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0A STUDY OF THE EFFECT OF VARIOUS PARAMETERS ON OBTAINING CELLULOSE FROM THE FIBROUS WASTE OF COTTON CLEANING PLANTS (FWCCP) THROUGH ALKALI COOKING IN A COMPLEX PROCESS
1Rakhmonov J., 2Bozorov O.
1,2University of Economics and Pedagogy, Karshi, Uzbekistan https://doi.org/10.5281/zenodo.13994938
Abstract. Current technologies for producing cellulose from cotton lint fail to provide cellulose of sufficient quality for chemical processing, particularly in line with modern environmental requirements. Despite the widespread use of sodium hydroxide in the cooking process, the nature and environmental impact of harmful volatile compounds released during this stage remain poorly understood. This knowledge gap highlights the importance of conducting comprehensive research and development to design eco-friendly processes capable of producing high-quality cellulose from cotton waste, ensuring both industrial efficiency and environmental sustainability in chemical processing applications.
Keywords: temperature, cellulose, component, macromolecules, cooking, homogeneous, purification, reaction, cooking, autoclave, structural, complex.
INTRODUCTION
A comprehensive study was conducted on the process of obtaining cellulose from the fibrous waste of cotton cleaning plants (FWCCP) by investigating the effects of various parameters, including determining the grades of cellulose samples obtained from FWCCP based on the cooking process under specified parameters. Additionally, the physicochemical and mechanical-structural properties of the cellulose raw material obtained from the complex processing of FWCCP were studied [1].
The exploitation of underground resources, such as precious ores, rare metals, various types of bentonites, and the extraction of oil and gas, has become a key economic strategy for both developed and developing countries. Scientific research in these fields is being conducted at a high level [2].
Efficient and rational use of the aforementioned underground reserves, along with the incorporation of mathematical modeling of various factors during the exploitation process, is considered a crucial strategy for achieving high economic efficiency. In particular, one of the most important tasks for the oil and gas industry today is significantly improving the technology for obtaining stabilizing reagents, especially for developing new fractions of drilling fluids [3].
Research has been carried out on the process of obtaining cellulose, which serves as the primary stabilizing reagent for drilling fluid in the oil and gas industry. The process of obtaining cellulose from FWCCP under complex conditions and the influence of various parameters was studied [4].
EXPERIMENTAL PART
An analysis of the literature indicates that cellulose intended for chemical processing must be characterized by high frequency, molecular uniformity, a certain degree of polymerization, and high reactivity in etherification reactions. The stringent requirements for cellulose intended for
chemical processing are related to the properties of the final product, as noted in literature reviews, and are significantly influenced by both processing conditions and the quality of the cellulose. Therefore, before processing, the content of ash elements, fatty wax substances, lignin, pentosans, and other natural by-products of cellulose must be reduced to a minimum, while preserving the original amorphous structure [5].
Current technologies for producing cellulose from lint do not allow for obtaining high-quality cellulose suitable for chemical processing while meeting modern ecological requirements. For example, the question of which harmful volatile substances are released during sodium hydroxide pulping and how they may impact the environment has not been thoroughly studied. Therefore, research and development efforts aimed at creating environmentally friendly processes for obtaining high-quality cellulose from cotton industry waste for chemical processing are highly relevant [6].
RESULT AND DISCUSSION
The fibrous waste from cotton cleaning plants is used as a raw material according to GOST 3818.1-72 (Grade A, Type B) for obtaining cellulose suitable for chemical processing. We studied the possibility of obtaining high-quality cotton pulp from the fibrous waste of cotton cleaning plants through alkaline cooking. As highlighted in the literature review, one of the promising directions is addressing numerous ecological issues by implementing environmentally safe cellulose production technologies during cotton fibre pulping. Before alkaline cooking, the material was mechanically cleaned based on the method indicated in the tape.
The original tape showed the following impurity content in percentage terms: contamination -3.9%; ash content - 1.7%; lignin content - 4.31%; fat and wax content - 1.03%; pentosans - 2.61%. The fiber maturity was 84.4%, with a 6-8 mm length. Experiments to obtain high-quality cotton cellulose under laboratory conditions were conducted in a five-litre autoclave equipped with a stirrer.
Table 1. The concentration of sodium hydroxide and its effect on the quality indicators of
cellulose obtained from the fibrous waste of cotton cleaning plants (FWCCP)
Cooking conditions s —-i « c3 eö £ E -M e
Concentration, NaOH,% Pressure, MPa • E 13 <+H -c 0 <5 C 03 .2 S -M a > 1 £ £ S o o Fiber yield % Lignin yield % Whiteness, % C (U -M C o o (L> M O 3 o ö Pollution degre Wax oil content, Ash content, %
0.78 0.9 4.98 90.8 0.19 81 93.0 1570 0.59 0.18
0.9 0.9 4.99 89.6 0.18 87 94.7 1498 0.50 0.19
1.8 0.9 7.93 89.2 0.18 92 95.2 1401 0.42 0.16
0.9 1.4 3.96 87.4 0.20 73 97.8 1998 0.57 0.17
1.8 0.6 6.97 84.9 0.18 79 98.3 1198 0.38 0.21
The effects of alkali concentration, pressure, cooking duration, and temperature on the quality indicators of the obtained pulp were studied. Table 1 presents the results of experiments on alkali cooking of the material at varying sodium hydroxide concentrations and pressures.
