Kraft Pulping Process Research Articles

Irradiation based clean and energy efficient thermochemical conversion of biowaste into paper

The advancement in plastic and plastic based products in last two decades has imposed a serious threat to the environment. This has led to an increase in the demand for sustainable and biobased products. Paper and paper products are good alternatives to their plastic counterparts. A key element of paper industry is the raw material (wood, bamboo and nonwood agricultural residues such as bagasse, straws etc.) from which pulp is produced. The pulp is then utilized for production of paper. There are many pulping processes to prepare pulp of various qualities. For fine grade pulp, chemical pulping is used. The chemical pulp is produced by soda, kraft and sulphite pulping processes. However, for newsprint grade pulp, stone ground wood (SW), thermomechanical (TMP), chemi-thermomechanical (CTMP), chemi-mechanical (CMP) or refiner mechanical (RMP) corresponding pulping processes are employed. The method of pulp preparation (pulping process) consumes large amount of energy and chemicals. A new pulping process with electron irradiation using biowaste (bagasse) as a raw material is discussed in this work. Bagasse pulping process is found to reduce about 50% of energy consumption during pulping process. The process is referred to as ‘ECTMP’ (Energy Efficient Chemi-Thermo Mechanical Pulping). The paper produced from aforesaid method also reflected no loss of strength properties with respect of TMP reference pulps. Henceforth, preliminary calculation based on experimental results shows that the proposed bagasse ECTMP process explored the scope of energy savings of the order of 50%.

In vitro cytotoxicity studies of industrial Eucalyptus kraft lignins on mouse hepatoma, melanoma and Chinese hamster ovary cells

Kraft lignin is a polyphenolic compound generated as a by-product from the kraft pulping process in large quantities annually worldwide. In addition to its commercial availability, its structural features make it worth to be considered in the pharmaceutical area. The present study was carried out to evaluate in vitro antioxidant and cytotoxic properties of kraft lignin on mouse hepatoma MH-22A, melanoma B16 (tumor cells) and Chinese hamster ovary (CHO, non-cancerous) cells. Moreover, several analytical techniques were used in order to elucidate the chemical structure of isolated industrial lignins (FT-IR, GPC, Py-GC–MS, 2D HSQC NMR). Results revealed high phenolic content in their composition, high-condensed structure and high phenolic hydroxyls group content. DPPH and ABTS⁎+ radical scavenging assays demonstrated their strong antioxidant activity, which was higher than found for commercial antioxidant (BHT). Kraft lignins act cytotoxically inducing apoptosis- and necrosis-like processes on both on tumor and normal cells. However, the results evidenced that MH-22A cells showed greater sensitive behavior than B16 and non-cancerous CHO cells, which were more tolerant of kraft lignin.

Population balance modeling of cationic polyacrylamide (CPAM) induced flocculation process for lignin recovery from the pre-hydrolysis liquor of kraft pulping process

In order to predict and control the CPAM induced flocculation process for lignin recovery and subsequent dissolved hemicelluloses utilization from pre-hydrolysis liquor (PHL), quantitative population balance model which can describe aggregation, breakage and restructure phenomenon in the flocculation process was developed to describe the process. The simulation results showed, in general, high charge CPAM resulted in lower collision efficiency, lower restructure rate and stronger flocs than the lower charged CPAM. The increase of CPAM dosage had positive effect on collision efficiency and restructure rate and negative effect on energy dissipation rate. With the increase of temperature, low charge density CPAM flocculation system experienced more significant change regarding energy dissipation rate and restructure rate. The collision efficiency was not significantly affected by the temperature change for both CPAMs. Shear rate had negative effect on collision efficiency, positive effect on energy dissipation rate and restructure rate. The addition of salt slightly increased the collision efficiency, decreased the energy dissipation rate for both CPAMs system. More negative effect is observed for high charge density flocculation system.

