CN116782988A

CN116782988A - Filter medium

Info

Publication number: CN116782988A
Application number: CN202180084952.4A
Authority: CN
Inventors: 泰勒·蒙科; 弗兰克·库萨特
Original assignee: Ahlstrom Corp
Current assignee: Ahlstrom Corp
Priority date: 2020-12-18
Filing date: 2021-12-17
Publication date: 2023-09-19

Abstract

A filter media suitable for filtering a fluid is provided. The filter media includes a first component having Al ₂ O ₃ A core in an amount of at least 10 wt% and a nano alumina coating at least partially covering the core.

Description

Filter medium

Technical Field

The present invention relates to a filter medium, more particularly to a filter medium comprising an Al-containing material which has been coated with nano-alumina ₂ O ₃ A particulate or fibrous filter medium useful for passing a fluid such as waterContaminants such as positively charged species are filtered.

Introduction to the invention

Purification of water for human consumption, industrial water and waste treatment water is a worldwide problem. Most water purification techniques involve some form of mechanical filtration or size exclusion. These techniques typically involve the use of submicron filters to remove pathogens (such as bacteria and viruses), metals, and particulates from water.

A wide variety of water filtration media are known. These typically include particles comprising one or more of activated carbon, zeolite, metal oxides, clay, diatomaceous earth, and other materials, which are typically dispersed in a polymeric binder that holds the particles in place during filtration and reduces entrainment of the particles into the filtered water.

The prior art filter media comprises a substrate with a nano alumina (alumina/aluminum hydroxide) coating. For example, US 9,309,131 describes powdered siliceous components (including diatomaceous earth, perlite, talc, vermiculite, sand and calcined composites) on which nano alumina has been deposited as a suitable adsorbent for purifying water. The silicon-containing component has been defined as a material having silicon dioxide as the main component, typically having a silicon dioxide content of at least 40% by weight. On the other hand, US 2016/024373 A1 discloses a sintered ceramic filter comprising fibers of metal oxide obtained by electrospinning, and powdered nano-alumina incorporated in or coated on the fibers. While these types of filter media are known to moderately remove contaminants from water, their performance still leaves room for improvement.

Disclosure of Invention

According to a first aspect of the present invention, there is provided a filter medium comprising a first component having Al ₂ O ₃ A core in an amount of at least 10 wt% and a nano alumina coating at least partially coating the core.

According to another aspect of the present invention, there is provided a filter medium comprising a first component having Al ₂ O ₃ A core in an amount of at least 10 wt% and a nano alumina coating at least partially coating the core, wherein the core is in the form of fibers, plates or powder particles, and wherein the filter medium further comprises matrix fibers as a second component.

Al of core ₂ O ₃ The content may be at least 20 wt%, preferably at least 40 wt%, preferably at least 60 wt%, or preferably at least 80 wt%.

SiO of the core ₂ The content may be less than 60 wt%, preferably less than 40 wt%, preferably less than 20 wt%.

The core may be in the form of a fiber, a board or powder particles.

The core may be selected from one or more of alumina powder, alumina fibers, crystalline aluminosilicate and amorphous aluminosilicate.

The average size of the core may be from 0.1 μm to 50 μm, preferably from 0.1 μm to 30 μm, more preferably from 0.1 μm to 15 μm. When the core is a powder particle, the average particle size may preferably be 1 μm to 30 μm. When the core is a fiber, the average diameter of the fiber may preferably be 1 μm to 5 μm. When the core is a plate, the average planar dimension of the plate may be 0.1 μm to 50 μm.

The first component may comprise from 10 wt% to 99 wt%, preferably from 50 wt% to 95 wt%, or more preferably from 70 wt% to 90 wt% of the nano-alumina coating.

The core may comprise from 1% to 90% by weight of the first component, preferably from 5% to 50% by weight, more preferably from 10% to 30% by weight.

The filter media may further comprise a second component comprising matrix fibers. The matrix fibers may preferably be selected from one or more of cellulose fibers, synthetic fibers and fibrillated fibers.

The matrix fibers may be at least partially coated with nano-alumina.

The nano-alumina may be present in the filter medium in an amount of 20 wt.% to 70 wt.%, preferably 30 wt.% to 60 wt.%, preferably 40 wt.% to 50 wt.%, based on the total weight of the filter medium.

The filter media may comprise less than 1% by weight glass fibers, preferably less than 0.1% by weight glass fibers.

The mass ratio of the first component to the second component of the filter medium may be from 1:1 to 1:10, preferably from 1:3 to 1:6.

