Magnetic nanocomposite, its production process and use.

Description

1 / 22 Magnetic nanocomposite, its production process and use. FIELD OF APPLICATION

[001] The present invention applies to the area of ​​biotechnology and water treatment, being intended for obtaining a magnetic nanocomposite based on the direct functionalization of carbon nanotubes (CNTs) or allotropes thereof, with magnetic nanoparticles of biological origin (NMOBs), its obtaining process and its applications aimed at removing pollutants from water. FUNDAMENTALS OF THE INVENTION

[002] Water pollution is a serious environmental and public health problem caused by the discharge of harmful substances into bodies of water such as rivers, lakes, oceans, and aquifers. These compounds can include industrial waste, agricultural residues, untreated domestic sewage, among others. Water pollution can cause various damages to aquatic life, including the death of fish, aquatic plants, and other organisms, affecting ecosystems and biodiversity, as well as contributing to the emission of greenhouse gases. Furthermore, pollution impacts human health, causing diseases such as dysentery, hepatitis, leptospirosis, and others. In addition, water pollution can harm the fishing, tourism, and recreational industries, damaging local and regional economies. Water pollution can also impact soil quality, as chemical substances and heavy metals can also be released into the soil. Petition 870240111423, dated 12 / 31 / 2024, page 11 / 40 2 / 22 can seep into the soil near contaminated water sources, making it unsuitable for agriculture.

[003] In the removal of organic pollutants, mainly trace contaminants, activated carbon, membrane filtration and the addition of chemicals such as chlorine are already used. However, these methodologies are limited, inefficient for some pollutants and, in most cases, unsustainable.

[004] The association of carbon nanotubes (CNTs) and synthetically derived magnetic nanoparticles has already been described and applied in the removal of pollutants.

[005] Carbon nanotubes (CNTs) are cylindrical allotropes of carbon, which can be single-walled or multi-walled. Carbon is one of the most abundant elements in the universe, and is an extremely interesting element, especially in relation to its chemical bonds. When carbon atoms bond together, compounds with entirely different structures and properties can be generated, and the main characteristic that differentiates these structures is the number of carbon atoms present. Carbon nanotubes are elongated fullerenes that can be seen as layers of graphite rolled into cylinders, and there are two types of carbon nanotubes: single-walled carbon nanotubes (SWNTs) and multi-walled carbon nanotubes (MWNTs). The walls of the nanotube are organized Petition 870240111423, dated 12 / 31 / 2024, page 12 / 40 3 / 22 concentrically, they can acquire different configurations: armchair, zigzag, and chiral. They can be conductors or semiconductors, depending on the winding angle and the radius of the CNT, which makes them excellent candidates for the production of sensors.

[006] Magnetic nanoparticles are nanometer-sized particles with properties that respond to a magnetic field. These nanoparticles can be synthesized in the laboratory using different techniques, such as co-precipitation, hydrothermal methods, thermal decomposition, sol-gel processes, among others. The most widely used is co-precipitation, which involves the addition of two metallic precursors to precipitate the nanoparticle, and in most cases depends on an inert atmosphere and specific equipment, as well as generating chemical waste. Generally, it is a laborious process that generates very small particles (around 10 nm). To increase the size of these nanoparticles, an additional growth step is necessary, which is quite time-consuming. Furthermore, nanoparticles generated through chemical synthesis require another coating step with a polymer for many technological applications, which ends up being the most expensive part of the process.Furthermore, the degradation of dyes by NMOBs appears to involve the natural membrane surrounding the crystal, since its efficiency is greater than that of uncoated synthetic nanoparticles. The method of functionalizing CNTs with synthetically derived magnetic nanoparticles was used as the basis for this development. Petition 870240111423, dated 12 / 31 / 2024, page 13 / 40 4 / 22 of this invention requires that its synthesis be carried out simultaneously with the functionalization, generating small, highly agglomerated particles, which increases the available contact surface of the nanoparticles for interaction with other molecules. In many cases, a limiting factor is the reusability rate and the criteria used to consider reuse efficiency high.

