Bleached Hardwood Kraft Pulp Research Articles

Beverage Coaster Paper - A Protective Paper Grade Development

Beverage coaster paper represents a specialty paper grade, which has its origin in the late 1880s. Its primary function is to serve as a barrier between the beverage and the table surface by soaking up the condensing water of the cold beverage and protect the wooden table surface as well as the customer from droplets of the condensing water.
 A beverage coaster grade was developed utilizing thermos mechanical pulp, bleached softwood and bleached hardwood Kraft pulp. Manufactured on a 48-inch (1219 mm) wide small commercial Fourdrinier paper machine with an oven dry basis weight basis weight of 473.6, and thickness of 886 µm.
 The water absorbance achieved a value 784 g/m² for the top side and 693 g/m² for the wire side of the paper. The smoothness value was 2734 ml/min for the top and 2784 ml/min for the wire side
 The burst index was measured at 0.56 kPa*m²/g, a tear index of 14.68 mNm²/g for the machine direction and 10.78 mNm²/g for the cross machine direction.
 The manufactured beverage coaster paper had no visible signs of dirt and a yellowish white color, an opacity a value of 100%, a brightness of 79.14% and a whiteness of 54.76%. The yellowish white colour had an 95.24% value for the L*, -1.62 for the a*, and 7.23 for the b*.

Development of Membrane Filter for Water Treatment Using Anionic and Cationic Cellulose Nanofibers

This study examined the effect of cellulose nanofiber (CNF) type on the performance of ion absorbing membrane filters made of anionic and cationic CNFs. Four types of anionic and cationic CNFs were made by beating, micro-grinding, carboxymethylation and quaternization using hardwood bleached kraft pulp (Hw-BKP): refining-CNF (RE-CNF), carboxymethylated CNF (CM-CNF), surface-modified CNF with cationic poly-DADMAC (pD-CNF), and quaternized CNF (Q-CNF). The membrane filters were composed of two-layers: One layer was made of anionic CNF and poly-aminiamide-epi-chlorohydrin (PAE) and the other layer was made of cationic CNF. The membrane filter was produced by vacuum filtration and the use of two CNF slurries. In addition, the capacity to remove Fe and Cl ions from the water was analyzed by carrying out high-pressure filtration experiments with a 500 ppm concentration of the Fe and Cl standard solutions respectively, using the same methods as the previous study.BRFour types of CNFs were sufficiently fibrillated at the nano-level and had electrostatically intended zeta-potential. The CM-CNF, which had a strong negative zeta-potential, was effective in the adsorption of Fe ions, and the Q-CNF, which was strong in cationic property, was effective in the adsorption of Cl ions. Therefore, it was concluded that cationic Q-CNF and anionic CM-CNF could be effectively utilized for the manufacture of a membrane filter to remove metal and anionic ions from water simultaneously.

Effect of Temperature of Tetraethylammonium Hydroxide/Urea/Cellulose Solution on Surface Tension and Cellulose Bead Size

Effects of temperature of the tetraethylammonium hydroxide (TEAH)/urea/cellulose solution on viscosity, surface tension, and size of cellulose beads were investigated. Hardwood bleached kraft pulp (HwBKP) was used as a cellulose sauce and the dropping method was utilized to fabricate cellulose beads. Temperature of cellulose solution was varied from 30℃ to 50℃. When the temperature of cellulose solution was increased, the viscosity decreased while the surface tension increased. In addition, increasing the temperature of cellulose solution resulted in the increased size of cellulose beads possibly due to the increased surface tension.

Original Research Article Paper for Screen Printing Applications – A Paper Development Study

Screen printing originated in China during the Song dynasty (960-1279 CE) and is used today in commercial and artistic applications. The presented research project describes the development of a screen-printing product for studio art applications. The improvement of the paper properties from laboratory and small 12-inch laboratory paper machine art paper development, followed by a semi commercial production at a speed of 128 ft/min on a 48-inch semi commercial paper machine for the final art paper, showed an improvement throughout the development process for mechanical and optical paper properties. The finished art paper product exceeded the expectations by the artist using the art paper in the studio. The produced art paper with a basis weight of 63 g/m² and a thickness of 94 µm is produced from a mixture of 70% northern bleached hardwood Kraft pulp and 30% northern bleached softwood Kraft pulp. The ISO brightness and opacity of the art paper bluish gray colour was at 35.6% and 100%, The ISO color value was for the L*, a*, b* Hunter color scale 65.8%, 0.9, and 1-0.7 respectively. As a parameter for attachment of water-based inks, surface roughness was for the top side 1703 ml/min and bottom side (wire side) 1336 ml/min. The Cobb number indicating water penetration of the art paper is 28.9 g/m².Bending stiffness in machine direction and cross machine direction resulted in 22 mN and 12 mN respectively. The tensile index was measured at 52.9 N·m/g for the machine direction and 31.6 N·m/g for de cross-machine direction.

