Search
Use the search bar or filters below to find any TAPPI product or publication.
Filters
Content Type
Publications
Level of Knowledge
Committees
Collections
Journal articles
Editorial: TAPPI Journal research themes in 2025 highlighted sustainability and process efficiency, TAPPI Journal February 2026
Each year, the pages of TAPPI Journal offer more than a collection of technical papers -- they provide a sanpshot of where our industry is appling its intellectual energy in research. Looking back at the January through November 2025 issues, there was a distant focus on improving materials performance, strenghtening process efficiency, and integrating sustainability considerations into existing manucaturing processes. A majority of this focus was centered on packaging for a variety of applications.
Journal articles
Beyond the machine: Decoding process water microbes behind odor in papermaking, TAPPI Journal February 2026
ABSTRACT: Paper manufacturing processes create an ecosystem conducive to microbial growth, characterized by abundant water, nutrients, and optimal temperatures, fostering diverse microbial habitats. With the increased use of recycled fibers and greater water system closure, the industry now faces amplified microbiological challenges, particularly odor generation. These odor problems have raised community concerns, as shown by resident com-plaints, and have led to significant economic impacts, including costly lawsuits against major paper manufacturers. Based on earlier studies showing that microbes in papermaking systems can generate odor-causing volatile com-pounds, this study is guided by the hypothesis that recycle paper mill process water harbors odor-causing microbial communities and thus represents a primary source of malodor. To test this hypothesis, process water samples from commercial recycle paper mills were analyzed using high-throughput Illumina sequencing to characterize microbial communities in one complete analysis. The study results revealed fifteen major microbial populations, dominated mainly by the genus Pseudomonas. The identified microbes were further linked to prior literature to determine their functional roles in odor generation, including the production of haloanisoles (2-monochloroanisole, 2,4-dichloroanisole, 2,3,6-trichloroanisole, 2,4,6-tri-bromoanisole), geosmin, 2-methylisoborneol, and volatile organic sulfur compounds such as dimethyl polysulfides, hydrogen sulfide, and methylmercaptan. This study introduces a microbiological community-profiling approach that enables papermakers to assess whether process water represents a potential source of malodor. Earlier studies have not examined microbial com-munities in recycle paper mill process water specifically from the perspective of identifying malodor sources, nor have they integrated such findings with an extensive literature-based assessment. The findings of this study advance both science and practice by offering a method that can serve as an early diagnostic tool for papermakers, supporting effective future odor management and deepening understanding of microbial ecology in paper mill environments.
Journal articles
Utilization of inline total dissolved solids measurement system in a pulp mill's brownstock washing line, TAPPI Journal January 2026
ABSTRACT: Efficient washing improves the recovery of sodium (Na) and sulfur (S) cooking chemicals, as well as wood-based dissolved organic material. It also reduces the additional consumption of chemicals in the subsequent bleaching stages. The operation of the brownstock washing of the pulp mill’s fiber line has a significant impact on the mill’s energy economy, material efficiency, and environmental emissions. Process refractometers can be used to measure the total dissolved solids (TDS) from both the washing liquor and the pulp suspension filtrate part directly from pipelines or pipe bypass loops. In addition, by measuring the three or four incoming/outgoing dissolved solids streams to the washers, together with consistencies and flow rate measurements, it is possible to build the real-time effectiveness calculation of the washer(s). In this work, an online efficiency calculation based on TDS measurements was built for a pressure filter after cooking and oxygen (O2) delignification. The washing performance was monitored over a longer period, and stepwise tests were conducted to find the optimal operating mode. The feed and washing consistencies, the washer’s torque, and the washing liquid distributions varied, and the washer’s efficiency values were monitored using realtime measurements. From the long-term trends of the efficiency calculation, process disturbances could be detected, and their causes could be found. Based on the results of the stepwise tests, an optimal operating model for the washer was found. By optimizing the washing consistency, the Y10 washing yield could be increased. More efficient washing with the same or even a smaller amount of washing liquid can relieve the operation of the evaporator, which is often a bottleneck in the mill. The study also found the effect of cooking-related carryover on the operation of the oxygen stage, as well as differences in the washability of softwood and hardwood.