The mass ratio of the first component to the second component of the filter medium may be from 4:1 to 1:10.

According to a second aspect of the present invention there is provided a method of manufacturing a first component for a filter medium as defined above, the method comprising at least partially coating a core with nano-alumina.

According to a third aspect of the present invention there is provided a method of manufacturing a filter medium as defined above, the method comprising:

(a) Forming a wet laid (wet laid) sheet from a fibrous slurry comprising a first component; and

(b) The wet laid sheet is dried to obtain a filter medium.

The method may include coating the core with nano-alumina to form the first component.

The fiber slurry may also include matrix fibers and/or binder fibers.

According to another aspect of the present invention there is provided a method of manufacturing a filter medium as defined above, the method comprising:

(a) Forming a wet laid sheet from a fibrous slurry comprising a first component and a second component; and

(b) The wet laid sheet is dried to obtain a filter medium.

The method may include at least partially coating the matrix fibers and/or the binder fibers with nano-alumina.

The method may include simultaneously coating the core, matrix fibers, and/or binder fibers with nano-alumina.

The method may include coating the core, matrix fibers, and/or binder fibers sequentially with nano-alumina.

According to a fourth aspect of the present invention there is provided a method of filtering a fluid, the method comprising passing the fluid through a filter medium as defined above.

The invention will be better understood on the basis of the following examples, which are given by way of illustration and should not be interpreted in a limiting manner, and of the accompanying drawings.

Drawings

FIG. 1 is a graph showing the relative ability of four different filter media to filter erythrosin dye from water. Each filter medium comprises a different glass type having a different alumina content.

FIG. 2 is a graph showing the relative ability of five different filter media to filter erythrosin dye from water. Each filter medium comprises a different core material.

Detailed Description

As used herein and in the appended claims, the following terms are intended to have the following definitions unless the content requires otherwise.

Variations such as "comprises" or "comprising" are to be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

"nanometer alumina" refers to aluminum hydroxide oxide [ AlO (OH)]And aluminum hydroxide [ Al (OH) ₃ ]Obtained by reacting aluminum metal with an aqueous alkaline solution such as NaOH, KOH or ammonium hydroxide.

"fiber" is a high aspect ratio fiber or filament structure having a length to diameter.

The "mass ratio" of the two components a and B relative to each other can be expressed in the form: component a/component B. This refers to the ratio of the weight of component a to the weight of component B. Component a and component B may be elemental (such as Al, si, na, etc.) or chemical species (such as Al ₂ O ₃ 、SiO ₂ 、Na ₂ O, etc.). The mass ratio can be converted to a molar ratio by dividing the mass of the components by their molecular weight.

"staple fibers" refers to fibers that naturally have or have been cut or further processed into definite, relatively short segments or individual lengths.

"fibrous" refers to a material consisting essentially of fibers and/or staple fibers.

The term "nonwoven" or "web" refers to a collection of fibers and/or staple fibers in the form of a web or mat that are randomly interlocked, entangled, and/or bonded to one another to form a self-supporting structural element.

"synthetic fibers" refers to fibers made from fiber forming materials including polymers synthesized from chemical compounds, modified or converted natural polymers, and siliceous (glass) materials. Such fibers may be produced by conventional melt spinning, solution spinning, solvent spinning, and similar filament production techniques.

The present disclosure provides filter media suitable for use in a variety of industrial and domestic fluid purification applications. The filter media are particularly useful for removing impurities such as heavy metals (e.g., arsenic, antimony, cadmium, cobalt, copper, iron, lead and lead oxides, mercury, nickel, palladium, selenium, silver, thallium, tin and organotin, and zinc), dyes, oils, biological materials (e.g., bacteria, viruses, natural organic substances, vesicles and cell debris), and trace amounts of drugs from fluids such as water.

The filter medium includes a first component having Al ₂ O ₃ A core in an amount of at least 10 wt% or preferably at least 20 wt%. Al of core ₂ O ₃ The content may be at least 15 wt%, 25 wt%, 30 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt% or 100 wt%. In some embodiments, the Al of the core ₂ O ₃ The content is preferably at least 60 wt%, preferably at least 80 wt%, or preferably 100 wt%. In some embodiments, the Al of the core ₂ O ₃ The content is 47 to 52 wt%, 70 to 100 wt% or 95 to 97 wt%.

SiO of the core ₂ The content may be less than 65 wt%, 60 wt%, 55 wt%, 50 wt%, 45 wt%, 40 wt%, 35 wt%, 30 wt%, 25 wt%, 20 wt%, 15 wt%, 10 wt%, 5 wt%, 1 wt% or 0.1 wt%. In some embodiments, the SiO of the core ₂ The content is preferably less than 40 wt%, or preferably less than20% by weight.

