Highly scalable one-pot process for synthesising zinc hydroxy salts functionalised with fatty acids

Abstract

The present invention relates to a scalable one-pot method for synthesising zinc hydroxy salts functionalised with fatty acids, based on the multiphase reaction of a zinc precursor reagent with short-, medium- or long-chain fatty acids in a protic or aprotic polar solvent.

Description

[0001] HIGHLY SCALABILITY PROCESS FOR THE SYNTHESIS OF FATTY ACID-FUNCTIONALIZED ZINC HYDROXYSALTS IN A SINGLE STEP

[0002] FIELD OF INVENTION:

[0003] The present invention describes an efficient, one-step methodology for the synthesis of zinc hydroxysalts functionalized with fatty acids, designed for industrial-scale production due to the simplicity of the process. Specifically, this disclosure relates to a continuous, semi-continuous, or batch production method for manufacturing zinc hydroxysalts functionalized with short- and long-chain fatty acids, based on a multi-phase reaction of zinc oxide and fatty acids using a polar solvent, either protic or aprotic, which allows for high process scalability.

[0004] BACKGROUND OF THE INVENTION:

[0005] Layered hydroxysalts (LHS) are characterized by having hydroxylated layers with positive electrostatic charges, stabilized by intercalated anions and held together by van der Waals and electrostatic forces (Bohari et al., 2021; Castorena-Sánchez et al., 2023; Machado Silva & Wypych, 2022; Nabipour & Hu, 2022). Both LHS and layered double hydroxides (LDH) are derived from the brucite (Mg(OH)₂) structure, but they differ in their composition and method of charge stabilization. In LDH, the substitution of divalent cations by trivalent cations generates an excess of positive charge that is neutralized by anions intercalated in the interlayer space. On the other hand, in LHS, the elimination of hydroxyl ions and their replacement by water molecules or oxoanionic anions balances the positive charge in the layers (Leal et al., 2020; Nabipour & Hu, 2022; Zhang et al., 2022). The general formula for LHS is M 2+ (OH)(2-X )(TO m “)x / m *nH2O, where M 2+ represents a divalent metallic cation and A m~ is the counteracting anion (Bohari et al., 2021; Santosa et al., 2020; Zhang et al., 2022). One specific type of LHS that has been extensively studied is the zinc hydroxysalt (Zn-LHS). The structures of Zn-LHSs containing nitrate ions in their layered region (ZHN) can be classified into two main types. Type I is associated with the empirical formula Zn₂(OH)₂(NO₃)₂*2H₂O, in which zinc is octahedrally coordinated to six hydroxyl groups, and the nitrate anions in the interlayer region are directly coordinated to the zinc. Type II, on the other hand, is subdivided into two groups based on the position of the zinc cations in the structure. In each group of type II, a quarter of the octahedral zinc cations are transferred from the main layer to tetrahedral sites located above and below the empty octahedra.In group II-a, three vertices of the tetrahedron and the apex are occupied by shared hydroxides of the octahedral sheet and water molecules, respectively. When the apex is occupied, the structure Zn5(OH)8(NO3)2*2H2O is formed, with nitrate ions surrounded by water molecules located between the layers. In group II-b, the nitrate ions occupy the apex and are directly coordinated with the tetrahedral zinc, adopting the formula Zn5(OH)8(NO3) (Nabipour & Hu, 2022; Santosa et al., 2020).

[0006] Several authors have proposed that the synthesis of Zn-LHS and the functionalization of the lamellar material with components of different natures are two distinct methodological approaches. The synthesis of Zn-LHS can be summarized in three main methodologies: hydrolysis of salts and oxides, solid-state reaction, and co-precipitation. The first synthesis methodology involves the hydrolysis of divalent metal salts using a type of metal oxide. For example, the compound Zns(OH)8(NO3)2*2H2O is obtained by the reaction between zinc oxide (ZnO) and a zinc nitrate solution (Rouba et al., 1995). Another methodology commonly used in the synthesis of zinc hydroxysalts is the solid-state reaction, which involves the reaction between appropriate amounts of hydrated zinc nitrate salt and urea under solid-state conditions to minimize the amount of water. The resulting compound is heated, washed, and filtered, respectively (Rajamathi & Kamath, 2001).Finally, the synthesis of ZHN is carried out using the coprecipitation method, which involves slowly adding a zinc nitrate solution to a stirred alkaline solution while maintaining a constant pH. This allows for the coprecipitation of the metal salt and the subsequent formation of ZHN. Generally, a heat treatment is performed to maximize yield and develop crystallinity in the sample (Cavani et al., 1991).

[0007] Layered hive hydrocarbons (LHS), and particularly zinc-plated HHS, have potential applications in various scientific and technological fields, primarily due to their ion-exchange properties. The methodological approach for the functionalization of these layered materials is based on ion exchange as an intercalation method. The direct anion exchange method aims to add various selected anions to the pre-formed ZHN layers and, consequently, exploit the interlayer anion exchange characteristics. Furthermore, other authors have proposed anion intercalation through the direct reaction between ZHN and the anion precursor acids. For example, caffeic acid has been used for the intercalation of caffeate ions in the interlayer region of ZHN (Ruiz et al., 2020).Similarly, gallate ions have been introduced into layered structures through the direct reaction between gallic acid and the hydroxyl groups present in ZnH sheets (Ruiz et al., 2019). Other authors have exchanged compounds of interest in Zn-LHS using methodologies that combine coprecipitation with ion exchange, thus developing a one-step methodology commonly referred to as the “direct method.” In this method, an anion-forming base solution is used in contact with ZnO. An alkaline solution (usually NaOH or KOH) is slowly added dropwise to the ZnO-anion mixture / dispersion until a pH close to 8.0 is reached, producing the layered structure with the anion located in the interlayer region of Zn-LHS. Components of interest exchanged in zinc sheet structures have included chlorogenic acid (Barahuie et al., 2013), salicylic acid (Adam et al., 2020; Ramli et al., 2013), cinnamic acid (Fakurazi et al., 2015; Mohsin et al., 2013), aspirin (Najem Abed et al., 2017), 3-(4-methoxyphenyl)propionic acid (Hashim et al., 2014), valeric acid (Ahmad et al., 2016), hippuric acid (S. Hussein Al Ali, Hussein, et al., 2011; SH Hussein Al Ali et al., 2013; Hussein-AI-Ali et al., 2013), protocatechuic acid (Barahuie et al., 2014), para-aminosalicylic acid (Saifullah et al., 2013), ellagic acid (Hasan Hussein-AI-Ali et al., 2013; S. Hussein Al Ali, Hussein Al Ali, et al., 2011), trans-2-hexenoic acid (Ahmad et al., 2015), cetirizine (S. Hussein Al Ali et al., 2012) and chloroacetic acid (Hashim et al., 2017).

