Nanoparticle-stabilized fire-fighting foams

Abstract

The present invention relates generally to nanoparticle-stabilized fire-fighting foam concentrates, fire-fighting foam solutions, and fire-fighting foams prepared from the concentrates or solutions of the present invention that contain one or more silica nanoparticles (e.g., silica nanoparticles, silica nanoparticles, silica nanoparticles, silica nanoparticles, silica nanoparticles, silica nanoparticles, silica nanoparticles, silica nanoparticles, silica nanoparticles, silica nanoparticles, silica nanoparticles, silica nanoparticles, silica nanoparticles, silica nanoparticles, silica nanoparticles, surface modified silica nanoparticles) and any one or all of one or more components selected from the group consisting of one or more organic solvents, one or more surfactants, one or more biopolymers, and one or more alcohols. The invention also relates to a method for increasing the resistance of fire-fighting foams to polar solvents. The present invention also relates to methods of making fire foam concentrates comprising silica nanoparticles (e.g., surface-modified silica nanoparticles).

Description

[0001] Citation of Related Applications

[0002] This application claims the benefit and priority of U.S. Provisional Patent Application Serial No. 63 / 403,510, filed on September 2, 2022, the entire content of which is incorporated herein by reference for all relevant purposes. Technical Field

[0003] The present invention generally relates to nanoparticle-stabilized fire-fighting foam concentrates, fire-fighting foam solutions, and fire-fighting foams prepared from the concentrates or solutions of the present invention, the concentrates or solutions containing one or more silica nanoparticles (e.g., surface-modified silica nanoparticles) and any one or all of one or more components selected from one or more organic solvents, one or more surfactants, one or more biopolymers, and one or more alcohols. The present invention also relates to methods for improving the tolerance of fire-fighting foams to polar solvents. The present invention also relates to methods for preparing fire-fighting foam concentrates containing silica nanoparticles (e.g., surface-modified silica nanoparticles). Background Art

[0004] Aqueous fire-fighting foams are used to extinguish Class B fires (i.e., fires caused by the combustion of flammable liquids). Such fire-fighting foams include both aqueous film-forming foams (AFFF) and alcohol-resistant aqueous film-forming foams (AR-AFFF). In recent years, due to toxicity concerns, fluorine-free aqueous fire-fighting foams have been developed. Suitable fluorine-free foams have been developed. However, there are opportunities for improvement in such foams.

[0005] For example, certain fluorine-free foams utilize silicone-based surfactants, which may be undesirable for toxicity reasons. Thus, in some cases, an effective silicone-free and fluorine-free foam may be desired.

[0006] An important use of fluorine-free fire-fighting foams is in relation to polar solvent (e.g., isopropyl alcohol) fuel fires. Polymers in the foam formulation will seal the fuel surface, thereby inhibiting vapor release and separating the fuel and air to extinguish the fire. Effective alcohol-containing foams (e.g., prepared from alcohol-type concentrate ATC) have been prepared, which contain additives to prevent the polar solvent from mixing with the water in the foam bubbles and disrupting the covering layer. While such foams are effective, similar performance foams that do not require certain additives may be desired. For example, foams that exhibit such tolerance have been prepared, but typically contain fatty alcohol defoamers. While effective foams containing an alcohol component have been used, in some cases, the fatty alcohol defoamers may weaken the generated foam. Thus, in some cases, an effective (fluorine-free) fire-fighting foam that does not require an alcohol component may be desired.

[0007] Concentrates for fire-fighting foams are typically tested for their foaming properties in conjunction with different water sources, including fresh water and salt water (such as sea water, including sea water having a high total suspended solids). Foams that exhibit suitable performance in conjunction with a variety of water sources are desired, for example to provide flexibility in use. SUMMARY OF THE INVENTION

[0008] Briefly, thus, certain embodiments of the present invention relate to a fire-fighting foam concentrate comprising silica nanoparticles (e.g., surface-modified silica nanoparticles), wherein the silica nanoparticles have a silica (SiO2) content of at least about 50 wt%; one or more organic solvents, wherein the one or more organic solvents comprise one or more diols and / or one or more glycol ethers; one or more surfactants, wherein the one or more surfactants are selected from C8-C22 sulfonate surfactants, C8-C22 sulfate surfactants, branched and / or linear ethoxylated sulfate C8-C16 sulfate surfactants, C8-C22 betaine surfactants, C8-C22 sulfobetaine surfactants, C6-C14 dipropionate surfactants, and combinations thereof; optionally, one or more biopolymers; and optionally, one or more alcohols, wherein the one or more alcohols are selected from C6-C16 linear alcohols, C6-C16 branched alcohols, and combinations thereof.

[0009] Various aspects of the present invention also relate to a fire-fighting foam concentrate comprising: silica nanoparticles (e.g., surface-modified silica nanoparticles), wherein the silica nanoparticles comprise silica (SiO2) and a clay component comprising alumina (Al2O3), kaolin (Al2Si2O5(OH)4), or a combination thereof; one or more organic solvents, wherein the one or more organic solvents comprise one or more diols and / or one or more glycol ethers; one or more surfactants, wherein the one or more surfactants are selected from C8-C22 sulfonate surfactants, C8-C22 sulfate surfactants, branched and / or linear ethoxylated sulfate C8-C16 sulfate surfactants, C8-C22 betaine surfactants, C8-C22 sulfobetaine surfactants, dipropionate surfactants, and combinations thereof; optionally, one or more biopolymers; and optionally, one or more alcohols, wherein the one or more alcohols are selected from C6-C16 linear alcohols, C6-C16 branched alcohols, and combinations thereof.

[0010] Certain aspects of the present invention also relate to a fire fighting foam concentrate, the concentrate comprising: surface-modified silica nanoparticles, wherein the silica nanoparticles have a silica (SiO2) content of at least about 50 wt%; one or more organic solvents, wherein the one or more organic solvents comprise one or more diols and / or one or more glycol ethers; an anionic surfactant, comprising: (i) a first anionic surfactant comprising a C8-C22 sulfonate surfactant and / or a C8-C22 sulfate surfactant, and (ii) a second anionic surfactant comprising a branched ethoxylated sulfate C8-C16 sulfate surfactant and / or a linear ethoxylated sulfate C8-C16 surfactant; an amphoteric surfactant comprising a C8-C22 betaine surfactant and a C8-C22 sulfobetaine surfactant and optionally one or more biopolymers; and optionally, one or more alcohols, wherein the one or more alcohols are selected from C6-C16 linear alcohols, C6-C16 branched alcohols, and combinations thereof.

[0011] The present invention also relates to a fire fighting foam solution prepared from any of the concentrates of the present invention.

[0012] Aspects of the present invention also relate to a fire fighting foam composition prepared from any of the concentrates or solutions of the claims of the present invention, wherein the foam composition: meets the non-polar fuel (heptane) fire test in fresh water and sea water according to UL standard 162; and / or exhibits a foam expansion ratio of at least about 5 when a premixed solution containing one or more surface-modified nanoparticles in the range of 30 ppm to 1500 ppm is tested in the laboratory according to UL standard 162; and / or exhibits a foam expansion of at least 9% (or about 10% to about 20%) when tested according to ASTM D1141-98 in sea water and sea water containing a high amount of suspended solids (HSS); and / or meets one or more of the standards listed in the International Civil Aviation Organization (ICAO) Airport Services Manual, 4th Edition (2015) and / or UL 162 Standard (8th Edition) for foam equipment and liquid concentrates.

