Chemimechanical Pulp Research Articles

Effect of Ozone Treatment on the Properties of Oil Palm Empty Fruit Bunch Sulfonated Chemi-Mechanical Pulp

Oil palm empty fruit bunch (EFB) as an abundant waste material can be utilized for pulp production to alleviate the shortage of raw materials in the paper industry. Sulfonated chemi-mechanical pulp (SCMP) has great potential in paper making industry. However, its poor performance due to the high surface lignin content limits its application. In this study, we used EFB as raw material to produce SCMP and systematically studied the effect of ozone treatment on pulp properties. Results show that the surface structure and morphology of fibers exhibited distinct differences under different ozone dosage treatments. Compared to the control, the content of surface lignin of pulps was reduced by 2.56%, 4.64%, 13.24% and 25.24% when ozone consumption was 1, 3, 5 and 7 wt%, respectively. Meanwhile, the treated pulp had a lower drainability at the same refining energy level. Moreover, the physical and optical properties of handsheets were improved significantly after ozone treatment. Ozone treatment is a very efficient way to improve the performance of SCMP. Additionally, this method avoids complicated processes and chemical consumption. Therefore, as an effective, environmentally friendly and low-cost treatment method, ozone treatment can improve the performance of EFB SCMP and thus provide a high-quality pulp resource.

Effects of montmorillonite nanoclay on the properties of chemimechanical pulping paper

The effects of nanoclay were studied relative to the physical, mechanical, optical, and morphological properties of chemimechanical pulping papers. Nanoclay was incorporated at 0%, 2%, 4%, 6%, 8%, or 10%. To increase the retention, 1% cationic starch was used in all test papers. Handsheets (60 g/m2 in weight) were tested to determine their physical, mechanical, optical, and morphological properties. Up to 2% nanoclay increased the tensile strength; at values greater than 2%, the tensile strength decreased. The addition of up to 4% nanoclay increased roughness; between 4% and 10% nanoclay, roughness decreased. With 10% nanoclay, the tear strength, burst strength, and brightness decreased, but the air resistance, opacity, and yellowness increased. Scanning electron microscopy showed that the nanoclay filled the pore spaces between fibers, thus increasing air resistance. X-ray diffraction patterns indicated an intercalated structure.

Aspects on bond strength in sheet structures from TMP and CTMP – a review

AbstractHigh yield pulps (HYP), manufactured in mechanical and chemimechanical pulping processes, are mainly used in graphic papers and paper grades where a high bulk is preferable, like in paperboards. Moreover, packaging papers with very high demands on both dry and wet strength could be manufactured from HYP in a near future. Preferred bonds between fibre components (long fibres, shortened fibres and fines) in the various paper grades are quite different. In the review, plausible effects of mechanical interlocking, intermolecular interactions (“physical bonding”), hydrogen bonds, intermixing of polymers, additives and possible specific interactions in the formation of strong bonds in sheet structures from HYP are discussed. A required condition for high bond strength in sheets from HYP furnishes is that fibre components are forced into sufficiently close contact. This is to a great extent impeded if the fibre walls are too stiff. Consequently, the current review focuses on both how fibre fractions should preferably be developed for different end uses and how suitable bonds might be achieved in different paper grades. The ideal type of bonds is certainly different depending on the demands on the final paper quality.

Replacement of imported long fiber kraft pulp with lignocellulosic nanofibers and cationic materials in the production of durable paper

Usage of cellulosic nanofibers, starch-nanocellulose, and polyacrylamide-nanocellulose hybrid systems were investigated for the replacement of imported long bleached kraft fibers in the production of durable papers. In this study, imported softwood kraft pulp was added to cotton pulp at four levels. Nanofibrillated cellulose (NFC) prepared from chemimechanical pulp was added to cotton pulp at a 5% level with optional 1% cationic starch or 0.1% cationic polyacrylamide. Comparative tests were done without NFC at three levels of either cationic starch or cationic polyacrylamide. For each condition, 80 gm-2 handsheets were made, and the physical, mechanical, and optical properties of the paper were compared. The results showed that increases of NFC yielded higher surface smoothness, tensile strength, resistance to bursting, tearing energy, folding endurance, yellowness, and opacity. It also reduced brightness and porosity whether added singly or in combination with cationic starch or polyacrylamide. Increasing cationic starch also increased surface smoothness, tensile strength, resistance to bursting, and folding endurance, but paper opacity was reduced. The field emission-scanning electron microscopy results showed that increased NFC reduced porosity, the paper surface became smoother, and the pores were relatively filled. Finally, the combined treatment of 5% NFC and 1% cationic starch is introduced as a suitable combination.

