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A model black liquor formulation for use in development and evaluation of membranes for concentrating weak black liquor, TAPPI Journal February 2022
ABSTRACT: As part of a larger program to develop robust membranes for concentrating weak black liquor prior to the evaporation step, several commercially available membranes were tested for suitability in this application. Given the variation in kraft black liquor for various wood species, the mill-to-mill variations, and the challenges of obtaining fresh samples, the need became apparent for a synthetic reference black liquor that would allow any membrane developer to test a new prototype membrane and compare the results with others. We present a formulation for a model black liquor (MBL) similar to real kraft black liquor in the composition of the major species that can be formulated from readily available reagents. The MBL was tested with two commercial membranes and resulted in similar levels of lignin retention as the real black liquor. It also showed similar viscosity behavior to real black liquor as a function of solids content.
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Editorial: TAPPI Standards development: Authors and reviewers are welcome, TAPPI Journal July 2021
ABSTRACT: Readers of TAPPI Journal (TJ) and those involved with R&D and process and product quality will be familiar with TAPPI Standard Test Methods. These test methods are necessary for validating research and ensuring the quality of end products. In addition to test methods, TAPPI also publishes information that isn’t directly related to test methods, such as technical information and definitions, which include specifications, guidelines, and glossaries. All Standards information is developed with the consensus of a technical working group that adheres to set procedures.
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Lignin-based resins for kraft paper applications, TAPPI Journal November 2019
ABSTRACT: We investigated miscanthus (MS) and willow (W) lignin-furfural based resins as potential reinforce-ment agents on softwood and hardwood kraft paper. These resins might be sustainable alternatives to the commercial phenolformaldehyde (PF) resins. Phenol is a petrochemical product and formaldehyde has been classified as a carcinogen by the U.S. Environmental Protection Agency. The lignin used in this study was derived from hot water extraction (160ºC, 2 h) of MS and W biomass, and may be considered sulfur-free. These biorefinery lignins were characterized for their chemical composition and inherent properties via wet chemistry and instrumental techniques. The resin blends (MS-resin and W-resin) were characterized for their molecular weight, thermal behavior, and mechanical properties. Mechanical properties were measured by the resin’s ability to reinforce softwood and hard-wood kraft papers. The effect of adding hexamethylenetetramine (HMTA), a curing agent, to the resin was also examined. Mixtures of PF and lignin-based resins were investigated to further explore ways to reduce use of non-renewables, phenol, and carcinogenic formaldehyde. The results show that lignin-based resins have the potential to replace PF resins in kraft paper applications. For softwood paper, the highest strength was achieved using W-resin, without HMTA (2.5 times greater than PF with HMTA). For hardwood paper, MS-resin with HMTA gave the highest strength (2.3 times higher than PF with HMTA). The lignin-based resins, without HMTA, also yielded mechanical properties comparable to PF with HMTA.
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Boosting the elongation potential of paper by mechanical refining and additives, TAPPI JOURNAL September 2018
Boosting the elongation potential of paper by mechanical refining and additives, TAPPI JOURNAL September 2018
Journal articles
Magazine articles
Investigation of the influencing factors in odor emission from wet-end white water, TAPPI Journal October 2020
ABSTRACT: Emission of malodorous gases, such as volatile organic compounds (VOCs), hydrogen sulfide (H2S), and ammonia (NH3) during pulping and papermaking has caused certain harm to the air environment and human health. This paper investigated the influencing factors of odor emission from wet-end white water during the production of bobbin paper in a papermaking mill using old corrugated containers (OCC) as raw material. The concentration of malodorous gases emitted from wet-end white water was determined with pump-suction gas detectors. The results indicated that low temperature could limit the release of malodorous gases from white water. Specifically, no total volatile organic compounds (TVOC), H2S, and NH3 was detected at a temperature of 15°C. The concentrations of malodorous gases were slightly increased when temperature increased to 25°C. When temperature was 55°C, the released concentrations of TVOC, H2S, and NH3 were 22.3 mg/m3, 5.91 mg/m3, and 2.78 mg/m3, respectively. Therefore, the content of malodorous gases significantly increased with the temperature increase. The stirring of white water accelerated the release of malodorous gases, and the release rate sped up as the stirring speed increased. However, the total amount of malodorous gases released were basically the same as the static state. Furthermore, the higher the concentration of white water, the greater the amount of malodorous gases released. The pH had little influence on the TVOC release, whereas it significantly affected the release of H2S and NH3. With the increase of pH value, the released amount of H2S and NH3 gradually decreased. When pH reached 9.0, the release amount of H2S and NH3 was almost zero, proving that an alkaline condition inhibits the release of H2S and NH3.
