PROCESS FOR BLEACHING AND DEODORIZING ALGAE OR ALGAE EXTRACTS

Abstract

PROCESS FOR BLEACHING AND DEODORIZING ALGAE OR ALGAE EXTRACTS The present invention relates to a process for bleaching and deodorizing algae or algae extracts, for use in the manufacture of plastics or composites.The process according to the invention comprises the following steps: (a) a step of obtaining algae or algae extracts, (b) a step of preparing a bleaching and deodorizing solution comprising hydrogen peroxide and water, (c) a step of soaking the algae or algae extracts in said bleaching and deodorizing solution for at least 2 hours, either under exposure to natural or artificial light or without exposure to natural or artificial light, (d) a step of separating the algae or algae extracts, still wet, from the bleaching solution, (e) a drying step during which the algae or algae extracts, still wet, are subjected to a temperature between 40 and 80°C.(f) optionally, if step (c) of soaking took place without exposure to natural or artificial light, a step of exposure to UV-C before or during step (e) of drying, (g) a step of recovery of algae or algae extracts, bleached, deodorized and dried.

Description

Title of the invention: PROCESS FOR BLEACHING AND DEODORIZING ALGAE OR ALGAE EXTRACTS

[0001] The present invention relates to a process for bleaching and deodorizing algae, or algae extracts. More specifically, the invention relates to a process for bleaching and deodorizing algae, or algae extracts, for use in the manufacture of plastics or composites.

[0002] The increased demand for plastics imposed by modern society results in annual production levels reaching millions of tons. The production of plastic products relies on a limited stock of fossil raw materials (oil and gas), which constitute more than 90% of its raw material. Plastic is one of the most polluting and dangerous materials for the environment, humans and animals. For example, of the 8.3 billion tons of plastics manufactured between 1950 and 2015, 6.3 billion tons became waste, of which approximately 79% accumulated in landfills or in nature. In addition, the manufacture of plastic is itself a source of pollution because it generates polluting by-products.

[0003] If today, imagining a world without plastic is almost impossible, a reasoned reflection on production methods is necessary to limit the impact of plastics on our environment.

[0004] Thus, given the awareness of consumers and manufacturers, research has been directed for several years towards the use of plant-based materials, renewable and ideally biodegradable, to replace fossil raw materials in the manufacture of plastic. Such a plastic is then called "bio-sourced". A large majority of bio-sourced plastics are made from plant materials from wheat, corn, beetroot, sugar cane or potato. While this alternative offers more environmentally friendly plastics, it has the disadvantage of diverting part of the plant production initially intended for food consumption.

[0005] Thus, more recently, algae have been the subject of studies and research as raw materials or sources of raw materials in the manufacture of plastics. Indeed, algae synthesize a large quantity of compounds, in particular polysaccharides, which have interesting functional properties for the manufacture of plastic products and which can be extracted for this purpose. Examples include ulvans, agar, alginates, as well as lactic acid. In addition, the plastic products thus manufactured are biodegradable and compostable. Elsewhere, the use of algae in the manufacture of plastic responds to another environmental problem: the proliferation of algae on the coasts and its danger.

[0006] Green algae, for example, are present in the sea in their natural state, but their rapid proliferation is linked to environmental disturbances, such as soil pollution by nitrates and phosphates, global warming, etc. This imbalance represents a danger for humans and ecosystems. The excessive growth of algae can be the source of episodic or chronic phenomena of anoxia in the environment and suffocation and then death of many species. When stranded in large quantities and not collected, their decomposition is encouraged and causes the emission and accumulation of greenhouse gases, but also of hydrogen sulfide, a toxic gas that can be fatal in high concentrations. If not collected and not recovered, they represent a danger for humans and the environment.

[0007] Giving a value to this waste helps to reduce the environmental impact associated with seaweed strandings.

[0008] The use of algae or algae extracts in the manufacture of plastics thus makes it possible to respond to a double problem: on the one hand, the increase in demand for plastic by limiting the use of petroleum-sourced materials and plant materials which compete with agricultural land and on the other, the pollution of algae which is dangerous for humans and the environment if it is not treated.

[0009] The manufacture of plastic materials from algae is for example described in international application WO 2017 / 046356.

[0010] However, although algae or algae extracts are perfectly suited to the production of plastics and finished plastic products with mechanical properties at least identical to those of standard plastics, a drawback remains due to the color and odor characteristics that they induce. However, manufacturers are waiting for finished products with little or no color and without the characteristic odor of algae.

