scholarly journals Possibilities for Optimization of Industrial Alkaline Steeping of Wood-Based Cellulose Fibers

Molecules ◽  
2020 ◽  
Vol 25 (24) ◽  
pp. 5834
Author(s):  
Catharina Fechter ◽  
Harald Brelid ◽  
Steffen Fischer
Keyword(s):  
Process Optimization ◽  
Cellulose Fibers ◽  
Industrial Processes ◽  
Alkali Concentration ◽  
Cellulose Ii ◽  
Alkali Cellulose ◽  
Viscose Fibers ◽  
Pre Treatment ◽  
High Alkali ◽  
Adapted Process

Steeping of cellulosic materials in aqueous solution of NaOH is a common pre-treatment in several industrial processes for production of cellulose-based products, including viscose fibers. This study investigated whether the span of commonly applied process settings has the potential for process optimization regarding purity, yield, and degree of transformation to alkali cellulose. A hardwood kraft dissolving pulp was extracted with 17–20 wt% aq. NaOH at 40−50 °C. The regenerated residue of the pulp was characterized regarding its chemical composition, molecular structure, and cellulose conformation. Yield was shown to be favored primarily by low temperature and secondly by high alkali concentration. Purity of xylan developed inversely. Both purity of xylan and yield varied over the applied span of settings to an extent which makes case-adapted process optimization meaningful. Decreasing the steeping temperature by 2 °C increased xylan content in the residue with 0.13%-units over the whole span of applied alkali concentrations, while yield increased by 0.15%-units when extracting with 17 wt% aq. NaOH, and by 0.20%-units when extracting with 20 wt%. Moreover, the yield-favoring conditions resulted in a narrower molecular weight distribution. The degree of transformation via alkali cellulose to cellulose II, as determined with Raman spectroscopy, was found to be high at all extraction settings applied.

scholarly journals Pretreatment optimization process of cotton to overcome the limits of its dyeability with indigo carmine

2019 ◽  
Vol 25 (3) ◽  
pp. 277-288 ◽  
Author(s):  
Maha Abdelileh ◽  
Manel Ticha ◽  
Ibtissem Moussa ◽  
Nizar Meksi
Keyword(s):  
Indigo Carmine ◽  
Chemical Properties ◽  
Cellulose Fibers ◽  
Alkali Concentration ◽  
Process Conditions ◽  
Color Strength ◽  
Design And Optimization ◽  
Cellulosic Fibers ◽  
Untreated Cotton ◽  
Dyeing Parameters

Cationization of cotton is emerging as an effective approach that solves problems associated with dyeing cellulosic fibers, especially cotton, by using indigo carmine. Indeed, this dye has no affinity for cellulosic fibers. Also, it has low fastness to light and washing. In this research, cotton modification is carried out by using Sera Fast GMX cationic agent in order to improve the yield of the exhaustion dyeing process by indigo carmine. The physical and chemical properties of unmodified cellulose fibers, as well as cationic modified cellulose fibers, were compared and investigated by SEM, FTIR and thermogravimetric analysis (TGA). The effect of the cationization process conditions, namely cationizing agent concentration, temperature of cationization, time of cationization and alkali concentration on the performances of dyeing of cotton by indigo carmine were studied, then the results were assessed by measuring the color strength (K/S) and the dyeing bath exhaustion E(%). Finally, a Box-Behnken experimental plan was used for experimental design and optimization of the dyeing parameters. The dyeing results of the optimized process conditions illustrate that cationization improves the fabric dyeability compared to the untreated cotton and the different fastness properties.

scholarly journals Consequences in a softwood kraft pulp mill of initial high alkali concentration in the impregnation stage

2019 ◽  
Vol 34 (1) ◽  
pp. 28-35 ◽  
Author(s):  
Elisabet Brännvall ◽  
Ida Kulander
Keyword(s):  
Kraft Pulp ◽  
Pulp Mill ◽  
Alkali Concentration ◽  
Pulp Yield ◽  
Kraft Pulp Mill ◽  
White Liquor ◽  
High Initial Concentration ◽  
Softwood Kraft Pulp ◽  
High Alkali ◽  
Energy Balances

Abstract Impregnation with high initial concentration is fast and efficient, leading to a homogeneous delignification in the subsequent cook, resulting in improved screened pulp yield. To obtain high initial alkali concentration, the white liquor flow needs to be significantly increased. The moisture content of the wood chips and the alkali concentration of the white liquor limit the initial alkali concentration of the impregnation liquor that can be reached. It is therefore of interest to evaluate the possibility to implement high alkali impregnation (HAI) industrially and the consequences this would have on the mill system. The effect of HAI on mass and energy balances in a kraft pulp mill has been studied using mill model simulations. The sensitivity to disturbances in important parameters for process control has been compared to impregnation scenarios used industrially. It was shown that high initial alkali concentration can be achieved on industrial scale by increased white liquor flow. HAI has a positive effect on recovery flows and reduces the need for make-up chemicals. The HAI concept is less sensitive to variations in process parameters, such as chip moisture and white liquor concentration, thus diminishing the risk of alkali depletion in chip cores.

