness testers of various types such as air-leak testers, optical contact testers, surface profilers, and a number of ink and liquid application apparatus to assess the smoothness. While all these methods are intended to serve the same purpose, they differ so greatly in their basic approach that the agreement between them cannot be taken for granted. In the present work, these methods have been applied to characterize the surface of handsheets of mechanical pulps. A comparison of these methods reveals that different methods grade these pulps differently confirming the multidimensional nature of the surface structure
Streptomyces sp. PG-08-3 was isolated from the desert of Rajasthan (India). The organism produced mannanase (15 Umg-1 protein) in the presence of 0.5% guar gum as a sole carbon source in minimal media by submerged fermentation (SmF). Enzyme production was enhanced by 7.3-fold when 0.5% soyabean meal and 0.25% of leucine were added to the minimal media. Increasing the guar gum concentration in the media by 0.1-1.0% resulted in linearly enhanced the production of mannanase.
Autohydrolysis of Eucalyptus globulus was conducted at three different intensity levels typical for prehydrolysis kraft pulping as utilized for manufacturing dissolving pulp grades. The objective was to establish for the autohydrolysis process a detailed mass balance comprising the chemical composition of all three phases: the autohydrolysate, the released gas, and the solid residue. Carbohydrate determination involved both acid methanolysis combined with gas chromatography (GC) and sulfuric acid total hydrolysis with high performance anion exchange chromatography (HPAEC) coupled with pulsed amperometric detection (PAD); this allowed reliable quantification of neutral as well as acidic sugar units in cellulosic and non-cellulosic polysaccharides. Uronic acids present in the Eucalyptus globulus wood were progressively degraded through decarboxylation, leading to substantial carbon dioxide formation. The degree of acetylation of xylan remaining in the wood residue was clearly reduced, while the amount of bound acetyl groups in dissolved xylo-oligosaccharides (XOS) stayed relatively constant as a function of autohydrolysis intensity. The bulk of the lignin that was dissolved during autohydrolysis could be attributed to the acid-soluble lignin content of the wood. Only small amounts of Klason lignin were dissolved.
This study concerns the structural change of lignin during auto-catalyzed ethanol-water pulping of aspen by 1H-NMR. The results showed that the linkages of alkyl-aryl ether of lignin, such as the α-ether linkages (α-O-4) and the β-ether linkages (β-O-4), were broken and the alkyl part formed carbenium at the Cα and Cβ of the aliphatic branch. Meanwhile, the aryl part of ether accepted one H+ and formed phenol. Because of the electronegative effect originating from the electron cloud of phenyl, partial carbenium of Cβ was rearranged. Due to its ether or hydroxyl linkage, rearranging to Cβ, the Cα was changed into carbenium and formed a new β-O-4 alkyl-aryl ether. The β-O-4 alkyl-aryl ether was not stable and broken further. So the large molecule of lignin was disintegrated into a smaller one and dissolved into ethanol. Finally, the α+ carbenium reformed α-O-4 linkages of ether with phenol.
In an effort to devise inexpensive and sustainable production of ethanol fuel, experiments were conducted to establish conditions for Pichia stipitis NRRL Y-7124 to ferment a membrane treated wood hydrolysate derived from sugar maple to produce ethanol. The degree of aeration required to effectively utilize xylose, produce ethanol, and minimize xylitol formation as well as the optimal hydrolysate concentration were the conditions examined. P. stipitis produced the highest concentrations of ethanol in shake flasks at 150 rpm (14.3 g/L in 71 h), and 50% hydrolysate maximized ethanol yield (12.4 g/L in 51.5 h). In the 50% hydrolysate cultures, P. stipitis produced ethanol at a rate of 0.24 g/Lh with a yield of 0.41 g ethanol/g wood-derived carbohydrate.
A series of comparable specimens of hornbeam wood were submitted to fungal and chemical pretreatments. Two strains of erosive white-rot fungi (P. chrysosporium and T. versicolor) and a lignin-selective fungus C. subvermispora were used. Chemical pretreatments were carried out with diluted sodium hydroxide, or sodium hydroxide and then by hydrogen peroxide, or per-acetic acid. Both biotic and abiotic pre-treatments modified the chemical composition of wood and were accompanied by its weight loss. The applied fungi apparently delignified the specimens, however at the expense of cellulose, especially when the erosive strains of fungi were used. The chemical pretreatments caused deep deacetyl-ation, and milder delignification of wood and did not cause an apparent loss of cellulose. Biotic pretreatments of hornbeam wood, despite their marked delignification effect, led to unexpected increase in the contents of residual lignin in the resulting kraft pulps. On the other hand, pulping of the chemically pre-treated chips yielded pulps with low contents of residual lignin and much higher brightness.
An experimental study was conducted to determine the abrasive wear behaviour of different weight percentage bamboo powder filled polyester composites under the multipass mode. The effect of bamboo powder concentration and sliding distance on the weight loss of composites has been analyzed. Worn surface have been analyzed to observe the mechanism of wear. The weight loss depends on bamboo powder concentration. The weight loss decreases with the increase of sliding distance. Samples having 20 weight percentage (wt%) of bamboo powder show the maximum weight loss during abrasion.
Various hydrophilic polyelectrolytes, including cationic starch products, are used by papermakers to promote inter-fiber bonding and increase paper’s dry-strength. Thus, papermakers can meet customer require-ments with a lower net cost of materials, more recycled fibers, or higher mineral content. In the absence of polymeric additives, key mechanisms governing bond development between cellulosic fibers include capillary action, three-dimensional mixing of macromolecules on facing surfaces, conformability of the materials, and hydrogen bonding. Dry-strength additives need to adsorb efficiently onto fibers, have a hydrophilic character, and have a sufficiently high molecular mass. Though it is possible to achieve significant strength gains by optimal usage of individual polyelectrolytes, greater strength gains can be achieved by sequential addition of oppositely charged polyelectrolytes. Superior strength can be achieved by in-situ formation of polyelectrolyte com-plexes, followed by deposition of those complexes onto fiber surfaces. Polyampholytes also hold promise as efficient dry-strength additives. Opportunities for further increases in performance of dry-strength agents may involve fiber surface modification, self-assembled layers, and optimization of the dry film characteristics of dry-strength polymers or systems of polymers.
