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TECHNICAL SCIENCE / «<g©yy©®UOUM=J0Umay» #10(169), 2023
TECHNICAL SCIENCE
UDC: 577.352.2
Lebedev Vladimir Vladimirovich,
Ph.D. in technical sciences, Assistant Professor, Assistant Professor of the department ofplastics
and biologically active polymers technology, National Technical University «Kharkiv Polytechnic Institute»
Miroshnichenko Denis Viktorovich,
Doctor of Technical Sciences, professor, chair of the department of oil, gas and solid fuel refining technologies
National Technical University «Kharkiv Polytechnic Institute»
Tykhomyrova Tetyana Sergiivna
Ph.D. in technical sciences, Assistant Professor, Assistant Professor of the department of Chemical Engineering and Environment Protection, National Technical University «Kharkiv Polytechnic Institute»
DOI: 10.24412/2520-6990-2023-10169-26-28 STUDY OF BROWN COAL HUMIC SUBSTANCES HYBRID MODIFICATION ON SORPTION RESISTANCE OF BIODEGRADABLE MATERIALS
Abstract.
Researching on brown coal humic substances hybrid modification of biodegradable materials based on pol-ylactide and coffee waste for their sorption resistance in different liquid mediums are carried out in this work. The objects of study were extrusion polylactide of the Terramac TP-4000 brand, coffee grounds waste with article size limit from 0.5 to 1 mm, dried to moisture content 0,5% and humic substances, which were obtained by extraction of brown coal. The obtained diffusion coefficient values of different liquids are in the range from 0,95 * 10-10 to 6,65 *10-10 m2\s allow us to conclude that the designed brown coal humic substances hybrid modified biodegradable materials based on polylactide and coffee waste can be used as a polymer base in terms of their sorption properties for one and multi-use tableware production.
Keywords: humic substances, brown coal, biodegradable, materials, polylactide, coffee waste, sorption resistance
Introduction
One of the topical areas in the Sustainable Development concept implementation is using biodegradable polymer materials [1, p. 2653] Today, the design of biodegradable polymer materials is being implemented in three main areas: the creation of plastics based on natural raw materials, the production of biodegradable polymers by biotechnology, and making conventional plastic biodegradable. In such biodegradable polymer materials the principle of «Zero waste» is implemented throughout the entire life cycle of the material - «production - use - disposal». So this polymer class is dynamically used in the market today. Over the past 15 years, the total production of biodegradable polymer materials has increased from 100 thousand tons in 2005 to 2.5 million tons in 2022 [2, p. 6310]. The most important field of their application is the production of polymer films, containers and packaging for food products, as well as the manufacture of single and reusable tableware and cutlery [3, p. 535]. Proceeding from the possibility of using biodegradable polymer materials in a wide range of applications, studies on the stability of their properties and characteristics under certain operating conditions are highly relevant [4, p. 1712]. Research on ways to create biodegradable polymer materials with a complex of high performance characteristics as well as the ability to biodegradation are urgent and require a complex approach.
From the above studies, it can be seen that the most important characteristics of biodegradable polymeric materials, in addition to their biodegradability, is their compliance with certain operating conditions in various applied areas [5, p. 118580]. For biodegradable
polymeric materials intended for the production of disposable and reusable tableware, resistance to various food environments, stability of the shape and size of products when both cold and hot foods and drinks are inside them is very important [6, p. 134841]. Earlier, in our work [7-10], we designed and investigated brown coal humic substances hybrid modified biodegradable materials based on polylactide and coffee waste, in which we had achieved high strength and technological characteristics. An important area of research for the designed brown coal humic substances hybrid modified biodegradable materials based on polylactide and coffee waste is the study of their resistance in contact with the most typical food liquids.
The aim of the research was to researching of brown coal humic substances hybrid modification of biodegradable materials based on polylactide and coffee waste for their sorption resistance in different liquid mediums.
Raw materials and test methods
The objects of study were:
- extrusion polylactide of the Terramac TP-4000 brand;
- coffee grounds waste with article size limit from 0.5 to 1 mm, dried to moisture content 0,5% ;
- humic substances, which were obtained by extraction of brown coal with alkaline solution of sodium pyrophosphate, followed by extraction with 1 % sodium hydroxide solution and precipitation with mineral acid.
Brown coal humic substances hybrid modified biodegradable materials based on polylactide and coffee waste were obtained by extruding pre-prepared raw
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materials in a single-screw laboratory extruder at a temperature of 170-200 ° C and a roll rotation speed of 30100 rpm. The L / D ratio of the extruder is 25, and in order to increase the uniformity of dispersed waste distribution in the finish compositions, 2 mass passes were used to obtain finished samples.
Accelerated determination method for diffusion coefficient was used [7, p. 168]. Samples of new environmentally friendly polymeric materials (parallelogram with sides size's 10x15x5 mm) were kept in operational food liquid mediums. It was made 20 parallel experiments for each composition in each chosen liquid
medium, measurements were made after 14 days in the liquid medium.
