Chemimechanical Pulp Research Articles

Improving the bleachability of whole cotton stalk chemimechanical pulp with depectinization agents

The effects of pretreatment agents on pectin removal and chemical compositions in cotton stalk bark were studied. The results showed that the reaction rates of the depectinization agents reacting w ...

Mg(OH)2-based hydrogen peroxide bleaching of CMP pulps at high consistency

The objective of this study was to investigate the bleaching performance of a Mg(OH)2-based hydrogen peroxide process at a high consistency. In this work, an industrially produced chemimechanical pulp (CMP) was bleached via Mg(OH)2- or NaOH-based hydrogen peroxide processes at 10% and 25% consistencies. The results showed that the pulp bleached under the conditions of 1.5% Mg(OH)2 and 3% H2O2 at 25% consistency had a similar brightness to, a lower yellowness index, and a higher opacity than the pulp produced under the conditions of 2.1% NaOH, 3% Na2SiO3, and 3% H2O2 at the same consistency. The temperature (70 ºC) and time (150 min) of the bleaching were the same for both processes. Under the conditions stated above, the Mg(OH)2-based process had a higher yield than the NaOH-based process did. The bleaching effluent of the Mg(OH)2-based process had a higher residual H2O2, but a lower Chemical Oxygen Demand (COD) load and turbidity, compared with that of the NaOH-based process. However, the strength properties and water retention value (WRV) of the pulp bleached via the Mg(OH)2-based process were lower, while its bulk was higher than those of the pulp bleached via the NaOH-based process.

Sulfonated Chemi-Mechanical Pulp of Cotton Stalk and Bleaching

The influence of operational variables in the Sulfonated Chemi-mechanical pulp (SCMP) of cotton stalk was studied, and the hydrogen peroxide bleaching sequence was carried out. The major factors, such as sulfite sodium charge (calculated as Na2SO33%, 6%, 9%or 12%on oven-dry cotton stalk), active alkali charge (calculated as NaOH 2%, 4%, 6%or 8%on oven-dry cotton stalk) and the maximum temperature (110°C, 130°C or 150°C) was investigated. The result shows that: the pulp physical property was influenced significantly by sulfite sodium and active alkali charge, at an increasing tendency with above factors. The optimal chemical treatment cooking conditions could be proposed as follows: sulfite sodium charge 9%, active alkali charge 2%, maximum temperature 130°C and liquor ratio 4:1. What’s more, the single H2O2bleaching sequence was employed, which can provide pulps with brightness 58.0%ISO.

Roles of short amine in preparation and sizing performance of partly hydrolyzed ASA emulsion stabilized by Laponite particles

Alkenyl succinic anhydride (ASA) is an internal sizing agent used to hydrophobize paper and paperboard in paper making process. Partly hydrolyzed ASA (hereinafter referred to as PH-ASA) emulsions can be stabilized by Laponite and short amines such as ethylamine, n-propylamine and n-butylamine. It is found that the short amines may improve the affinity of Laponite particles to PH-ASA, favoring PH-ASA emulsification, forming emulsion of high stability and small droplets. It is further observed that the sizing development of the PH-ASA on bleached chemi-mechanical pulp (BCTMP) is promoted when aluminum sulfate is added. Amine with longer carbon chain is more efficient both in promoting PH-ASA emulsification and in its sizing process. The amine molecules adsorbed on Laponite are more effective in stabilizing PH-ASA emulsions while the free amine in the dispersion work more efficiently in promoting sizing performance through a mechanism of accelerating the reaction between hydrolyzed ASA and aluminum sulfate. However, the PH-ASA emulsions lose most of their sizing effect by hydrolysis within 60 min.

Characterization of bamboo SCMP alkaline extractives and the effects of peroxide bleaching

The compositions of alkaline extractives in bamboo sulfonated chemi-mechanical pulps (SCMP) were analyzed by UV spectroscopy and gas chromatography-mass spectrometry (GC-MS), and their effects on peroxide bleaching were studied. The extractives were composed of short-chain aliphatic compounds, phenols, and fatty acids, of which phenols were the major components. The amount of extractives was increased with the dosage of NaOH, and correspondingly, the bleachability of the extracted pulp was improved. When 3.5% NaOH was used, the brightness gain was 5.83%ISO, and the post-color (PC) number was decreased by 55.7%. The phenol compounds, which might easily generate conjugated structures, may play an important role in bleachability of bamboo SCMP and brightness stability of pulp.

