PRODUCTION OF CELLULOSE PULP FROM AZOLLA FILICULOIDES (WATER FERN)

2- Field of the Invention

This invention is about the production of paper and paper pulp as well as cellulose and textile industry. In this invention, azolla plant is used for the production of cellulose pulp, which can be used in the production of paper, cardboard, napkins, and envelope in papermaking industry and production of different types of polymer, cellulose containers and products including biodegradable disposab le containers and different cellulosic layers and other products of textile industry.

3- Prior art of the invention

Cellulose has been a resource used by human being from ancient times when papyrus was used to produce paper and such use increased at present because of high demands to paper, textile and cellulose products. Trees are the main source of cellulose industry. However, this source is too expensive, and for paper production, significantly high mechanical energy is required to shred wood and high thermal energy to boil them. In addition, to the production of 1 tons of paper, it is required to cut 14 to 20 trees.

In the invention registered under No. WO 00/28141, a method has been introduced for producing cellulose fibers and increasing the mechanical strength and humidity characteristics of the end-products including fiber materials such as paper. For this purpose, lignin is used in the solution with secondary additives consisting of a broad scope of sugars and natural polymers.

In another invention registered under No. P19803764, biopolymer starch, bleaching chemicals, starch, polyvinyl alcohols or enzymes are used for the production of cellulose. The paper produced by this invention contains 5% lignin and other fibers such as thermo-mechanical pulps. Therefore, the fibers produced in these products are not pure.

In another invention registered under No. US Pat. No. 49267498, polymeric additives are added to the end-product.

In the invention registered under No. US Pat. No. 4756801, cationic starch is added during the process of paper production, and such starch causes that paper fibers to be filled with fillers and pulps. The invention registered under No. EP1080271 is exclusively about the application of polysaccharides including hydrophobic and aromatic groups for the production of paper. The invention registered under No. EP0148647 is about the process of papermaking by adding polymer for long fibers and adding starch exactly before forming the paper. The invention registered under No. W02004/046464 explains the process of cellulose products by adding starch and other secondary materials.

In recent decades, agricultural wastes such as rice straw and bagasse have been used to supply industrial cellulose. This method has not damages to the wood. However, as these materials are not sufficient to be used as an alternative of wood and it restricts the production capacity of a factory. Recently, the production of paper from stone has been introduced, and as it can be employed only for the production of paper, it cannot be used for all cellulose products. In addition, the cellulose papers cannot be replaced in general by stone papers.

4- Existing Problems

Cellulose pulps made of agricultural wastes cannot be an alternative for those made of trees. Materials used in paper production industry are mainly made of trees by producing cellulose fibers in papermaking, textile industry, and cellulose industry throughout the world. Therefore, damages arising out of cutting the trees and the earth remain. Cutting trees causes soil erosion and leads to natural disasters and increases air pollution, because trees act as the lungs of the earth. The increase in cutting trees leads to the global warming as well.

No one of the methods used up to the present time has been able to meet the full needs of the above-mentioned industries and prevent the cutting of trees. In addition, the methods introduced require the high consumption of energy and chemicals.

5- Purposes of Invention

This invention aims to solve the problem of cutting trees and damages arising out of it. In this invention, there is no need to cutting trees because of the fast cultivation and production of azolla (water fern), and it meet the present needs of the cellulose industry, some parts of textile industry, papermaking, and wherever cellulose is required. As a roughly renewable resource, it has a high and to some extent unlimited production capability in the factories. I n addition, because of its low price, short process of producing cellulose pulp made of azolla, cellulose-based products can be produced which are of low price and provide the producers with higher profits. Paper is of great importance in any country and used in any educational and research sectors as well as many organizations, health sector, and for packaging. The present resources used for paper production and other cellulose industries are supplied from cutting trees. For instance, around 14 to 20 trees must be cut to produce one tons of paper used for writing. This is not only cost consuming in economic terms but also regarded as a threat to the reduction of trees on the earth and causes damages to the natural resources of the countries and their environment. On the other hand, it increases air pollution leading to the increase in global warming. According to the international news, more than 5 million people die because of air pollution. By producing paper from wood, 300 or 400 thousand liters of water are used to produce one ton of paper. In addition, high mechanical and thermal energy is required in producing cellulose pulp extracted from trees. However, cultivating, irrigating, and cutting these trees are economically cost consuming for the government and industry owners. Each tree can form a small ecosystem, in or near which many organisms and animals live.

