Reduction In Kappa Number Research Articles

Performance of Bacillus subtilis D3d xylanase separated through optimized aqueous two-phase system in bio-bleaching of sugar beet pulp

Aqueous two-phase systems (ATPS) are potent, biocompatible, and cost-effective techniques for partitioning, concentration, or purification of biomolecules. In this work, the direct recovery of Bacillus subtilis D3d xylanase from the fermentation broth by the polymer-salt ATPS was optimized using response surface methodology (RSM). The 96% of xylanase recovery in the polyethylene glycol phase with the maximum purification factor (2.17 ± 0.02) and partition coefficient (69.87 ± 2.10) were the optimum responses that obtained at 9.5% (w/w) of polyethylene glycol, 20% (w/w) of sodium citrate, and pH 10. A good agreement between experimental and predicted results verified the adequacy of the RSM models. Furthermore, the efficiency of the crude and ATPS-recovered enzyme were evaluated in the biobleaching of sugar beet pulp. The ATPS-recovered enzymatic treatment of sugar beet pulp resulted in a higher release of reducing sugars (10.29 and 21.83 mg g−1) and caused 4.5% and 10% reduction in kappa number over crude-enzyme and control, respectively. This study indicated that ATPS-recovered xylanase compared to the crude enzyme has a promising application in the pulp and paper industry.

Xylanolytic enzyme consortia from Bacillus sp. NIORKP76 for improved biobleaching of kraft pulp.

A cellulase-free xylanolytic enzyme consortia consisting of a xylanase, arabinofuranosidase, and acetyl xylan esterase produced by Bacillus sp. NIORKP76 isolate under solid-state fermentation was assessed for its bio-bleaching ability on kraft pulp. In the biobleaching analysis, the xylanase dose of 5Ug-1 dry pulp denoted the optimum bleaching of pulp at 40°C and pH 8.0 after 2h of treatment. The reduction in kappa number of pre-treated hardwood pulp using xylanolytic enzyme consortium (XEC) was found to be ~ 55%, while solo xylanase could reduce the kappa number to 44-46%. In the case of chemical bagasse pulp, a reduction of ~ 27.5% and 19-20% was seen in kappa number using XEC and solo xylanase, respectively. Enzyme-treated pulp (HW and CB) showed a 50% reduction in hypochlorite consumption during the chlorine treatment. The current study results reveal the significant potential of xylanolytic enzyme consortium from Bacillus sp. NIORKP76 on the environmentally friendly bio-bleaching process.

Temperature and effective alkali effect on brown pulp kraft cooking

Abstract One way to obtain high quality pulp production is to improve selectivity delignification of step, maximize yield. Brown pulp yield and chemical composition were studied, with variation of temperature and effective alkali in Kraft cooking. Considering that these variables directly affect lignin removal rate and final product quality. Industrial wood chips from Eucalyptus grandis x Eucalyptus urophylla hybrids were used in this study. The cooking was performed to obtain pulps with kappa number 13, 15 and 17 for temperatures 155 °C, 160 °C and 165 °C, using the same Factor H (695). Yields were analyzed according to: total yield, rejects content and screened pulp yield. Klason lignin content, wood and pulp sugars, levels of hexenuronic acids in pulp were also determined. Results indicate that lower cooking temperatures are beneficial in relation to cooking performance, selectivity and preservation of xylans. With a screened pulp yield of 57.1 % for KN 17 at the lowest temperature 155 ºC and 55.3 % at the same KN at 165 ºC. The lowest screened pulp yield obtained, 51 %, was for KN 13 at 165 ºC, with 54.1 % with the same KN at 155 ºC. Evidencing a decreasing linear trend of screened pulp yield with temperature increase and kappa number reduction.

