Pickering Emulsion Structure Using Amphiphilic Particles and Water Pollution Control System Comprising the Same

Abstract

The present invention relates to amphiphilic particles comprising a core particle and an amphiphilic surface layer in which hydrophilic and hydrophobic functional groups are uniformly mixed and distributed on the surface of the core particle, a Pickering emulsion structure utilizing the same, and a water pollution control system comprising the same. Since the amphiphilic particles of the present invention have an amphiphilic structure in which nanoscale functional groups are uniformly mixed on the particle surface, they immediately adsorb to the oil-water interface without specific orientation to form a Pickering emulsion, and by forming a large floc network through self-aggregation, a large amount of spilled oil can be physically recovered using only a simple filter. Furthermore, the invention provides a multifunctional control system that induces biological decomposition without inoculation by attracting native aquatic microorganisms through the hydrogen bond acceptor structure of the residual particles.

Description

Technology Field

[0001] The present invention relates to amphiphilic particles, a Pickering emulsion structure using the same, and a water pollution control system including the same. Background Technology

[0002] Due to the increase in surface transport and the expansion of seabed oil development, the risk of large-scale waterborne oil spills remains persistent; as spilled oil destroys aquatic ecosystems and causes massive economic losses, rapid and effective containment technologies are essential.

[0003] Conventional physical recovery methods widely used for controlling oil spills in water systems, such as oil fences, have limitations in that oil often spreads over the fences in real-world water environments with high waves or strong currents, leading to failure in initial response.

[0004] Chemical treatment methods, such as the application of emulsifiers, can disperse oil slicks from the water surface into the water, but they do not remove the oil itself and merely transfer it to the aquatic ecosystem, and cause serious secondary environmental pollution due to the chemical toxicity of the emulsifiers themselves. In addition, emulsions formed by emulsifiers have low thermodynamic stability, so over time, oil droplets may coalesce and re-aggregate, rising to the surface.

[0005] Biological treatment methods have also failed to overcome the fundamental limitation of extremely slow decomposition rates, as microbial access is restricted due to the immiscible nature of water and oil. Furthermore, the method of inoculating with exotic microorganisms to enhance oil decomposition efficiency poses a risk of ecosystem disturbance, posing a problem that makes it difficult to comply with increasingly stringent international water environment regulations.

[0006] Meanwhile, Pickering emulsion technology stabilized by solid particles has been proposed as a means of oil spill control. However, conventional amphiphilic solid particles mainly employ a Janus structure in which hydrophilicity and hydrophobicity are distinguished by hemispherical regions on the particle surface. Consequently, for the particles to adsorb to the oil-water interface, the orientation of the particles must be aligned so that the hydrophilic and hydrophobic regions face the water side and the oil side, respectively. This dependence on orientation hinders the immediate interfacial adsorption of particles in real aquatic environments with strong waves and currents.

[0007] Therefore, despite continuous technological advancements, conventional oil spill control technologies in water systems are still facing challenges due to insufficient recovery efficiency in dynamic water environments, secondary environmental pollution, limitations in re-coagulation and microbial degradation, and concerns regarding regulatory violations caused by the introduction of alien organisms. Consequently, the development of new control materials and systems capable of overcoming these limitations is required. Prior art literature

[0008] Korean Published Patent No. 10-2019-0069812 Korean Published Patent No. 10-2014-0006449

[0009] RM Atlas et al., Environmental Science & Technology, 45 (2011) 6709-6715S. Pallewatta et al., Marine Pollution Bulletin, 189 (2023) 114813S. Panchal et al., Colloids and Surfaces A, 553 (2018) 541-553 The problem to be solved

[0010] The present invention aims to solve the technical problems of the prior art described above and to provide an amphiphilic particle capable of forming an immediate and irreversible Pickering emulsion at the oil-water interface even in a dynamic water environment by excluding the use of surfactants that cause chemical toxicity and utilizing only the physical and structural properties of solid particles, a Pickering emulsion structure using the same, and a water pollution control system including the same.

[0011] Specifically, the objectives of the present invention are as follows: (i) to provide particles having a uniform amphiphilic surface layer capable of adsorbing immediately to the oil-water interface without relying on the directional alignment of the particles; (ii) to provide a highly stable Pickering emulsion structure that suppresses the coalescence of oil droplets even in actual aquatic environments with strong waves and currents; (iii) to provide a structure capable of mass recovery using only simple physical means such as a sieve by forming a large floc network through self-flocculation between particles; and (iv) to provide a multifunctional control system designed to function as a microreactor in which residual particles can combine with native aquatic microorganisms to induce biological decomposition. means of solving the problem

[0012] One aspect of the present invention relates to an amphiphilic particle comprising a core particle and an amphiphilic surface layer formed on the surface of the core particle, wherein hydrophilic functional groups and hydrophobic functional groups are uniformly distributed thereon, and wherein the amphiphilic surface layer adsorbs to the oil-water interface without specific orientation when in contact with water to form a Pickering emulsion.

[0013] Another aspect of the present invention relates to a Pickering emulsion structure formed by amphiphilic particles surrounding the surface of a droplet of spilled oil according to various embodiments of the present invention.

[0014] Another aspect of the present invention relates to a water pollution control system comprising a Pickering emulsion structure according to various embodiments of the present invention.