We have developed a semi-empirical model to relate the tensile energy absorption (TEA) of paper sheets formed from high-consistency refined pulp to pulp properties, including water retention value (WRV), fibre length, and fibre curl. TEA is shown to be related to the normalized stretch (ratio of stretch to tensile strength) and the tensile strength of the pulp. Normalized stretch appears to be a function of fibre curl, whereas tensile strength for a given pulp is a function of the fibre length, fibre curl, and WRV. The manner in which these three pulp properties develop in a given refining operation determines the development of TEA.
Carboxylation of cotton linters was investigated relative to its use in ion exchange. The effects of different treatments of cotton linters, such as alkali, acid, and activating agents, e.g. LiCl, on the molecular structure and carboxylation of cotton linters were taken in our consideration. The absence or presence of a crosslinking was considered, and the efficiency of these prepared carboxylated cotton linters toward metal ions uptake, as well as thermal analysis of treated and carboxylated cotton linters, was investigated. It was found that treatment of cotton linters with alkali and activating agent decreased the crystallinity index (band intensity at 1425/band intensity at 890 cm-1). On the other hand, the prepared carboxylated cotton linters had lower crystallinity index than uncarboxylated linters. Thermal analysis of the treated and carboxylated cotton linters allowed calculation of the activation energy of thermally treated materials. It was found that the crosslinked and acid treated cotton linters had a higher activation.
Cellulose fibres from sugarcane bagasse were bleached and modified by zirconium oxychloride in order to improve the mechanical properties of composites with high density polyethylene (HDPE). The mechanical properties of the composites prepared from chemically modified cellulose fibres were found to increase compared to those of bleached fibres. Tensile strengths of the composites showed a decreasing trend with increasing filler content. However, the values for the chemically modified cellulose fibres/HDPE composites at all mixing ratios were found to be higher than that of neat HDPE. Results of water immersion tests showed that the water absorption affected the mechanical properties. The fracture surfaces of the composites were recorded using scanning electron microscopy (SEM). The SEM micrographs revealed that interfacial bonding between the modified filler and the matrix was significantly improved by the fibre modification.
Near infrared (NIR) spectroscopy method was introduced to measure the lignin content in Acacia species. Acid-soluble lignin, Klason lignin, and total lignin contents from 78 wood meal samples of Acacia spp. trees grown in Guangxi province with different ages, height, and families were measured by wet chemistry. NIR spectra were also collected using a Bruker MPA spectrometer within 4000-12500cm-1 of wavenumbers using a standard sample cup and split into calibration and prediction sets. Equations were developed using partial least squares (PLS) regression and cross validation for multivariate calibration in this study. High coefficients of determination (R2) and low root mean square errors of cross-validation (RMSECV) were obtained for Klason lignin (R2=0.94, RMSECV=0.398), acid-soluble lignin (R2=0.87, RMSECV=0.144), and total lignin (R2=0.91, RMSECV=0.448) from wood meal. High correlation coefficients were found between laboratory and predicted values for Klason lignin, acid-soluble lignin, and total lignin contents, with R2 and RMSEP values ranging from 0.67 to 0.94, and 0.19 to 0.526, respectively. The study showed that NIR analysis can be reliably used to predict lignin content in Acacia spp.
Bio-oil is a promising alternative source of energy produced from fast pyrolysis of biomass. Increasing the viscosity of bio-oil during storage is a major problem that can be controlled by the addition of methanol or other alcohols. This paper reports the results of our investigation of the reactions of short chain alcohols with aldehydes and acids in bio-oil. The reaction of methanol with hydroxyacetaldehyde (HA) to form the acetal was catalyzed by the addition of 7 x 10-4 M strong acids such as sulfuric, hydrochloric, p-toluene sulfonic acid, and methanesulfonic acid. HA formed 2,2-dimethoxyethanol (DME), and at 60 oC the equilibrium was reached in less than one hour. Smaller amounts of DME were formed in the absence of strong acid. HA, acetaldehyde, and propanal formed their corresponding acetals when reacted with methanol, ethanol, 1-propanol or 1-butanol. Esters of acetic acid and hydroxyacetic acid were observed from reactions with these same four alcohols. Other acetals and esters were observed by GC/MS analysis of the reaction products. The results from accelerated aging experiments at 90 oC suggest that the presence of methanol slows polymerization by formation of acetals and esters from low molecular weight aldehydes and organic acids.
The accessibility of cellulose samples having various degrees of crystallinity was studied with respect to molecules of water, lower primary alcohols, and lower organic acids. It was found that small water molecules have full access to non-crystalline domains of cellulose (accessibility coefficient α = 1). Molecules of the lowest polar organic liquids (methanol, ethanol, and formic acid) have partial access into the non-crystalline domains (α<1), and with increasing diameter of the organic molecules their accessibility to cellulose structure decreases. Accessibility of cellulose samples to molecules of various substances is a linear function of the coefficient α and the content of non-crystalline domains. The relationship between crystallinity (X) and accessibility (A) of cellulose to molecules of some liquids has been established as A = α (1-X). The water molecules were found to have greater access to cellulose samples than the molecules of the investigated organic liquids. The obtained results permit use of accessibility data to estimate the crystallinity of cellulose, to examine the structural state of non-crystalline domains, and to predict the reactivity of cellulose samples toward some reagents.