[007] NMOBs, also known as magnetosomes, can be extracted from magnetotactic bacteria cultivated in a bioreactor. These bacteria are commonly found in nature in a wide variety of aquatic environments. The most commonly used cultivable species in biotechnology are Magnetovibrio blakemorei strain MV-1, Magnetofaba australis strain IT-1, Magnetospirillum gryphiswaldense strain MSR-1, and Magnetospirillum magneticum strain AMB-1. These biologically derived nanoparticles already possess their natural coating derived from the cell's plasma membrane. The shape of these nanoparticles is extremely specific and differs from synthetic magnetite nanoparticles, guaranteeing unique and advantageous physicochemical, biological, and magnetic properties for proposed applications. For example, the perfect shape with well-defined faces makes NMOBs stable and resistant to deterioration. Furthermore, the production of NMOBs is a green technology.

[008] In view of the aforementioned problems, the present invention reports a nanocomposite based on the functionalization of carbon nanotubes (CNTs) or allotropes thereof with Petition 870240111423, dated 12 / 31 / 2024, page 14 / 40 5 / 22 magnetic nanoparticles of biological origin (NMOBs), their production process and their use. The nanocomposite aims to be used in water treatment applications, removing pollutants from water. Furthermore, the functionalization of CNTs with magnetosomes is carried out directly through a process that eliminates the need to coat the nanoparticle, reducing a step in the process and making it more efficient and less costly. In addition, the nanocomposite of the present invention is considered sustainable and has superior durability due to the use of NMOBs which, unlike synthetic particles, do not undergo oxidation processes in aqueous medium.

[009] Thus, in the present invention, carbon nanotubes (CNTs) functionalized with magnetic nanoparticles of biological origin (NMOBs), also known as magnetosomes, were used which, due to their properties such as degradation of dyes and organic compounds, 100% biological nature, high chemical purity, crystallographic perfection, presence of a biological membrane with proteins of biotechnological interest and thermal and oxidative resistance, facilitate the decontamination of water. The aforementioned nanocomposite demonstrated remarkable effectiveness in the removal / elimination of pollutants and high reusability with more than 6 reuse cycles with high efficiency, in addition to being a promising solution in water treatment. STATE OF THE ART Petition 870240111423, dated 12 / 31 / 2024, page 15 / 40 6 / 22

[0010] Document WO2015135068 develops the functionalization of CNTs with micro-silica nanoparticles. Silica is a mineral, composed of silicon dioxide and abundant on the Earth's surface; this material does not contain ferric particles like magnetite, and in this case, silica microspheres are used together with a carbonaceous material, developing a kind of core-shell to improve the physicochemical properties of the material.

[0011] However, advantageously, the present invention does not involve the use of silica in its composition or process, nor does it require a coating due to the natural presence of a lipid membrane. Furthermore, the aforementioned document does not mention the origin of the magnetic nanoparticles, whereas in the case of said document, the use of magnetic nanoparticles is not essential, unlike the present invention, which specifies the use of magnetic nanoparticles of biological origin as essential for this process. Moreover, the present invention demonstrates excellent removal results (> 80%) and high reusability (> 6 cycles with efficiency > 80%).

[0012] The article “Sorting Carbon Nanotubes and their Biological Applications”, published by Hyunkyu Oh Sang-Yong Juno on the Merck website, teaches the oxidation of CNTs and functionalization with oxygenated species. This article also describes non-covalent bonding as preferred. Petition 870240111423, dated 12 / 31 / 2024, p. 16 / 40 7 / 22

[0013] However, this article differs from the present invention since the present invention functionalizes with NMOBs, i.e., magnetosomes, which are organelles with magnetic properties, which are not mentioned or used in the aforementioned article. Furthermore, the present invention does not propose a medical approach, but rather an environmental one, for the treatment and monitoring of pollutants. Also, the aforementioned article describes non-covalent bonding as preferred, while the present invention teaches functionalization by covalent bonds between CNTs and magnetosomes, involving the membrane that surrounds them. CNTs have physicochemical properties described and well established in the literature; however, when associated with NMOBs, they undergo changes in their properties, making a significant improvement in their applications possible, such as magnetic concentration.

