Method for oxidizing manganese species in a treatment device

Abstract

This invention relates to a method for oxidizing manganese in a processing apparatus, the method comprising the following steps: (A) A manganese substance having a first oxidation state is provided in the processing apparatus. (B) The processing apparatus provides one or more anodes and at least one cathode. (C) Applying an electric current to the anode and the cathode, such that at least a portion of the manganese substance having a first oxidation number is anoly oxidized to a manganese substance having a second oxidation number higher than the first oxidation number. The characteristic is that, based on the total volume of the at least one anode, at least one of the one or more anodes has a volume of 6 m³. Surface density of 2 / L or greater.

Description

Technical Field

[0001] This invention relates to a method for oxidizing manganese in a processing apparatus, the method comprising the following steps: (A) A manganese substance having a first oxidation state is provided in the processing apparatus. (B) The processing apparatus provides one or more anodes and at least one cathode. (C) Applying an electric current to the anode and the cathode such that at least a portion of the manganese substance having a first oxidation number is anoly oxidized to a manganese substance having a second oxidation number higher than the first oxidation number. The feature is that, based on the total volume of the at least one anode, at least one of the one or more anodes has a surface density of 6 m² / L or greater. Prior Technology

[0002] Metallized non-metallic substrates (such as plastic substrates) have a long history in modern technology. Typical applications include the automotive industry and hygiene products.

[0003] However, accommodating metallic layers on non-metallic / non-conductive substrates is demanding. Typically, various methods begin with surface finishing of the substrate surface, commonly referred to as etching. A delicate balance is usually required to ensure sufficient surface roughening without introducing significant defects.

[0004] Many methods and etching compositions are known, including those containing environmentally problematic chromium materials, such as hexavalent chromium materials (e.g., chromic acid). While these compositions typically provide very strong and acceptable etching results, there is a growing need for environmentally friendly alternatives, which have been provided to some extent in this technology. In many cases, manganese-based etching compositions are instead utilized.

[0005] Typically, manganese-based etching compositions are acidic or alkaline. However, acidic manganese-based etching compositions are inherently more prone to degradation, specifically permanganate-based etching compositions. Therefore, these etching compositions require a constant and relatively high level of replenishment of active manganese. Preferably, these etching compositions are continuously circulated to maintain a relatively constant level of active manganese. This is typically achieved by chemical oxidation or by applying an electric current. Various regeneration methods and apparatus are known in this art.

[0006] CN 109628948 A refers to a regeneration device comprising a ceramic diaphragm for recycling permanganate ion solution.

[0007] CN 1498291 A refers to an electrolytic regeneration apparatus for regenerating etching solutions.

[0008] WO 2013 / 030098 A1 refers to an apparatus for at least partially regenerating a treatment solution containing permanganate for treating and / or etching plastic parts.

[0009] WO 01 / 90442 A1 refers to a cathode for an electrochemical arrangement for regenerating permanganate etching solution and an apparatus for electrolytically regenerating permanganate etching solution.

[0010] Regeneration efficiency typically depends on the current fed into each individual processing unit and the way that current interacts with each individual manganese substance.

[0011] There is a continued need to further improve the efficiency of individual regeneration methods and devices.

[0012] Purpose of the invention Therefore, the object of the present invention is to provide a method for efficiently oxidizing manganese materials in a processing apparatus, thereby allowing for a compact design of individual processing apparatuses. Preferably, the object is to provide a method specifically suitable for processing (i.e., recycling) acidic manganese-based etching compositions (specifically, containing permanganates) with improved efficiency. Summary of the Invention

[0013] The aforementioned objective is achieved by a method for treating manganese oxide in a processing device, the method comprising the following steps: (A) A manganese substance having a first oxidation state is provided in the processing apparatus. (B) The processing apparatus provides one or more anodes and at least one cathode. (C) Applying an electric current to the anode and the cathode such that at least a portion of the manganese substance having a first oxidation number is anoly oxidized to a manganese substance having a second oxidation number higher than the first oxidation number. The feature is that, based on the total volume of the at least one anode, at least one of the one or more anodes has a surface density of 6 m² / L or greater.

