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Factors affecting the free shrinkage of handsheets: apparent density, fines content, water retention value, and grammage, TAPPI JOURNAL June 2018
Factors affecting the free shrinkage of handsheets: apparent density, fines content, water retention value, and grammage, TAPPI JOURNAL June 2018
Journal articles
Magazine articles
Using online bubble size and total dissolved solids measurements to investigate the performance of oxygen delignification, TAPPI JOURNAL June 2018
Using online bubble size and total dissolved solids measurements to investigate the performance of oxygen delignification, TAPPI JOURNAL June 2018
Journal articles
Magazine articles
Accelerated aging of bio-oil from lignin conversion in subcr
Accelerated aging of bio-oil from lignin conversion in subcritical water, TAPPI JOURNAL March 2017
Journal articles
Magazine articles
Analysis of economically viable lignin-based biorefinery st
Analysis of economically viable lignin-based biorefinery strategies implemented within a kraft pulp mill, TAPPI JOURNAL March 2017
Journal articles
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Pulp and paper mills: The original biorefineries — past performance and limitations to future opportunities, TAPPI Journal October 2023
ABSTRACT: Pulp mills have been biorefineries since the invention of the Tomlinson recovery boiler. Unfortunately, the paper industry has done a poor job explaining that concept to the general public. A number of bioproducts in everyday use have been produced by pulp mills for several decades, and new products are routinely being developed. Modern research efforts over the last couple of decades have focused on producing even more products from pulp and paper mills through capacity enhancement and the development of value-added products and liquid transportation fuels to enhance paper mill profitability. Some of these efforts, often referred to as modern biorefineries, have focused so heavily on product development that they have ignored operating and process realities that limit the transformation of pulp and paper mills from the current limited number of bioproducts produced today to economic scale production of these value-added products. In this paper, several of these limitations are addressed. In addition, there are several supply chain, marketing, product quality, and economic realities limiting the value potential for these wholesale conversions of pulp mills into multiproduct modern biorefineries. Finally, the conservative nature and capital intensity of the pulp and paper industries provide a difficult hurdle for conversion to the modern biorefinery concept. These issues are also reviewed.
Journal articles
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Kraft pulp viscosity as a predictor of paper strength: Its uses and abuses, TAPPI Journal October 2023
ABSTRACT: For bleached kraft pulps, two factors govern paper strength: the individual fiber strength, and the bond strength that adheres the individual fibers together in the paper matrix. Inherent fiber strength is related to the length of the carbohydrate polymers, also known as the degree of polymerization (DP). Average DP (DP) is inferred by performing pulp viscosity measurements. Under certain circumstances during kraft pulping and bleaching, the average polymer lengths can be shortened, resulting in lower pulp viscosity, and may indicate fiber damage. Fiber damage typically manifests itself as a reduction in tear strength for well-bonded handsheets.This paper will review the literature on how pulp viscosity can predict paper/fiber strength and how it can be used as a diagnostic tool. It can be a means to monitor pulp quality during pulping and bleaching, as well as to alert when such operations approach a critical threshold. However, viscosity losses must be carefully and judiciously analyzed. Like most diagnostic tools, viscosity measurements can be misused and abused, which can lead to incorrect inferences about intrinsic fiber strength. This review will also cover these misuses. The overall goal is to provide the papermaker a better understanding of what pulp viscosity is, how it correlates to potential sheet strength, and what its limitations are. It will be illustrated that when pulp viscosity drops below a critical value, it will indicate an appreciable deterioration in the paper’s tear and tensile strength.
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A true green cover for industrial waste landfills, TAPPI Journal April 2024
ABSTRACT: Greenhouse gas (GHG) emissions in the United States totaled 5,981 million metric tons of carbon dioxide equivalent (MMT CO2eq) in 2020. Of that, GHG emissions by the pulp and paper sector amounted to 35 MMT CO2eq direct emissions and those by industrial waste landfills summed to 7.4 MMT CO2eq direct emissions. Loss of GHG sinks due to change in land use further contributes to the net GHG emissions. Industrial waste landfills are typically required to comply with certain federal and state regulations, including meeting requirements for final cover systems. Conventional final cover systems have included use of soil covers and/or soil-geosynthetic composite covers. An engineered turf cover provides for an excellent “green” alternative final cover system for industrial waste landfills.This paper discusses various sustainability aspects pertaining to use of an engineered turf final cover, including: (i)significantly low carbon footprint associated with the construction of an engineered turf alternative final coverwhen compared to closure using a traditional or prescriptive cover system; (ii) saving valuable soil and land resourc-es; (iii) saving water resources by reduction in its use during and after construction; (iv) reducing impacts associated with borrow areas; and (v) reducing overall carbon footprint. Further, when using an engineered turf cover, opportunities exist for beneficial reuse of land, including development of solar energy. A brief discussion on the potential fordevelopment of solar energy is included.
