MOF-type organometallic material, manufacturing process and fertilization process

Abstract

Organometallic material of the MOF type, manufacturing process and fertilization process. The present invention relates to a composition for the direct, one-step, room-temperature formation of an amorphous MOF based on humic acids, consisting of a phospho-metal-humic complex. Furthermore, the present invention relates to the process for obtaining this composition and its use for the efficient fertilization of crops. Fig. 13.

Description

Title of the invention: MOF-type organometallic material, manufacturing process and fertilization process. Technical field

[0001] The present invention relates to materials whose structure comprises an organo-metallic network (“Metal Organic Framework” in English and whose acronym is MOF) derived from the complexation of phosphorus and nitrogen sources with a humic system via metallic bridges.

[0002] Furthermore, the present invention relates to a method of manufacturing this product which can be used as fertilizer for plant nutrition. Previous technique

[0003] Solid organometallic networks (MOFs) are porous crystalline materials composed of a metal that acts as a node and a polydentate organic ligand that binds the metal. The self-assembly of the metal and the organic ligand generates a one-, two-, or three-dimensional network. This structure includes internal coordination bonds and intermolecular and weak bonds (hydrogen bonds or Pi-Pi interactions). The metal and organic ligand in the MOF can vary, with iron(III) being the most commonly used metal. The most common organic ligands are carboxylic acids, pyridines, cyano compounds, polyamines, benzenes, sulfonates, and ethers. Among the carboxylic acids, benzene derivatives of carboxylic acid, ethylenediaminetetraacetic acid, oxalic acid, and citric acid have been studied.

[0004] MOF materials are characterized by high porosity, high chemical stability, and high thermal stability. Due to their large surface area, large pore size, and crystalline nature, MOF materials allow molecules or ions to be incorporated both into the atomic lattice comprising the metal and the organic ligand, and into the internal cavities of the crystals. These unique properties offer a wide range of functionalities and technical applications for MOFs, such as gas storage, drug delivery, and toxin removal. The use of MOFs as fertilizers has also been investigated.

[0005] For example, Anstoetz M. et al. reported in Journal of Material Science, 2016;51(20):9239-52 and in PLOS One, 2015 Dec 1; 10(12) the synthesis and characterization of a MOF using oxalic acid as an organic ligand. Phosphate and amine were then added to the MOF, resulting in an oxalate-phosphate-amine MOF (OPA-MOF). The authors also investigated the properties of this particular MOF as a slow-release nitrogen and phosphorus fertilizer. They observed that the structure of this OPA-MOF is crystalline and comprises FeO6 units with bidentate oxalate bridges linking adjacent iron centers. Furthermore, the PO4 units share their oxygens with the FeO6 units. OPA-MOFs have a very stable crystalline morphology. However, they have the disadvantage of being poorly soluble and having a low capacity to encapsulate bioactive substances. The authors demonstrated that urea hydrolysis is rapid with OPA-MOF, while the conversion of ammonium to nitrate is significantly lower compared to urea alone. However, phosphorus uptake and yield with OPA-MOF treatment are considerably lower than those obtained with conventional fertilizer treatment.In conclusion, OPA-MOF has shown potential as a nitrogen fertilizer but suffers from low phosphorus bioavailability.

[0006] Later, CN111574284 described the synthesis of MOFs using citric acid instead of oxalic acid as the organic ligand of the carboxylic acid. Phosphate and urea were also included in the MOF to obtain a citrate-phosphate-amine MOF.

[0007] Prior art carboxylic acid MOFs have several drawbacks. They are prepared using a complicated and expensive hydrothermal method. This method involves several steps, requires high temperatures and pressures, and expensive reagents.

[0008] In particular, carboxylic acid-based MOF fertilizers such as prior art oxalate-phosphate-amine MOF and citrate-phosphate-amine MOF are expensive to produce, making them difficult to apply on a large scale in the agrochemical field. Furthermore, these MOFs are poorly soluble in water and have low phosphorus bioavailability.