Synthesis of lignin based composites of TiO2 for potential application as radical scavengers in sunscreen formulation

Titanium dioxide (TiO2) is added in sunscreens due to its ability to absorb ultraviolet (UV) light. However, upon irradiation of UV light, reactive oxygen species particularly hydroxyl radical which can damage human skin will be generated. In this study, lignin/TiO2 composites were employed to quench the hydroxyl radicals generated by the TiO2. The lignin was extracted from oil palm empty fruit bunch (OPEFB) via kraft and soda pulping processes. The kraft lignin composite was labelled as KL/TiO2 whereas the soda lignin composite was labelled as SL/TiO2. The lignins and the composites were characterized by FTIR, UV spectroscopy, 13C NMR, SEM, EDX, and XRD. The relative hydroxyl radical production of composites and TiO2 were compared through photo-oxidation of coumarin to 7-hydroxycoumarin as a test medium. The effect of types and amounts of lignin used were studied. The KL/TiO2 composite showed the least radical production due to higher phenolic hydroxyl content of kraft lignin. The activity of the hydroxyl radicals will be quenched when it abstract hydrogen atoms from the phenolic hydroxyl groups.

Introduction of the Latest Solution for Productivity Improvement in Kraft Pulp Process

Introduction of the Latest Solution for Productivity Improvement in Kraft Pulp Process

Preparation and Evaluation of Papermaking Pigments Using Kraft Pulping Process By-products

Preparation and Evaluation of Papermaking Pigments Using Kraft Pulping Process By-products

Preparation and Characterization of Green Epoxy Resin Composites and Its Use in Corrosion Resistance

In this work, appropriate alternative for diglycidyl ether bisphenol A (DGEBA) was found to avoid the destructive effects of bisphenol A. Lignin, an aromatic compound from palm tree leaves, was used as a renewable material to synthesize a bio-based epoxy resin. Lignin extracted using Kraft pulping process. Kraft Lignin was epoxidized with epichlorohydrin in alkaline medium. Nano-titanium dioxide was used as filler with ratio of 10% to prepare the green epoxy composite. The structure of the Kraft lignin and lignin-based epoxy resin was proven via Infrared spectra (FT-IR) were recorded using solid KBr disk by testing Shimadzu (FT-IR-8300) spectrophotometer. The thermal properties of the curing process of lignin-based epoxy resin and composite were investigate using Differential scanning calorimetry (DSC) analysis. Potentiodynamic measurements data revealed that the anti-corrosion performance of the lignin based epoxy resin. The study demonstrates successful of epoxidation of Kraft lignin. In addition, lignin based eopxy resin showed effective inhibitor for carbon steel in 3.5 wt. % NaCl electrolyte solutions

A process for purifying xylosugars of pre-hydrolysis liquor from kraft-based dissolving pulp production process

BackgroundIn the kraft-based dissolving pulp production process, pre-hydrolysis liquor (PHL) is produced, which contains hemicelluloses, lignin, furfural and acetic acid. PHL is currently burned in the recovery boiler of the kraft pulping process, but it can be utilized for the generation of high-valued products, such as xylitol and xylanase, via fermentation processes. However, some PHL constituents, e.g., furfural and lignin, are contaminants for fermentation processes and they must be eliminated for production of value-added products.ResultsIn this work, a process is introduced for removing contaminants of PHL. Ca(OH)2 treatment is the first step of this process, which removed 41.2% of lignin and negligible amount of sugars. In this step, a notable increase in the concentration of acetic acid was achieved (ranging from 6.2 to 11.7 g/L). In the second step, the implementation of adsorption using activated carbon (AC) at 1 wt% dosage led to additional 32% lignin and 5.9% xylosugar removals. In addition, laccase assisted activated carbon treatment led to further removal of lignin via accelerating lignin polymerization and adsorption on AC (i.e., removal from PHL). Overall, 90.7% of lignin, 100% of furfural, 5.7% of xylose, and 12% of xylan were removed from PHL, while the concentration of acetic acid became twofolds in the PHL.ConclusionsThis study reports an attractive process for purifying sugars and acetic acid of PHL. This process may be implemented for producing sugar-based value-added products from PHL. It also discusses the mechanism of Ca(OH)2 treatment, AC adsorption and laccase assisted activated carbon treatment for lignin removal.

Process Parameters Optimization of Casuarina equisetifolia for Enhanced Production of Bleachable Grade Kraft Pulp through RSM

Casuarina equisetifolia (beach sheoak), a fast-growing deciduous tropical hardwood tree, was utilized to assess its suitability for pulp and paper production. Response surface methodology (RSM) based on central composite design (CCD) was used to optimize the kraft pulping process by varying the alkali doses, reaction temperature, and time. Using the best optimum pulping conditions with alkali charge 17.9%, temperature 170.2 °C, and pulping time 82.1 min, a high screened pulp yield of 52.4% with low kappa number of 18.1 and pulp viscosity of 974.5 cm3/g could be achieved. The laboratory handsheets prepared with kraft pulp under optimum conditions showed good mechanical strength properties at an optimum beating level of 45 °SR.

