A method of efficient transformation of crystalline minerals to nanoparticles by salt-containing microdroplets

Abstract

The present invention relates to a method for the efficient transformation of crystalline minerals into nanoparticles using salt-seeded microdroplets. By introducing small concentrations of salts into charged water microdroplets, the electric potential required for effective mineral disintegration is significantly reduced, resulting in enhanced efficiency and safety. The process is applicable to a wide range of minerals and offers a sustainable, cost-effective approach to nanoparticle production. The resulting nanoparticles, ranging in size from 2-10 nm, have applications in catalysis, pharmaceuticals, and advanced materials fabrication.

Description

[0001] COMPLETE SPECIFICATION

[0002] TITLE OF THE INVENTION A METHOD OF EFFICIENT TRANSFORMATION OF CRYSTALLINE MINERALS TO NANOPARTICLES BY SALT-CONTAINING MICRODROPLETS

[0003] FIELD OF THE INVENTION

[0004] The present invention relates to the field of material science and nanotechnology. More specifically, the present invention relates to a method for transforming crystalline minerals into nanoparticles using charged water microdroplets containing salts. This method offers enhanced efficiency and reduced energy requirements compared to conventional techniques.

[0005] BACKGROUND OF THE INVENTION

[0006] The transformation of crystalline minerals into nanoparticles is a critical process in various industries, including catalysis, pharmaceuticals, and electronics. Conventional methods involve high-energy ball milling, chemical reduction, or thermal treatments, which are energy-intensive and costly. The advent of microdroplet technology, as demonstrated in the prior patent application, “A Method to Transform Crystalline Minerals to Nanoparticles by Microdroplets” (T. Pradeep et al., patent no. 539562), has introduced a less energy-intensive alternative. However, the process described in the prior art requires the application of a high electric potential (approximately 4.5-4 kV) to achieve effective mineral disintegration. This high voltage poses challenges in terms of operational costs and safety. The current invention addresses these limitations by incorporating a small concentration of salt into the microdroplets, which significantly reduces the required electric potential and associated energy consumption. Additionally, the inclusion of salt enhances the microdroplets' mineralization capability by reducing the resultant particle size. This improvement indicates that salt-seeded microdroplets enable better mineralization at lower potentials, thereby further decreasing energy consumption.