The “near neutral hemicellulose extraction process” involves extraction of hemicellulose using green liquor prior to kraft pulping. Ancillary unit operations include hydrolysis of the extracted carbohydrates using sulfuric acid, removal of extracted lignin, liquid-liquid extraction of acetic acid, liming followed by separation of gypsum, fermentation of C5 and C6 sugars, and upgrading the acetic acid and ethanol products by distillation. The process described here is a variant of the “near neutral hemicellulose extraction process” that uses the minimal amount of green liquor to maximize sugar production while still maintaining the strength quality of the final kraft pulp. Production rates vary between 2.4 to 6.6 million gallons per year of acetic acid and 1.0 and 5.6 million gallons per year of ethanol, depending upon the pulp production rate. The discounted cash flow rate of return for the process is a strong function of plant size, and the capital investment depends on the complexity of the process. For a 1,000 ton per day pulp mill, the production cost for ethanol was estimated to vary between $1.63 and $2.07/gallon, and for acetic acid between $1.98 and $2.75 per gallon depending upon the capital equipment requirements for the new process. To make the process economically attractive, for smaller mill sizes the processing must be simplified to facilitate reductions in capital cost.
A formic/acetic acid/water system was used in the ratios of 30:60:10, 20:60:20, and 30:50:20 separately for efficient hydrolysis and bioconversion of poplar chips, under the solid/liquid ratio of 1:12(g/ml), at 105 oC for 30, 45, 60, 75, and 90 min, respectively. The highest yield of 69.89% was at a formic/acetic acid /water ratio of 30:50:20(v/v/v), with solid/liquid in the ratio of 1:12(g/ml) at 105 oC for 90min. Lower kappa number and similar yield were achieved when hydrolytic residual woodchips were used for kraft pulping with over 2% Na2O and temperature 5 °C lower compared to untreated chips. Pulps from prehydrolysis-treated chips were easy to beat. But the tensile index, tear index, and burst index of the handsheets obtained from pulp with lowest kappa number from prehydrolysis-treated poplar chips were lower than those of the pulp from the untreated chips. Considerable xylose could be obtained from the prehydrolysis stage following kraft pulping under the same conditions for prehydrolysis-treated chips and untreated chips. However, by building on the mature kraft pulping and xylitol processes, large amounts of xylose from the hemicellulose were obtained in prehydrolysis, allowing production of high-valued products via biorefinery pathways. An economical balance of chemical dosage, energy consumption, pulp properties, and xylose value for prehydrolysis with organic acid should be reached with further investigation.
Bio-oil produced from fast pyrolysis of biomass contains various levels of acetic and formic acids derived from breakdown of cellulose and hemi-cellulose components. Removal of these organic acids from bio-oil was investigated for use as industrial chemicals as well as to improve the quality of recovered bio-oil as fuel in various applications. Calcium oxide and a quaternary ammonium anion-exchange resin were used to form acid salts of the organic acids, which were then separated, and the organic acids were generated by reacting with sulfuric acid. Both methods were found to be effective in limited ways and various difficulties encountered in this approach are discussed.
To enhance the bleaching efficiency, the activator of tetra acetyl ethylene diamine (TAED) was used in conventional H2O2 bleaching. The H2O2/TAED bleaching system can accelerate the reaction rate and shorten bleaching time at relative low temperature, which can reduce the production cost. In this research, the process with hydrogen peroxide activated by TAED bleaching of Populus nigra chemi-thermo mechanical pulp was optimized. Suitable bleaching conditions were confirmed as follows: pulp consistency 10%, bleaching temperature 70oC, bleaching time 60 min when the charge of H2O2 was 4%, NaOH charge 2%, and molar ratio of TAED to H2O2 0.3. The pulp brightness gain reached 23.6% ISO with the optimized bleaching conditions. FTIR analysis indicated that the H2O2/TAED bleaching system can decrease carbonyl group further than that of conventional H2O2 bleaching, which contributed to the higher bleaching efficiency and final brightness. The H2O2/TAED bleaching had stronger oxidation ability on lignin than that of H2O2 bleaching.
Flax fibre reinforced polypropylene composites were fabricated using a high speed mixer followed by injection moulding. Prior to composite production, the fibre was modified by acetylation in the presence of perchloric acid. The effect of acetylation of the fibre was assessed on the basis of moisture resistance and dielectric properties of the resulting composites. It was found that the moisture absorption and swelling properties of the composites were reduced respectively by 60% and 30% due to acetylation. Two different types of biocide were mixed with untreated flax fibre, and the samples were exposed to decay fungi for up to 3 months along with control polypropylene. The composites with acetylated fibres showed good protection against fungi, and biocide had less effect on biological resistance. The dielectric properties of the flax-polypropylene composites were also estimated as a function of aging period. The composites with modified fibre showed more improvement in dielectric properties compared to the composites with untreated fibres. The mechanical properties were investigated for those composites. Tensile and flexural strengths of composites were found to be increased following acetylation due to modification, and strength properties of both untreated and acetylated flax fibre reinforced polypropylene composites decreased with respect to aging period. The Charpy impact strengths of composites were found to increase with increasing aging periods.
The characteristics of enzymatic/mild acidolysis lignin (EMAL) isolated from moso bamboo were investigated using pyrolysis-gas chromato-graphy/mass spectrometry (Py-GC/MS). Pyrolysis temperature as a factor on products was studied, and the pyrolysis mechanism was inferred with respect to the dominating products. Research results showed that pyrolysis products derived from EMAL pyrolysis were mainly heterocyclic (2,3-dihydrobenzofuran), phenols, esters, and a minor amount of acetic acid. Pyrolysis temperature had a distinct impact on yields of pyrolysis products. As pyrolysis temperature increased, the yield of 2,3-dihydrobenzofuran rapidly decreased; however, yields of phenols increased smoothly. It can be obtained that, at the low temperatures (250-400oC), pyrolysis products were mainly 2,3-dihydrobenzofuran, and the highest yield was 66.26% at 320oC; at the high temperatures (400-800oC), pyrolysis products were mainly phenols, and yields hit their highest level of 56.43% at 600 oC. A minor amount of acetic acid only emerged at 800°C. Knowledge of pyrolysis products releasing from EMAL and the pyrolysis mechanism could be basic and essential to the understanding of thermochemical conversion of EMAL to chemicals or high-grade energy.