6- Description

The present invention is a process designed for producing cellulose pulps from Azolla filiculoides, which can be used in cellulose industry, papermaking, and textile industry. However, other species of azolla can be used too. Azolla is a plant growing in water and can be propagated very fast by high-quantity reproduction. Such reproduction is so high in quantity that a mass of this plant can be doubled only within several days. This algae-like plant, which is a species of fern, is one of the few plants of earth that can absorb nitrogen from the air and use it as food.

The method used in this invention for the production of cellulose pulp is so that wet azolla is put in the cooking vessel. Sodium hydroxide (caustic soda) equal to one eighth up to one fifth of the mass of wet azolla is added into the vessel. Thereafter, sodium sulfide equal to three seventh (3/7) of caustic soda is added as well. The content of the vessel is cooked for 30 minutes in the temperature of 96 °C using 90-°C water. The volume of water added to the above content should be enough for solvi ng the above chemical compounds. This volume may vary accordingly. However, water must be to the volume required for moisturizing azolla. The pressure required for cooking is 1 to 2 atm. At this time, when cooking is finished, cellulosic fibers of azolla are removed and the pulp undergoes washing process to recover alkalis (which will be carried out if this system exists in the factory).

In the bleaching phase, one tenth of the mass of removed fiber, which is cooked azolla pulp, caustic soda (NaoH) with one seventh up to three seventh of the mass of caustic soda (sodium hydroxide) is calculated and then, sodium sulfide (Na ₂ S) is added. Thereafter, 10 to 30 cc (ml) of bleach and other types of whitening substances will be added for 60 grams of azolla. To this content, 60-°C water is added and the azolla solution is put in the temperature of 60 to 75 °C for the duration of 10 to 15 minutes. The bleached pulp is then washed and is used in different cellulose industries, textile industry, and paper production. (If the thermal apparatus is of high capabilities and the thermal conductivity of the cooking vessel is appropriate, there will be no need to use water in such temperature, and water under the ambient temperature (25 °C) is enough. In fact, water in such temperature does not cause any change in the process.

This plant exists in different countries such as Iran, Philippines, Indonesia, North America, especially Canada, India, and in Europe, the UK in particular. It also exists in other regions of the world. In Iran, it can be found on the surface of Anzali Lagoon, and is regarded damaging to ecosystem, because, it covers the surface of water by its rapid reproduction preventing light and oxygen penetrate into the water. Therefore, the photosynthesis of the plants existing in the water reduces and the oxygen of water reduces gradually. On the one hand, such reduction in oxygen causes that the aquatics, such as fish, die, and on the other hand, reduction of oxygen increases the activities of the anaerobic organisms such as bacteria and changes the PH of water. This is another reason of the loss of important aquatics of the lagoon . As the removal of azolla has not been economically of importance up to the present time, this invention will justify such removal and can save Anzali Lagoon, which is considered as one of the most important international lagoons threatened by this plant causing the destruction of this lagoon.

This invention can use azolla for producing cellulose pulp used in the production of different types of paper, napkins, and cardboard as well as products of cellulose and textile industries. In addition, this invention helps to prevent cutting trees for the production of paper, and saves forests and their ecosystems. On the other hand, as the reproduction of azolla is so fast that it can be doubled only within several days, the production of cellulose products from azolla is economically cost saving and it can help global economy. Considering the problem of water shortage in most countries of the world, this invention uses less water and cellulose pulp made from azolla can be made in the temperature under 98 °C. Moreover, there is no need to mechanical energy for shredding this plant. By this invention, less energy is used for the production of cellulose products. Hence, the industrial production using this plant and this process is economically more cost saving, and cellulose products can be supplied to the markets in low prices. In this invention, there is no need to mechanical energy required for shredding cellulose resources, low thermal energy, and short time. In addition, low volume of chemicals used for the extraction of cellulose from this plant in comparison with those used for extraction of cellulose from trees. Depending on the method of production used in a cellulose plant, for example paper production factory, and based on the quality and type of papers, this pulp can be used in the production lines of factories with different additives and special process. This plant is a low-price resource and can be cultivated and harvested easily for the cellulose industries of the world. Regardless of its economic aspect, this invention is environmentally of importance. In fact, this invention can help cellulose industry like papermaking to produce their products without cutting trees and with considerably low costs.

