Technical Field of the Invention

The invention relates to a photocatalytic polymer composite material comprising rosemary, cherry laurel leaves, hemp seeds and St. John's Wort extract and a method for the preparation thereof. The polymer composite material obtained by the method of the invention is activated by using sunlight and the use of plants in polymer composite materials as renewable energy sources is provided.

State of the Art

Photocatalytic materials are nanotechnological and photochemical surface coating products that create a chemical reaction using light energy and can maintain their effectiveness for a long time when used once. These materials ensure the destruction of unwanted organics (dirt, microbes, bacteria, odours and harmful organic chemicals, etc.) in the air, water and on various surfaces. Photocatalysts used on exterior surfaces such as building walls, glass of solar panels and house windows protect the surfaces from ultraviolet (UV) rays by keeping more than 80% of the UV rays coming from the sun on the surface, thus prolonging the life of said exterior surfaces. Apart from all these, photocatalytic materials prevent the formation of water droplets and evaporation on glasses or mirrors, and also prevent bad odours that may occur on surfaces.

In the state of the art, photocatalytic materials are used in the dye degradation method. Dye degradation is a process in which large dye molecules are chemically broken down into smaller molecules. The resulting products are water, carbon dioxide and mineral by-products that give the original dye its colour, and the colour of the dye applied material becomes permanent as the dye decomposes. Photocatalytic materials used in the dye degradation method in the state of the art are nanomaterials obtained by green synthesis method or chemical synthesis method. Hazardous chemicals used in the synthesis process of nanomaterials obtained by the aforementioned chemical synthesis method pose a threat to human and environmental health. Nanomaterials obtained by using the green synthesis method are substances such as metallic silver, zinc oxide, and titanium oxide, and not only the raw material prices of these materials are high but these materials are also considered as toxic materials by the European Union. Titanium dioxide (TiC ) nanoparticles cause both single and double strand breakage in DNA, damage chromosomes and cause inflammation. It is already known that damage to DNA and chromosomes increases the risk of cancer. In a study on mice, nanoparticles (TiC ) were introduced into the drinking water of mice and genetic damage was observed within five days. When this five-day experiment is adapted to humans, it corresponds to a time of 1 .6 years. Once titanium dioxide enters the system (body), it begins to accumulate in different organs because the body cannot dispose of them. Since they are very small in size, they can pass from cell to cell, from organ to organ, and affect the mechanisms that take place in the cell [1], Looking at the information given above, it is known that ceramic and metal-based nanoparticles used as photocatalysts are harmful to human and environmental health.

Nanoparticles, which are the building blocks of nanomaterials, enter the human body through inhalation, nutrition and skin. Nanoparticles taken into the body easily pass into the blood. As a result of the nanoparticles passing into the blood, many organs in the human body are adversely affected. The target area affected by inhalation of nanoparticles is usually the lungs. Nanomaterials have also been proven to cause responses in the body against irritation, injury or infection. Today, with the developments in the field of nanotechnology, the usage rates of nanoparticles are increasing, which means an increase in the number of nanoparticles released into the ecological system day by day [2], In the 2021 Green Agreement Action Plan, it is emphasised that the European Commission will encourage practices and impose sanctions to ensure the use of biodegradable and plant-based plastics by 2030. This means that the development direction of the technology will change to enable the use of biodegradable and plant-based plastics.

In the state of the art, the work carried out by Seem Garg et al., relates to promoting plant leaf extracts for the synthesis of various nanostructures. In this study, the photocatalytic activity of bismuth oxychloride (BiOCI) is increased by using plant extracts [3], As can be clearly understood, BiOCI, which is an inorganic chemical compound, is needed to provide the material with photocatalytic properties. Bismuth and its salts can cause kidney damage; however, the degree of this damage is usually mild. Except, it can be fatal if taken in large doses. The ways bismuth can enter the body are through ingestion, inhalation, and skin. Bismuth and its salts enter the respiratory tract as an irritating dust causing respiratory tract irritation and cause problems with bad breath, metallic taste and gingivitis. When ingested, bismuth and its salts cause nausea, loss of appetite, weight loss, weakness, albuminuria, diarrhoea, skin reactions, stomatitis, headache, fever, insomnia, depression, rheumatic pain and black line problems on the gums due to sulphide accumulation. In addition, said bismuth and its salts cause irritation to the skin and eyes.