Art Paper for Large Wood Relief Block Printing – A Paper Development Study

Wood relief block printing was developed in China in the seventh century and is used today for many art printing applications. The presented research project describes the development of an art paper product applicable for large wood relief block printing from laboratory scale to large semi commercial production of art paper for printing image sizes of up to 44-inch (1118 mm) by 96-inch (2400 mm) at outdoor steam roller printing events or smaller indoor printing press applications.
 The improvement of the paper properties from laboratory development, small laboratory paper machine and semi commercial paper machine run for the production of the final art paper showed an improvement throughout the process development for the optical and mechanical paper properties and exceeded the set values set by the artist using the art paper.
 The produced art paper with a basis weight of 260 g/m² and a thickness of 171 µm is produced from a mixture of 70% northern bleached hardwood Kraft pulp and 30% northern bleached softwood Kraft pulp.
 The ISO brightness of the art paper off-white (egg-shell) colour was at 63.2% and the ISO color value for L, a, b. at 90.8, 1.1, and 12.6 respectively.
 The art papers surface roughness and porosity as a parameter for ink attachment and penetration is for the top side 2179 ml/min and for the bottom side (wire side) 2326 ml/min, whereas porosity was measured at 1668 ml/min.
 Bending stiffness in machine direction and cross machine direction was measured at 157mN and 70 mN respectively. Burst strength was measured at 2.24 kPA·m²/g.

Application of DSA to improve strength of thermomechanical pulp blended paper

Abstract A more efficient application of a dry strength agent (DSA) was investigated to improve the strength of thermomechanical pulp (TMP) blended paper. Strength improvement by DSA application was more effective for hardwood bleached kraft pulp (Hw-BKP) than TMP. The degree of strength improvement of DSA further increased with the increasing degree of refining of Hw-BKP. The strength of the paper was decreased by the fines fractionation of TMP, but the strength improvement efficiency of DSA for the fines fractionated TMP increased. In order to increase the strength of TMP mixed paper using DSA, it is expected that DSA should be adsorbed only to Hw-BKP with high strength improvement efficiency, not TMP fines. When the DSA was mixed with Hw-BKP before contact with other stocks, it was confirmed that the effect of improving the strength by the DSA is the best. The strength improving effect increased as TMP fines were removed. Therefore, to improve the strength of the paper containing TMP in Hw-BKP by adding a DSA, it is preferable to selective apply the DSA to Hw-BKP while blending only the fibers of TMP by fractionation.

Surface modification of cellulose originated from different plant sources through TEMPO/Laccase/O2 oxidation

An environmentally friendly 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation system using halogen-free reagents has attracted much attention. At present, cellulose nanofibers (CNFs) with a high carboxyl content can be prepared by TEMPO/laccase/O2 (TLO)- oxidation of hardwood bleached kraft pulp (HBKP) under aqueous conditions, while, the related research is still in its infancy. For example, the further applications of TLO-CNFs and the oxidation effect of the TLO system on cellulose from different sources have not been studied. In this work, cellulose from four different sources, that is, HBKP, softwood bleached kraft pulp (SBKP), bleached bagasse sulfate pulp (BBSP) and microcrystalline cellulose (MCC), was oxidized by using a TLO-oxidation system. All cellulose materials were found to be able to be oxidized successfully regardless of the source, which proved the universality of the TLO-oxidation system. Different from traditional TEMPO/NaBr/NaClO (TBN)-oxidation that introduces major carboxyl groups (0.846–1.154 mmol/g) and minor aldehyde groups (0.041–0.097 mmol/g) to cellulose, carboxyl (0.558–0.615 mmol/g) and aldehyde (0.218–0.235 mmol/g) groups can both be sufficiently introduced on the surface of TLO-oxidized cellulose. Based on the aldehyde groups introduced, the wet strength of the TLO-oxidized cellulose handsheet was greatly improved to 400% of the non-oxidized one due to the formation of hemiacetal linkages. In addition, oxidized cellulose can be isolated to homogeneous TLO-CNFs or TLO-cellulose nanocrystals (CNCs), and TLO-CNFs (CNCs) can easily be processed into films and hydrogels with high light transmittance and excellent mechanical properties. Remarkably, compared to the other TLO-CNFs, TLO-CNFs (BBSP) has higher aspect ratio with thinner width (nanofibers as thin as 2 nm can be achieved). Thus, the mechanical properties of TLO-CNFs (BBSP) assembled films and hydrogels were superior to others. These all providing significance and promising prospects for the applications of TLO-oxidation systems, meantime, the distinctive characteristics of TLO-CNFs (BBSP) were explored.