Isolation and Characterization of Cellulose Nanocrystals from Rejected Fibers Originated in the Kraft Pulping Process.

In the final process of the bleached kraft pulp there are some cellulose fibers that are separated from the main fibers stream; these fibers are rejected and considered as a low quality fibers, these fibers are known as rejected fiber (RF). In the present work the potential use of these fibers for Cellulose Nanocrystals (CNCs) synthesis was studied. The physical and chemical properties of synthesized CNCs were characterized through different techniques such as Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FTIR), and Thermogravimetric Analysis (TGA). Results demonstrate the feasibility of CNCs synthesis with a yield of 28.1% and 36.9%, and crystallinity of 73.5% and 82.7%. Finally, the morphology and synthesis conditions suggest that this industrial reject fiber (RF) could be used as a source for the CNCs production, thus adding value to the kraft process and opening new possibilities for innovation in the pulp industry.

Development and utilization of lime‐mud waste as filler for production of green paper

In this article, the lime‐mud (LM) as a waste generated in the Kraft pulping process was treated to improve its quality to be utilized again as filler. The final treated LM was characterized by different techniques and compared with the currently used calcium carbonate filler. The laboratory hand sheets were prepared from treated LM and the filler used in the factory with the target filler loads lying in the range 0–10 ash. The effect of filler loads on the physical, optical and mechanical properties of paper sheets was studied and compared with the used filler. The results revealed that the optical properties of paper sheets were greatly improved whereas the mechanical properties decreased. In addition, the best mixture composed of the treated LM and calcium carbonate filler used in Quena paper plant was selected and investigated. © 2018 American Institute of Chemical Engineers Environ Prog, 38:e13022, 2019

Evaluating the production of monosaccharides and xylooligosaccharides from the pre-hydrolysis liquor of kraft pulping process by acid and enzymatic hydrolysis

Pre-hydrolysis liquor (PHL) from the kraft-based dissolving pulp process contains large amounts of hemicelluloses and their degradation products, which makes it a promising candidate for the production of xylose or xylooligosaccharides (XOS). However, it is usually treated as wastewater of the pulp and paper industries. In this study, both acid hydrolysis and enzymatic hydrolysis were applied to prepare xylose and XOS from the PHL, which contained 47.80 g/L of sugars and 14.10 g/L of lignins. Results showed that an optimal xylose yield (30.10 g/L) was obtained at 120 °C for 0.5 h with 4% aqueous sulfuric acid, while the maximum XOS yield (11.63 g/L) was achieved with 0.3% aqueous sulfuric acid at 120 °C for 2.0 h. For the enzymatic hydrolysis, the highest XOS yield of 15.65 g/L was obtained under the optimal condition (60 IU/L PHL, 50 °C, 6 h), and the XOS were mainly composed of xylobiose and xylotriose.

Hydrothermal acid hydrolysis for highly efficient separation of lignin and xylose from pre-hydrolysis liquor of kraft pulping process

In this study, the effect of traditional acidification and hydrothermal acid hydrolysis on the separation of lignin and xylose from the pre-hydrolysis liquor (PHL) of kraft pulping process was comparatively evaluated. The PHL was acidified at room temperature or hydrothermally treated under acidic conditions to isolate lignin and xylose. As compared with the lignin removal rate of 26.8–32.7% by traditional acidification method, a much higher lignin removal rate of 57.1% was achieved by hydrothermal acid hydrolysis. Meanwhile, the content of xylose in the PHL increased dramatically from 7.91 to 13.91–34.82 g/L after the hydrothermal acid hydrolysis. The hydrophilicity of the obtained lignin gradually increased as evidenced by the decrease of the corresponding water contact angel. Additionally, the thermal stability of the lignin sample increased steadily with the increment of acid dosage. The hydrothermal acid hydrolysis provides an effective approach to fractionate lignin and xylose from PHL.