[0011] The aim of the present invention is to propose a simple, effective and environmentally friendly process for the bleaching and deodorization of algae or algae extracts, in particular with a view to their use in the manufacture of plastic or composite materials for the production of colorless and odorless finished products.

[0012] To this end, the invention relates to a process for bleaching and deodorizing algae or algae extracts, comprising the following steps:

[0013] a. a step of obtaining algae or algae extracts, b. a step of preparing a bleaching and deodorizing solution comprising hydrogen peroxide and water, c. a step of soaking the algae or algae extracts in said bleaching and deodorizing solution, for at least 2 hours either under exposure to natural or artificial light or without exposure to natural or artificial light, d. a step of separating the algae or algae extracts, still wet, from the bleaching solution, e. a drying stage during which the algae or algae extracts, still wet, are subjected to a temperature between 40 and 80°C. f. optionally, if the soaking step (c) was carried out without exposure to natural or artificial light, a UV-C exposure step before or during the drying step (e), g. a step of recovering algae or algae extracts, bleached, deodorized and dried.

[0014] In the context of the method according to the invention, it is the combined action of hydrogen peroxide and light or heating at a certain temperature range which allows the bleaching and deodorization of algae or algae extracts. By way of comparison, the action of hydrogen peroxide alone does not allow such a result to be obtained satisfactorily. This combined action can be implemented either in a single step, by soaking in hydrogen peroxide under light exposure, or in two separate steps including a step of soaking in hydrogen peroxide and a subsequent step of exposure to UV-C or heating at a certain temperature range.

[0015] Thus, in more detail, the method according to a first alternative comprises the following steps:

[0016] (a) a step of obtaining algae or algae extracts,

[0017] (b) a step of preparing a bleaching and deodorizing solution comprising hydrogen peroxide and water,

[0018] (c) a step of soaking the algae or algae extracts in said solution of bleaching and deodorization, under natural or artificial light, for at least 2 hours,

[0019] (d) a step of separating the algae or algae extracts, still wet, and the bleaching solution,

[0020] (e) a drying step during which the algae or algae extracts, still humid, are subjected to a temperature between 40 and 80°C.

[0021] (g) a step of recovering bleached, deodorized algae or algae extracts and dried.

[0022] The method according to a second alternative comprises the following steps:

[0023] (a) a step of obtaining algae or algae extracts,

[0024] (b) a step of preparing a bleaching and deodorizing solution comprising hydrogen peroxide and water,

[0025] (c) a step of soaking the algae, or algae extracts, in said solution of bleaching and deodorizing, for at least 2 hours,

[0026] (d) a step of separating the algae or algae extracts, still wet, and the bleaching solution,

[0027] (e) a drying step during which the algae, or algae extracts, still humid, are subjected to a temperature between 40 and 80°C.

[0028] (f) optionally a step during which the algae or algae extracts, still wet, are subjected to UV-C exposure before or during drying step (e),

[0029] (g) a step of recovering bleached, deodorized algae or algae extracts and dried.

[0030] The progress of the bleaching can be monitored visually using a color chart or by spectrometry. Thus, at the end of the process according to the invention, whatever the alternatives, the algae or algae extracts are suitable for use in the manufacture of colorless, bleached and odorless plastics or composites. The process can be carried out using all species of algae, filamentary or in the form of leaves, green, brown or red algae, etc., on whole or crushed, fresh or dry algae, or on algae extracts.

[0031] Furthermore, since hydrogen peroxide is non-persistent and decomposes rapidly into oxygen, the effluents recovered after contact with the matrix can be sent to a lagoon area without specific treatment before recycling or discharge into nature. The process according to the invention is therefore perfectly environmentally friendly.

[0032] In the context of the invention, the term "algal extract" means any compound, or mixture of compounds, obtained after the implementation of any extraction process known to those skilled in the art. These will in particular be extracts of polysaccharides or fibers. Polysaccharides and fibers derived from algae are known and their algal origin is identifiable.

[0033] “Natural light” also means all the different forms of light emitted by the sun or the moon.

[0034] “Artificial light” also means all the different forms of light produced artificially and diffused by a lamp or any other artificial light source.

[0035] "Bleaching" also means the loss of the natural color of the material, by neutralization, elimination or destruction of the compounds responsible for the color, especially pigments. The term "bleaching" can be used alternatively.

[0036] "Deodorization" also means the loss of the natural odor of the material, by neutralization, elimination or destruction of the compounds responsible for the odor.

[0037] According to a characteristic of the invention, during step (b), the bleaching and deodorizing solution is prepared with sea water, fresh water or brackish water.