Reduction of the recalcitrant COD of high yield pulp mills effluents by AOP. Part 1. Combination of ozone and activated sludge

The aim of this work was to study the effect of ozone, either alone or combined with an activated sludge system, on the reduction of the recalcitrant COD in the effluent of a chemimechanical pulping (NaOH -Na2SO3) integrated mill. Several alternative schemes involving ozonation were tested on liquors and effluents of the pulp mill, and on two kinds of effluents were taken at different points of an activated sludge pilot plant. The largest decrease in COD was 33%, whereas that in aromatic compounds (absorbance at 232.5 nm) was of 73%. The most obvious result of the ozone treatment was effluent decolorization. It was not possible to use ozonation as tertiary treatment, as ozone was necessary to treat the BOD generated, and therefore the effluent must necessarily pass through a biological treatment. With a scheme including an intermediate ozonation between two secondary treatments (post-activated sludge and pre-aeration lagoon), the maximum reductions achieved were of 70% in COD, of 93% in aromatics, and of 96% in color. The limits of COD allowed by the environmental regulations (<250 mg/L) could be achieved with the following stages: 1) primary clarifier, 2) activated sludge system, 3) ozonation, 4) aeration lagoon, and 5) stabilization lagoon.

Effect of Compatibilizer on Mechanical, Morphological, and Thermal Properties of Chemimechanical Pulp-reinforced PP Composites

Mechanical, morphological, and thermal properties of injection molded, chemimechanical pulp (CMP)-reinforced polypropylene (PP) composites were investigated as a function of different concentrations of maleic anhydride-grafted PP. It was found that tensile strength and failure strain and the notched impact strength increased progressively with increasing compatibilizer content, whereas the addition of any concentration of compatibilizer did not alter the tensile modulus. Scanning electron microscopy — micrographs of tensile fracture surfaces of composites with 2% compatibilizer indicated very little fiber pullout and many fractured fibers. The thermal stability of pure PP was found to be higher than that of CMP-reinforced PP composites. With addition of compatibilizer, the thermal stability of the composites was slightly increased. The activation energy was determined to describe the energy consumption of the initiation of the thermal degradation process. The activation energy of the composites was found to depend on the dispersion and interfacial adhesion of CMP and PP matrix.

The Application of Extruder in Chemical-Machinery Pulping Production and the Influence of the Wastewater Biochemical Treatment

Traditional chemical-machinery producing mainly took the refiner as the primary refining equipment. Extrusion pulping was the reformation of traditional refining pulping. The different equipments and processes resulted in the different characteristics of wastewater inevitably. This article aimed to compare the characteristics and biochemical treatment methods between conventional chemical-mechanical pulping and extrusion pulping, and then discuss the biochemical treatment advantages of extrusion pulping wastewater. The result shows that: the wastewater from the extrusion pulping has lower concentration of tiny fiber, load suspended matter, wastewater temperature and effluent discharge. And thus make a simpler process, a lower cost and a better effect of the wastewater treatment.

The influence of ultrasonic treatment on the bleaching of CMP revealed by surface and chemical structural analyses

Effects of ultrasonic pretreatment on the bleaching of chemimechanical pulp (CMP) fiber of triploid Chinese white Poplar were investigated. Before single-stage hydrogen peroxide bleaching, CMP was sonicated at 1.5% pulp consistency and 50oC for 20min with 90% amplitude and 20s pulse; these conditions showed the most favorable effect of a 3.5% ISO increase of brightness, reaching a final value of 80.2% ISO. The benefit may be because the ultrasound can accelerate heterogeneous reactions, which arise from the impingement of microjets and shockwaves on the solid surface, which are then capable of inducing striking changes in surface morphology, composition, and reactivity. To prove the theory, the surface structure and surface morphology were investigated by SEM and AFM, and the crystalline structure and characteristics of the cellulose in terms of XRD and FT-IR were also evaluated.