[0007] Mineral disintegration under ambient conditions remains one of the most challenging transformations in chemistry and geochemistry, as most minerals exhibit exceptional lattice stability and chemical inertness [Jia, X et al., JACS Au 2024, 4 (11), 4141-4147], Traditional methods of mineral processing, such as mechanical grinding, high-temperature oxidation, or acid leaching, are energy-intensive and often environmentally detrimental. Recently, charged watermicrodroplets have been recognized as exceptional microreactors capable of promoting otherwise inaccessible reactions through the generation of strong interfacial electric fields [Xia, Y et al., J. Phys. Chem. A 2024, 128 (28), 5684-5690; Li Z et al., Nano Lett. 2025, 25 (6), 2210-2218; Wuthrich, C et al., J. Am. Soc. Mass Spectrom. 2023, 34 (11), 2498-2507], extreme ion concentration gradients, and rapid charge separation at the air-water interface [Lacour, R. A el al., j. Am. Chem. Soc. 2025, 147 (8), 6299-6317; Holden, D. T. etal., Chem. Sci. 2025, 16 (37), 17020-17033; Maltby, K. A et al., ACS Sustainable Chem. Eng. 2023, 11 (23), 8675-8684; Lee, J. K. et al., Proc. Natl. Acad. Sci. U.S.A. 2019, 116 (39), 19294-19298], Such distinct physicochemical features have enabled diverse phenomena, including accelerated chemical reactions [Maltby, K. A et al., ACS Sustainable Chem. Eng. 2023, 11 (23), 8675-8684; Lee, J. K et al., Quart. Rev. Biophys. 2015, 48 (4), 437-444], spontaneous formation of nanomaterials from homogeneous metal salt precursor solutions, etc [Lee, J. K et al., Nat Commun 2018, 9 (1), 1562; Li, M et al., Chem. Sci. 2024, 15 (33), 13429-13441; Eatoo, M. A et al., Chem. Sci. 2025, 16 (3), 1115-1125; Spoorthi, B. K et al., Science 2024, 384 (6699), 1012-1017], Central to microdroplet reactivity is the interplay between droplet charge density, electrical conductivity, and interfacial polarization [Li Z et al., Nano Lett. 2025, 25 (6), 2210-2218; Miles, B. E. A et al., J. Phys. Chem. A 2025, 129 (3), 762-773; Gong, K et al., J. Am. Chem. Soc. 2024, 146 (46), 31585-31596], Conductivity in the aqueous phase controls charge relaxation kinetics, Rayleigh instability thresholds, and electro-hydrodynamic deformation modes, all of which govern energy transfer efficiency during mineral disintegration. Enhancing conductivity promotes faster charge redistribution and localized electric field amplification, facilitating droplet fission, surface polarization, and bond cleavage processes critical for mineral breakdown [Eatoo, M. A et al., J. Am. Chem. Soc. 2025, 147 (39), 35392-35400; Chen, H et al., J. Am. Chem. Soc. 2025, 147 (13), 11399-11406; Lee, K etal., J. Am. Chem. Soc. 2025, 147 (36), 33240-33247], Recently, our group has demonstrated an interesting aspect of charged water microdroplets, namely they spontaneously disintegrate minerals such as quartz and ruby into nanoparticles within milliseconds under ambient conditions [Spoorthi, B. K et al., Science 2024, 384 (6699), 1012-1017], This microdroplet-mediated weathering is driven by combined factors, including intense interfacial electric fields, proton-induced slippage, large applied potential, and the droplet's flight path and Coulombic explosion of droplets [Spoorthi, B. K et al., Science 2024, 384 (6699), 1012-1017; Rayleigh, Lord. XX Journal of Science 1882, 14 (87), 184-186],The intricate balance of chemical, electrostatic and hydrodynamic factors directly impacts the properties of nanoparticles formed through microdroplet-mediated mineral disintegration. Such nanoparticles exhibit distinct physicochemical and catalytic properties compared to their bulk counterparts [Gong, K et al., J. Am. Chem. Soc. 2024, 146 (46), 31585-31596; Carreira Mendes Da Silva, Y.et al., J. Am. Chem. Soc. 2025, 147 (31), 27768-27776], including enhanced surface area, tunable reactivity, and modified electronic structures. These attributes enable advanced applications in catalysis, environmental remediation, and biomedicine, providing a strong incentive for the development of efficient and scalable strategies to convert minerals into functional nanoparticles [Mahapatra, A. et al J. chem. communic. 2025, 61(81), 15846-15849; Spoorthi, B. K et al., Science 2024, 384 (6699), 1012-1017],

[0008] Although this fascinating research has opened many exciting possibilities, two major limitations remain for practical relevance: the high operational potential required for effective mineral disintegration (> 4-4.5 kV) [Mahapatra, A. et al J. chem. communic. 2025, 61(81), 15846-15849; Spoorthi, B. K et al., Science 2024, 384 (6699), 1012-1017]and the reliance on high-purity water, which reduces the overall cost-effectiveness of the process. In natural aqueous environments, minerals coexist with dissolved salts. Ionic additives modulate droplet conductivity and interfacial charge dynamics, influencing droplet stability and local electric field intensity.

[0009] OBJECTIVE OF THE INVENTION

[0010] The primary objective of the present invention is to demonstrate that introducing trace concentrations of salts (0.1 ppm) into water significantly reduces the threshold potential for quartz disintegration by up to 65%, resulting in the formation of 2-10 nm nanoparticles at voltages as low as 1.5 kV.

[0011] The other objective of the present invention aims to do a systematic investigation across varying salt concentrations and ionic sizes, ranging from H+to Cs+for cations and F to I" for anions, demonstrates that smaller, more mobile ions induce stronger interfacial polarization and localized field amplification. The findings highlight a green, energy- efficient, and scalable strategy for the ambient synthesis of mineral-derived nanomaterials inspired by natural aqueous processes.SUMMARY OF THE INVENTION

[0012] The present invention relates to a novel method for the efficient disintegration of crystalline minerals into nanoparticles using salt-seeded microdroplets. By introducing small concentrations of salts (in parts-per-million levels) into charged water microdroplets, the electric potential required for effective mineral disintegration is significantly reduced. This advancement addresses both cost and safety concerns associated with high-voltage processes.