[0009] Another recent variant of MOF, called "amorphous MOF," retains the constituent elements and connectivity of crystalline lenses without large-scale periodic order. They are generally obtained by amorphizing a crystalline MOF by applying pressure, heating, ball milling, grinding, radiation, or electrical discharge. For example, Lohe et al. reported a two-step synthesis of a benzene tricarboxylic acid-iron nitrate MOF aerogel for catalytic applications in Chem. Commun. 2009, 40: 6056. The two-step protocol combines sol-gel and supercritical CO2 drying. The amorphous structure of such a MOF has been considered a problem to be solved. Another amorphous MOF based on an alginate-benzene tricarboxylic acid-iron-ammonium MOF aerogel was prepared by Wu et al. (Int. J. Biol. Macromol., 2020 Feb, 15:145:1073-1079) and proposed as a slow-release fertilizer.

[0010] Amorphous MOFs are prepared by a two-step synthesis comprising a chemical reaction to create a crystalline MOF and subsequent processing of the crystalline MOF using an energy-intensive method. This method prevents the large-scale production required in most industrial sectors.

[0011] It is therefore necessary to propose new MOF products that can be produced under mild synthesis conditions, with a limited number of steps, using inexpensive reagents and non-toxic solvents. It would be advantageous to propose a method for manufacturing an MOF product that is inexpensive and allows for large-scale MOF production.

[0012] Furthermore, it would be advantageous to propose a phosphorus-amine-metal MOF with improved fertilizing properties, such as high phosphorus bioavailability. Description of the invention

[0013] The present invention provides a solution to these needs and relates to a simple method for preparing an organometallic compound, such as a phosphorus-amine MOF material, without having to resort to energy-intensive physical treatments and several chemical steps.

[0014] The method of the invention is environmentally friendly and cost-effective. Indeed, only one chemical step is required, and it uses a solvent precipitation process. Water can advantageously be used as the solvent. The method may also include a physical step of separating the solid precipitate from the liquid phase.

[0015] The manufacturing method for the material can advantageously be carried out at low temperature. In contrast, the prior art oxalate-phosphoramine and citrate-phosphoramine MOFs require high temperatures and pressures, as well as several steps.

[0016] The invention also provides an organometallic material containing phosphorus and amine that has the characteristic of incorporating humic acid substances as polydentate organic ligands to form a material having a MOF structure. Humic acids, which occur in nature, are inexpensive and environmentally friendly.

[0017] The humic-based phosphorus-amine MOF product may include amorphous domains, particularly due to the incorporation of humic substances, which offers several advantages. First, the MOF-type materials of the invention can provide more bioavailable nitrogen and phosphorus. Second, they can encapsulate bioactive substances. For example, various biomolecules that stimulate plant growth can be inserted. In addition, phosphorus and nitrogen nutrients are inserted into the MOF structure, resulting in a monolithic fertilizer composition with a homogeneous nutrient distribution. Brief description of the drawings

[0018] The [Fig. 1] is a diagram representing several steps of a method for manufacturing a MOF product according to the invention.

[0019] The [Fig.2] is an X-ray diffractogram of a physical mixture composed of chemical reagents used to prepare the MOF.

[0020] The [Fig.3] is an X-ray diffractogram of a MOF product according to the invention.

[0021] Figure 4 is a SEM image of a physical mixture composed of chemical reagents used to prepare for the MOF.

[0022] The [Fig.5] is a SEM image of a MOF product according to the invention.

[0023] Figure 6 is an EDX map of a physical mixture composed of chemical reagents used to prepare for the MOF.

[0024] The [Fig.7] is an EDX card of a MOF product according to the invention.

[0025] Figure 8 is an XPS spectrum of a physical mixture composed of chemical reagents used to prepare for the MOF.

[0026] The [Fig.9] is an XPS spectrum of a MOF product according to the invention.