scholarly journals Plasma Activation as a Powerful Tool for Selective Modification of Cellulose Fibers towards Biomedical Applications

Plasma ◽  
2020 ◽  
Vol 3 (4) ◽  
pp. 196-203
Author(s):  
Olivia Mauger ◽  
Sophia Westphal ◽  
Stefanie Klöpzig ◽  
Anne Krüger-Genge ◽  
Werner Müller ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Bacterial Adhesion ◽  
Biomedical Applications ◽  
Cellulose Fibers ◽  
Plasma Technology ◽  
X Ray ◽  
Cellulose Modification ◽  
Plasma Activation ◽  
Low Pressure Plasma ◽  
Pre Treatment

Cellulosic substrates are known for their biocompatibility, non-cytotoxicity, hypoallergenicity and sterilizability. It is therefore desirable to have a bundle of methods to equip them with tailored properties such as affinity profiles for various applications. In the case of highly swelling materials such as cellulose sponges, “dry” functionalization using plasma activation is the method of choice. The purpose of the study was to adapt low-pressure plasma technology for targeted cellulose modification. Using plasma (pre-) treatment combined with gaseous reactants like O2, ethylene oxide or silane, three different cellulose modifications were obtained and characterized by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). Swelling measurements and bacterial adhesion tests revealed distinctive material properties compared to educt. The development of these non-aqueous methods demonstrated an effective procedural route towards modified cellulosic materials for usage in wound dressing, micro patterned assays or bacterial filtration.

Influence of hemicellulose content of Eucalyptus and Pinus fibers on the grinding process for obtaining cellulose micro/nanofibrils

Holzforschung ◽  
2019 ◽  
Vol 73 (11) ◽  
pp. 1035-1046 ◽  
Author(s):  
Matheus Cordazzo Dias ◽  
Maressa Carvalho Mendonça ◽  
Renato A.P. Damásio ◽  
Uasmim Lira Zidanes ◽  
Fábio Akira Mori ◽  
...  
Keyword(s):  
Energy Savings ◽  
Alkali Concentration ◽  
X Ray Diffraction ◽  
Cellulose I ◽  
Partial Removal ◽  
Hemicellulose Content ◽  
Hemicellulose Removal ◽  
Pre Treatment ◽  
Mechanical Fibrillation ◽  
Determining Factor

Abstract The objective of this study was to verify the effect of the hemicellulose content of commercial bleached pulps on the ease of mechanical fibrillation and on its energy consumption (EC). NaOH in concentrations of 5% with 2 h of reaction, and 10% with 1 and 2 h of reaction, was evaluated for the partial removal of hemicelluloses. Pulp fibrillation was influenced by hemicellulose removal, being less fibrillated when excessive removal occurred (in the range of 4–8.5%). Hemicellulose content in the range of 9–13% increased the water retention value (WRV) and led to nanofibrils with smaller diameter, while a stronger alkali concentration reduced the WRV. X-ray diffraction (XRD) showed that reaction time was a determining factor for the crystallinity of the samples and partial conversion of cellulose I to cellulose II in pretreatments with NaOH 10% (1 and 2 h), and was a factor that may also damage the fibrillation process. Pre-treatment with NaOH 5% for 2 h promoted energy savings for both pulps. This work demonstrated that hemicellulose content has a considerable influence on the mechanical fibrillation and is a key aspect of the balance between efficient fibrillation and the energy required for that.

scholarly journals Effects of Curing Method on Properties and Salt-Scaling Resistance of Concrete under Lab Testing

2021 ◽  
Author(s):  
Greg Richards ◽  
Medhat Shehata
Keyword(s):  
Fly Ash ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Alkali Concentration ◽  
Salt Scaling ◽  
High Calcium ◽  
Curing Methods ◽  
Curing Method ◽  
High Alkali ◽  
Scaling Resistance

This paper presents a study of the effect of curing on the salt-scaling resistance of concrete containing supplementary cementitious materials (SCMs) under lab conditions. Two curing methods were examined: moist curing and wrapping in a tight plastic sheet. Wrapping concrete slabs in plastic was adopted to represent curing methods that do not supply the concrete with additional water. The two curing methods produced different scaling results; however, the outcomes did not change in terms of meeting or failing the acceptance limit. Curing in plastic wraps produced higher carbonation depth prior to exposing the sample to the salt solution. This could have contributed, partly, to the higher scaling obtained in wrapped samples, other than the sample with 40% high-calcium fly ash. For this sample, there is evidence that curing using plastic wraps maintained high alkali concentration in the surface concrete, which could have enhanced the pozzolanic activity of the fly ash at the surface.

scholarly journals ЕКОЛОГІЧНО-БЕЗПЕЧНА ТЕХНОЛОГІЯ ОЗДОБЛЕННЯ ТЕКСТИЛЬНИХ МАТЕРІАЛІВ З ВИКОРИСТАННЯМ ЕКСТРАКТУ ЧАШОЛИСТОК ПОЛУНИЦІ

