Bleached Sulfite Pulp Research Articles

Sustainable Surface Engineering of Lignocellulose and Cellulose by Synergistic Combination of Metal-Free Catalysis and Polyelectrolyte Complexes.

A sustainable strategy for synergistic surface engineering of lignocellulose and cellulose fibers derived from wood by synergistic combination of metal‐free catalysis and renewable polyelectrolyte (PE) complexes is disclosed. The strategy allows for improvement and introduction of important properties such as strength, water resistance, and fluorescence to the renewable fibers and cellulosic materials. For example, the “green” surface engineering significantly increases the strength properties (up to 100% in Z‐strength) of chemi‐thermomechanical pulp (CTMP) and bleached sulphite pulp (BSP)‐derived sheets. Next, performing an organocatalytic silylation with a nontoxic organic acid makes the corresponding lignocellulose and cellulose sheets hydrophobic. A selective color modification of polysaccharides is developed by combining metal‐free catalysis and thiol‐ene click chemistry. Next, fluorescent PE complexes based on cationic starch (CS) and carboxymethylcellulose (CMC) are prepared and used for modification of CTMP or BSP in the presence of a metal‐free catalyst. Laser‐scanning confocal microscopy reveals that the PE‐strength additive is evenly distributed on the CTMP and heterogeneously on the BSP. The fluorescent CS distribution on the CTMP follows the lignin distribution of the lignocellulosic fibers.

Studies on the adverse effects of bleached sulphite pulp mill effluents on physiology of liver function in Heteropneustes fossilis

Studies on the adverse effects of bleached sulphite pulp mill effluents on physiology of liver function in Heteropneustes fossilis

Analysis of Gill Structure from a Fresh Water Fish (Heteropneustes fossilis) Exposed to Bleached Sulfite Pulp Mill Effluents.

The present communication reports toxic effects of bleached sulfite pulp mill effluents in fish (Heteropneustes fossilis) gills, with optical, scanning electron, and transmission electron microscopy. The general adverse effects include dilation of the primary lamellar wall, curling of secondary lamellar terminals, displacement of epithelial cell layers, degeneration of secondary lamella, deposition of mucous, and severe congestion in the gill arch. The significant shortening of secondary lamellae, widening of lamellar tips, and significant decrease in the number of mitochondria in chloride cells as compared to controls are some specific effects of bleached sulfite pulp mill effluents. Scanning electron microscopy demonstrated tearing of tissues in gill lamellae and arches. Transmission electron microscopy revealed membrane distortion of mitochondria in chloride cells, loss of uniformity of microvilli in pavement cells, and abnormalities in nuclear shape in different cells of effluent-exposed fish gills. Toxicity of the bleached sulfite pulp mill effluents and its impact on fish are discussed in the light of existing literature. Further, the importance of microscopy in toxicological evaluation of environmental pollutants is emphasized in view of its specific application potential.

Modifying cellulose fibers by adsorption/precipitation of xylan

Xylan was precipitated on bleached and unbleached softwood kraft pulps (SKPB and SKPUB), a bleached sulfite pulp, and viscose fibers to investigate the influence on physical properties of handsheets as well as to gain more detailed information of the distribution of adsorbed xylan on cellulosic surfaces. The adsorption step was carried out at constant conditions. The values of the parameters were chosen after a series of different adsorption steps (as presented elsewhere) also in regard as a possible industrial application. Afterwards, suspension and physical strength properties of unrefined and refined samples were determined. Refining resulted in a stronger increase in the beating degree of the pulps with additional xylan than the reference samples. The water retention value was not significantly changed. Comparing the tensile index of the handsheets versus the beating degree a remarkable increase in the strength properties was not observed. The investigation of the surface of the SKPB fibers via ATR suggests that precipitated xylan is heterogeneously and nonuniformly distributed. On cellulose model films, particles could be detected via atomic force microscopy. Phase images recorded with OH-functionalized tips suggested that these particles consist of xylan. An inhomogeneous distribution of xylan could be a reason that there is no measurable influence on the strength properties of the handsheets.