[0027] Fig. 10 presents four curves representing the release kinetics of P from a MOF product according to the invention in different media which differ in pH value.

[0028] The [Fig. 11] is a nitrogen volatilization curve in a soil in the presence of MOF or in the presence of urea.

[0029] Figure 12 compares the weights of the aerial parts of a plant receiving a MOF product according to the invention or a simple superphosphate.

[0030] Figure 13 compares the weight of the roots of a plant receiving a MOF product according to the invention or a simple superphosphate. Description of the implementation methods

[0031] A first object of the invention is an organo-metallic material of the MOF type comprising phosphorus, nitrogen, a humic substance and at least one metal selected from iron, copper, manganese and zinc, this organo-metallic material having a porous structure, said porous structure preferably being at least partially amorphous.

[0032] An “organo-metallic material of the MOF type” is defined in the present invention as a solid porous product comprising inorganic nodes that are linked by polydentate organic ligands in a three-dimensional arrangement. nodes include a metal ion or a metal salt, such as iron phosphate for example.

[0033] The organo-metallic material is preferably a porous material comprising internal pores in its structure. The porosity of the MOF can be measured and / or observed by any method known to those skilled in the art, such as microscopy, the BET (Brunauer, Emmett and Teller) method for measuring specific surface area, the BJH (Barrett, Joyner and Halenda) method for measuring pore size and volume, or the Horvath-Kawazoe (HK) method for measuring pore volume.

[0034] For example, the porosity of the MOF can be at least one physical parameter chosen from specific surface area, pore distribution, mean pore width, mean pore diameter, and pore volume. A porosity value of the MOF can be defined as at least one numerical value of at least one parameter. The porosity value of the MOF can be a set of numerical values ​​of several parameters. The numerical value of a parameter can be an average value or a range of values. The material of the invention advantageously exhibits high internal porosity.

[0035] The porosity value of the MOF can be chosen from an average pore width, an average pore diameter, an average pore volume, or a combination of these values. According to the IUPAC definition, the MOF can be classified as a mesoporous structure when the pores have an average size between 3 nm and 10 nm.

[0036] In a particular embodiment, the average width of the pores of the porous structure is between 3 nm and 10 nm, the average diameter of the pores of the porous structure is between 4 nm and 6 nm and the average volume of the pores of the porous structure is between 0.35 cm3 / g and 0.50 cm3 / g.

[0037] The MOF of the invention may be amorphous or at least partially amorphous in the case where certain periodic units may be present on a limited or large scale. The presence of amorphous domains can be observed by any method known to those skilled in the art, such as X-ray imaging.

[0038] The composition of the MOF product may include 10 to 15% atomic metal, 10 to 15% atomic phosphorus and 10 to 15% atomic carbon.

[0039] The organic ligand present in the MOF product of the invention is a humic substance (HS) which may be a humic acid, a fulvic acid or mixtures thereof.

[0040] Although the structure and properties of a given SH depend on the source of soil and water and the specific extraction conditions, the average properties of SHs from different origins are nevertheless remarkably similar.

[0041] The SH can be extracted from organic matter, such as peat, leonardite, soils, and composts of animal and plant waste, using an alkaline agent such as than sodium hydroxide (NaOH) or potassium hydroxide (KOH). The alkaline organic extract can then be separated by acidification into humic acids (soluble in water at an alkaline pH but insoluble at an acidic pH), fulvic acid (soluble in water at any pH), and humin (residue insoluble in water at any pH). The humic acids can be separated into gray humic acids (insoluble at a neutral pH and an ionic strength greater than 1 M) and brown humic acids (soluble at a neutral pH and an ionic strength greater than 1 M).

[0042] The constituent metal of the MOF, in the case of a single metal, or the constituent metals of the MOF, in the case of several metals, may be chosen from Fe(III), Fe(II), Cu(II), Mn(II), and Zn(II). Calcium and magnesium are not preferred metals for the MOF product of the invention, as they can slow down the formation of the organometallic ligand network. Inorganic salts of calcium and magnesium, such as calcium nitrate, calcium chloride, magnesium nitrate, and magnesium chlorides, tend to flocculate humic acids and form aggregates of high molecular size.