Prediction of Kappa number and carbohydrate degradation in oxygen delignification of Abaca fiber

Abaca banana fiber (Musa textilis) is a source of non-wood fiber that can be used as material in the manufacture of pulp. Oxygen delignification is a process to reduce lignin content in pulp with Kappa numbers as parameters. In addition, carbohydrate degradation also occurs which is indicated by the value of viscosity. The purpose of this study is to predict the decrease in Kappa number, to predict carbohydrate degradation, and to determine the best operating condition based on prediction data obtained from the kinetic reaction model. Comparison between experimental data and prediction data was also analyzed. The prediction of Kappa number was started by developing kinetic model of oxygen delignification from experimental data, in which the rate of Kappa number reduction is dependent to temperature, hydroxy ion concentration, and oxygen pressure with specific reaction order of each species. Similar steps were done for predicting carbohydrate degradation. Prediction of Kappa number and carbohydrate degradation was done at various operating conditions, which are: oxygen pressures (2–5 bar), temperatures (70–100 oC), sodium hydroxide concentrations (NaOH) (1–5%), and heating times (0–120 min). The prediction results showed that the best operating conditions were at pressure of 2 bar, temperature of 85°C, 1% of NaOH for 56.6 min with a viscosity of 878.52 ml/g. This study also performed that the experimental data were fitted well with the prediction data.

Bleach enhancement of mixed wood pulp by mixture of thermo-alkali-stable xylanase and mannanase derived through co-culturing of Alkalophilic Bacillus sp. NG-27 and Bacillus nealsonii PN-11

The Application of a combination of enzymes is the best alternative to reduce the use of chemicals in the paper industry. Bacillus sp. NG-27 and Bacillus nealsonii PN-11 are known to produce thermoalkali stable xylanse (X) and mannanase (M) respectively having potential for pulp biobleaching. The Present study, reports the production of a mixture of X + M by co-culturing of strains in SSF and standardizing its application for pulp biobleaching. Production of enzymes by co-cultivation in SSF was optimized by statistical methods. Substantial increase in the yield of enzymes; 3.61 fold of xylanase and 37.71 fold of mannanase was achieved. Application of enzyme cocktail for pulp biobleaching resulted in a 45.64% reduction of kappa number with 55 IU g−1odp of enzyme dose (xylanase:mannanase; 3:1) at pH 8.0 in 1h at 65 °C along with significant increase in brightness (11%) and whiteness (75%). The Same quality of paper as made up from chemical treated pulp can be made from enzyme-treated pulp with 30% less use of chlorine. Structural analysis of enzyme-treated pulp showed dissolution of hemicellulose as indicated by pores, cracks and increased roughness all over the surface. Cocktail of X + M produced economically in a single fermentation having all the requisite characteristics for pulp biobleaching is a highly suitable candidate for application in the pulp and paper industry.

Synergistic approach using ultrafiltered xylano-pectinolytic enzymes for reducing bleaching chemical dose in manufacturing rice straw paper.

In this study, action of ultrafiltered xylano-pectinolytic enzymes from a bacterial strain has been evaluated for bleaching of rice straw soda-anthraquinone pulp. Maximum bio-bleaching effect and release of non-cellulosic impurities were noticed with xylano:pectinolytic enzymes dose of 6.0:2.1-IU/g pulp, treatment time of 180min at 10% pulp consistency, pH8.5, and temperature 55°C. Microscopic images of bio-bleached rice straw pulp also confirmed the efficacy of ultrafiltered enzymes, as bleaching agent. This bio-bleaching treatment resulted in 15.38% and 32% reduction in kappa number and active chlorine dioxide dose, respectively, along with increase in various physical properties, burst index (12.50%), tear index (19.07%), breaking length (14.30%), double fold number (26.31%), Gurley porosity (45.32%) and viscosity (16.17%). This bio-bleaching approach not only improved the pulp quality but also reduced environmental pollution load by decreasing effluent parameters values of BOD and COD by 23.67% and 27.44%, respectively. This study indicates that use of ultrafiltered xylano-pectinolytic synergism for rice straw pulp bleaching will ultimately help in making the process eco-friendly, along with better quality pulp. This is the first report on use of ultrafiltered xylanase and pectinase, produced from a bacterial isolate, for bleaching of rice straw pulp.

