Pretreatment Of Pulp Research Articles

Cellulose Nanofibers Prepared via Pretreatment Based on Oxone® Oxidation.

Softwood sulfite bleached cellulose pulp was oxidized with Oxone® and cellulose nanofibers (CNF) were produced after mechanical treatment with a high-shear homogenizer. UV-vis transmittance of dispersions of oxidized cellulose with different degrees of mechanical treatment was recorded. Scanning electron microscopy (SEM) micrographs and atomic force microscopy (AFM) images of samples prepared from the translucent dispersions showed individualized cellulose nanofibers with a width of about 10 nm and lengths of a few hundred nm. All results demonstrated that more translucent CNF dispersions could be obtained after the pretreatment of cellulose pulp by Oxone® oxidation compared with the samples produced without pretreatment. The intrinsic viscosity of the cellulose decreased after oxidation and was further reduced after mechanical treatment. Almost translucent cellulose films were prepared from the dispersions of individualized cellulose nanofibers. The procedure described herein constitutes a green, novel, and efficient route to access CNF.

Enzymatic pretreatment for the improvement of dispersion and film properties of cellulose nanofibrils

In the present study, cellulose nanofibrils (CNF) were produced from unbleached eucalyptus pulp, and the effect of enzymatic treatment on the properties of CNF was studied. Moreover, the mechanism of enzymatic treatment on the dispersion and film properties of CNF was speculated. The xylanase pretreatment facilitated the deconstruction of pulp into CNF via mechanical shearing and high-pressure homogenization, while the hemicellulose composition was preserved.Compared to the control, the CNF suspensions made from the xylanase pretreated pulp were more crystalline with higher dispersion, optical and rheological properties. CNF films were produced with a vacuum filtration process. The optical and mechanical strength properties of the CNF films were improved by the removal of hemicellulose. It was found that the carboxyl and hydroxyl groups played key roles in affecting the dispersion and film properties of the CNF. The carboxyl group content increased after the enzymatic pretreatment, which benefits the even distribution of CNF in water. The mechanical strength of the CNF films was further improved by exposing the hydroxyl group when lignin-carbohydrate complexes were de-structured by the enzymes. This study expanded the application of CNF produced from unbleached pulp. The theoretical foundation for stabilizing the CNF suspension and the high-speed dehydration of CNF films were explored for the continuous roll to roll production of CNF film.

Physicochemical treatment for improving bioconversion of cassava industrial residues

In the present study, a comparison of two types of microwave pretreatment such as microwave assisted alkali and microwave assisted acid were studied using cassava pulp as the substrate. The effect of pretreatment agent concentration, microwave power and pretreatment time on enzymatic saccharification was studied using a response surface method according to Central Composite design. Under optimized conditions, microwave assisted alkali pretreatment of cassava pulp with 2.27% NaOH at 125 W for 18 min followed by enzymatic hydrolysis gave reducing sugar yield of 0.472 g g−1 dry biomass, while microwave assisted acid treatment with 1.95% H2SO4 at 135 W for 25 min showed reducing sugar yield of 0.306 g g−1 dry biomass. The yield from microwave assisted alkali was higher and was 2.7 times higher than that obtained with raw cassava pulp. Microwave assisted liquefaction of pretreated cassava pulp at 100 W for 30 min using amylase lowered the process time. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 577–583, 2018

Thermally Stable Cellulose Nanocrystals toward High-Performance 2D and 3D Nanostructures.

Cellulose nanomaterials have attracted much attention in a broad range of fields such as flexible electronics, tissue engineering, and 3D printing for their excellent mechanical strength and intriguing optical properties. Economic, sustainable, and eco-friendly production of cellulose nanomaterials with high thermal stability, however, remains a tremendous challenge. Here versatile cellulose nanocrystals (DM-OA-CNCs) are prepared through fully recyclable oxalic acid (OA) hydrolysis along with disk-milling (DM) pretreatment of bleached kraft eucalyptus pulp. Compared with the commonly used cellulose nanocrystals from sulfuric acid hydrolysis, DM-OA-CNCs show several advantages including large aspect ratio, carboxylated surface, and excellent thermal stability along with high yield. We also successfully demonstrate the fabrication of high-performance films and 3D-printed patterns using DM-OA-CNCs. The high-performance films with high transparency, ultralow haze, and excellent thermal stability have the great potential for applications in flexible electronic devices. The 3D-printed patterns with porous structures can be potentially applied in the field of tissue engineering as scaffolds.