[0014] Document WO2015044964 describes capped magnetic nanoparticles and an adsorbent for use in the adsorptive separation of dyes from polluted water and magnetic separation of adsorbed dye from purified / decolorized water, wherein the nanoadsorbent may be, among others, carbon nanotubes. The document reveals that the magnetic nanoparticles are Fe3O4 and that they are protected by a polymer.

[0015] However, this document differs from the present invention since the present invention teaches the functionalization of NMOBs with carbon nanotubes, without any type of coating. Petition 870240111423, dated 12 / 31 / 2024, page 17 / 40 8 / 22 artificial. Unlike the nanoparticles used in the aforementioned document, the NMOBs of the present invention are already coated with a natural biological membrane derived from the cytoplasmic membrane; therefore, the present invention does not teach the nanoparticle coating process. Thus, the main advantage of using the NMOBs of the present invention is the elimination of the nanoparticle coating step, since they are naturally covered by a lipid membrane, thereby facilitating their functionalization, eliminating expenses with chemical products and reagents used in particle coating and consequently reducing production costs. Another advantage is that the NMOBs of the present invention are environmentally friendly.

[0016] Document BR 102020015831-7 A2, belonging to the same research group as the inventors of the present invention, teaches only the production of magnetosomes (NMOBs) through the cultivation of the bacterium of the species Mv. blakemorei strain MV-1. It has bioreactors for the production of magnetotactic bacteria and consequently, the production of NMOBs on a large scale.

[0017] However, the present invention utilizes NMOBs already produced by bioreactors or culture flasks and synthesizes them to obtain functionalized NMOBs (CNTs with NMOBs) with the specific objective of removing certain pollutants from water. Therefore, while the aforementioned document focuses only on the cultivation of the microorganism, the present invention Petition 870240111423, dated 12 / 31 / 2024, page 18 / 40 9 / 22 aims to utilize functionalized NMOBs in CNTs, that is, after the cultivation, purification, and synthesis processes. Therefore, the aforementioned document and the present invention present different technical problems and seek completely distinct technical solutions.

[0018] Document WO2019106428 describes the medical and cosmetic application of magnetosomes, more specifically, the application of these nanoparticles in the human body for the treatment of diseases (hyperthermia), cosmetic use and other medical applications.

[0019] However, this document differs from the present invention since the present invention aims at the applicability of NMOBs only for environmental applications, specifically, for water treatment. Furthermore, the aforementioned document does not cover functionalization with carbon nanotubes, thus differing from the present invention.

[0020] Therefore, it can be concluded that the present invention differs from the prior art documents presented here, since none of them refers to the process of functionalizing carbon nanotubes (CNTs) with magnetic nanoparticles of biological origin (NMOBs) or magnetosomes, resulting in a nanocomposite for the elimination of polluting compounds in water. The functionalization process of the present invention is done directly between the CNTs and the magnetosome, eliminating the need to functionalize the CNTs with silica nanoparticles and, consequently, reducing a step in the process. With this, Petition 870240111423, dated 12 / 31 / 2024, page 19 / 40 10 / 22 The present invention surprisingly eliminates the coating step of the nanoparticles. In addition to providing a more efficient and less costly functionalization process, the nanocomposite has an advantage over other products because it demonstrates excellent results in removing / eliminating pollutants by more than 80%, and high reusability with more than 6 reuse cycles with efficiency above 80%. SUMMARY OF THE INVENTION

[0021] The present invention applies to the field of biotechnology and water treatment, being intended for applications aimed at removing or eliminating pollutants from water, such as dyes and organic pollutants.

[0022] Although combinations of carbon nanotubes and synthetic magnetic nanoparticles have been described and applied in the removal of pollutants, they generate chemical waste and have a low reusability rate. To solve this problem in the prior art, the present invention reports a nanocomposite of carbon nanotubes (CNTs) or allotropes thereof functionalized with bio-derived magnetic nanoparticles (BNMs), its process for obtaining it through direct functionalization, using a simpler and less costly process, and its applications for the removal of pollutants from water. BRIEF DESCRIPTION OF THE FIGURES

[0023] The invention could be better understood through the brief description of the following figures: Petition 870240111423, dated 12 / 31 / 2024, p. 20 / 40 11 / 22

[0024] Figures 1A-E show transmission electron microscopy (TEM) images illustrating the interaction between the NMOB membrane from the Magnetospirillum magneticum cepa AMB-1 species and the carbon nanotube, with 50 nm (Figure 1A), 20 nm (Figure 1B) and 10 nm (Figures 1C-E).