[0014] The method of this invention allows for highly efficient oxidation (preferably regeneration) of manganese because, based on the total volume of the at least one anode, it specifically utilizes at least one anode having a surface density of 6 m² / L or greater. In other words, this anode provides a very large effective surface area in at least one single anode. Furthermore, each liter of this large effective surface area provides a correspondingly large area for contact with manganese having a first oxidation state. Therefore, the manganese is efficiently oxidized at the anode to provide manganese having the second oxidation state.

[0015] However, conventional methods typically utilize known anodes with generally low surface density, most commonly below 6 m² / L. This is also evident in the relatively low surface coefficient of these conventional anodes; parameters commonly used for electrodes with predominantly two-dimensional designs (such as plates, meshes, etc.). For example, expanded metal lattice anodes (metal meshes; Streckmetall) offer surface coefficients between 2 and 2.5 at most, which are considered high. However, novel manufacturing techniques (such as 3D printing) allow for the production of anodes with significantly higher surface areas per volume compared to conventional anode designs. Furthermore, they can be designed into various geometries, specifically in all three dimensions. All of this allows for a reduction in the size of individual processing devices and an increase in their efficiency. Moreover, if for some reason this stacking is not required, it prevents the stacking of conventional anodes into layers to simulate anodes with high surface areas per volume. Instead, specific geometries can be intentionally formed to meet even more complex requirements, and the use of these anodes becomes more flexible.

[0016] In some cases, the method of the present invention is preferred, wherein one or more anodes are single anodes and simultaneously at least one anode having a surface density of 6 m² / L or greater. However, in other cases, the method of the present invention is preferred, wherein more than one anode is provided in step (B), wherein at least one of them has a surface density of 6 m² / L or greater, preferably all of them have a surface density of 6 m² / L or greater. Implementation

[0017] As mentioned above, the method of the present invention anodizes a manganese substance having a first oxidation number into a manganese substance having a second oxidation number, wherein the second oxidation number is higher than the first oxidation number.

[0018] The method of the present invention is preferred, wherein the first oxidation number is +4 or lower.

[0019] The method of the present invention is preferred, wherein the first oxidation number includes +4, +3 and / or +2.

[0020] The method of the present invention is preferred, wherein the manganese substance having a first oxidation number comprises Mn2+ ions and / or Mn3+ ions.

[0021] The method of the present invention is preferred, wherein the manganese substance having a first oxidation state comprises manganese particles (preferably its oxide), colloidal manganese particles (preferably its oxide), and preferably colloidal MnO2 particles. This preference includes, optionally, its polymers.

[0022] The method of the present invention is preferred, wherein the second oxidation number is higher than +4, preferably +7 (preferably including +7). However, this does not necessarily exclude manganese substances having an oxidation number of +5 or +6.

[0023] Ideally, manganese substances with a second oxidation number contain permanganate ions.

[0024] The method of the present invention preferably includes a manganese substance having a first oxidation state in a liquid, preferably in an acidic liquid. In fact, the method of the present invention is most effective when dealing with such an acidic liquid. Preferably, the liquid system is used in a processing composition for treating (preferably etching) a non-metallic substrate (preferably a plastic substrate) in an etching chamber. Preferably, the liquid system is in contact with the plastic substrate before step (A). In other words, preferably, the manganese substance having a first oxidation state is brought into contact with the non-metallic substrate (preferably a plastic substrate) before step (A).

[0025] The method of the present invention is preferred, wherein the liquid contains an acid, preferably an inorganic acid, and most preferably phosphoric acid.

[0026] The method of the present invention preferably involves returning manganese material having a second oxidation state to the etching chamber. Preferably, the manganese material having the second oxidation state is reused to process (preferably etch) a non-metallic substrate (preferably a plastic substrate). Therefore, the method of the present invention is preferably a method for recycling manganese material. In this document, "recycling" refers to the re-oxidation of (preferably used) manganese material and its subsequent reuse. The method of the present invention is preferably carried out continuously or at least semi-continuously. Continuous preferably means that at least steps (A) and (C) of the method of the present invention are carried out continuously (i.e., without interruption). Conversely, semi-continuous preferably means that steps (A) and / or step (C) are interrupted from time to time for at least a short period of time. This interruption may be necessary to maintain or stabilize the concentration of a substance present during the method of the present invention. However, continuous use is preferred.

[0027] Typically, permanganate etching is used to chemically reduce the permanganate to manganese with a lower oxidation number, and the plastic material is at least partially oxidized.