[0008] Among other molecules studied using the direct Zn-LHS synthesis method, fatty acids, such as stearic acid and myristic acid, have been incorporated into the interlayer regions. These materials were investigated as potential fillers in polymethyl methacrylate polymers with flame-retardant properties (Nogueira et al., 2019). Other studies have employed fatty acid-functionalized laminar materials for use in various industries. Similar to the study by Nogueira et al., Jin et al. introduced stearic acid-modified Mg / Al LDH into polypropylene to increase its flame resistance (Jin et al., 2020). Likewise, Landman and Focke evaluated the impact of adding stearic acid-functionalized Mg / Al LDH on the mechanical and barrier properties of dextrin and alginate biopolymer films (Landman & Focke, 2006). Alali et al.They intercalated sodium stearate salt into layered Zn / Al double hydroxides as an antimicrobial material against Escherichia coli (Alali et al., 2022). Eshwaran et al. reinforced acrylonitrile butadiene rubber (NBR) with stearic acid-modified Zn / Al LDH (Eshwaran et al., 2015). Huang et al. applied the intercalation of 12-aminododecanoic acid and dodecanoic acid into Mg / Al LDH as a reinforcing material in ethyl vinyl acetate membranes for N2 and CO2 capture (Huang et al., 2021). Focke et al. added Mg / Al LDH with stearate ions to jojoba oil as a viscosity-reducing agent under shear stress (Focke et al., 2014). Similarly, L1 et al. They added Mg / AI / Ce LDH intercalated with lauric acid and succinic acid to engine lubricating oils as friction and wear reducing agents (L¡ et al., 2015).In another study, sodium oleate-exchanged Mg / AI LDHs were used to capture ions from ascorbic acid as drug delivery agents in the gut (Kameshima et al., 2009). Blasi et al. studied the protective effect of Mg / AI LDHs against the oxidation of long-chain fatty acids such as oleic acid, linoleic acid, and α-linolenic acid (Blasi et al., 2021). Celis et al. investigated the absorption effectiveness of pesticides (clopyralide, imazethapyr, diuron, atrazine, alachlor, and terbuthylazine) from LDHs modified with long-chain unsaturated fatty acid anions (Celis et al., 2014). In another study, Candida rugosa lipase was immobilized on sodium dioctyl sulfosuccinate-modified Zn / AI LDH to increase the stability of the enzyme in the esterification reaction between oleic acid and 1-butanol to produce hexane (Rahman et al., 2004).The application of lauric acid-modified Mg / Al LDH was also evaluated against the corrosion of magnesium alloys (Wang et al., 2020).

[0009] Based on the large number of studies reporting industrial applications of LHS and LDH-type laminar materials, several patent applications have also been published relating to LHS applications, such as drug delivery and controlled release vehicles (BR 102015002904A2), Zn-LHS as a raw material for the production of metal catalysts (US 7582202 B2), and zinc oxide nanoparticles (US 20080274041 A1). Furthermore, LHS applications have been developed in inkjet printing methods (US 6984033B2), as protective materials against surface corrosion of glassware in automatic dishwashers (CA 2542697C), and in the formulation of skin care products (EP 3423027A1 and US 20090176675A1).

[0010] Despite the wide range of applications offered by fatty acid-functionalized sheet materials, most studies report drawbacks in the scalability of the production process, both for the synthesis of these materials and for their subsequent functionalization. For example, the previously described Zn-LHS synthesis methodologies exhibit long reaction times that hinder large-scale production using continuous, semi-continuous, and batch processes. Although the acid hydrolysis methodology appears simple, stirring times between the zinc salts and ZnO of up to 24 hours have been reported (Moezzi et al., 2013), which would reduce the profitability of continuous or semi-continuous production due to the long residence times.Furthermore, subsequent functionalization of these materials by ion exchange increases the investment capital, as it requires more equipment in the process, and increases the operating time, since the residence times in ion exchange are comparable to those reported for the synthesis of the hydroxysalt. However, studies conducted on the "direct method" for the synthesis and functionalization of zinc hydroxysalts have demonstrated that this one-step methodology reduces the amount of equipment required. Additionally, the stirring times reported by the authors are approximately 8 hours, which decreases the reaction residence time. Nevertheless, to obtain a phase with high crystallinity and greater purity, an increase in the reaction temperature (70°C) is required, as well as additional reaction time due to the "aging" process of the resulting sludge.The slow dripping of alkaline solutions, with controlled pH, also requires advanced technological infrastructure, such as control systems and highly trained personnel to operate the process. These limitations hinder its application in scaling up the production process of fatty acid-functionalized sheet materials and encourage the technological development of these materials' applications to focus on laboratory-scale applications without industrial viability.

[0011] Therefore, this disclosure describes an efficient one-step method for the synthesis of Zn-LHS-type laminar materials functionalized with fatty acids. This method is based on a multi-phase reaction between the zinc precursor reagent and short- and long-chain fatty acids, using a polar solvent, which can be either protic or aprotic. This methodology is designed to be industrially scalable due to its simplicity, high crystallinity, low energy consumption, relatively short residence times, and overall process ease. The synthesis of Zn-LHS functionalized with fatty acids can be carried out continuously, semi-continuously, or in batches, taking advantage of the chemical affinity of the functionalized laminar materials for the solvent used.

[0012] SUMMARY OF THE INVENTION:

[0013] This disclosure describes a continuous, semi-continuous, or batch process for manufacturing a zinc nanostructured sheet material functionalized with short- and long-chain fatty acids. The disclosed method typically comprises dispersing zinc oxide in a mixture of the polar solvent and the fatty acid. The resulting mixture contains the zinc hydroxysalt functionalized with the fatty acid. The scalable procedure of this method involves the following steps: a) Dispersal of zinc oxide: Zinc oxide is dispersed in a polar solvent, which may be protic or aprotic, using a reactor, either a stirred kettle or a continuous stirred tank reactor (CSTR). b) Addition of fatty acid: The fatty acid, whether short-, medium-, or long-chain, is added to reach the reaction volume. c) Phase separation: After the residence time in the reactor, the mixture is separated by filtration or centrifugation.d) Solvent recirculation: The liquid phase, containing the solvent and traces of fatty acid, is recirculated to the stirring tank to reduce raw material costs. e) Solid drying: The resulting solid is transferred to a drying unit to obtain the zinc hydroxysalt functionalized with the required fatty acid. f) Product milling: The resulting solid is transferred to a milling unit to obtain the product with the desired particle size distribution.