Hydrophobization of Cationic Cellulose Nanofiber Using Rosin Sizing Agent

This study was conducted to explore a new method for imparting hydrophobicity to cellulose nanofiber (CNF) using a rosin sizing agent. Anionic CNF was made from hardwood bleached kraft pulp by micro-grinding; this anionic CNF was then used to prepare cationic CNF through quaternization. The hydrophobization of CNFs was performed by adding the rosin sizing agent to the anionic and cationic CNFs. The zeta-potentials of the CNFs were measured to identify the adsorption rate of rosin sizing agent in the CNFs. CNF films were made from anionic and cationic CNFs containing rosin-sizing agent. The contact angle, FT-IR spectra and burst strength of CNF films were analyzed after heat treatment was conducted to cure the rosin sizing agent.<BR>The zeta-potential of the cationic CNF decreased with the addition of the rosin sizing agent, however there was no significant change in the anionic CNF. After heat treatment of the films, the contact angle of the cationic CNF film was 95°, which was higher than that of anionic CNF film. These results indicated that the anionic rosin sizing agent adsorbed more on cationic CNF than on anionic CNF, and the FT-IR spectra showed the same trend. The burst strength of the CNF film showed the highest value at 3% of rosin sizing agent dosage. Therefore, it was concluded that the rosin sizing agent was effective for the hydrophobization of the cationic CNF and that the dosage should be less than 3% to simultaneously maintain the high contact angle and burst strength of the CNF film.

Mechanical and Hygroscopic Properties of Molded Pulp Products Using Different Wood-Based Cellulose Fibers.

With an increasing interest for molded pulp product (MPP) in the industry, it is important to fully understand how the manufacturing process is different from papermaking. One specific way to differentiate the processes is to compare their resulting products. As the paper industry uses several wood fibers with various pulping processes, it is interesting to compare some of these fibers, to further progress our understanding of the MPP process. In this study, six different wood fibers were used (as received) and analyzed to obtain the sample with the lowest moisture uptake and highest tensile properties. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and fiber analysis module (MorFi) observations were performed, as well as moisture uptake measurements after sorption and tensile tests. We observed significant differences between the fibers tested. Kraft fibers (bleached softwood kraft pulp (BSKP), bleached hardwood kraft pulp (BHKP), and unbleached softwood kraft pulp (USKP)) showed smoother surfaces and less non-cellulosic molecules, such as hemicellulose, lignin, and pectin, in the SEM images. Bleached chemi-thermomechanial pulp (BCTMP) and recycled pulps (R-NPM and R-CBB) both showed non-cellulosic molecules and rougher surfaces. These results were confirmed with the FTIR analysis. With kraft fibers, MPP mechanical properties were lower than non-kraft fibers. Resulting moisture uptake is in between the recycled fibers (lowest moisture uptake) and BCTMP (highest moisture uptake). The removal of non-cellulosic molecules reduces the mechanical properties of the resulting MPP. The incorporation of non-wood molecules, as found in recycled fibers, also reduces the mechanical properties, as well as moisture uptake, when compared with BCTMP.