[0013] Still other aspects of the present invention relate to methods for preparing fire-fighting foam concentrates, the methods comprising: preparing one or more surface-modified nanoparticles by combining one or more silica-containing nanoparticles, a silane group-containing compound, and a graft polymer, wherein the one or more silane groups are selected from alkylsilanes, aminosilanes, acrylic silanes, vinylsilanes, and combinations thereof, and the graft polymer is selected from poly(lactide) (PLA), poly(lactide-co-glycolide) (PLGA) copolymers, poly(ε-caprolactone) (PCL), poly(amino acids), alginates, chitosans, gelatins, albumins, and combinations thereof; and combining the one or more surface-modified nanoparticles with one or more other components of the fire-fighting foam concentrate. The one or more other components are selected from: one or more organic solvents, wherein the one or more organic solvents comprise one or more diols and / or one or more glycol ethers; one or more surfactants, wherein the one or more surfactants are selected from C8-C22 sulfonate surfactants, C8-C22 sulfate surfactants, branched and / or linear ethoxylated sulfate C8-C16 sulfate surfactants, C8-C22 betaine surfactants, C8-C22 sulfobetaine surfactants, C6-C14 alkyliminodipropionate surfactants, and combinations thereof; one or more biopolymers; and one or more alcohols, wherein the one or more alcohols are selected from C6-C16 straight-chain alcohols, C6-C16 branched-chain alcohols, and combinations thereof.

[0014] These and various embodiments of the present invention relate to such fluorine-free, silicon-free, and / or hydrocarbon surfactant-based fire-fighting foams.

[0015] Other objects and features will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The foaming results of the solubility tests of Samples 1-9 described in Example 1 are provided.

[0017] Figure 2 The stability tests of Sample 10 (containing chemically prepared silica nanoparticles) after storage for 15 hours at concentrations of 34000 parts per million (ppm), 3400 ppm, 340 ppm, and 34 ppm (L-R) are provided.

[0018] Figure 3 The results of testing the effect of nanoparticle concentration (340 ppm or 3400 ppm) on the foam expansion (volume) of alkyl-modified nanoparticles (Sample 10) are provided.

[0019] Figure 4Results of the polar fuel (isopropyl alcohol (IPA)) tolerance (foam stability, in seconds (sec)) tests for various samples based on formulation 1 are provided. Detailed Description

[0020] Fire fighting foam concentrates, solutions, and foams that exhibit one or more advantageous properties are described herein. For example, various embodiments of the present invention exhibit improved foam expansion and flash foaming properties. Embodiments of the present invention are also believed to provide improved tolerance to polar fuels (e.g., isopropyl alcohol), including such compositions that do not require the presence of short-chain or long-chain alcohols. Embodiments of the present invention also provide foams that exhibit improved fire test performance when subjected to Underwriters Laboratories (UL) tests. Advantageously, such improved performance has been demonstrated with a variety of water sources and under various conditions.

[0021] Embodiments of the present invention include fire fighting foams (e.g., aqueous film-forming foam (AFFF) and alcohol-resistant aqueous film-forming foam (AR-AFFF)) for extinguishing Class B fires. Various embodiments also include fluorine-free foams.

[0022] In addition to being characterized by their effectiveness, performance characteristics, and components, the compositions of the present invention (e.g., fire fighting foam concentrates, fire fighting foam solutions, and fire fighting foams) can also be characterized as silicone-free, hydrocarbon surfactant-based, and free of any fatty alcohol defoamers.

[0023] Generally, the compositions of the present invention include one or more surface-modified silica nanoparticles and one or more other components selected from: one or more organic solvents, one or more surfactants, one or more biopolymers, and one or more alcohols.

[0024] Nanoparticles

[0025] Without being bound by any particular theory, it is currently believed that the nanoparticles are surface-active, thereby improving the foaming properties of the formulation. Such performance is described herein (including in the working examples) generally and in some cases for formulations in the absence of fatty alcohol defoamers.

[0026] Typically, the nanoparticles described herein contain silica (SiO2) and may optionally contain a clay component. In various embodiments, the nanoparticles have a relatively high silica content of, for example, at least about 50 wt%, at least about 60 wt%, at least about 65 wt%, at least about 70 wt%, at least about 75 wt%, at least about 80 wt%, at least about 85 wt%, at least about 90 wt%, at least about 95 wt%, or at least about 99 wt%. In various embodiments, the nanoparticles consist essentially of silica or consist of silica. It should be understood that when referring to nanoparticles consisting essentially of silica or consisting of silica, this allows for their surface modification to provide surface-modified nanoparticles.

[0027] Suitable clay components for the nanoparticles include alumina (Al2O3), kaolin (Al2Si2O5(OH)4), and combinations thereof.

[0028] In certain embodiments, the silica nanoparticles have an alumina content of at least about 5 wt%, at least about 10 wt%, at least about 20 wt%, at least about 30 wt%, at least about 40 wt%, at least about 50 wt%, at least about 60 wt%, at least about 65 wt%, at least about 70 wt%, at least about 75 wt%, at least about 80 wt%, at least about 85 wt%, at least about 90 wt%, at least about 95 wt%, or at least about 99 wt%.

[0029] In these and other embodiments, the silica nanoparticles can have an alumina content of from about 5 wt% to about 100 wt%, from about 10 wt% to about 90 wt%, from about 20 wt% to about 75 wt%, from about 30 wt% to about 75 wt%, from about 40 wt% to about 75 wt%, from about 50 wt% to about 75 wt%, from about 60 wt% to about 75 wt%, from about 65 wt% to about 75 wt%, from about 70 wt% to about 100 wt%, from about 75 wt% to about 100 wt%, from about 80 wt% to about 100 wt%, from about 85 wt% to about 100 wt%, from about 90 wt% to about 100 wt%, or from about 95 wt% to about 100 wt%.

[0030] When including the clay component(s), in certain embodiments, the silica nanoparticles have a silica content of at least about 5 wt%, at least about 10 wt%, at least about 20 wt%, at least about 30 wt%, at least about 40 wt%, at least about 50 wt%, at least about 60 wt%, at least about 65 wt%, at least about 70 wt%, at least about 75 wt%, at least about 80 wt%, at least about 85 wt%, at least about 90 wt%, at least about 95 wt%, or at least about 99 wt%.

[0031] In these and other embodiments, the silica nanoparticles have a silica content of from about 5 wt% to about 100 wt%, from about 10 wt% to about 90 wt%, from about 20 wt% to about 75 wt%, from about 30 wt% to about 75 wt%, from about 40 wt% to about 75 wt%, from about 50 wt% to about 75 wt%, from about 60 wt% to about 75 wt%, from about 65 wt% to about 75 wt%, from about 70 wt% to about 100 wt%, from about 75 wt% to about 100 wt%, from about 80 wt% to about 100 wt%, from about 85 wt% to about 100 wt%, from about 90 wt% to about 100 wt%, or from about 95 wt% to about 100 wt%.

