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Probing the molecular weights of sweetgum and pine kraft lignin fractions, TAPPI Journal June 2021
ABSTRACT: The present investigation undertook a systematic investigation of the molecular weight (MW) of kraft lignins throughout the pulping process to establish a correlation between MW and lignin recovery at different extents of the kraft pulping process. The evaluation of MW is crucial for lignin characterization and utilization, since it is known to influence the kinetics of lignin reactivity and its resultant physico-chemical properties. Sweetgum and pine lignins precipitated from black liquor at different pHs (9.5 and 2.5) and different extents of kraft pulping (30–150 min) were the subject of this effort. Gel permeation chromatography (GPC) was used to determine the number average molecular weight (Mn), mass average molecular weight (Mw), and polydispersity of the lignin samples. It was shown that the MW of lignins from both feedstocks follow gel degradation theory; that is, at the onset of the kraft pulping process low molecular weight-lignins were obtained, and as pulping progressed, the molecular weight peaked and subsequently decreased. An important finding was that acetobromination was shown to be a more effective derivatization technique for carbohydrates containing lignins than acetylation, the technique typically used for derivatization of lignin.
Journal articles
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New learnings and strategies for meeting future recovery boiler particulate emission limits with existing electrostatic precipitators, TAPPI Journal June 2021
ABSTRACT: It is foreseeable that recovery boiler particulate emission limits in the United States and Canada will continue to get more stringent with time. Because of this, continued improvement of emission control equipment, as well as a better understanding of how operating parameters affect performance, are necessary. Although electrostatic precipitators (ESPs) are often viewed as a mature technology, many improvements in ESP technology continue to be developed. In recent years, academic efforts have improved the understanding of recovery boiler operating conditions on ESP performance. Additionally, advancements in materials, power supplies, and design continue to improve the efficiency and reliability of ESPs.This paper discusses how recovery boiler and electrostatic precipitator (ESP) operating factors affect ESP perfor-mance based on process simulations and practical experience, and how these learnings can be implemented to improve future operation of existing ESPs.
Journal articles
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Editorial: Agility and adaptation in a dynamic business world, TAPPI Journal January 2021
ABSTRACT: As we move into 2020, it's interesting to look back at the research topics that were covered in TAPPI Journal (TJ) the previous year. Members of the TJ editorial board organized diverse special issues on lignin, coating ,forming, and diverse papermaking and biorefinery topics, which are discussed in the following sections.
Journal articles
Magazine articles
Editorial: Risks and rewards of research during a pandemic, TAPPI Journal August 2020
ABSTRACT: For universities and research institutions, the arrival of Covid-19 last spring halted activities around the world while exposing the need for detailed Public Health Emergency (PHE) plans to cope with a highly-contagious virus in laboratory and classroom settings. As classroom work switched to online platforms like Zoom, the reality set in that long-term plans were needed to safely keep students learning, research flowing, and universities financially stable.
Journal articles
Magazine articles
Modeling of the energy of a smelt-water explosion in the recovery boiler dissolving tank, TAPPI Journal August 2020
ABSTRACT: The explosion energy generated as molten smelt droplets interact with water was evaluated as a function of smelt distribution, water temperature, and smelt temperature using a thermodynamic model. The results show that increasing smelt-to-water volume ratio and water temperature significantly increases the explosion energy, converting a larger proportion of the thermal energy of smelt into mechanical work. To reduce the chance of violent smelt-water explosions, it is important to: i) optimize the shatter jet design and operation to uniformly distribute the smelt over a large area in the dissolving tank; ii) avoid high green liquor temperature and ensure adequate liquor mixing; and iii) avoid upsets that may cause heavy smelt runoff or jellyroll smelt.
Journal articles
Magazine articles
Editorial: Snapshot from the pandemic: TAPPI Journal Editorial Board shares their experiences, TAPPI Journal April 2020
ABSTRACT: In this most serious time of the global COVID-19 pandemic, I and TAPPI staff have been fortunate to work remotely and practice social distancing. The same goes for our Editorial Board. Still, the business of papermaking has continued, and those on our Board who support the industry through their work and research have had to make adjustments. Here, members of the Editorial Board share their experiences of working during the pandemic. As we all anticipate returning to a new normal that once again allows face-to-face interaction, we hope our TAPPI Journal readers stay safe and healthy as we all personally and professionally navigate this challenging time.