2020 ◽  
Vol 142 (1) ◽  
pp. 102-111
Author(s):  
В. П. Плаван ◽  
І. М. Ткаченко ◽  
І. О. Ляшок ◽  
В. І. Ступа
Keyword(s):  
Cellulose Fibers ◽  
Metal Salts ◽  
Color Fastness ◽  
Technological Parameters ◽  
Textile Materials ◽  
Dyeing Process ◽  
Safe Technology ◽  
Wool Textile ◽  
Wool Fibers ◽  
Pre Treatment

Development of ecologically safe technology of finishing the textile materials using strawberry sepals extract and determination of influence for a mordant with salts from various metals on coloring quality. The technological parameters of the dyeing process by strawberry sepals extract were determined for linen, cotton, viscose and wool textile materials using pre-treatment with or without metal salts of Cu2+, Zn2+, Ni2+, Fe3+, Al3+. The color characteristics of the samples were determined using Adobe Photoshop CS6 software to evaluate the color quality. The resistance of the dyeing the textile materials to physical and chemical influences were determined by standard methods for textile materials. Ecologically safe technology of finishing the cellulosic and wool textile materials using strawberry sepals extract has been developed. The dyeing of textile materials made from cellulose fibers made it possible to obtain coloration from light to dark brown. After dyeing, the brightest samples were found based on wool fibers. Depending on the type of mordant, the following colors were obtained: Cu2+ cation made it possible to obtain green-brown shades, Al3+, Zn2+, Ni2+ cations gave colors in the yellow-brown shades; Fe3+ cation gave colors in black and brown shades. In general, the color fastness to wet and dry crocking for textile materials after dyeing with strawberry sepals extract are maximum for all specimens pre-treated with ferric cations except cotton and linen materials. The stability of color to perspiration in cotton, linen, viscose and wool samples ranges from 4 to 5 points. Color fastness to washing for samples from cellulose fibers are preferably 4-5 points, and for woolen is 4 points. The scientific novelty of the work is to determine the basic regularities of the dyeing process after pre-treatment with salts of metals Cu2+, Zn2+, Ni2+, Fe3+, Al3+ using as a dye of the strawberries sepals extract, which is a waste of the food industry. The technological parameters of the dyeing process by strawberry sepals extract, for cotton, viscose and woolen textile materials using pretreatment with metal salts of Cu2+, Zn2+, Ni2+, Fe3+, Al3+ were developed.

Fast microwave syntheses of fly ash based porous geopolymers in the presence of high alkali concentration

2016 ◽  
Vol 42 (8) ◽  
pp. 9866-9874 ◽  
Author(s):  
Sujitra Onutai ◽  
Sirithan Jiemsirilers ◽  
Parjaree Thavorniti ◽  
Takaomi Kobayashi
Keyword(s):  
Fly Ash ◽  
Alkali Concentration ◽  
High Alkali

scholarly journals Influence of pulp characteristics on the properties of alkali cellulose

Cellulose ◽  
2020 ◽  
Vol 27 (12) ◽  
pp. 7227-7241 ◽  
Author(s):  
Catharina Fechter ◽  
Steffen Fischer ◽  
Felix Reimann ◽  
Harald Brelid ◽  
Thomas Heinze
Keyword(s):  
Maximum Yield ◽  
Industrial Applications ◽  
Aqueous Alkali ◽  
Major Influence ◽  
Alkali Concentration ◽  
High Concentration ◽  
Alkali Extraction ◽  
Alkali Cellulose ◽  
Cellulose Material ◽  
Extraction Behavior

Abstract Alkali extraction of cellulose material is a common treatment for several industrial processes—especially the viscose process, which produces fibers for textile applications. This study investigated different generic dissolving wood pulps by means of alkali extraction (10–18 wt% aq. NaOH at 20–50 °C). The regenerated residue of the pulps was characterized for its chemical composition, molecular structure, and cellulose conformation. The investigated pulps had in common that glucan was most intensely extracted at low temperature and low concentration of aqueous alkali, xylan was most intensely extracted at high temperature and high concentration of aqueous alkali, and mannan was most intensely extracted at a concentration of aqueous alkali > 14 wtwt% at all temperatures applied. The degree of transformation via alkali cellulose to cellulose II as determined with Raman spectroscopy was found to be maximized for all pulps at high alkali concentration and temperature had no major influence. Maximum yield for all investigated pulps was found when extraction was done with 18 wt% aq. NaOH. The importance of temperature differed for the investigated pulps. The reason for the differences in extraction behavior or different absolute levels of resulting properties was found to be related to differences in the homogeneity and purity of the pulps. A conclusion of interest for industrial applications was that extracting the pulps with 18 wt% aq. NaOH led to an optimal alkalization result for yield, purity, and conversion. The steeping temperature chosen was found to be important to balance the yield and the purity of xylan-containing pulps. Graphic abstract

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