Chemimechanical Pulp Research Articles

Pollutant characteristics from wastewater of poplar pre-conditioning refiner chemical alkaline peroxide mechanical pulping pretreated with Phanerochaete chrysosporium

The compositions of the organic pollutants of chemi-mechanical pulping wastewater were studied using Fourier transform infrared spectra and gas chromatography-mass spectrometry. The chemical oxygen demand (COD) was approximately 18110 mg/L, and the ratio of biological oxygen demand to COD (BOD5/COD) was approximately 0.17, due to low biodegradability. In this study, Phanerochaete chrysosporium was selected and the changes in bacterial culture time required to transform pulping wastewater and the metabolites present before and after pretreatment in the wastewater were identified. A decline in the components of the pulping wastewater was observed. Initially, 43 kinds of organic compounds were detected in the raw water. After 3 days of treatment, only 21 organic compounds were detected. Then, 7 days later, the organic pollutants in the waste amounted to only 7 organic compounds. Through the analysis of analysis of P-RC APMP pulping wastewater and that treated by Phanerochaete chrysosporium using GC-MS, the relative content of organic acids was 12.4%, in which phenylpropionic acid had the highest concentration of 11.3%. So, in the culture medium, phenylpropionic acid as the single carbon source can be completely degraded within 96 h.

Autohydrolysis prior to poplar chemi-mechanical pulping: Impact of surface lignin on subsequent alkali impregnation

Chemi-mechanical pulping, a typical high-yield pulping method, combined with autohydrolysis pretreatment prior to pulping is an efficient and value-added utilization method for biomass in pulp and paper industry. This study investigated the surface lignin changes of poplar sapwood chips in autohydrolysis pretreatment and their effect on the subsequent alkali impregnation for chemi-mechanical pulping. The results showed that the surface lignin content went up with the increase of autohydrolysis intensity, and that the existence of the surface lignin had nearly no impact on the subsequent alkali impregnation in making chemi-mechanical pulps (CMPs) compared to the volume porosity, which was validated by using the stepwise regression analysis. It can be further concluded that autohydrolysis can facilitate the subsequent alkali impregnation of the autohydrolyzed sapwood chips in making CMP, which would be of significance for the combination of biomass refinery and pulp and paper industry.

Fabrication of self-assembled polysaccharide multilayers on broke chemi-mechanical pulp fibers: Effective approach for paper strength enhancement

The present study was conducted to form polysaccharide-based multilayers of cationic starch (CS)/anionic starch (AS), and CS/carboxymethyl cellulose (CMC) on broke chemi-mechanical pulp (BCMP) fibers. It aimed to examine the buildup of CS/AS and CS/CMC polyelectrolyte multilayers (PEM) on the fibers surface, and explore the effects of PEM formation on the properties of the resulting papers. The assembly of PEM was analyzed by using zeta (ζ-) potential, water retention value (WRV), SEM micrographs, and paper properties such as thickness and strength. The results of ζ-potential inversions indicated successful constitution of PEM on the BCMP fiber surface by assembling CS/AS or CS/CMC multilayers. Further, larger ζ-potential variations occurred in depositing CS/CMC PEM, due to more charge of CMC, which presumably formed a layer with greater potential of absorption. Based on the SEM images, the surface of PEM-treated fibers was rougher, compared to the untreated fibers due to the coating with starch. Furthermore, the PEM fabrication resulted in creating fibers with higher degree of WRV, which was consistent with the significant improvement of the sheet strengths. Finally, the strength enhanced papers made from PEM-treated fibers with tensile index of about 37.33 ± 1.47 N m/g vs 22.24 ± 1.23 N m/g or 11.60 ± 0.57 N m/g for the papers made from original CMP and untreated BCMP fibers, respectively, may diminish the challenges related to web breaks in the paper machine conveying BCMP broke fibers.