Hyper Production and Eco-Friendly Bleaching of Kraft Pulp by Xylanase From Bacillus pumilus SV-205 Using Agro Waste Material

Hyper production of an extra cellular, alkali stable, cellulase free and thermostable xylanase have been produced from Bacillus pumilus SV-205 using wheat bran as a substrate under solid state fermentation. Enzyme production under optimized conditions enhanced the production level from 4510 to 65,130 ± 1000 IU/g dry substrate, which was 14.4 fold as compared to production under un-optimized conditions. The application of crude xylanase was investigated in pulp bio bleaching. The bio-bleaching of kraft pulp with xylanase was the most effective at an enzyme dose of 12.5 IU/g oven dried pulp, pH 10.0 and 120 min incubation at 60 °C. Under the optimized conditions, xylanase pre-treatment reduced Kappa number by 0.8 points and increased brightness by 1.08 points as compared with the control. The pre-treatment of pulp with xylanase resulted in 19.01% reduction in chlorine consumption by maintaining the same brightness as in control. These results clearly demonstrated that the B. pumilus SV-85S xylanase was effective as a pulp bio-bleaching agent. The decrease in chlorine consumption by pre-treatment of pulp with xylanase apparently made the bio-bleaching process not only economical but also eco-friendly. The xylanase from B. pumilus SV-205 exhibit remarkable properties which are suitable for application in paper pulp bleaching and an elevated production of xylanase by B. pumilus SV-205 under solid state fermentation over wheat bran, a cheap and easily available agro-residue would apparently reduce the enzyme cost substantially.

Lignolytic and hemicellulolytic enzyme cocktail production from Bacillus tequilensis LXM 55 and its application in pulp biobleaching

Bioprocessing of pulp requires lignolytic as well as hemicellulolytic enzymes. The present study is the first report of a cocktail of laccase (L), xylanase (X), and mannanase (M), from a single bacterium for pulp biobleaching. A novel strain Bacillus tequilensis LXM 55 produced thermo-alkali stable L + X + M. On optimization higher enzyme yield (IUml-1/fold increase) of laccase (396.35/24.16), xylanase (212.95/81.90) and mannanase (153.33/102.90) were achieved in the cocktail. Treatment of pulp with cocktail of enzymes led to 49.35% reduction in kappa number and considerable enhancement in the brightness (11.59%), whiteness (4.11%), and other pulp properties. Most importantly, no mediator system was required for the application of laccase. 40% less chlorine consumption was required to obtain the paper of the same quality as that of pulp treated without enzyme but with 100% chlorine. Therefore, this cocktail of enzymes is highly suitable for pulp biobleaching in the paper mill.

Enzyme cocktail: An opportunity for greener agro-pulp biobleaching in paper industry

An enzyme cocktail (xylanase-15U, pectinase-2U, α-amylase-2.5U, protease-2U and lipase- 1.8U) from Bacillus halodurans was applied for the biobleaching of unbleached and ODL (oxygen delignification) agro based pulp in the R&D set up of Shreyans Paper Mills Ludhiana, India, upscaling from 5 g (at lab scale) to 100 g odp (oven dried pulp). Enzyme pre-treatment was carried out at temperature and pH optima of 65 °C and 9–9.5 for 90 min followed by reduced chemical treatment. In case of unbleached agro pulp, as compared to the total chemical bleaching in mill, enzyme cocktail pre-treatment reduced the chemical usage by 50% without compromising brightness and rather with increased tensile strength (23.55%), burst factor (20.3%) and tear factor (3.17%) and reduced kappa number (19.5%). In case of ODL pulp, enzyme cocktail pre-treatment reduced the chemical usage by 40%, yet increasing brightness (2.24%), tensile strength (20.96%), burst factor (5.1%) and tear factor (8.2%) with reduction in kappa number (4.54%). The enzyme cocktail thus can make the paper manufacturing process greener, safer, economical and eco-friendly and may replace big budget ODL technologies.

Combinatorial Biobleaching of Mixedwood Pulp with Lignolytic and Hemicellulolytic Enzymes for Paper Making.

Microbial enzymes are the safe alternatives to chemical based bleaching of pulp in paper mills. For effective biobleaching, both hemicellulolytic and lignolytic enzymes are required. This study reports laccase (L) + xylanase (X) and laccase (L) + mannanase (M) enzyme concoctions for pulp biobleaching derived from Bacillus sp. LX and Bacillus sp. LM isolated from the decaying organic matter. All enzymes were thermo-alkali-stable, hence were suitable for their application in pulp biobleaching. When a mixture of L + X/L + M was used for mixedwood pulp biobleaching, 46.32/40.25% reduction in kappa number; 13.21/10.01% and 3.36/2.76% improvement in brightness and whiteness was achieved respectively. Moreover, no laccase mediator system was required in the current process. Significant changes in the structure of enzymatically treated pulp were also observed. All these properties make these concoctions of enzymes suitable for their application in pulp and paper mill.