[0014] The present invention enables the efficient and scalable one-step production of fatty acid-functionalized zinc hydroxysalts, optimizing material and energy use in the process. These hydroxysalts are characterized by their use in the encapsulation and protection of bioactive compounds and biomolecules, the controlled release of drugs, the adsorption of contaminants present in wastewater, and their incorporation into polymeric and biopolymeric matrices to improve the mechanical, thermal, and barrier properties of composite materials. These applications highlight the versatility of hydroxysalts and their broad potential in diverse industries, ranging from chemicals, pharmaceuticals, and dermocosmetics to environmental and advanced materials.

[0015] BRIEF DESCRIPTION OF THE FIGURES:

[0016] The accompanying figures are incorporated herein and form part of this disclosure.

[0017] Figure 1 shows a schematic of a system for the continuous production of a nanostructured sheet material of the type zinc hydroxysalts functionalized with fatty acids.

[0018] Figure 2 shows the X-ray diffraction pattern for pure ZnO.

[0019] Figure 3 shows the effect of the ratio of reactants (short chain fatty acid (caprylic acid; AC) and ZnO) on the crystal structure of Zn-LHS formed using water as the reaction solvent.

[0020] Figure 4 shows the effect of the reagent ratio (short chain fatty acid (SCA) and ZnO) on the Zn-LHS crystal structure formed using acetone as the reaction solvent.

[0021] Figure 5 shows the effect of the solvent (acetone, water or ethanol) on the Zn-LHS functional groups formed from AC and ZnO by infrared spectroscopy.

[0022] Figure 6 shows the effect of the solvent (acetone, water or ethanol) on the morphology of Zn-LHS formed from AC and ZnO by scanning electron microscopy, with Figures 6a and 6b being the micrographs of Zn-LHS obtained with acetone, Figures 6c and 6d with water, and Figures 6e and 6f with ethanol.

[0023] Figure 7 shows the effect of the ratio of reactants (long chain fatty acid (oleic acid; AO) and ZnO) on the crystal structure of Zn-LHS formed using water as the reaction solvent.

[0024] Figure 8 shows the effect of the ratio of reactants (long chain fatty acid (OA) and ZnO) on the crystal structure of Zn-LHS formed using acetone as the reaction solvent.

[0025] Figure 9 shows the effect of the solvent (acetone, water or ethanol) on the Zn-LHS functional groups formed from AO and ZnO by infrared spectroscopy.

[0026] Figure 10 shows the effect of the solvent (acetone, water or ethanol) on the morphology of Zn-LHS formed from AO and ZnO by scanning electron microscopy, with Figures 10a and 10b being the micrographs of Zn-LHS obtained with acetone, Figures 10c and 10d with water and Figures 10e and 10f with ethanol.

[0027] DETAILED DESCRIPTION OF THE INVENTION:

[0028] Definitions:

[0029] Although the specification of the present invention concludes with the claims that specifically address and clearly assert the invention, it is believed that the present invention will be better understood from the following description of the terms or phrases used in this disclosure.

[0030] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by persons skilled in the subject matter to which this description refers. Any limitation on the defined terms shall not be understood to invalidate the other meanings that comprise a definition in other contexts. The phrase "functional group" is defined as any chemical group or atom that provides a specific behavior.

[0031] The term "functionalized" is defined as the addition of a functional group or groups to layered materials, specifically in the interlayer region of Zn-LHS.

[0032] The term "nanostructure" refers to a structure or material that has components that have at least one dimension that is 100 nm or smaller.

[0033] The phrase "nanostructured material" refers to a material whose components have an arrangement that has at least a characteristic length scale of 100 nanometers or less.

[0034] A "continuous process" refers to a production process in which material flows (quantities of material over a given time) are managed. In this type of process, raw materials are introduced continuously, and specific residence times are established for each stage of the process, thus achieving a constant flow of product.

[0035] A "batch process" is a process in which a fixed quantity of raw material is introduced into a closed system, and after a predetermined time, the product is obtained. This type of process is characterized by its operation in discrete stages, where each production batch is treated as an individual entity from the beginning to the end of the production cycle.

[0036] A "semi-continuous process" refers to a production process that combines characteristics of both continuous and batch processes. In this type of process, raw materials are introduced at regular intervals or in specific quantities, allowing some stages to operate continuously while others are stopped and restarted in defined cycles.

[0037] Synthesis process of Zn-LHS functionalized with fatty acids:

[0038] In the first instance, the present invention relates to a one-step method for synthesizing Zn-LHS functionalized with fatty acids. The method described above includes the reaction step (dispersion of the zinc precursor reagent in the solvent and its subsequent reaction with the added fatty acid) of the system.

[0039] To achieve high purity in Zn-LHS functionalized with fatty acids, it is essential to use raw materials with minimal impurities and minimize processes susceptible to contamination. However, if the cost of raw materials increases when using high-purity materials, the cost of the functionalized material will also increase, hindering its market expansion for the various applications described in this invention.

[0040] Based on these raw material conditions, the production process, outlined in Figure 1, consists of a continuous two-stage process. The method described in the present invention can be modified according to the scale and type of process required. If a batch process is desired, the flows are changed by discharging the raw materials, eliminating the need for pumps and a conveyor belt.

[0041] At the start of the process, a centrifugal pump (6) feeds the solvent (5) into the reaction tank (8). Subsequently, the zinc precursor reagent (1) is introduced into the reaction tank (8) via a conveyor belt (2). An agitator (7) maintains the dispersion of the zinc precursor reagent in the solvent under constant stirring. The fatty acid (3) is added to the resulting mixture in the reaction tank (8) using a centrifugal pump (4). After the reaction time has elapsed, the reaction mixture (10) is conveyed to a separation unit (11) by a centrifugal pump (9). In the separation unit, the partially moistened, lamellar material is obtained in stream (13), while the solvent containing traces of fatty acid is recirculated (12) to the reaction tank (8).The sludge containing functionalized Zn-LHS is dried in a drying unit (14), yielding a stream with the dry product (15) and a steam stream resulting from dehumidification (16). Finally, the dried solid is passed through a grinding unit (17) that adjusts the particle size of the product (18) according to the required application.