Effect of sulfonation treatment concentration on the properties of mulberry chemi-mechanical pulp

Sulfonation chemimechanical pulping (SCMP) of mulberry stalk was studied with different treatment concentrations. The resulting mulberry SCMP pulp contained different content of sulfonic acid groups depending on the concentrations. The brightness, tensile index, and folding resistance of mulberry SCMP pulp increased with the increasing concentration of sulfonation treatment, but the thickness decreased with increasing concentration. There was either a linear or a non-linear relationship between the content of sulfonic groups and the pulp physical properties. The mass average length of mulberry SCMP pulp was 0.66 mm, the fiber width was 16.4 μm, and the content of fine fibers was 20.6%.The mulberry extract and lignin dissolved, and part of soluble lignin may have been deposited on fiber surface in the process of SCMP pretreatment. There were almost no changes to the cellulose crystalline structure.

Improved permeability of autohydrolyzed poplar sapwood against sodium hydroxide for CMP production

AbstractPoplar sapwood chips were autohydrolyzed at three severity levels and subsequently treated with alkali for the production of chemi-mechanical pulp (CMP). The aim was to study the variation of the principal pathways for sodium hydroxide solution and the alkali concentration and distribution inside the autohydrolyzed chips as a function of autohydrolysis (AH) severity. The tyloses in the vessels and some pit membranes were partly dissolved after AH, while the skeletal structure of the fiber and vessel cell walls remained intact. AH had a positive influence on the diffusion and the uniform distribution of NaOH solution both in the axial and radial direction of the chips, but the axial direction was more favored than the radial one.

Improved diffusivity of NaOH solution in autohydrolyzed poplar sapwood chips for chemi-mechanical pulp production

This work investigated the changes in the physical structure of autohydrolyzed poplar sapwood chips and the effect on the subsequent alkali liquor diffusion properties for chemi-mechanical pulping (CMP). An alkali impregnation process was conducted by using the autohydrolyzed poplar sapwood with different levels of autohydrolysis intensity. The results showed that the volume porosity, water constraint capacity, and saturated water absorption of the autohydrolyzed poplar sapwood chips increased. Also, the effective capillary cross-sectional area (ECCSA) in the radial direction and the diffusion coefficients of NaOH solution in both the radial and axial directions all increased. Autohydrolysis pretreatment enhanced the alkali liquor diffusion properties in poplar sapwood chips, and the diffusion coefficient was increased more greatly in the radial direction than that in the axial direction.

EFFECTS OF BEATING ON THE CHARACTERISTICS OF MALAYSIAN DURIAN (DURIO ZIBETHINUS MURR.) RIND CHEMI-MECHANICAL (CMP) PULP AND PAPER

The effects of beating on the characteristics of pulp and paper derived from durian rind under chemi-mechanical pulping (CMP) method were investigated. All process and characteristic tests were conducted according to Malaysian International Organization for Standardization (MS ISO) and Technical Association of the Pulp and Paper Industry (TAPPI). The unbeaten durian rind CMP pulp (control pulp) was beaten by using PFI mill at three (3) different beating levels; 1000, 2000 and 3000 revolutions. It was found that durian rind CMP pulp drainage time was increased (longer time) and freeness level was decreased as the beating revolutions were increased compared to the control pulp. The result shows that paper bulk density and overall mechanical characteristics (tensile index, tear index, burst index and folding no.) of 60 gsm durian rind CMP hand sheets were increased with the increment of beating revolutions.

Enzymatic Assisted Ultrasonic Pretreatment’s Effect on Poplar Pulp Properties

A combined process consisting of an enzymatic pretreatment of small poplar wood chips, followed by an ultrasonic treatment was proposed and performed. Under the ultrasonic action of cavitation, thermal, and mechanical effects, the two processes of pulping and bleaching can be completed in one procedure. Before the ultrasonic treatment assisted pulping, an enzyme pretreatment was used to destroy the bonds between the cellulose, hemicellulose, and lignin to make the subsequent ultrasonic treatment exhibit higher selectivity and efficiency. This provided a poplar ultrasonic assisted pulp (PUP) with a 75% yield. A further analysis of the pulp, utilizing a scanning electron microscope (SEM), showed the fine fibrillation degree of the fiber surface of PUP was comparable to the traditional poplar chemimechanical pulp (PMP) and poplar chemical pulp (PCP). Thermogravimetric analysis and Raman analysis showed that the final residue obtained from the PUP was 20%. In addition, a decorative base paper was successfully made using the poplar ultrasonic pulp, and the physical properties reached or exceeded the industry standard of decorative base paper.