[0025] Figure 2 illustrates the magnetic concentrating capacity of the nanocomposite.

[0026] Figures 3A-D show scanning transmission electron microscopy (STEM) images of the nanocomposite showing the interaction between NMOBs from the species Magnetovibrio blakemorei cepa MV-1T and the carbon nanotube.

[0027] Figure 4 presents a degradation graph (%) of the methyl blue dye by the nanocomposite using NMOBs from three different species. Legend: CNT@MV-1 (orange) = carbon nanotube functionalized with NMOB from Magnetovibrio blakemorei strain MV-1T; CNT@IT-1 (dark blue) = carbon nanotube functionalized with NMOB from Magnetofaba australis strain IT-1; CNT@AMB-1 (turquoise blue) = carbon nanotube functionalized with NMOB from Magnetospirillum magneticum cepa AMB-1; MV-1 (pink) = non-functionalized NMOB derived from Magnetovibrio blakemorei cepa MV-1T; IT-1 (purple) = non-functionalized NMOB derived from Magnetofaba australis cepa IT-1; AMB-1 (green) = non-functionalized NMOB Petition 870240111423, dated 12 / 31 / 2024, page 21 / 40 12 / 22 functionalized from Magnetospirillum magneticum cepa AMB-1; MNP (gray) = synthetic magnetic nanoparticle; and CNT (yellow) = non-functionalized carbon nanotube.

[0028] Figure 5 presents a graph of the nanocomposite's reusability in the degradation (%) of methyl blue dye using NMOBs of three different species. Legend: CNT@MV-1 (pink) = carbon nanotube functionalized with NMOB derived from Magnetovibrio blakemorei strain MV-1T; CNT@IT-1 (purple) = carbon nanotube functionalized with NMOB from Magnetofaba australis strain IT-1; and CNT@AMB-1 (orange) = carbon nanotube functionalized with NMOB from Magnetospirillum magneticum strain AMB-1. DETAILED DESCRIPTION OF THE INVENTION

[0029] The invention may be better understood through the following detailed description, in accordance with the attached figures.

[0030] The present invention describes a method for obtaining a magnetic nanocomposite based on the functionalization - or association - of carbon nanotubes (CNTs) with (or to) magnetic nanoparticles of biological origin (NMOBs), and its applications aimed at water treatment. According to the present invention, the terms nanohybrid and nanotool are interchangeable with nanocomposite.

[0031] The aforementioned method is based on the acidification process of nanotubes.

[0032] The method for obtaining the magnetic nanocomposite of the present invention comprises the following steps: Petition 870240111423, dated 12 / 31 / 2024, p. 22 / 40 13 / 22

[0033] (a) adding a strong acid to a solution of carbon nanotubes (CNTs) or allotropes thereof;

[0034] (b) washing the carbon nanotube (CNT) solution with deionized water;

[0035] (c) filter, dry and solubilize the carbon nanotube (CNT) solution in a mixture of polar solvents;

[0036] (d) functionalize the carbon nanotube (CNT) solution with a solution of bio-derived magnetic nanoparticles (BNMs), resulting in a magnetic nanocomposite.

[0037] Carbon nanotubes (CNTs) are considered allotropes of carbon, such as graphene, graphite, fullerene, diamond, or combinations thereof. Preferably, the carbon nanotube (CNT) comprises being a fullerene nanotube.

[0038] In step (a), a quantity ranging from 25 mg to 1,000 mg, preferably 25 mg, of carbon nanotubes is added to a solution of 5 mL to 200 mL, preferably 5 mL, of a strong acid in a 50 mL volumetric flask or in a glass beaker, Erlenmeyer flask, or any other glass laboratory container. The nanotubes are mixed with the strong acid to expose functional groups. The mixtures are left in an ultrasonic bath or under magnetic stirring, maintaining refrigeration with ice, as it is an exothermic solution, for a period of 3.8 hours to 4.2 hours, preferably 4 hours. Petition 870240111423, dated 12 / 31 / 2024, page 23 / 40 14 / 22

[0039] The strong acid may be selected from the group comprising nitric acid, sulfuric acid, perchloric acid, hydrobromic acid, hydroiodic acid, or combinations thereof. Preferably, the acid is nitric acid or sulfuric acid. Even more preferably, for greater preservation of the nanotube structure, the acid used is nitric acid.