The core may comprise a material selected from alumina (Al ₂ O ₃ 、Al ₂ O or AlO), alumina (aluminum), crystalline aluminosilicate and amorphous aluminosilicate. The core may be in the form of a fiber, a plate, a powder particle, a crystalline particle, an amorphous particle, or a porous particle (e.g., microporous or mesoporous Kong Keli). In some embodiments, the core may be selected from Al ₂ O ₃ Powder, al ₂ O ₃ Fibers (e.g., polycrystalline cotton), powdered aluminosilicates (such as zeolite), aluminosilicate fibers (e.g., ceramic fibers such as refractory ceramic fibers), aluminosilicate glass fibers, and E-glass (aluminoborosilicate glass having an alkali oxide content of less than 1% w/w) fibers. The E-glass core may have an alumina content of greater than 10 wt.%, or from 10 to 20 wt.%, preferably from 13 to 16 wt.%.

The average size of the core may be from 0.1 μm to 50 μm, preferably from 0.1 μm to 30 μm, more preferably from 0.1 μm to 15 μm. When the core is in the form of powder particles, the average size may preferably be 1 μm to 30 μm, and when the core is in the form of fibers, the average diameter of the fibers may preferably be 1 μm to 5 μm.

The core may comprise from 1% to 90% by weight of the first component, preferably from 5% to 50% by weight, more preferably from 10% to 30% by weight. In some embodiments, the core may comprise 40% to 80% by weight of the first component, preferably 50% to 70% by weight.

The core may comprise at least 1 wt%, preferably at least 5 wt%, most preferably from 5 wt% to 70 wt%, even more preferably from 5 wt% to 50 wt%, of the filter medium, based on the total weight of the filter medium.

In some embodiments, the core may have a high alumina (Al ₂ O ₃ ) The characteristics of content and low silica content and therefore may be defined as not glass. The glass generally has greater than 50% or even greater than 60% SiO ₂ Is characterized by the silica content of (2). Furthermore, although some forms of glass contain alumina, the amount of alumina in the glass is generally low (i.e., less than 10% in most cases, and low in almost all cases)At 20%). Since the alumina content of the core of the first component may be at least 10%, preferably at least 20% by weight and the silica content may be less than 60% of two, it may not be defined as glass and thus may be used in filtration media in jurisdictions where glass-containing water filtration media are prohibited. Accordingly, the filter media may comprise less than 1% by weight glass fibers or particles, preferably less than 0.1% by weight glass fibers or particles, or even no detectable glass fibers or particles.

The nano-alumina coating at least partially coats the core and preferably substantially completely coats the core. The nano-alumina may be present in the filter medium in an amount of 20 wt.% to 70 wt.%, preferably 25 wt.% to 65 wt.%, 30 wt.% to 60 wt.%, 35 wt.% to 55 wt.%, or 40 wt.% to 50 wt.%, based on the total weight of the filter medium.

The first component may comprise from 10 wt% to 99 wt%, preferably from 50 wt% to 95 wt%, or preferably from 70 wt% to 90 wt% of the nano-alumina coating.

In use, the nano alumina coating will be positively charged when immersed in water (such as when water is passed through the filter medium). The positive charge electrostatically attracts and entraps negatively charged impurities in the water, thereby allowing the water to be purified by the filter medium.

It has been found that filter media of the present disclosure in which the alumina content of the core is higher exhibit superior filtration performance compared to filter media in which the alumina content of the core is lower. Without wishing to be bound by theory, it is believed that this improvement occurs because increasing the alumina content of the core increases the positive charge in the nano-alumina coating.

The filter media may further comprise a second component comprising matrix fibers for structural support. The matrix fibers may be selected from one or more of cellulose fibers, synthetic fibers, and fibrillated fibers. Fibrillated fibers are generally synthetic or cellulosic fibers that are mechanically treated to produce fibrils. If fibrillated cellulose fibers and fibrillated synthetic fibers are present, the fibrillated cellulose fibers are counted as cellulose fibers and the fibrillated synthetic fibers are counted as synthetic fibers. The matrix fibers can be mixed with the first component to produce a nonwoven filter medium. The matrix fibers may be at least partially coated with nano-alumina.

The filter media may comprise 5 to 70 wt%, preferably 20 to 50 wt% of the matrix fibers based on the total weight of the filter media.

The filter media may comprise 5 to 70 wt%, preferably 5 to 50 wt% cellulose fibers, based on the total weight of the filter media.