[0013] In one embodiment, the present invention relates to a method for the efficient disintegration of crystalline minerals into nanoparticles using salt-seeded microdroplets. The said method comprises when aqueous solutions containing trace concentrations of salts (0.1 ppm) are electrosprayed, the threshold potential for quartz disintegration decreases by up to 65%, leading to the formation of 2-10 nm nanoparticles at voltages as low as 1.5 kV. Systematic variation in salt concentration reveals that enhanced droplet conductivity, surface tension, interfacial charge polarization, and localized electric field amplification collectively facilitate efficient mineralization at lower voltages. The effect of ionic size was systematically investigated through different cations (H+to Cs+) and anions (F to I"), establishing that smaller ions promote stronger field localization and faster charge relaxation dynamics. This salt-assisted electrospray route offers a green, energy-efficient, and scalable strategy for ambient synthesis of mineral-derived nanomaterials.

[0014] BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Field emission scanning electron microscopic (FESEM) image of ground and separated natural quartz used for electrospray, showing that the size range of particles is between 5-10 pm. A few smaller particles that are naturally adhered to the micron-sized particles remain attached even after ultrasonication.

[0016] Figure 2 Disintegration of quartz particles in water containing 0.5 ppm NaCl, under varied electrospray conditions. (A-F) TEM images of quartz particles obtained after electrospray at applied potentials ranging from 4.5 to 2.0 kV, with a tip-to- substrate distance of 1.5 cm. TEM images without (G) and with (H) NaCl showing that even trace amounts of salt markedly enhanced the disintegration efficiency, by reducing the required applied voltage from 4.5 to 2.5 kV (by 55%). (I) HRTEM image of an individual quartz nanoparticle showing distinct lattice fringes with an interplanar spacing of 0.24 nm, corresponding to the (110) plane of quartz.Figure 3 Disintegration of quartz particles in NaCl solution. (A to D) TEM images of quartz after electrospray of quartz suspension in different concentrations of NaCl: (5 ppm, 0.5 ppm, 0.1 ppm and 0.05 ppm respectively) at an applied potential of 2.0 kV, with a tip-to-substrate distance of 1.5 cm. High-resolution TEM image of a particle is shown in the inset of B. The plane shown is (110) of quartz.

[0017] Figure 4 Disintegration of quartz particles in charged water microdroplets containing acid (HC1) and salt solutions at ppm levels. (A-F) Transmission electron microscopic (TEM) images showing morphological variations of quartz particles (suspended in different alkali metal chloride solutions) after electrospray at an applied potential of 2.0 kV, with a tip-to-substrate distance of 1.5 cm and salt concentration of 0.1 ppm. (G-J) TEM images of quartz particles suspended in different sodium halide solutions (NaF, NaCl, NaBr, and Nal, respectively) following electrospray under identical conditions (2.0 kV, 1.5 cm, 0.1 ppm). Distinct morphological features highlight the influence of ionic composition on disintegration efficiency and particle transformation behavior.

[0018] Figure 5 Transmission electron microscopic (TEM) images after electrospray showing the disintegration of quartz particles suspended in (A) HC1 and (B) LiCl solutions under an applied potential of 1.5 kV at a tip-to-substrate distance of 1.5 cm, demonstrating uniform nanoparticle formation facilitated by proton- and Li+-assisted cleavage.

[0019] Figure 6 Disintegration of quartz particles after electrospraying, suspended in (A) HC1 and (B) NaCl solutions (equal concentration of 1.5 pM) in charged water microdroplets generated at an applied potential of 2.0 kV and a tip-to-substrate distance of 1.5 cm facilitated the formation of quartz nanoparticles.

[0020] Figure 7 Particle size distribution for nanoparticles of quartz.

[0021] Referring to the drawings, the embodiments of the present invention are further described. The figures are not necessarily drawn to scale, and in some instances the drawings have been exaggerated or simplified for illustrative purposes only. One of ordinary skill in the art may appreciate the many possible applications and variations of the present invention based on the following examples of possible embodiments of the present invention.

[0022] DETAILED DESCRIPTION OF THE INVENTIONThe following description is presented to enable any person skilled in the art to make and use the embodiments, and is provided in the context of a particular application and its requirements. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the scope of the present invention. Thus, the present invention is not limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein.