Pectins are important structural elements in spruce fibres. Alkaline peroxide bleaching of spruce thermomechanical pulp (TMP) causes degradation and demethylation of pectins, yielding high-charge-density pectic acids. The pectic acids in fibres contribute strongly to the negative fibre charge, and the dissolved pectic acids increase the cationic demand of bleached TMP water. In this study, a method to isolate pectic acids from peroxide-bleached TMP pulp water is presented. The pectic acids were isolated and purified in good yield using a polyacrylate resin to remove lignin, a cellulose filter to remove galactoglucomannans (GGM), and an anion exchange resin to separate pectic acids from neutral carbohydrates. Salts and residual low-molar-mass carbohydrates were further removed from the isolated pectic acids by dialysis. The isolated pectic acids (>80% purity) had a low molar mass and a wide polydispersity (5.9 kDa, MW/MN 3.3). The aggregation and precipitation of the isolated pectic acids, as well as citrus fruit pectic acids with well-defined molar masses, by Ca2+-ions were studied. The molar mass of pectic acids was a key factor determining the precipitation of Ca2+-pectates. Pectic acids below 6 kDa were not precipitated by Ca2+, while higher molar masses led first to partial and then to complete precipitation. The precipitated Ca2+-pectates may impair paper machine runnability and paper quality.
The applicability of a special pilot-scale installation (Short Circulation Device) was studied for demonstrating the enrichment of selected resin and fatty acids in process waters when increasing water reuse during the manufacture of paper. The traditional gas chromatography with flame ionization detection (GC-FID), turbidity, and online sample enrichment (solid phase extraction, SPE) for atmospheric pressure chemical ionization-mass spectrometry (APCI-MS) measurements were used for the analysis of the resin and fatty acids. The data from all the measurements with unbleached thermomechanical pulp (TMP) process waters were in a good agreement, and correlation coefficients (R2) > 0.9 were obtained in each case. Rapid information about the levels of wood extractives in papermaking process waters is of great importance, and it offers a suitable way to predict oncoming pitch problems. It was concluded that the routine control of the extractives level in papermaking process waters is possible by all these methods.
Defining and quantifying amino acid requirements will become an important consideration in the next generation of feeding schemes for dairy cattle beyond the current emphasis on identification of limiting amino acids. In this context different amino acid profiles of untreated, urea treated, fungal treated, and urea plus fungal treated lignocellulosic feed by both P. ostreatus wild and its two cellulase-minus/ less lignolytic mutants were analyzed. Cellulase-free mutant strains were obtained after 20 minutes of exposure to UV light and 0.4 seconds to X-rays. A UV mutant of P. ostreatus (POM1) exhibited better performance than the X-ray mutant (POM2) in terms of production of less cellulolytic and more lignolytic enzymes. Urea treatment of straw enhanced the total amino acid content by less than a factor of two, while the fungal treatment improved it by 13-14 times. Fungal treatment of urea-treated straw improved the total amino acid content by a factor of 15, indicating the importance of urea in the straw. Further, the fungal treatment of urea-treated straw enhanced the quantity of amino acids such as glutamine, glycine, aspergine, etc. by 15-20 times. The quantity of limiting amino acids such as methionine, lysine, and histidine was also enhanced by 8 to 10 times through the fungal treatment. Maximum amounts of all the amino acids were found in urea plus fungal (POM1) treated paddy straw than in only fungal treated and only urea treated paddy straws.
The graft copolymerization of acrylamide, N-vinyl-2-pyrralidone and N, N’-methylene-bis-acrylamide was carried out to modify the sisal fiber to improve its mechanical and thermal stability. The grafting of poly-(acrylamide-co-N-vinyl-2-pyrrolidone) on sisal fiber surfaces facilitated the loading of Ag(I) ions and Ag(0) nanoparticles. Surface microstructure of the surface modified sisal fiber confirmed the grafting of the copolymer. The XRD and FTIR graphs also showed changes on grafting and on Ag(I) ions and the loading of Ag(0) nanoparticles. It is evident from the DSC curves that the initial thermal stability was improved by delaying the hemicellulose decomposition on grafting and silver ion loading.
This paper describes the preparation of chemically modified oil palm empty fruit bunch (OPEFB) with hydroxamic acid functional group and its use for the sorption of Cu(II) from aqueous solution. OPEFB was grafted with poly(methylacrylate) (PMA), using H2O2/Fe2+ as initiator. The PMA grafted OPEFB (PMA-OPEFB) was treated with hydroxylammonium chloride in alkaline medium to produce hydroxamic acid grafted fiber (PHA-OPEFB). The FTIR spectrum of OPEFB grafted with PMA showed an intense absorption band at 1734 cm-1 which is attributed to C=O vibration in the grafted ester. After hydroxylamine treatment, the intensity of absorption band at 1734 cm-1 decreased and new bands appeared at the 1640 cm-1 related to C=O vibration in hydroxamic acid and at the 1568 cm-1 related to the N-H amide. Sorption of Cu(II) by PHA-OPEFB was effective over a pH range of 4 to 6. The sorption followed the Langmuir model with maximum capacities of 74.1 mg g-1 at 25 °C. The sorption process was exothermic, as shown by the negative value of enthalpy change, H. The free energy change (G) for the sorption was negative, showing that the sorption process was spontaneous. A kinetic study showed that the Cu(II) sorption followed a second order kinetic model.
A series of experiments were carried out to investigate photo-degradation of thermally modified (at 210oC and minus 0.9 bars for two hours) and non-modified spruce wood [Picea abies L (Karst)], coated with transparent and semitransparent (with 3% pigment content) acrylic coatings during artificial UV light irradiation for 200 hours. Photo-degradation was evaluated in terms of colour changes throughout the irradiation period at an interval of 50 hours, along with IR and EPR spectroscopic study. One set of modified and non-modified woods was painted with coatings, while the other set was covered with free films made of coatings, just to simulate coated wood. The colour changes for both modified and non-modified wood samples without paint-coat or free film cover were comparable to that of wood samples with paint-coat and free film cover for transparent coat type, which indicated its ineffective-ness to prevent photo-degradation of wood underneath. However, the colour changes for both modified and non-modified wood samples with paint-coat and free film cover were much lower than those of samples without paint-coat or free film cover for semitransparent coat type, which might be due to hindrance of transmission of light energy through pigment to reach the underlying wood surface. On the other hand, whole substrate-coating system showed better photo-stability, when thermally modified wood was used as substrate. However, the colour changes of paint-coated and free-film covered samples for both modified and non modified woods might be due to colour changes of wood specimen underneath, because free films of both the coat types showed negligible colour change during UV irradiation.