Effect of Pulp on the Strength of Coloring Paper Used for the Production of Fruit Bags

In the present study, we explored an eco-friendly method for improving the strength of base paper for fruit bags. We determined the fibers characteristics of hardwood bleached kraft pulp (HwBKP), recycled liquid crystal display glass interleaf (LCD), and old newsprint (ONP), which are raw materials used to produce coloring paper. Using various types and mixing ratios of pulp, we produced coloring paper handsheets and determined their strengths. The HwBKP had the highest initial freeness, and as the freeness decreased, the strength of the handsheet increased. The ONP had the lowest initial freeness and paper strength owing to a high recycling rate. The LCD interleaf comprised softwood fibers and was stronger than a handsheet with a Canadian Standard Freeness (CSF) value of 450 mL made from HwBKP. However, when the freeness of HwBKP was 350 mL CSF, the handsheet strength decreased as the mixing ratio of LCD interleaf increased. Therefore, we concluded that it was necessary to decrease the freeness of HwBKP or increase the mixing ratio of LCD interleaf while maintaining the freeness of HwBKP at 400-450 mL CSF to enhance the strength of coloring paper.

Quality Evaluation of Cellulose Nanofiber Manufactured with a Prototype Grinder for the Development of a Taylor-Flow Nanogrinding System

In this study, we aimed to develop a domestic grinder for the production of cellulose nanofibers (CNFs). Therefore, we manufactured a prototype grinder using Taylor-flow nanogrinding technology and evaluated the quality of the CNFs produced using it. To produce the CNFs, we pretreated hardwood bleached kraft pulp (HwBKP) with 0.5% or 1.0% of an enzyme. The enzyme-pretreated CNFs (EN-CNFs) were produced using the prototype grinder, and their particle size, viscosity, and fiber width were measured. As a control, EN-CNFs were also prepared with an imported microgrinder under the same conditions used for the prototype grinder and the same physical properties were investigated.<BR>With regard to the prototype grinder, as the grinding time increased, the particle size and fiber width decreased, and the viscosity increased. The imported grinder showed the same trends. Based on the fiber width of the EN-CNFs, the CNF manufacturing performance of the prototype grinder was judged to be 41.3% of that of the imported grinder. We drew the following conclusions based on our analysis of the fiber width and the difference in design between the two grinders: The effective method for improving the grinding efficiency of a domestic Taylor-flow nanogrinder should be developed by studying the particle size of the diamond coating electrodeposited on the cylinder surface, the gap between the fixed cylinder and the rotating cylinder, and the efficiency of the cooling process.

Understanding the evolution of cellulose fibers during enzyme treatment

Enzyme treatment is a potential strategy for producing cellulose fibrils but its evolution of the mesoscopic and microcosmic structures is not fully understood. In this work, the effect of the properties and microstructures of cellulose bleached hardwood kraft pulp (BHKP) subjected to different enzyme treatment times (0−10 h) on further fibrillation was explored by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The results showed that the enzyme treatment did not change the crystal structure of cellulose but destroyed the intermolecular and intramolecular hydrogen bonds, leading to the increase of the crystal index and size. A thorough investigation on the relation between treatment and evolution of inter-/intra-molecular H-bonds in cellulose including content and cleave sequence of H-bonds was conducted by FTIR peak fitting, second derivative analysis and generalized two-dimensional correlation spectroscopy (2DCOS). Compared to intramolecular H-bonds, the intermolecular H-bonds was first broken with a significant decrease in content. In addition, enzyme treatment could promote the peeling of fibrils, and various properties such as yield, water retention value, aspect ratio, and degree of polymerization, etc. were gradually reduced over time relative to the original material, these discoveries provide a theoretical support to a more effective treatment method for the commercial production of cellulose fibrils.

Effect of Polyelectrolyte-Cationized Cellulose Nanofibril on the Properties of Paper

In this study, the effect of a cationic cellulose nanofibril (CNF), produced by combining surface-modification using cationic polyelectrolyte and micro-grinding, on the strength of paper, was evaluated. Hardwood bleached kraft pulp (HwBKP) was pretreated with poly-DADMAC, and then a method of previous study was conducted, followed by micro-grinding. Afterward, the zeta-potential and fiber width of the untreated and cationic CNFs were measured. The handsheets were produced by adding the untreated and cationic CNFs into the furnish that was prepared with HwBKP and softwood BKP (SwBKP), after which their physical properties were evaluated. The drainage rate and chemical oxygen demand (COD) of the furnish were analyzed based on the addition of CNFs to identify the effect of cationic CNF on the drainage and retention at the wet-end part.<BR>Further, the zeta-potential of the cationic CNF surface-modified with poly-DADMAC exhibited a positive value, but no significant difference was noted in the fiber widths based on the surface-modification. The cationic CNF exhibited higher tensile and burst indexes, and folding endurance because of higher retention at the wet-end part and higher fiber bonds than that in the untreated CNF. However, the cationic CNF did not show the difference in the ISO brightness and opacity of the paper, and the drainage rate of the furnish from untreated CNF. Thus, it was concluded that the cationic CNF, produced via surface-modification using poly-DADMAC and micro-grinding, was more effective in improving the strength of the paper regarding the similar optical properties of the paper, as well as the drainage rate of the furnish, compared with untreated CNF.