[0032] As detailed herein, it is currently believed that one or more surface modifications of the nanoparticles provide and / or contribute to one or more advantageous properties of the compositions of the present invention. In certain embodiments, the surface modification involves the presence of one or more functional groups at the surface of the silica-based nanoparticles. Generally, the functional groups are selected from one or more silane groups. Generally, the silane groups are selected from alkylsilanes, aminosilanes, acrylic silanes, vinylsilanes, and combinations thereof.

[0033] In this regard, it should be understood that the proportion of the functional groups (e.g., silanes) providing the surface modification indicates the concentration based on the total weight of the silica nanoparticles including the surface modification. Similarly, the proportions of silica, clay, and alumina listed above can relate to silica-based nanoparticles with and without surface modification.

[0034] (one or more) organic solvents

[0035] Suitable organic solvents include alkyl diols, polyols, and glycol ethers. Exemplary alkyl diols include propylene glycol, butylene glycol, neopentyl glycol, ethylene glycol, 2-methyl-2,4-pentanediol, and combinations thereof. According to certain embodiments, the organic solvent is an alkyl diol selected from propylene glycol, butylene glycol, ethylene glycol, and combinations thereof. In certain embodiments, the organic solvent is butylene glycol. In still other embodiments, the organic solvent is an alkyl diol triol, including, for example, glycerol.

[0036] In addition, according to the present invention, the organic solvent can be a glycol ether. Suitable glycol ethers include propylene, n-butyl glycol ether, dipropylene glycol n-propyl ether, dipropylene glycol n-butyl ether, propylene glycol n-butyl ether, propylene glycol n-propyl ether, tripropylene glycol n-butyl ether, propylene glycol phenyl ether, dipropylene glycol phenyl ether, dipropylene glycol dimethyl ether, propylene glycol methyl ether, propylene glycol methyl ether acetate, dipropylene glycol methyl ether, dipropylene glycol methyl ether acetate, tripropylene glycol methyl ether, ethylene glycol hexyl ether; diethylene glycol hexyl ether; ethylene glycol propyl ether; diethylene glycol phenyl ether, ethylene glycol phenyl ether, poly(oxy-1,2-ethanediyl), α-phenyl-ω-hydroxy, diethylene glycol ethyl ether, diethylene glycol n-butyl ether, ethylene glycol n-butyl ether, butyl carbitol, and combinations thereof.

[0037] In certain embodiments, the glycol ether is selected from propylene glycol, n-butyl glycol ether, butylene glycol, butyl carbitol, and combinations thereof.

[0038] In various embodiments, the organic solvent is selected from glycols, alcohols, glycol ethers, and combinations thereof. In certain embodiments, the composition comprises one, two, or three organic solvents.

[0039] In certain embodiments, the composition comprises one, two, or three glycol and / or glycol ether solvents.

[0040] In various embodiments, the one or more organic solvents are selected from propylene glycol, glycerol, ethylene glycol, butyl carbitol, propylene glycol n-butyl ether, butylene glycol, polyethylene glycol, hexylene glycol, and combinations thereof.

[0041] Typically, the total proportion of the solvent is at least about 2 wt%, at least about 5 wt%, at least about 10 wt%, at least about 15 wt%, at least about 20 wt%, or at least about 25 wt%.

[0042] For example, in certain embodiments, the total proportion of the organic solvent is from about 5 wt% to about 30 wt%, from about 5 wt% to about 15 wt%, or from about 2 wt% to about 15 wt%.

[0043] (One or more) surfactants

[0044] The surfactant component of the composition of the present invention generally comprises one or more anionic surfactants and one or more amphoteric surfactants.

[0045] Suitable anionic surfactants include C8-C22 sulfonate surfactants, C8-C22 sulfate surfactants, and branched and / or linear ethoxylated C8-C16 sulfate surfactants.

[0046] In certain embodiments, the C8-C22 sulfonate surfactant or C8-C22 sulfate surfactant is the only anionic surfactant. In other embodiments, both the C8-C22 sulfonate surfactant or C8-C22 sulfate surfactant and the branched and / or linear ethoxylated sulfate C8-C16 sulfate surfactant are also included.

[0047] Any C8-C22 sulfonate surfactant or C8-C22 sulfate surfactant is typically included at a concentration of from about 0.5 wt% to about 10 wt% (e.g., from about 0.5 wt% to about 7 wt%), from about 1 wt% to about 10 wt%, or from about 1 wt% to about 9 wt%.

[0048] Any branched and / or linear ethoxylated C8-C16 sulfate surfactant is typically present at a concentration of from about 1 wt% to about 10 wt% (e.g., from about 1 wt% to about 8 wt%) or from about 5 wt% to about 20 wt%.

[0049] Suitable zwitterionic surfactants include C8-C22 betaine surfactants and C8-C22 sulfobetaine surfactants.

[0050] Any C8-C22 betaine surfactant is typically included at a concentration of from about 2 wt% to about 25 wt%, from about 2 wt% to about 20 wt%, from about 2 wt% to about 15 wt%, or from about 2 wt% to about 12 wt%.

[0051] Any C8-C22 sulfobetaine surfactant is typically included at a concentration of from about 2 wt% to about 25 wt%, from about 2 wt% to about 20 wt%, from about 2 wt% to about 15 wt%, or from about 2 wt% to about 12 wt%.

[0052] Suitable zwitterionic surfactants include C8-C22 betaine surfactants and C8-C22 sulfobetaine surfactants.

[0053] Other suitable surfactants include dipropionate surfactants.

[0054] Suitable dipropionate surfactants include C6-C14 alkyliminodipropionate surfactants.

[0055] Any C6-C14 alkyliminodipropionate surfactant is present at a concentration of at least about 0.1 wt% or from about 0.1 wt% to about 3 wt%.

[0056] In various embodiments, the composition comprises one or more surfactants selected from C8-C22 sulfonate surfactants, C8-C22 sulfate surfactants, branched and / or linear ethoxylated C8-C16 sulfate surfactants, C8-C22 betaine surfactants, C8-C22 sulfobetaine surfactants, dipropionate surfactants, and combinations thereof.

[0057] In certain other embodiments, the composition comprises a hydrocarbon surfactant selected from C8-C22 sulfonate surfactants, C8-C22 sulfate surfactants, branched and / or linear ethoxylated C8-C16 sulfate surfactants, C8-C22 betaine surfactants, C8-C22 sulfobetaine surfactants, and combinations thereof.

[0058] (One or more) alcohols

[0059] Optionally, the compositions of the present invention may comprise one or more alcohols. Suitable alcohols for use in the compositions of the present invention include straight-chain alcohols (e.g., C6-C16 straight-chain alcohols and C8-C16 straight-chain alcohols), branched-chain alcohols (e.g., C6-C16 branched-chain alcohols and C8-C16 branched-chain alcohols), and combinations thereof. Generally, any straight-chain alcohol, branched-chain alcohol, or combination thereof is present at a concentration of from about 0.3 wt% to about 2.5 wt%, or from about 0.3 wt% to about 2.0 wt% of the concentrate.