[0043] The chemical composition of the organo-metallic material of the invention can be characterized by a metahphosphorus molar ratio of between 1:4 and 1:1, preferably between 1:3 and 1:2, and preferably about 1:1, and / or a metal-humic substance mass ratio of between 1:5 and 1:2, preferably between 1:4 and 1:2, and preferably about 1:3.

[0044] A second object of the present invention is a method for manufacturing an organo-metallic material comprising a step of preparing an aqueous solution comprising a water-soluble phosphorus compound, a water-soluble nitrogen compound and a water-soluble humic substance, a step of incorporating at least one water-soluble metallic salt into said aqueous solution, and a step of forming a precipitate and an aqueous phase, the incorporation step being stopped when the aqueous phase has a final pH between 3.0 and 9.0.

[0045] The preparation step and the incorporation step of at least one water-soluble metallic salt are preferably carried out by slow and controlled addition. A person skilled in the art will know how to adjust the duration of the incorporation step.

[0046] The organometallic material is advantageously a MOF that is formed simultaneously with the mixture of reactants in the same reactor in the form of a precipitate that can then be separated from the liquid by centrifugation or filtration. Before separating the filtrate, the suspension can be allowed to settle for an appropriate time, preferably 2 hours. According to one embodiment of the invention, the precipitate is separated from the aqueous phase by centrifugation and then dried.

[0047] The reaction is preferably carried out at ambient temperature in any type of stirred reactor. However, the temperature can be raised to a maximum of 100 °C. Therefore, the preparation and incorporation steps can advantageously be carried out at atmospheric pressure and at a temperature below 100 °C, preferably below 60 °C, and even more preferably between 20 °C and 30 °C.

[0048] According to a preferred embodiment, the aqueous solution comprising a water-soluble phosphorus compound, a water-soluble nitrogen compound and a water-soluble humic substance has a pH greater than 7.0.

[0049] The pH of the aqueous solution can be adjusted using an alkaline or acidic solution, as appropriate, during the incorporation step.

[0050] The incorporation step is stopped when the aqueous phase has a final pH between 3.0 and 9.0, preferably between 3.5 and 7.0, and even more preferably between 4.0 and 4.5.

[0051] The quantities of humic substance, metallic salt and phosphorus compound used to prepare the material can be chosen so that the metakphosphorus molar ratio is between 1:4 and 1:1, preferably between 1:3 and 1:2, and preferably about 1:1, and that the metal:humic substance mass ratio is between 1:5 and 1:2, preferably between 1:4 and 1:2, and preferably about 1:3.

[0052] In a particular case, where the material can be used as a fertilizer or can be incorporated into a fertilizer composition, the present description discloses a set of four reagents to be used in a method of manufacturing a fertilizer, the four reagents being a water-soluble source of phosphorus, a water-soluble source of nitrogen, a water-soluble humic substance comprising humic acids and / or fulvic acids, and an aqueous solution of a metal, in which a metal:phosphorus molar ratio is from 1:4 to 1:1, preferably from 1:3 to 1:2, and preferably about 1:1, and in which a metal / humic substance mass ratio is from 1:5 to 1:2, preferably from 1:4 to 1:2, and preferably about 1:3.

[0053] The water-soluble humic substance can be selected from the water-soluble forms of humic acids, fulvic acids, and mixtures thereof. The water-soluble humic substance used to prepare the aqueous solution can be a commercially available product, either as a dry solid or as an aqueous solution of humic substances. Commercially available humic substances include, for example, potassium humates or sodium humates. The manufacturing process of the present invention may also include an additional step of preparing the water-soluble humic substance.