The filter media may comprise at least 80 wt%, preferably at least 90 wt%, or more preferably at least 95 wt% synthetic matrix fibers, based on the total weight of the matrix fibers. The synthetic matrix fibers may be selected from one or more of synthetic polymer fibers, modified or converted natural polymer fibers, or silicon-containing (glass) fibers. Exemplary fibers include polyesters (e.g., polyethylene terephthalate, such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc.), polyolefins (e.g., polyethylene, polypropylene, etc.), polyacrylonitrile (PAN), etc.), and polyamides (nylons, e.g., nylon 6, nylon 6,12, etc.).

The filter media may comprise at least 80 wt%, preferably at least 85 wt%, cellulose fibers based on the total weight of the matrix fibers. The cellulose fibers may be selected from one or more of softwood fibers, hardwood fibers, plant fibers, and regenerated cellulose fibers (also known as man-made cellulose fibers, such as Lyocell fibers or viscose (Rayon) fibers). At least a portion of the cellulose fibers may be fibrillated.

According to another alternative, the matrix fibers may comprise a mixture of cellulosic fibers and synthetic fibers. The synthetic fibers are present in the filter medium in an amount up to 50 wt%, preferably between 10 wt% and 30 wt%, or preferably between 15 wt% and 25 wt%, of the total weight of matrix fibers in the filter medium.

The filter media may be a nonwoven filter media. The nonwoven filter media can be corrugated, cut, folded, pleated, and assembled into a final filtration product for use.

To enhance bonding between the first component and the matrix fibers, the filter media may include binder fibers, such as those made fromFabricated->PET microfibers. If binder fibers are present, the binder fibers are counted as matrix fibers. The binder fibers include thermoplastic portions that may soften or melt during processing of the filter media (e.g., during the calendaring step). The binder fibers may be monocomponent or bicomponent. The bicomponent thermoplastic fiber may comprise a thermoplastic core fiber surrounded by a fusible coating of a thermoplastic polymer having a melting point lower than the melting point of the core.

The filter media may include a polymeric binder that may be added to enhance the overall cohesiveness of the components of the filter media. The filter media may include polymeric binders such as styrene acrylic acid, acrylic acid copolymers, polyethylene vinyl chloride, styrene butadiene rubber, polystyrene acrylate, polyacrylate, polyvinyl chloride, polynitrile, polyvinyl acetate, polyvinyl alcohol derivatives, starch polymers, phenolic resins, and combinations thereof, including aqueous and solvent borne. In some cases, the polymeric binder may be in the form of a latex (e.g26450 Such as a water-based latex emulsion.

The filter media may also include one or more additive components. The additive component may be selected from: wet strength resins, such as polyamide epichlorohydrin (PAE) resins (e.gGHP resin) that may be added to enhance the wet strength of the filter media; a colorant that may be required to impart a good appearance to the filter media; a fibrous retention aid; separation aids (e.g., silicone additives and associated catalysts); parent (S)An aqueous or hydrophobic agent; a wetting agent; an antistatic agent; or an antibacterial agent. If present, these additives may be added in an amount greater than 0 wt%, 0.01 wt%, 0.1 wt%, 1 wt%, 5 wt%, 10 wt%, and/or less than about 30 wt%, 25 wt%, 20 wt%, 15 wt%, 10 wt%, 9 wt%, 8 wt%, 7 wt%, 6 wt%, 5 wt%, 4 wt%, 3 wt%, 2 wt%, 1 wt%, or any combination thereof, including for example between 0.01 wt% and 1 wt%, based on the total weight of the filter medium.

The filter media may include pores through which fluid may pass during filtration. The pore size may be 0.5 μm to 10 μm, preferably 0.6 μm to 5 μm, or 0.7 to 4 μm. The average pore size of the pores may be 1 μm to 1.5 μm, preferably 1.1 μm to 1.4 μm.

Pore size may be measured in accordance with American Society for Testing and Materials (ASTM) standard 316-03 (2011) using capillary flow porosimetry techniques.

The filter media may exhibit a water column (in H) of at least 20 inches ₂ O), preferably at least 30in H ₂ Wet burst strength of O (wet burst strength). The wet burst strength of the filter media may be 20 to 150in H ₂ O. The dry MD tensile strength of the filter media may be at least 3lb/in, preferably at least 5lb/in. The dry MD tensile strength of the filter media can be 3lb/in to 30lb/in. The values are preferred for high flux fluid filtration performance.