[0028] In some cases, the method of the present invention is preferred, wherein the processing apparatus used in the method of the present invention is external to the etching chamber. This means that the processing apparatus is outside the etching chamber. This is generally preferred. However, in other cases, the method of the present invention is preferred, wherein the processing apparatus used in the method of the present invention is at least partially integrated into the etching chamber. This prefers that the processing apparatus is internal to the etching chamber.

[0029] The method of the present invention is preferred, wherein the non-metallic substrate (preferably a plastic substrate) comprises acrylonitrile butadiene styrene (ABS), acrylonitrile butadiene styrene-polycarbonate (ABS-PC), polypropylene (PP), polyamide (PA), polyurethane (PU), polyepoxide (PE), polyacrylate, polyetherimide (PEI), polyetherketone (PEK), mixtures thereof, and / or composites thereof; preferably acrylonitrile butadiene styrene (ABS), acrylonitrile butadiene styrene-polycarbonate (ABS-PC), polyamide (PA), polyurethane (PU), polyepoxide (PE), polyacrylate, mixtures thereof, and / or composites thereof. These plastic substrates are commonly used in decorative applications, such as automotive parts, specifically ABS and ABS-PC.

[0030] To maintain the high efficiency and energy optimization of the method of the present invention, one or more anodes and at least one cathode preferably have a relatively small distance between them. The method of the present invention preferably has the one or more anodes and at least one cathode having a distance between them ranging from 1 mm to 100 mm, preferably 2 mm to 90 mm, more preferably 3 mm to 80 mm, even more preferably 4 mm to 70 mm, and most preferably 5 mm to 60 mm. Generally, the shorter the distance, the lower the voltage, and therefore the more energy is consumed. Therefore, in some cases, the method of the present invention is preferably wherein the one or more anodes and at least one cathode have a distance between them ranging from 9 mm to 70 mm, preferably 10 mm to 60 mm, more preferably 11 mm to 50 mm, even more preferably 12 mm to 30 mm, and most preferably 13 mm to 20 mm. This is preferably suitable for at least one anode having a surface density of 6 m² / L or greater.

[0031] The method of the present invention is generally preferred, wherein distance is defined as the shortest distance between one or more anodes and the nearest (preferably corresponding) at least one cathode. In other words, the distance is preferably the shortest external distance between the one or more anodes and the nearest (preferably corresponding) at least one cathode. The term "external" preferably means that the outermost edge of the one or more anodes directly faces the outermost edge of the nearest at least one cathode.

[0032] The method of the present invention is preferred in that at least one cathode system is constructed (at least primarily) around (in the sense of enclosure) one or more anodes, specifically around at least one anode having a surface density of 6 m² / L or greater. In other words, the at least one cathode at least primarily surrounds or circulates around or around the one or more anodes, preferably at least one anode having a surface density of 6 m² / L or greater, wherein this wording does not limit the overall arrangement to circular. However, this anode / cathode arrangement is not necessarily mandatory within the context of the present invention.

[0033] In some cases, the method of the present invention is preferred in which one or more anodes and at least one cathode are separated from each other by a permeable barrier (preferably a permeable membrane). In this embodiment, an anolyte and a catholyte are preferably formed. Preferably, the anolyte contains a manganese substance having a first oxidation state. Therefore, preferably, the anolyte is the liquid described above. The catholyte preferably contains an inorganic acid, more preferably sulfuric acid and / or phosphoric acid, most preferably only phosphoric acid.

[0034] Despite the presence of a permeable barrier, the current applied in step (C) is flowable such that at least a portion of the manganese material having the first oxidation number is anoly oxidized to the manganese material having the second oxidation number.

[0035] Preferably, if this permeable barrier is used, substantially all manganese material is separated from at least one cathode. This "preferably" means that the permeable barrier is essentially impermeable to negatively charged or neutral manganese material.

[0036] The method of the present invention is preferred, wherein the permeable barrier is an ion-selective permeable barrier, preferably an ion-selective permeable membrane.

[0037] The method of the present invention is preferred, wherein the permeable barrier is a cation-selective permeable barrier, and more preferably a cation-selective permeable membrane. Therefore, it is best to allow only cations to permeate.

[0038] In some cases, the method of the present invention is preferred, wherein the permeable barrier is not a mineral. Conversely, in other cases, the permeable barrier is preferably a mineral, preferably comprising ceramic. However, in some other cases, the method of the present invention is preferred, wherein the permeable barrier is substantially free of (preferably not containing) ceramic.