Biobleaching of paper pulp with xylanase produced by Trichoderma asperellum.

This study is aimed at assessing the biobleaching activity of fungal xylanase on paper pulp isolated from Tirumala forest, Eastern Ghats of India. Of the 98 fungal isolates obtained after initial screening, eight isolates were selected and one potential strain was further cultivated under submerged fermentation for production of xylanase. The biobleaching efficiency on waste paper pulp and paper industry effluent was tested with crude enzyme. Xylanolytic activity by the chosen organism in submerged fermentation reached the maximum (981.1U ml-1) on the 5th day of incubation. Molecular characterisation of the isolate led to its identification as Trichoderma asperellum which exhibited the production of enzyme even at alkaline pH of the culture medium. Xylanase pretreatment of paper pulp had shown reduction in the Kappa number by 4.2 points and increased brightness by 4.0 points. FTIR and SEM studies revealed loosening of pulp fibres after enzyme treatment. In conclusion, xylanase of Trichoderma asperellum was effective as a pulp biobleaching agent and the process is economical as well as eco-friendly.

Effects of the Surface Morphology and Conformations of Lignocellulosic Biomass Biopolymers on Their Nanoscale Interactions with Hydrophobic Self-Assembled Monolayers.

The effects of the morphology and conformations of the surface biopolymers present on lignocellulosic biomass as well as their steric hindrance on enzymatic adsorption to biomass surfaces remain elusive. In a step to better understand these effects, nanoscale steric forces between a model surface that represents the hydrophobic residues of a cellulase enzyme and a set of reference lignocellulosic substrates were measured using atomic force microscopy (AFM) in liquid media. The reference substrates investigated were prepared by kraft, sulfite, and organosolv pulping pretreatment methods and varied in their surface lignin, xylan, and acetone extractives' contents. Measured steric forces were quantified through fitting to a model developed to describe polyelectrolytes brushes in terms of a brush thickness and a brush grafting density. Our data indicated that cellulose microfibrils extend from the microfibril matrix leading to a long-range steric repulsion and low attractive forces to the hydrophobic model of the enzyme, suggesting that steric hindering can be a possible mechanism for nonproductive binding of enzymes to cellulose. When the amount of xylan increased in the absence of lignin, steric repulsions between the hydrophobic model of the enzyme, and biomass biopolymers decreased as a result of collapsed cellulose microfibrils and adhesion forces increased. This suggests that leaving a small amount of xylan after biomass pretreatment can help improve enzymatic binding to cellulose. Irrespective of the type of lignin present on biomass, grafting densities increased and brush thicknesses decreased compared to those of lignin-free substrates. When compared to lignin-free substrates, lignin-containing substrates had higher attractive forces and lower steric repulsive forces. In addition, AFM images of the reference substrates in the wet and dry states showed that lignin precipitates on the biomass surface where kraft lignin had the highest particle size leading to a limited accessibility of the enzyme to the cellulose in biomass. When the effects of lignin precipitate size, the adhesion force, and steric forces on nonproductive enzymatic binding were all considered, our results indicate that organosolv pretreatment should be the treatment of choice to minimize enzymatic nonproductive binding to lignin.

Effect of Alkali Pectinase Pretreatment on Bagasse Soda-Anthraquinone Pulp

Pectinase pretreatment prior to bagasse soda-anthraquinone (AQ) pulping was conducted, and the effects of pectinase pretreatment on the pulp strength properties, energy consumption, and pulpability were evaluated in this study. Considering the pulp properties, the optimal conditions for the pectinase pretreatment were a pectinase dosage of 60 U/g (with respect to oven-dry bagasse) and 60-min treatment time. Compared with the control pulps obtained under the same treatment conditions with enzyme pretreatment (just without enzyme addition), the pretreated pulps attained a reduction in kappa number of 17.8% and an increase in total pulp yield of 15.8%. Moreover, higher breaking length, burst factor, and tear factor after soda-AQ pulping were found in the pectinase-pretreated samples, which suggests some improvements in pulp strength properties. With pectinase treatment, a 1% reduction in alkali charge and 20% decrease in pulping time were observed in subsequent pulping stages without affecting the pulp properties. Pectinase treatment prior to pulping seems to be a promising, economically feasible, and eco-friendly concept.