[0060] (One or more) biopolymers

[0061] Optionally, the compositions of the present invention may further comprise a biopolymer component. The biopolymer component may include one or more (e.g., two or three) biopolymers, wherein the overall biopolymer component is generally present at a concentration of from about 0.2 wt% to about 2.0 wt%.

[0062] Suitable biopolymers include alginate, gum arabic, agar, carrageenan, gellan gum, guar gum, inulin, konjac, locust bean gum, pectin, tara gum, carboxymethyl cellulose (CMC), xanthan gum, carrageenan, diutan gum, scleroglucan, chitin, modified guar gum, casein, welan gum, and combinations thereof.

[0063] In various embodiments, the biopolymer is selected from diutan gum, xanthan gum, guar gum, welan gum, gellan gum, and combinations thereof.

[0064] Further in accordance with the foregoing, the fire-fighting foam concentrate typically contains an amount of water defined by any one of the following values, an amount defined by any one of the following values as a lower or upper limit, and / or an amount defined by a range defined by two of the following values: about 10 wt%, about 15 wt%, about 20 wt%, about 25 wt%, about 30 wt%, about 35 wt%, about 40 wt%, about 45 wt%, about 50 wt%, about 55 wt%, about 60 wt%, about 65 wt%, about 70 wt%, about 75 wt%, about 80 wt%, about 85 wt%, about 90 wt%, or about 95 wt%.

[0065] Methods for preparing the concentrate

[0066] Various aspects of the present invention relate to methods for preparing a fire-fighting foam concentrate, which include methods for preparing surface-modified silica and / or silica-based nanoparticles.

[0067] The surface-modified nanoparticles are typically prepared by a method involving combining a compound containing a functional group (e.g., a silyl group), a graft polymer, and a suitable nanoparticle.

[0068] Suitable silane groups may be selected from alkylsilanes, aminosilanes, acrylic silanes, vinylsilanes, and combinations thereof. Suitable graft polymers may be selected from poly(lactide) (PLA), poly(lactide-co-glycolide) (PLGA) copolymers, poly(ε-caprolactone) (PCL), poly(amino acids), alginates, chitosan, gelatin, albumin, and combinations thereof.

[0069] To prepare the fire fighting foam concentrate of the present invention, the surface-modified nanoparticles are combined with one or more of the components listed above.

[0070] Uses and properties

[0071] The compositions of the present invention are suitable for use in methods for combating and / or extinguishing Class B fires, wherein the compositions are applied directly or indirectly to Class B fires.

[0072] Various embodiments of the present invention also relate to fire fighting foam solutions containing the fire fighting foam concentrate of the present invention and water.

[0073] Typically, such foam solutions contain at least or about 1 wt%, at least or about 2 wt%, at least or about 3 wt%, at least or about 4 wt%, at least or about 5 wt%, or at least or about 6 wt% of the foam concentrate. That is, the foam solution is typically prepared by diluting the foam concentrate with water, with a dilution ratio (concentrate to water) of 1:99 to 6:94.

[0074] It has been found that incorporating surface-modified nanoparticles improves the polar solvent tolerance of the fire fighting foam prepared from the compositions of the present invention. Accordingly, various aspects of the present invention also include methods for improving the polar fuel (e.g., isopropyl alcohol IPA) tolerance of fire fighting foam, which include incorporating one or more surface-modified nanoparticles into the fire fighting foam concentrate, particularly surface-modified silica-containing or silica-based nanoparticles.

[0075] Advantageously, the compositions of the present invention exhibit one or more desired properties when subjected to various tests, including:

[0076] Meeting the non-polar fuel (heptane) fire test in fresh water and sea water according to UL standard 162; and / or

[0077] Exhibiting a foam expansion ratio of at least about 5 when a premixed solution containing one or more surface-modified nanoparticles in the range of 30 ppm to 1500 ppm is tested in the laboratory according to UL standard 162; and / or

[0078] Exhibiting a foam expansion of at least about 9% (e.g., about 10% to about 20%) when tested according to ASTM D1141-98 in sea water and sea water containing a high amount of suspended solids (HSS); and / or

[0079] Meet one or more of the criteria listed in the International Civil Aviation Organization (ICAO) Airport Services Manual, Fourth Edition (2015) and / or

[0080] Meet the UL 162 standard (8th Edition) for foam equipment and liquid concentrates.

[0081] The invention has been described in detail, and it will be apparent that modifications and variations are possible without departing from the scope of the invention as defined in the appended claims.

[0082] Examples

[0083] The following non-limiting examples are provided to further illustrate the invention.

[0084] Example 1

[0085] 1. Screening of Nanoparticles for Fire-Fighting Foams

[0086] Nanoparticles with different surface grafting groups were studied. As listed in Table 1, the grafting groups included aminosilane, methacrylic silane, and vinyl silane.

[0087] Table 1. Nanoparticle and Surface Grafting Information

[0088] Sample ID Properties 1 Based on aminosilane, powder 2 Based on methacrylic silane, powder 3 Based on vinyl silane, powder 4 Based on alkyl silane, powder 5 Treated with aminosilane, powder 6 Treated with methacrylic silane, powder 7 Fine particle size distribution, powder 8 Calcined sample 7, powder 9 Water-soluble silica dispersion 10 Stable and water-soluble aqueous silica dispersion

[0089] 1.1 Testing the foaming properties, solubility, and stability of the test samples in water. As Figure 1 shown, nanoparticles with aminosilane (Sample 1), methacrylic silane (Sample 2), and vinyl silane (Sample 3) grafting groups had good foaming properties and acceptable dispersibility in fresh water. For the purposes of this study, nanoparticles with alkyl modification (Sample 4) seemed to be too hydrophobic.

[0090] Figure 2 Stable nanoparticles of Sample 10 (alkyl-modified nanoparticles) after storage for 15 hours at various concentrations are shown. Nanoparticle concentrations were 34000 parts per million (ppm), 3400 ppm, 340 ppm, and 34 ppm (left (L)-right (R)).

[0091] 1.2 Using Nanoparticles to Increase Foam Expansion and Drainage Time

[0092] The following table summarizes formulations for testing various foam performance characteristics when also containing surface-modified nanoparticles.

[0093] Table 2. Summary of Foam Formulations Tested with Nanoparticles

[0094]

[0095] The following table provides the results of the 50% drainage times of samples 1 (1.1), 2 (1.2), 3 (1.3), and 5 (1.5) of specified volumes prepared from formulation 1 in Table 2.

[0096] Table 3. Effect of nanoparticles on drainage time

[0097]

[0098] Adding nanoparticles to formulation 1 (the baseline described in Table 2) contributed to the rapid generation of viscous foam (flash foaming) during the blender test. The foam volume or expansion ratio increased correlatively with the nanoparticles used in samples 1.1, 1.2, 1.3, and 1.5. The addition of nanoparticles slightly shortened the 50% drainage time of the foam, but it was still within the reasonable range for fire-fighting foam.