Ceibapentandra (L.) Gaertn (Kapok) Seed Fibre as a Recycled Paper Reinforcement Pulp

The kapok (Ceibapentandra (L.) Gaertn) seed fibre is unicellular with length up to 35 mm, however, it is covered by a hydrophobic waxy layer that limits its application in paper production. In this study, the effect of various pulping methods namely mechanical, chemi-mechanical, semichemical and chemical pulping on kapok fibre properties was investigated. Each kapok pulp was then blended with the secondary fibre recovered from kraftliner board for handsheet making to examine their reinforcing ability on strength properties. The results showed that kapok mechanical pulps (with and without dewaxing (5% (v/v) diluted detergent) and chemimechanical pulp were unable to improve the strength properties of the handsheet. Kapok pulps chemically treated with 18–25% of sodium hydroxide gave a better effect on handsheet strength properties whilst fibre treated with 20% sodium hydroxide showing the highest increment. Although the reinforcing effect of the 4% native cooked starch was slightly higher than that of the 10% kapok pulp blended in recycled paper, the recycling potential of the latter was better as all strength properties retained unchanged after recycling. The findings indicated that kapok chemical pulp is a promising reinforcing fibre source with superior recycling potential.

Low-cost and high-wet-strength paper-based lignocellulosic adsorbents for the removal of heavy metal ions

Paper-based lignocellulosic adsorbents with high wet strength, high adsorption capacity and good separation and recycling performance were prepared from polar chemimechanical pulp by simple papermaking and one-step dip coating. Green crosslinking agent of citric acid, which can react with the hydroxyl groups of cellulose under the catalysis of sodium hypophosphite, was used to increase the wet strength as well as the carboxyl content of the paper-based adsorbents. Both the wet strength and carboxyl content increase upon increasing the beating degree and the dosage of citric acid. The wet strengths reach 40∼50 % of their dry strengths and the carboxyl contents are tuned in the range of 0.07∼ 0.66 mmol/g. Pseudo-second-order equation was found to fit the kinetics data best, indicating the adsorption is chemisorption process. The good agreement of equilibrium data with Langmuir model confirm the monolayer coverage of Cu(II) and Pb(II) onto adsorbents. The maximum adsorption capacities of Cu(II) and Pb(II) are high up to 61.96 and 138.11 mg/g, respectively. Good regeneration stability and more than 90% of its initial adsorption capacity are achieved even after four adsorption-regeneration cycles, and the adsorbents are basically unaffected during the desorption process. In addition, the paper-based adsorbents with micron pores are able to effectively separate particles with the size larger than 50 μm. Combined with the filtration device, the paper-based adsorbents are easy to realize the continuous adsorption process and can be simply recycled from water without separation difficulty. The synthetic strategy of multifunctional paper-based adsorbents from polar chemimechanical pulp provides new ideas and methods for the full and high-value utilization of lignocellulose.

Recycle cooking wood chips with the residue liquid removed out of lignin by calcification for increasing pulp yield and reducing waste water discharge

A large amount of low-concentration wastewater is produced during the production of chemical mechanical pulp. Due to low concentration, a large amount of energy is consumed by evaporation to prepare its concentrated liquor for combustion; resulting high cost in treating the waste liquor by the evaporation-combustion method. In order to solve this problem, a new method to treat chemical mechanical pulping waste liquor by directly calcification reaction is developed to remove out of lignin and generate sodium hydroxide in the treated residue liquid for recycle cooking wood chips; and thereby to improve the pulp yield and reduce waste water discharge. The pulp yields by recycle cooking are in the range of 86.7%–90.59%, being 9.6%–13.3% higher than that of the initiate cooking without the treated residue liquid. By the method, it reduces 90.6% of the cooking and milling waste liquor in the modeling pulp mill applying the recycle cooking wood chips technology.

