A PRODUCTION METHOD OF CELLULOSE ACETATES FROM OLIVE POMACE

Technical Field

The invention relates to a method of producing fully biodegradable cellulose acetate from olive pomace, which is a by-product of the olive oil production process.

State of the Art

Olive pomace is known in the technical field as one of the waste materials left over from olive oil production. Generally, in the process of olive oil production, 40 units of olive pomace are obtained from 100 units of olives. Olive pomace is not a pure substance and contains a certain amount of oil. The mentioned oil content is approximately around 4-8%. In addition to oil, olive pomace contains about 25% moisture. The cellulose content of olive pomace is approximately around 40%. In this sense, the purification of olive pomace cellulose and obtaining products with industrial use from it is of great importance.

Brief Description of the Invention

The present invention relates to a method for producing cellulose acetates from pomace, meeting the requirements mentioned above, eliminating all disadvantages, and bringing additional advantages.

The main objective of the invention is to develop a method for serial production of cellulose acetate from pomace. In the method subject to the invention, first, pure cellulose is obtained from pomace, a renewable source, and then cellulose acetates are produced from the said pure cellulose. Thanks to the invention, it is possible to synthesize completely biodegradable cellulose acetates starting from pomace, a byproduct of olive oil production.

Another object of the invention is to synthesize cellulose acetates, which are degradable and environmentally friendly thermoplastic materials. These materials are thermoplastic polymers and can be used in place of many petroleum-based thermoplastic materials because they are biodegradable.

The structural and characteristic features of the invention and all its advantages will be clearly understood through the detailed description given below, and therefore the assessment should be made taking this detailed description into consideration.

Detailed Description of the Invention

In this detailed description, the preferred structures of the invention are explained for better understanding of the topic.

The invention relates to a method for producing completely biodegradable cellulose acetate from pomace, a by-product of the olive oil production process. In the said production method, firstly, the pomaces are dried, and the oils contained in them are removed by extraction. In the oil removal step, an oil-dissolving solvent is used. The oil- free pomace is then boiled with a sufficient amount of basic substance under pressure or at normal atmosphere to remove lignin, hemicellulose, and protein residues. As a result of this process, hemicellulose and lignin turn into water-soluble salts, and proteins break down into amino acids and pass into the aqueous solution. The structure of hemicellulose is given below: ucose -

- al ph a( 1 ,3) - Galactose

The remaining solid matter consists of pure cellulose. However, it may be colored because it contains a certain amount of lignin derivatives. This color is removed by boiling this raw cellulose with a suitable amount of hydrogen peroxide or sodium hypochlorite (bleach) as a bleaching agent, and pure cellulose is obtained.

If very pure pomace cellulose is desired, the obtained cellulose is regenerated by using carbon disulfide. The regenerated or bleached pomace cellulose is then reacted with an acetylation mixture containing acetic anhydride, methylene chloride, and sulfuric acid to perform acetylation. Monoacetate, diacetate, or triacetate can be obtained by adjusting the amount of acetic anhydride used and the holding times.

Pure cellulose is a carbohydrate polymer consisting of glucose units. A cellulose molecule can contain hundreds or thousands of glucose molecules. D-Glucose molecules are connected to each other by p-1 ,4 glycosidic bonds to form the cellulose polymer. The cellulose polymer has a linear chain structure and does not contain any branching (except for a few special solutions, such as Lucas reagent, Schweitzer reagent, LiCI/N,N-dimethylacetamide complex, etc.). The structure of cellulose is given below.

When the repeating units of cellulose are examined, it is seen that they contain primary and secondary hydroxyl groups. In a suitable environment, these hydroxyl groups easily undergo reactions such as esterification, etherification, substitution. One of the most common polymers based on cellulose is cellulose acetate. Thermoplastic polymers named cellulose monoacetate, cellulose diacetate, and cellulose triacetate are obtained depending on the degree of acetylation. Cellulose acetates are obtained by reacting cellulose with an appropriate amount of acetic anhydride (1 mole equivalent, 2 mole equivalents, 3 mole equivalents, etc., of glucose units). In the reaction, sulfuric acid and magnesium sulfate salt are used as catalysts. The obtained thermoplastic material is washed with water to remove sulfuric acid and magnesium salts. It is then used in the production of films, granules, or molded parts through a suitable process. The structure of cellulose diacetate is given below.