[0099] Figure 3 Results are provided for testing the effect of nanoparticle concentration (340 ppm or 3400 ppm) on the foam expansion (volume) of alkyl-modified nanoparticles (sample 10).

[0100] In fresh water (FW), at low concentration (340 ppm) or high concentration (3400 ppm), the addition of nanoparticles contributed to the rapid generation of viscous foam during the blender test. In seawater (SW), lower foam expansion was observed compared to fresh water. Therefore, it is currently believed that higher nanoparticle concentrations in seawater may be required to provide the desired foam expansion.

[0101] Table 4. Examples of nanoparticles extending foam drainage time

[0102]

[0103] Table 4 shows that amino-silane-based nanoparticles (sample 1) improve the foam quality of formulation 3. The foam expansion volume increased by approximately 2%, while the foam drainage time increased by 371 seconds, representing a 44% improvement.

[0104] 1.3 Interaction with biopolymers with improved IPA tolerance

[0105] Figure 4 Results of the polar fuel (isopropyl alcohol (IPA)) tolerance tests include foams based on formulation 1 and those including samples 1 (1.1), 2 (1.2), 3 (1.3), 5 (1.5), 7 (1.7), and 9 (1.9) indicated in Table 1.

[0106] Specifically, Figure 4Results of the polar fuel (isopropyl alcohol (IPA)) tolerance (foam stability, in seconds (sec)) tests on various samples based on formulation 1 are provided.

[0107] In the fire protection industry, alcohols are typically added to foam concentrates to form a polymeric film over polar fuels to prevent vapor migration. The formulations tested herein do not contain alcohols. Thus, Figure 4 the results in [reference] indicate a novel method for polar fuel fire protection in which it is currently believed that nanoparticles interact with biopolymers to form a polymeric film to prevent vapor migration and thus improve the foam's tolerance to IPA. By adding appropriate nanoparticles, the foam's tolerance time to IPA increased from 48 seconds (baseline) to 631 seconds (1.2).

[0108] The following table provides the results of IPA tolerance tests related to the use of nanoparticles in formulation 2 (base stock).

[0109] Table 5. Effect of Nanoparticles on the IPA Tolerance of Formulation 2

[0110]

[0111]

[0112] These results show an improvement in IPA tolerance related to sample 2.1 (aminosilane-based nanoparticles) and sample 2.9 (aqueous silica dispersion).

[0113] 1.4 Full-Scale Fire Tests with Nanoparticles

[0114] The following results pertain to the use of nanoparticles in formulations for which full-scale fire tests were conducted. According to UL standard 162, formulation 1 containing nanoparticles passed the heptane fire tests in fresh water (FW) and salt water (SW). In comparison, formulation 1 without nanoparticles did not fully expand in hard water with high total suspended solids (TSS) and thus could not be subjected to full-scale fire tests.

[0115] Table 7. Fire Test Results with and without Nanoparticles According to UL Standard

[0116]

[0117] Embodiments

[0118] For further illustration, further and preferred embodiments of the present invention are set forth below.

[0119] Embodiment 1 relates to a fire-fighting foam concentrate, which comprises: surface-modified silica nanoparticles, wherein the silica nanoparticles have a silica (SiO2) content of at least about 50% by weight; one or more organic solvents, wherein the one or more organic solvents comprise one or more diols and / or one or more glycol ethers; one or more surfactants, wherein the one or more surfactants are selected from C8-C22 sulfonate surfactants, C8-C22 sulfate surfactants, branched and / or linear ethoxylated sulfate C8-C16 sulfate surfactants, C8-C22 betaine surfactants, C8-C22 sulfobetaine surfactants, C6-C14 dipropionate surfactants, and combinations thereof; optionally, one or more biopolymers; and optionally, one or more alcohols, wherein the one or more alcohols are selected from C6-C16 linear alcohols, C6-C16 branched alcohols, and combinations thereof.

[0120] Embodiment 2 is the concentrate of Embodiment 1, wherein the silica nanoparticles have a silica content of at least about 60% by weight, at least about 65% by weight, at least about 70% by weight, at least about 75% by weight, at least about 80% by weight, at least about 85% by weight, at least about 90% by weight, at least about 95% by weight, or at least about 99% by weight.

[0121] Embodiment 3 is the concentrate of Embodiment 1, wherein the silica nanoparticles consist essentially of silica.

[0122] Embodiment 4 relates to a fire-fighting foam concentrate, which comprises: surface-modified silica nanoparticles, wherein the silica nanoparticles comprise silica (SiO2) and a clay component comprising alumina (Al2O3), kaolin (Al2Si2O5(OH)4), or a combination thereof; one or more organic solvents, wherein the one or more organic solvents comprise one or more diols and / or one or more glycol ethers; one or more surfactants, wherein the one or more surfactants are selected from C8-C22 sulfonate surfactants, C8-C22 sulfate surfactants, branched and / or linear ethoxylated sulfate C8-C16 sulfate surfactants, C8-C22 betaine surfactants, C8-C22 sulfobetaine surfactants, dipropionate surfactants, and combinations thereof; optionally, one or more biopolymers; and optionally, one or more alcohols, wherein the one or more alcohols are selected from C6-C16 linear alcohols, C6-C16 branched alcohols, and combinations thereof.

[0123] Embodiment 5 relates to the concentrate of Embodiment 4, wherein the silica nanoparticles have an alumina content of at least about 5 wt%, at least about 10 wt%, at least about 20 wt%, at least about 30 wt%, at least about 40 wt%, at least about 50 wt%, at least about 60 wt%, at least about 65 wt%, at least about 70 wt%, at least about 75 wt%, at least about 80 wt%, at least about 85 wt%, at least about 90 wt%, at least about 95 wt% or at least about 99 wt%.

[0124] Embodiment 6 relates to the concentrate of Embodiment 4, wherein the silica nanoparticles have an alumina content of from about 5 wt% to about 100 wt%, from about 10 wt% to about 90 wt%, from about 20 wt% to about 75 wt%, from about 30 wt% to about 75 wt%, from about 40 wt% to about 75 wt%, from about 50 wt% to about 75 wt%, from about 60 wt% to about 75 wt%, from about 65 wt% to about 75 wt%, from about 70 wt% to about 100 wt%, from about 75 wt% to about 100 wt%, from about 80 wt% to about 100 wt%, from about 85 wt% to about 100 wt%, from about 90 wt% to about 100 wt% or from about 95 wt% to about 100 wt%.

[0125] Embodiment 7 relates to the concentrate of Embodiment 5 or 6, wherein the silica nanoparticles have a silica content of at least about 5 wt%, at least about 10 wt%, at least about 20 wt%, at least about 30 wt%, at least about 40 wt%, at least about 50 wt%, at least about 60 wt%, at least about 65 wt%, at least about 70 wt%, at least about 75 wt%, at least about 80 wt%, at least about 85 wt%, at least about 90 wt%, at least about 95 wt% or at least about 99 wt%.