Journal articles
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Surface modification of TiO2 with MPS and its effects on the wettability and physical properties of Kawayan Kiling (Bambusa vulgaris Schrad ex. Wendl) handsheets, TAPPI Jouranl April 2024
ABSTRACT: The need for hydrophobic papers has steadily increased over past years. These papers are often sought after as packaging materials and have high demand in the food industry and medicine. In this study, various concentrations of surface-modified TiO2-MPS were added to Kawayan Kiling (B. vulgaris) pulp at the wet-end section of handsheet formation. Surface-modified TiO2-MPS was made from nano-titanium (IV) oxide using 3-(trimethoxysilyl)propyl methacrylate as a coupling agent. The wettability of handsheets and physical properties were tested using various standard methods. Results reveal that the handsheets without surface-modified TiO2-MPS had the lowest water contact angle (WCA), while the handsheet with 12.34% (w/w) surface-modified TiO2-MPS had the highest WCA. At 17% (w/w) surfacemodified TiO2-MPS, the WCA rapidly declined. Handsheets with surface-modified TiO2-MPS have a rougher surface compared to the handsheets without chemicals and handsheets with unmodified TiO2. This roughness made the handsheet hydrophobic. The handsheet with 12.34% (w/w) unmodified TiO2 has a smoother surface than the control handsheet. Energy-dispersive X-ray spectroscopy (EDS) analysis shows that the handsheet with 12.34% (w/w) unmodified TiO2 contained titanium, while the handsheet with 12.34% (w/w) surface-modified TiO2-MPS contained both titanium and silicon. Generally, the physical properties of handsheets improved with surface-modified TiO2- MPS, especially grammage, bulk thickness, tensile index, and water absorptiveness, which showed statistically significant differences across treatments. The tear index did not differ between treatments.
Journal articles
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Sulfur makeup in an unbleached kraft pulp mill, TAPPI Journal August 2024
ABSTRACT: Sodium sesquisulfate or “sesqui” (Na3H(SO4)2) is a by-product of chlorine dioxide production at kraft pulp mills. It is typically used for sodium and sulfur makeup in the liquor loop. Mondi Hinton Inc. (MHI) in Hinton, AB, Canada, was converting from bleached to unbleached kraft pulp production and was thus losing this source of makeup. The only option that was readily available as a substitute was sodium hydrosulfide (NaHS), which was cost prohibitive. Other options such as sodium sulfate (Na2SO4), emulsified sulfur, sulfuric acid (H2SO4), and sodium bisulfite (NaHSO3) were compared. The mill concluded that pelletized sulfur plus sodium hydroxide or “caustic soda” (NaOH) was the best option. Laboratory-scale experiments showed that pelletized sulfur dissolved in white liquor (WL). A mill-scale trial revealed that pelletized sulfur added to a causticizer had no adverse impacts on the downstream pressure filters or kiln operation. The sulfur reacted to produce polysulfide upstream of the WL storage tank, giving the liquor an orange hue. This polysulfide appeared to partially degrade into thiosulfate before being fed to the digester. The heavy black liquor (HBL) sulfur:sodium (S:Na) ratio did not change significantly, even though the sulfur/soda addition location was upstream of the original one. In addition, other properties such as liquor heating value and elemental analysis did not significantly change. Due to polysulfide/thiosulfate concentration in the white liquor, it was determined that the carbon steel equipment was at risk for corrosion. During the annual turnaround that occurred eight months after the addition of sulfur was started, the wash zone of the digester showed no signs of thinning/damage. The mill has been running exclusively with pelletized sulfur for 22 months (as of August 2024), realizing significant cost savings compared to the use of NaHS or other sulfur/soda addition options.
Journal articles
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Next generation dry strength additives: Leveraging on-site synthesis to develop high performance glyoxalated polyacrylamides, TAPPI Journal January 2024
ABSTRACT: Although glyoxalated polyacrylamides (gPAMs) have been described since the 1950s, the freedom to design new materials based on this chemistry has been limited by practical concerns; namely, a balance between solution concentration and material characteristics must be met to make the economics of gPAM strength additives work for the paper industry. For traditional “delivered” gPAMs, only a very narrow range of polyacrylamide molecular weights and compositions could be considered for glyoxalation. However, the development and successful implementation of automated reactor equipment that allows for the synthesis of gPAMs from glyoxal and polyacrylamide copolymers at the mill, known as “on-site” glyoxalation, obviates the shipping and stability concerns that have traditionally held back gPAM development. As such, on-site generators represent a platform that enables the glyoxalation of materials that would otherwise not have been suitable for use in a traditionally delivered gPAM product. These on-site generators therefore open new avenues for polymer design to allow for the creation of the next generation of strength additives. By leveraging the synthetic freedom of the on-site generators, a suite of high performance gPAMs has been designed, yielding materials that provide both exceptional strength and drainage performance in poor quality furnishes.