Evolution and impact of cellulose architecture during enzymatic hydrolysis by fungal cellulases

The enzymatic hydrolysis of cellulose is still considered as a main limiting step of the biological production of biofuels from ligno-cellulosic biomass. Glycoside hydrolases from Trichoderma reesei are currently used to produce fermentable glucose units from degradation of cellulose packed in a complex assembly of cellulose microfibrils. The present work describes the structural evolution of two prototypical samples of cellulose (a micro-crystalline cellulose and a bleached sulfite pulp) over 5 length scale orders of magnitude. The results were obtained through wide angle, small angle and ultra-small angles synchrotron X-ray scattering, completed by Small Angle Neutron Scattering and particle size analyzers. These structural evolutions were followed as a function of enzymatic conversion. The results show that whereas there is no change at the nanometer scale, drastic changes occur at micron. The observed decrease of the size of the cellulose particles is accompanied by a smoothing of the crystalline surfaces that can be explained by a two-step mechanism of the enzymatic hydrolysis.

Characterization of direct cellulase immobilization with superparamagnetic nanoparticles

Methods of cellulase immobilization on magnetic particles via glutaraldehyde binding were studied. The binding was confirmed by transmission electronic microscopy (TEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and vibrating sample magnetometry (VSM). Samples analyzed by TEM and XRD showed that the magnetic particles with or without bound cellulase were all nanosized particles with a mean diameter of 11.5 nm, and the binding process did not cause significant changes in particle size and structure. Analysis by FTIR showed that the binding of cellulase to the magnetic nanoparticles might be via covalent bonding between residual amine groups on Fe3O4 nanoparticles and amine groups of the cellulase. The VSM analysis showed that magnetic nanoparticles with or without bound cellulase were all superparamagnetic. The immobilized cellulase had a wider pH and temperature range and improved storage stability compared with the free enzyme. Determination of the Michaelis constants revealed that the immobilized cellulase had a greater affinity for the cellulosic substrate than the free enzyme. The immobilized cellulase showed better performance on hydrolysis of steam-exploded corn stalks than of bleached sulfite bagasse pulp.

Characterization of Poly (Methyl Acrylate) Grafted Bleached Sulfite Pulp Fibers using AFM, AEM, EDS and STEM

Sulfite pulp fibers were grafted by poly (methyl acrylate) at a low‐consistency (1% pulp consistency) and medium‐consistency (10% pulp consistency). It is of fundamental interest to determine the distribution of the polymer chains obtained at different fiber concentrations during grafting. In this study, modern analytical tools such as atomic force microscope (AFM), energy dispersive spectrometer (EDS), and scanning transmission electron microscope (STEM) were used for investigating the distribution of the polymer chains in the fiber matrix. AFM images in tapping mode showed that the fiber surface was covered with in‐situ generated polymers. The X‐ray mapping of Na in the cross‐section of the hydrolyzed grafted fibers by using EDS in combination with Na line scans by STEM showed that the distribution of poly (methyl acrylate) was affected by the pulp consistency during grafting; at a medium‐consistency condition the outer region of the fiber structure had a higher polymer concentration than the inner region. On the other hand, at a low‐consistency condition, grafting occurred uniformly across the fiber wall structure.

Homogeneous Suspensions of Individualized Microfibrils from TEMPO-Catalyzed Oxidation of Native Cellulose

Never-dried native celluloses (bleached sulfite wood pulp, cotton, tunicin, and bacterial cellulose) were disintegrated into individual microfibrils after oxidation mediated by the 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical followed by a homogenizing mechanical treatment. When oxidized with 3.6 mmol of NaClO per gram of cellulose, almost the totality of sulfite wood pulp and cotton were readily disintegrated into long individual microfibrils by a treatment with a Waring Blendor, yielding transparent and highly viscous suspensions. When observed by transmission electron microscopy, the wood pulp and cotton microfibrils exhibited a regular width of 3-5 nm. Tunicin and bacterial cellulose could be disintegrated by sonication. A bulk degree of oxidation of about 0.2 per one anhydroglucose unit of cellulose was necessary for a smooth disintegration of sulfite wood pulp, whereas only small amounts of independent microfibrils were obtained at lower oxidation levels. This limiting degree of oxidation decreased in the following order: sulfite wood pulp > cotton > bacterial cellulose, tunicin.