[0042] In one embodiment of the invention, the zinc precursor reagent is zinc oxide (ZnO), with a purity greater than 70%. In another embodiment of the invention, the zinc precursor reagent may be zinc hydroxide (Zn(OH)2), with a purity greater than 70%. In another embodiment of the invention, the zinc (Zn) precursor reagent may be Zn-LHS obtained from synthesis methods such as hydrolysis of salts and oxides, solid-state reaction, and coprecipitation, containing anions in their interlayer region such as chloride (Cl₂), nitrate (NO₃⁻), and sulfate (SO₄²⁻). 2 ), carbonate (CO3 2 ), phosphate (PO43 ), fluoride (F ), bromide (Br ), iodide (I ), perchlorate (ClO4 ), tetraborate (B4O7 ), fluoride (F ), bromide (Br ), bromide (Br ), iodide (I ), perchlorate (ClO4 ), tetraborate (B4O7 ), perchlorate ... 2 ), dichromate (Cr2O7 2 ), silicate (SiO4 4- , HSiO?-, S¡O3 2 ), manganate (MnO4 2 ), permanganate (MnO4), thiosulfate (S2O3 2 ), acetate (CH3COO), oxalate (C2O4 2 ), tartrate (C4H4Oe 2 ), citrate (C6H5O7 3 ), lactate (C3H5O3), formate (HCOO) or malonate (C3H2O4 2 ). In a preferred embodiment of the invention, the zinc precursor reagent is zinc oxide (ZnO) with a high degree of purity.

[0043] In one embodiment of the invention, the solvent is a protic polar solvent such as water (H2O), methanol (CH3OH), ethanol (C2H5OH), propanol (C3H7OH), isopropanol (C3H7OH), n-butanol (C4H9OH), isobutanol (C4H9OH), t-butanol (C4H9OH), formamide (HCONH2) or mixtures thereof. In another embodiment of the invention, the solvent is a polar aprotic solvent such as dimethyl sulfoxide (DMSO) (C2H6OS), n,n-dimethylformamide (DMF) (C3H7NO), acetonitrile (CH3CN), acetone (C3H6O), tetrahydrofuran (THF) (C4H8O), dioxane (C4H8O2), tetramethylene sulfoxide (TMS) (C4H10OS), methyl ethyl ketone (MEK) (C4H8O), propylene carbonate (C4H6O3), ethylene carbonate (C3H4O3), nitromethane (CH3NO2) or mixtures thereof.

[0044] In one embodiment of the invention, the fatty acid is short-chain selected from butyric acid (butanoic acid, C3H7COOH), isobutyric acid (2-methylpropanoic acid, (CH3)2CHCOOH), valeric acid (pentanoic acid, C4H9COOH), isovaleric acid (3-methylbutanoic acid, (CH3)2CHCH2COOH), 2-methylbutanoic acid (CH3CH2CH(CH3)COOH), caproic acid (hexanoic acid, C5H11COOH), 2-methylpentanoic acid (CH8CH2CH2CH(CH3)COOH), 3-methylpentanoic acid (CH3CH2CH(CH3)CH2COOH), 2,2-dimethylbutanoic acid ((CH3)3CCH2COOH), 2,3-dimethylbutanoic acid ((CH3)2CHCH(CH3)COOH) or mixtures thereof. In another embodiment of the invention, the fatty acid is medium-chain selected from enantic acid (heptanoic acid, C7H15COOH), caprylic acid (octanoic acid, C7H15COOH), pelargonic acid (nonanoic acid, C8H17COOH), capric acid (decanoic acid, C9H19COOH), undecanoic acid (C10H21COOH), lauric acid (dodecanoic acid, C11H23COOH) or mixtures thereof.In a further embodiment of the invention, the fatty acid is a long-chain acid selected from myristic acid (tetradecanoic acid, C13H27COOH), pentadecanoic acid (C14H29COOH), palmitic acid (hexadecanoic acid, C15H31COOH), margaric acid (heptadecanoic acid, C16H33COOH), stearic acid (octadecanoic acid, C17H35COOH), nonadecanoic acid (C18H87COOH), arachidic acid (eicosanoic acid, C19H39COOH), heneicosanoic acid (C20H41COOH), palmitoleic acid (9-hexadecenoic acid, C16H30O2), oleic acid (9-octadecenoic acid, C18H34O2), eicosenoic acid (11-eicosenoic acid, C20H38O2), linoleic acid (11-eicosanoic acid, C20H38O2), linoleic acid (11-eicosanoic acid, C20H38O2), and linoleic acid (11-eicosanoic acid, C20H38O2). 9,12-octadecadienoic acid, CI8H32O2), α-linolenic acid (9,12,15-octadecatrienoic acid, CI8H8O02), arachidonic acid (5,8,11,14-eicosatetraenoic acid, C20H32O2), eicosapentaenoic acid (EPA, 5,8,11,14,17-eicosapentaenoic acid, C20H30O2), docosahexaenoic acid (DHA, 4,7,10,13,16,19-docosahexaenoic acid, C22H34O2) or mixtures thereof.In a preferred embodiment of the invention, the fatty acids are caprylic acid and oleic acid with a purity ranging from food grade (approximately 60%) to reagent grade (>90%).

[0045] In one embodiment of the invention, the reaction tank is selected from a stirred kettle for a batch process or a CSTR reactor for a semi-continuous or continuous process. The reaction tanks may be jacketed for temperature control. The agitators used in the reaction tanks are selected from an axial propeller agitator, radial propeller agitator, flat paddle agitator, anchor agitator, turbine agitator, inclined paddle agitator, helical ribbon propeller agitator, Rushton-type agitator (disc turbine with paddles), baffle or dance agitator, inclined or adjustable-angle paddle agitator, gas-injected propeller agitator, cowles-type agitator, inclined turbine or high-profile axial-flow agitator, double-helix agitator, or magnetic agitator. In a preferred embodiment, the reaction tank is a kettle with an anchor agitator.

[0046] In one embodiment of the invention, the pump is selected from a stainless steel centrifugal pump, diaphragm pump (pneumatic or electric), peristaltic pump, external gear pump, eccentric screw pump, lobe pump, Teflon-lined centrifugal pump, pneumatic piston pump, positive displacement (rotary) pump, internal gear pump, double-acting diaphragm pump, magnetic pump, progressive cavity pump, vane pump, or pneumatic double-diaphragm pump. In another embodiment of the invention, the pump is selected from a centrifugal pump positioned horizontally, vertically, or at an angle. In a preferred embodiment, the pump employed is a stainless steel centrifugal pump.

