| 1. |
- Norlin, Börje, associate professor, 1967-, et al.
(author)
-
Sulfur homogeneity mapping in 2D and 3D can improve packaging paper strength
- 2023
-
Conference paper (other academic/artistic)abstract
- Sodium sulfite is commonly used for impregnating wood chips prior to refining when producing high-yield pulps such as CTMP. The impregnation process should ideally result in evenly sulfonated lignin, i.e. similar concentrations of sulfite (SO3 ^2-) ions in all parts of each wood chip. Sulfonated lignin is known to swell the fiber wall, which is beneficial for developing higher joint strength between fibers. In reality, even sulfonation is not easy to achieve considering variations in wood chip size, density, quality, etc. Being able to trace where the sulfite ions end up in the wood or fiber structure can therefore be key to both process and product development in the future. Synchrotron measurements can provide an understanding of the sulfur distribution both inside single wood fibers and on a larger scale between wood fibers. There is little knowledge of wood fiber nanostructures in 3 dimensions, although some interesting research has been conducted recently [1]. We have compared these measurements with 2D synchrotron XRF mappings [2]. The 3D material mapping provides insight into a sub-fiber level, but the 2D mapping technique might be preferable when studying sulfur distributions due to the highly uneven sulfur content observed. We can probably learn more about the development of fiber-joint-strength and strength uniformity in products by characterizing the distribution of sulfur on the sub-fiber level. This paper discusses feasible future measurement strategies.[1] Fernando, D., et.al, Sci Rep 13, 2350 (2023). DOI: 101038/s41598-023-29113-x[2] Norlin, B., et.al, JINST 18 C01012. DOI: 10.1088/1748-0221/18/01/C01012
|
|
| 2. |
- Norlin, Börje, associate professor, 1967-, et al.
(author)
-
Visualisation of sulphur on single fibre level for pulping industry
- 2023
-
In: Journal of Instrumentation. - : Institute of Physics (IOP). - 1748-0221. ; 18:01, s. C01012-C01012
-
Journal article (peer-reviewed)abstract
- In the pulp and paper industry, about 5 Mt/y chemithermomechanical pulp (CTMP) are produced globally from softwood chips for production of carton board grades. For tailor making CTMP for this purpose, wood chips are impregnated with aqueous sodium sulphite for sulphonation of the wood lignin. When lignin is sulphonated, the defibration of wood into pulp becomes more selective, resulting in enhanced pulp properties. On a microscopic fibre scale, however, one could strongly assume that the sulphonation of the wood structure is very uneven due to its macroscale size of wood chips. If this is the case and the sulphonation could be done significantly more evenly, the CTMP process could be more efficient and produce pulp even better suited for carton boards. Therefore, the present study aimed to develop a technique based on X-ray fluorescence microscopy imaging (µXRF) for quantifying the sulphur distribution on CTMP wood fibres. Firstly, the feasibility of µXRF imaging for sulphur homogeneity measurements in wood fibres needs investigation. Therefore, clarification of which spatial and spectral resolution that allows visualization of sulphur impregnation into single wood fibres is needed. Measurements of single fibre imaging were carried out at the Argonne National Laboratory’s Advanced Photon Source (APS) synchrotron facility. With a synchrotron beam using one micrometre scanning step, images of elemental mapping are acquired from CTMP samples diluted with non-sulphonated pulp under specified conditions. Since the measurements show significant differences between sulphonated and non-sulphonated fibres, and a significant peak concentration in the shell of the sulphonated fibres, the proposed technique is found to be feasible. The required spatial resolution of the µXRF imaging for an on-site CTMP sulphur homogeneity measurement setup is about 15 µm, and the homogeneity measured along the fibre shells is suggested to be used as the CTMP sulphonation measurement parameter.
|
|
| 3. |
|
|
| 4. |
- Rahman, Hafizur, Researcher, 1978-, et al.
(author)
-
Improved CTMP impregnation by the use of X-ray fluorescence measurements
- 2023
-
Conference paper (other academic/artistic)abstract
- Defibration of wood chips in high-yield pulping such as CTMP production involves sulfonation of wood chips using (Na2SO3). When aiming to improve product properties, one key issue to investigate is the evenness of the sulfonation, i.e., the distribution of the sulfite (SO32-) ions. The challenge is that the inner parts of the wood chips absorb much less sodium sulfite than the outer parts. As a result, less sulfonated wood fibers have different bonding properties. It is likely that the efficiency and evenness of fiber separation in a chip refiner depend greatly on how evenly the chips have been sulfonated. Uneven sulfonation then results in higher shives (unseparated fibers) content which impairs product properties. We suggest a laboratory-scale miniaturized X-ray fluorescence (XRF) scanner for measuring sulfur distribution in the wood chips on-site. By minimizing the differences in sulphonate content between fibers, we can minimize the requirement for sulfite (SO32-) dosage to a certain degree of fiber separation, thereby reducing the total amount of electricity used in chip refining. There has been a significant improvement in commercial XRF microscopy scanners over the last few years, but the spatial resolutions achieved are insufficient. We have developed an XRF scanner optimized for sulfur fluorescence energies [1], and further continued this development by implementing frontier technology polycapillary X-ray optics. We present spatial resolution measurements and discuss the relevance and usability of the proposed measurement methodology to demonstrate its performance.[1] Rahman, H., et.al, ACS Omega 2022, 7, 51, 48555–48563, DOI: 10.1021/acsomega.2c07086
|
|
| 5. |
- Rahman, Hafizur, Researcher, 1978-, et al.
