Paper production from the waste of medicinal plants

. In this article the possibility of using licorice root waste as a fibrous raw material in the pulp and paper industry is investigated. It is shown it is possible to add up to 25% of bleached cellulose from licorice root waste to the paper composition for the production of writing paper.


Introduction
Environmental, economic and social aspects of industrial sectors become the defining directions of their development and correspond to the basic principles of the Western European countries of the modern world.This is caused by climate warming, depletion of natural resources, rising prices for energy, raw materials and finished products, increased environmental requirements, and a reduction in skilled labour.This is especially true for the paper industry, which is a major consumer of raw materials and energy resources [1].In the field of pulp and paper and printing industries, there is a problem of obtaining paper of the required quality, creating new types of paper for various purposes.Increased requirements have been established for the conduct of the technological process of paper production, namely, for the main raw material usedcellulose.It is known that the quality of printed products depends on the optical properties of printed paper: whiteness, gloss (gloss), transparency, ink perception.World paper production is expected to reach 416 million tons in 2022 [2].In this regard, the issue of developing technologies for the rational use of secondary fibre resources and the creation of new sources of raw materials based on natural resources.It is known that the use of waste and secondary material resources can significantly reduce the cost of raw materials, load idle production facilities, and create additional jobs.The use of recycled fiber obtained as a result of the processing of production waste, reduces the consumption of bleached and unbleached pulp from wood of various species, which is important from an economic and environmental point of view [3].
Currently, in the context of an acute shortage of fibrous raw materials in the paper industry, the recycling and reuse of fibrous waste from various industries is of great economic importance.In this aspect, pharmaceutical production waste, in particular licorice root meal is of particular interest.
The main advantages of licorice root are its annual reproducibility, the possibility of processing by any cooking methods, and low cost.Distinctive features of this non-wood raw material are a high content of hemicelluloses, ash content.There are known methods for pulping pulp from annual plants, including non-wood raw materials, which, being ecologically low-risk, make it possible to obtain technical cellulose with a high yield at relatively low energy costs and the absence of sulfur-containing emissions and effluents [4,5].As a rule, non-wood vegetable raw materials are processed by traditional alkaline methods in order to obtain fibrous semi-finished products [6,7].
The object of the study is licorice cellulose obtained from licorice root processing waste.The subject of the study is writing and printing paper obtained on the basis of various composite compositions.Licorice pulp was obtained by the soda method [8], according to the following technological sequence: cooking for 60 minutes, modulus 1:10, NaOH concentration -40 g / l, surfactant-0.5g / l, Na2 SO3-5 g / l [9].
Preparation of paper pulp.In the manufacture of paper in laboratory conditions, the grinding of fibrous semi-finished products was carried out in a laboratory roll.Semifinished products are pre-soaked for swelling in distilled water.A sample with a moisture content of at least 12% is subjected to swelling for 30 minutes, with lower moisture content -for one hour.Fibrous materials weighing 40 g pre-soaked in water are ground in a roll with a capacity of 4 liters.Every 8-10 minutes measure the degree of grinding and the average length of the fiber.The degree of grinding of the studied semi-finished products is adjusted to a value of 27-30 о ShR.

Methods
Making paper samples.Laboratory samples of paper from pre-prepared paper pulp are produced on a sheet-moulding machine LA-3.
Ash content of cellulose is determined according to GOST 7629-93, ISO 2144-87.Determination of paper tear resistance was carried out according to GOST ISO1924-1-96.the degree of sizing was determined by the Cobb method (GOST 12605-97 ISO 535-91).The smoothness of the paper was determined (GOST 12795-89).Determination of the transfer of ink to the printed material was carried out on a proofing machine IGT C1-C7 designed for making impressions in the form of printed strips by offset printing and determining the transfer of ink to the printed material, g/m 2 .