[0126] Embodiment 8 relates to the concentrate of Embodiment 5 or 6, wherein the silica nanoparticles have a silica content of from about 5 wt% to about 100 wt%, from about 10 wt% to about 90 wt%, from about 20 wt% to about 75 wt%, from about 30 wt% to about 75 wt%, from about 40 wt% to about 75 wt%, from about 50 wt% to about 75 wt%, from about 60 wt% to about 75 wt%, from about 65 wt% to about 75 wt%, from about 70 wt% to about 100 wt%, from about 75 wt% to about 100 wt%, from about 80 wt% to about 100 wt%, from about 85 wt% to about 100 wt%, from about 90 wt% to about 100 wt% or from about 95 wt% to about 100 wt%.

[0127] Embodiment 9 relates to the concentrate of any one of the foregoing embodiments, wherein the surface-modified silica nanoparticles comprise one or more silyl groups.

[0128] Embodiment 10 relates to the concentrate of Embodiment 9, wherein the one or more silane groups are selected from alkylsilanes, aminosilanes, acrylic silanes, vinylsilanes, and combinations thereof.

[0129] Embodiment 11 relates to the concentrate of any of the foregoing embodiments, wherein one or more solvents are selected from propylene, n-butyl glycol ether, dipropylene glycol n-propyl ether, dipropylene glycol n-butyl ether, propylene glycol n-butyl ether, propylene glycol n-propyl ether, tripropylene glycol n-butyl ether, propylene glycol phenyl ether, dipropylene glycol phenyl ether, dipropylene glycol dimethyl ether, propylene glycol methyl ether, propylene glycol methyl ether acetate, dipropylene glycol methyl ether, dipropylene glycol methyl ether acetate, tripropylene glycol methyl ether, ethylene glycol hexyl ether; diethylene glycol hexyl ether; ethylene glycol propyl ether; diethylene glycol phenyl ether, ethylene glycol phenyl ether, poly(oxy-1,2-ethanediyl), α-phenyl-ω-hydroxy, diethylene glycol ethyl ether, diethylene glycol n-butyl ether, ethylene glycol n-butyl ether, butyl carbitol, and combinations thereof.

[0130] Embodiment 12 relates to the concentrate of any of the foregoing embodiments, wherein the one or more organic solvents are selected from propylene glycol, glycerol, ethylene glycol, butyl carbitol, propylene glycol n-butyl ether, butylene glycol, polyethylene glycol, hexylene glycol, and combinations thereof.

[0131] Embodiment 13 relates to the concentrate of any of the foregoing embodiments, wherein one or more solvents account for at least about 2 wt%, at least about 5 wt%, at least about 10 wt%, at least about 15 wt%, at least about 20 wt%, or at least about 25 wt% of the concentrate.

[0132] Embodiment 14 relates to the concentrate of any of the foregoing embodiments, wherein one or more solvents account for about 5 wt% to about 30 wt%, about 5 wt% to about 15 wt%, or about 2 wt% to about 15 wt% of the concentrate.

[0133] Embodiment 15 relates to the concentrate of any of the foregoing embodiments, wherein the concentrate contains a hydrocarbon surfactant selected from C8-C22 sulfonate surfactants, C8-C22 sulfate surfactants, branched and / or linear ethoxylated sulfate C8-C16 sulfate surfactants, C8-C22 betaine surfactants, C8-C22 sulfobetaine surfactants, and combinations thereof.

[0134] Embodiment 16 relates to the concentrate of any of the foregoing embodiments, wherein the concentrate contains a C8-C22 sulfonate surfactant and / or a C8-C22 sulfate surfactant at a concentration of about 0.5 wt% to about 10 wt%, about 0.5 wt% to about 7 wt%, about 1 wt% to about 10 wt%, or about 1 wt% to about 9 wt%.

[0135] Embodiment 17 relates to a concentrate according to any one of the foregoing embodiments, wherein the concentrate comprises a branched and / or linear ethoxylated C8-C16 sulfate surfactant at a concentration of from about 1 wt% to about 10 wt%, from about 1 wt% to about 8 wt% or from about 5 wt% to about 20 wt%.

[0136] Embodiment 18 relates to a concentrate according to any one of the foregoing embodiments, wherein the concentrate comprises a C8-C22 betaine surfactant at a concentration of from about 2 wt% to about 25 wt%, from about 2 wt% to about 20 wt%, from about 2 wt% to about 15 wt% or from about 2 wt% to about 12 wt%.

[0137] Embodiment 19 relates to a concentrate according to any one of the foregoing embodiments, wherein the concentrate comprises a C8-C22 sulfobetaine surfactant at a concentration of from about 2 wt% to about 25 wt%, from about 2 wt% to about 20 wt%, from about 2 wt% to about 15 wt% or from about 2 wt% to about 12 wt%.

[0138] Embodiment 20 relates to a concentrate according to any one of the foregoing embodiments, wherein the concentrate comprises a C6-C14 alkyliminodipropionate surfactant at a concentration of at least about 0.1 wt% or from about 0.1 wt% to about 3 wt%.

[0139] Embodiment 21 relates to a concentrate according to any one of the foregoing embodiments, wherein the one or more biopolymers are selected from alginate, gum arabic, agar, carrageenan, gellan gum, guar gum, inulin, konjac, locust bean gum, pectin, tara gum, carboxymethyl cellulose (CMC), xanthan gum, diutan gum, scleroglucan, chitin, modified guar gum, casein, welan gum, and combinations thereof.

[0140] Embodiment 22 relates to a concentrate according to any one of the foregoing embodiments, wherein the one or more biopolymers are selected from diutan gum, xanthan gum, guar gum, welan gum, gellan gum, and combinations thereof.

[0141] Embodiment 23 relates to a concentrate according to any one of the foregoing embodiments, wherein the one or more biopolymers are present in the concentrate in an amount of from about 0.2 wt% to about 2.0 wt%.

[0142] Embodiment 24 relates to a concentrate according to any one of the foregoing embodiments, wherein the one or more alcohols are present in the concentrate in an amount of from about 0.3 wt% to about 0.25 wt% or from about 0.3 wt% to about 2.0 wt%.

[0143] Embodiment 25 relates to a fire-fighting foam solution composition, the foam solution being prepared by diluting any one of the concentrates of the foregoing claims with water.

[0144] Embodiment 26 relates to a fire-fighting foam solution composition, the foam solution comprising any one of the concentrates of the foregoing embodiments and water.

[0145] Embodiment 27 relates to a fire-fighting foam composition prepared from any one of the concentrates or solutions of the embodiments of the present invention, wherein the foam composition: meets the non-polar fuel (heptane) fire test in fresh water and sea water according to UL Standard 162; and / or exhibits a foam expansion ratio of at least about 5 when a premixed solution containing one or more surface-modified nanoparticles in the range of 30 ppm to 1500 ppm is tested in the laboratory according to UL Standard 162; and / or exhibits a foam expansion of at least about 9% (or about 10% to about 20%) when tested according to ASTM D1141-98 in sea water and sea water containing a high amount of suspended solids (HSS); and / or meets one or more of the criteria listed in the International Civil Aviation Organization (ICAO) Airport Services Manual, 4th Edition (2015) and / or UL 162 Standard (8th Edition) for foam equipment and liquid concentrates.