[0015] Another aspect of the present invention relates to a method for controlling water pollution, comprising the steps of introducing amphiphilic particles according to various embodiments of the present invention into an oil spill area of ​​a water system, the introduced amphiphilic particles adsorbing to an oil-water interface to form a Pickering emulsion, and physically recovering a floc formed by the self-aggregation of the Pickering emulsion. Effects of the invention

[0016] According to various embodiments of the present invention, amphiphilic particles that adsorb immediately and irreversibly to the oil-water interface even in dynamic water environments using only the physical and structural properties of solid particles without relying on chemical surfactants, Pickering emulsion structures using the same, and water pollution control systems including the same are provided, and ultimately, through this, rapid large-scale recovery and pollution control without secondary pollution can be achieved in the event of an oil spill accident in water.

[0017] The present invention overcomes the limitations of existing technology and provides the following technical advantages.

[0018] First, the amphiphilic particles of the present invention have a "uniform amphiphilic" structure in which hydrophilic and hydrophobic functional groups are uniformly mixed and distributed on the surface of the core particles at the nanoscale, so the orientation dependency of the particles is eliminated, allowing for immediate and irreversible adsorption to the oil-water interface even in actual water environments with strong waves and currents, thereby forming an ultra-highly stable Pickering emulsion that effectively suppresses the re-aggregation of oil droplets.

[0019] Second, the Pickering emulsion structure formed by the amphiphilic particles of the present invention causes self-aggregation through hydrophobic interactions and entanglement between particles and forms a network in the form of a large floc, so that spilled oil can be recovered quickly in large quantities using only a general filter or sieve without expensive special equipment, thereby maximizing physical large-scale recovery efficiency.

[0020] Third, the amphiphilic particles of the present invention can be designed to function as hydrogen bond acceptors by including oxygen (O) and nitrogen (N) elements having non-covalent electron pairs within the molecular structure of the surface layer, thereby forming multiple hydrogen bond networks with hydroxyl groups (-OH) and amino groups (-NH2) present in the cell walls of aquatic native microorganisms to attract microorganisms to the particle surface. Accordingly, the particle surface acts as a microreactor that simultaneously provides the microorganisms with oil (food) and an attachment surface (habitat), thereby inducing complete biological decomposition.

[0021] Fourth, since the present invention uses only non-toxic solid particles without using any toxic chemical surfactants, it can fundamentally prevent secondary water pollution caused by pest control operations, and by adopting a pure structural and physical approach that utilizes only native microorganisms in the site instead of alien microorganisms that pose a risk of disturbing the ecosystem, it can effectively circumvent increasingly stringent international water environment regulatory barriers.

[0022] Fifth, the amphiphilic particles of the present invention are configured such that the core particles have a hollow or porous structure, so that the apparent density of the particles is maintained lower than that of water, thereby providing long-term floating stability on the water surface while securing a large specific surface area to maximize contact efficiency with oil.

[0023] Accordingly, the present invention provides an amphiphilic particle-based Pickering emulsion and water pollution control system that achieves improved interfacial adsorption responsiveness, improved mass recovery efficiency, reduced potential for secondary pollution, and excellent compliance with international regulations compared to conventional water oil spill control technology. Brief explanation of the drawing

[0024] FIG. 1 is a schematic diagram illustrating a five-step oil flocculation and recovery mechanism according to one embodiment of the present invention, in which amphiphilic particles adsorb to an oil-water interface to form a Pickering emulsion, and the formed emulsion self-aggregates to form a floc. FIG. 2 is an experimental photograph and optical microscope image showing Pickering emulsion structures formed by amphiphilic particles according to one embodiment of the present invention self-aggregating to form a large floc shape and stably floating on the surface of seawater. Figure 3 is a photograph of experimental results showing the state in which floc-shaped oil droplets trapped in an amphiphilic particle network according to one embodiment of the present invention are filtered and recovered by a physical sieve (63 μm Sieve) and the seawater below is purified. Specific details for implementing the invention

[0025] Below, various aspects and embodiments of the present invention will be examined in more detail.

[0026] In this specification, expressions such as 'comprising,' 'having,' 'consisting of,' and 'composed of' may include additional parts unless 'only' is used. Furthermore, where a component is expressed in the singular in this specification, it may also include a plurality of components unless specifically stated otherwise. Additionally, numerical values ​​or numerical ranges described in this specification are interpreted to include an error range, even without separate explicit description. Moreover, expressions such as 'X to Y' or 'X-Y' indicating a numerical range in this specification mean 'X or greater and Y or less.'

[0027] The key terms used in this specification are defined below.

[0028] 'Amphiphilicity' refers to the property of a single molecule or particle possessing both a hydrophilic moiety and a hydrophobic moiety simultaneously.

[0029] 'Uniform amphiphilicity' refers to the property in which hydrophilic and hydrophobic functional groups are uniformly mixed and distributed at the nanoscale across the entire particle surface without being separated into specific regions such as hemispheres; this is distinguished from a Janus structure, which has separate hydrophilic and hydrophobic hemispheres.

[0030] A 'Pickering emulsion' refers to an emulsion stabilized by adsorbing solid particles to the oil-water interface instead of conventional surfactants.

[0031] 'Self-aggregation (flocculation)' refers to a phenomenon in which multiple emulsion droplets spontaneously combine to form a network in the form of a large floc through the interaction between particles adsorbed on the surface of the droplets.

[0032] Unless specifically defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.

[0033] Below, various aspects and embodiments of the present invention will be examined in more detail.

[0034] One aspect of the present invention relates to an amphiphilic particle comprising a core particle and an amphiphilic surface layer formed on the surface of the core particle, wherein hydrophilic functional groups and hydrophobic functional groups are uniformly distributed thereon, and wherein the amphiphilic surface layer adsorbs to the oil-water interface without specific orientation when in contact with water to form a Pickering emulsion.