(author)
-
On-Site X-ray Fluorescence Spectrometry Measurement Strategy for Assessing the Sulfonation to Improve Chemimechanical Pulping Processes
- 2022
-
In: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 7:51, s. 48555-48563
-
Journal article (peer-reviewed)abstract
- Minimizing the fiber property distribution would have the potential to improve the pulp properties and the process efficiency of chemimechanical pulp. To achieve this, it is essential to improve the level of knowledge of how evenly distributed the sulfonate concentration is between the individual chemimechanical pulp fibers. Due to the variation in quality between pulpwood and sawmill chips, as well as the on-chip screening method, it is difficult to develop an impregnation system that ensures the even distribution of sodium sulfite (Na2SO3) impregnation liquid. It is, therefore, crucial to measure the distribution of sulfonate groups within wood chips and fibers on a microscale. Typically, the degree of unevenness, i.e., the amount of fiber sulfonation and softening prior to defibration, is unknown on a microlevel due to excessively robust or complex processing methods. The degree of sulfonation at the fiber level can be determined by measuring the distribution of elemental sulfur and counterions of sulfonate groups, such as sodium or calcium. A miniaturized energy-dispersive X-ray fluorescence (ED-XRF) method has been developed to address this issue, enabling the analysis of sulfur distributions. It is effective enough to be applied to industrial laboratories for further development, i.e., improved image resolution and measurement time.
|
|
| 6. |
- An, Siwen, et al.
(author)
-
Geometrical influence on Hg determination in wet sediment using K-shell fluorescence analysis
- 2023
-
In: X-Ray Spectrometry. - : John Wiley and Sons Ltd. - 0049-8246 .- 1097-4539. ; 52:4, s. 82-196
-
Journal article (peer-reviewed)abstract
- To quickly identify maritime sites polluted by heavy metal contaminants, reductions in the size of instrumentation have made it possible to bring an X-ray fluorescence (XRF) analyzer into the field and in direct contact with various samples. The choice of source-sample-detector geometry plays an important role in minimizing the Compton scattering noise and achieving a better signal-to-noise ratio (SNR) in XRF measurement conditions, especially for analysis of wet sediments. This paper presents the influence of geometrical factors on a prototype, designed for in situ XRF analysis of mercury (Hg) in wet sediments using a 57Co excitation source and an X-ray spectrometer. The unique XRF penetrometer prototype has been constructed and tested for maritime wet sediment. The influence on detection efficiency and SNR of various geometrical arrangements have been investigated using the combination of Monte Carlo simulations and laboratory experiments. Instrument calibration was performed for Hg analysis by means of prepared wet sediments with the XRF prototype. The presented results show that it is possible to detect Hg by K-shell emission, thus enabling XRF analysis for underwater sediments. Consequently, the XRF prototype has the potential to be applied as an environmental screening tool for analysis of polluted sediments with relatively high concentrations (e.g., >2880 ppm for Hg), which would benefit in situ monitoring of maritime pollution caused by heavy metals. © 2022 The Authors
|
|
| 7. |
- Rezasson, Reza, 1985-, et al.
(author)
-
A fast and non-destructive alternative to the burnout method for paperboard quality inspections using phase-contrast X-ray imaging
- 2023
-
In: TAPPI Journal. - : TAPPI. - 0734-1415. ; 22:2, s. 99-106
-
Journal article (peer-reviewed)abstract
- An X-ray based quality inspection method for paperboard was implemented and tested as a fastand non-destructive alternative to the burnout method. An argument against X-ray imaging for inspection of paperand paperboard has been that X-ray absorption is low in paper. To overcome this limitation, we used phase-contrastX-ray imaging (PCXI), which gives higher contrast than conventional attenuation-based imaging for low-absorbingmaterials such as paper. The suggested PCXI method was applied to previously prepared and quality rated samplesusing the burnout method.A strong similarity between the burnout images and the PCXI images was observed. In conclusion, further devel-opment of the phase-contrast X-ray method would provide an interesting option for replacing or complementing thestandard burnout method.
|
|