[0047] In one embodiment of the invention, the separation equipment is a filter selected from a cartridge filter, bag filter, plate and frame filter, disc filter, portable pressure filter, filter press, centrifugal disc filter, rotary drum filter, deep bed filter, filter belt filter, continuous vacuum drum filter, decanter centrifugal filter, or rotary vacuum filter. In another embodiment of the invention, the separation equipment is a decanter centrifuge selected from a decanter centrifuge, disc centrifuge, tubular centrifuge, perforated basket centrifuge, solid drum centrifuge, continuous flow centrifuge, sedimentation centrifuge, plate centrifuge, fixed bed centrifuge, high-speed centrifuge, solid rotor centrifuge, self-discharging vertical centrifuge, ultracentrifugation centrifuge, rotary drum centrifuge, or continuous drum centrifuge.In a preferred embodiment, the separation system comprises a decanter centrifuge or a filter press.

[0048] In one embodiment of the invention, the drying equipment is a fluidized bed dryer, tray dryer, rotary drum dryer, spray dryer, vacuum dryer, conveyor belt dryer, infrared dryer, flash dryer, tunnel dryer, sliding bed dryer, microwave dryer, cylinder dryer, rotary vacuum dryer, hot air dryer, or freeze dryer (lyophilizer). In a preferred embodiment, the drying equipment is a tray dryer or a conveyor belt dryer.

[0049] In one embodiment of the invention, the grinding equipment is selected from a blade mill, hammer mill, ball mill, roller mill, disc mill, rotor mill, micron mill, ultrafine grinding mill, crusher mill, or centrifugal mill. In a preferred embodiment, the grinding equipment is a ball mill.

[0050] In one embodiment of the invention, approximately 0.001 to 0.01 moles of zinc precursor reagent, approximately 0.0025 to 0.02 moles of fatty acid, and 10 to 100 mL of solvent are used. In a preferred embodiment of the invention, approximately 0.001 moles of zinc precursor reagent, approximately 0.001 moles of fatty acid, and approximately 10 mL of solvent are used. In a further preferred embodiment, approximately 0.005 moles of zinc precursor reagent, approximately 0.01 moles of fatty acid, and approximately 50 mL of solvent are used.

[0051] In one embodiment of the invention, the reaction volume used is between approximately 10 mL and approximately 10,000 L. In a preferred embodiment of the invention, the reaction volume used is between approximately 10 mL and approximately 500 L. In another preferred embodiment of the invention, the reaction volume used is between approximately 20 mL and approximately 50 L. In yet another preferred embodiment of the invention, the reaction volume used is between approximately 50 mL and approximately 1 L. In a further preferred embodiment of the invention, the reaction volume used is between approximately 80 mL and approximately 500 mL. In a still more preferred embodiment of the invention, the reaction volume used is approximately 100 mL.

[0052] In one embodiment of the invention, the suspension is stirred at approximately 200 to 600 rpm and at a temperature of approximately 18 to 25 °C. In a preferred embodiment of the invention, the suspension is stirred at approximately 400 rpm and at a temperature of approximately 20 °C.

[0053] In one embodiment of the invention, the residence time in the reaction tank is between approximately 10 minutes and approximately 24 hours. In a preferred embodiment of the invention, the residence time in the reaction tank is approximately 180 minutes. In a further preferred embodiment, the residence time in the reaction tank is approximately 12 hours.

[0054] The present invention will now be described specifically based on examples.

[0055] EXAMPLES:

[0056] Example 1: Synthesis of caprylic acid (AC) functionalized Zn-LHS using water as solvent

[0057] For the synthesis of AC-functionalized Zn-LHS, 0.0050 moles of ZnO were prepared as a zinc precursor reagent in 50 mL of water as the solvent in a magnetically stirred reactor. The resulting suspension was mechanically stirred at 400 rpm. Then, 0.0025, 0.0050, and 0.0100 moles of AC were added to three different mixtures under constant stirring. The reaction was carried out for 24 hours at room temperature, maintaining a constant stirring speed.

[0058] At the end of the reaction time, the mixture was vacuum filtered and the supernatant was separated. The resulting precipitate was washed with deionized water and dried in an electric oven at 50°C for 24 hours. The resulting white precipitate weighed 1.432, 2.190, and 3.546 g for the 1:2, 1:1, and 2:1 AC:ZnO ratios, respectively, and was analyzed by X-ray diffraction (using CuKa rays). The comparative diffraction pattern of the synthesized samples, shown in Figure 3, confirmed the presence of a phase characteristic of the layered materials, represented by four harmonics located at 20.1, 10.3, 6.9, and 5.2 Å.

[0059] The study showed that a 1:2 ZnO to AC molar ratio produced a purer lamellar phase compared to the other molar ratios evaluated. This was evidenced by the disappearance of the diffraction peaks associated with ZnO, as shown in Figure 2.

[0060] Example 2: Synthesis of caprylic acid (AC) functionalized Zn-LHS using acetone as solvent

[0061] For the synthesis of AC-functionalized Zn-LHS, 0.0050 moles of ZnO were prepared as a zinc precursor reagent in 50 mL of acetone as solvent in a magnetically stirred reactor. The resulting suspension was mechanically stirred at 400 rpm. Then, 0.0025, 0.0050, and 0.0100 moles of AC were added to three different mixtures under constant stirring. The reaction was carried out for 24 hours at room temperature, maintaining a constant stirring speed. At the end of the reaction time, the mixture was vacuum filtered, and the supernatant was separated. The resulting precipitate was washed with deionized water and dried in an electric oven at 50°C for 24 hours. The resulting white precipitate was 1.377, 2.129 and 3.369 g for the 1:2, 1:1 and 2:1 AC:ZnO ratios, respectively, and was analyzed by X-ray diffraction (using CuKa rays).The comparative diffraction pattern of the synthesized samples, shown in Figure 4, confirmed the presence of a characteristic phase of the layered materials represented by four harmonics located at 20.9, 10.4, 6.9 and 5.2 Å.

[0062] The study showed that a 1:2 ZnO to AC molar ratio produced a purer lamellar phase compared to the other molar ratios evaluated. This was evidenced by the disappearance of the diffraction peaks associated with ZnO, as shown in Figure 2.