Wet burst strength can be measured by applying increased pressure on a 2.5 inch wide test piece that has been saturated with water. Water columns are used to apply pressure. The water level was increased until the test piece ruptured. The water height was scaled using a scaling chart to measure water in inches of water column (in H ₂ O) represents wet burst strength.

Dry MD tensile strength may be measured according to Tappi T494 standard.

The present disclosure extends to a method of manufacturing the first component as defined herein. The method includes at least partially coating the core with nano-alumina. The coating may be performed before or during the formation of the filter medium.

The present disclosure further extends to a method of making the filter media defined herein. The method comprises the following steps:

(a) Forming a wet laid sheet from a fibrous slurry comprising a first component; and

(b) The wet laid sheet is dried to obtain a filter medium.

The fiber slurry may also include matrix fibers and/or binder fibers. The method may include at least partially coating the matrix fibers and/or the binder fibers with nano-alumina. The method may include simultaneously coating the core, matrix fibers, and/or binder fibers with nano-alumina. Alternatively, the method may comprise coating the core, matrix fibers and/or binder fibers sequentially with nano-alumina in any order.

The method may include at least partially coating the core with nano-alumina to form the first component. The first component may then be combined with matrix fibers, optional binder fibers, optional polymeric binder and/or optional additive components, and an aqueous medium to form a fiber slurry. The slurry may then be used to form a wet laid sheet.

The method may include forming a fiber slurry by combining the core, matrix fibers, and/or binder fibers in a solution (e.g., an aqueous solution) having nano-alumina, and simultaneously coating the core, matrix fibers, and/or binder fibers in the fiber slurry at least partially with nano-alumina. In this process, nano-alumina may be formed in situ by reacting aluminum metal (typically in powder or flake form) in an alkaline solution (such as aqueous NaOH, KOH or ammonium hydroxide) having a pH of 10 to 14, preferably 11 to 13, more preferably about pH 12. As the reaction proceeds, the nano-alumina formed by the reaction is deposited on the core, matrix fibers and/or binder fibers. After completion of the reaction, the reaction mixture may be purified by adding an acid (e.g., HCI, H ₂ SO ₄ 、HNO ₃ Etc.) to a pH of the solution between pH 6 and pH 7, preferably about pH 6.5. Once the pH is neutralized, the optional polymer bonding mentioned aboveOne or more of the agent and/or additive components may be combined with the fiber slurry. The combined mixture may then be formed into a wet laid sheet. The sheet may be oven dried to form the final filter media. The dried filter media can be corrugated, cut, folded, pleated, and assembled into a final filtration product for use.

The filter media is suitable for use in a method of filtering a fluid such as water. The method includes passing a fluid through a filter medium. The fluid may be forced through the filter media by application of externally applied pressure or by hydrostatic pressure. During filtration, impurities in the fluid bind to the filter medium (e.g., by electrostatic adhesion to the nano alumina coating) and/or become trapped by physical occlusion, thereby producing a purified fluid exiting the filter medium.

The filter media may be suitable for filtering fluids in industrial applications, such as removing contaminants from municipal drinking water or wastewater, treating industrial wastewater containing chemical or pharmaceutical contaminants, improving mine wastewater, or treating water contaminated by oil and gas drilling or processing operations.

The filter media may also be suitable for filtering fluids in household applications, such as purifying municipal tap water for drinking or cooking purposes.

Examples

Erythrosine test conditions

Erythrosine is a food grade pink dye and, like MS2 virus, is negatively charged at pH above 3.9. Quantification of erythrosine is relatively straightforward compared to MS2 virus. Erythrosine content can be quantified, for example, using a spectrophotometer. The entrapment of erythrosine by the filter medium can be a good indicator of the effectiveness of the filter medium for MS2 virus entrapment.

Handsheets comprising a core were prepared using the following components:

7.8% matrix fibers (regenerated fibrillated cellulose fibers-Lyocell 40);

15.3% matrix fibers (Trevira T256 synthetic bicomponent fibers);

33.5% core material;

43.5% nano alumina (after reaction).

The handsheets were cut into 25 mm samples, which were inserted into the sample holder and wetted with water. An aqueous erythrosin solution (10 mg/L) was prepared. Erythrosine solution was passed through the sample at a flow rate of 15 mm/min and the absorbance of each 20 ml filtrate was measured using a spectrophotometer. Results are plotted against eluent volume.

Example 1

Figure 1 shows the relative ability of four different filter media to filter erythrosine dye from water (using erythrosine test conditions). Each filter media includes a different glass type having a different alumina content. The alumina content of the four glass types is listed in table 1 below.