[0038] According to a preferred embodiment, the bleaching and deodorizing solution is prepared with sea water.

[0039] Indeed, unexpectedly, the combined action of hydrogen peroxide and sea water makes it possible to obtain bleaching and deodorization more quickly and more effectively.

[0040] Preferably, the bleaching solution is prepared at a volume concentration of 0.01 to 20% of hydrogen peroxide.

[0041] Preferably again, step (b) of preparing a bleaching and deodorizing solution comprises adjusting the pH of said solution to a value between 7 and 11.5, more preferably 7.

[0042] The pH of fresh or sea water around 7 is suitable, but a modification of the pH between 11 and 11.5, for example by adding sodium hydroxide, can be considered.

[0043] According to one embodiment, the method comprises the addition, during step (b), of at least one compound chosen from iron sulfate, alkali metal silicate, an alkaline earth metal, a complexing agent for alkaline earth metal ions, or one of their mixtures in the bleaching and deodorizing solution.

[0044] The addition of such components makes it possible to accelerate the speed of the bleaching and deodorizing reactions by promoting the oxidation of hydrogen peroxide. However, such additions remain completely optional.

[0045] Advantageously, the step (c) of soaking the algae or algae extracts in the bleaching and deodorizing solution takes place for at least 8 hours, preferably at least 12 hours, more preferably at least 24 hours.

[0046] It is understood that depending on the quantity of material to be bleached, a person skilled in the art will easily be able to determine the soaking time necessary to obtain bleaching and deodorization.

[0047] Soaking is carried out continuously or discontinuously by intimately mixing the bleaching and deodorizing solution with the algae or algae extracts. Intimate mixing can be carried out in outdoor algae culture tanks such as 5m3, 65m3 and 150m3 raceways or in controlled agitated tanks.

[0048] According to a preferred embodiment of the invention, the soaking step (c) takes place under light exposure, more precisely under natural daylight outdoors, under artificial light produced by LEDs, or under artificial light combining LED and UV-C.

[0049] The LEDs, light emitting diodes, or electroluminescent diodes preferably used are those which emit wavelengths between 400 nm and 700 nm.

[0050] Advantageously, the soaking step (c) takes place under heating at a temperature between 70 and 95°C.

[0051] Heating during the soaking step, with exposure to light, further accelerates the bleaching and deodorizing reactions. When the soaking step takes place without light exposure, heating may be necessary in the case of low hydrogen peroxide concentration.

[0052] Advantageously, the soaking step (c) takes place according to a ratio of 20 to 60 g of algae or algae extracts, per liter of bleaching and deodorizing solution.

[0053] Preferably, the soaking step (c) takes place under mechanical stirring without bubbling.

[0054] Agitation plays a role in the kinetics and promotes discoloration and deodorization. It must be carried out by mechanical agitation without bubbling, bubbling being a hindrance to bleaching.

[0055] According to one embodiment, the soaking step (c) takes place at a temperature between 70 and 95°C, preferably both under natural or artificial light and at a temperature between 70 and 95°C.

[0056] Preferably, the separation step (d) consists of filtration.

[0057] Preferably, step (e) of exposure to a temperature between 40 and 80°C is carried out in a controlled oven.

[0058] According to one embodiment, the method comprises a step of contacting the algae or algae extracts with ozone, before or during the soaking step.

[0059] The invention also relates to bleached and deodorized algae or algae extracts, obtained or capable of being obtained by a process as described above.

[0060] The invention also relates to a plastic or composite material comprising bleached and deodorized algae or algae extracts, obtained or capable of being obtained by a process as described above.

[0061] The invention also relates to a method for manufacturing finished plastic or composite products comprising a method as described above.

[0062] The invention finally relates to a finished plastic or composite product comprising algae or algae extracts, bleached and deodorized, obtained or capable of being obtained by a process as described above.

[0063] A finished plastic or composite product here means any object manufactured from plastic or composite materials, such as a container, a bag, a film, etc.

[0064] The characteristics of the invention mentioned above, as well as others, will appear more clearly on reading the following description of exemplary embodiments which illustrate the invention in a non-limiting manner. Example 1

[0065] In a 1 L beaker, mix 498 mL of seawater and 2 mL of 35% active oxygen hydrogen peroxide to obtain a bleaching and deodorizing solution. Then add 10 g of fresh Ulva Rigida seaweed, stir magnetically, without bubbling, and place an LED strip around the beaker.

[0066] Bleaching, measured using a color chart, and deodorization of the algae are observed in less than 24 hours.