Specific and strong cellulose-binding characteristics were utilized for promoting retention of additives in contaminated papermaking systems. Cellulose-binding domain (CBD) of cellulase derived from Trichoderma viride was separated by digestion with papain, and then introduced into anionic polyacrylamide (A-PAM) through a condensation reaction using water-soluble carbodiimide. The CBD-modified A-PAM (CBD-A-PAM) showed good retention on pulp fibers, resulting in high tensile strength paper sheets. The effect remained almost unchanged in the presence of model interfering substances such as ligninsulfonate and Ca2+ ions, whereas commercial cationic paper-strengthening polymer became ineffective. The cellulose-binding force of CBD was quantitatively determined by atomic force microscopy (AFM) in the liquid state. Histidine-tagged CBD protein was obtained using Escherichia coli via an expression of CBD derived from Cellulomonas fimi, and immobilized on a gold-coated AFM probe. A strong attractive force was detected only at a CBD/cellulose interface, even when Ca2+ ions were present in high concentration. Direct estimation of CBD affinity for cellulose substrate by AFM would provide significant information on the interfacial interactions useful for the functional design of papermaking additives.
The use of low-cost, locally available, highly efficient, and eco-friendly adsorbents has been investigated as an ideal alternative to the current expensive methods of removing dyes from wastewater. This study investigates the potential use of activated carbon prepared from the peel of Cucumis sativa fruit for the removal of methylene blue (MB) dye from simulated wastewater. The effects of different system variables, adsorbent dosage, initial dye concentration, pH, and contact time were investigated, and optimal experimental conditions were ascertained. The results showed that as the amount of the adsorbent increased, the percentage of dye removal increased accordingly. The optimum pH for dye adsorption was 6.0. Maximum dye was sequestered within 50 min of the start of each experiment. The adsorption of methylene blue followed the pseudo-second-order rate equation and fit the Langmuir, Freundlich, Dubinin-Radushekevich (D-R), and Tempkin equations well. Maximum removal of MB was obtained at pH 6 as 99.79% for adsorbent doses of 0.6 g/ 50 mL and 25 mg/L initial dye concentrations at room temperature. The maximum adsorption capacity obtained from the Langmuir equation was 46.73 mg g-1. The rate of adsorption was found to conform to pseudo-second-order kinetics with a good correlation (R2 > 0.9677) with intraparticle diffusion as one of the rate-determining steps. Activated carbon developed from the peel of Cucumis sativa fruit can be an attractive option for dye removal from wastewater.
The effects of thermo-compression on the physical properties such as bulk density, mass yield, surface area, and also adsorption capacity of activated carbon were studied. The activated carbon samples were prepared from thermo-compressed and virgin fir-wood by two methods, a physical activation with CO2 and a chemical activation with KOH. A preliminary thermo-compression method seems an easy way to confer to a tender wood a bulk density almost three times larger than its initial density. Thermo-compression increased yield regardless of the mode of activation. The physical activation caused structural alteration, which enhanced the enlargement of micropores and even their degradation, leading to the formation of mesopores. Chemical activation conferred to activated carbon a heterogeneous and exclusively microporous nature. Moreover, when coupled to chemical activation, thermo-compression resulted in a satisfactory yield (23%), a high surface area (>1700 m2.g-1), and a good adsorption capacity for two model pollutants in aqueous solution: methylene blue and phenol. Activated carbon prepared from thermo-compressed wood exhibited a higher adsorption capacity for both the pollutants than did a commercial activated carbon.
Peat with an approximate 60% carbon content collected in the suburbs of Palangka Raya, Indonesia, was carbonized, followed by activation with steam in an electric furnace. The resultant activated carbon (AC) had ca. 900 m2/g of BET surface area and 1000 mg/g of iodine adsorption. This performance implies that this AC can be used as an adsorbent for environmental purification. We had a carbonizing furnace manufactured in Palangka Raya, which did not require electric power. Some AC having 350 mg/g of iodine adsorption was obtained by using this furnace. Although the adsorption ability was much lower than that of commercially available AC, the AC achieved significant decoloration and decrease in chemical oxygen demand of polluted river water. Thus, this article demonstrated the potential of tropical peat soil as a source of AC.
Activated lignin having a surface area of 1023 m2 g-1 has been prepared from sulfate lignin that was treated by 30% H2O2 and carbonized at 300 °C in order to test the chromium (VI) adsorption from aqueous solution. The influence of contact time, pH, initial concentrations of adsorbent and adsorbate, and temperature on the adsorption capacity were investi-gated. The maximum removal of Cr(VI) was found to be 92.36 % at pH=2 and a contact time of 80 min. Optimal concentration of lignin and Cr(VI) were found to be 3.8 g L-1 and 180 mg L-1, respectively. The adsorption kinetics data fitted well with a pseudo-second-order equation, and the rate of removal of chromium was found to speed up with increasing temperature. Activation energy for the adsorption process was found to be 18.19 kJ mol-1. The Langmuir and Freundlich adsorption isotherm models were applied to describe the isotherm and isotherm constants for the adsorption of Cr (VI) on lignin. These constants and correlation coefficients of the isotherm models were calculated and compared. Results indicated that Cr (VI) uptake could be described by the Langmuir adsorption model. The maximum adsorption capacity (qm) of Cr (VI) on lignin was 75.75 mg g-1 at 40°C. The dimensionless equilibrium parameter (RL) signified a favorable adsorption of Cr (VI) on lignin and was found to be between 0.0601 and 0.818 (0<RL<1). The thermodynamic parameters such as ΔG°, ΔS°, and ΔH° were calculated, and it was found that the reaction was spontaneous and endothermic in nature. This study indicates that lignin has the potential to become an effective and economical adsorbent for removal Cr (VI) from waste water.