[0039] The method of the present invention is preferred in that the permeable barrier is organic. The method of the present invention is further preferred in that the permeable barrier is organic and contains fluorine (preferably fluorinated), most preferably organic and perfluorinated. Preferably, at least one permeable barrier is a Nafion-type membrane, however, the membrane is not particularly limited to this specific brand. The membrane (preferably such organic membrane) is very thin and therefore positively contributes to relatively short distances, and thus contributes to compact designs. Conversely, the method of the present invention is also preferred in that one or more anodes and at least one cathode are not separated from each other by a permeable membrane (preferably a permeable barrier).

[0040] In this invention, it is essential that at least one anode has a surface density of 6 m² / L or greater. The method of this invention preferably has a surface density of 8 m² / L or greater, more preferably 10 m² / L or greater, more preferably 14 m² / L or greater, even more preferably 16 m² / L or greater, and most preferably 20 m² / L or greater. Generally, the higher the surface density, the more efficient the method can potentially be, provided that sufficient mass transfer is guaranteed through the at least one anode. With newly discovered techniques, the generation of anodes with this surface density has become increasingly efficient. Surprisingly, it has been found that excellent mass transfer and efficiency can be achieved simultaneously. This is surprising because, until now, it has been assumed that anodes with a large effective surface area in a relatively small volume are affected by harmful shielding effects, meaning that the electric field has only a very small penetration depth. Surprisingly, in this invention, despite the compact design, the at least one anode provides a sufficiently high current efficiency / turnover rate. Although a shielding effect does occur, it is surprisingly low and tolerable, resulting in a significant benefit from a relatively large total effective anode surface area. Surprisingly, this is despite the fact that at least one anode provides a Faraday cage-like barrier. In other words, the anode unexpectedly allows for an extremely compact and dense anode structure while remaining highly efficient despite the shielding effect.

[0041] In the context of this invention, surface density is a parameter that defines the total effective surface area per geometric volume.

[0042] For example, a plate with a geometry of 1 m² and a thickness of 1 mm typically has a total effective surface area of ​​2.004 m², including the areas of the front, back, and cut edges. The geometric volume of this plate is 1 m x 1 m x 10⁻³ m = 10⁻³ m³ = 1 liter. Therefore, the surface density of this plate is 2.004 m² / L, or approximately 2 m² / L. This is also consistent with a general parameter called the "surface coefficient" (total effective surface area per geometric area), which in this case, for this primary two-dimensional plate, is approximately 2.

[0043] Typically, if, for example, a plate has holes and a mesh has openings, a surface density higher than 2 is obtained by defining the number and size, respectively. This also applies to the surface coefficient. However, the surface coefficient of currently commercially available meshes typically does not exceed 2.5. Furthermore, this surface coefficient is insufficient to define an electrode with a significant third dimension. In contrast to dimensionless surface coefficients, the surface density within the text of this invention is defined as m² per liter for each individual anode.

[0044] The method of the present invention is preferred in that at least one anode having a surface density of 6 m² / L or greater comprises (preferably within the anode) a random structural pattern, a uniform structural pattern, or a regularly repeating structural pattern. A uniform structural pattern and / or a regularly repeating structural pattern are preferred, especially in 3D-printed anodes, fabric anodes, permanently fixed stacked monolayer anodes (preferably permanently fixed by welding, gluing, and / or riveting), separable stacked monolayer anodes (preferably separable by loosening and / or unscrewing), and filled bed anodes with prescribed packaging. In the context of this invention, random (i.e., chaotic and without long-range order) structural patterns are somewhat undesirable but typical, for example, for so-called filled bed anodes, knotted anodes, foam anodes, and 3D-printed anodes with random structural patterns, such as those with loose filler material. Generally, uniform and regularly repeating structural patterns ensure a uniform penetration depth of the electric field into the interior of the anode, which is considered an advantage over random structural patterns. Preferably, the structural pattern includes cavities and / or holes within the anode, which can be substantially approached from the outer surface and preferably result in a relatively large total effective surface area. On the other hand, random structural patterns are readily available, and packed bed anodes are relatively inexpensive.

[0045] Generally, a preferred single-layer anode includes a grid and / or plate, and a preferred expanded metal (i.e., an expanded grid).