EFFECTS OF TOTAL CHLORINE FREE (TCF) BLEACHING ON THE CHARACTERISTICS OF CHEMI MECHANICAL (CMP) PULP AND PAPER FROM MALAYSIAN DURIAN (DURIO ZIBETHINUS MURR.) RIND

The effects of bleaching process on the characteristics of pulp and paper produced from durian rind under chemi‑mechanical pulping (CMP) method were investigated. All process and characteristic tests were conducted according to Malaysian International Organisation for Standardization (MS ISO) and Technical Association of the Pulp and Paper Industry (TAPPI). Three (3) stages of peroxide (P‑P‑P) bleaching sequence through the Total Chlorine Free (TCF) bleaching process were applied to the unbeaten and unbleached durian rind CMP pulp. Bleached CMP durian rind pulp drainage time (32s) decreased (faster) and CSF freeness level (172.50ml) increased as compared to a control pulp. It was obtained that overall optical (brightness (66.36 %)) and mechanical characteristics (tensile index (38.33 Nm/g), tearing index (7.56 mN.m2/g), bursting index (2.42 kPa.m2/g), and number of folds (43)) of durian rind CMP 60 gsm paper sheet improved as the TCF bleaching process was applied to the unbleached CMP durian rind pulp.

Preparation of Cationic CMP and Softwood Long Fibers as Strength-Enhancing Additive to CMP Pulp

Compared to chemical pulp, mechanical and chemi-mechanical pulps (CMP) are limited in regards to the manufacturing of high quality paper. Chemical additives are an effective way to enhance the properties of paper; however, the effectiveness depends on the additive type and dosage. The utilization of cationized natural polymers has been shown to offer a promising solution. In this study, softwood long fiber (SLF) and CMP were cationized by 3-chloro-2-hydroxypropyl-trimethylammonium-chloride (CHPTAC), and the effects of cationization on the properties of CMP pulp were studied. Cationization was characterized by FTIR and the nitrogen content, and its effect on the CMP properties was evaluated through mechanical tests and fines retention. Cationization at low and moderate levels and in higher mixing rates improved the mechanical properties of CMP. Compared to cationized CMP, the addition of cationized SLF (CLF) improved the strength and fines retention properties. The CLF application to CMP at a CHPTAC dosage of 5% increased the tensile, burst, and tear strengths by 66.4%, 100%, and 3.6%, respectively. The cationized SLF increased the fines retention by 12.7%.

Adsorption Mechanism of Anionic Groups Found in Sulfonated Mulberry Stem Chemi-Mechanical Pulp (SCMP) for Removal of Methylene Blue Dye

The anionic groups (AGs) present in mulberry stem sulfonated chemi-mechanical pulp (SCMP) were studied relative to the adsorption of methylene blue (MB) dye. Adsorption isotherm experiments were carried out for the unbleached pulp, and for pulp that had been subjected to hydrogen peroxide (H2O2) bleaching. AGs present in the pulps appeared to govern the adsorption of MB. MB adsorption kinetics were evaluated for the bleached pulp. The methylene blue adsorption by SCMP, made from mulberry stems, conformed to the Langmuir adsorption model, which is consistent with a monolayer adsorption process. The adsorption thermodynamics showed that the adsorption process was spontaneous and exothermic. A pseudo-second order kinetic model described the adsorption mechanism of MB by the SCMP made from mulberry stems.

Improving the efficiency of hydrogen peroxide bleaching of chemimechanical pulp by continuous replenishment of bleaching chemicals

Hydrogen peroxide (H2O2) is commonly used to bleach chemimechanical pulp. A decrease in the concentrations of the bleaching reagents throughout the bleaching process results in low bleaching efficiencies. In this study, chemical solutions were continuously added into the pulp slurry during the bleaching process to maintain constant concentrations of H2O2 and total alkali in the bleaching system to improve bleaching efficiency. The results showed that when the H2O2 and total alkali concentrations were maintained at 4.5 g/L and 0.79 g/L, respectively, for 50 min, the bleaching efficiency reached 16.79 (Δ% ISO brightness/Δ% H2O2 consumed [on ovendry pulp]), which was significantly higher than 7.38 obtained by using the high-consistency bleaching method. The results confirmed that continuous replenishment of chemical solutions into the bleaching system to maintain the constant chemical concentrations improved the efficiency of H2O2 bleaching of the chemimechanical pulp.