[0035] Unlike Janus particles, which require alignment in a specific direction, the amphiphilic particles according to the present invention immediately adsorb to the oil-water interface regardless of which side of the particle comes into contact, thereby maximizing detachment energy. As a result, even in dynamic aquatic environments with strong waves or currents, the amphiphilic particles according to the present invention envelop oil droplets and form a robust physical barrier (armor).

[0036] If some of the functional groups constituting the amphiphilic surface layer are omitted, or if hydrophilic and hydrophobic functional groups are separated and distributed in specific regions such as hemispheres, unlike the uniform amphiphilic surface layer according to the present invention, interfacial adsorption occurs only when the orientation of the particles is aligned, so the immediate interfacial adsorption in a dynamic aqueous environment is reduced and the stability of the emulsion may be significantly reduced, which is undesirable in that the effects according to various aspects and various embodiments of the present invention cannot be fully expressed.

[0037] According to one embodiment, the core particle may have a hollow structure having an empty space inside, or a porous structure containing a plurality of pores inside. Such hollow or porous structures provide excellent floating properties on the water surface by maintaining the apparent density of the particle itself lower than that of water, and maximize contact efficiency with oil by securing a large specific surface area. The porous structure may be formed in such a way that, for example, when primary nanoparticles aggregate to form secondary particles, the void space formed between adjacent primary particles acts as a pore of the secondary particle.

[0038] In addition, the core particles mentioned above have no particular restrictions on shape and can take various forms such as spherical, semi-spherical, irregular, rod-shaped, or plate-shaped.

[0039] According to another embodiment, the core particles may be selected from hollow silica, secondary particles of porous carbon black, polymer particles, biomass-derived particles, and combinations of two or more of these, but are not particularly limited as long as they are materials satisfying the structural characteristics. Hollow silica is preferred in that it has a large single empty space inside, provides an extremely low apparent density, and maximizes long-term floating stability on the water surface, while secondary particles of porous carbon black are preferred in that primary nanoparticles aggregate to form a large number of micropores inside, providing a very large specific surface area and significantly increasing the oil adsorption capacity per unit weight.

[0040] As polymer particles, for example, polymethyl methacrylate, polystyrene, polyvinyl alcohol, epoxy resin, or melamine-formaldehyde resin manufactured to be hollow or porous may be used, and polymer particles may be desirable in that they have excellent processability and are easy to introduce surface functional groups.

[0041] In addition, biomass-derived particles may be used, for example, carbonized particles derived from cellulose nanocrystals (CNC), cellulose nanofibrils (CNF), lignin, chitosan, starch, biochar, rice husk, cork, or coconut shells, and combinations thereof. Biomass-derived particles are environmentally friendly materials obtained from sustainable biodegradable resources, and they may be desirable in that they are easy to modify for amphiphilicity because they have a large number of hydrophilic functional groups, such as hydroxyl groups or carboxyl groups, distributed abundantly on their surface.

[0042] In particular, as a specific example of the above-mentioned biomass-derived particles, cork fine powder prepared by crushing natural cork (Quercus suber L.) can be used. Cork fine powder has a unique porous form consisting of numerous closed polygonal cell structures, which exhibits an extremely low apparent density, thereby maximizing floating stability on the water surface. It is a natural biomass-derived material composed of suberin, lignin, cellulose, hemicellulose, extractives, etc., and has a rich distribution of hydrophilic functional groups such as hydroxyl groups (-OH) and carboxyl groups (-COOH) on its surface, making amphiphilic surface modification easy. Furthermore, since it is a biodegradable material derived from renewable resources, it has no environmental persistence, so it is particularly desirable in that it can minimize the impact on the ecosystem even when introduced into an aquatic environment.

[0043] According to another embodiment, the amphiphilic surface layer is a layer in which hydrophilic and hydrophobic functional groups are uniformly mixed and distributed at the nanoscale across the entire surface of the core particle. This uniform amphiphilic surface layer enables immediate adsorption equilibrium to be achieved on any side of the particle the moment the particle reaches the oil-water interface, thereby enabling strong interfacial adsorption without the directional alignment required for Janus particles.

[0044] According to another embodiment, the hydrophilic functional group of the amphiphilic surface layer may include a hydroxyl group (-OH), and the hydrophobic functional group may include a methyl group (-CH3), but is not limited thereto. In addition to the hydroxyl group, the hydrophilic functional group may include other functional groups that impart hydrophilicity, such as an amino group (-NH2), a carboxyl group (-COOH), or a sulfonic acid group (-SO3H), and in addition to the methyl group, the hydrophobic functional group may include a long-chain alkyl group (-C n H 2n+1 It may include other functional groups that impart hydrophobicity, such as ).

[0045] According to another embodiment, the amphiphilic surface layer is designed to include oxygen (O) and nitrogen (N) elements having non-covalent electron pairs within its molecular structure and can act as a strong hydrogen bond acceptor. This hydrogen bond acceptor structure forms a multiple hydrogen bond network with hydroxyl groups (-OH) and amino groups (-NH2) that are abundant in the cell walls of aquatic native microorganisms, thereby strongly attracting the microorganisms to the particle surface.

[0046] According to another embodiment, the size of the amphiphilic particles may be 1 nm to 100 μm, and preferably 10 nm to 50 μm. If the particle size is less than 1 nm, the self-aggregation between particles may be insufficient, making it difficult to form large flocs, and if it exceeds 100 μm, the tendency of the particles themselves to settle increases, which may reduce floating ability on the water surface.