Table 1: four glass types of SiO used to make the filter media shown in FIG. 1 ₂ And Al ₂ O ₃ Content of

	A glass	B glass	C glass	E glass
					SiO2(％)	68.0 to 71.0	55.0 to 60.0	63.0 to 67.0	50.0 to 56.0
Al2O3(％)	2.5 to 4.0	4.0 to 7.0	3.0 to 5.0	13.0 to 16.0

Handsheets containing different glass types had the following composition:

7.8% matrix fibers (regenerated fibrillated cellulose fibers-Lyocell 40);

15.3% matrix fibers (Trevira T256 synthetic bicomponent fibers);

33.5% core material(A, B, C, E) glass, (glass fibers);

43.5% nano alumina (after reaction).

The pollutant removal performance was evaluated using the erythrosine test method.

For a given amount of filtered volume, a higher erythrosin reduction indicates higher performance. As shown in fig. 1, the amount of erythrosine filtered from the water by the E glass was greatest during the experiment until the volume of water filtered exceeded 140 a mL at which time the B glass filtered more erythrosine. The C glass and the a glass show much lower filtration capacities than the E glass and the B glass. Comparison of the alumina content of the four glasses shows that there is a correlation between the filtration performance and the alumina content. The E-glass with the highest alumina content filters the greatest amount of erythrosine.

Example 2

Figure 2 shows the relative ability of five different filter media to filter erythrosine dye from water (using the erythrosine test conditions described above). Although the comparison cannot be made directly due to the different amounts of core materials, the B glass sample can serve as a benchmark for evaluating the performance of five different filter media.

The alumina and silica contents of the five cores used to prepare the tested filter media are set forth in table 2 below.

Table 2: siO for five core materials for preparing the filter medium shown in FIG. 2 ₂ And Al ₂ O ₃ Content of

The ingredients used to prepare the handsheets had the ingredients shown in table 3 below:

table 3: the components of the handsheets tested (values given in wt.%)

Small changes were made to the ingredients to maintain the mechanical properties of the sheet. For example, the number of the cells to be processed,sheet ratio->Andthe sheet is tighter, so more ++is added>To increase the pore size. Will->Fiber addition toAnd PQ Corp->In the sheet to increase its rigidity.

The filter media was prepared as follows: will contain an alumina componentAnd Lyocell fibers (and, if applicable, (PET fibers)) are dispersed in water and mixed. When the mixture was homogeneous, aluminum powder was added with stirring and the pH of the mixture was adjusted to pH 12 by adding NaOH solution. The mixture was then heated to about 60 ℃ until the reaction was completed to form nano-alumina. The reaction was completed with the stop of bubbling of hydrogen. The mixture was then heated at 73 ℃ and then neutralized to pH 6.5 with sulfuric acid. After neutralization, additives such as Kymene GHP (wet flow additive) and Lubrizol (Hycar) 26450Latex (for general bonding) are added to the mixture to improve the properties of the nonwoven fabric.

Handsheets of filter media were prepared by a wet-laid process and dried. The physical properties of the handsheets are summarized in table 4 below.

Table 4: properties of the Filter Medium

Although having a lower amount of core material (10 wt% or 15 wt%), all samples, except the sample containing PQ Corp Advera401, had higher erythrosin degrading performance relative to the B glass sample. However, all five samples tested had erythrosine trapping capacity.

The invention may be further understood in conjunction with the following clauses.

1. A filter media comprising a first component having Al ₂ O ₃ A core in an amount of at least 10 wt%, preferably at least 20 wt%, and a nano alumina coating at least partially coating the core.

2. The filter media of any preceding clause, wherein the core is in the form of a fiber, a plate, a powder particle, a crystalline particle, an amorphous particle, or a porous particle (e.g., microporous or mesoporous Kong Keli).

3. The filter media of any preceding clause, wherein the Al of the core ₂ O ₃ The content is at least 10 wt%, preferably at least 20 wt%, 30 wt%, 40 wt%, 50 wt% or 60 wt%, and the core is in the form of a fiber.

4. The filter media of clause 3, wherein the core is an aluminoborosilicate glass fiber (such as E-glass) having less than 1% w/w alkali oxide.

5. The filter media of clause 3 or 4, the first component having Al ₂ O ₃ A glass fiber core in an amount of at least 10 wt%, preferably 10 to 20 wt%, or preferably 13 to 16 wt%, and a nano alumina coating at least partially coating the core, wherein the core is aluminoborosilicate glass fiber (E-glass) having less than 1% w/w alkali metal oxide, wherein the glass fiber core has an average diameter of 1 μm to 5 μm, wherein the filter medium further comprises matrix fibers, preferably one or more selected from cellulose fibers, synthetic fibers and fibrillated fibers, wherein the matrix fibers are at least partially coated with nano alumina, and wherein the filter medium comprises nano alumina in an amount of 30 to 60 wt% or 40 to 50 wt%, based on the total weight of the filter medium.