[0023] The present invention relates to a method for transforming crystalline minerals into nanoparticles through the application of salt-seeded microdroplets. This innovative approach achieves efficient disintegration of crystalline minerals by utilizing small concentrations of salts (in parts-per-million levels) within charged water microdroplets, thereby significantly reducing the electric potential required for effective mineral disintegration.

[0024] Charged water microdroplets have been demonstrated to be microreactors capable of disintegrating hard minerals into nanoparticles under ambient conditions. However, the high applied potentials required (-4-4.5 kV) limit the energy efficiency. Herein, we demonstrate that when aqueous solutions containing trace concentrations of salts (0.1 ppm) are electrosprayed, the threshold potential for quartz disintegration decreases by up to 65 %, leading to the formation of 2-10 nm nanoparticles at voltages as low as 1.5 kV. Systematic variation in salt concentration reveals that enhanced droplet conductivity, surface tension, interfacial charge polarization, and localized electric field amplification collectively facilitate efficient mineralization at lower voltages. The effect of ionic size was systematically investigated through different cations (H+to Cs+) and anions (F to I"), establishing that smaller ions promote stronger field localization and faster charge relaxation dynamics. This salt-assisted electrospray route offers a green, energyefficient, and scalable strategy for ambient synthesis of mineral-derived nanomaterials.

[0025] Materials Used

[0026] River sand was collected from the local market. Ultrapure milli-Q water (18.5 M ) was used for all the experiments along with the addition of different concentrations of NaCl (> 99.0%) (0.4-4 ppm). The sample was ground with mortar and pestle, suspended in water containing NaCl, and ultrasonicated with a digital ultrasonic cleaner (40 kHz, 100 W) for twominutes, then centrifuged to get cleaned quartz. A fused silica capillary of inner diameter 50 pm was used for the electrospray process.

[0027] Preparation of suspension of quartz

[0028] River sand was first washed multiple times with deionized water, dried, and sieved to isolate quartz particles. The quartz was finely ground using a mortar and pestle. Approximately 10 mg of quartz powder was suspended in 2 mL of Milli-Q water, followed by ultrasonication for 2 minutes to achieve uniform dispersion. The suspension was centrifuged at 1000 rpm for 1 minute to remove large particulates. The supernatant was collected and ultrasonicated again for 2 minutes, followed by sequential centrifugation at 15,000 rpm to eliminate both large and ultrafine nanoparticles. The intermediate fraction produced as precipitate (~ 0.4 mg quartz) was retained for subsequent salt addition and electrospray experiments.

[0029] Preparation of NaCl Stock Solutions

[0030] A stock solution of NaCl (5 mg / mL) was prepared by dissolving 5 mg NaCl in 1 mL of Milli-Q water and ultrasonicated to ensure complete dissolution. 10 pL of the prepared solution was diluted in 990 pL water to obtain a 0.05 mg / mL solution consisting NaCl in it. Serial dilutions were then performed to obtain concentrations corresponding to 5 ppm (85.6 pM), 0.5 ppm (8.56 pM), 0.1 ppm (1.71 pM), and 0.05 ppm (0.856 pM).

[0031] For each experiment, 0.5 mL of the desired NaCl solution was added to the quartz suspension (Sample 1: described in Preparation of precursor suspension for electrospray) prepared above to achieve the final salt concentration. Before electrospray deposition, 20 pL aliquots of each quartz-NaCl mixture were dropcasted onto aluminium substrate and imaged with field emission scanning electron microscopy (FESEM) to verify the uniformity and particle size of quartz in the suspension used further for electrospraying.

[0032] Preparation of precursor suspension for electrospray

[0033] A 200 pL aliquot of Sample 1 was mixed with 800 pL of the respective NaCl solution to achieve the target concentration while maintaining the constant amount of quartz (~ 0.4 mg) in it. The mixture was ultrasonicated well to ensure homogenization and loaded into a gastight Hamilton syringe (0.5 mL).The syringe was connected to a polyimide coated fused silica capillary (inner diameter 50 pm, Polymicro Technologies™, Molex, USA) via a union connector. A high-voltage DC power supply (Physics Instruments Co., India) was attached to the syringe needle, and a stepper-motor-controlled syringe pump maintained a steady flow rate of 0.1 mL h-1. Carbon-coated copper TEM grids (300 mesh) served as the grounded collector, placed at a tip-to-substrate distance of 1.5 cm.