Journal articles
Towards closed water systems in chemical pulp mills: Evaporation of acidic filtrate from ECF bleaching with high chloride content, TAPPI Journal January 2026
ABSTRACT: In modern bioproducts mills utilizing elemental chlorine-free (ECF) bleaching, the bleaching process is the primary effluent source. The pulp bleaching typically generates 10 m³/a.d. metric ton of acidic filtrate. Despite extensive studies on recycling methods, the acidic filtrate is still typically directed to wastewater treatment plants due to the challenges created by its volume and chloride content. Recently, the volume of acidic filtrate has significantly decreased to 5 m³/a.d. metric ton, reducing the capacity required for the recycling process closer to a feasible level. In this study, we investigated recycling of acidic filtrate by evaporation from the D0 stage of a D0-Eop-D1 bleaching sequence. In the mill, hydrochloric acid (HCl) was used for pH control instead of sulfuric acid (H2SO4) due to better control of precipitation. This arrangement substantially changes the composition of the acidic filtrate, increasing the chloride (Cl-) and decreasing the sulfate (SO4 2-) ionic content. For the above reasons, it is necessary to study the effect of evaporation on the quality of the resulting condensate and concentrate. The results provide new information on how to close water loops in a modern bioproducts mill with higher Cl- content as one option. The results show that the evaporation of the high-chlorine D0 filtrate produces a pure condensate with methanol as the main component. Only small amounts of Cl- were observed in the condensate. The majority of chlorine (Cl) compounds remains as dissolved compounds in the evaporated concentrate when the dry solids content of the concentrate is ~10%. The Cl compounds in the concentrate can be converted to sodium chloride (NaCl) by incineration.
Journal articles
Effects of calcium on sodium salt scaling with the presence of resin acids and fatty acids, TAPPI Journal June 2026
ABSTRACT: Reintroducing tall oil soap or its related products into high dry solids black liquor has been found to reduce sodium salt scaling in falling film evaporators. Aside from resin acids and fatty acids, which are the likely scale inhibitors, calcium is reintroduced into black liquor because of the relatively high calcium content of tall oil soap. One concern is that this increase in calcium content might lead to the formation of additional calcium and sodium scales in evaporators. In this work, we investigated the relationship among trace amounts of calcium, sodium salts, resin acids, and fatty acids in a controlled system using a model salt solution and a benchtop setup. We studied the effects of the calcium carbonate addition and calcium carbonate scales on sodium salt scaling in the presence of resin acids and fatty acids. We found that some calcium carbonate is incorporated in the precipitated sodium crystals, and the suspended sodium crystals become larger and more compact with increasing calcium carbonate concentration. Experiments in the benchtop setup show that precipitating calcium carbonate scale on the heat exchanger does not lead to a higher rate of sodium salt scaling. The solubility of calcium carbonate is not affected by the addition of resin acids and fatty acids. These findings indicate that the reduction in sodium salt scaling through the addition of tall oil soap is primarily related to resin acids and fatty acids, rather than to calcium or to interactions between calcium and mixtures of resin and fatty acids.
Journal articles
Optimization of optical coverage of board surfaces with assessment of light scattering and absorption using mineral as a coating component, TAPPI Journal June 2026
ABSTRACT: One of the primary functions of mineral inclusion into paper or paperboard is to improve the optical performance of the substrate. A coating may be applied to a sheet in order to cover a dark base, to improve the sheet opacity, to give the correct smoothness and gloss, or to give a suitable surface on which to print. The brightness of a pigment has long been used as a guide for pigment choice in paper and board. However, the measured paper brightness is a function of color and light absorption (K) of the coating and base and the light scattering (S) within the sheet resulting from interfaces with different refractive index. The optical performance can be quantified by measuring the S&K coefficients as described by the Kubelka-Munk model/theory in a filled or coated paper sheet. In coating, this is often assessed as a function of coat weight, and the corresponding physical sheet properties are assessed at the same time; for example, the correct gloss, smoothness, point-to-point uniformity, and printability. The optical performance in the sheet is often not directly related to the pigment brightness, but is largely a function of the particle packing within the sheet and coating layer. In the first and second main sections of this work, respectively, we show how S&K calculations from the Kubelka- Munk equations can be used in coated sheets to determine the optical performance and how this can be used as a predictive tool for the final sheet performance. This is presented for base sheets with different starting brightness. The third section of this work focuses on how mineral combinations in coatings can be used to improve the light scattering and consequently the optical performance of the board. We include theoretical considerations and then finally share a case study for improvement on the optical properties of recycled board.
Journal articles
Preparation of a vegan leather from mycelium with papermaking method, TAPPI Journal June 2026
ABSTRACT: With growing concern over the environmental impacts of both natural leather and conventional synthetic leathers, the development of sustainable and eco-friendly leather alternatives has become an urgent research priority. In this study, an innovative wet papermaking strategy is proposed to fabricate continuous, homogeneous mycelial sheets from chitin-rich fungal mycelium, mimicking the matrix structure of genuine leather. These mycelial sheets were chemically modified to meet the performance requirements of leather foam layers. Subsequently, the modified mycelial sheets were combined with a substrate fabric to produce a novel mycelium-based leather composite (myco-paper leather) that achieves an excellent balance of mechanical properties and tactile qualities. Experimental results demonstrate that the mycelium-sheet-based leather substitute exhibits remarkable mechanical performance, with a tensile strength of approximately 45 MPa and an elongation at break of about 10.5%. After lamination with the substrate fabric, the composite material shows a tear strength of approximately 16 N, along with a desirable hand feel and surface texture. Following tannic acid tanning, the mycelial sheets also exhibit significant antimicrobial and antifungal properties, forming an inhibition zone of approximately 2 mm against Staphylococcus aureus. Through reinforcement with plant fibers, the developed material attains both strength and flexibility, indicating that the wet papermaking of mycelial sheets is a feasible and scalable approach for producing sustainable leather alternatives. This work not only employs a simple and mature papermaking process to process fungal mycelium but also provides a new conceptual and practical foundation for the large-scale production of bio-based leather substitutes. The findings have significant implications for advancing a low-carbon, sustainable leather industry.