Lignin reactions in oxygen delignification catalysed by Mn(II)-substituted molybdovanadophosphate polyanion

Abstract The lignin oxidation in the oxygen delignification/bleaching process catalysed by Mn(II) substituted heptamolybdopentavanadophosphate polyanion (HPA-5-MnII) was studied using monomeric lignin model compounds and Eucalyptus globulus dioxane lignin adsorbed on the bleached sulphite pulp. The analysis of reaction products after lignin models oxidation in the presence HPA-5-MnII and the parent heptamolybdopentavanadophosphate polyanion (HPA-5) showed similar qualitative and quantitative patterns, indicating the identical lignin oxidative delignification mechanisms with both catalysts. The higher delignification selectivity of the pulp in the reaction system HPA-5-MnII/O2 than with HPA-5/O2 was explained by the protective effect of MnII in the heteropolyanion towards oxidative degradation of polysaccharides. The study of lignin adsorbed on bleached sulphite pulp, in the HPA-5-MnII/O2 delignification system, showed the cleavage of β-O-4 linkages as the major contribution to the lignin depolymerisation. The formation of Cα-O-polysaccharide linkages in β-O-4 structures of lignin during the delignification was observed.

Chemiluminescence from the thermal and photo-oxidation of several wood pulps

Thermo- and photo-oxidative degradation of several wood pulps; thermo-mechanical pulp (TMP), bleached sulfite pulp (NBSP), bleached kraft pulp (NBKP), unbleached kraft pulp (NUKP) and filter paper, were examined mainly by chemiluminescence (CL). The CL behavior of the pulps was extremely different from each other and the decreasing order of its intensity was: TMP>NBKP>NBSP>NUKP>Filter paper. In the case of the bleached pulps; NBKP, NBSP and filter paper, the CL intensity increased with photo-irradiation time, but only a small change in its intensity was observed in the unbleached pulps; TMP and NUKP. From the measurement of ultraviolet-visible (UV-V) spectra of the degraded samples, a small change in the CL intensity observed in the unbleached pulps was ascribed to the shielding and/or absorption of the emitted light by the colored materials in the pulps.

漂白排水のＡＯＸ除去へのＵＡＳＢ法適用実験

Removal of COD and AOX (Adsorbable Organic Halide) from bleached sulfite pulp mill effluent was studied with the objective of applying a UASB process for AOX control at bleached pulp mills. A mixture of chlorination stage filtrates and evaporator condensate (2: 1) was supplied to a 30liter UASB reactor. It was treated successfully, achieving about 85% removal of COD and 40% to 50% removal of AOX under a COD space load of 17kg/m3/d at 35°C. When the reactor was fed with a mixture of alkaline extraction stage filtrates and evaporator condensate (2: 1), COD and AOX removal ratios were about 80% and about 30% respectively, under a COD space load of 12kg/m3/d at 35°C. The AOX removal was found to be inversely proportional to COD space load.

Accessibility of sulfite pulp to lignin peroxidase and marker proteins with respect to enzymatic bleaching

The diffusion of proteins into unbleached and bleached sulfite pulp fibers was investigated. Pulp specimens were infiltrated with crude lignin peroxidase of Phanerochaete chrysosporium (40,000–46,000 Da), ovalbumin (43,000 Da) and myoglobin (16,500 Da), cross-linked by glutaraldehyde and processed for immunoelectron microscopy. Ultra-thin sections of the specimens were labeled for the proteins with antibodies conjugated to colloidal gold. The penetrability of the fibers was determined qualitatively by comparison of the gold-labeling density inside and outside the fibers. The results showed great differences with respect to the penetrability of individual fibers in one and the same pulp specimen, correlating with the morphological appearance of the fibers. A large part of the fibers is fully accessible to enzymatic attack, but many fibers are not. Enzyme-substrate interaction between lignin peroxidase and residual lignin was evident: contrary to the two inert proteins, a great enrichment of the fibers with the enzyme was observed with lignin peroxidase.

Requirements for the Treatment of Effluents from Chemical Pulp Mills in the F.R.G.

In 1986, the 11 chemical pulp mills in the F.R.G. produced 350,00 t of bleached sulfite pulp. With the enactment of the so-called minimum requirements in 1982, general standards for the treatment of effluents were promulgated for this branch of industry. They comprise various measures, such as high-grade recovery of spent liquor including its evaporation and incineration, partial or total reuse of condensates from evaporation or reduction of their load by stripping, and mechanical treatment of total waste water. In view of the persisting high pollution levels of German rivers caused by pulp mills, more stringent standards reflecting the present state of the art will be implemented in 1991. This paper deals with these standards, covering the applicable in-plant and external abatement measures, such as extended cooking, substitution of elemental chlorine and biological treatment for decisive improvement of the chemical pulp mill effluent situation.