In another study by Ankush Chauhan et al., in the state of the art, the use of cannabis sativa leaf extract and silver-doped zinc oxide (Ag-ZnO) in photocatalytic dye degradation, as well as the antimicrobial activity of the said photocatalytic material, was investigated [4], As in the previous study, which we cited as a reference, in this study as well there is the use of a substance that harms the environment and human health in the supply of material with photocatalytic properties. In this study, said material is zinc oxide.

Although various studies are carried out on materials with photocatalytic properties, which are tried to be used in terms of superior physical properties such as showing antibacterial properties and extending material life in the state of the art, even in studies where said materials are obtained by using green synthesis instead of chemical synthesis, in addition to plant extracts, metals or inorganic materials that harm living and environmental health such as bismuth oxychloride (BiOCI) and silver-added zinc oxide (Ag-ZnO) are used. These materials not only harm the health of the living and the environmental, but also cause cost problems in terms of raw materials.

Due to the reasons such as limitations and inadequacies of the solutions in the state of the art, the use of metals or inorganic materials that harm the health of living and the environmental such as bismuth oxychloride (BiOCI) and silver-added zinc oxide (Ag-ZnO) in the production of photocatalytic materials, the use of which is tried to be widespread in the dye degradation method in the state of the art and in terms of superior physical properties such as showing antibacterial properties and containing a structure that extends the life of the material, and the fact that the mentioned materials harm the health of living and environmental as well as the cost problems in terms of the expensiveness of the raw materials used, it has been necessary to develop a polymer composite material with photocatalytic properties and the preparation method of this material, in which these problems are eliminated.

Brief Description and Aims of the Invention

In the invention, a photocatalytic polymer composite material comprising rosemary, cherry laurel leaves, hemp seeds and St. John's Wort extract and a method for the preparation thereof is explained. The polymer composite material obtained by the method of the invention is activated by using sunlight and the use of plants in polymer composite materials as renewable energy sources is provided. The photocatalytic effect of the polymer composite material with photocatalytic properties, which is the subject of the invention, continues as long as it is in contact with sunlight.

The aim of the invention is to provide a photocatalytic polymer composite material that enables the dye degradation process to be carried out using only plant extracts and sunlight without the need for any additional nanoparticle use such as zinc oxide. The provision of a polymer composite material with photocatalytic properties without the need for any additional nanoparticle use is also provided by the preparation method of a polymer composite material with photocatalytic properties, which is the subject of the invention. Said material contains rosemary, cherry laurel leaves, hemp seeds and St. John's Wort extract as plant extract. Said plant extracts gain photocatalytic properties to the polymer composite material of the invention by means of phosphorus (P), potassium (K), iron (Fe), magnesium (Mg) and calcium (Ca) minerals they contain. In addition, in the preparation method of the polymer composite material that is the subject of the invention, the plants are dried under sunlight while obtaining the plant extracts, and by this way the activity of the minerals in the plant extracts are increased, revealing the photocatalytic feature. In addition to all these, while obtaining the extracts, rosemary, cherry laurel leaves, hemp seeds and St. John's Wort plants are finely ground and boiled in a pure water content that does not contain any contamination. These processes enable the minerals in the plant extracts to emerge more intensely.

Another aim of the invention is to provide a polymer composite material with photocatalytic properties that makes an extra contribution to the ecological cycle. Contribution to the ecological cycle is provided by the use of hemp seeds in the production of a photocatalytic polymer composite material, which is the subject of the invention. According to statistics, hemp, a carbon-negative plant, absorbs 22 tons of carbon dioxide from the atmosphere during the harvest period with an acre of one hectare. With this feature, it reduces the amount of carbon footprint, which is a measure of the damage caused by human activities to the environment in terms of the amount of greenhouse gas produced, measured in unit carbon dioxide.