Influence of membrane filtration on extraction and characteristics of lignin from a kraft dissolving pulp mill pre-hydrolysate

During dissolving pulp production, the extraction of hemicellulose and other organics from hardwood chips prior to the kraft pulping process can be performed using steam or hot water. The pre-hydrolysate from this step is rich in sugars and contains a considerable amount of lignin. It is estimated that the lignin content in this stream can be as high as 28 t d−1 for a kraft dissolving pulp mill producing about 550 t d−1 of pulp. In this article, we report on the recovery of lignin and its characterization. The use of a membrane filtration system has been experimentally validated as an effective method for concentrating the pre-hydrolysate and extracting lignin. Three membranes with different molecular weight cut-offs (100, 10 and 1 kDa) have been tested. In a subsequent step, sulfuric acid was added to the concentrated pre-hydrolysate to precipitate the lignin. The recovered lignin was characterized with respect to purity, molecular weight distribution and other chemical properties. Approximately 99% retention of both sugars and lignin was achieved using the 1 kDa membrane, with about 44.4% of the total lignin being extracted by sulfuric acid precipitation method. The lignin was found to have a low molecular weight (2810 Da), high homogeneity (Mw/Mn = 1.15), and high purity (91%). These characteristics make the pre-hydrolysate lignin a very attractive candidate for niche applications.

Dewatering properties of low grammage handsheets of softwood kraft pulps modified to minimize the need for refining

Abstract Previous paper (Rahman et al. 2017) showed that the yield of softwood kraft pulp increased by the addition of either polysulfide or sodium borohydride because of higher hemicellulose retention. An increase in hemicellulose content can make dewatering more difficult as WRV of the pulp increases, but instead, an overall increase in pulp yield could improve dewatering as a sheet of a certain weight will contain fewer fibres, giving a more open sheet structure. It was therefore of interest to measure the dewatering properties of low grammage handsheets (20 g/m2) under conditions mimicking the tissue paper machine dewatering processes, and sheet strength properties, WRV, °SR and fibre dimensions were also studied. The results showed that the positive influence of overall yield increase dominated over the negative influence of an increase in hemicellulose content on the dewatering properties, particularly at lower refining energy levels. Moreover, higher yield and higher hemicellulose content pulps had a higher tensile index at the same dryness. A given tensile index was achieved with less refining energy. The results indicate that increased yield and hemicellulose content by modification of the kraft pulping process will result in a pulp with a potential to improve tissue paper quality.

Enzymatic Hydrolysis Of Olive Industry Solid Waste Into Glucose, The Precursor Of Bioethanol

Olive industry solid waste (OISW) is a by-product generated in the process of olive oil extraction. It is a lignocellulosic material consisting of cellulose, hemicelluloses, lignin and other extractives. In this work, a process for hydrolyzing the OISW into its monomers glucose, the precursor of bioethanol was developed. The hydrolysis process involves two stages: in the first stage, the OISW was activated by treating it with a material that opened the cellulose structure and made it more accessible for chemical reagents. Several activating materials were evaluated among them are water, NaOH, Ca(OH)₂ and acetic acid. In the second stage, the OISW was subjected to an enzymatic treatment which hydrolyzed it into sugar. A combination of the two enzymes cellulase (endo-1,4-β-glucanase) and β-glucosidase was used in the hydrolysis. Best hydrolysis results were obtained at enzymes dose of 15.0 mg of cellulase and 20.0 mg/g of β-glucosidase per one gram of OISW at 45 oC and a pH of 4.8. A yield of 85.02% sugar was obtained from the hydrolysis of 10% NaOH pre-treated OISW under a positive pressure of air. Whereas, hydrolysis of cellulose extracted from OISW by the Kraft pulping process and bleached using DEHP beaching sequence produced about 95.30% sugar.

Technoeconomic assessment of hydrothermal liquefaction oil from lignin with catalytic upgrading for renewable fuel and chemical production

Lignin is a readily available by‐product of the Kraft pulping process, and may be processed via hydrothermal liquefaction (HTL) to produce a bio‐oil suitable for cofeeding into a petroleum refinery hydrotreatment unit. HTL of lignin is performed in near‐critical water and, in addition to the bio‐oil, produces an aqueous organic and solid char phase. The aqueous organics are primarily phenolics, which may be converted into valuable coproducts via liquid–liquid extraction and hydrotreatment to benzene, toluene, ethylbenzene, and xylenes (BTEX) compounds. Three technological scenarios were developed: a current technology case, a state‐of‐the‐art research case, and an optimal case based on product targets provided by refiners. For a large Kraft pulp mill (400 metric tons/day of dry lignin), a renewable fuel production of 65–70 million L/year, with capital costs of $114–125 million and a final per liter cost of $0.41–0.44 were estimated. The BTEX coproduct yield ranged from 16.8–18.0 million L/year. An economic analysis of the process revealed that the hydrotreatment steps have the highest installed capital costs, while the liquid–liquid extraction process is the largest operating cost. Based on these results, the minimum selling price (MSP) of the biofuel is between $3.52 and $3.86/gallon, and the MSP of BTEX is between $1.65 and $2.00 per liter. With current technology, coproduction of BTEX does not offset the cost of biofuel production. Improved technology to further lower bio‐oil oxygen content and decrease both capital and operating costs are needed to make HTL‐based fuels competitive with fossil fuel‐based options.This article is categorized under: Energy Research & Innovation > Science and Materials Bioenergy > Economics and Policy Bioenergy > Systems and Infrastructure