[0047] According to a preferred embodiment, if (i) the core particle has a hollow or porous structure, (ii) hydrophilic and hydrophobic functional groups of the amphiphilic surface layer are uniformly mixed and distributed at the nanoscale, and (iii) the amphiphilic surface layer has a structure that acts as a hydrogen bond acceptor by including oxygen (O) and nitrogen (N) elements having non-covalent electron pairs, then adsorption is completed immediately upon the particle reaching the oil-water interface in a dynamic aquatic environment where waves and tides exist, without an orientation alignment process, thereby exhibiting a heterogeneous effect in which the delay time for interfacial adsorption is significantly shortened compared to conventional Janus particles. However, if any of these conditions are not satisfied, such an effect is not manifested. Therefore, it is preferable to satisfy all of the above.

[0048] According to another preferred embodiment, when (iv) the apparent density of the core particles is lower than that of water, (v) the shape of the core particles is spherical or semi-spherical, and (vi) the amphiphilic surface layer is formed substantially continuously over the entire surface of the core particles, a heterogeneous effect can be exhibited in which the mechanical strength of the aggregate is significantly improved by maximizing the hydrophobic interactions and entanglement between particles when a plurality of Pickering emulsion droplets come into contact with each other, thereby enabling large-scale recovery without floc crushing when passing through a sieve, whereas if any one of these is not satisfied, such effect is not exhibited, so it is desirable to satisfy all of the above.

[0049] According to a more preferred embodiment, when all of the above configurations (i) to (vi) are satisfied, the amphiphilic particles spontaneously adsorb to the oil-water interface without orientation immediately after being introduced into the water system to form a robust single-layer (armor) barrier, and multiple emulsion droplets form a large floc network through hydrophobic interactions between particles, while the residual particles attract aquatic microorganisms to the surface through a hydrogen bond acceptor structure, thereby exhibiting heterogeneous effects in which two functions—physical mass recovery and biological complete decomposition induction—are sequentially and simultaneously expressed in a single particle. However, when any one of these is not satisfied, such multi-stage complex effects are not expressed, so it is preferable to satisfy all of the above.

[0050] Whether each configuration (i) to (vi) of the above preferred embodiment is satisfied can be verified by the following analysis method, and if the following criteria are satisfied, the configuration may be deemed to be satisfied.

[0051] (i) Whether the core particles have a hollow or porous structure can be confirmed by observing cross-sections of the particles using scanning electron microscopy (SEM), transmission electron microscopy (TEM), or focused ion beam (FIB)-SEM, and by analyzing Brunauer-Emmett-Teller (BET) nitrogen adsorption-desorption isotherms. For example, if substantially empty spaces (voids) are observed inside the particles in TEM or FIB-SEM cross-sectional images, it corresponds to a hollow structure, and if the BET analysis results show a specific surface area of ​​50 m² 2 If the pore size distribution is greater than or equal to / g, or if the porosity is greater than or equal to 10 volume%, or if a distinct distribution is observed in the micropore (less than 2 nm) or mesopore (2-50 nm) regions, it can be considered to correspond to a porous structure.

[0052] (ii) Whether hydrophilic and hydrophobic functional groups of the amphiphilic surface layer are uniformly mixed and distributed at the nanoscale can be confirmed through surface element and functional group mapping by time-of-flight secondary ion mass spectrometry (TOF-SIMS), phase imaging by atomic force microscopy (AFM), water contact angle measurement, and repeated contact angle measurement performed while rotating the particle. For example, in TOF-SIMS or AFM phase images, hydrophilic domains and hydrophobic domains are observed to be mixed at a scale of 100 nm or less, preferably 10 nm or less, and the water contact angle shows an intermediate value of 30° to 90°, and the deviation of the contact angle measured repeatedly while rotating the particle in any direction is substantially constant within ±10°, whereas it is considered to be uniformly mixed at the nanoscale, whereas if there is a distinct deviation between the two sides, such as the contact angle measured while rotating the particle being less than 30° in one hemisphere and exceeding 90° in the other hemisphere, it can be considered to correspond to a Janus structure.

[0053] (iii) Whether the above-mentioned amphiphilic surface layer is a structure that acts as a hydrogen bond acceptor, including oxygen (O) and nitrogen (N) elements having non-covalent electron pairs, can be confirmed through analysis of elemental composition and bonding state by X-ray photoelectron spectroscopy (XPS), analysis of functional group vibration peaks by Fourier transform infrared spectroscopy (FT-IR), and elemental mapping by energy dispersive X-ray spectroscopy (EDS). For example, if both the O1s peak (approx. 530-534 eV) and the N1s peak (approx. 398-402 eV) are detected in the XPS wide scan spectrum, and the oxygen content in the total atomic ratio of the surface layer is 5 atomic percent or more or the nitrogen content is 1 atomic percent or more, and absorption peaks attributable to C=O (approx. 1,650-1,750 cm-1), CN (approx. 1,000-1,350 cm-1), or NH (approx. 3,300-3,500 cm-1) bonds are observed in the FT-IR spectrum, it can be considered to correspond to a structure acting as a hydrogen bond acceptor.

[0054] (iv) The apparent density of the core particles is the density of water (approx. 1.0 g / cm³) 3 Whether it is lower than ) can be confirmed through the measurement of true density and tap density by gas pycnometry, or through a simple water floating test. For example, if the measured apparent density is 1.0 g / cm³ 3 Less than, preferably 0.8 g / cm³ 3 If the density is lower than or equal to the amount, or if particles introduced into the surface of distilled water remain floating on the water surface for 60 minutes or more without external stirring, the apparent density can be considered lower than that of water.

[0055] (v) Whether the core particles have a spherical or near-spherical shape is determined by analyzing the particle contours of scanning electron microscope (SEM) or transmission electron microscope (TEM) images using the aspect ratio and circularity index (φ = 4πA / P 2 This can be verified by a method of calculating (where A is the projected area and P is the projected perimeter). For example, if the average value of the aspect ratio measured for 100 or more randomly selected particles is in the range of 0.7 to 1.0 and the average value of the sphericity index is 0.8 or higher, it can be considered to correspond to a spherical or semi-spherical shape.