With the invention, a polymer composite material with photocatalytic properties is provided, which is low cost and contributes to the development of agricultural economy. A polymer composite material with photocatalytic properties, which contributes to the development of agricultural economy as well as low-cost, is provided by using rosemary, cherry laurel leaves, hemp seeds and St. John's Wort extracts instead of metallic silver in the preparation method of the said material, because high- cost raw materials such as oxide and titanium oxide. With the use of the said herbal ingredients in the production of a polymer composite material with photocatalytic properties, the cultivation of these plants will be expanded and the agricultural production of said plants will be increased.

Description of Drawings

Figure 1. Changes in absorbance as a result of LIV-VIS spectroscopy test of methylene blue solution by PVA film (BT) containing rosemary-cherry laurel extract

Figure 2. Absorbance changes as a result of LIV-VIS spectroscopy test of methylene blue solution by PVA film (KS) containing hemp seed-St. John's Wort extract

Figure 3. A polymer composite material with photocatalytic properties containing rosemary, cherry laurel leaves, hemp seeds and St. John's Wort extract.

Figure 4. Dye dissolution rates calculated as a function of time

Figure 5. SEM (scanning electron microscopy) image of hemp seed extract

Figure 6. EDS (energy dispersive spectrum) analysis of hemp seed extract

Figure 7. SEM image of St. John's Wort extract

Figure 8. EDS image of St. John's Wort extract

Figure 9. SEM image of rosemary extract Figure 10. EDS image of rosemary extract

Figure 11. SEM image of cherry laurel extract

Figure 12. EDS image of cherry laurel extract

Definition of Elements/Parts Composing the Invention

1. Polyvinyl alcohol (PVA) as polymer matrix material

2. Minerals of extracts of rosemary, cherry laurel leaves, hemp seeds and St. John's Wort plants

Detailed Description of the Invention

The invention relates to a photocatalytic polymer composite material comprising rosemary, cherry laurel leaves, hemp seeds and St. John's Wort extract and a method for the preparation thereof. The polymer composite material obtained by the method of the invention is activated by using sunlight and the use of plants in polymer composite materials as renewable energy sources is provided. A polymer composite material with photocatalytic properties, which is the subject of the invention, is produced without the use of any nanoparticles or nanomaterials.

A method for the preparation of a polymer composite material with photocatalytic properties, which is the subject of the invention, comprises the process steps of; i. drying of rosemary, cherry laurel leaves, hemp seeds and St. John's Wort plants under sunlight, ii. grinding the plants dried under sunlight to a size of 100-500 pm and then taking 20-40 grams of each dried plant and boiling it in 150-200 mL of distilled water at 85-100°C for 4-6 hours, iii. preparing a polyvinyl alcohol (PVA) solution as a result of dissolving 4-6 grams of PVA powder in 40-60 mL of distilled water by mixing at 90-100°C for 1 -1 ,5 hours, iv. adding the plant extracts obtained to the prepared PVA solution in 10-20 mL and mixing for 1 -1 ,5 hours at 90-100°C until a homogeneous mixture is obtained, and v. pouring the mixture containing plant extracts and PVA into moulds and drying it in an oven at 35-40°C for 24-36 hours and obtaining a polymer composite material with photocatalytic properties.

As can be understood from the process steps in the preparation method that is the subject of the invention, it is not possible to talk about the use of any additional nanoparticles while obtaining a polymer composite material with photocatalytic properties.

While preparing the plant extracts, 15-25% of the plant and polymer solution in the water are prepared and 10-15% of the polymer is added. 20-30% plant extract is used for the preparation of photocatalytic effective polymer nanocomposite material.