[0046] The method of this invention is preferred, wherein at least one anode having a surface density of 6 m² / L or greater comprises (preferably) a single-segment anode or a separable multi-segment anode. In the context of this invention, a single-segment anode refers to an anode consisting of a single piece and which can only be separated / disassembled by destructive forces. In other words, such an anode is not designed for disassembly. Preferred single-segment anodes include 3D-printed anodes, fabric anodes, permanently fixed stacked single-layer anodes (preferably permanently fixed by welding, gluing, and / or riveting), bonded anodes, packed bed anodes having sintered, welded, and / or compressed anode materials, and / or foam anodes.

[0047] Conversely, the separable multi-segment anode comprises at least two (preferably more) individual connecting segments designed for non-destructive disassembly. A preferred separable multi-segment anode includes a separable stacked monolayer anode (preferably separable by unscrewing and / or loosening), a packed bed anode with pre-defined packaging, and / or a packed bed anode with loose packing material.

[0048] The method of the present invention is generally preferred, wherein the surface density is in the range of 6 m² / L to 100 m² / L, more preferably 8 m² / L to 70 m² / L, more preferably 10 m² / L to 50 m² / L, even more preferably 12 m² / L to 40 m² / L, and even more preferably 14 m² / L to 30 m² / L, most preferably 16 m² / L to 22 m² / L.

[0049] These specific surface densities are best obtained using the following anodes: The method of the present invention preferably includes an anode system having a surface density of 6 m² / L or greater selected from the group consisting of 3D printed anodes, fabric anodes, foam anodes, stacked monolayer anodes, and packed bed anodes. More preferably, the preferred anode system is as defined above.

[0050] In some cases, the method of the present invention is preferred, wherein step (B) includes: - Manufacture one or more anodes (preferably at least one anode having a surface density of 6 m² / L or greater), preferably 3D printed anodes, fabric anodes, foam anodes and filled bed anodes, most preferably 3D printed anodes and fabric anodes.

[0051] However, within the text of this invention, it is irrelevant whether the method of this invention includes manufacturing individual anodes or whether it simply provides anodes but manufactures them in different locations and subsequently repositions them for use in the method of this invention.

[0052] The method of the present invention is preferred, wherein the fabric anode comprises braided metal wires and / or braided metal filaments. Typically, the thickness of these wires and filaments defines the maximum surface density. For example, for wires and filaments having a thickness of 0.2 mm, the maximum surface density, based on the total volume of the anode, is preferably in the range of 18 m² / L to 22 m² / L, preferably about 20 m² / L. For wires and filaments having a thickness of 0.1 mm, the maximum surface density, based on the total volume of the anode, is preferably in the range of 30 m² / L to 42 m² / L, preferably 35 m² / L to 40 m² / L.

[0053] The method of the present invention is preferred, wherein the fabric anode includes a plain weave anode and / or a plush fabric anode.

[0054] The method of the present invention is preferred, wherein the 3D printing anode comprises a 3D printing lattice anode and / or a 3D printing sheet anode. Typically, the printing resolution in 3D printing defines the maximum surface density. For example, based on the total volume of the anode, a 3D printing dot having a minimum size of approximately 50 µm preferably results in a 3D printing anode having a surface density in the range of at least 60 m² / L to up to 100 m² / L, preferably 70 m² / L to 90 m² / L.

[0055] The method of the present invention is preferred, wherein the foam anode comprises a solid and / or flexible foam anode.

[0056] The method of the present invention is preferred, wherein the packed bed anode comprises a packing compartment selected from the group consisting of: Raschig rings, Lessintao rings, Pall rings, Bearetzky rings, Dixon rings, mesh balls, and Hex-X compartments.

[0057] In the method of the present invention, preferably at least one anode having a surface density of 6 m² / L or greater comprises a 3D printed anode and / or a fabric anode.

[0058] 3D-printed anodes (e.g., as mentioned above) can theoretically be manufactured with potentially very high surface densities. Preferably, for such anodes, the surface density is 100 m² / L or less based on the total volume of the anode, more preferably in the range of 30 m² / L to 80 m² / L, and more preferably in the range of 40 m² / L to 50 m² / L.

[0059] Ideally, based on the total volume of the anode, the fabric anode has a surface density in the range of 10 m² / L to 40 m² / L, more preferably 15 m² / L to 30 m² / L.