6. The filter media of clause 3, the first component having Al ₂ O ₃ A core in an amount of at least 10 wt% and a nano-alumina coating at least partially coating the core, wherein the core is selected from the group consisting of Al ₂ O ₃ Fibers (e.g., polycrystalline cotton), aluminum silicate fibers (e.g., ceramic fibers), and aluminum silicate glass fibers, wherein the average diameter of the fiber core is from 1 μm to 5 μm, wherein the filter medium further comprises matrix fibers, preferably one or more selected from the group consisting of cellulose fibers, synthetic fibers, and fibrillated fibers, wherein the matrix fibers are at least partially coated with nano-alumina, and wherein the filter medium comprises a porous fiberThe media comprises nano-alumina in an amount of 30 wt% to 60 wt% or 40 wt% to 50 wt%, based on the total weight of the filter media.

7. The filter media of clause 1 or 2, wherein the Al of the core ₂ O ₃ The content is at least 20 wt%, preferably at least 30 wt%, 40 wt%, 50 wt% or 60 wt%, and the core is in the form of a plate.

8. The filter media of clause 7, the first component having Al ₂ O ₃ A core in an amount of at least 20 wt%, preferably 50 to 100 wt%, and a nano-alumina coating at least partially coating the core, wherein the core is selected from aluminum silicate plates and Al ₂ O ₃ A panel wherein the average size of the core is from 1 to 30 μm, wherein the filter medium further comprises matrix fibers, preferably selected from one or more of cellulose fibers, synthetic fibers and fibrillated fibers, wherein the matrix fibers are at least partially coated with nano-alumina, and wherein the filter medium comprises nano-alumina in an amount of from 30 to 60 wt% or from 40 to 50 wt% based on the total weight of the filter medium.

9. The filter media of clause 1 or 2, wherein the Al of the core ₂ O ₃ The content is at least 20 wt%, preferably at least 30 wt%, 40 wt%, 50 wt% or 60 wt%, and the core is in the form of powder particles.

10. The filter media of clause 9, the first component having Al ₂ O ₃ A core in an amount of at least 20 wt%, preferably 50 wt% to 100 wt%, and a nano alumina coating at least partially coating the core, wherein the core is selected from aluminum silicate powder (such as zeolite), al ₂ O ₃ A powder and E-glass powder, wherein the average size of the core is from 1 to 30 μm, wherein the filter medium further comprises matrix fibers, preferably one or more selected from cellulose fibers, synthetic fibers and fibrillated fibers, wherein the matrix fibers are at least partially coated with nano-alumina, and wherein the filter medium comprises nano-alumina in an amount of from 30 to 60 wt% or from 40 to 50 wt%, based on the total weight of the filter medium.

11. The filter media of any preceding clause, wherein the first component comprises 10 to 99 weight percent, preferably 50 to 95 weight percent, or more preferably 70 to 90 weight percent of the nano-alumina coating.

12. The filter media of any preceding clause, wherein the core comprises 1 to 90 weight percent, preferably 5 to 50 weight percent, more preferably 10 to 30 weight percent of the first component.

13. The filter media of any one of clauses 5, 6, 8, or 10, wherein the matrix fibers comprise cellulosic fibers.

14. The filter media of any one of clauses 5, 6, 8, or 10, wherein the matrix fibers comprise synthetic fibers.

15. The filter media of any one of clauses 5, 6, 8, or 10, wherein the matrix fibers comprise fibrillated fibers.

16. The filter medium of clause 15, wherein the fibrillated fibers comprise fibrillated cellulose fibers and preferably regenerated cellulose fibers.

17. The filter media of any preceding clause, wherein the core has at least 80 wt% Al ₂ O ₃ SiO content of less than 20% by weight ₂ Content, wherein the core is in the form of powder or fiber, and wherein the average particle diameter of the core is 1 μm to 30 μm when the core is a powder particle, and the average diameter of the core is 1 μm to 5 μm when the core is a fiber.

18. The filter media of any preceding clause, wherein the core comprises at least 1 weight percent, preferably at least 5 weight percent, more preferably 5 to 70 weight percent, even more preferably 5 to 50 weight percent of the total weight of the filter media.