[0054] The water-soluble humic substance can in particular be extracted from natural raw materials and possibly purified by methods well known to those skilled in the art (Stevenson, 1994, Humus Chemistry, Second Edition, Wiley, New York). York). Alkaline solutions can be used to extract water-soluble humic substances from raw organic matter. These alkaline solutions can be chosen from sodium hydroxide, ammonium hydroxide, potassium hydroxide, and mixtures thereof. The alkaline solution may optionally be used in the presence of a chelating agent such as pyrophosphates, synthetic chelates (EDTA, DTPA), and others.

[0055] It is possible to prepare a suspension of the crude organic material in water and then mix it with the alkaline solution. The temperature is generally between approximately 5°C and approximately 100°C, preferably between approximately 10°C and approximately 60°C, and more preferably between approximately 20°C and approximately 40°C. Furthermore, the reaction is carried out for at least 1 minute, preferably for at least approximately 5 minutes, and preferably for at least 15 minutes.

[0056] The water-soluble humic substance can be obtained from a raw material selected from peat, leonardite, lignite, charcoal, biochar, hydrochar, urban and sewage sludge, digestates and compost.

[0057] The humic substance obtained from organic matter may be in liquid form, for example as a solution or suspension containing an insoluble organic phase and a liquid phase comprising water-soluble humic substances. The humic substance may be in solid form if the solution or suspension described above is dried.

[0058] The humic substance used in the process of the invention is preferably a humate salt, such as sodium humate or potassium humate.

[0059] According to one embodiment of the invention, the aqueous solution comprising a water-soluble phosphorus compound, a water-soluble nitrogen compound and a water-soluble humic substance is obtained by a step a) of preparing an aqueous solution comprising the water-soluble phosphorus compound and the water-soluble nitrogen compound, and a step b) of mixing the aqueous solution obtained in step a) with an aqueous solution of the water-soluble humic substance.

[0060] The aqueous solution of the water-soluble humic substance may have a pH greater than 6.5, preferably from 10.0 to 12.0.

[0061] The aqueous solution comprising the water-soluble phosphorus compound and the water-soluble nitrogen compound may have a pH between 7.0 and 9.0, preferably about 8.0. A person skilled in the art can adapt the optimal pH value according to the water-soluble phosphorus compound chosen and the water-soluble nitrogen compound chosen.

[0062] The water-soluble phosphorus compound is preferably a mineral phosphorus compound, preferably a mineral phosphate chosen from the group consisting of the acid phosphoric and its mineral salts, said mineral salts being hydrated salts or anhydrous salts.

[0063] The mineral salt of phosphoric acid includes potassium phosphate, potassium hydrogen phosphate, sodium phosphate, potassium hydrogen phosphate, monocalcium phosphate, their hydrates and mixtures thereof.

[0064] The water-soluble metallic salt is preferably a mineral metallic salt such as a metallic chloride salt, for example ferric chloride or ferrous chloride.

[0065] The water-soluble phosphorus compound is preferably chosen from the group consisting of phosphoric acid and its mineral salts, the latter being hydrated or anhydrous salts. The mineral salt of phosphoric acid may be, for example, potassium phosphate, potassium hydrogen phosphate, sodium phosphate, potassium hydrogen phosphate, their hydrates, and mixtures thereof.

[0066] The water-soluble phosphorus compound is preferably phosphoric acid.

[0067] The water-soluble nitrogen compound comprises an organic source of nitrogen, such as than urea, or a nitrogenous mineral salt, such as a mineral ammonium salt.

[0068] In a particular embodiment of the invention, the water-soluble phosphorus compound comprises a water-soluble nitrogen compound, such as ammonium phosphate or diammonium phosphate (also called ammonium hydrogen phosphate, with the formula (NH4)2HPO4). Alternatively, the water-soluble nitrogen compound may comprise a water-soluble phosphorus compound, such as ammonium phosphate or diammonium phosphate.

[0069] According to one embodiment of the manufacturing process of the invention, the water-soluble phosphorus compound comprises potassium phosphate, the nitrogen source comprises urea, the water-soluble humic substance comprises humic acid and the metallic salt is ferric chloride.