Statistical Optimization of Biobleaching Efficacy of endo-β-1,4-xylanase from an Actinobacterium Streptomyces olivaceus (MSU3) in Comparison with Zinc Oxide Pretreated Sugarcane Bagasse Pulp Using Box–Behnken Design

ABSTRACT The bio-bleaching efficacy of endo-β-1,4-xylanase from an actinobacterium Streptomyces olivaceus (MSU3) was studied by using sugarcane bagasse pulp in comparison with chemical-mediated bleaching. Before that, the sugarcane bagasse pulp was processed with various concentrations of xylanase (20–100IU) and zinc oxide (0.2–1.0 g) individually through laboratory conditions. Simultaneously, both enzyme- and chemical-mediated bleaching process were optimized through response surface methodology by using the reaction condition containing pH 6.6, temperature 47°C with the incubation time of 3 h. The analysis of variance of the parameters expressed the maximum level of coefficient (R 2 = 0.963–0.996) with more significant (P < 0.0001). In bleaching process under-optimized conditions, the highest level of reducing sugar (110.02 mg/g), reduction of kappa number (14.69 k), degree of brightness (43.62%ISO), level of residual lignin (2.20%) with the discharge of phenolic (λ 237 = 0.119 OD), and hydrophobic (λ 465 = 0.046 OD) groups were attained in xylanase (80.0 IU) mediated bleaching than zinc oxide bleaching. Further, the effect of bleaching on processed pulp samples with loosening and changes of surface cell fiber was examined by field emission scanning electron microscopic analysis. The efficient fibrillation and porosity of pulp fiber were seen in xylanase bleached pulp than chemical-bleached pulp. These results clearly indicated that the endo-β-1,4-xylanase of the chosen actinobacterium could able to bleach the bagasse pulp effectively than the zinc oxide-mediated bleaching.

Two-step delignification of peracetic acid and alkali from sugar cane bagasse

Sugar cane bagasse was delignified in a two-step process with peracetic acid and alkali. Peracetic acid pre-treatment with concentration of 25% based on oven-dry fiber at 60 min, with a liquor to wood (L/W) ratio of 9:1 and a temperature of 50 °C improved the second stage delignification, compared with soda pulping. The second stage was carried out at three levels of temperatures, times, and 20% sodium hydroxide based on oven-dry fiber. Soda pulping at 165 °C, 120 min, 20% sodium hydroxide based on oven-dry fiber, and L/W 10:1 was selected to compare with two-step delignification. The two-step delignification reduces the severity of pulping conditions, including temperature and pressure, and subsequent imposes less risks compared with the soda pulping at 165 °C. The advantages of this method are high delignification and reduction of kappa number with respect to lower temperature and pressure compared with soda pulping. The total time in two-step was increased from soda pulping. Two optimum conditions for alkali step were obtained at 120 °C and 140 °C and 90 min for pretreated bagasse pulping, and similar properties were achieved with soda pulping at 165 °C and 120 min. The yield of fibers, Kappa number, and data analysis using Duncan method were measured and recorded.

Comparison of the Ability of Several White-rot Fungi to Biobleach Acacia Oxygen-delignified Kraft Pulp

Previous screening analyses demonstrated that the in vivo biobleaching activities of the white-rot fungi Irpex lacteus KB-1.1 and Lentinus tigrinus LP-7 are higher than those of Phanerochaete chrysosporium and Trametes versicolor. The purpose of the current study was to examine the production of extracellular enzymes of these four white-rot fungi grown on three types of low-cost media containing agricultural and forestry waste, and to evaluate the ability of the produced extracellular enzymes to biobleach Acacia oxygen-delignified kraft pulp (A-OKP). The biobleaching activity of extracellular fractions of I. lacteus, L. tigrinus, T. versicolor, and P. chrysosporium cultures was the most pronounced after 3 days of incubation with Acacia mangium wood powder supplemented with rice bran and 1% glucose (WRBG) with resultant Kappa number reduction of 4.4%, 6.7%, 3.3%, and 3.3%, respectively. Therefore, biobleaching ability of I. lacteus and L. tigrinus have been shown to be higher than of T. versicolor and P. chrysosporium, both in vivo and in vitro.