Characteristics of Pollution from Waste Liquor of Poplar Pre-Conditioning Refiner Chemical Alkaline Peroxide Mechanical Pulping

The molecular weight distribution and composition of organic pollutants from chemi-mechanical pulping waste liquor was studied using ultra-filtration, Fourier transform infrared spectra, and gas chromatography-mass spectrometry. The concentration of dissolved chemical organic compounds was approximately 1.81 × 104 mg·L-1. In addition, the wastewater had poor biodegradability. The chemical oxygen demand (COD) was primarily composed of small molecular organic pollutants, and the larger pollutants in the waste liquor were its primary source of color. The data indicated that there were chromophoric and auxochrome groups in the waste liquor. The waste liquor contained 38 types of organic pollutants, which were aromatic compounds, including phenols, ketones, alcohols, and fatty acids.

Hemicelluloses removal in autohydrolysis pretreatment enhances the subsequent alkali impregnation effectiveness of poplar sapwood

This work is aimed at investigating the influence of changes in the content of hemicelluloses of the autohydrolyzed poplar sapwood on the subsequent alkali impregnation for chemi-mechanical pulping (CMP). An alkali impregnation process was conducted using the autohydrolyzed poplar sapwood with different content of hemicelluloses as raw materials. The results showed that both the amount of NaOH consumption and swelling degree of poplar sapwood increased with the removal of hemicelluloses, thus enhancing the alkali impregnation effectiveness. The hemicelluloses removal can also shorten the alkali impregnation time for the autohydrolyzed poplar sapwood to achieve the similar impregnation effectiveness of unautohydrolyzed poplar sapwood. All of these can be attributed to the fact that the hemicelluloses removal would result in the exposure of more free hydroxyl groups on the cellulose and an increase in the porosity of the fiber cell walls.

Effects of Ozone and Nanocellulose Treatments on the Strength and Optical Properties of Paper Made from Chemical Mechanical Pulp

This effects of ozone and nanocellulose treatments were studied relative to the optical and strength features of chemical mechanical pulp (CMP) papers. An ozone treatment was performed at room temperature, and then nanocellulose was added. Sixty-gram handmade papers were made, and their physical, mechanical, and morphological properties were studied using X-ray diffraction (XRD) and scanning electron microscopy (SEM). With the ozone treatment, changes in the optical features were not significant at the 95% level; however, the addition of nanocellulose led to significant changes: the tensile strength, burst strength, air resistance, opacity, and brightness increased by 14.1%, 15.9%, 34.8%, 2.8%, and 3.2%, respectively, in comparison with the control sample. The enhancement with nanocellulose reduced the tear strength, coarseness, and yellowness by 15.7%, 12.9%, and 7.6%, respectively, compared with the control sample. The crystallinity of neat nanocellulose was 65.59%, while the crystallinities with the use of 5% to 10% nanocellulose were 72.41% and 62.26%, respectively. The SEM results indicated that using a 10% nanocellulose treatment led to the reduction of the CMP paper’s porous character.

Investigation on physical and mechanical properties of pulp–plastic composites from bagasse

ABSTRACTHigh-density polyethylene (HDPE), bagasse fibers treated by four pulping processes (AS-AQ (alkaline sulfite anthraquinone), SODA-AQ (soda anthraquinone), MEA (monoethanolamine) and chemical–mechanical pulping (CMP)), three levels of nano-SiO2 (0, 2, and 5 wt%), and maleic anhydride polyethylene as coupling agent were used to produce pulp–plastic composites (PPCs) by injection molding. The physical and mechanical properties of corresponding composites were evaluated according to ASTM standards. The results showed that compared to untreated bagasse/HDPE composite, the addition of bagasse pulp fibers increased significantly the mechanical properties such as tensile strength and modulus, flexural strength and modulus, and hardness. The chemical pulps-reinforced composites showed better mechanical strengths than that of CMP-reinforced composites, but in some properties, CMP pulp composites have comparable results to the chemical pulp-reinforced composites. Natural fibers (untreated and treated) increased water absorption and thickness swelling of composites compared to pure HDPE. The addition of nano-SiO2 particles showed both increasing and decreasing trends on physical and mechanical properties ofPPCs.