Effect of nanofiber addition on the physical–mechanical properties of chemimechanical pulp handsheets for packaging

The effect of nanofiber addition on the physical–mechanical properties of industrial chemimechanical pulp handsheets was evaluated. The nanofibers (3 wt%) were added to industrial pulps taken from two positions of the approach flow, trying to reproduce the real paper machine process. Significant correlations between the characteristics of the cellulose nanofibers, the drainability of pulp suspensions, and the physical–mechanical properties of handsheets were found. The increase in the degree of fibrillation decreased significantly the drainability of the pulp suspensions. Nanofibrillation yield, transmittance, viscosity at 0.5% consistency, and carboxylic content positively correlated with °SR, whereas turbidity, and ξ-potential correlated negatively. Nanofiber incorporation increased Tensile Index (up to 21%), Burst Index (23–37%), E modulus (up to 17%), concora medium test (up to 27%), ring crush test (up to 28%), and short-span compression test values up to 23% in the handsheets where nanofibers from bleached kraft pulp were added. A positive correlation was found between the Tensile Index and nanofibrillation yield, and between E modulus and viscosity at 0.5% consistency for all pulps and a high linear relationship between both variables was found for nanofibers from pine pulps. Finally, the values of air permeability decreased up to 80% respect to the control.

Optimization of sulfonated chemi-mechanical pulping of palm oil empty fruit bunch using response surface methodology

In order to optimize the sulfonated chemi-mechanical pulping of palm oil empty fruit bunch, the response surface methodology was employed. It was intended to determine the optimum level of sodium sulfite dosage, sodium hydroxide dosage, maximum cooking temperature, and cooking time at the sulfonation stage, and their influences on paper sheets properties were analyzed. An optimum compromise was obtained, and the sodium sulfite dosage, sodium hydroxide dosage, maximum temperature, and cooking time were 18%, 4%, 155 °C, and 100 min, respectively. The density, bursting strength index, tensile strength index, and tearing strength index were 0.5622 g/cm3, 2.60 kPa·m2/g, 45.01 N·m/g, and 7.53 mN·m2/g, respectively.

ZnAl2O4/BiPO4 composites as a heterogeneous catalyst for photo-Fenton treatment of textile and pulping wastewater

ZnAl2O4/BiPO4 heterostructures were successfully obtained via co-precipitation and hydrothermal method. The photocatalytic efficiency of ZnAl2O4/BiPO4 composites were improved and seriously influenced by the loading content of ZnAl2O4 under UV light. Photocatalytic tests showed that the kinetic constant of 1 wt% ZnAl2O4/BiPO4 composites for methylene blue degradation under UV irradiation were 0.959 h−1, which is 2.47 and 18.10 times as large as that of pure ZnAl2O4 and BiPO4, respectively. The enhanced photocatalytic performance of ZnAl2O4/BiPO4 heterojunctions was ascribed to effective separation of photo-generated electron–hole pairs. The photogenerated holes (h+) and OH were the primary reactive species in the MB degradation over ZnAl2O4/BiPO4 composites. Photo-Fenton-like reaction was initiated with H2O2 addition, which significantly improved the photocatalytic activity of ZnAl2O4/BiPO4. The CODCr and color removals of textile wastewater over ZnAl2O4/BiPO4/H2O2 under UV irradiation were 76.74% and 83.22%, and the CODCr and color removals of eucalyptus chemimechanical pulp wastewater (ECMPW) over ZnAl2O4/BiPO4/H2O2 under UV irradiation were 73.98% and 84.54%, respectively. This work provides a new insight for constructing efficient flexible heterogeneous photocatalysts for wastewater purification.