Journal articles
Investigation of the factors contributing to malodorous gases emission during secondary fiber reuse, TAPPI Journal June 2026
ABSTRACT: Malodorous gases are commonly produced during secondary fiber reuse, which is harmful to human health and causes environmental pollution. This paper investigated the influence of fiber type and concentration, temperature, and whitewater concentration on the malodorous gases. The results indicated that, in pulp prepared with fresh water, bleached hardwood kraft pulp (LBKP) did not produce malodorous gases after standing for five days. In contrast, the secondary fiber began to release substantial amounts of total volatile organic compounds (TVOC) on the third day and hydrogen sulfide (H2S) and ammonia (NH3) on the sixth day, and black substances began to appear in the pulp, which proved that the microorganisms began to proliferate. With the increase of the secondary fiber concentration, the release amounts of TVOC, H2S, and NH3 gradually rose, along with the black substances in the pulp. With increased temperature, the release of TVOC increased steadily, while the release of H2S and NH3 reached the maximum at about 45°C, and then began to decline. The decrease of the pulp freeness accelerated the generation of the malodorous gases, but the total release amounts of TVOC, H2S, and NH3 were basically the same. With the increase of white water concentration, the release of TVOC, H2S, and NH3 increased rapidly. When the white water/fresh water was 20 mL/80 mL, the slurry changed from pale yellow to aterrimus on the sixth day. Therefore, microorganisms in the secondary fiber caused pulp deterioration, while white water was the main reason for generating a large amount of malodorous gases.
Journal articles
Permeability simulation for filled paper based on three-dimensional structural model developed by X-ray computed tomography scanning, TAPPI Journal March 2026
ABSTRACT: In this study, an in-depth exploration of filled paper was conducted to understand its structural and permeability characteristics. Cotton linter pulp and precipitated calcium carbonate (PCC) filler were utilized to prepare pure fiber paper, and PCC1 and PCC2 filled papers with different filler particle sizes. Then, the pore structure parameters of paper samples were characterized by mercury intrusion porosimetry, and the X-ray computed tomography (X-CT) scanning was carried out. Subsequently, the 3D microstructures were established based on the X-CT slice images, and the filler characteristic parameters and filler 3D distribution were quantitatively analyzed. Finally, permeation simulations in the thickness and horizontal directions were performed. The findings indicate that filling changes the paper porosity, and the pore tortuosity varies with direction. The estimated pore•throat radius distribution shows specific patterns for different papers. The fillers have different distribution characteristics in the paper samples. Moreover, the paper permeability differs with direction, with smallsized filler having a significant impact on fluid penetration in the thickness direction. Overall, this study provides an effective method for investigating internal paper filler and its distribution, which contributes to the understanding of paper structure•performance relationships.
Journal articles
Moisture performance of silica-paper hybrids in the hygroscopic range, TAPPI Journal March 2026
ABSTRACT: Vapor retarders, crucial in building constructions, are traditionally made from plastic-based materials, raising environmental concerns due to the use of fossil materials. This study explores the potential of functionalized papers, particularly silica-paper hybrids, as sustainable alternatives. This work delves into the moisture properties of sol-gel coated linter papers, considering the water vapor permeability and physisorption behavior following DIN EN ISO 12572 and DIN EN ISO 12571. The study addresses hysteresis, noting the lower hysteresis of mesoporous coatings in comparison to dense coatings and implying benefits in moisture release. Findings underscore the need for a nuanced understanding of coating characteristics and their impact on sorption. In order to better assess the relationship between the coating content of the papers and their specific sorption properties, further investigations, such as the measurement of specific surface properties (e.g., specific surface area), are required. The findings of the water vapor diffusion resistance measurement study demonstrate a correlation between the observed resistance and the vapor levels. The results show that the water vapor diffusion resistance is elevated at lower vapor levels when compared to higher levels. This particular material behavior is typically employed within the construction industry for the utilization of moisture-variable water vapor retarders. The silica-paper hybrids exhibit a response that indicates the potential for advancement into a moisture-variable water vapor barrier.