[0056] (vi) Whether the amphiphilic surface layer is formed substantially continuously over the entire surface of the core particle can be confirmed through TEM-EDS elemental mapping combining TEM and energy-dispersive X-ray spectroscopy, STEM-EELS mapping combining scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS), or XPS depth profiling. For example, in TEM-EDS or STEM-EELS mapping, if the characteristic elements constituting the amphiphilic surface layer (e.g., carbon, nitrogen, or elements derived from functional groups) are distributed substantially continuously along the particle outline, and the ratio of the area of ​​the bare core area exposed in the mapping image is 5% or less based on the particle outline length, it can be considered to be formed substantially continuously.

[0057] Another aspect of the present invention relates to a Pickering emulsion structure formed by amphiphilic particles surrounding the surface of a liquid droplet of oil according to various embodiments of the present invention.

[0058] The Pickering emulsion structure according to the present invention has a structure in which the hydrophobic portion of the amphiphilic particles is spontaneously oriented toward the oil droplet side and the hydrophilic portion is oriented toward the water side, thereby enveloping the entire surface of the oil droplet with a single layer or multiple layers of particle barriers. This structure physically blocks direct coalescence between oils even when emulsion droplets come into contact, thereby providing long-term emulsion stability.

[0059] According to one embodiment, the Pickering emulsion structure may be an oil-in-water (O / W) type emulsion structure. The structure exists in a state where oil spilled in an oil spill area of ​​an aqueous system is divided into microdroplets by amphiphilic particles according to the present invention, and the particles are adsorbed onto the surface of each droplet and surrounded by a solid particle barrier.

[0060] According to another embodiment, the Pickering emulsion structure self-aggregates through hydrophobic interactions and entanglement between particles to form a network in the form of flocs. Self-aggregation is a spontaneous phenomenon that occurs when hydrophobic regions come into contact with each other between amphiphilic particles on the surface of adjacent emulsion droplets, and through this process, multiple emulsion droplets are connected to each other to form a large floc network. The flocs thus formed remain floating on the water surface and can be separated and recovered from the water system using simple physical means such as a sieve or a net.

[0061] Another aspect of the present invention relates to a water pollution control system comprising a Pickering emulsion structure according to various embodiments of the present invention.

[0062] A water pollution control system according to the present invention may include (a) a Pickering emulsion structure formed by enveloping oil spilled into a water system, (b) a floc network formed by self-aggregation of the Pickering emulsion structure, and (c) a recovery means for physically recovering oil from the floc network.

[0063] According to one embodiment, the recovery means may be a mesh-structured filter, a net, a skimmer, etc., but is not limited thereto. The mesh size of the filter is not particularly limited and can be appropriately selected according to the representative size of the floc to be recovered. For example, a filter with a larger mesh size may be used when the representative size of the floc is larger, and a filter with a smaller mesh size may be used when the representative size of the floc is smaller. It is also possible to intentionally adjust the representative size of the floc by controlling the amount of amphiphilic particles input and wave and current conditions, and then select a mesh size corresponding to it. As one specific embodiment, a filter having a mesh size of approximately 63 μm may be suitably used.

[0064] According to another embodiment, the water pollution control system may be configured to additionally utilize native microorganisms of the water system to be controlled. The oxygen (O) and nitrogen (N) containing hydrogen bond acceptor structures included in the surface layer of the amphiphilic particles perform the function of attracting native microorganisms of the water system to the particle surface, and the attracted microorganisms biologically decompose oil attached to the surface of residual particles separated from the floc. This configuration enables biological control to be performed using only native microorganisms of the site without inoculation with foreign microorganisms, thereby providing a control system that complies with international water system environmental regulations.

[0065] Another aspect of the present invention relates to a method for controlling water pollution comprising the following steps.

[0066] (A) A step of introducing amphiphilic particles according to various embodiments of the present invention into an oil spill area of ​​an aqueous system;

[0067] (B) a step in which the introduced amphiphilic particles adsorb to the oil-water interface to form a Pickering emulsion; and

[0068] (C) A step of physically recovering the flocs formed by the self-aggregation of the above Pickering emulsion.

[0069] According to one embodiment, step (A) may be performed by spraying the amphiphilic particles in the form of a powder, dispersion, or suspension onto the surface of a water system. The form of the amphiphilic particles and the spraying method may be appropriately selected by a person skilled in the art depending on the area of ​​the water system to be controlled, the amount of oil spill, wave and tide conditions, etc.

[0070] According to another embodiment, physical recovery in step (C) can be performed using a mesh-structured filter, net, skimmer, etc. Since the floc exists in a floating state on the water surface, it can be easily recovered without settling due to gravity.

[0071] According to another embodiment, the water pollution control method of the present invention may further include a step (D) of causing amphiphilic particles remaining on the water surface after step (C) to attract native water microorganisms to the surface to biologically decompose the oil.

[0072] Referring to FIG. 1, the oil flocculation and recovery mechanism by amphiphilic particles according to one embodiment of the present invention consists of the following five steps.

[0073] In Step 1, amphiphilic particles are prepared by performing amphiphilic surface modification so that hydrophilic functional groups (-OH, etc.) and hydrophobic functional groups (-CH3, etc.) are uniformly mixed and distributed at the nanoscale on the surface of core particles ranging in size from several nm to tens of μm. The amphiphilic surface layer formed at this time has two types of functional groups mixed and present across the entire surface without hemispherical region separation.