Enhanced methane production and its kinetics model of thermally pretreated lignocellulose waste material

The objective of the study was to assess the effect of substrate concentration by specific methanogenic activity (SMA) of thermally pretreated pulp and paper mill sludge. Different substrate concentration through food to microorganism ratio varied from 1.0 to 3.0 was carried out in a mesophilic condition as biochemical methane potential assay. Experimental results offered that cellulose removal rate spikes up to 60.2%. The specific methane gas production and biodegradability were increased up to 303mL of CH4/g VS and 73% respectively. By increasing the substrate concentration, SMA was significantly improved in a linear manner. The net energy of 8735kJ was gained after thermal pretreatment. In addition to that three kinetics model were used, among that the modified Gompertz and logistic function models represent and reproduce the experimental data, while the earlier has the better fit.

3-12-4 メカノケミカルパルピング前処理によるバイオエタノール製造の経済性環境性評価(3-12 システム・評価,Session3 バイオマス等,研究発表)

3-12-4 メカノケミカルパルピング前処理によるバイオエタノール製造の経済性環境性評価(3-12 システム・評価,Session3 バイオマス等,研究発表)

English

In this study, pretreatment of banana pulp using eggshells in both calcined and un-calcined forms to examine the extent of hydrolysis was conducted. Reactor CO containing banana pulp and inoculum but with no eggshells added was used as the control, while reactors C1, C2, C3, C4, and C5 containing banana pulp and inoculum were spiked with 1, 3, 5, 7, and 9 g of un-calcined eggshells and calcined eggshells, for experiment 1 and 2, respectively. Anaerobic digestion was carried out at mesophilic temperature (35°C) for a period of 20 days. Digester C3 with 5 g of calcined eggshells gave the largest cumulative biogas yield of 2343 mL with 62% CH4, followed by digester C5 with 9 g of un-calcined eggshells which gave 2032 mL with 51.9% CH4. The least biogas yield of 10 mL was obtained in digester C5 with 9 g of calcined eggshells additive. Key words: Anaerobic digestion, banana pulp hydrolysis biogas, eggshells.

Unleashing the potential of ligninolytic bacterial contributions towards pulp and paper industry: key challenges and new insights.

Lignocellulose biomass predominantly constitutes the main feedstock for pulp and paper industry. Though some products of pulp and paper industry require the presence of lignin content, for most of the useful products formation lies in the efficient and selective removal of lignin component to make use of the intact cellulose fraction during the pretreatment of pulp. Lignin is a recalcitrant heteropolymer comprised of several complex stable bonds and linkages. The chemicals or intense energy processes used for delignification process release the hazardous chemicals compounds in the wastewater which cause toxicity and environmental pollution. The implementation of bacterial species has elucidated an effective approach in the generation of value-added products while degrading lignin from pulp biomass as well as detoxification of effluent. The direct use of bacterial cells in lignocellulose biomass and wastewater streams is promising as it outperforms the practical and technical constraints largely confronted by fungal and enzymatic means. The present review paper thus unleashed the potential of ligninolytic bacteria towards delignification of pulp biomass and treatment of effluent together with bioconversion of biomass and lignin into value-added products. Graphical abstract Schematic illustration of potential possible contribution of ligninolytic bacteria towards pulp and paper industry.