Combining phosphotungstic acid pretreatment with mild alkaline extraction for selective separation of hemicelluloses from hardwood kraft pulp

In this study, a modified process, namely PTA-4%CCE, consisting of an initial phosphotungstic acid (PTA) catalytic hydrolysis, followed by a low-alkali cold caustic extraction (4%CCE) was investigated for upgrading a bleached hardwood kraft pulp to dissolving pulp via selectively removing hemicelluloses. The results showed that the PTA hydrolysis resulted in degraded hemicelluloses with low molecular weight and an increased fiber accessibility. These favorable changes of fiber morphologies facilitate the alkali penetration inward and hemicelluloses diffusion/removal outward even under a very low alkali concentration (4% NaOH) in the subsequent CCE stage (4%CCE), thus enabling a high hemicellulose removal selectivity (85.2%) while decreasing alkali usage. PTA also showed excellent recyclability/reusability with more than 86% recovery. The cellulose purity and reactivity of resultant pulp were 94.92% and 49.5%, respectively. This study reveals that the modified process provides a sustainable and effective strategy for hemicelluloses separation from cellulose fibers.

Converting bleached hardwood kraft pulp to dissolving pulp by using organic electrolyte solutions

In this laboratory study, a hardwood bleached kraft pulp (HBKP) was converted to dissolving pulp by removing hemicellulose using organic electrolyte solutions (OES), consisting of ionic liquid (1-ethyl-3-methylimidazolium acetate (EminAc)) and a polar organic solvent γ-valerolactone (GVL). The molar ratio of GVL/EmimAc, and temperature have significant effect on the swelling of HBKP fibers, thus the hemicellulose dissolution/removal process. Under the optimal conditions of GVL/EmimAc molar ratio of 4 and 60 °C, hemicellulose was effectively removed, leading to the formation of a dissolving pulp with yield of 76%, cellulose content of 91%, Fock reactivity of 56.8% and viscosity of 723 mL/g. Furthermore, the potential of using EmimAc/GVL/water ternary system to selectively remove hemicelluloses from the same HBKP was studied. The GVL/EmimAc/water ratio of 2:1:1 at 60 °C showed promising results, with yield of 76.7%, and cellulose content of 94.8%.

감나무 부산물로부터 제조된 셀룰로오스 나노피브릴의 물성 평가

In this study, we evaluated the applicability of fruit by-products as raw materials for the production of cellulose nanofibril (CNF). The persimmon byproducts generated by pruning persimmon trees were collected and used for the manufacture of bleached kraft pulp and CNFs. The persimmon byproduct bleached kraft pulp (PB-BKP) was made at the optimum pulping and bleaching conditions reported in the previous study and the CNFs were made from PB-BKP and commercial hardwood bleached kraft pulp (Hw-BKP) by refining and micro-grinding processes. After micro-grinding, the particle size, viscosity, zeta potential, and fiber width were evaluated according to the pass number of fibrillation. The appearance of the CNF slurries showed no significant difference between PB-BKP and Hw-BKP. It was found that nanoization of PB-BKP and Hw-BKP proceeded sufficiently when the pass number was five or more. In addition, as the pass number increased, the low shear viscosity of CNF increased, the particle size decreased, and no significant change was observed in the zeta potential. Looking at each pulp, CNF made of PB-KBP had higher fiber width and particle size than Hw-BKP in the initial pass number, but the difference decreased when the pass number was nine. Therefore, CNF made with PB-BKP and CNF made with Hw-BKP showed similar characteristics after the sufficient pass number of micro-grinding. Based on the results, we concluded that persimmon tree by-products can be used as raw materials for the production of CNF.