[0040] In step (b), the treated CNTs can be decanted and washed with deionized water 6 to 10 times, preferably 6 times, until they reach a pH greater than 5, preferably a pH between 6.5 and 7.5, with the washes being carried out at intervals of 8 to 12 hours, preferably 12 hours (overnight).

[0041] In step (c), the CNTs can be filtered through a membrane with a thickness of 0.22 µm to 0.45 µm, preferably 0.22 µm, and dried in an oven or vacuum drying for a period of 24 hours to 72 hours, preferably 24 hours, and subsequently solubilized in a mixture of polar solvents in a ratio ranging from 1:1 to 1:2, preferably 1:1. The solvents in the polar solvent mixture can be selected from a group comprising ethanol and water, methanol and water, acetone and water, preferably ethanol and water.

[0042] In step (d), the NMOBs are added to the CNT solution, obtaining a solution of NMOBs and CNTs in an NMOB:CNT ratio that can vary from 2:1 to 5:1, being Petition 870240111423, dated 12 / 31 / 2024, page 24 / 40 15 / 22 preferably 4:1, which is left in an ultrasonic bath or magnetic stirring at room temperature for a period ranging from 30 to 70 minutes, preferably 1 hour, for functionalization.

[0043] NMOBs can be extracted from magnetotactic bacteria cultivated in a bioreactor. The magnetotactic bacteria can be selected from a group comprising Magnetovibrio spp., Magnetofaba spp., Magnetospirillum spp., Magnetococcus spp., Desulfovibrio spp., Magnetospira spp., or combinations thereof. Preferably, the magnetotactic bacteria can be selected from a group comprising Magnetovibrio blakemorei, Magnetofaba australis, Magnetospirillum gryphiswaldense, Magnetospirillum magneticum, Magnetococcus marinus, Desulfovibrio magneticus, Magnetospira thiophila, or combinations thereof. More preferably, the magnetotactic bacterium is selected from Magnetovibrio blakemorei strain MV-1T, Magnetofaba australis strain IT-1, Magnetospirillum gryphiswaldense strain MSR-1, and Magnetospirillum magneticum strain AMB-1. Even more preferably, the magnetotactic bacterium is Magnetospirillum magneticum strain AMB-1.

[0044] Before being added to the CNT solution, the NMOBs are purified and solubilized in HEPES buffer solution (10 nM, pH 7.0). The NMOB purification process is based on centrifuging the medium containing the cells, disrupting them through sonication with a pipette tip. Petition 870240111423, dated 12 / 31 / 2024, page 25 / 40 16 / 22 intervals of 30 seconds for 1 hour at 40% amplitude, followed by magnetic concentration. The material is washed with 10mM HEPES + 20 mM NaCl at least 4 times, interspersed with magnetic concentrations, followed by two washes with ultrapure water. The quality of the purification is then evaluated by transmission electron microscopy.

[0045] The magnetic nanocomposite of the present invention can be used in the removal of dyes and organic pollutants from water samples. The dyes can be selected from the group comprising methyl blue, methylene blue, aniline blue, methyl violet, Coomassie blue or other dyes commonly used in textile industries and processes or combinations thereof, preferably methyl blue.Organic pollutants can be selected from the group comprising beta-blockers, such as atenolol, sotalol, metoprolol, propranolol, bisoprolol, nadolol, nebivolol; or endocrine disruptors, such as ethinylestradiol, estradiol, norgestrel, progesterone, testosterone, androsterone. EXAMPLES

[0046] EXAMPLE 1 - Obtaining carbon nanotube (CNT) nanocomposites functionalized with magnetic nanoparticles of biological origin (NMOBs):

[0047] Between 25 mg and 1000 mg of carbon nanotubes (CNTs) (Sigma Aldrich) were added to 5 mL - 200 mL of nitric acid or sulfuric acid each in a volumetric flask. Petition 870240111423, dated 12 / 31 / 2024, page 26 / 40 17 / 22 of 50 mL individually (either a beaker or a glass Erlenmeyer flask (glass laboratory container)). The mixtures were left in an ultrasonic bath for 3.8 to 4.2 hours, maintaining refrigeration with ice, to expose functional groups on the nanotubes, especially carboxyl and terminal -OH groups. It should be noted that if the functional groups are not exposed, the magnetosomes will not adhere to the nanotube. Therefore, this is essential for functionalization to occur.