Bleachability improvement of eucalypt mechanical pulps using hydrogen peroxide in ethanol-water media

Alkaline darkening has a negative effect on chemimechanical pulps produced from various eucalypt chips. For instance, the pulp’s brightness has been found to drop rapidly when alkali addition exceeds its optimum amount. Therefore, to compare the effects of different media on brightness gain, eucalypt mechanical pulps were bleached using a typical peroxide bleaching sequence in a water medium and in an ethanol-water (E/W) medium. Various pulp brightness levels and changes of residue chemicals in the spent bleaching liquors were investigated. Compared to water medium, the net brightness gain notably increased when using the E/W medium at the same chemical dosages. The rate of pulp brightness loss caused by increasing alkali dosage dropped in the E/W medium. Analyses based on ultraviolet-visible diffuse reflectance spectra of bleached pulps, as well as gel permeation chromatography and pyrolysis-gas chromatography-mass spectrometry spectra of the residues in the spent bleaching liquors, indicated that the contributions to brightness improvement from ethanol-water media could be explained by the selective dissolution and removal of phenolic- or guaiacyl-structured lignin fragments that result in the formation of chromophoric groups under alkaline conditions.

Mixed-Framework-Based Energy Optimization of Chemi-Mechanical Pulping

The papermaking industry supplies the carrier for literature and packaging via chemi-mechanical pulping, which is the most commonly used approach for converting wood chips into cellulose fibers. In 2016, Chinese papermaking enterprises consumed 41.05 million tons of standard coal. Thus, it is important to reduce the electrical energy consumed in mechanical pulp production by optimizing the operating conditions of primary stage refiners. This article reports a two-stage optimization algorithm to achieve this objective. First, mixed data sampling regression combined with a new weighting scheme derived from mixed flow conditions is used to encode the characteristics of high consistency refiner (HCR) in the manufacturing system. Then, the genetic algorithm with self-adaptive population searches for the optimal operating parameters that can minimize the power cost of the papermaking process. The proposed mixed framework and its separate components are validated through numerical functions and practical datasets, all of which have competitive performances compared to other algorithms. After being applied to a papermaking plant for two months, the intelligent optimization algorithm is found to have significant economic achievements in reducing the HCR energy consumption by 1.67 kWh/adt on an average scale.

Staged alkali and hydrogen peroxide treatment of poplar chemi-mechanical pulp

In order to improve the physical properties and brightness of poplar chemi-mechanical pulp, a new staged alkali and hydrogen peroxide treatment method was proposed and applied. Wood chips were impregnated and swelled with an alkali solution and then treated with a hydrogen peroxide bleaching liquor. A thorough evaluation and comparison of the physical properties and brightness of the pulps that underwent different treatment methods was conducted. The results showed that when the pulp was treated with an alkali and hydrogen peroxide treatment method with an alkali dosage of 6% and a hydrogen peroxide dosage of 6%, the tear index was 3.64 mN‧m2/g, the tensile strength was 3.61 kN/m, and the pulp brightness was 67.1% (ISO). The obtained physical properties and brightness of the alkali and hydrogen peroxide method treated pulp were greater than the traditional alkaline hydrogen peroxide method values, as well as the values of any other single treatment methods.

Effect of enzymatic hydrolysis lignin on the mechanical strength and hydrophobic properties of molded fiber materials

Abstract In this study, poplar chemi-mechanical pulp was used as a raw material to investigate the effect of enzymatic hydrolysis lignin (EHL) content on the tensile strength and hydrophobicity of molded fiber materials (MFMs). The tensile strength and hydrophobic properties of the fabricated MFMs with different EHL contents were evaluated, and changes in their microstructure, chemical structure, and thermal stability were characterized via scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric (TG) analysis, respectively. Results show that under the experimental conditions used herein, the addition of EHL could increase the tensile strength and surface water contact angle of MFMs up to 20.3 MPa and 95.0°, respectively. The SEM observations indicate that the addition of EHL expanded the contact area between the EHL and fibers, thereby reducing the holes between fibers. The FTIR and TG analyses indicated that hot-pressing degraded EHL to form small molecular substances and improved the reaction with aldehydes produced via carbohydrate degradation, improving both the inter-fiber bonding strength and hydrophobicity of the MFM surface.