Catalytic and non-catalytic pyrolysis of Kraft pulp waste into anhydrosugars containing bio-oils and non-phytotoxic biochars

The catalytic and non-catalytic fast pyrolysis process for converting Kraft pulp paper waste into bio-oil and biochar was studied. Catalysis free pyrolysis of untreated Kraft pulp resulted on good yields of bio-oil (39% at 400°C), showing a relative high concentration of levoglucosan, while phosphoric acid-pretreated pulp produced lower yields of bio-oil (max. value 14% at 350°C) being levoglucosenone the main component. The catalytic pyrolysis of pretreated pulp employing silica led to a high yield of the liquid fraction (57% at 400°C) with a high selectivity to levoglucosan. The biochar produced from as received pulp could be envisaged for soil amendment. It displayed a relatively high specific surface area, showing micro and mesoporosity. Besides, no phytotoxic effect of the biochar obtained at 350°C was recorded.

Structural Changes of Lignin from Wheat Straw by Steam Explosion and Ethanol Pretreatments

Effects of the pretreatment of wheat straw by steam explosion and ethanol were evaluated relative to the structural changes of lignin from the pretreated pulp. The lignin from steam explosion pulp (LS), lignin from steam blasting residual liquid (LL), lignin from ethanol pretreatment pulp (LE), lignin from black liquor (LB), and lignin from wheat straw (LW) were separated, and the structural characteristics of the lignin fractions were compared based on analyses of Fourier transform-infrared, ultraviolet, thermogravimetric, and 1H and 13C nuclear magnetic resonance spectra. The proportions of the three structural units in all lignin fractions clearly changed during the pretreatment process because of inter-conversion reactions. The conjugated structure of lignin was destroyed in the pretreatment process and was also affected by the alkali extraction process. The alcoholic hydroxyl links on the aliphatic side chain were partly transformed into carbonyl groups during ethanol pretreatment. Demethoxylation occurred in all lignin fractions during the ethanol pretreatment and steam explosion process. The thermal stability of the LB fraction was relatively high because of the condensation reaction.

Study of inhibition of browning of clarified banana juice

Browning is the second largest cause of quality loss in fruits and vegetables. It seems to be the most severe problem during banana pulp processing. Effect of two anti-browning pretreatments <italic>viz</italic>. addition of ascorbic acid (200-1200 ppm) and blanching the peeled fruits (90°C for different periods) prior to enzymatic clarification banana juice were studied. Effectiveness of anti-browning pretreatments to the pulp was evaluated by measuring the browning in terms of Browning Index in prepared clarified juices. Clarified banana juice obtained from untreated pulp had dark brown colour with initial browning index value of 0.411 which continuously increased and reached to 0.586 at 24 h of storage. Pretreatment of pulp with 1000 ppm of ascorbic acid or heating at 90°C for 6 minute was observed to retain the natural colour of prepared clarified juice without marked changes up to 4 h of storage at room temperature. However preheating of banana pulp observed to be caused cooked flavour and altered the original taste of the clarified juices.

Enhanced Separation of the Organic Fraction from Paper Mill Effluent for Energy Recovery

In this study pre-treatment of pulp and paper mill sludge was investigated to enhance the energy recovery by anaerobic digestion. Two approaches were followed using hydrolytic enzymes or microbiological treatment at 30 °C. In the first attempt, anaerobic digestion of the whole sludge, no significant improvement of the methane production potential was found. In the second test series only the liquid phase after pre-treatment and solids separation was anaerobically degraded. This option provided up to ten times increased methane production compared to the untreated sample. Sludge mass reduction between 6 and 13 % was achieved after pre-treatment. Moreover this concept can be easily integrated in the established wastewater treatment scheme utilizing an existing upflow anaerobic sludge blanket reactor.

Application of pure, thermostable, alkali-tolerant xylanase in bleaching of oxygen-delignified pine kraft pulp

The effect of oxygen (O2)-delignified pine kraft pulp pretreatment by high-purity, thermostable, and alkaline-tolerant xylanases on elemental chlorine free (ECF) bleaching of O2-delignification kraft pulp was studied. The study found that xylanase pretreatment preserved the intrinsic viscosity and yield of O2-delignified pulp while causing about 7% of delignification with high delignification selectivity. The xylanases with high purity, higher thermostability (75°C~80°C) in highly alkaline media (pH 8.0~9.5) could be applied on an industrial scale. Pulp pretreatment by the high-purity, thermostable, and alkaline tolerant xylanases could improve pulp brightness or reduce the chlorine dioxide (ClO2) consumption. In a D0ED1D2 bleaching sequence using the same amount of ClO2, the xylanase-pretreated pulp obtained a higher brightness (88.2% vs. 89.7% ISO) at the enzyme dose of 2 U/g pulp; or for the same brightness as control (88.2% ISO), the ClO2 dosage in the D0 stage was reduced by 27%, which represents a 16% savings in total ClO2 used for bleaching.