[0048] Next, the treated CNTs were decanted and washed with deionized water approximately 6 to 10 times, until a pH between 6.5 and 7.5 was reached, with washes performed at intervals of 12 to 48 hours. Then, the CNTs were filtered through a 0.22 to 0.45 µm membrane and dried in an oven for 24 hours, subsequently being solubilized in a mixture of ethanol, methanol or acetone and water in proportions ranging from 1:1 to 1:2 solvent.

[0049] Magnetotactic bacteria of the species Magnetospirillum magneticum strain AMB-1 were cultivated in a bioreactor using an optimized medium according to Heyen and Schüller (Applied microbiology and biotechnology, 2003, 61:536-544). In more detail, M. magneticum strain AMB-1 was cultivated in a medium containing 35 g of potassium lactate, 100 mL of 10 mM iron citrate, 1 g of KH2PO4, 1.5 g of MgSO4.7H2O, 23.8 g of HEPES, 3.4 g of NaNO3, 1 g of yeast extract, 30 g of peptone, and 50 mL of EDTA-TES to a final volume of 10 liters. The pH was then adjusted. Petition 870240111423, dated 12 / 31 / 2024, page 27 / 40 18 / 22 to pH 6.75, autoclaved and purged with nitrogen gas and nitrous oxide gas. Additionally, because they are different species and have different nutritional needs and physicochemical conditions, the magnetotactic bacteria of the species Magnetovibrio blakemorei strain MV1T were cultivated in a bioreactor using an optimized medium.

[0050] The extraction is performed according to the following description. For 10 L of medium, 2 g of sodium acetate, 5 g of sodium succinate, 2.5 g of ammonium chloride, 5 g of hydrolyzed casein, 50 mL of Wolfe mineral solution, 10 g of yeast extract, and 30 g of peptone are used. The bioreactor is autoclaved, and then the following sterilized reagents are added: 15 mL of phosphate buffer, 24 mL of sodium bicarbonate (0.3 M), L-cysteine ​​at 0.2 g / L, 24 mL of ferrous sulfate (10 mM), and 4.6 mL of vitamin solution. After the process, the pH is adjusted to 7.2 using 2N NaOH or 2N HCl, depending on whether the final pH is more acidic or basic.

[0051] NMOB extraction is performed by centrifuging the culture medium containing the bacterial growth, followed by sonication in a pipette tip for 1 hour at 40% power, with sonication intervals and a 30s pause. Afterward, the material is magnetically concentrated overnight, followed by at least 5 washing steps in HEPES + NaCl (10 mM and 20 mM), interspersed with magnetic concentrations, and a final wash in MilliQ water. Petition 870240111423, dated 12 / 31 / 2024, page 28 / 40 19 / 22

[0052] After extraction and solubilization in HEPES buffer, a solution of NMOBs and CNTs (5:1, 4:1, 3:1 and 2:1) was obtained, which was left in an ultrasonic bath, and could also be left in magnetic stirring, at room temperature for 30 to 70 min for functionalization.

[0053] The interaction between the NMOB membrane from the Magnetospirillum magneticum cepa AMB-1 species and the carbon nanotube was evaluated by transmission electron microscopy (Figures 1A-E).

[0054] The interaction between NMOBs from the species Magnetovibrio blakemorei strain MV-1T and the carbon nanotube was evaluated by transmission scanning electron microscopy (Figures 3A-D).