[0070] The MOF product of the invention can be used in various technical fields such as energy (storage, sensors and catalysts), biomedicine (drug delivery), the environment (gas storage, toxin removal, carbon dioxide absorption and water treatment) and agriculture (fertilizers).

[0071] According to a particular embodiment, the MOF product can be used as a fertilizer or can be incorporated into a fertilizer composition. Therefore, the present invention also relates to a method of crop fertilization that includes a step of applying an organo-metallic structural product as described above to soil and / or a crop.

[0072] In the context of this description, the term "fertilizer" means any product intended to improve plant nutrition.

[0073] In the context of the present invention, the term "plant" means the plant considered as a whole, including its root system, its vegetative system and its fruits.

[0074] The present invention is described by the following examples and experiments. Unless otherwise indicated, the temperature is between 20°C and 25°C and the pressure is 1 atm. Examples

[0075] A MOF product has been synthesized and characterized by elemental analysis, XDR, XPS, SEM, water solubility and NAC solubility. The physicochemical properties of MOF were compared to the physicochemical properties of a mixture composed of the chemical reagents (in solid form and in dry state) that were used to synthesize the MOF product. In vitro tests of phosphorus release and nitrogen protection were carried out. Furthermore, the agrochemical potential of MOF was demonstrated in an in vivo test.

[0076] Preparation of the physical mixture according to the prior art

[0077] 47 g of humic acid in KOH IM (47 g in 350 mL), a solution (ii) of KH2 PO4 (38g in 600mL) and urea (28 g / L urea), and a solution (iii) of FeCl3 (45g in 50 mL) were prepared. Preparation of the MOF material according to the invention

[0078] Humic acid extracted from leonardite (originating in the Czech Republic) was used as the organic ligand. The nitrogen source is urea and the phosphorus source is monopotassium phosphate. The metal cation is Fe(III), added as FeCl3.

[0079] To carry out the synthesis, a solution (i) of humic acid in KOH IM (47 g in 350 mL), a solution (ii) of KH2PO4 (38 g in 600 mL) and urea (28 g / L urea), and a solution (iii) of FeCl3 (45 g in 50 mL) were prepared. After mixing solutions (i) and (ii), solution (iii) was added gradually, controlling the final pH (4.20), and a precipitate was formed. A diagram of the different steps is shown in [Fig. 1]. After precipitation, the solid was centrifuged, isolated, and dried. Elementary Analysis

[0080] Elemental analysis of the precipitate obtained includes the presence of C (14.90+1.14%), which indicates the incorporation of humic acid into the MOF network. Similarly, 12.64+0.88% Fe, 15.18+1.00% K, 2.68+0.50% N and 15.91+0.71% P2O5 are detected, which shows the presence of potassium phosphate, N and Fe (metal bridge).

[0081] The EDX element maps show the distribution of nutrients in each sample. Thus, the distribution of nutrients in the MOF (see [Fig. 7]) is more higher than the distribution in the physical mixture (see [Fig.6]), which suggests their incorporation into the structure formed. Solubility

[0082] Method:

[0083] The concentrations of total phosphorus (P), zinc (Zn) and magnesium (Mg) (HCl 35%), soluble in water and soluble in neutral ammonium citrate (0.96 M; temperature of 65 °C) were analyzed according to the official analytical methods (Métodos Oficiales de Anâlisis. Tomo III; Ministerio de agricultura, pesca y alimentaciôn; Secretarîa General Técnica Ministerio de Agricultura, Pesca y Alimentaciôn: Madrid, Spain, 1994, pp 565-578). One gram of the fed sample was heated with 100 ml of water (water-P) or NAC (NAC-P) or 20 ml of 37% HCl in 100 ml of water (Total-P) for 20 minutes (25 minutes for water-P) in a hot plate, diluted to 250 ml with water, filtered and determined the P by ICP-OES.