Results and discussion
We have selected 5 operating liquids for studying sorption characteristics - the most common and popular in different food places. There were tea, coffee, water, detergent and Coca-Cola. Based on experimental data according to the method described in [12], the diffusion coefficient for samples of brown coal humic substances hybrid modified biodegradable materials based on polylactide and coffee waste was calculated (Table 1).
Table 1
Diffusion coefficient (m2\s) in brown coal humic substances hybrid modified biodegradable materials _based on polylactide and coffee waste with different coffee grounds content*_
Composition Liquid medium
Water Coffee Tea Detergent Coca-Cola
PLA+0,5 HA % 0,95*10-10 1,73*10-10 2,02*10-10 1,55*10-10 2,15*10-10
PLA+0,5 HA % +CW40% 1,14 *10"10 2,46*10-10 3,27*10-1° 3,27*10-10 4,84*10-10
PLA+0,5 HA % +CW50% 2,77*10-10 3,35*10-10 4,01 *10-10 2,86*10-10 4,88*10-10
PLA+0,5 HA % +CW60% 3,14*10-10 3,81*10-10 4,65*10-10 3,14*10-10 6,65*10-10
* PLA - polylactide, HA - brown coal humic substances, CW - coffee waste
The data in table 1 indicate the hydrophobic nature of the surface of both the source polymer material polylactide +0,5 % brown coal humic substances and brown coal humic substances hybrid modification of biodegradable materials based on polylactide and coffee waste for their sorption resistance in different liquid mediums. At the same time, the diffusion coefficient increases in series: water < coffee < detergent <tea < Coca-Cola. As the content of coffee grounds increases, the diffusion coefficient also increases.
When new brown coal humic substances hybrid modified biodegradable materials based on polylactide and coffee waste the least contains of coffee grounds, the diffusion coefficients of all operational liquid me-
diums increase in the range 21,4-119,1%. In compositions, that contains 60% of filler (coffee grounds) the increase in diffusion coefficients of all operational liquid mediums was in the range of 85,4-240,5%. Thus, for brown coal humic substances hybrid modified biodegradable materials based on polylactide and coffee waste, the diffusion coefficients for the studied media were in the range 1,14-6,65 *10-10 m2\s. For composition with coffee grounds, an increase in diffusion coefficients in PLA compositions is actually due exclusively to the hydrophilicity of the filler surface.
The maximum size stability of brown coal humic substances hybrid modified biodegradable materials based on polylactide and coffee waste was shown for water and coffee (Table 2).
Table 2
Size stability (A%) in samples of brown coal humic substances hybrid modified biodegradable materials _ based on polylactide and coffee waste with different coffee grounds content_
PLA+0,5HA% PLA+0,5 HA % +CW40% PLA+0,5HA%+CW50% PLA+0,5HA%+CW60%
Detergent 0,2 0,7 2,2 5,2
Tea 1,0 1,3 1,9 3,3
Coffee 0,3 03 0,7 3,9
Water 0,1 0,8 0,9 3,3
Coca-Cola 1,1 3,2 3,6 11,2
The highest size stability is characteristic of the polylactide +0,5 % humic substances. For it the change in the initial size after exposure in the test media was 0,2-1,1%. With an increase in the content of coffee grounds from 40 to 60% wt. there is increasing in the initial size of all compositions after exposure to the test media. Note, that the brown coal humic substances hybrid modified biodegradable materials based on pol-ylactide and coffee waste with 60% wt. coffee waste content have the lowest size stability after exposition in Coca-Cola and detergent: 11,2 and 3,6%, respectively. In general, brown coal humic substances hybrid modified biodegradable materials based on polylactide and
coffee waste with 50% content of coffee waste , show optimal size stability in all studied media.
Conclusion
The article conducts research on brown coal humic substances hybrid modification of biodegradable materials based on polylactide and coffee waste for their sorption resistance in different liquid mediums. The researching data indicate the hydrophobic nature of the surface of both the source polymer material polylactide +0,5 % brown coal humic substances and brown coal humic substances hybrid modification of biodegradable materials based on polylactide and coffee waste for their sorption resistance in different liquid mediums. At
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TECHNICAL SCIENCE / «ШЦУШШУМ-ЛШШаИ» 2023
the same time, the diffusion coefficient increases in series: water < coffee < detergent <tea < Coca-Cola. As the content of coffee grounds increases, the diffusion coefficient also increases for all brown coal humic substances hybrid modified biodegradable materials based on polylactide and coffee waste. The obtained diffusion coefficient values of different liquids are in the range from 0,95 * 10-10 to 6,65 *10-10 m2\s allow us to conclude that the designed brown coal humic substances hybrid modified biodegradable materials based on pol-ylactide and coffee waste can be used as a polymer base in terms of their sorption properties for one and multi-use tableware production.
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