[0146] Embodiment 28 relates to a method for improving the tolerance of a fire-fighting foam to a polar solvent (isopropyl alcohol), the method comprising: introducing surface-modified silica nanoparticles into a fire-fighting foam concentrate, wherein the fire-fighting foam concentrate comprises: one or more organic solvents, wherein the one or more organic solvents comprise one or more diols and / or one or more diol ethers; one or more surfactants, wherein the one or more surfactants are selected from C8-C22 sulfonate surfactants, C8-C22 sulfate surfactants, branched and / or linear ethoxylated sulfate C8-C16 sulfate surfactants, C8-C22 betaine surfactants, C8-C22 sulfobetaine surfactants, C6-C14 alkyl-imino dipropionate surfactants, and combinations thereof; optionally, one or more biopolymers; and optionally, one or more alcohols, wherein the one or more alcohols are selected from C6-C16 linear alcohols, C6-C16 branched alcohols, and combinations thereof.

[0147] Embodiment 29 relates to a method for preparing a fire-fighting foam concentrate, the method comprising: preparing one or more surface-modified nanoparticles by combining one or more silica-containing nanoparticles, a silane group-containing compound, and a graft polymer, wherein the one or more silane groups are selected from alkylsilanes, aminosilanes, acrylic silanes, vinylsilanes, and combinations thereof, and the graft polymer is selected from poly(lactide) (PLA), poly(lactide-co-glycolide) (PLGA) copolymer, poly(ε-caprolactone) (PCL), poly(amino acids), alginate, chitosan, gelatin, albumin, and combinations thereof; and combining the one or more surface-modified nanoparticles with one or more other components of the fire-fighting foam concentrate, the one or more other components being selected from: one or more organic solvents, wherein the one or more organic solvents comprise one or more diols and / or one or more diol ethers; one or more surfactants, wherein the one or more surfactants are selected from C8-C22 sulfonate surfactants, C8-C22 sulfate surfactants, branched and / or linear ethoxylated sulfate C8-C16 sulfate surfactants, C8-C22 betaine surfactants, C8-C22 sulfobetaine surfactants, C6-C14 alkyliminodipropionate surfactants, and combinations thereof; one or more biopolymers; and one or more alcohols, wherein the one or more alcohols are selected from C6-C16 linear alcohols, C6-C16 branched alcohols, and combinations thereof.

[0148] Example embodiments have been provided so as to render the disclosure thorough and to convey the full scope to those skilled in the art. Numerous specific details are set forth such as examples of specific components, assemblies, and methods in order to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms, and that neither should they be construed to limit the scope of the disclosure. In some example embodiments, well-known methods, well-known device structures, and well-known technologies have not been described in detail.

[0149] When introducing elements of the present disclosure or (one or more) preferred embodiments thereof, the articles “a,” “an,” “the,” and “said” are intended to mean that there is one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Method steps, processes, and operations described herein should not be construed as necessarily requiring execution in the particular order discussed or illustrated, unless specifically identified as an order of execution. It should also be understood that additional or alternative steps may be employed.

[0150] Although terms such as first, second, third, etc. may be used herein to describe various elements, components, members, and / or sections, these elements, components, members, and / or sections should not be limited by these terms. These terms may be used only to distinguish one element, component, member, or section from another. Unless the context clearly indicates otherwise, when used herein, terms such as "first," "second," and other numerical terms do not imply a sequence or order. Thus, without departing from the teachings of the exemplary embodiments, the first element, component, member, or section discussed below may be referred to as the second element, component, member, or section.

[0151] In view of the foregoing, it can be seen that several objectives of the present invention are achieved and other advantageous results are obtained.

[0152] Since various changes may be made to the above products and methods without departing from the scope of the present invention, it is intended that all matter contained above be interpreted accordingly.

Claims

1. A fire-fighting foam concentrate, the concentrate comprising: Surface-modified silica nanoparticles, wherein the silica nanoparticles have a silica (SiO2) content of at least about 50 wt%; One or more organic solvents, wherein the one or more organic solvents comprise one or more diols and / or one or more glycol ethers; Anionic surfactants, which comprise: (i) a first anionic surfactant comprising a C8-C22 sulfonate surfactant and / or a C8-C22 sulfate surfactant; and (ii) a second anionic surfactant comprising a branched ethoxylated sulfate C8-C16 sulfate surfactant and / or a linear ethoxylated sulfate C8-C16 surfactant; Amphoteric surfactants, which comprise C8-C22 betaine surfactants and C8-C22 sulfobetaine surfactants, and Optionally, one or more biopolymers; and Optionally, one or more alcohols, wherein the one or more alcohols are selected from C6-C16 linear alcohols, C6-C16 branched alcohols, and combinations thereof.

2. The concentrate according to claim 1, wherein the silica nanoparticles have a silica content of at least about 60 wt%, at least about 65 wt%, at least about 70 wt%, at least about 75 wt%, at least about 80 wt%, at least about 85 wt%, at least about 90 wt%, at least about 95 wt%, or at least about 99 wt%.

3. The concentrate according to claim 1, wherein the silica nanoparticles consist essentially of silica.

4. The concentrate according to claim 1, wherein the surface-modified silica nanoparticles further comprise a clay component, the clay component comprising alumina (Al2O3), kaolin (Al2Si2O5(OH)4), or a combination thereof.

5. The concentrate according to claim 1, wherein the silica nanoparticles have a silica content of from about 50 wt% to about 75 wt%, from about 60 wt% to about 75 wt%, from about 65 wt% to about 75 wt%, from about 70 wt% to about 100 wt%, from about 75 wt% to about 100 wt%, from about 80 wt% to about 100 wt%, from about 85 wt% to about 100 wt%, from about 90 wt% to about 100 wt%, or from about 95 wt% to about 100 wt%.

6. The concentrate according to claim 1, wherein the surface-modified silica nanoparticles comprise one or more silyl groups.

7. The concentrate according to claim 6, wherein the one or more silyl groups are selected from alkylsilanes, aminosilanes, acrylic silanes, vinylsilanes, and combinations thereof.

8. The concentrate according to claim 1, wherein the surface-modified silica nanoparticles comprise one or more alkyl groups.

9. The concentrate according to claim 1, wherein the one or more solvents are selected from propylene, n-butyl glycol ether, dipropylene glycol n-propyl ether, dipropylene glycol n-butyl ether, propylene glycol n-butyl ether, propylene glycol n-propyl ether, tripropylene glycol n-butyl ether, propylene glycol phenyl ether, dipropylene glycol phenyl ether, dipropylene glycol dimethyl ether, propylene glycol methyl ether, propylene glycol methyl ether acetate, dipropylene glycol methyl ether, dipropylene glycol methyl ether acetate, tripropylene glycol methyl ether, ethylene glycol hexyl ether; diethylene glycol hexyl ether; ethylene glycol propyl ether; diethylene glycol phenyl ether, ethylene glycol phenyl ether, poly(oxy-1,2-ethanediyl), α-phenyl-ω-hydroxy, diethylene glycol ethyl ether, diethylene glycol n-butyl ether, ethylene glycol n-butyl ether, butyl carbitol, and combinations thereof.