[0063] Example 3: Comparison between the solvents used in the synthesis of Zn-LHS functionalized with idocaprylic acid (AC)

[0064] For the synthesis of AC-functionalized Zn-LHS, 0.0050 moles of ZnO were placed in 50 mL of solvent, such as acetone, water, and ethanol, in a magnetically stirred reactor. The resulting suspension was mechanically stirred at 400 rpm. Then, 0.0100 moles of AC were added to three different mixtures under constant stirring. The reaction was carried out for 24 hours at room temperature, maintaining a constant stirring speed. At the end of the reaction time, the mixture was vacuum filtered, and the supernatant was separated. The resulting precipitate was washed with deionized water and dried in an electric oven at 50°C for 24 hours. The precipitates were analyzed by infrared spectroscopy, and the results are presented in Figure 5.

[0065] In the comparative FTIR spectrum of the zinc hydroxysalt with caprylic acid, several characteristic bands are observed, associated with the functional groups of caprylate (the ionized form of caprylic acid) and their interactions with zinc. The bands at 2956, 2921, 2868, and 2849 cm⁻¹ -1 These correspond to the asymmetric and symmetric stretching of the CH bonds in the methyl and methylene groups of the caprylate aliphatic chain. The band at 1592 cm⁻¹ -1 is related to the asymmetric stretching of the carboxylate group (COO), while the 1524 cm -1 This represents the symmetrical stretching of the same group. The bands are at 1452 and 1346 cm. -1 are associated with bending in the CH plane in the methyl and methylene groups, while those of 1396, 1308, 1260, 1214, 1118, 1066, 1044 and 1028 cm' 1These correspond to the stretching of the CO bond in the carboxylate group, with slight variations in intensity and position due to coordination with zinc. In the lower wavenumber bands, those at 949, 912, 890, and 833 cm⁻¹ 1 The bands at 771, 744, and 721 cm⁻¹ indicate out-of-plane CH bends in the aliphatic chain of caprylate. -1 They are related to flexions of the COO- group. Finally, the bands at 580 and 551 cm -1 These represent the Zn-O stretching patterns, characteristic of the hydroxysalt crystal lattice, affected by the presence of hydroxyl and carboxylate groups. Finally, Figure 5 shows no significant differences between the vibrational bands of the zinc hydroxysalts functionalized with caprylic acid using different solvents.

[0066] However, Figure 6 shows differences in the morphologies of the materials formed depending on the solvent used, as observed by scanning electron microscopy (SEM). Figures 6a and 6b show SEM micrographs of zinc hydroxysalts functionalized with caprylate using acetone as the solvent. These images reveal that the sample has an aggregated structure of sheets or plates with irregular surfaces and scattered edges. These sheets appear to stack or cluster, creating a more defined structure with variations in thickness and size. The measurements shown indicate that the individual sheets have dimensions ranging from approximately 400 nm to 1.2 pm.

[0067] Regarding water as a solvent, Figures 6c and 6d show that the caprylate-functionalized zinc hydroxysalts exhibit considerable agglomeration, hindering the visualization of well-defined lamellar structures and leading to the formation of compact aggregates. Despite this agglomeration, the sheets are not amorphous; they maintain an organized structure with clear edges and smooth surfaces. Measurements show that individual sheets have thicknesses (z-axis) varying between 130 nm and 240 nm, suggesting a dense and compact arrangement of the material in the nanometric range.

[0068] On the other hand, Figures 6e and 6f show micrographs of zinc hydroxysalts functionalized with caprylate using ethanol as a solvent. These images reveal a lamellar structure composed of particles resembling relatively well-defined plates or sheets. Unlike the previous sample, this micrograph shows less agglomeration, allowing individual particles to be distinguished more clearly. The sheets are less compact and more dispersed compared to the previous sample, suggesting that the change in solvent affected the organization and degree of agglomeration of the material. The individual particles show defined edges and appear to have a more random orientation, forming a loosely layered structure.The particles exhibit variable thickness, with measurements ranging from approximately 97 nm to 422 nm, confirming the nanometric nature of the material along the z-axis. The sheets are elongated and show well-defined edges, indicating a crystalline structure. Despite the relative dispersion of the sheets, some points of contact and aggregation are observed, suggesting that the structure remains lamellar, but with a less compact arrangement than in previous SEM micrographs of the sample with other solvents.

[0069] Example 4: Synthesis of Zn-LHS functionalized with oleic acid (AO) using water as a solvent

[0070] For the synthesis of AO-functionalized Zn-LHS, 0.0050 moles of ZnO were placed in 50 mL of water as the solvent in a magnetically stirred reactor. The resulting suspension was mechanically stirred at 400 rpm. Then, 0.0025, 0.0050, and 0.0100 moles of AO were added to three different mixtures under constant stirring. The reaction was carried out for 24 hours at room temperature, maintaining a constant stirring speed.

[0071] At the end of the reaction time, the mixture was vacuum filtered and the supernatant separated. The resulting precipitate was washed with deionized water and dried in an electric oven at 50°C for 24 hours. The resulting white precipitate weighed 10.229, 14.800, and 19.546 g for the 1:2, 1:1, and 2:1 AO:ZnO ratios, respectively, and was analyzed by X-ray diffraction (using CuKa rays). The comparative diffraction pattern of the synthesized samples, shown in Figure 7, confirmed the presence of a phase characteristic of the layered materials, represented by seven harmonics located at 42.0, 20.9, 14.1, 10.5, 8.5, 7.1, and 6.1 Å.

[0072] The study showed that a 1:2 ZnO to AO molar ratio produced a purer lamellar phase compared to the other molar ratios evaluated. This was evidenced by the disappearance of the diffraction peaks associated with ZnO, as shown in Figure 2.

[0073] Example 5: Synthesis of Zn-LHS functionalized with oleic acid (AO) using acetone as solvent

[0074] For the synthesis of AO-functionalized Zn-LHS, 0.0500 mol of ZnO was placed in 50 mL of acetone as the solvent in a magnetically stirred reactor. The resulting suspension was mechanically stirred at 400 rpm. Then, 0.0250, 0.0500, and 0.1000 mol of AO were added to three different mixtures under constant stirring. The reaction was carried out for 24 hours at room temperature, maintaining a constant stirring speed.

[0075] At the end of the reaction time, the mixture was vacuum filtered and the supernatant was separated. The resulting precipitate was washed with deionized water and dried in an electric oven at 50°C for 24 hours. The resulting white precipitate weighed 2.137, 3.336, and 4.189 g for the 1:2, 1:1, and 2:1 AO:ZnO ratios, respectively, and was analyzed by X-ray diffraction (using CuKa rays). The comparative diffraction pattern of the synthesized samples, shown in Figure 8, reveals the presence of a phase characteristic of the layered materials, represented by seven harmonics located at 42.0, 20.9, 14.1, 10.5, 8.5, 7.1, and 6.1 Å.