THE INFLUENCE OF ULTRASONIC TREATMENT ON THE BLEACHING OF CMP REVEALED BY SURFACE AND CHEMICAL STRUCTURAL ANALYSES

Effects of ultrasonic pretreatment on the bleaching of chemimechanical pulp (CMP) fiber of triploid Chinese white Poplar were investigated. Before single-stage hydrogen peroxide bleaching, CMP was sonicated at 1.5% pulp consistency and 50oC for 20min with 90% amplitude and 20s pulse; these conditions showed the most favorable effect of a 3.5% ISO increase of brightness, reaching a final value of 80.2% ISO. The benefit may be because the ultrasound can accelerate heterogeneous reactions, which arise from the impingement of microjets and shockwaves on the solid surface, which are then capable of inducing striking changes in surface morphology, composition, and reactivity. To prove the theory, the surface structure and surface morphology were investigated by SEM and AFM, and the crystalline structure and characteristics of the cellulose in terms of XRD and FT-IR were also evaluated.

The effect of combination enzymatic and advanced oxidation process treatments on the colour of pulp and paper mill effluent

The efficiency of advanced oxidation processes (AOPs), enzymatic treatment and combined enzymatic/AOP sequences for the colour remediation of soda and chemimechanical pulp and paper mill effluent was investigated. The results indicated that under all circumstances, the AOP using ultraviolet irradiation (photo‐Fenton) was more efficient in the degradation of effluent components in comparison with the dark reaction. It was found that both versatile peroxidase (VP) from Bjerkandera adusta and laccase from Trametes versicolor, as pure enzymes, decolorize the deep brown effluent to a clear light‐yellow solution. In addition, it was found that in the laccase treatment, the decolorization rates of both effluents were enhanced in the presence of 2, 2’‐azinobis (3‐ethylbenzthiazoline‐6‐sulfonate), while in the case of by VP, Mn+2 decreased the efficiency of the decolorization treatment. The concomitant use of enzymes and AOPs imposes a considerable effect on the colour remediation of effluent samples.

Canola straw chemimechanical pulping for pulp and paper production

Non-wood is one of the most important raw materials for pulp and paper production in several countries due to its abundance and cost-effectiveness. However, the pulping and papermaking characteristics of canola straw have rarely been investigated. The objective of this work was to determine the potential application of canola straw in the chemimechanical pulping (CMP) process. At first, the chemical composition and characteristics of canola straw were assessed and compared with those of other non-woods. Then, the CMP pulping of canola straw was conducted using different dosages of sodium sulfite and sodium hydroxide. The results showed that, by applying a mild chemical pretreatment, i.e., 4–12% (wt.) NaOH and 8–12% (wt.) Na 2SO 3, in the CMP pulping of canola straw, the pulp brightness reached almost 40%ISO, and the strength properties were comparable to those of bagasse CMP and of wheat straw CMP. The impact of post-refining on the properties of canola straw CMP was also discussed in this work.

Color remediation of chemimechanical pulping effluent using combination of enzymatic treatment and Fenton reaction

This research investigated the efficiency of Advanced Oxidation Processes, Enzymatic treatment, and combined enzymatic/AOPs sequences on color remediation of CMP pulp and paper mills effluent. Regarding enzymatic treatment two kinds of fungal enzymes; Laccase (EC: 1.10.3.2) from Terametes Versicolor and Versatile Peroxidase (EC: 1.11.1.7) from Bjerkandera adusta were chosen and applied. Also, the effect of external mediator on the enzyme based degradations was studied. It was found that both VP from Bjerkandera adusta and Laccase from Terametes versicolor decolorized the deep brown effluent to a clear light yellow solution. It has been found that, concomitant use of enzymes and photo-Fenton process produces a considerable effect on color remediation. The data analysis of sequence treatment indicated that, chemical treatment after the enzymatic stage (photo-Fenton as a post treatment unit) yield a better performance for the CMP effluent.

Tensile Properties and Thermal Analysis of Chemimechanical Pulp-reinforced HDPE Composites

The tensile and thermal properties of chemimechanical pulp/high-density polyethylene composites made using virgin high-density polyethylene as the matrix polymer, chemimechanical pulp as reinforcing fiber, and maleic anhydride grafted polyethylene as compatibilizing agent were examined by assessing the tensile properties and thermogravimetric analysis. The results indicated that 2% compatibilized composites and uncompatibilized composites exhibited the highest and the lowest tensile strength values, respectively, while the tensile modulus is partially independent of compatibilizing agent. Using maleic anhydride grafted polyethylene increases composites’ failure strain and tensile energy absorption as well. Based on the TGA analysis during the manufacturing of the composites, blending and injection temperatures should be less than 230°C to prevent the chemimechanical pulp from decomposition.