The photocatalytic property of the polymer composite material of the invention is activated only when exposed to sunlight. The extracts of rosemary, cherry laurel leaves, hemp seeds and St. John's Wort used in the invention gain photocatalytic properties to the polymer composite material of the invention, by means of the phosphorus (P), potassium (K), iron (Fe), magnesium (Mg) and calcium (Ca) minerals they contain. Increasing the density of said plant extracts also increases the photocatalytic effect. By means of the process step of drying the rosemary, cherry laurel leaves, hemp seeds and St. John's Wort plants, which are included in the preparation method of the photocatalytic polymer composite material subject to the invention, the activities of the minerals contained in the mentioned plants are also increased. By means of the process of grinding the plants dried in the sun at a size of 100-500 pm, it is ensured that the minerals are given to the water more intensely during the boiling of plants in pure water. The fact that water is 100% pure water has a very important place in obtaining the polymer composite material with photocatalytic properties that is the subject of the invention. Otherwise, contaminations such as harmful bacteria and microbes that may be present in the water damage the photocatalytic effect. The reason for this is that harmful bacteria or microbes cause the absorption of beneficial minerals that enable the photocatalytic feature to emerge. In addition, boiling the ground plants at 85°C in the method that is the subject of the invention also plays an important role in ensuring the photocatalytic effect. The reason for this is that temperatures above 85°C damage the minerals that provide the photocatalytic effect. The absorbance changes as a result of LIV-VIS spectroscopy test of methylene blue solution by PVA film (KS) containing hemp seed-St. John's Wort extract is shown in Figure 1 , whereas the absorbance changes as a result of LIV-VIS spectroscopy test of methylene blue solution by PVA film (KS) containing hemp seed-St. John's Wort extract is shown in Figure 2.

The expressions shown as MB-30, 60 and 90 are the waiting times of the polymer films in the dyed solution and are given in minutes. As a result of these times, LIV-VIS analyses were made, and absorbance values were measured. The resulting absorbance curves of the photocatalytic degradation experiments in the presence of nanocomposite PVA films of methylene blue (MB) dye are presented in Figures 1 and 2. As seen in Figures 1 and 2, plant extract-modified nanocomposite films absorb dye significantly during photocatalytic experiments. It was observed that methylene blue dye was degraded with plant extract modified nanocomposite films during natural light illumination. In the presence of KS and CT films, it was determined that approximately 18% and 22% of the MB dye were degraded during 90 minutes of light exposure. With a combination of adsorbed and degraded amounts (after 120 minutes), the total amount of MB dye removed from the system by KS and BT films was determined as 57.4% and 61.36%, respectively. In addition to the decrease in absorption intensity, the MB curves shifted towards the larger wavelength. The maximum value of the characteristic absorption peak of MB dye, which was exposed to light without any film sample added, was observed as 664 nm and this value did not change during the exposure time. In contrast, after exposing the MB dye to light in the presence of KS and BT nanocomposite films, the maximum point of the absorption peak of MBs shifted to 668.95 and 667.32 nm, respectively. The decrease of the absorbance peaks given in Figures 1 and 2 to lower values shows that the invention dissolves methylene blue from water, that is, it has a photocatalytic effect. The two peaks with the highest value in the figures (Fig. 1 and Fig. 2) are reference samples without extracts used for comparison with the invention. High peaks indicate that the sample does not dissolve dye. In other words, it can be seen from both figures (Figure 1 and Figure 2) that the absorbance peaks belonging to the invention with lower values prove that the invention has a photocatalytic effect.

In Figure 3, there is a general representation of the polymer composite material with photocatalytic properties that is the subject of the invention. The minerals (1 ) of rosemary, cherry laurel leaves, hemp seeds and St. John's wort extracts and polyvinyl alcohol (PVA) (2) as polymer matrix material are shown in Figure 3. The minerals (1 ) of the extracts of rosemary, cherry laurel leaves, hemp seeds and St. John's Wort plants are activated by sunlight, thus providing a photocatalytic effect. By means of the aforementioned photocatalytic effect, the dyes in the water are destroyed, and selfcleaning and also antibacterial surfaces are obtained.

Figure 4 shows the calculated dye dissolution rates as a function of time. The dye dissolution rate during the photocatalytic experiment was calculated using the equation below. Wherein Co and C are the dye concentrations before and after the reaction, respectively.

Dissolution rate (%) = [(Co-C)/Co]x1 OO

That is, Figure 4 is the graph showing the dissolution rates of the MV dye in solutions through time. As can be seen from the graph, the dye in the solutions begins to dissolve under natural light, and this rate increases gradually in BT and KS films.

Figure 5 shows the SEM image of the hemp seed extract. When the image given in Figure 5 is examined, nano-sized particles in the hemp extract are seen.

Figure 6 shows the EDS (energy dispersive spectrum) analysis of hemp seed extract. In Figure 6, the minerals found in hemp seeds are clearly visible. By means of the nanoparticles from these minerals, the photocatalytic effect is provided.