High Yields of Bio Oils from Hydrothermal Processing of Thin Black Liquor without the Use of Catalysts or Capping Agents.

Black liquor (BL) from the kraft pulping process has been treated at elevated temperatures (380 °C) in a batch reactor to give high yields of a bio oil comprising monomeric phenolic compounds that were soluble in organic solvents and mineral oil and a water fraction with inorganic salts. The metal content in the product was <20 ppm after a simple extraction step. A correlation between concentration, temperature, and reaction time with respect to yield of desired product was found. At optimal reaction conditions (treating BL with 16 wt % dry substance at 380 °C for 20 min), the yield of extractable organics was around 80% of the original lignin with less than 7% of char. The product was analyzed by gel permeable chromatography, mass spectroscopy, nuclear magnetic resonance, elemental analysis, and inductively coupled plasma. It was found that a large fraction composed of mainly cresols, xylenols, and mesitols. This process provides a pathway to convert a major waste stream from a pulp mill into a refinery feed for fuel or chemical production, whereas at the same time the inorganic chemicals are recovered and can be returned back to the pulp mill.

Cationic kraft lignin-acrylamide as a flocculant for clay suspensions: 1. Molecular weight effect

Abstract Currently, kraft lignin is burned in the recovery cycle of the kraft pulping process; despite its high potential to be extracted and converted into value-added products. In this work, kraft lignin (KL) was copolymerized with acrylamide (AM) and 2-[(methacryloyloxy) ethyl] trimethylammonium chloride (DMC) to produce cationic copolymers. Copolymers with two different molecular weights of 168,200 g/mol (KAD-1) and 103,000 g/mol (KAD-2), but with a similar charge density of 1.15 meq/g, were selected and the flocculation efficiency of the copolymers in two different clay suspensions was investigated. Suspension pH affected the adsorption of the copolymers on clay particles and the removal of the particles from the suspension. At a 8 mg/g dosage, KAD-1 adsorbed more than KAD-2 as it was larger and thus developed more bridging with clay particles. The size of particles raised from 4.7 for kaolin to 16.3 μm for kaolin/KAD-1 flocs and 15.1 μm for kaolin/KAD-2 flocs, and it increased from 6.1 for bentonite to 18.97 μm for bentonite/KAD-1 flocs and 15.35 μm for bentonite/KAD-2 flocs in the presence of 8 mg/g of copolymers, respectively. The adsorption, zeta potential and flocculation analyses confirmed that KAD-1 was a more effective flocculant than KAD-2. The evidence for the agglomeration of clay particles via bridging and electrostatic patch mechanisms was also discussed in this work.

Thermal Evaluation by DSC and Tensile Strength of Extrudated Blends from Polyethylene Terephthalate and Kraft Lignin

Polyethylene terephthalate is a polymer commonly used in food packaging which recycling potential should be explored with new studies. Lignin is the second most abundant biomass resource in the nature. Kraft lignin is a byproduct of the kraft pulping process, it is produced in large quantities. In this work PET/KL blends were produced in 1, 2, 5, 10 wt% of KL. These polymers were processed by extrusion, aiming to produce an alternative engineering material. Samples were investigated by Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), X-Ray Diffraction (XRD), Scanning Electronic Microscopy (SEM) and Tensile Test. Samples of extruded PET and PET/KL show differences in the pre-crystallization temperature. PET has higher pre-crystallization and melting temperature, as well as higher melting enthalpies. At 140 °C the presence of lignin reorders PET morphology, inducing the increase of the crystalline phase in the systems. The amount of KL in the sample influences also the sample morphology, which can results in a phase separation.