[0034] All electrospray experiments were performed under ambient laboratory conditions (25 °C, 50-60 % relative humidity). The applied potential was varied from 1.5 to 4.5 kV depending on the salt concentration and type of ion used in the experiment.

[0035] Electrospray deposition experiments

[0036] A custom-built electrospray setup was employed to generate charged microdroplets. A 0.5 mL gas-tight Hamilton syringe fitted with a 22-gauge needle (inner diameter 413 pm) was connected to a polyimide coated fused silica capillary (inner diameter 50 pm, Polymicro Technologies™, Molex, USA) using a union connector. The syringe needle was connected to a high-voltage DC power supply, while the collection substrate-carbon-coated copper TEM grid (300 mesh) - was grounded and placed on a metal plate 1.5 cm below the capillary tip.

[0037] A stepper motor with 400 steps per revolution was used to precisely control the flow rate at 0.1 mL / h. Experiments were carried out under ambient conditions (25 °C, 50-60 % RH). Applied potentials ranged between 1.5 and 4.5 kV depending on salt concentration. PEEK tubing, ferrules, and connectors were procured from IDEX Health & Science, USA.

[0038] Morphology of Pristine Quartz

[0039] Pristine quartz particles, characterized by field emission scanning electron microscopy (FESEM), exhibited sizes in the range of 5-10 pm with well-defined crystalline edges (Figure 1). This confirmed the structural integrity of the particles prior to treatment of electrospray. Electrospraying quartz suspensions in ultrapure water (18 MQ cm, Milli-Q) required an applied potential of at least 4.5 kV to achieve disintegration to form nanoparticles, consistent with earlier reports on charged water microdroplet-induced mineral weathering.

[0040] Effect of equal ionic concentration on the disintegration of quartzA controlled comparison between equal number of ions of HC1 and NaCl (1.5 pM each) was performed under identical electrospray conditions (2.0 kV, 1.5 cm tip-to-substrate distance) to isolate the influence of ion type from ionic strength. Both systems produced uniform quartz nanoparticles, confirming that ion availability governs disintegration. However, H+ions enabled disintegration at lower voltages (1.5 kV) due to proton-assisted breakage and enhanced interfacial polarization, whereas Na+required higher fields (2.0-2.5 kV). This demonstrates that hydration strength and interfacial chemistry upon introduction of different kinds of ions, rather than ionic concentration alone, dictate the energy efficiency of charged droplet-induced disintegration of quartz.

[0041] Mechanistic insights into salt-assisted disintegration of quartz

[0042] The observed reduction in required potential upon NaCl addition arises from a synergistic interplay of electrostatic, interfacial, and mechanical effects within the charged microdroplets. Trace ionic impurities elevate droplet conductivity, promoting rapid charge redistribution and field localization at the droplet surface, which enhances electrohydrodynamic instability and accelerates Rayleigh fission. Na+and Ch ions amplify Coulombic repulsion, facilitating finer droplet formation and efficient energy transfer to the quartz-water interface. The resulting localized electric fields weaken Si-0 bonds, promoting crystal lattice slippage and controlled fragmentation. At potentials > 2.5 kV, these effects dominate, leading to uniform nanoparticle formation; however, below 2.0 kV, insufficient charge density results in partial cleavage and aggregation. Thus, NaCl-assisted electrospray achieves up to 50 % reduction in energy input while maintaining nanoparticle crystallinity and uniformity.