Optimization of transmission system design based on genetic algorithm

Transmission system is a crucial precision mechanism for twin-screw chemi-mechanical pulping equipment. The structure of the system designed by traditional method is not optimal because the structure designed by the traditional methods is easy to fall into the local optimum. To achieve the global optimum, this article applies the genetic algorithm which has grown in recent years in the field of structure optimization. The article uses the volume of transmission system as the objective function to optimize the structure designed by traditional method. Compared to the simulation results, the original structure is not optimal, and the optimized structure is tighter and more reasonable. Based on the optimized results, the transmission shafts in the transmission system are designed and checked, and the parameters of the twin screw are selected and calculated. The article provided an effective method to design the structure of transmission system.

Ultrasound-assisted Xylanase Treatment of Chemi-Mechanical Poplar Pulp

Xylanase treatment can be an environmentally friendly way to improve the formability and drainability of chemi-mechanical pulp (CMP). Improvements in xylanase treatment efficiency are possible with application of an ultrasonic wave via the cavitation effect. Results showed that the specific surface area (SSA) of the combined treated pulp increased by 14.6% at an ultrasonic treatment of 30 min and xylanase dosage of 10 U/g, in comparison to xylanase treatment alone. Also, the drainability of xylanase-treated pulp increased from 450 to 500 mL, and it further increased to 775 mL with ultrasonic-assisted xylanase treatment. Morphological characterization of pulps showed an enhanced fibrillation for the combined treatment, as shown by scanning electron microscope (SEM) images. In addition, the dimensions of treated fibers were negligibly affected.

Mixing Bleached White Poplar and Wheat Straw Chemimechanical Pulps to Improve the Mechanical and Optical Characteristics

The aim of this study was to determine the optimum combination of wheat straw and white poplar (P. alba) chemimechanical pulps (CMPs) for producing newsprint paper. The CMP was prepared separately from the two raw materials. Cooking conditions included 10%, 12%, and 14% chemical charge based on w/w oven dry raw materials, maximum cooking temperatures of 120, 140, and 160 °C, and cooking time of 45 min. Hydrogen peroxide was used for bleaching the selected pulp. The results indicated that screened pulp yields were in the range of 54.3% to 61% and 80.9% to 85.9% for 18 cooking trials of wheat straw and white poplar, respectively. Handsheet brightness reached up to 52.9% and 61.9% for wheat straw and white poplar, respectively. The highest breaking length and burst index were related to CMP produced from 25% white poplar/75% wheat straw pulp blend. The best tear index was obtained using a mixture of 50% white poplar and 50% wheat straw pulp. Averages of breaking length, burst and tear indices ranged between 4.61 and 3.80 km, 2.31 and 2.55 kPa•m2/g, and 7.29 and 11.1 mN•m2/g, respectively. The strength properties of handsheets were higher than those reported for commercial newsprint except the breaking length of 50%/50% blend.

Characteristics of Linerboard and Corrugated Medium Paper Made from Durian Rinds Chemi-mechanical Pulp

In recent years, there has been tremendous growth of interest in the utilization of non-wood based material to support the insufficient raw materials availability for the pulp and paper industry. Therefore, this study was conducted to investigate the characteristics of 120 gsm linerboard and corrugated medium paper made from unbeaten durian rinds chemi-mechanical (CMP) pulp. The linerboard and corrugated medium paper were prepared and tested according to Malaysian Standards / International Organization for Standardization (MS ISO) and Technical Association of the Pulp and Paper Industry (TAPPI) standard methods. Based on the burst index (2.03 kPa.m 2 /g), RCT (1.97 N.m 2 /g) and CMT (129N), the linerboard and corrugated medium from CMP durian rind pulp have shown a good potential as an alternative raw material for papermaking and comparable with other types of wood and non-wood based papers as well as current commercial papers.