[0060] In some cases, the method of the present invention is preferred in that one or more anodes does not contain stacked monolayer anode layers having an individual surface density of 3 m² / L or lower (preferably as defined above). Most preferably, the one or more anodes does not contain stacked monolayer anodes having an individual surface coefficient of 3 or lower. In some cases, the method of the present invention is even more preferred in that the one or more anodes (preferably at least one anode having a surface density of 6 m² / L or greater) do not contain stacked monolayer anodes at all. Although stacked monolayer anodes are substantially possible and desirable for use within the text of this invention, they typically require assembly compared to other preferred anodes manufactured in substantially automated manufacturing methods.

[0061] The method of the present invention is preferred, wherein at least one anode having a surface density of 6 m² / L or greater comprises a material selected from the group consisting of: platinum, titanium, niobium, lead, gold, alloys comprising at least one thereof, oxides thereof, and mixtures thereof.

[0062] The method of the present invention is preferred in that one or more anodes comprises a material selected from the group consisting of: platinum, titanium, niobium, lead, gold, alloys comprising at least one of the following, oxides thereof, and mixtures thereof. This preference means that it is applicable to all anodes.

[0063] As previously stated, manganese substances having a first oxidation state are preferably provided / contained in the liquid. Since the liquid is preferably highly acidic and due to the strong oxidizing properties of certain manganese substances, it is preferable to carefully select one or more anode materials. A preferred minimum requirement is that each material is (electro)chemically inert to the liquid. Typically, the aforementioned materials exhibit resistance, at least for a period of time. The method of the present invention preferably includes one or more anodes comprising platinum-plated anodes and / or platinum-plated anodes, preferably platinum-plated titanium anodes, and / or platinum-plated niobium anodes. This anode material maintains high resistance even over a longer period. This is preferably applicable to at least one anode having a surface density of 6 m² / L or greater.

[0064] In some cases, the method of the present invention is preferred, wherein the material comprises lead and / or lead alloys. Preferred lead alloys contain tin and / or silver as alloying elements. However, in most cases, our experiments have shown that excellent efficiency is obtained if the material contains platinum, preferably platinum-plated material. Furthermore, lead is increasingly becoming an undesirable material in terms of human and environmental hazards.

[0065] As mentioned above, in step (B), at least one cathode is provided.

[0066] The method of the present invention is generally preferred in that at least one cathode comprises a material selected from the group consisting of: titanium, platinum, niobium, lead, alloys comprising at least one of the following, their oxides, stainless steel, and mixtures thereof. The method of the present invention is generally preferred in that the at least one cathode is preferably made of a wide range of materials, provided that each material is sufficiently acid-resistant, sufficiently stable against hydrogen embrittlement, and / or chemically resistant to liquids (if in contact with the liquid). In some cases, the method of the present invention is preferred in that the material of the at least one cathode is the same as the material of at least one anode having a surface density of 6 m² / L or greater, preferably the same as the material of one or more anodes. However, in other cases, preferably, the material of the at least one cathode is different from the material of at least one anode having a surface density of 6 m² / L or greater, preferably the material of one or more anodes.

[0067] Our experiments have shown that in some cases, cathode current protection of at least one cathode allows the use of even less resistant materials, preferably stainless steel. This is most suitable if the method of the present invention utilizes a permeable barrier, preferably a permeable membrane, to form a cathode electrolyte, preferably a cathode electrolyte containing phosphoric acid, more preferably containing only mineral acid phosphoric acid, and most preferably containing only acidic phosphoric acid.

[0068] In some cases, the method of the present invention is preferred, wherein at least one cathode comprises a sheet cathode, a mesh cathode, a woven mesh cathode, an expanded metal cathode, a 3D printed cathode, a fabric cathode, a foam cathode, and / or a packed bed cathode. A sheet cathode and / or a mesh cathode are preferred.

[0069] The method of the present invention preferably includes one or more anodes providing a total effective anode surface area A1 and at least one cathode providing a total effective cathode surface area A2, wherein A1 is greater than A2. Preferably, this is applicable to at least one anode having a surface density of 6 m² / L or greater.

[0070] In the context of this invention, "total effective surface area" refers to the area available for participation in electrochemical redox reactions. This is also used in / included in the definition of surface density.