Results and discussion
The technological sequence of cooking pulp from licorice root processing waste is as follows: cooking with the active agent NaOH with a concentration of 40 g / l at a temperature of 140 0 C → washing with hot water → bleaching NaOCl with a concentration of 1-6 g/l → washing with cold distilled water → neutralization with sulfuric acid → drying When choosing a fibrous material, one should take into account its paper-forming properties, which together determine the achievement of the required quality of the manufactured paper.The properties of paper that define it as a printable material are primarily determined by factors such as the composition of the paper in terms of fiber, the content of chemicals, fillers, auxiliary substances in the composition, as well as the structure of the paper sheet.Usually, the predominant part of the range of paper for printing refers to mass paper products and is produced mainly from common fibrous semi-finished products: pulp from softwood and hardwood, wood pulp and waste paper.
The present work considers several composite compositions with the introduction of bleached licorice pulp and waste paper into the composition.Writing paper is intended for the manufacture of white paper products, school and general notebooks, paper in consumer sizes, letter paper and letterhead products.Depending on the composition of the fiber and quality indicators, paper can be produced in several grades.Regardless of the type of printing used, the printing properties of paper are influenced by its uniformity, ink acceptance, whiteness, opacity, surface smoothness and flatness, gloss, surface microgeometry, softness, resistance to dusting and plucking from the surface.In this work, only those specific printing properties of paper were considered, which determine the interaction of printing ink with paper and the high quality of the resulting prints during the printing process.
Printing properties largely depend on the composition of the paper.The introduction of licorice pulp into the composition helps to reduce the transparency of the paper and increase the porosity, as well as to obtain paper with a more uniform gap.But at the same time, the whiteness of the paper, its smoothness, gloss and the main indicators of mechanical strength are reduced.Mineral filler particles contribute to the formation of numerous small pores, due to the capillary properties of which the absorbing capacity of the paper for ink increases during To estimate the effective area of contact between the form and paper and the resolution of the surface, the index of surface smoothness of the obtained samples, which characterizes the microstructure of paper, was studied.In this work, the Beck method was used to determine the effective smoothness of paper samples.
The Table 1 shows the smoothness of the obtained samples using licorice pulp and waste paper brand MC-1.According to the data presented in Table 1, it can be seen that paper from recycled raw materials has the best smoothness index, and the introduction of licorice root into the composition of cellulose reduces the smoothness index in all three compositions.
Samples containing 25% licorice pulp and 75% cotton pulp have the best smoothness index, these indicators meet the requirements of the standard for non-calendered types of paper.Also, samples that contain 25% licorice pulp in composition with waste paper and sulfate wood pulp also meet the requirements of the standard.A further increase in the content of cellulose obtained from licorice root processing waste leads to a decrease in the smoothness index, which does not comply with state standards.
According to the standard that applies to printing, offset and coated paper, the main printing properties include: ink acceptance, print uniformity, translucence-penetration of the image on the reverse side of the print, ink fixing speed, resistance of the paper surface to plucking.There is a close relationship between ink film thickness and ink density.As the thickness of the ink layer increases, the reflectivity decreases and the optical density increases.On the obtained samples, the study of optical density was carried out using a VIPPen 450 densitometer, the results are shown in Table .2. After analyzing the data obtained, paper samples made from 100% recycled fibers have the best ink absorption, the thickness of the ink layer is approximately 1.5 microns.When licorice cellulose is introduced into the composition in composition with waste paper and cotton cellulose, the optical density of the resulting prints decreases, and the thickness of the ink layer also decreases.Samples obtained from wood pulp have the lowest optical density equal to 1.81%, while the thickness of the paint layer is approximately 1 micron.
The amount of ink transferred to the paper during printing, the depth of its penetration into the paper and the evenness of the distribution over the area of the applied image (text, pattern, printed surface) determines the quality of the print.The introduction of licorice pulp into the composition of paper changes the surface structure of the paper, changing the ability of paper to interact with paint (Fig. 1).
-Licorice cellulose + cotton cellulose -Licorice pulp + wood pulp -Licorice pulp + Waste paper MС-1 The highest indicator of ink transfer has a sample in the composition of which 75% licorice cellulose: 25% wood cellulose, as a result of the formation of a macro porous structure.The ink transfer index for a sample containing 75% cotton pulp: 25% licorice pulp is 30% lower.With a decrease in the content of licorice cellulose in the composition of these samples, the ink transfer decreases by 10-15%.When using licorice pulp with waste paper, ink transfer increases with a decrease in the amount of licorice pulp in the composition by 5-12% every 25%.As a result of the fact that waste paper has a small particle size and occupies the space between the fibres of licorice pulp, thereby forming a finely porous structure

Conclusion
For the selected composition, printing properties were studied.Samples based on waste paper with the addition of up to 25% of cellulose obtained from licorice root processing waste to the composition, with the introduction of kaolin as afiller and when used for sizing in the mass of rosin glue have the best indicators of smoothness, ink perception and optical density of the print.

Fig. 1 .
Fig. 1.Dependence of ink transfer of paper samples from the amount of licorice cellulose in the composition.

Table 1 .
The dependence of paper smoothness on the composition.

Table 2 .
The dependence of the optical density of prints on the composition of the paper.