Experiments were performed to evaluate a recent extraction process called the instantaneous controlled pressure drop process (briefly: DIC process: “Détente Instantanée Contrôlée”) for extracting some volatile compounds from red cedar wood. This process involves subjecting red cedar chips for a short time (30 s to 5 min) under a steam pressure (1 to 6 bars or from 100 to 165 °C). This first step is followed by a flash decompression toward vacuum (up to 50 mbar). This transition induces a fast evaporation of water and volatile compounds and a cooling effect. The effects of two processing parameters (steam pressure and heating time) on the total extraction yield and on yield of four volatile compounds were evaluated by response surface methodology. The results indicated that the processing pressure is the predominant parameter for global extraction yield of oil (E.O= Extracted Oil) and for yield of the four compounds investigated in this study. The processing time is also a significant parameter but less than processing pressure. Moreover, activated carbon produced from DIC-treated residue revealed larger pore sizes compared to untreated samples.
Bonding and activation in paper were studied with the help of laboratory test sheets and common paper strength tests. Different papermaking furnishes and raw material treatments were used to examine the effects they have on bonding and activation. Furthermore, various boundary conditions during drying were included to single out the influence of bonding and activation on paper properties. It was found that bonding is clearly increased by beating of kraft pulp, starch addition, and thermomechanical pulp fines, whereas activation benefited most from beating and addition of reinforcement fibers to mechanical pulp based furnishes. Subjecting test sheets to increasing amounts of drying stress affected activation positively, and bonding negatively. The increase in activation did not seem to be dependent on the beating degree of chemical pulp fibers. Bonding, on the other hand, deteriorated more significantly in sheets made of extensively beaten kraft fibers, i.e. in sheets where the initial bonding potential was higher. Commonly used paper strength measurements provide dependable and accurate tools for assessing the effect of different variables on both bonding and activation. A short literature survey of bonding and activation is also provided.
Dhaincha (Sesbania aculeata) is one of the annual plants in Bangladesh that has potential as a fiber source. It is a crop generally cultivated for its nutritive value to soil. This paper describes the effect of harvesting age of dhaincha on chemical, morphological, pulp, and papermaking properties and its bleachability. Dhaincha is a short length fiber that can be used as a substitute to hardwood. Fiber length was found to increase slightly with increasing age of the plant. The alpha-cellulose content in dhaincha increased and pentosan decreased with increasing age. Dhaincha pulp was prepared from 2, 3, 4, 5, and 6 month old plants under identical cooking conditions. Pulp yield (43-45 %) and kappa number (26-30) did not follow direct correlation with plant age. But physical properties of unbleached pulp increased linearly with the increase of age. Bleachability of dhaincha pulp was quite poor. The bleachability of pulp was improved when the age of dhaincha was increased.
The effects of several non-ionic commercial surfactants and their dosage on soda pulping and ECF bleaching of soda and soda-surfactant pulps of bagasse were investigated. The properties of bleachable pulps obtained with conventional soda and with soda-surfactants were studied and compared. The results showed application of surfactants during the soda pulping of bagasse decreased kappa number and improved the yield and brightness of resulting pulp. Using the surfactants reduced alkali consumption during pulping. The bleaching experiments showed that the pulps obtained with the three types of applied surfactants namely, ELA-2, FAE-20, and PEG1000 could be easily bleached with D0ED1 or D0EpD1 sequences. The addition of most used surfactants in soda pulping of bagasse led to higher brightness in comparison to reference pulp with the same bleaching sequence. Strength properties of bleached pulps obtained with surfactants were higher than the pulp obtained with conventional soda pulping.
Desmodur VTKA and Urea formaldehyde) on wooden materials (Scotch pine and oriental beech) cut tangentially and radially impregnated with Tanalith-C, creosote, and sodium silicate in layer (3, 4, 5) of laminated veneer lumber (LVLs) on thermal conductivity. The lowest thermal conductivity of 0.103 Kcal/mh°C was obtained in Scotch pine, cut tangentially, impregnated with creosote, bonded with urea formaldehyde, and 3 layer LVL. The highest thermal conductivity of 0.185 Kcal/mh°C was obtained in oriental beech, cut radially, impregnated with Tanalith-C, bonded with PVAc, and 5 layers LVL. Consequently, oriental beech wood cut radially and impregnated with Tanalith-C, bonded with PVAc adhesive and 5 layers in LVL can be used as a material in construction where the thermal conductivity is required. Scotch pine wood cut tangentially and impregnated with creosote, bonded with urea formaldehyde adhesive and 3 layers in LVL can be used as a material in construction where the insulation is required.
Composite materials and wooden dowels are being used increasingly in the construction of furniture frames and inner decoration. Yet there is little information available concerning the withdrawal strength of various fasteners, and, in particular, dowels in composite materials edged solid wood edge bandings. The aim of this study was to determine the withdrawal strengths of 6, 8, 10 mm diameter dowels produced from beech with respect to edge of a medium-density fiberboard (MDF) or particleboard (PB) edged with 5, 10 and 15 mm thickness of solid wood edge banding of uludag fir, bonded with different adhesives. According to TS 4539 standard, the effects of edge banding thickness, dimension of dowels, type of composite materials and type of adhesives used for edge banding on the withdrawal strength were determined. The highest (6.37 N/mm²) withdrawal strength was obtained in beech dowels with 8 mm diameter for MDF with 5 mm thickness of solid wood edge banding of uludag fir bonded with D-VTKA adhesive. According to results, if the hole wall and the surface of dowel are smooth then the adhesives give better mechanical adhesion with dowels and composite materials.