[0071] In some cases, the method of the present invention is preferred, wherein 50% or more of A1 comes from at least one anode having a surface density of 6 m2 / L or more, preferably 60% or more, more preferably 70% or more, even more preferably 80% or more, and even more preferably 90% or more, most preferably 95% or more, and even most preferably 99% or more.

[0072] The method of the present invention is generally preferred, wherein A1:A2 is in the range of 5:1 to 100:1, more preferably 10:1 to 85:1, even more preferably 15:1 to 70:1, even more preferably 20:1 to 60:1, and most preferably 30:1 to 50:1.

[0073] In some cases, the method of the present invention is preferred, wherein A1:A2 is in the range of 5:1 to 30:1, more preferably 6:1 to 25:1, and even more preferably 7:1 to 20:1.

[0074] However, in other cases, the method of the present invention is preferred, wherein A1:A2 is at least 10:1, more preferably at least 20:1, even more preferably at least 30:1, and most preferably at least 40:1. The method of the present invention is even more preferred, wherein A1:A2 is in the range of 10:1 to 100:1, more preferably 20:1 to 70:1, even more preferably 30:1 to 50:1, and most preferably 35:1 to 45:1. In some cases, this is preferred if a permeable barrier is not utilized.

[0075] The method of the present invention is generally preferred, wherein, based on the total free internal volume in the processing device, A1 is in the range of 10 dm² / dm³ to 200 dm² / dm³, more preferably 15 dm² / dm³ to 175 dm² / dm³, more preferably 20 dm² / dm³ to 150 dm² / dm³, even more preferably 25 dm² / dm³ to 125 dm² / dm³, even more preferably 30 dm² / dm³ to 100 dm² / dm³, most preferably 35 dm² / dm³ to 75 dm² / dm³, even more preferably 40 dm² / dm³ to 50 dm² / dm³.

[0076] In the context of this invention, the total free internal volume corresponds to the total internal volume of the processing apparatus minus the volume of at least one or more anodes (i.e., tare volume), including, for example, the parts used for mounting thereon, and preferably all other installations within the processing apparatus, such as pipes. In other words, the total free internal volume is more preferably the volume in the processing apparatus that the liquid can occupy at its maximum capacity.

[0077] In the context of this invention, the aforementioned parameter represents the anode density (i.e., the total effective anode surface area per dm³ of the total free internal volume). In the method of this invention, it is desirable to achieve a relatively high anode density to oxidize manganese materials having a first oxidation state very efficiently, i.e., to oxidize as much and as quickly as possible under given conditions. In practice, the aforementioned anode density is generally considered to be high. It is a parameter characterizing the compact and dense packaging of the processing apparatus.

[0078] The method of the present invention is preferred, wherein the processing device has at least one inner surface comprising, or composed of, fluorinated plastic, preferably polyvinylidene fluoride (PVDF) and / or polytetrafluoroethylene (PTFE). Our experiments have shown that these materials possess the required chemical resistance to prevent damage and harm to the processing device (e.g., by means of dissolution and / or etching).

[0079] In step (C) of the method of the present invention, a current, preferably an electrical current, is applied.

[0080] The method of the present invention is preferred, wherein in step (C), the current has a current density in the range of 0.1 A / dm² to 10 A / dm², preferably 0.2 A / dm² to 8 A / dm², more preferably 0.3 A / dm² to 6 A / dm², even more preferably 0.4 A / dm² to 4 A / dm², even more preferably 0.5 A / dm² to 2.8 A / dm², and most preferably 0.6 A / dm² to 1.5 A / dm². This is the anode current density, preferably based on the effective anode surface area. Preferably, the anode current density is relatively low to reduce the generation of unwanted anode oxygen, which further reduces current efficiency.

[0081] The method of the present invention is preferred, wherein in step (C), at least one cathode has a cathode current density in the range of 2 A / dm² to 70 A / dm², preferably 3 A / dm² to 60 A / dm², more preferably 4 A / dm² to 50 A / dm², even more preferably 5 A / dm² to 40 A / dm², even more preferably 6 A / dm² to 30 A / dm², and most preferably 7 A / dm² to 20 A / dm². This is the cathode current density. In contrast to the relatively low anode current density, it needs to have a relatively high cathode current density. This typically leads to hydrogen production. Although this is generally undesirable, within the context of the present invention, it can suppress undesirable cathode decomposition reactions of the desired manganese material.