Color evolution of poplar wood chips and its response to lignin and extractives changes in autohydrolysis pretreatment

Combining chemi-mechanical pulping with autohydrolysis pretreatment is an efficient and value-added utilization approach for lignocellulosic biomass in paper industry. To further promote the utilization of autohydrolyzed biomass in chemi-mechanical pulping, the color evolution of poplar wood chips in autohydrolysis pretreatment and its chromogenic mechanism were investigated by using CIELab color system, FT-IR, NMR and GPC. The results showed that the total color difference ΔE* increased obviously, which were remarkable as the combined hydrolysis factor (CHF) increased. The lignin content led to a more significant influence on the color of poplar wood chips than the extractives. The autohydrolysis pretreatment with a higher CHF accelerated the degradation and subsequent condensation of lignin, resulting in the formation of chromophoric groups, such as Hibbert ketone, quinones and quinone methides. It is of great significance for biomass refinery and paper industry to reveal the color evolution of poplar wood chips caused by autohydrolysis pretreatment from the point of view of chemical components' structure.

Strength Improvement of Wheat Straw Chemi-mechanical Pulp by the NaOH-urea Pretreatment

Strength Improvement of Wheat Straw Chemi-mechanical Pulp by the NaOH-urea Pretreatment

ZnAl2O4/Bi2MoO6 heterostructures with enhanced photocatalytic activity for the treatment of organic pollutants and eucalyptus chemimechanical pulp wastewater

A novel ZnAl2O4/Bi2MoO6 heterostructures have been successfully prepared by co-precipitation and hydrothermal method. Excellent photocatalytic performance and stability of the composites was exhibited in the degradation of methylene blue dye solution under UV light irradiation, and seriously affected by the ZnAl2O4 content in the heterostructures. Moreover, the highest MB removal was 86.36% at 3 h under UV irradiation over 0.5 wt% ZnAl2O4/Bi2MoO6, increased by 35.20% of pure Bi2MoO6 and 72.03% of ZnAl2O4, respectively. The enhanced photocatalytic efficiency of composites was contributed to the rapidly separation of photogenerated electrons and holes. Additionally, the ZnAl2O4/Bi2MoO6 were also used to treat the biochemical wastewater of industrial eucalyptus chemimechanical pulp, which demonstrates a high COD removal of 50.88%. This study provides that Bi2MoO6 based heterogeneous photocatalysts show a promising perspective in the industrial effluents treatment.

Study on Refining Performances in Chemi-mechanical Pulping of Mixed Poplar and Eucalypt Woodchips

Study on Refining Performances in Chemi-mechanical Pulping of Mixed Poplar and Eucalypt Woodchips

Effect of nano-cellulose on the improvement of the properties of paper newspaper produced from chemi-mechanical pulping

The effect of nanofibrillated cellulose (NFC) was investigated relative to the strength of chemi-mechanical pulp (CMP) and paper. The NFC was added at five levels: 0%, 2%, 4%, 6%, and 8%. Handsheets with a basis weight of 60 g/m2 were prepared, and the physical properties (air resistance and surface roughness), the mechanical properties (tensile strength, burst strength, and tear strength), and the optical properties (brightness, opacity, and yellowness) were measured according to TAPPI standards. By increasing the NFC content, the tensile strength, burst strength, air resistance, brightness, and whiteness increased by 10.9%, 12.5%, 23.6%, 0.6%, 3.5%, and 6.8%, respectively, compared to the control (0% NFC) samples. By increasing the NFC content, the tear strength, roughness, and opacity decreased by 10.4%, 11.1%, and 0.6% compared to the control samples.

A novel core–shell structured biosorbent derived from chemi-mechanical pulp for heavy metal ion removal

Carboxymethylated cellulose fiber (CMF), a cellulose-based biosorbent, was prepared from chemi-mechanical pulp. The CMF biosorbent showed a high stability/recovery and an excellent adsorption capacity during the metal ion removal due to its unique core–shell structure: (1) the CMF maintained a good fiber formwork even at a high carboxyl content level (175.40 mmol/100 g) due to the protection of carboxymethyl-free lignin shell on the fiber surface, thus facilitating the follow up separation/recovery of CMF; (2) the high carboxyl content in the core of CMF cellulose enabled its strong adsorption capacity towards metal ions. The results showed that the adsorption behavior fitted well to the pseudo-second-order kinetic and the CMF had high selective adsorption towards Pb(II). The CMF also exhibited an excellent recycling performance. Therefore, the as-prepared CMF with high adsorption capacity, good solid–liquid separation and high regeneration performance indicates that the novel core–shell CMF biosorbent can provide a method to remove metal ion in practical wastewater treatment.