As seen from the data in Table 1, during cooking, the content of lignin, fatty waxes, and mineral substances decreases, while the amount of alpha-cellulose increases, and its whiteness improves. As a result, the cellulose yield increases significantly. With the increase in alkali concentration, the lignin content sharply decreases. Initially, the alpha-cellulose content increases with rising alkali concentration, but after reaching a peak, it begins to decrease. An increase in alkali concentration also leads to an increase in cellulose yield, which subsequently results in a decrease in the degree of polymerization.
To determine the effect of processing temperature on the quality indicators of cellulose, a series of experiments was conducted. Table 2 presents data on the effect of cooking temperature on the quality of the resulting pulp. From Table 2, it can be seen that as the temperature increases from 95°C to 150°C, the whiteness of the cellulose significantly increases, but at the same time, the degree of polymerization and the amount of alpha-cellulose decrease. The influence of temperature on the balance between competing processes during low-pressure cooking-such as the removal and dissolution of non-cellulosic components-becomes more pronounced. This is likely related to the relative change in pressure with a uniform increase in temperature.
Table 2. Effect of alkaline cooking temperature on cotton cellulose content at mass concentration of 8%, sodium hydroxide concentration of 2.0%, cooking duration of 2.5 hours
Cooking
conditions PH w
Temperature X Pressure, MPa Cellulose yield % Lignin content, % Whiteness, % a cellulose content % C oi ''S N •G e S il 13 CP <+H o e e !-H g e Q Wax oil content,% Ash content, %
94 0.9 89.0 0.29 73 97.6 1799 0.49 0.11
129 0.9 86.7 0.14 89 98.4 1598 0.36 0.14
148 0.9 90.4 0.11 98 99.1 1210 0.40 0.16
129 0.4 86.6 0.23 88 96.3 1598 0.60 0.19
149 0.4 84.8 0.10 86 97.2 902 0.31 0.16
Table 3. The effect of alkaline cooking duration on the quality indicators of cellulose obtained
from the fibrous waste of cotton cleaning plants (FWCCP) was studied, with a mass concentration of 8%, sodium hydroxide concentration of 2.0%, and a temperature of 130°C.
Cooking conditions -M m (
Temperature X Pressure, MPa Cooking duration, min. Cellulose yield ( Lignin content, % Whiteness, % C (U -M C o o (L> t« O 3 13 o Ö Degree of polymerization, (! Wax oil content, Ash content, %
0,73 1,9 89 87,2 0,29 73 96,4 2199 0,39 0,16
0,9 1,9 119 86,1 0,19 84 98,2 1598 0,18 0,18
1,9 1,9 148 87,5 0,13 86 97,2 1394 0,15 0,15
0,9 0,4 119 89,3 0,59 69 99,6 1697 0,47 0,21
1,9 0,4 148 85,2 0,48 68 97,5 1594 0,49 0,19
Table 3 presents data showing the effect of cooking time on pulp quality. As indicated by the table, increasing the cooking time, on one hand, improves brightness, and on the other hand, ensures the gradual intensification of the removal process.
Experiments were conducted at various partial pressures (ranging from 0.4 to 1.2 MPa) to determine the effect of pressure on the quality indicators of cellulose.
Thus, the studies showed that the brightness and chemical purity of cellulose obtained from fibrous waste of cotton cleaning plants (FWCCP) increased due to the saponification and oxidation of mixtures containing fats, waxes, and lignin. The best results with lint were achieved at a temperature of 130°C, a mass concentration of 8%, 2% sodium hydroxide, a pressure of 1.0 MPa, and a cooking duration of 2.5 hours.
Hydrogen peroxide was used as a bleaching agent, which has a number of advantages over other bleaching agents, particularly the absence of environmental pollution, ease of use, and relatively low loss of cellulose during the bleaching process.
Sodium silicate was used as a stabilizer for peroxide bleaching, with its content varying depending on the amount of hydrogen peroxide obtained. It was experimentally determined that when hydrogen peroxide consumption ranged from 1.5% to 2.0% by weight of the raw material, sodium silicate consumption amounted to 2.0% and 2.5%, respectively. In all experiments, the pulp mass concentration was 8%, the temperature was 70°C, hydrogen peroxide consumption was 2.0% and 2.5%, and the bleaching duration was 60 and 90 minutes, respectively.
Extending the bleaching time beyond these values leads to a decrease in the brightness of the cellulose. The quality indicators of cotton pulp obtained under the above conditions - cooking followed by bleaching with hydrogen peroxide - were as follows: Brightness: 93%, Cellulose content: 99.3%, Fatty and waxy substances content: 0.041%, Ash content: 0.039%.
CONCLUSION
The investigation into the influence of various parameters of the alkaline cooking process on the quality characteristics of cellulose derived from cotton fibers has revealed significant insights. The study demonstrated that optimizing these parameters is crucial for enhancing the efficiency of cellulose production, particularly from low-grade cotton fibers. It was found that the ideal conditions for the alkaline cooking process include a lint concentration of 8.0%, a caustic soda concentration of 2.0% by weight, a pressure of 1.0 MPa, and a process duration of 120 minutes at a temperature of 130°C. These conditions not only ensure effective delignification but also enhance the purity and brightness of the resulting cellulose, making the process suitable for industrial applications.
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