10. The concentrate according to claim 1, wherein the one or more organic solvents are selected from propylene glycol, glycerol, ethylene glycol, butyl carbitol, propylene glycol n-butyl ether, butylene glycol, polyethylene glycol, hexylene glycol, and combinations thereof.

11. The concentrate according to claim 1, wherein the one or more solvents account for at least about 2 wt%, at least about 5 wt%, at least about 10 wt%, at least about 15 wt%, at least about 20 wt%, or at least about 25 wt% of the concentrate.

12. The concentrate according to claim 1, wherein the one or more solvents account for about 5 wt% to about 30 wt%, about 5 wt% to about 15 wt%, or about 2 wt% to about 15 wt% of the concentrate.

13. The concentrate according to claim 1, wherein the anionic surfactant comprises a C8-C22 sulfonate surfactant and a branched ethoxylated C8-C16 sulfate surfactant, and wherein the concentrate comprises the anionic surfactant in a proportion of about 0.5 wt% to about 10 wt%.

14. The concentrate according to claim 1, wherein the anionic surfactant comprises a C8-C22 sulfonate surfactant and a linear ethoxylated sulfate C8-C16 surfactant, and wherein the concentrate comprises the anionic surfactant in a proportion of about 0.5 wt% to about 10 wt%.

15. The concentrate according to claim 1, wherein the anionic surfactant comprises a C8-C22 sulfate surfactant and a branched ethoxylated C8-C16 sulfate surfactant, and wherein the concentrate comprises the anionic surfactant in a proportion of about 0.5 wt% to about 10 wt%.

16. The concentrate according to claim 1, wherein the anionic surfactant comprises a C8-C22 sulfate surfactant and a linear ethoxylated C8-C16 surfactant, and wherein the concentrate comprises the anionic surfactant in a proportion of about 0.5 wt% to about 10 wt%.

17. The concentrate according to claim 1, wherein the concentrate comprises the C8-C22 betaine surfactant at a concentration of about 2 wt% to about 15 wt%.

18. The concentrate according to claim 1, wherein the concentrate comprises the C8-C22 sulfobetaine surfactant at a concentration of about 2 wt% to about 15 wt%.

19. The concentrate according to claim 1, wherein the concentrate further comprises a C6-C14 alkyliminodipropionate surfactant at a concentration of from about 0.1 wt% to about 3 wt%.

20. The concentrate according to claim 1, the concentrate comprising one or more biopolymers, wherein the one or more biopolymers are selected from alginate, gum arabic, agar, carrageenan, gellan gum, guar gum, inulin, konjac, locust bean gum, pectin, tara gum, carboxymethyl cellulose (CMC), xanthan gum, diutan gum, scleroglucan, chitin, modified guar gum, casein, welan gum, and combinations thereof, and wherein the one or more biopolymers account for from about 0.2 wt% to about 2.0 wt% of the concentrate.

21. The concentrate according to claim 20, wherein the one or more biopolymers are selected from diutan gum, xanthan gum, guar gum, welan gum, gellan gum, and combinations thereof.

22. The concentrate according to claim 1, the concentrate comprising one or more alcohols, wherein the one or more alcohols comprise C8-C16 straight-chain alcohols and / or C8-C16 branched-chain alcohols, and account for from about 0.3 wt% to about 0.25 wt% or from about 0.3 wt% to about 2.0 wt% of the concentrate.

23. The concentrate according to claim 1, wherein the concentrate is fluorine-free, silicone-free, and / or free of any fatty alcohol defoamer.

24. A fire-fighting foam solution composition, the foam solution being prepared by diluting any one of the concentrates according to the preceding claims with water.

25. A fire-fighting foam solution composition, the foam solution comprising any one of the concentrates according to the preceding claims and water.

26. A fire-fighting foam composition prepared from any one of the concentrates or solutions according to the claims of the present invention, wherein the foam composition: Meets the non-polar fuel (heptane) fire test in fresh water and sea water according to UL Standard 162; and / or Exhibits a foam expansion ratio of at least about 5 when a premixed solution containing one or more surface-modified nanoparticles in the range of 30 ppm to 1500 ppm is tested in the laboratory according to UL Standard 162; and / or Exhibits a foam expansion of at least about 9% (or from about 10% to about 20%) when tested according to ASTM D1141-98 in sea water and sea water containing a high amount of suspended solids (HSS); and / or Meets the International Civil Aviation Organization (ICAO) Airport Services Manual, 4th Edition (2015) and / or One or more of the criteria listed in UL 162 Standard (8th Edition) for foam equipment and liquid concentrates.

27. A method for improving the tolerance of fire-fighting foam to polar solvents containing isopropanol, the method comprising: Introducing surface-modified silica nanoparticles into a fire-fighting foam concentrate, wherein the fire-fighting foam concentrate comprises: One or more organic solvents, wherein the one or more organic solvents comprise one or more diols and / or one or more diol ethers; One or more surfactants, wherein the one or more surfactants are selected from C8-C22 sulfonate surfactants, C8-C22 sulfate surfactants, branched and / or linear ethoxylated sulfate C8-C16 sulfate surfactants, C8-C22 betaine surfactants, C8-C22 sulfobetaine surfactants, C6-C14 alkyliminodipropionate surfactants, and combinations thereof; Optionally, one or more biopolymers; and Optionally, one or more alcohols, wherein the one or more alcohols are selected from C6-C16 linear alcohols, C6-C16 branched alcohols, and combinations thereof.

28. A method for preparing a fire-fighting foam concentrate, the method comprising: Preparing one or more surface-modified nanoparticles by combining one or more silica-containing nanoparticles, a compound containing a silane group, and a graft polymer, wherein the one or more silane groups are selected from alkylsilanes, aminosilanes, acrylic silanes, vinylsilanes, and combinations thereof, and the graft polymer is selected from poly(lactide) (PLA), poly(lactide-co-glycolide) (PLGA) copolymer, poly(ε-caprolactone) (PCL), poly(amino acids), alginate, chitosan, gelatin, albumin, and combinations thereof; and Combining the one or more surface-modified nanoparticles with one or more other components of the fire-fighting foam concentrate, wherein the one or more other components are selected from: One or more organic solvents, wherein the one or more organic solvents comprise one or more diols and / or one or more diol ethers; One or more surfactants, wherein the one or more surfactants are selected from C8-C22 sulfonate surfactants, C8-C22 sulfate surfactants, branched and / or linear ethoxylated sulfate C8-C16 sulfate surfactants, C8-C22 betaine surfactants, C8-C22 sulfobetaine surfactants, C6-C14 alkyliminodipropionate surfactants, and combinations thereof; Optionally, one or more biopolymers; and Optionally, one or more alcohols, wherein the one or more alcohols are selected from C6-C16 linear alcohols, C6-C16 branched alcohols, and combinations thereof.

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