[0055] EXAMPLE 2 - Evaluation of the degradation of methyl blue dye by nanocomposites:

[0056] Nanocomposites (40 mg / L, ranging from 40 to 80 mg / L) were added to a methyl blue solution (15 mg / L, ranging from 15 to 30 mg / L) and stirred for 1 to 5 minutes to allow the dye to interact with the nanotool. Dye discoloration was observed, which was confirmed by optical density analysis using aliquots (700 - 1000 pL) in a spectrophotometer at a wavelength of 600-665 nm for 5 to 10 minutes, which is within the wavelength range of blue dyes.

[0057] EXAMPLE 3 - Evaluation of the reusability of nanocomposites: Petition 870240111423, dated 12 / 31 / 2024, pp. 29 / 40 20 / 22

[0058] After defining 5 minutes as sufficient to degrade the dye, reuse tests of the nanocomposites were carried out by magnetically concentrating them and adding a new methyl blue solution (15 mg / mL), so that the reuse tests for evaluating the reusability of the tool were carried out under the same conditions as the previous test (example 2 - evaluation of the degradation of methyl blue dye by nanocomposites). RESULTS

[0059] Figures 1A-E and 3A-D show, using transmission electron microscopy, the interaction between carbon nanotubes and NMOBs of the species Magnetospirillum magneticum cepa AMB-1 and Magnetovibrio blakemorei cepa MV-1, respectively, as well as the arrangement of the crystals in the nanotube. It is possible to observe that the membrane covering the NMOBs remains after functionalization and interacts chemically with the carbon nanotube. Specifically in Figure 1C, it is possible to identify the membrane between the NMOB and the nanotube using high-resolution transmission electron microscopy.

[0060] Figure 2 showed the magnetization of the nanotool. It was possible to observe the dark mass concentrating near the magnet.

[0061] High degradation rates were observed as early as the first minute (Figure 4): 85.9% (CNT@MV-1), 85.3% (CNT@IT1) and 87.5% (CNT@AMB-1). After 5 minutes, degradation rates reached approximately 100%, reaching 92.9% (CNT@MV-1). 21 / 22 1), 92.3% (CNT@IT-1), 98.2% (CNT@AMB-1). It is worth noting that the membrane proteins of the NMOBs exert a degradation or adsorption effect on pollutants. Furthermore, the presence of CNTs aids in the uniform arrangement of particles, as well as the exposure of surface areas, maintaining high dye decolorization rates. The great advantage of using the nanocomposite is the need for lower concentrations of NMOBs, since, at the same concentration, the nanocomposite and pure NMOBs have similar effects. Additionally, it is possible to reuse the nanocomposite more times (> 6 cycles) than pure NMOBs (4 cycles).

[0062] Thus, it is also noted that the NMOBs alone had a similar efficiency to the nanocomposite, due to the greater mass of NMOBs, since, at the same concentration used, the mass of NMOBs in the nanocomposite is 3 / 4 of the mass of control NMOBs. Reinforcing the advantage of the nanocomposite, which needs fewer NMOBs to generate high efficiency. The CNTs alone do not generate practically any type of discoloration, which reinforces the existence of a synergism between the CNT and the NMOB, increasing its efficiency. The MNPs are not coated by any extra layer, thus showing the importance of the NMOB membrane in the degradation of the pollutant.

[0063] Regarding the reusability of the nanocomposite, 6 reuse cycles were achieved and efficiency rates >90% in the degradation of pollutants were observed in all cycles (Figure 6). Petition 870240111423, dated 12 / 31 / 2024, p. 31 / 40 22 / 22

[0064] Therefore, the present invention has developed a more efficient method (with fewer steps) for obtaining nanocomposites, which are obtained from the functionalization of carbon nanotubes with magnetic nanoparticles of biological origin (NMOBs), and the use of these nanocomposites in the degradation of dyes with a high removal rate and reusability with excellent efficiency.

[0065] The nanocomposites of the present invention can also be used to remove other organic pollutants, such as dyes, endocrine disruptors, and pharmaceuticals from contaminated water samples. Examples of pharmaceuticals that can be removed by the nanocomposite of the present invention are metoprolol, atenolol, propranolol, sotalol, and ethinylestradiol.