19. The filter medium according to any of the preceding clauses, wherein the filter medium comprises 5 to 70 wt.%, preferably 20 to 50 wt.% of matrix fibers based on the total weight of the filter medium.

20. The filter medium according to any of the preceding clauses, wherein the filter medium comprises 5 to 70 wt.%, preferably 5 to 50 wt.% of cellulose fibers based on the total weight of the filter medium.

21. A method of manufacturing a first component for a filter medium as defined in any one of clauses 1 to 20, the method comprising at least partially coating a core with nano-alumina.

22. A method of manufacturing a filter medium as defined in any one of clauses 1 to 20, the method comprising:

(b) The wet laid sheet is dried to obtain a filter medium.

23. The method of clause 22, further comprising coating the core with nano-alumina to form the first component.

24. The method of clause 23, wherein the fiber slurry further comprises matrix fibers and/or binder fibers, and wherein the method comprises simultaneously at least partially coating the core, matrix fibers, and/or binder fibers with nano-alumina.

25. A method of filtering a fluid, the method comprising passing the fluid through the filter medium of any one of clauses 1-20.

Claims

1. A filter media comprising a first component having Al ₂ O ₃ A core in an amount of at least 10 wt% and a nano alumina coating at least partially coating the core, wherein the core is in the form of fibers, plates or powder particles, and wherein the filter medium further comprises matrix fibers as a second component.

2. The filter media of any preceding claim, wherein the Al of the core ₂ O ₃ The content is at least 20 wt%, preferably at least 40 wt%, preferably at least 60 wt%, or preferably at least 80 wt%.

3. A filter medium according to any preceding claim, wherein the core is of SiO ₂ The content is less than 60 weight percentThe amount is preferably less than 40 wt%, or preferably less than 20 wt%.

4. A filter medium according to any preceding claim, wherein the core is selected from one or more of alumina powder, alumina fibres, crystalline aluminosilicate and amorphous aluminosilicate.

5. A filter medium according to any preceding claim, wherein the average size of the core is from 0.1 μm to 50 μm.

6. The filter media of any preceding claim, wherein the first component comprises 10 to 99 wt%, preferably 50 to 95 wt%, or preferably 70 to 90 wt% nano alumina coating.

7. A filter medium according to any preceding claim, wherein the core comprises from 1 to 90 wt%, preferably from 5 to 50 wt%, more preferably from 10 to 30 wt% of the first component.

8. A filter medium according to any preceding claim, wherein the matrix fibres are selected from one or more of cellulose fibres, synthetic fibres and fibrillated fibres.

9. A filter medium according to any preceding claim, wherein the matrix fibres are at least partially coated with nano alumina.

10. The filter medium according to any one of the preceding claims, comprising nano-alumina in an amount of 20 to 70 wt%, preferably 30 to 60 wt%, preferably 40 to 50 wt%, based on the total weight of the filter medium.

11. A filter medium according to any of the preceding claims, wherein the filter medium comprises less than 1 wt%, preferably less than 0.1 wt% glass fibres.

12. The filter media of any preceding claim, wherein the mass ratio of the first component to the second component of the filter media is from 4:1 to 1:10.

13. A filter medium according to any one of the preceding claims, wherein the filter medium is a nonwoven fabric.

14. A filter medium according to any of the preceding claims, wherein the filter medium has a wet burst strength of at least 20 inches of water, preferably at least 30 inches of water.

15. A filter medium according to any of the preceding claims, wherein the filter medium has a tensile strength of at least 3lb/in, preferably at least 5lb/in.

16. A filter medium according to any of the preceding claims, wherein the core comprises at least 1 wt%, preferably at least 5 wt%, more preferably 5 wt% to 70 wt%, even more preferably 5 wt% to 50 wt% of the total weight of the filter medium.

17. A filter medium according to any of the preceding claims, wherein the filter medium comprises 5 to 70 wt%, preferably 20 to 50 wt% of matrix fibers based on the total weight of the filter medium.

18. A filter medium according to any of the preceding claims, wherein the filter medium comprises 5 to 70 wt%, preferably 5 to 50 wt% cellulose fibers based on the total weight of the filter medium.

19. A method of manufacturing a first component for a filter medium as defined in any one of claims 1 to 18, the method comprising at least partially coating a core with nano-alumina.

20. A method of manufacturing a filter medium as defined in any one of claims 1 to 18, the method comprising:

(a) Forming a wet laid sheet from a fibrous slurry comprising the first component and the second component; and

(b) Drying the wet laid sheet to obtain the filter medium.

21. A method of filtering a fluid, the method comprising passing the fluid through the filter medium of any one of claims 1 to 18.