Photodegradation of Acidolysis Lignin from BCMP

A mild acidic dioxane extraction method was employed to isolate lignin from hardwood bleached chemimechanical pulp (BCMP). The isolated lignin was then purified and undergone elemental analysis. To study the photodegradation behavior, the lignin samples were impregnated onto the Whatman filter papers and irradiated with UV light for various periods. The photolyzed lignin was then recovered and analyzed by 1H-NMR spectroscopy. Phenylpropane-based formula (C9) of CMP pulp lignin and the photolyzed samples were then established with elemental analysis and 1H-NMR spectroscopy data. The results indicated that the benzaldehyde and benzoic acid type compounds were the main photodegradation products of BCMP lignin. The lignin photodegradation probably involved the degradation of phenylcoumaran units. Irradiation also increased the phenolic hydroxyl group content and decreased that of methoxyl groups, due to demethoxylation. The degrees of aromatic ring condensation were increased upon continuing the irradiation time, which imples the formation of condensed structures in photolyzed lignin.

Kinetics of Hydrogen Peroxide Brightening of Western Red Cedar (Thuja plicata Donn) CTMP

The use of western red cedar mechanical pulp is limited by its very low brightness. This article presents the kinetic expressions for hydrogen peroxide brightening of western red cedar chemimechanical pulp. The significance of the results for the reaction mechanism and for brightening under practical conditions is discussed. The kinetics of peroxide brightening of western red cedar chemimechanical pulp was monitored at the three absorption maxima—357 nm, 457 nm, and 550 nm—in the UV-visible spectra. The reaction order with respect to hydrogen peroxide was around 1 at all three wavelengths. The reaction order with respect to chromophores was approximately 2.4 at the higher wavelengths and 5 at 357 nm. The kinetic equations were successful in predicting brightness values obtained under practical conditions.

Modeling hydrogen peroxide bleaching to predict optical properties of bleached hardwood CMP

Due to the variations in opacity and brightness of peroxide bleached pulp at Mazandaran Wood and Paper Industries Company (MWPI), empirical models were developed to predict chemimechanical pulp (CMP) brightness and opacity from peroxide bleaching conditions and to drive the optimum operating conditions. To overcome the inconsistency problem, a multi-variate regression analysis method was used for model building. The models were then validated using a new data set from the bleach plant at MWPI, assessing the models’ predictive ability and performance. The results show that there is a relationship between bleaching variables and such dependent variables as pulp brightness and opacity. In addition to the hydrogen peroxide charge and pulp initial brightness, the initial opacity had a significant reverse effect on the final CMP brightness. It was also found that the concentration of total Na+ in the CMP tower was the most important variable affecting the final pulp opacity. The validation results demonstrated that these models can be employed as useful tools for process optimization purposes.

Discoloration of mechanical and chemimechanical pulps: Influence of wood raw material, process and ageing method

The change in colour of a wide range of unbleached and bleached high-yield pulps was assessed using the CIELAB colour system. The influence of ageing method, pulping process and wood raw material i ...

Synergistic effects between chemical mechanical pulps and chemical pulps from hardwoods

Chemical pulps and chemical mechanical pulps from different hardwoods were compared for intrinsic and other pulp properties. Comparisons were made separately and in combination with these two types of pulps. The results showed that hardwood chemical mechanical pulps, such as preconditioned refiner chemical alkaline per-oxide mechanical pulp (P-RC APMP), can be developed to be as strong as chemical pulps, and have higher tensile at the same density, or higher bulk at the same tensile, compared with the chemical pulps. When combining pulps from the two processes, addition of certain percentages of hardwood chemical mechanical pulps to chemical pulp improved pulp intrinsic properties, and the resulting pulp blends had higher fiber bonding strength (tensile and tensile energy absorption) than the sum of weighted contributions from the individual components. This synergistic effect between the chemical and the chemical mechanical pulps may be used to improve papermaking processes and their paper and paperboard products.

Application of improved chemical–mechanical pulp from poplar wood in the packing paper composition

Populus deltoides variety Onda wood was used for obtaining of improved chemical–mechanical pulp (CMP) under laboratory conditions by preliminary treatment of wood chips with three types of enzymes, such as lignin peroxidase, manganese peroxidase and laccase, produced by Phanerochaete chrysosporium strain 1038.