Pre-bleaching of kraft acacia pulp

AbstractKraft pulps from acacia hybrid,Acacia mangiumof 8 years old andAcacia auriculiformisof 6, 8 and 10 years old were pre-treated with oxygen, peroxyformic acid and acid treatment prior to bleaching. The kappa number reduction was 52–63 % by oxygen delignification, 31–35 % by peroxyformic acid (PFA) pre-treatment and 11–13 % by acid pre-treatment. Oxygen delignified pulp required less chlorine dioxide charge to reach target brightness. At the consumption of 30 kg ClO2/ton of pulp, the pulp brightness reached to 65–71 % for the untreated pulp, 81–85 % for the oxygen delignified pulp, 81–82 % for the PFA treatment and 79–80 % for acid pre-treated pulp. COD load in bleached effluent was much lower in oxygen delignified pulp. Cold alkali extraction of unbleached and oxygen delignified pulps was also carried out with varying alkali charge to remove hexenuronic acid (HexA) from the pulp. Xylan removal from the pulp was insignificant and resulted in no removal of HexA. Acid pretreatment removed 55.7 % to 17.8 % HexA from acacia hybrid, 57.5 % to 16.3 % fromA. auriculiformisof 10 years and 58.6 % to 20.1 % fromA. auriculiformisof 6 years old, resulting in improved final pulp brightness.

Process optimization, purification and characterization of alkaline stable white laccase from Myrothecium verrucaria ITCC-8447 and its application in delignification of agroresidues

The white laccase was produced from Myrothecium verrucaria ITCC-8447 under submerged fermentation. The media components were optimized by response surface methodology (CCD-RSM). The nutritional components (glucose and peptone) and physical parameters (pH and temperature) were optimized by response surface methodology for enhanced laccase production by Myrothecium verrucaria ITCC-8447. The enzyme activity under optimum condition exhibited 1.45 fold increases in laccase activity. The white laccase was subjected to ion exchange chromatography with 6 fold purification. The molecular weight of white laccase was ~63–75kDa as estimated by SDS-PAGE followed by the activity staining with ABTS where green bands confirmed the presence of laccase. The enzyme was stable over an alkaline pH range of 7–9 and the temperature range of 30–40°C. The characterization of white laccase was done by CD spectra, UV–visible absorption, FTIR and XRD. The Km and Vmax values of the purified laccase were 2.5mM and1818.2μmol/min/L. The delignification capability of the white laccase was determined by reduction in Kappa number (58.8%) and Klason lignin (64.7%) of wheat straw after 12h of incubation. Further the delignification was confirmed FTIR and XRD.

Dissolving pulp from jute wastes

Bangladesh Government is interested to produce rayon from jute fiber. But jute fiber is an expensive raw material. Jute cuttings (JC) and jute caddis (CD) are generated as wastes in the jute mill. In this investigation dissolving pulp was produced from low grade jute (LGJ), JC and CD with 90% formic acid (FA) treatment at the boiling temperature for 4 h. JC showed the highest pulp yield (62.3%) and CD showed the lowest pulp yield (58.0%). In this process 12–13% lignin and 25–27% hemicelluloses were also separated from the spent liquor, which can integrate biorefinery. FA pulps were further alkali extracted by varying amount of alkali charge at 25 and 90 °C for 120 min. Alkali extraction reduced kappa number and residual pentosan content in pulp. In the D0EpD1 bleaching sequence, brightness of LGJ and JC pulps reached to 83–86% and pulp purity to 96% with fock reactivity of 61–67%.

Spectral characterization and surface morphology of delignification of Kraft pulp with carbamide peroxide

The study focuses on delignification of Kraft pulp using carbamide peroxide as bleaching agent. The Kappa number reduction of bleached pulp is favored at low consistency of pulp and higher reaction temperature. The optimal Kappa reduction was achieved at temperature of 68 °C, 0.8 g of carbamide peroxide per 100 ml of solution and 2% consistency in the range of variables studied. Fourier transform infrared spectral analysis done on bleached pulp to determine bond stretches and bending vibrations. X ray diffraction spectral data observation provided that the crystallinity index increased from 81.7% before bleaching to 85% after bleaching which indicates the removal of amorphous species in sample. FT-RAMAN spectral analysis concludes the possible conformational changes pre and post bleaching. The absence of some native lignin bands post bleaching indicates lignin removal. Scanning electron microscope images of bleached pulp samples were observed with less amounts of fibrillar type lignin network on surface of pulp fibers when compared to unbleached samples. The activation energy and rate constants were determined for delignification of pulp using carbamide peroxide process. Sequential treatment of Kraft pulp with carbamide peroxide and sodium percarbonate were also evaluated.