[0084] Results:

[0085] [Table 1]

[0086] Table 1. Solubility of P in water and NAC Product % Total P2O5 % NAC P2O5 % Water P2O5 MOF 15.91+0.71 17.58+1.77 4.69+0.75

[0087] Regarding the solubility of P, it is observed that only 29.5% of the total P is soluble in water, while all of the P is soluble in neutral ammonium citrate (NAC). NAC represents the organic acids exuded by plants in the event of P deficiency. Therefore, the P soluble in NAC is higher than the P soluble in water. Consequently, the P soluble in NAC is P that is potentially available to the plant. Thus, the solubility of MOF P in water and NAC suggests high plant availability of MOF P and low fixation in the soil, resulting in reduced losses and, therefore, high fertilizer efficiency and low soil and water contamination. Amorphous structure: XRD, SEM and XPS

[0088] The X-ray diffractogram of MOF ([Fig. 3]) reveals a less crystalline appearance than that of the physical mixture (PM) ([Fig. 2]). Furthermore, crystalline phases associated with 2,4,5-trichlorophenoxyacetic acid, an organic compound with a structure analogous to that of humic acids, are observed. These two results confirm the presence and incorporation of the humic fraction in the MOF precipitate. This is consistent with the EDX results.

[0089] The SEM image of the physical mixture ([Fig.4]) shows a crystalline morphology with a predominance of KC1, while the MOF image ([Fig.5]) shows a The appearance is more amorphous with various pores embedded within the structure. This is consistent with XRD results and supports the formation of a porous structure.

[0090] Comparison of the XPS spectra of PM ([Fig.8]) and MOF ([Fig.9]) shows a different chemical environment for iron. In PM, the Fe-Cl bond can be observed, whereas in MOF, Fe is associated with oxygen. Porosity

[0091] Results:

[0092] [Table 2]

[0093] Table 2. Porosity of the MOF according to the invention and porosity of the physical mixture of chemical reagents used to prepare the MOF. Sample n Pore width B HJ (nm) Pore diameter B HJ (nm) BHJ pore volume (cm3 g1) HK pore volume (cm3 g*) MOF 7.444 4.896 0.460 0.048 PM 2.813 4.425 0.324 0.035

[0094] Higher volume, width and pore diameter are observed in the MOF compared to the physical mixture (PM), which confirms the formation of a highly porous material during the reaction with the MOF. Release of P in vitro

[0095] Dissolution Protocol:

[0096] 0.4 g were added to 40 ml of the desired medium: water, 0.96 M sodium citrate pH=4, pH=7.5, and pH=8. The mixture was stirred in a Reax2 Heidolph model at medium speed. Aliquots of the sample were taken at 5, 10, 15, 30, 50, 80, 120, and 240 minutes. Each aliquot was filtered through 0.45 µm nylon, and the pH was determined by ICP-OES.

[0097] Results:

[0098] The four curves are shown in [Fig. 10].

[0099] The kinetics of P release from MOF in different media show that approximately 30% of the total P is released into water within 80 minutes. In sodium citrate, a controlled and gradual release of the P contained in MOF is observed regardless of the pH. Theoretically, the curves show an initial zone of rapid release and a second zone of slower release. In all cases, the released MOF-P is between 70% and 100% of the total P, although there are differences in the time required for P release. Specifically, at pH 4, MOF exhibits a maximum P release of 94% at 120 minutes, while at pH 7.5, 79% is released at 1440 minutes, and at pH 8, 75% is released at 240 minutes. minutes. The greater and faster release of P at an acidic pH may be due to the acid hydrolysis of MOF. Nitrogen volatilization in soil

[0100] In order to study the behavior of the nitrogen contained in MOF, a soil incubation study was carried out to control nitrogen volatilization.

[0101] Protocol:

[0102] The volatilization model is based on that proposed by Zhepping et al (1991).