[0076] The study showed that a 1:2 ZnO to AO molar ratio produced a purer lamellar phase compared to the other molar ratios evaluated. This was evidenced by the disappearance of the diffraction peaks associated with ZnO, as shown in Figure 2.

[0077] Example 6: Comparison between the solvents used in the synthesis of Zn-LHS functionalized with oleic acid (AO)

[0078] For the synthesis of AO-functionalized Zn-LHS, 0.0050 moles of ZnO were placed in 50 mL of solvent, such as acetone, water, and ethanol, in a magnetically stirred reactor. The resulting suspension was mechanically stirred at 400 rpm. Then, 0.0100 moles of AO were added to three different mixtures under constant stirring. The reaction was carried out for 24 hours at room temperature, maintaining a constant stirring speed. At the end of the reaction time, the mixture was vacuum filtered, and the supernatant was separated. The resulting precipitate was washed with deionized water and dried in an electric oven at 50°C for 24 hours. The precipitates obtained were analyzed by infrared spectroscopy and are shown in Figure 9.

[0079] In the FTIR spectrum of the zinc hydroxysalt with oleic acid, several characteristic bands are observed, associated with the functional groups of the oleate (ionized form of oleic acid) and its interaction with zinc. The bands at 3368 cm⁻¹ -1 These bands are associated with OH stretching vibrations, probably originating from water molecules or hydroxyl groups. The bands are located at 3002, 2954, 2918, and 2849 cm⁻¹. 1 These correspond to the asymmetric and symmetric stretching of the CH bonds in the methyl and methylene groups of the oleate aliphatic chain. The band at 1589 cm⁻¹ -1 is related to the asymmetric stretching of the carboxylate group (COO“), while the bands at 1545 and 1524 cm’ 1 They represent the symmetrical stretching of the same group, indicating the coordination of the carboxylate with zinc. Furthermore, the bands at 1453 and 1398 cm⁻¹ 1They are associated with bending in the CH plane of the methyl and methylene groups, while the bands at 1348, 1319 and 1280 cm -1 These bands are attributed to stretching of the CO bond in the carboxylate group, slightly affected in intensity and position by the interaction with zinc. Additional bands at 1240, 1199, 1094, and 1046 cnr 1 They also reflect CO stretches, contributing to the characterization of the complex. In the lower wavenumber range, the bands at 949, 828, 743, and 722 cm⁻¹ are also present. -1 They indicate out-of-plane CH bends in the aliphatic oleate chain, while the band at 534 cm -1This represents the Zn-O stretching, characteristic of the zinc hydroxysalt crystal structure, which is influenced by the presence of carboxylate and hydroxyl groups. Finally, in Figure 9, no significant differences are observed between the vibrational bands of the zinc hydroxysalts functionalized with oleic acid using different solvents.

[0080] However, the scanning electron microscopy (SEM) results, presented in Figure 10, suggest that the solvent significantly affects the morphology of the resulting materials. With acetone as the solvent (Figures 10a and 10b), a predominantly layered structure is observed, characteristic of lamellar materials with an overlapping layer arrangement. Considerable agglomeration of the lamellae is evident, forming dense, compact aggregates that obscure the definition of each lamella. In the center of the image, a formation of agglomerated particles with an irregular morphology is observed, promoting structural heterogeneity within the lamellar matrix. The lamellae exhibit irregular edges and a morphology that suggests fragmentation or partial exfoliation, possibly as a result of interaction with the oleate in an acetone medium.This morphology could be indicative of the formation of bonding sites between the oleate and the zinc sheets, which generates variability in the structure due to Van der Waals forces and the insertion of the oleate into the lamellar matrix. Size measurements highlight the thickness of the sheets, which varies between approximately 31.72 nm and 107.1 nm, indicating a heterogeneous thickness distribution of these layers within the nanometer range.

[0081] On the other hand, SEM micrographs of zinc hydroxysalts functionalized with oleic acid using water as a solvent are shown in Figures 10c and 10d. The sheets exhibit greater cohesion, forming a more compact layered structure, which could be attributed to the effect of water as a solvent, promoting stronger interactions between the zinc hydroxysalt layers. This cohesion likely limits the separation and exfoliation observed in more organic solvents, resulting in a more uniform and stable lamellar arrangement. The edges of the sheets appear less irregular, with a more homogeneous particle size. Measurements indicate sheet thicknesses ranging from approximately 64.73 nm to 118.9 nm, suggesting a more robust and less fragmented structure.

[0082] Finally, the morphology of the zinc hydroxysalts functionalized with oleic acid using ethanol as a solvent is shown in Figures 10e and 10f. In this SEM micrograph of the zinc hydroxysalt with oleate synthesized using ethanol as a solvent, a granular and highly agglomerated morphology is observed, in contrast to the lamellar structures seen with other solvents. Measurements indicate particle sizes in the range of approximately 100.7 nm to 379.3 nm, confirming the formation of nanometer-sized particles with a considerably broad size distribution. This behavior suggests that ethanol promotes rapid nucleation followed by limited growth, resulting in small particles and a dense, agglomerated structure.The morphology of these particles is irregular and tends toward the formation of compact clusters, suggesting that ethanol facilitates strong interactions between the particles, possibly through hydrogen bonds or Van der Waals interactions. The lack of well-defined lamellar structures, observed in solvents such as water or acetone, indicates that ethanol modifies the aggregation dynamics of the zinc hydroxysalt layers, promoting a more chaotic and less organized three-dimensional configuration.

[0083] The examples above show that a zinc precursor to fatty acid molar ratio of 1:2 yields the best results for obtaining a clean phase of the hydroxysalt, as verified by X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). By varying the formulation composition, the material can be produced as a low-viscosity liquid, a high-viscosity liquid, or a solid, offering the potential user greater flexibility to meet market or industry needs.

[0084] This flexibility in composition is achieved by varying the ratio of the zinc precursor to mixed fatty acids, as well as the concentration of the raw materials in the reaction volume, the type of acid, and the solvent used. For example, selecting solid fatty acids, such as stearic acid, can produce solid products with adipose characteristics. Similarly, selecting a liquid mixture of fatty acids, such as oleic acid, can produce a liquid product. However, using water as the solvent and increasing the concentration of the reactants involved in the reaction—ZnO and oleic acid—results in a hydrophobic solid. Furthermore, changing the solvent from protic to aprotic yields solid products with traces of fatty acid, giving them an adipose characteristic.