Journal articles
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Papermaking properties of bacterial nanocellulose produced from mother of vinegar, a waste product after classical vinegar production, TAPPI Journal April 2020
ABSTRACT: Bacterial nanocellulose (BNC) has gained a lot of attention in recent years due to its nano-size-derived properties. Although it is essentially chemically similar to plant-derived cellulose, it has smaller size and is enriched in free hydroxyl groups, which greatly improve mechanical properties of reinforced paper. However, although BNC has some unique features, it comes at a high price. In this paper, we introduce a new solution for BNC production. We have isolated bacterial nanocellulose directly from agro-industrial waste—mother of vinegar—and used it in the production of paper sheets. We show here that paper sheets made with the addition of only 10% bacterial nanocellulose from mother of vinegar substantially improved basic mechanical as well as printing properties of paper.
Journal articles
Magazine articles
Creasing severity and reverse-side cracking, TAPPI Journal April 2020
ABSTRACT: Crease cracking can be detrimental to the functionality and appearance of paperboard-based packaging. The effect of creasing severity on the degree of reverse-side crease cracking (bead-side of the crease) of paperboard was investigated. Samples were creased with a range of rule and channel geometries, and the cracking degree was quantified as the percent of cracked length relative to the total length of the crease. The cracking degree was typically below 5% at low crease penetration depths, but was exponentially higher beyond a critical penetration depth. A rule and channel combination with a wider clearance shifted the critical depth to larger values. The creasing severity parameter, termed the creasing draw, converged the cracking degree data from different rule and channel combinations to a single curve. The creasing draw was derived from the same analytical expres-sions as the transverse shear strain and quantifies the length of paper that is drawn into the channel during creasing. The critical draw is defined as the draw at which cracking becomes greater than 5%, which corresponds with the point at which cracking becomes exponential. The critical draw is a material/system parameter that defines the level below which cracking is minimal.
Journal articles
Magazine articles
Fate of phosphorus in the recovery cycle of the kraft pulping process, TAPPI Journal March 2020
ABSTRACT: The accumulation of nonprocess elements in the recovery cycle is a common problem for kraft pulp mills trying to reduce their water closure or to utilize biofuels in their lime kiln. Nonprocess elements such as magnesium (Mg), manganese (Mn), silicon (Si), aluminum (Al), and phosphorus (P) enter the recovery cycle via wood, make-up chemicals, lime rock, biofuels, and process water. The main purge point for these elements is green liquor dregs and lime mud. If not purged, these elements can cause operational problems for the mill. Phosphorus reacts with calcium oxide (CaO) in the lime during slaking; as a result, part of the lime is unavailable for slaking reactions. The first part of this project, through laboratory work, identified rhenanite (NaCa(PO4)) as the form of P in the lime cycle and showed the negative effect of P on the availability of the lime. The second part of this project involved field studies and performing a mass balance for P at a Canadian kraft pulp mill.
Journal articles
Magazine articles
Synthesis of filtrate reducer from biogas residue and its application in drilling fluid, TAPPI Journal March 2020
ABSTRACT: Biogas residues (BR) containing cellulose and lignin are produced with the rapid development of biogas engineering. BR can be used to prepare the filtrate reducer of water-based drilling fluid in oilfields by chemical modification. BR from anaerobically fermenting grain stillage was alkalized and etherified by caustic soda and chloroacetic acid to prepare filtrate reducer, which was named as FBR. The long-chain crystalline polysaccharides were selected as dispersing agents (DA), and the water-soluble silicate was used as the cross-linking agent. After the hot rolling of FBR in saturated saltwater base mud for 16 h at 120°C, the filtration loss was increased from 7.20 mL/30 min before aging to 8.80 mL/30 min after aging. Compared with the commercial filtrate reducers, FBR had better tolerance to high temperature and salt, and lower cost.