HOMOGENEOUS BUTYRATION OF CELLULOSE DISSOLVED IN DIMETHYL SULFOXIDE-FORMALDEHYDE SYSTEM

Bleached sulfite pulp was dissolved with formaldehyde in dimethyl sulfoxide, and the optimum condition was determined in terms of sufficient dissolution and prevention of degradation of cellulose. Homogeneous acetylation of the cellulose dissolved was examined, and the cellulose acetates witl a degree of substitution up to 2.4 were obtained in recovery yield ca. 80%. The preparation of the cellulose acetate with a degree of substitution close to 3.0 was inferred to be difficult with the present method. The cellulose acetates with a degree of substitution 2.0-2.4 was found to be easily soluble in ethyleneglycol monomethyl ether and ethyl lactate, and practically soluble in acetone. The solubility of the cellulose acetate was found to be slightly poorer than that of partially saponified cellulose acetate with a similar degree of substitution, prepared from cellulose triacetate, suggesting that the degree of polymerization of the acetate was higher than that of the partially saponified one. The cellulose acetate film prepared from the ethyleneglycol monomethyl ether solution was slightly yellowish transparent, and brittle, but was hard and had rather high tensile strength. The results indicate that the cellulose acetate obtained with the present method may have a possibility for commercial application.

HOMOGENEOUS ACETYLATION OF CELLULOSE DISSOLVED IN DIMETHYL SULFOXIDE-FORMALDEHYDE SYSTEM

Bleached sulfite pulp was dissolved with formaldehyde in dimethyl sulfoxide, and the optimum condition was determined in terms of sufficient dissolution and prevention of degradation of cellulose. Homogeneous acetylation of the cellulose dissolved was examined, and the cellulose acetates witl a degree of substitution up to 2.4 were obtained in recovery yield ca. 80%. The preparation of the cellulose acetate with a degree of substitution close to 3.0 was inferred to be difficult with the present method. The cellulose acetates with a degree of substitution 2.0-2.4 was found to be easily soluble in ethyleneglycol monomethyl ether and ethyl lactate, and practically soluble in acetone. The solubility of the cellulose acetate was found to be slightly poorer than that of partially saponified cellulose acetate with a similar degree of substitution, prepared from cellulose triacetate, suggesting that the degree of polymerization of the acetate was higher than that of the partially saponified one. The cellulose acetate film prepared from the ethyleneglycol monomethyl ether solution was slightly yellowish transparent, and brittle, but was hard and had rather high tensile strength. The results indicate that the cellulose acetate obtained with the present method may have a possibility for commercial application.

過酢酸気相標白したＢＳＰの強度特性について

In order to elucidate the mechanical properties of bleached sulfite pulp, NUSP and LUSP were bleached with peracetic acid (PA) in vapor phase under the following conditions : Chemicals addition on pulp, 10 to 32% ; DAISERU stabilizer addition on pulp, 0.018% ; pulp consistency, 33% ; temperature, 90°C ; pH 4 ; bleaching time, 60 min for NUSP and 30 min for LUSP. Viscosity of BSP thus obtained was 4 to 16 cp, and the brightness was 86 to 94% GE. Comparison between the sheet strengths and pentosan content or viscosity of BSP prepared under above conditions was also carried out. The results are summarized as follows : 1. NUSP and LUSP were more easily bleached than NUKP or LUK1 by PA-bleaching in vapor phase. Brightness of both SP, bleached with PA in vapor phase, was 5 to 8% GE higher than that of multistage-bleached SP at the equal pulp viscosity. 2. The decrease in tensile strengh, burst factor, tear factor and folding end. of linter pulp during PA- or multistage-bleaching was attributed to decrease viscosity of the pulp in a cupri ethylenediamine solution. On the other hand, sheet strengths of PA- or multistage-beached NSP and LSP at the equal freeness increased proportionally with increasing pentosan content in the bleached pulps, except folding end. of multistage-bleached NSP sheet. 3. The ellution pattern of gel filtration of hemicellulose, isolated from NSP with 5% KOH solution, was found to unchange hardly during multistage- or PA-bleaching in vapor phase. Whereas hemicellulose in LSP was partially degraded to lower molecular part during both bleaching. The lower molecular content of hemicellose in the PA-bleached LSP was more than that in the multistage-bleached pulp. 4. Tensile strength and burst factor of PA- or multistage-bleached pulp increased proportionally with increasing sheet density of each bleached pulp at the equal f reeness. The sheet strengths of PA- or multistage bleached KP were stronger than that of BSP at the equal sheet density. From the facts described above, it is assumed that the decrease of DP of polysaccharides in BSP is reduced the sheet strengths of the BP, and also, that the strengths are greater affected by the amounts of pentosan and lower molecular part of hemicellulose in the pulps.