The special characteristic of azolla is that it can be an appropriate alternative for other cellulose resources such as trees and other ones. Its reproduction is high and fast, and a mass of azolla can be doubled less than a week. This characteristic provides a cellulose factory having high potentials of production, machineries, and production lines, with the possibility to produce the same amount of cellulose products, which was produced within one year, only within several months. In fact, this plant is a low-price and easily accessible resource without any limitations and its production level depends only on the capabilities of production lines and machineries existing in the related factories.

This invention can be used for the supply of threat and fabric fibers and in general in textile industry as well as the production of different types of cellulose products such as papers, cardboards, napkins, biodegradable dishes and containers or any product in which azolla is used as the source of fibers and cellulose in cellulose and textile industries or any other types of industry, factory, or ma nufacturing plants.

Also, this cellulose dough derived from Azolla, can be used as an appropriate cellulose resource and suspension for producing nano cellulose.

By adding concentrated sulfuric acid to this dough in a very low proportion under heat and agitation, Nano Cellulose gel can be achieved. Of course, other compounds and hydrolysis techniques also can be used.

Furthermore, by adding some sodium hydroxide (NaOH) in the process, Hydroxyl groups (OH) can be replaced by some sulfate groups (HS03) that increases thermal resistance.

We can obtain gel production from acid hydrolysis by washing and then continuously centrifuges it more pure.

Therefore, in this process nano-crystalline cellulose known as NCC or CNC was produced. And also with a little change in the process of synthesizing a variety of nano-cellulose from azolla was achieved. In fact, for the first time in the world nano cellulose was made from azolla and in this unique process nanocry stalline cellulose has been synthesized for producing pulp. This produced nano -cellulose can be used in all projects in the world that uses nano-cellulose. This material is used in many industries in the world such as automotive industry, medical industry, dentistry and dental equipment, pharmacy, Aircraft, Shipbuilding, aerospace industries, textile industry, making clothes and vests and bulletproof glasses, cosmetics industry, also manufacture of advanced electronic components such as bendable screens, and so in printing and packaging industries, the building materials industry, manufacture of home appliance components, in making filters and membranes, making sponges, cleaning up oil spots, for retrieving oil reservoirs and in general, making all kinds of composites.

7- Invention Advantages

In this invention, there is no need to mechanical shredding. It uses low thermal energy in comparison to what is used in traditional methods of the factory.

Reduced need to water: in the process of producing paper from trees, approximately 300 to 400 thousand liters of water is used. In this invention, this volume is reduced to 5,000 to 50,000 liters of water. That is, a reduction of around 250,000 liters of water for the production of one ton of paper. If the production of paper uses this plant instead of trees, water is saved and this volume of water saving per year can supply potable water required for seven billion people during ten year.

Reduction of energy consumption during the production process of cellulose pulp in comparison with the energy used for the production of pulp from trees

During the process of cooking or kraft pulping using trees, it is required to use thermal energy up to 170 °C for several hours (usually 3 hours). In this invention, cellulose pulp needs only thermal energy up to 96 °C for about 20 to 30 min. Therefore, thermal energy is saved up to 85% during cooking process. Moreover, in the process of shredding trees, by which wood is converted to chips, a considerable mechanical energy is required. In this invention, there is no need to mechanical energy. In fact, this energy reduced 100%. In general, approximately 80 to 92% of energy consumption required for cellulose or paper pulping is reduced and this amount of energy reduction is of great significance, since this invention needs 10 to 20 % of energy for pulping. Therefore, the costs of cellulose or paper pulping reduce more than 60 to 75%, and this reduction can reach 80% depending on the location of the factory.