[0066] The present invention has been disclosed in this descriptive report in terms of its preferred embodiment. However, other modifications and variations are possible from the present description, and are still within the scope of the invention disclosed herein. Petition 870240111423, dated 12 / 31 / 2024, pp. 32 / 40

Claims

1 / 4 CLAIMS 1. A process for obtaining a magnetic nanocomposite, CHARACTERIZED by comprising the steps: (a) adding a strong acid to a solution of carbon nanotubes (CNTs) or allotropes thereof; (b) washing the carbon nanotube (CNT) solution with selected deionized water; (c) filtering, drying and solubilizing the carbon nanotube (CNT) solution in a mixture of polar solvents; (d) functionalizing the carbon nanotube (CNT) solution with a solution of magnetic nanoparticles of biological origin (NMOBs), resulting in a magnetic nanocomposite.

2. Process according to claim 1, CHARACTERIZED in that in step (a), an amount of 25 mg to 1,000 mg of carbon nanotubes (CNTs) is added to a solution of 5 mL to 200 mL of a strong acid in a container, the mixtures being kept in an ultrasonic bath or under magnetic stirring with ice cooling for a period of 3.8 hours to 4.2 hours.

3. Process, according to claims 1 and 2, CHARACTERIZED in that in step (b), the treated CNTs are decanted and washed with deionized water 6 to 10 times, until they reach a pH greater than 5, preferably a pH between 6.5 and 7.5, with the washes being carried out at intervals of 8 to 12 hours. Petition 870240111423, dated 12 / 31 / 2024, page 33 / 40 2 / 4 4. Process, according to any one of claims 1 to 3, CHARACTERIZED in that in step (c), the CNTs are filtered through a membrane with a thickness of 0.22 µm to 0.45 µm, and dried in an oven or by vacuum drying for a period of 24 hours to 72 hours, and subsequently solubilized in a mixture of polar solvents in a ratio ranging from 1:1 to 1:

2.

5. Process, according to any one of claims 1 to 4, CHARACTERIZED in that in step (d), the NMOBs are added to the CNT solution, obtaining a solution of NMOBs and CNTs in an NMOB:CNT ratio that can vary from 2:1 to 5:1, which is left in an ultrasonic bath or under magnetic stirring at room temperature for a period ranging from 30 minutes to 70 minutes.

6. Process, according to any one of claims 1 to 5, CHARACTERIZED in that: the carbon nanotubes (CNTs) further comprise allotropes of carbon such as graphene, graphite, fullerene, diamond, or combinations thereof, preferably the carbon nanotube (CNT) comprises being a fullerene nanotube; the strong acid is selected from the group comprising nitric acid, sulfuric acid, perchloric acid, hydrobromic acid, hydroiodic acid, or combinations thereof, preferably nitric acid; the solvents of the polar solvent mixture are selected from the group comprising ethanol and water, methanol and water, acetone and water, preferably ethanol and water.

7. Magnetic nanocomposite, obtained as defined in any one of claims 1 to 6, CHARACTERIZED by being obtained from the functionalization of carbon nanotubes (CNTs) with magnetic nanoparticles of biological origin (NMOBs).

8. Nanocomposite, according to claim 7, CHARACTERIZED by achieving 6 reuse cycles with efficiency >90% in all 6 cycles.

9. Use of the nanocomposite, as defined in any one of claims 1 to 8, CHARACTERIZED by being for water and wastewater treatment.

10. Use, according to claim 9, CHARACTERIZED by the fact that the treatment of water and effluents involves the removal of dyes, organic pollutants and pharmaceuticals.

11. Use, according to claims 9 and 10, CHARACTERIZED in that: the dyes may be selected from the group comprising methyl blue, methylene blue, aniline blue, methyl violet, Coomassie blue or other dyes commonly used in textile industries and processes, or combinations thereof, preferably methyl blue; the organic pollutants may be selected from the group comprising beta-blockers, such as atenolol, Petition 870240111423, dated 12 / 31 / 2024, page 35 / 40 4 / 4 sotalol, metoprolol, propranolol, bisoprolol, nadolol, nebivolol; or endocrine disruptors, such as ethinylestradiol, estradiol, norgestrel, progesterone, testosterone, androsterone; and the drugs may be selected from the group comprising metoprolol, atenolol, propranolol, sotalol, ethinylestradiol. Petition 870240111423, dated 12 / 31 / 2024, pp. 36 / 40

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