[0067] The algae are then filtered. Example 2

[0068] In a so-called "raceway" basin with a capacity of 5m3, fill with sea water then add 0.5% v / v of hydrogen peroxide 35% active oxygen so as to obtain a bleaching and deodorizing solution. Then add Ulva Rigida type algae so as to obtain an algae concentration of 20 kg fresh (20% DM) / m3 of bleaching and deodorizing solution. Expose, with mechanical stirring (paddle wheel type), outside under natural light, in the middle of summer, for a maximum of 5 days.

[0069] Bleaching measured using a color chart and deodorization of the algae are observed in less than 5 days.

[0070] Once bleaching and deodorization are achieved, the algae are harvested on a curved grid then drained, dried and crushed. Example 3

[0071] In a 1 L beaker, add 498 mL of seawater then 2 mL of hydrogen peroxide with 35% active oxygen to obtain a bleaching and deodorizing solution. Add 10 g of fresh Ulva Rigida type algae, stir magnetically and place the beaker on a hot plate set to 70°C. Wait 24 hours, remove the algae, wring them out and then spread them out in an oven at 60°C for 24 hours.

Claims

Claims

1. A method for bleaching and deodorizing algae or algae extracts, comprising the following steps: (a) a step of obtaining algae or algae extracts, (b) a step of preparing a bleaching and deodorizing solution comprising hydrogen peroxide and water, (c) a step of soaking the algae or algae extracts in said bleaching and deodorizing solution for at least 2 hours, either under exposure to natural or artificial light or without exposure to natural or artificial light, (d) a step of separating the algae or algae extracts, while still wet, from the bleaching solution, (e) a drying step during which the algae or algae extracts, while still wet, are subjected to a temperature of between 40 and 80°C.(f) optionally, if step (c) of soaking took place without exposure to natural or artificial light, a step of exposure to UV-C before or during step (e) of drying, (g) a step of recovery of algae or algae extracts, bleached, deodorized and dried.

2. A method according to claim 1, characterized in that the bleaching solution is prepared at a volume concentration of 0.01 to 20% hydrogen peroxide.

3. Method according to claim 1 or 2, characterized in that the bleaching and deodorizing solution is prepared with fresh water, sea water or brackish water, preferably sea water.

4. Method according to one of the preceding claims, characterized in that step (b) of preparing a bleaching and deodorizing solution comprises adjusting the pH of said solution to a value between 7 and 11.5, more preferably 7.

5. Method according to one of the preceding claims, characterized in that it comprises the addition, during the preparation of the bleaching and deodorizing solution and into the latter, of at least one compound chosen from iron sulfate, alkali metal silicate, an alkaline earth metal, a complexing agent for alkaline earth ions, or one of their mixtures.

6. Method according to one of the preceding claims, characterized in that that said step (c) of soaking the algae or algae extracts in said bleaching and deodorizing solution takes place for at least 8 hours, preferably at least 12 hours, more preferably at least 24 hours.

7. Method according to one of the preceding claims, characterized in that the soaking step (c) takes place under natural or artificial light, said light being chosen from natural daylight outdoors, under artificial light produced by LEDs, or under artificial light combining LED and UV-C.

8. Method according to one of the preceding claims, characterized in that the soaking step (c) takes place in a ratio of 20 to 60 g of algae or algae extracts, per liter of bleaching and deodorizing solution.

9. Method according to one of the preceding claims, characterized in that the soaking step (c) takes place under mechanical stirring without bubbling.

10. Method according to one of the preceding claims, characterized in that the soaking step (c) takes place at a temperature between 70 and 95°C, preferably both under natural or artificial light and at a temperature between 70 and 95°C.

11. Method according to one of the preceding claims, characterized in that the separation step (d) consists of filtration.

12. Method according to one of the preceding claims, characterized in that step (e) of exposure to a temperature between 40 and 80°C is carried out in a controlled oven.

13. Method according to one of the preceding claims, characterized in that it comprises a step of contacting the algae or algae extracts with ozone, before or during step (c) of soaking.

14. Bleached and deodorized algae or algae extracts obtained or obtainable by a process according to one of claims 1 to 1

15. d lu. Plastic or composite materials comprising algae or algae extracts, bleached and deodorized, obtained or capable of being obtained by a process according to one of claims 1 to 13.

16. A method of manufacturing finished plastic or composite products comprising a method according to one of claims 1 to 13.

17. Finished or composite product comprising algae or algae extracts, obtained or capable of being obtained by a process according to one of the claims 1 to 13.