Figure 7 shows the SEM image of St. John's Wort extract. In Figure 7, nano- and microsized particles from St. John's Wort can be seen.

Figure 8 shows the EDS image of St. John's Wort extract. Figure 8 shows the minerals found in St. John's Wort. By means of the nano particles coming from these minerals, the photocatalytic effect is provided.

Figure 9 shows the SEM image of rosemary extract. Figure 9 shows the nano- and micro-sized particles from rosemary.

Figure 10 shows the EDS image of rosemary extract. By means of the nano particles coming from these minerals, the photocatalytic effect is provided.

Figure 11 shows the SEM image of the cherry laurel extract. In Figure 11 , nano- and micro-sized particles from cherry laurel can be seen. Figure 12 shows the EDS image of the cherry laurel extract. In Figure 12, the minerals found in cherry laurel are clearly visible. By means of the nanoparticles from these minerals, the photocatalytic effect is provided.

Figures 5 and 12 clearly show that plant extracts are present in nanoparticle films and contain the mentioned minerals such as Fe, Mn, K, P, Ca and Zn. Nanoparticles from minerals of elements such as Fe, K, P, Mn, Ca and Zn found in plant extracts act as photocatalysts. As can be seen from the SEM and EDS analyses, natural nanoparticles from the plant are clearly visible and elemental analysis reveals the types of these minerals.

According to the dye dissolution test of a photocatalytic polymer composite material comprising rosemary, chery laurel leaves, hemp seeds and St. John's Wort extract, it was observed that the plant based PVA nanocomposite dissolves the dye at a high rate. This effect is provided by the photocatalytic mechanism of action. The basic mechanism occurs when the material interacts with components such as dirt, dye and oil and dissolves or absorbs these substances. Materials with photocatalytic effect generally have properties such as hydrophobic, antibacterial, dirt/stain repellent, water purification and dissolving the dye in the dye water. In other words, the material subject to the invention has other properties besides dissolving dye in water.

The polymer composite material with photocatalytic properties, which is the subject of the invention, is used on exterior surfaces such as building walls, glass of solar panels and house windows. In addition to said outer surfaces, the material that is the subject of the invention can be impregnated with fabrics and gains self-cleaning and dirtrepellent properties to the fabric to which it is impregnated. In addition to all these, it is also used in areas such as water purification and filtration by using it in filter papers and membranes. In addition, the material that is the subject of the invention is added to dyes and used to provide dirt-proof walls inside and outside the house.

The polymer used in the polymer composite material of the invention is PVA, and the analyses show that the type of polymer used in the material that is the subject of the invention is important. Solutions of PVA aqueous solution and plant mixtures with PVA show acidic properties. In the acidic pH solution, the polymer surfaces are charged with positive charges as a result of the protonation of the nitrogen atom in the PVA block, and electrostatically interacts better with the anionic dyestuff, facilitating the dye adsorption, that is, the phototacalytic effect.

References

[1] Rethinking nano-tio2 safety: Overview of toxic ... - Wiley Online Library, (n.d.). Retrieved from https://onlinelibrary.wiley.com/doi/full/10.1002/smll.202002 019

[2] Tuylek, Z. (n.d.). Nanoteknolojinin Qevre ve insan Sagligi Uzerindeki Riskleri. Kilis 7 Arahk Universitesi Fen Ve Muhendislik Dergisi.

[3] Garg S., Yadav, M., Chandra, A., Gahlawat, S., Ingole, P. P., Pap, Z., & Hernadi, K. (2018). Plant leaf extracts as photocatalytic activity tailoring agents for BiOCI towards environmental remediation. Ecotoxicology and Environmental Safety, 165, 357-366.

[4] Chauhan, A., Verma, R., Kumari, S., Sharma, A., Shandilya, P., Li, X., Batoo, K. M., Imran, A., Kulshrestha, S., & Kumar, R. (2020). Photocatalytic dye degradation and antimicrobial activities of pure and AG-doped zno using cannabis sativa leaf extract. Scientific Reports, 10( ). https://doi.org/10.1038/s41598-020-64419-0