The goal of this study was to determine the effects of different joint angles and adhesives on diagonal tension performances of the box-type furniture made from solid wood and medium density fiberboard (MDF). After drilling joints of 75º, 78º, 81º, 84º, and 87º degrees on Oriental beech, European oak, Scotch pine, and MDF samples, a diagonal tensile test was applied on corners glued with polyvinyl acetate (PVAc) and polyurethane (D-VTKA = Desmodur-Vinyl Trieketonol Acetate) according to ASTM D 1037 standard. With reference to the obtained results, the highest tensile strength was obtained in European oak with PVAc glue and joint angle of 84º, while the lowest value was obtained in MDF with D-VTKA glue and joint angle of 75º. Considering the interaction of wood, adhesive, and joint angle, the highest tensile strength was obtained in European oak with joint angle of 81º and D-VTKA glue (1.089 N.mm-2), whereas the lowest tensile strength was determined in MDF with joint angle of 75º and PVAc glue (0.163 N.mm-2). Therefore, PVAc as glue and 81º as joint angle could be suggested to obtain some advantageous on the dovetail joint process for box-type furniture made from both solid wood and MDF.
The aim of this study was to evaluate the effect of heat treatment on the shear strength of tali (Erythrophleum ivorense) and iroko (Chlorophora excelsa) woods, bonded with some structural adhesives. Shear strength of untreated and heat-treated woods bonded with phenol-formaldehyde (PF), melamine-urea-formaldehyde (MUF), melamine-formaldehyde (MF), and polyurethane (PUR) adhesives was studied. An industrial heat treatment method (ThermoWood) was used. The timbers were thermally modified for 2 hours at 180 ºC. Laminated samples having two sample sets were prepared from untreated and heat-treated wood for the shear strength test. The results of the tests showed that the heat treatment affected shear strength of laminated wood negatively. Although there was a considerable difference in adhesive bond shear strength between untreated and treated wood, both wood species bonded with the adhesives fulfilled the required value for shear strength of the adhesive bonds. PF, MUF, MF, and PUR adhesives performed in a rather similar way for both wood species.
The present work concerns the experimental evaluation of hazelnut shells as a low cost natural biosorbent. Adsorption of the direct azo dye Congo Red was performed within a concentrations range of 50-5000 mg/L. Hazelnut shells were employed as organic support for Phanerochaete chrysosporium cultures to study the best cultural medium composition for the MnP production. The capability of Phanerochaete chrysosporium to take macronutrients as carbon and nitrogen from hazelnut shells was demonstrated. Cultures of Phanerochaete chrysosporium were carried out with hazelnut shells coming from Congo Red adsorption tests, showing that 43% of the adsorbed dye was degraded.
Bark flour from ponderosa pine (Pinus ponderosa) was consolidated into pellets using citric acid as cross-linking agent. The pellets were evaluated for removal of toxic heavy metals from synthetic aqueous solutions. When soaked in water, pellets did not leach tannins, and they showed high adsorption capacity for Cu(II), Zn(II), Cd(II), and Ni(II) under both equilibrium and dynamic adsorption conditions. The experimental data for Cd(II) and Zn(II) showed a better fit to the Langmuir than to the Freundlich isotherm. The Cu(II) data best fit the Freundlich isotherm, and the Ni(II) data fitted both Freundlich and Langmuir isotherms equally. According to the Freundlich constant KF, adsorption capacity of pelletized bark for the metal ions in aqueous solution, pH 5.1 ± 0.2, followed the order Cd(II) > Cu(II) > Zn(II) >> Ni(II); according to the Langmuir constant b, adsorption affinity followed the order Cd(II) >> Cu(II) ≈ Zn(II) >> Ni(II). Although data from dynamic column adsorption experiments did not show a good fit to the Thomas kinetic adsorption model, estimates of sorption affinity series of the metal ions on pelletized bark derived from this model were not consistent with the series derived from the Langmuir or Freundlich isotherms and followed the order Cu(II) > Zn(II) ≈ Cd(II) > Ni(II). According to the Thomas kinetic model, the theoretical maximum amounts of metal that can be sorbed on the pelletized bark in a column at influent concentration of ≈10 mg/L and flow rate = 5 mL/min were estimated to be 57, 53, 50, and 27 mg/g for copper, zinc, cadmium, and nickel, respectively. This study demonstrated the potential for converting low-cost bark residues to value-added sorbents using starting materials and chemicals derived from renewable resources. These sorbents can be applied in the removal of toxic heavy metals from waste streams with heavy metal ion concentrations of up to 100 mg/L in the case of Cu(II).
The adsorption of Trametes hirsuta and Melanocarpus albomyces laccases on cellulose and lignin model substrates was studied by quartz crystal microbalance with dissipation, QCM-D. The laccase-treated surfaces were also analyzed by atomic force microscopy (AFM) and x-ray photoelectron spectroscopy (XPS). The laccases were found to adsorb at acidic and neutral pHs on both surfaces. The adsorbed amounts increased rather linearly with the change in dissipation when the lignin or cellulose was treated with T. hirsuta laccase. Higher adsorbed amounts were obtained using M. albomyces laccase. The adsorption of M. albomyces laccase on lignin was strongly dependent on pH. At low pH thin and rigid laccase layers were formed and the amount adsorbed was high, while at high pH the laccase layers formed were dissipative and loose and the amount adsorbed was low. A good correlation between the adsorbed amount of laccase and the surface nitrogen content was found. The adsorption of laccases made the surface structure of the cellulose and lignin substrates more granular.