Here are examples of the process steps in the production method of cellulose acetates from olive pomace, according to the invention. These examples are provided as illustrative examples of the implementation and efficacy of the invention, without any limiting meaning.

Example 1: Extraction of Olive Pomace

5 kilograms of dry olive pomace and 15 liters of a low polarity solvent, preferably methylene chloride, ethyl acetate, acetone, or diethyl ether, referred to as oil solvent, are added to a 25-liter Soxhlet extractor. The pomace is siphoned at least twice and up to 30 times depending on its type. After the process, the oil-free pomace is used in subsequent stages.

Example 2: Obtaining Pure Cellulose from Olive Pomace

5 kg of oil-free dry olive pomace is placed into a 25-liter reactor, and 10 kg of a solution containing 2% to 50% (preferably 5%) base is added on top. The mixture is boiled optimally for 4 hours, ranging from 2 to 10 hours. If very pure cellulose is desired, the boiling process is carried out under pressure. In pressure boiling, the pomace is boiled in a pressure reactor at a temperature between at least 130 °C and a maximum of 180 °C. If the cellulose still carries some color after the boiling process, it is boiled with a 5% bleach solution. Then, the pomace cellulose is washed with water, pressed, and dried. The obtained pure cellulose is used in subsequent stages.

Example 3: Further Purification of Cellulose Obtained from Olive Pomace

5 kg of olive pomace cellulose obtained from Example 2 and 5 kg of 20% sodium hydroxide are placed into a 25-liter reactor. The mixture is stirred at room temperature or at a maximum temperature of 50 °C for 60 minutes. Then, the material is pressed and dried. Depending on the type of material, it is left to sit for at least 5 hours to a maximum of 3 days. Then, 10 kg of carbon disulfide is added to the material, and all the cellulose is stirred until dissolved. This process can take up to 5 days. The dissolved cellulose is then washed in a 15% sulfuric acid bath containing 10-20% sodium sulfate to regenerate it. As a result of this process, a very pure cellulose material known as Rayon is obtained. In subsequent steps, this material or the material obtained in Example 2 can be used.

Example 4: Production of Cellulose Diacetate from Olive Pomace Cellulose

5 kg of olive pomace cellulose, which has been previously treated with anhydrous acetic acid, is placed into a 50-liter reactor. The cellulose used here is left in 40 units of anhydrous acetic acid for 1 day per 100 units of cellulose, and then pressed and dried. Then, this cellulose is mixed with 15 kg of acetic anhydride, 50 g of sulfuric acid, and 20 kg of methylene chloride. The reaction mixture is vigorously stirred with a highspeed stirrer for 5-8 hours. During stirring, care is taken to ensure that the temperature is between 25-35 °C. Then, the reaction mixture is placed in a sufficient amount of 50% acetic acid solution and left to sit optimally for 72 hours, ranging from 48 to 96 hours. Sodium acetate is added in a sufficient amount to neutralize the sulfuric acid, and methylene chloride is removed by distillation. The washed mixture is dried. The obtained product is used as is without any further purification. The structure of the obtained product (cellulose diacetate) is given below.

Example 5: Production of Cellulose Triacetate from Olive Pomace Cellulose

5 kg of olive pomace cellulose, which has been previously treated with anhydrous acetic acid, is placed into a 50-liter reactor. The cellulose used here is left in 40 units of anhydrous acetic acid for 1 day per 100 units of cellulose, and then pressed and dried. Then, this cellulose is mixed with 15 kg of acetic anhydride, 50 g of sulfuric acid, and 20 kg of methylene chloride. The reaction mixture is vigorously stirred with a high- speed stirrer for 5-8 hours. During stirring, care is taken to ensure that the temperature is between 25-35 °C. Then, the reaction mixture is placed in a sufficient amount of 50% acetic acid solution and precipitated. The upper aqueous phase is discarded. Again, water is added and washed, during which a sufficient amount of sodium acetate is added to neutralize the sulfuric acid, and methylene chloride is removed by distillation.

The washed mixture is dried. The obtained product is used as is without any further purification. The structure of the obtained material (cellulose triacetate) is given below.