Some physical properties of films made from cellulose dissolved in solutions of nitrogen dioxide in dimethylformamide

Water-soluble films of cellulose nitrate-nitrite were prepared by dissolving bleached sulfite pulp in a solution of nitrogen dioxide in dimethylformamide (DMF) at room temperature and heating the solution at 70°C for about 3 hr. Their water sorption, fine structure, and electrical properties were measured and compared with those of three other films—one water soluble (poly(vinyl alcohol)) and two water insoluble (cellophane and a film prepared from a cellulose solution in the nitrogen dioxide–DMF mixture and cast immediately after the cellulose had dissolved at room temperature). A comparison between the properties of water-soluble films and the poly(vinyl alcohol) film showed that the former had higher crystallinity, lower moisture absorption in the 0–80% relative humidity region, lower permittivity and a.c. conductance, and higher d.c. resistance. The DMF-cast water-insoluble film adsorbed less moisture than the cellophane film.

Water‐soluble cellulose derivatives prepared by the action of solutions of nitrogen dioxide in dimethylformamide

AbstractCellulose derivatives soluble in water and in dilute alkali were prepared by dissolving a bleached sulfite pulp in solutions of nitrogen dioxide in dimethylformamide (DMF) and heating at 70–90°C for 1–3 hr. No cellulose oxidation was detected. Nitrite esters and apparently also, nitrate esters, were formed with degrees of substitution (DS) ranging from 0.18 to 0.55 and with nitrogen contents ranging from 1.47 to 4.32%. Solution viscosities in water increased with increasing nitrogen content. The degree of polymerization (DP) decreased rapidly in the initial stages of the reaction followed by a slow, gradual decrease with increasing reaction times.

Studies of the graft copolymerization of methyl methacrylate by means of the photochemical reduction of ceric ion adsorbed on cellulosic materials

AbstractIt was observed that the rate of reduction of ceric ion adsorbed on cellulose was remarkably accelerated by irradiation with ultraviolet light, and this behavior depended upon the kind of cellulose. When the graft copolymerization of methyl methacrylate on cellulose with adsorbed ceric ion was carried out by irradiation with ultraviolet light, the percent grafting decreased for softwood, bleached sulfite pulp and increased for hardwood semichemical pulp. The average molecular weight of the grafts was observed generally to decrease. If it is assumed that the ceric ions, which are reduced at an accelerated rate in the early stages of reaction with SCP, do not participate in the graft formation, a relation is observed between the modified amount of reduced ceric ion and the number of grafted chains formed, and the molar ratios of these quantities are 12:1 without irradiation and 75:1 to 100:1 with irradiation. Even when the rate of reduction of ceric ion is accelerated, the increase in the number of grafted chains is found to be very small.

Hydrolysis of Pulp with Cellulase

Recently, cellulose hydrolytic enzyme, cellulase, has been provided in semi-commercial scale, and it is desired to find some uses. In this paper, to study the feature of the reaction, the phenomena of the hydrolysis of bleached sulfite pulp with commercial cellulase were compared with those with hydrochloric acid. The results were as follows : 1) The difference was shown between the amounts of the part resist to acid hydrolysis and that to enzymatic one. The former was more than 80%, and the latter was less than 70%. 2) The rate of enzymatic hydrolysis of the pulps, each yield being 81% and 55%, prepared with enzymatic treatment, were somewhat lower than that of original pulp. But, in the case of acid hydrolysis of the pulps pretreated with enzyme, two different results were obtained. When the pulp slightly pretreated with enzyme, the rate of hydrolysis decreased, but it increased when it was prehydrolysed up to a certain extent, as compared with that of the original pulp. 3) Nevertheless the shape of the distribution curve and the average DP of the pulp changed remarkably with acid hydrolysis, very small changes were merely observed when the pulp was treated with enzyme. 4) Whereas pulp fiber was changed easely into fine powder with acid hydrolysis, the changes of the fiber in length and width with enzymatic hydeolysis were very small.