Polymer adsorption on cellulose nanofibrils and the effect on nanofibril water binding capacity were studied using cellulose nanofibril films together with quartz crystal microbalance with dissipation (QCM-D) and surface plasmon resonance (SPR). The experiments were performed in the immersed state, and special attention was paid to the effect of polymer properties on the water content and viscoelastic properties of the polymer/fibril layer. The dry mass of the adsorbed polymers was determined using SPR. The type of the adsorbed polymer strongly affected the water content and viscoelastic properties of the nanofibril film. The adsorption of a highly charged flocculating polymer, PDADMAC, caused dehydration of the film, which was also detected as nanofibril film stiffening. The adsorption of xyloglucan introduced a dispersing effect to the nanofibril film, which was detected as a loosening and softening of the nanofibril/polymer layer. A dispersing effect was also achieved with carboxymethyl cellulose (CMC), but CMC did not adsorb irreversibly on the nanofibril surfaces. In addition to the nanofibril film studies, the effect of polymer adsorption on cellulose nanofibril suspension aggregation was demonstrated using confocal laser scanning microscopy (CLSM). Xyloglucan was shown to open the nanofibril aggregate structures and act as a dispersing agent, whereas the other polymers studied did not have as significant an effect on aggregation.
Cellobiose-pendant polymers were synthesized by radical polymerization and their affinity for a cellulose matrix was investigated by quartz crystal microbalance (QCM). A 2-(methacryloyloxy)ethylureido cellobiose (MOU-Cel) macromer was synthesized by coupling cellobiosylamine with 2-(methacryloyloxy)ethyl isocyanate followed by polymerization in an aqueous radical reaction system. The interaction of the resulting poly(MOU-Cel) with a pure cellulose matrix in water was evaluated by QCM analysis. Poly(MOU-Cel) was strongly adsorbed to the cellulose substrate, whereas neither cellobiose nor MOU-Cel macromer exhibited an attractive interaction with cellulose. This specific interaction was not inhibited by the presence of ionic contaminants, suggesting that multiple cellobiopyranose moieties in each polymer molecule might cooperatively enhance its affinity for cellulose. Moderate insertion of acrylamide units into the polymer backbone improved the affinity for cellulose, possibly due to an increased mobility of sugar side chains. Polymers such as these, with a high affinity for cellulose, have potential applications for the surface functionalization of cellulose-based materials, including paper products.
Batch adsorption studies were undertaken with the abundantly available waste biosorbent Tectona grandis L.f. leaf powder for removal of cadmium(II) from aqueous solutions. The adsorption experiments were performed under various conditions such as time, temperature, different initial Cd(II) concentrations, pH, adsorbent dosage, and adsorbent particle size. The data showed that in 30 minutes, 1 g of Tectona grandis L.f. could remove 86.73% of cadmium(II) from 50 mL aqueous solution containing 100 mg L-1 of Cd. The isothermal data fitted well to both Langmuir and Freundlich models for Cd(II) adsorption on Tectona grandis L.f. Using the Langmuir model equation, the monolayer sorption capacity of Tectona grandis L.f. was evaluated to be 29.94 mg g-1. The optimum pH value was found to be 5.5. The pseudo-first-order and pseudo-second-order kinetic models were used to describe the kinetic data. The dynamic data fitted well to the pseudo-second-order kinetic model. Cd(II) adsorption was only marginally affected in the temperature range of 30 to 50oC. An SEM of Cd(II) loaded powder showed formation of agglomerates. The FTIR of Cd(II) loaded powder showed negative shift in the wave numbers.
The pH dependent adsorption behavior of chitosan onto a cellulose model surface was studied by quartz crystal microbalance with dissipation (QCM-D). The molecular level interactions between adsorbed chitosan layers were studied by atom force microscopy (AFM) colloidal probe force measurements in the liquid phase. Adsorption of chitosan increased with pH below the solubility limit of the polymer. The adsorption behavior could not be accounted for solely on the basis of electrostatic interactions; thus a specific interaction between the polymers existed. Swelling and viscoelastic properties of the adsorbed chitosan layer were strongly influenced by pH. At high pH, the layer deswelled and became more elastic due to insolubility of the chitosan. The colloidal probe force measurements showed a rise of electrosteric repulsion after adsorption of chitosan at pH 5. Above the solubility limit of the chitosan, at pH 7, the pull-off force and its range clearly increased compared to lower pH values, indicating that the wet adhesion between chitosan-coated cellulose surfaces increased. The presented results are discussed in relation to the ability of chitosan to improve the initial wet strength of paper.
The anatomical structure and chemical composition of the stem-wall material of giant reed is considered from the viewpoint of raw material characterization for industrial fiber production. The effect of stem morphology (nodes and internodes) on pulping results and general pulp properties is discussed. The advantages of application of modern organic solvent based (organosolv) pulping technologies to giant reed are shown in comparison with the conventional (kraft) method. The conditions optimization for Ethanol-Alkali pulping (a selected organosolv pulping process) is given, and the chemical kinetics of the principal macromolecular components during ethanol-alkali pulping is described. The bleachability of organosolv pulps by short totally chlorine free (TCF) bleaching sequences using hydrogen peroxide and ozone as the active bleaching chemicals without pulp pre-delignification is examined and compared with kraft pulps. The enzymatic pre-treatment of reed organosolv pulps by commercial xylanase preparation is considered as a possibility toward the improvement of pulp bleachability.
The fungus Mucor indicus is able to produce ethanol from xylose as well as dilute-acid lignocellulosic hydrolyzates. The fungus completely assimilated 10 g/L xylose as the sole carbon and energy source within 32 to 65 h at an aeration rate of 0.1 to 1.0 vvm. The highest ethanol yield was 0.16 g/g at 0.1 vvm. Xylitol was formed intermediately with a maximum yield of 0.22 g/g at 0.5 vvm, but disappeared towards the end of experiments. During cultivation in a mixture of xylose and glucose, the fungus did not assimilate xylose as long as glucose was present in the medium. The anaerobic cultivation of the fungus in the hydrolyzate containing 20% xylose and 80% hexoses resulted in no assimilation of xylose but complete consumption of the hexoses in less than 15 h. The ethanol yield was 0.44 g/g. However, the xylose in the hydrolyzate was consumed when the media was aerated at 0.067 to 0.333 vvm. The best ethanol yield was 0.44 g/g at 0.067 vvm. The results of this study suggest that M. indicus hydrolyzate can be first fermented anaerobically for hexose assimilation and subsequently continued under oxygen-limited conditions for xylose fermentation.