[0043] Experimental Results

[0044] For all the experiments, quartz particles with particle sizes of 5-10 pm were suspended in ultrapure milli-Q water (18 MQ cm) containing 0.5 ppm (8.56 pM) NaCl, followed by ESD using a polyimide coated fused silica capillary (ID = 50 pm) at applied potentials ranging from 2 to 4.5 kV and a fixed tip-to-substrate distance of 1.5 cm. Quartz nanoparticles generated by electrospray deposition (ESD) of aqueous suspensions of quartz, containing 0.5 ppm NaCl, were systematically characterized using transmission electron microscopy (TEM), as depicted in Figure 2. Figure 2 (A-E) illustrate the morphology of nanoparticles (NPs) formed under appliedpotentials ranging from 4.5 to 2.5 kV, respectively. These TEM images confirm the efficient and energy-saving disintegration of quartz within this voltage range. Notably, at an applied potential of 2.0 kV (Figure 2F), the formation of predominantly larger aggregates was observed, indicative of incomplete disintegration and establishing a critical lower threshold for effective nanoparticle synthesis. Large-area TEM images acquired at 4.5 kV and 2.5 kV (Figures 2G and 2H, respectively) further confirm the consistent production of nanoparticles with a narrow size distribution, ranging from 2 to 10 nm. High-resolution TEM (HRTEM) analysis (Figure 21) reveals lattice fringes with a spacing of 0.24 nm, corresponding to the (110) crystallographic plane of quartz, thereby confirming the crystalline integrity of the nanoparticles. The starting material used for the ESD was quartz particles of sizes ranging from 5 to 10 pm, as verified by field emission scanning electron microscopy (FESEM) shown in Figure 1 confirming the substantial size reduction achieved post-electrospray deposition.

[0045] In control experiments conducted in the absence of salt, quartz disintegration was initiated only at applied potentials exceeding 4.5 kV, producing NPs within the 5-10 nm size range, which aligns with the previous observations. The introduction of 0.5 ppm NaCl lowered this voltage threshold to 2.5 kV, reflecting a significant reduction of approximately 55 % in the energy input required. However, voltages below 2.0 kV resulted in incomplete mineral fragmentation, characterized by aggregate formation. Through systematic optimization, an optimal NaCl concentration of 0.1 ppm was identified, effectively balancing solution conductivity and surface tension parameters. Collectively, these findings demonstrate that addition of traces of common salt markedly enhances the efficiency of quartz disintegration in charged microdroplets at substantially reduced applied voltages.

[0046] To identify the optimum NaCl concentration for efficient quartz disintegration, electrospray experiments were conducted at 2.0 kV with a tip-to-substrate distance of 1.5 cm, and the resulting material was imaged using TEM (Figures 3 A-D). The images reveal that at low salt concentrations (< 0.05 ppm), the ionic strength was insufficient to facilitate effective charge transport to the droplet interface, resulting in a behavior similar to ultrapure water and the formation of larger aggregates. Conversely, at higher salt levels (> 0.5 ppm), strong ion-solvent interactions lead to increased surface tension, which compromises droplet stability and promotes aggregation. There is a direct correlation between salt concentration and surface tension. These observations establish that an intermediate concentration of 0.1 ppm NaCl optimally balancessolution conductivity and surface tension, thereby enabling efficient formation of well-dispersed quartz nanoparticles upon electrospraying. This finding complements the potential-dependent disintegration efficiencies described in Figure 2 and highlights the crucial interplay between ionic concentration and electro-hydrodynamic parameters in modulating mineral fragmentation.

[0047] Nature of the ion exerts a significant influence on both the energy efficiency of quartz disintegration and the morphology of the resulting nanoparticles. To investigate this, we studied a series of alkali metal chlorides (LiCl to CsCl) and observed systematic variations in NP size, which correlated inversely with solution conductivity and directly with the cation radius. Smaller cations, such as Li+, enhance ionic mobility and solution conductivity, facilitating more effective charge transport to the droplet interface. This results in more efficient droplet deformation and fragmentation, facilitating quartz nanoparticle formation at the lowest observed energy threshold of 1.5 kV (Figure 4). HC1 displayed comparable efficiency, indicating that proton- induced slip of the assisted hydrolysis and facilitated lattice has a role in mineral disintegration, plane slippage play a role in Si-0 bond cleavage, further lowering the energy barrier for disintegration. In contrast, larger alkali cations like K+and Cs+produced distinctly different effects. These ions induced anisotropic nanoparticle morphologies and “flowery” aggregate structures (Figures 4 A-F). We attribute this to the weaker hydration shells associated with larger ionic radii, which reduce solvation layer stability and thereby promote enhanced interparticle bridging and aggregation. These morphological effects underscore how ion hydration dynamics influence droplet stability and particle fragmentation pathways during ESD.