[0074] In Step 2, the amphiphilic particles are introduced into a contaminated water environment where oil (oil layer) and water (seawater layer) are separated. The particles float stably on the water surface due to their low apparent density resulting from their hollow or porous structure.

[0075] In Step 3, the introduced particles migrate to the oil-water interface and form a Pickering emulsion through adsorption and stabilization. The hydrophobic parts of the particles face the oil, and the hydrophilic parts face the water, constructing a rigid monolayer barrier. Since particle orientation is not required during this process, adsorption occurs immediately.

[0076] In step 4, oil droplets are completely surrounded by particles to form a stable oil-in-water (O / W) Pickering emulsion, and these emulsions begin to aggregate with each other.

[0077] In step 5, aggregated Pickering emulsion droplets form large flocs that float on the water surface, and the oil is recovered and the seawater is purified by physically scooping them out using a net or strainer.

[0078] Referring to FIG. 2, in the experimental results showing that a Pickering emulsion formed by amphiphilic particles according to one embodiment of the present invention exhibits a self-aggregation phenomenon, it is confirmed that a large floc layer in which particles and oil are entangled is clearly separated and floats stably on the water surface. In an optical microscope magnified image, it is observed that a number of fine oil droplets are firmly trapped by the amphiphilic particle network according to the present invention, maintaining a stable floc shape without coalescence.

[0079] Referring to FIG. 3, the network of large floc-shaped oil droplets formed in FIG. 2 can be effectively recovered through a simple physical sieve (63 μm Sieve). The oil droplets trapped in the particle network cannot pass through the mesh of the sieve and are filtered out in the form of clumps on the mesh, and as a result, the water below that passes through the sieve remains in a purified seawater state with the oil removed. This demonstrates that the system of the present invention can rapidly recover a large amount of oil physically without expensive specialized equipment.

[0080] Examples

[0081] The present invention is to be explained in more detail below through examples, etc.; however, the scope and content of the present invention shall not be interpreted as being narrowed or limited by the examples, etc. below. Furthermore, based on the disclosure of the present invention including the examples below, it is evident that a person skilled in the art can easily practice the present invention even without specific experimental results presented, and it is natural that such variations and modifications fall within the scope of the appended claims.

[0082] Furthermore, the experimental results presented below describe only the representative experimental results of the above-mentioned embodiments, and the respective effects of various embodiments of the present invention not explicitly presented below will be described in detail in the relevant sections.

[0083] Example 1: Preparation of hollow silica-based amphiphilic particles

[0084] In this embodiment, hollow silica microspheres having a large single empty space inside were used as core particles. Hollow silica particles provide an extremely low apparent density, maximizing long-term floating stability on the water surface, and facilitate chemically and robustly grafting an amphiphilic surface layer by utilizing silanol groups on the surface.

[0085] Amphiphilic particles according to the present embodiment were obtained by performing amphiphilic surface modification so that hydrophilic functional groups (-OH, etc.) and hydrophobic functional groups (-CH3, etc.) are uniformly mixed and distributed on the surface of the above hollow silica particles at the nanoscale.

[0086] The hollow silica microspheres used in this embodiment have an average diameter in the range of 10–50 μm and a shell thickness of 0.5–2 μm. The apparent density of the hollow silica particles is 0.1–0.3 g / cm³. 3 It is extremely low, allowing for maximum long-term surface buoyancy stability, and the BET specific surface area is 300-500 m² 2 It provides a large surface area at the / g level.

[0087] In order to uniformly mix hydrophilic and hydrophobic functional groups on the surface of the above hollow silica particles, a surface modification reaction using a silane coupling agent is performed. Specifically, 5 g of hollow silica particles are dispersed in 100 mL of a mixed solvent of ethanol and water (volume ratio 8:2), and then 0.5-1.0 wt% of 3-aminopropyltriethoxysilane (APTES) is added for hydrophilic modification, and 1.0-2.0 wt% of hexamethyldisilazane (HMDS) is added for hydrophobic modification, either sequentially or simultaneously. Subsequently, a grafting reaction is carried out by stirring for 12-24 hours while maintaining the reaction temperature at 60-80 ℃. After the reaction is completed, unreacted silane compounds are removed by repeating centrifugation and ethanol washing at least three times, and amphiphilic surface-modified hollow silica particles are obtained by drying in a vacuum oven at 80 ℃ for at least 12 hours.

[0088] Example 2: Preparation of porous carbon black-based amphiphilic particles

[0089] In this embodiment, porous carbon black secondary particles were used as core particles, in which primary nanoparticles aggregate to form numerous fine pores inside. The porous carbon black secondary particles provide a very large specific surface area, resulting in a large oil adsorption capacity per unit weight, and based on the excellent hydrophobicity and lipophilicity characteristic of carbon materials, the affinity with oil can be further enhanced during amphiphilic modification.

[0090] Amphiphilic particles according to the present embodiment were obtained by performing amphiphilic surface modification so that hydrophilic functional groups (-OH, etc.) and hydrophobic functional groups (-CH3, etc.) are uniformly mixed and distributed on the surface of the porous carbon black secondary particles.

[0091] The porous carbon black secondary particles used in this embodiment are formed by the aggregation of primary nanoparticles, with an average diameter in the range of 5–20 μm. These porous carbon black secondary particles contain numerous internal micropores, resulting in a porosity of 60% to 80%, and a BET specific surface area of ​​800–1,200 m². 2 It is very wide at the / g level, resulting in excellent oil adsorption capacity per unit weight.