Using online bubble size and total dissolved solids measurements to investigate the performance of oxygen delignification

The main target of oxygen delignification is to continue delignification that started in cooking in a more selective manner than occurs in the digester (i.e., remove a substantial fraction of the residual lignin using oxygen and alkali at a moderate temperature). Delignification with oxygen is a gentler way of reducing the kappa number than extended cooking. Lowering inlet kappa to bleaching also decreases bleaching chemicals consumption and, because of this, reduces organic wastewater load from bleaching. We studied the performance of oxygen delignification by installing bubble size imaging systems and refractometers, which measure dissolved dry solids in the oxygen stage feed. Based on these measurements, we gathered information about gas dispersion (bubble size distribution) and the behavior of dissolved matter in the hardwood mill’s oxygen delignification stage. Our goal was to investigate the effects of different variables on the oxygen stage’s gas dispersion, kappa reduction, yield, and pulp quality. Gas dispersion improved (i.e., average bubble size decreased) when the chemical mixer speed increased. Increasing the mixer speed and the amount of oxygen yielded higher kappa number reductions and increased the amount of dissolved organic matter.

Production and purification of xylanase from alkaliphilic Bacillus licheniformis and its pretreatment of eucalyptus kraft pulp

Abstract Xylanases from bacterial sources have potential applications in various industrial processes. In the present study, the effect of enzymatic pre-treatment on pulp bleaching has been investigated using purified xylanase from alkaliphilic Bacillus licheniformis strain Alk-1. The xylanase produced by present isolate while growing on wheat bran was purified to homogeneity by 5.84-fold purification with ~15.97% recovery by anion exchange chromatography using DEAE-cellulose. The estimated molecular weight of the xylanase was ~46 kDa. The optimal pH and temperature for xylanase activity were pH 9.0 and 60 °C, respectively. The enzyme showed good activity retention (80%) after 1 h incubation at 60 °C and pH 9.0. Enzyme activity was stimulated by Ca2+, Fe2+ and Mg2+ and inhibited by Cd2+, Hg2+ and Cu2+ at 2 mM and 10 mM conc. For xylan, the enzyme gave a Km value of 5.26 mg/mL and Vmax value of 433 μM/min/mg proteins when the reaction was carried out at 60 °Cand pH 9.0. Pre-treatment of kraft pulp with xylanase showed 19% reduction in kappa number, compared to control pulp, after 2 h treatment. The SEM and FTIR analysis of xylanase-treated pulp revealed significant morphological and structural changes on pulp fibres. GC-MS analysis of filtrates from control and xylanase-treated pulps showed variation in the presence of different plant-derived organic compounds. The present work finds potential application in paper production by making it cleaner and ecofriendly process.

A logical and sustainable approach towards bamboo pulp bleaching using xylanase from Aspergillus nidulans

Driven by the environmental benefits that bio-bleaching could bring, the interest in xylanase has received enormous attention and hence, the search of xylanase with properties like no cellulase activity, function at elevated temperatures and pH continues. The present study reports the production of extracellular xylanase from Aspergillus nidulans using waste agro-residues as substrate. The optimum temperature (60 °C) and pH (9.0), classified the xylanase as thermo and alkali tolerant. The addition of salt of Mn2+ increased the xylanase activity to almost double; however, these ions were unable to protect the enzyme from thermal inactivation. The FTIR spectra of bamboo pulp treated with this xylanase, revealed reduction in lignin as evident from reduced peak intensity coupled with the reduction in kappa number. The SEM image of enzyme treated pulp, exhibited dissociation in fibers exposing the internal structure with slight roughness. Swelling was also observed there by increasing its thickness which eventually helped in improving its physical properties. The bleaching efficacy of indigenous xylanase as indicated in this study, has established its competence as a promising candidate for pre-treating the bamboo pulp.