Claims

CLAIMS 1. A one-step method for synthesizing Zn-LHS functionalized with fatty acids, comprising: a. Dispersing the zinc precursor reagent in a polar protic or aprotic solvent in a reactor, wherein the reactor is a stirred kettle or a continuous stirred tank (CSTR); b. Adding the fatty acid to complete the reaction volume, wherein the fatty acid is short-chain or long-chain; c. Separating the mixture after the residence time in the reactor, wherein the separation is by filtration or centrifugation; d. Recirculating the liquid phase to the stirred tank, wherein the liquid phase consists of the solvent and traces of fatty acid; e. Drying the solid obtained from step (d) in drying equipment; and f. Milling the zinc hydroxysalt functionalized with the required fatty acid from step (e) in milling equipment.

2. The method of claim 1, wherein the zinc (Zn) precursor reagent is selected from: a. ZnO with a wide range of purity, usually greater than 70%; b. Zn(OH)2, with a wide range of purity, usually greater than 70%; or c. Zn-LHS obtained from hydrolysis of salts and oxides, solid-state reaction and coprecipitation, containing anions in their interlayer region such as chloride (Cl), nitrate (NO3), sulfate (SO4). 2 ), carbonate (CO3 2 ), phosphate (PO4 3 ), fluoride (F ), bromide (Br ), iodide (I ), perchlorate (ClO4 ), tetraborate (B4O7 ), fluoride (F ), bromide (Br ), bromide (Br ), iodide (I ), perchlorate (ClO4 ), tetraborate (B4O7 ), perchlorate ... 2 ), dichromate (Cr2O7 2 ), silicate (SiO4 4- , HSI04 3- , S¡O3 2 ), manganate (MnO4 2 ), permanganate (MnO4), thiosulfate (S2O3 2 ), acetate (CH3COO), oxalate (C2O4 2- ), tartrate (C4H4O6 2 ), citrate (C6H5O7 3 ), lactate (C3H5O3), formate (HCOO) or malonate (C3H2O4 2 ).

3. The method of claim 1, wherein the polar solvent is: a. A protic solvent selected from water (H2O), methanol (CH3OH), ethanol (C2H5OH), propanol (C3H7OH), isopropanol (C3H7OH), n-butanol (C4H9OH), isobutanol (C4H9OH), t-butanol (C4H9OH), formamide (HCONH2) or mixtures thereof; b. An aprotic solvent selected from dimethyl sulfoxide (DMSO) (C2H6OS), n,n-dimethylformamide (DMF) (C3H7NO), acetonitrile (CH3CN), acetone (C3H6O), tetrahydrofuran (THF) (C4H8O), dioxane (C4H8O2), tetramethylene sulfoxide (TMS) (C4HWOS), methyl ethyl ketone (MEK) (C4H8O), propylene carbonate (C4H6O3), ethylene carbonate (C3I-O3), nitromethane (CH3NO2) or mixtures thereof.

4. The method of claim 1, wherein the dispersion of the zinc precursor reagent in the solvent can employ reaction volumes from 10 mL to 10,000 L.

5. The method of claim 1, in which the zinc precursor reagent is dispersed in the solvent, can have residence times from 10 seconds to 30 min.

6. The method of claim 1, in which the production process of Zn-LHS functionalized with fatty acids is described, comprises batch, semi-continuous or continuous processes.

7. The method of claim 1, wherein the dispersion of the zinc precursor and the reaction with the fatty acid comprises concentrations of the reactants between 1x10 -5 mol and 10,000 mol.

8. The method of claim 1, wherein the fatty acids are selected from: a. Short-chain fatty acids selected from butyric acid (butanoic acid, C3H7COOH), isobutyric acid (2-methylpropanoic acid, (CH3)2CHCOOH), valeric acid (pentanoic acid, C4H9COOH), isovaleric acid (3-methylbutanoic acid, (CH3)2CHCH2COOH), 2-methylbutanoic acid (CH3CH2CH(CH3)COOH), caproic acid (hexanoic acid, C5H11COOH), 2-methylpentanoic acid (CH3CH2CH2CH(CH3)COOH), 3-methylpentanoic acid (CH8CH2CH(CH3)CH2COOH), 2,2-dimethylbutanoic acid ((CH3)3CCH2COOH), 2,3-dimethylbutanoic acid ((CH3)2CHCH(CH3)COOH) or mixtures thereof. Medium-chain fatty acids selected from enantic acid (heptanoic acid, C6HI3COOH), caprylic acid (octanoic acid, C7H15COOH), pelargonic acid (nonanoic acid, C8HI7COOH), capric acid (decanoic acid, C9H19COOH), undecanoic acid (C10H21COOH), lauric acid (dodecanoic acid, C11H23COOH) or mixtures thereof. c.Selected long-chain fatty acids from myristic acid (acid. tetradecanoic acid, C13H27COOH), pentadecanoic acid (C14H29COOH), palmitic acid (hexadecanoic acid, C15H31COOH), margaric acid (heptadecanoic acid, C16H33COOH), stearic acid (octadecanoic acid, C17H35COOH), nonadecanoic acid (C18H37COOH), arachidic acid (eicosanoic acid, C19H39COOH), heneicosanoic acid (C20H41COOH), palmitoleic acid (9-hexadecenoic acid, C16H30O2), oleic acid (9-octadecenoic acid, C18H34O2), eicosenoic acid (11-eicosenoic acid, C20H38O2), linoleic acid 9,12-octadecadienoic, C18H32O2), acid a-linolenic acid (9,12,15-octadecatrienoic acid, C18H30O2), arachidonic acid (5,8,1 1 ,14-eicosatetraenoic acid, C20H32O2), eicosapentaenoic acid (EPA, 5,8,1 1 ,14,17-eicosapentaenoic acid, C20H30O2), docosahexaenoic acid (DHA, 4,7,10,13,16,19-docosahexaenoic acid, C22H34O2) or mixtures thereof.

9. The method of claim 1, wherein the residence time is between 1 minute and 24 hours.

10. The method of claim 1, wherein the molar ratios of the fatty acid and the zinc precursor in the reaction step are 4:1, 3:1, 2:1, 1:1, 1:

2.

11. The method of claim 8, wherein the fatty acids employed may comprise mixtures of: a. Short-chain fatty acids and medium-chain fatty acids; b. Short-chain fatty acids and long-chain fatty acids; and c. Medium-chain fatty acids and long-chain fatty acids.

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