Using ionic liquid (EmimAc)-water mixture in selective removal of hemicelluloses from a paper-grade bleached hardwood kraft pulp

In this paper hemicellulose was separated by using 1-ethyl-3-methylimidazolium acetate (EmimAc, an ionic liquid) -water mixtures from a paper grade market bleached hardwood kraft pulp to produce dissolving pulp. Pure EmimAc dissolves pulp fibers completely in 30 min at ambient temperatures. By adding water (as an antisolvent to EmimAc system) the cellulose dissolution decreases and by optimizing the conditions, hemicellulose is largely removed while cellulose remains as the solid residue (dissolving pulp). At optimal conditions: molar ratio of water to EmimAc of 2, 60 °C, an alpha-cellulose content of 92.2%, with a high yield (78 wt%) was obtained. The viscosity of the solvent mixture decreases by increasing water to EmimAc molar ratio, which improves the mobility of ions, thus, facilitating their penetration into pores and lumens of the fibers during the dissolution process. Cellulose purity increases and purified cellulose yield decreases with the increases in temperature and water content (up to 2 wt%) in the mixture. This study implies that the optimal EmimAc/water mixture is an effective system to separate hemicellulose from hemicellulose/cellulose matrix.

Forecasting the Import Price of Hardwood Bleached Kraft Pulp Using a Time-Series Model

Managing the import price risk of hardwood bleached kraft pulp (Hw-BKP) is a major concern of the Korea paper industry due to high price volatility. The primary objective of this study is to develop forecasting models for the import price of Hw-BKP as a tool to reduce price risk. Six different types of extended autoregressive models with various rolling window size were evaluated based on multiple accuracy measures. Results show that forecasts from the models with exogenous and monthly dummy variables are more accurate than the others. An autoregressive model with exogenous and monthly dummy variables model (ARMX) using a window size of 36 months outperforms the other models. When applying the model, it is possible to reduce the mean absolute error (MAE) by 24.6% and the root mean square error (RMSE) by 35.3% compared to a naive forecast model.

The surface softness and mechanical properties of wood pulp–lyocell wet-laid nonwoven fabric

This study explores the tensile properties of wet-laid nonwoven fabric made from softwood bleached kraft pulp (SwBKP), hardwood bleached kraft pulp (HwBKP), dissolving pulp (DP), and Lyocell. Five different ratios of wood pulp and Lyocell (0/100, 10/90, 20/80, 30/70, 40/60, and 50/50) were manufactured using papermaking technology, which is similar to wet-laid technology. The results indicate that the properties of strength and surface softness of a nonwoven fabric are enhanced by the contribution of the entanglements of wood pulp–Lyocell. Of the three pulps, SwBKP is superior to both HwBKP and DP on account of its higher properties of density and tensile strength, which are increased by refining treatments. In terms of the surface softness component results, HwBKP has a lower MMD value than the other samples. The SwBKP–Lyocell mixing ratios with the minimum ratio of 30/70 were found to offer sufficient tensile strength with improved softness.

Structural analysis of CaCO3 nanoparticle/pulp fiber composites by tube flow fractionation

Two slurries that consisted of precipitated calcium carbonate (CaCO3) nanoparticles and unbeaten hardwood bleached kraft pulp (HBKP) were prepared via ultrafine bubble and mixing methods. In the ultrafine bubble method, a CO2 gas flow was bubbled into a HBKP slurry that contained Ca(OH)2 to prepare a precipitated CaCO3/HBKP composite slurry. The HBKP/water and precipitated CaCO3/water slurries were prepared separately and mixed to prepare a precipitated CaCO3/HBKP mixture slurry. Each of the two CaCO3/HBKP slurries was separated into five fractions using a tube flow fractionation (TFF) system. The first and second fractions consisted of long HBKP fibers and fiber aggregates. The third fraction had the highest mass ratio of the components in the five fractions, and it had approximately 1-mm-long HBKP fibers. The fourth fraction contained primarily HBKP short fibers and CaCO3 aggregates. Thus, the CaCO3/HBKP components in the slurry were separated adequately by TFF, depending on their hydrodynamic sizes. The average width of each fraction in the CaCO3/HBKP composite slurry was always larger than that of the corresponding fraction from the CaCO3/HBKP mixture slurry, which indicated that precipitated CaCO3 nanoparticles and their aggregates attached stably to long and short pulp fiber surfaces in the composite slurry.