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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.
Journal articles
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Can carbon capture be a new revenue opportunity for the pulp and paper sector?, TAPPI Journal August 2021
ABSTRACT: Transition towards carbon neutrality will require application of negative carbon emission technologies (NETs). This creates a new opportunity for the industry in the near future. The pulp and paper industry already utilizes vast amounts of biomass and produces large amounts of biogenic carbon dioxide. The industry is well poised for the use of bioenergy with carbon capture and storage (BECCS), which is considered as one of the key NETs. If the captured carbon dioxide can be used to manufacture green fuels to replace fossil ones, then this will generate a huge additional market where pulp and paper mills are on the front line. The objective of this study is to evaluate future trends and policies affecting the pulp and paper industry and to describe how a carbon neutral or carbon negative pulp and paper production process can be viable. Such policies include, as examples, price of carbon dioxide allowances or support for green fuel production and BECCS implementation. It is known that profitability differs depending on mill type, performance, energy efficiency, or carbon dioxide intensity. The results give fresh understanding on the potential for investing in negative emission technologies. Carbon capture or green fuel production can be economical with an emission trade system, depending on electricity price, green fuel price, negative emission credit, and a mill’s emission profile. However, feasibility does not seem to evidently correlate with the performance, technical age, or the measured efficiency of the mill.
Journal articles
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Modeling and parameter optimization of the papermaking processes by using regression tree model and full factorial design, TAPPI Journal February 2021
ABSTRACT: One of the major challenges in the pulp and paper industry is taking advantage of the large amount of data generated through its processes in order to develop models for optimization purposes, mainly in the papermaking, where the current practice for solving optimization problems is the error-proofing method. First, the multiple linear regression technique is applied to find the variables that affect the output pressure controlling the gap of the paper sheet between the rod sizer and spooner sections, which is the main cause of paper breaks. As a measure to determine the predictive capacity of the adjusted model, the coefficient of determination (R2) and s values for the output pressure were considered, while the variance inflation factor was used to identify and eliminate the collinearity problem. Considering the same amount of data available by using machine learning, the regression tree was the best model based on the root mean square error (RSME) and R2. To find the optimal operating conditions using the regression tree model as source of output pressure measurement, a full factorial design was developed. Using an alpha level of 5%, findings show that linear regression and the regression tree model found only four independent variables as significant; thus, the regression tree model demonstrated a clear advantage over the linear regression model alone by improving operating conditions and demonstrating less variability in output pressure. Furthermore, in the present work, it was demonstrated that the adjusted models with good predictive capacity can be used to design noninvasive experiments and obtain.
Journal articles
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Preparation of regenerated cellulose from rice straw lignocellulosic waste and its use for reinforced paper products, TAPPI Journal July 2021
ABSTRACT: Rice straw waste is a lignocellulosic waste produced by farmers in large quantities. In this study, regenerated cellulose (RC) from rice straw was prepared by dissolving rice straw holocellulose (HC) in NaOH/Urea/Thio-urea/Water solution by the freeze-thawing process. The crystallinity index of RC was calculated at 31%, which is out of the crystallinity range of 39%•69% that has been previously suggested.The study indicated that the RC is amorphous with a low degree of polymerization (638) and higher hydroxyl group content as compared to HC. The fiber length of RC was found to be 26.7% shorter; however, the width of RC was 21.2% higher as compared to HC. Reduced kinked fiber content was observed in the fraction of RC (18.3%) as compared with HC (39.1%), and a higher curl index of fiber was observed more so in HC (10.5%) than RC (5.6%). Because of the regeneration process, the fiber length was reduced and a fines element content of about 96% was observed in RC compared to the initial fines content of HC (56.9%). Irrespective of the high fines element content of RC, the composite paper of rice straw bleached pulp and RC fibers was developed with an increase in the tensile index from 41.4 N.m/g to 71.2 N.m/g and an increase in the burst index from 4.7 kPa.m2/g to 5.3 kPa.m2/g with the addition of 5% and 15% RC, respectively. However, enhanced tear index of paper was observed up to 5% and then it declined upon further addition of RC. The study revealed that regenerated cellulose can be used as a strength additive to overcome the shortcomings of low mechanical properties in paper products.
Journal articles
Magazine articles
How old are fibers in paper for recycling and what is their
How old are fibers in paper for recycling and what is their life expectancy? A contribution to the life cycle assessment of wood fiber-based products, TAPPI JOURNAL July 2017