[0103] Air was circulated through a bottle of IL with water in order to obtain an atmosphere Moist soil was placed in another translucent flask containing 150 g of soil and 300 mg of N / ha. The soil was activated with 10 ml of water. Volatilized NH4+ was trapped in a 1% H3PO4 solution. NH4+ was analyzed by UV-VIS spectrophotometry using an indophenol probe-based assay. A sample was collected daily for 10 days.

[0104] Results:

[0105] Figure 11 shows a slower nitrogen loss in the presence of MOF compared to urea. Thus, the nitrogen volatilization slope from MOF is lower until day 8, where both treatments reach an asymptote.

[0106] In vivo tests to evaluate agronomic potential

[0107] To study the ability of MOF to supply P to the plant, a hydroponic trial was carried out with Arabidopsis by applying MOF and comparing it to a conventional and soluble source of P, simple superphosphate (SSP).

[0108] Protocol:

[0109] A phosphorus-free nutrient solution with the following composition was used: MgSO4, KN03, Ca(NO3)2, Fe-HBED, KCl, MnSO4, CuSO4, ZnSO4, H3BO3, and (NH4)6Mo7O24. 300 pM of phosphorus was supplied as MOF or SSP (simple superphosphate). Excess potassium was compensated with a KCl solution. The growth chamber conditions consisted of a temperature between 18°C ​​and 21°C and a humidity of 75%. Harvesting took place 10 days after phosphorus application.

[0110] Results:

[0111] The weights of the aerial part show the effectiveness of the supply of P with the MOF, obtaining results very similar to those of the application of the SSP, in both cases superior to the control without addition of P (see [Fig. 12]).

[0112] Regarding root weight, no change was observed between the control plants without P and those with SSP, but root development was greater in the plants treated with MOF. This may be due to the greater effort of the plants with MOF to mobilize the P contained in the MOF (see [Fig. 13]).

Claims

Demands

1. MOF-type organo-metallic material comprising phosphorus, nitrogen, a humic substance and at least one metal selected from iron, copper, manganese and zinc, this organo-metallic complex having a porous structure.

2. MOF-type organo-metallic material according to claim 1, wherein the average pore width of the porous structure is between 3 nm and 10 nm.

3. Organo-metallic material of type MOF according to claim 1 or claim 2, wherein a metakphosphorus molar ratio of between 1:4 and 1:1, preferably between 1:3 and 1:2, and preferably about 1:1, and / or a metal humic substance mass ratio of between 1:5 and 1:2, preferably between 1:4 and 1:2, and preferably about 1:

3.

4. A method for manufacturing an organo-metallic material of the MOF type comprising a step of preparing an aqueous solution comprising a water-soluble phosphorus compound, a water-soluble nitrogen compound and a water-soluble humic substance, a step of incorporating at least one water-soluble metallic salt of a metal selected from iron, copper, manganese and zinc, into said aqueous solution, and a step of forming a precipitate and an aqueous phase, the incorporation step being stopped when the aqueous phase has a final pH between 3.0 and 9.

0.

5. A method for manufacturing an organo-metallic material according to claim 4, wherein the preparation step and the incorporation step are carried out at atmospheric pressure and at a temperature below 100°C, preferably below 60°C, preferably still between 20°C and 30°C.

6. A method for manufacturing an organo-metallic material according to any one of claims 4 to 5, wherein the incorporation step is stopped when the aqueous phase has a final pH value between 3.5 and 7.

0.

7. A method for manufacturing an organo-metallic material according to any one of claims 4 to 6, wherein the water-soluble humic substance is a humate salt, wherein the metallic salt is ferric chloride or ferrous chloride, and wherein the water-soluble phosphorus compound is phosphoric acid.

8. A method for manufacturing an organo-metallic material according to any one of claims 4 to 7, wherein the water-soluble nitrogen compound comprises an organic nitrogen source, such as urea.

9. Method of fertilizing a plant growing on soil, said method comprising a step of applying an organo-metallic material of the MOF type according to claim 1 to the plant or to the soil.

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