[0048] To further describe the effect, we investigated the influence of anionic species by examining sodium halides (NaF to Nal). TEM analyses (Figures 4 G-J) reveal that a decrease in anion polarizability correlates with a higher tendency to form aggregates, as seen for NaF, which limits disintegra-tion efficiency. Conversely, as the ionic character and polarizability increase, from NaBr to Nal, there is enhanced charge density and conductivity within droplets, resulting in the formation of monodisperse nanoparticles with improved quartz disintegration. Collectively, these findings highlight the critical interplay of ionic size, mobility, hydration, and polarizability in governing the electro-hydrodynamic and chemical processes that mediate mineral disintegration in charged microdroplets. Through precise ion selection, it is possible to tailor mineral nanoparticle synthesis to achieve optimal energy efficiency and morphological control under ambient conditions.The pathways of salt-assisted quartz disintegration, including the impact of equal ionic concentrations on electro-hydrodynamic behavior and interfacial charge distribution is illustrated in Figures 5 and 6, the transmission electron microscopic (TEM) analysis of quartz particle disintegration under electrospray conditions. As shown in Figure 4, quartz particles suspended in HC1 and LiCl solutions were subjected to electrospraying at an applied potential of 1.5 kV and a tip-to-substrate distance of 1.5 cm, resulting in pronounced particle cleavage and uniform nanoparticle formation attributed to proton- and Li+-assisted fragmentation within the charged microdroplets. Figure 6 further demonstrates the disintegration behavior of quartz particles electrosprayed from suspensions containing HC1 and NaCl solutions of equal concentration (1.5 pM) under an applied potential of 2.0 kV and a tip-to-substrate distance of 1.5 cm. The charged water microdroplets generated under these conditions facilitated effective particle breakdown and subsequent formation of quartz nanoparticles.

[0049] The observed salt-induced enhancement of quartz disintegration by charged water microdroplets appears to arise from multiple synergistic effects: (1) increased solution conductivity leading to efficient charge mobility (2) enhanced interfacial charge polarization facilitating Si-0 bond cleavage etc.

[0050] This study demonstrates a tunable regime in charged water microdroplet-mediated disintegration of natural minerals, where ionic concentration, their type, and size critically determine nanoparticle size, morphology, and uniformity. We find that proton- and lithium-ion-assisted cleavage mechanisms offer the lowest energy pathways, significantly reducing the applied potential threshold for quartz disintegration by up to 65 %, with nanoparticles as small as 2-10 nm (shown in figure 7) formed at voltages as low as 1.5 kV.

[0051] The method demonstrates energy efficiency, as reduced electric potential translates to lower energy consumption and operational costs. It offers scalability due to its simplicity and cost-effectiveness, making it suitable for industrial applications. Safety is enhanced through the use of lower applied voltages, reducing risks associated with high-voltage systems. The method also minimizes environmental impact by avoiding harsh chemicals and high temperatures.

[0052] Thus, the present invention represents a significant improvement over existing methods for transforming crystalline minerals into nanoparticles. By incorporating salts into charged water microdroplets, the process achieves enhanced efficiency, reduced energy consumption, andgreater environmental sustainability. This advancement has the potential to revolutionize industries reliant on nanoparticle production and mineral processing.

[0053] It may be appreciated by those skilled in the art that the foregoing drawings, examples and experimental evidences are merely illustrative and are not to be taken as limitations upon the scope of the invention.

Claims

We Claim1. A method for transforming crystalline minerals into nanoparticles, the method comprising the steps ofa. suspending crystalline minerals into charged water microdroplets, wherein the microdroplets contain salts up to 3 parts per million (ppm),b. subjecting the suspension to electrospray deposition through a capillary at an applied potential up to 4.5 kV and up to 1.5 cm tip-to-substrate distance;wherein, the said salt enhances the efficiency of crystalline mineral disintegration in charged microdroplets at substantially reduced applied voltages.

2. The method as claimed in claim 1, wherein the crystalline mineral is quartz.

3. The method as claimed in claim 1, wherein the quartz particles with particle sizes of 5-10 pm 4. The method as claimed in claim 1, wherein the salt includes sodium chloride (NaCl), lithium chloride (LiCl), and acid like hydrogen chloride (HC1).

5. The method as claimed in claim 1, wherein the electric potential applied is reduced by up to 65% using optimized salt compositions.

6. The method as claimed in claim 1, wherein the microdroplets are generated through an electrospray deposition process involving the use of a fused silica capillary with an inner diameter of 50 pm.

7. The method of claim 1, wherein the nanoparticles produced have a particle size ranging from 2 to 10 nm.

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