[0092] To impart amphiphilicity to the surface of the above-mentioned porous carbon black secondary particles, the carbon black particles are first placed in an aqueous solution of nitric acid (HNO3) or hydrogen peroxide (H2O2) (concentration 10-30 wt%) and an oxidation treatment is performed at 60-90 °C for 4-8 hours to introduce hydrophilic functional groups such as carboxyl groups (-COOH) and hydroxyl groups (-OH) to the surface. Subsequently, the oxidized carbon black particles are washed and dried, then dispersed in a toluene or hexane solvent, and 2-5 wt% of octyltrichlorosilane or stearic acid is added relative to the weight of the carbon black to introduce hydrophobic functional groups. The reaction mixture is refluxed and stirred at 70-90 °C for 12-18 hours to perform hydrophobic modification. After the reaction was completed, amphiphilic porous carbon black particles were obtained by drying in a vacuum oven at 100°C after filtration and washing processes, in which hydrophilic and hydrophobic functional groups were uniformly mixed at the nanoscale.

[0093] Example 3: Preparation of Amphiphilic Particles Based on Cork Fine Powder

[0094] In this embodiment, cork fine powder prepared by grinding natural cork (Quercus suber L.) was used as the core particle. Cork is a natural biomass-derived material composed of suberin (about 40-45 wt%), lignin (about 20-25 wt%), cellulose and hemicellulose (about 10-15 wt%), and extractives (about 10-15 wt%), and has an extremely low apparent density due to its unique porous form consisting of numerous closed polygonal cell structures. These structural characteristics are advantageous for maximizing water surface buoyancy stability, and hydrophilic functional groups such as hydroxyl groups (-OH) and carboxyl groups (-COOH), which are abundantly distributed on the surface, function as chemical bonding sites for amphiphilic surface modification.

[0095] To prepare cork fine powder, natural cork discs were dry-ground using a ball mill or jet mill, and then sieved to obtain cork fine powder with an average particle size range of 10–100 μm. The apparent density of the obtained cork fine powder was 0.08–0.15 g / cm³. 3 The density of water (1.0 g / cm³) 3 It is significantly lower than ), making it highly advantageous for surface flotation, and the BET specific surface area is 1-5 m² 2 It was confirmed that the level is / g.

[0096] In order to form an amphiphilic surface layer by uniformly mixing hydrophilic and hydrophobic functional groups at the nanoscale on the surface of the above cork fine powder, a surface modification reaction using a silane coupling agent was performed. Specifically, 5 g of the above cork fine powder was dispersed in 100 mL of a mixed solvent of ethanol and water (volume ratio 9:1), and then 0.5-1.5 wt% of 3-aminopropyltriethoxysilane (APTES) was added for hydrophilic modification, and 1.0-3.0 wt% of trimethylchlorosilane (TMCS) or hexamethyldisilazane (HMDS) was sequentially added for hydrophobic modification. Subsequently, a grafting reaction was carried out by stirring for 12-24 hours while maintaining the reaction temperature at 60-80 ℃. After the reaction was completed, unreacted silane compounds were removed by repeating filtration and ethanol washing at least three times, and by drying in a vacuum oven at 80°C for at least 12 hours, amphiphilic cork fine powder particles in which hydrophilic and hydrophobic functional groups were uniformly mixed at the nanoscale were obtained.

[0097] As a result of measuring the water contact angle of the cork fine powder before and after surface modification, the cork fine powder before modification exhibited intermediate wettability with a contact angle of approximately 85° to 95°; in contrast, it was confirmed that after amphiphilic modification, the adsorption affinity for the oil-water interface was significantly enhanced due to the uniform mixing of hydrophilic and hydrophobic functional groups on the surface. Furthermore, through Fourier transform infrared (FT-IR) analysis, the Si-OC bonding peak of the silane coupling agent (approx. 1,100 cm⁻¹) -1 ) and amino group (-NH 2 NH bending vibration peak of ) (approx. 1,560 cm⁻¹ -1 By confirming the new appearance of ), it was verified that silane functional groups were successfully grafted onto the cork surface.

[0098] Cork is a biodegradable material derived from natural renewable resources. Unlike inorganic or carbon-based materials such as hollow silica or carbon black, it does not persist in the environment, and thus can minimize its impact on the ecosystem even when introduced into an aquatic environment. For this reason, it is particularly desirable as a core material for the amphiphilic particles for water pollution control according to the present invention.

[0099] Test Example 1: Observation of Pickering Emulsion Formation and Autoaggregation

[0100] The amphiphilic particles prepared in Examples 1 and 2 above were introduced into an oil layer floating in seawater, and the formation of Pickering emulsion and self-aggregation behavior by the particles were observed.

[0101] As a result, as shown in Fig. 2, it was confirmed that a large floc layer, in which particles and oil are entangled, is clearly separated and floating stably on the water surface. In optical microscope images, it was observed that numerous fine oil droplets are firmly trapped by an amphiphilic particle network, maintaining a stable floc shape without coalescence.

[0102] As a result of introducing the amphiphilic particles prepared in Examples 1 and 2 above into an oil layer (e.g., crude oil or diesel oil) floating in seawater, the particles immediately migrated to the oil-water interface and formed a stable oil-in-water (O / W) Pickering emulsion. Optical microscopy confirmed that the representative droplet size of the formed Pickering emulsion was in the range of 50-200 μm.

[0103] Over time, the emulsion droplets self-aggregated due to hydrophobic interactions and entanglement between particles, forming a large floc network. The typical size of the formed flocs grew to 1-5 mm and was clearly identifiable with the naked eye. Due to the low apparent density of the particles and the buoyancy of air and oil trapped within the network structure, the flocs stably maintained a floating state on the water surface for at least 72 hours. Furthermore, in a 30-day long-term stability evaluation, no coalescence or phase separation of the emulsion droplets was observed, demonstrating excellent long-term stability in which the number and size distribution of droplets remained similar to the initial state.