Improved Strength of Peroxide-Bleached Deinked Pulp after TEMPO-Mediated Oxidation at Medium Consistency

Deinked pulp was pretreated using the 4-acetamido-2,2,6,6,- tetramethyl-pipelidine-1-oxyl radical (TEMPO)/NaBr/NaClO system and then bleached using hydrogen peroxide to achieve a medium pulp consistency. The effect of the amount of oxidant NaClO addition on the peroxide bleaching of deinked pulp was studied. The treated pulp was characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The characterization of XRD and SEM showed that the treated pulp had a higher degree of crystallinity and more fibrillation than untreated pulp. Fiber quality analysis also revealed that the treated pulps had more fines and shorter fiber length than the untreated pulp. A handsheet test showed that the deinked pulps pretreated with the TEMPO system exhibited high tensile index values. The tensile index of the TEMPO pretreated pulp was 17% higher than that of the pulp bleached by hydrogen peroxide alone.

Effect of Eucalypt Pulp Pretreatment with Hot Acid Hydrolysis on (aZe)DP and (aZe)(EP)P Bleaching Performance

The effect of pulp pretreatment with hot acid hydrolysis on high consistency ozone bleaching was evaluated. An experimental plan was set up involving the full optimization of the A-stage and its application in Elemental Chlorine Free–ECF–[A/(aZe)DP and A(aZe)DP] and Total Chlorine Free–TCF–[A/(aZe)(EP)P and A(aZe)(EP)P] sequences for eucalypt kraft pulp bleaching. The A-stage removed a significant amount of lignin and HexA from the pulp, and the subsequent Z-stage remained efficient after completion of the A-stage. The chemical savings caused by the A-stage were significant (∼7 kg ClO2/adt). The optimum conditions for the A-stage were pH 3.0, 90°C for 120 min, and 10% consistency. The strength properties of pulps bleached with the (aZe)DP (reference) and A/(aZe)DP ECF sequences were similar, but the TCF sequence A/(aZe)(EP)P delivered slightly lower strength properties than the ECF sequences. Fiber peeling studies indicated that the HexA present in the kraft pulp is not concentrated on the fiber surface, as previously thought.

Enhancing fermentable sugar yield from cassava pulp for bioethanol production: microwave-coupled enzymatic hydrolysis approach.

Cassava pulp, a potential biological feedstock for ethanol production has been subjected to microwave-assisted alkali pretreatment and microwave-coupled enzymatic hydrolysis. Microwave pretreatment may be a good alternative as it can reduce the pretreatment time and improve the enzymatic activity during hydrolysis. Liquid to solid ratio for the pretreatment of cassava pulp was found to be 20:1. Cassava pulp was pretreated at various NaOH concentration, microwave temperature and gave maximum yield of reducing sugar with 1.5% NaOH at 90 °C in 30 min than conventional alkali pretreatment after enzymatic hydrolysis. The subsequent enzymatic saccharification of pretreated cassava pulp using α amylase dosage of 400 IU at microwave temperature of 90 °C resulted in highest reducing sugar yield of 723 mg/g pulp. Microwave-assisted alkali pretreatment improved the enzymatic saccharification of cassava pulp by increasing its accessibility to hydrolytic enzymes. Microwave-assisted alkali pretreatment and microwave-coupled enzymatic hydrolysis are found to be efficient for improving the yield of reducing sugar.

Effects of Pulp Pre-treatment and Grinder Clearance on the Manufacturing Characteristics of Microfibrillated Cellulose

Effects of Pulp Pre-treatment and Grinder Clearance on the Manufacturing Characteristics of Microfibrillated Cellulose