[0104] Test Example 2: Physical recovery of floc using a filter screen

[0105] The giant floc formed in Test Example 1 above was recovered using a sieve with a mesh size of 63 μm, and the seawater condition before and after recovery was observed.

[0106] As a result, as shown in Fig. 3, oil droplets trapped in the amphiphilic particle network were not able to pass through the mesh of the filter and were perfectly filtered out in the form of clumps on the mesh, and the water below that passed through the filter remained in a purified seawater state with the oil removed. This demonstrates that the water pollution control system using amphiphilic particles according to the present invention can rapidly and effectively physically recover a large amount of oil using only a simple filter without expensive special equipment.

[0107] An experiment was conducted to physically recover the large flocs formed in Test Example 1 using sieves with various mesh sizes. As a result of the experiment, the oil recovery efficiency was found to be over 98% when using a 63 μm mesh sieve, and the recovery amount per unit time and unit area was approximately 15-20 kg / m³. 2Recovery was possible very rapidly at the min level. After recovery, the residual oil concentration (TPH, Total Petroleum Hydrocarbons) in the bottom seawater was measured and found to be less than 10 ppm, confirming that the seawater was effectively purified.

[0108] As a result of comparing recovery efficiency according to mesh size, a high recovery efficiency of over 99% was observed at a 30 μm mesh, but the recovery speed decreased slightly; at a 100 μm mesh, the recovery speed was fast, but some fine flocs passed through, causing the recovery efficiency to decrease to approximately 92%. Therefore, it was confirmed that a mesh size of 63 μm provides the optimal balance between recovery efficiency and speed.

[0109] Additionally, in a comparative experiment with a control group using a conventional chemical emulsifier (e.g., Tween 80), the conventional emulsifier only finely dispersed the oil and failed to induce self-aggregation, making physical recovery through a sieve almost impossible (recovery efficiency less than 5%), whereas the amphiphilic particles of the present invention formed large flocs, facilitating physical recovery. Furthermore, excellent control performance was proven as the floc network remained stable and undamaged even under artificial wave tide conditions (wave height 0.5 m, period 2 seconds).

[0110] Foregoing, specific parts of the present invention have been described in detail. It is evident to those skilled in the art that such specific descriptions are merely preferred embodiments and do not limit the scope of the invention. Accordingly, the actual scope of the invention is defined by the appended claims and their equivalents.

Claims

Claim 1 A particle for controlling water pollution, comprising: a core particle; and an amphiphilic surface layer formed on the surface of the core particle, wherein hydrophilic functional groups and hydrophobic functional groups are uniformly distributed therein; wherein the amphiphilic surface layer adsorbs to the oil-water interface without specific orientation upon contact with water to form a Pickering emulsion. Claim 2 In claim 1, the core particle is an amphiphilic particle having a hollow structure with an internal empty space or a porous structure containing a plurality of internal voids. Claim 3 In claim 1, the amphiphilic surface layer comprises oxygen (O) and nitrogen (N) elements having non-covalent electron pairs, and is an amphiphilic particle acting as a hydrogen bond acceptor. Claim 4 The amphiphilic particle according to claim 1, wherein the hydrophilic functional group comprises one or more of a hydroxyl group (-OH), an amino group (-NH2), a carboxyl group (-COOH), and a sulfonic acid group (-SO3H), and the hydrophobic functional group comprises one or more of a methyl group (-CH3) and a long-chain alkyl group (-CnH2n+1, provided that n is an integer of 2 or more). Claim 5 In paragraph 2, the core particles are amphiphilic particles selected from hollow silica, secondary particles of porous carbon black, polymer particles, biomass-derived particles, and combinations of two or more of these. Claim 6 In claim 1, the apparent density of the amphiphilic particle is smaller than the density of water. Claim 7 In claim 1, the size of the amphiphilic particles is 1 nm to 100 μm. Claim 8 A Pickering emulsion structure formed by amphiphilic particles according to any one of claims 1 to 7 surrounding the surface of a spilled oil droplet. Claim 9 In claim 8, the Pickering emulsion structure is a Pickering emulsion structure that self-flocculates through hydrophobic interactions and entanglement between particles to form a floc-shaped network. Claim 10 A water pollution control system comprising a Pickering emulsion structure according to paragraph 8. Claim 11 In claim 10, the above-mentioned water pollution control system further comprises a recovery means for physically recovering oil from a floc network formed by the self-aggregation of the Pickering emulsion structure, wherein the recovery means is a water pollution control system selected from a mesh-structured filter, a net, and a skimmer. Claim 12 A water pollution control system according to claim 10, wherein the amphiphilic surface layer includes oxygen (O) and nitrogen (N) elements having non-covalent electron pairs, thereby forming hydrogen bonds with aquatic native microorganisms, so as to induce aquatic native microorganisms to biologically decompose oil attached to the surface of the amphiphilic particles. Claim 13 (A) a step of introducing amphiphilic particles according to any one of claims 1 to 7 into an oil spill area of ​​a water system; (B) a step of the introduced amphiphilic particles adsorbing to an oil-water interface to form a Pickering emulsion; and (C) a step of physically recovering a floc formed by the self-aggregation of the Pickering emulsion; comprising a method for controlling water system pollution. Claim 14 A water pollution control method according to Clause 13, wherein physical recovery in step (C) above is performed using one or more of a mesh-structured filter, a net, and a skimmer. Claim 15 A method for controlling water pollution according to claim 13, further comprising (D) a step in which amphiphilic particles remaining on the water surface after step (C) above attract native water microorganisms to the surface to biologically decompose oil.

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