[0082] In some cases, the method of the present invention is preferred, wherein in step (C), at least one cathode has a cathode current density in the range of 2 A / dm² to 30 A / dm², more preferably 3 A / dm² to 25 A / dm², more preferably 4 A / dm² to 20 A / dm², even more preferably 5 A / dm² to 15 A / dm², and most preferably 6 A / dm² to 12 A / dm².

[0083] In other cases, the method of the present invention is preferred, wherein in step (C), at least one cathode has a cathode current density in the range of 10 A / dm² to 70 A / dm², more preferably 12 A / dm² to 65 A / dm², more preferably 14 A / dm² to 60 A / dm², even more preferably 16 A / dm² to 50 A / dm², and most preferably 18 A / dm² to 35 A / dm².

[0084] As mentioned above, the method of the present invention is preferred, wherein the manganese substance having a first oxidation number is contained in a liquid.

[0085] The method of the present invention is preferred, wherein in step (A), based on the total volume of the liquid, all manganese substances in the liquid (i.e., including manganese substances having a first oxidation state) have a total concentration in the range of 0.02 mol / L to 0.3 mol / L, preferably 0.03 mol / L to 0.25 mol / L, and most preferably 0.035 mol / L to 0.2 mol / L. This is preferably applicable to the liquid in step (A) and after step (C).

[0086] The method of the present invention is generally preferred, wherein the liquid contains an acid, and its total concentration, based on the total volume of the liquid, is in the range of 5 mol / L to 13 mol / L, more preferably 6 mol / L to 12 mol / L, even more preferably 7 mol / L to 11.5 mol / L, and most preferably 8 mol / L to 11 mol / L. This method is preferably applicable to inorganic acids.

[0087] The method of the present invention is preferred in that the liquid contains phosphoric acid, and its concentration, based on the total volume of the liquid, is preferably in the range of 7.4 mol / L to 11.8 mol / L, more preferably 7.8 mol / L to 11.5 mol / L, more preferably 8.2 mol / L to 11.2 mol / L, even more preferably 8.5 mol / L to 11 mol / L, and most preferably in the range of 8.7 mol / L to 10.8 mol / L.

[0088] The method of the present invention is preferred in that the phosphoric acid liquid is the only (mineral) acid. In some cases, the method of the present invention is preferred in that the liquid is substantially free of (preferably does not contain) sulfuric acid.

[0089] The method of the present invention is preferred, wherein the liquid is substantially free of (preferably does not contain) methanesulfonic acid and its salts, preferably substantially free of (preferably does not contain) C1 to C4 alkyl sulfonic acids and their salts, and most preferably substantially free of (preferably does not contain) C1 to C4 sulfonic acids and their salts.

[0090] The method of the present invention is preferred in that the liquid is substantially free of (preferably not containing) bromide anions and iodide anions, preferably substantially free of (preferably not containing) chloride anions, bromide anions and iodide anions, and most preferably substantially free of (preferably not containing) halide anions.

[0091] Only in a few cases is the method of the present invention preferred, wherein the liquid contains an iodine-containing compound.

[0092] The method of the present invention is preferred in that the liquid is substantially free of (preferably does not contain) trivalent chromium ions and hexavalent chromium compounds, and is preferably substantially free of (preferably does not contain) any chromium-containing compounds and ions.

[0093] The method of the present invention is preferred in that the liquid contains alkali metal ions, preferably sodium ions, and the total concentration of the liquid, based on the total volume of the liquid, is preferably in the range of 0.002 mol / L to 0.5 mol / L, and more preferably 0.004 mol / L to 0.3 mol / L.

[0094] The method of the present invention is preferred, wherein during step (C), the liquid has a temperature in the range of 20°C to 65°C, preferably 30°C to 50°C.

[0095] The method of the present invention is preferred in that the liquid in step (A) and the other liquid system after step (C) are acidic, preferably having a pH of 2 or less, more preferably 1 or less, or even more preferably 0.5 or less.

[0096] The method of the present invention is preferred in that, in step (A) and preferably in a further step after step (C), with reference to a temperature of 20°C, the liquid has a density in the range of 1.2 g / cm³ to 1.7 g / cm³, more preferably 1.3 g / cm³ to 1.6 g / cm³, and even more preferably 1.4 g / cm³ to 1.6 g / cm³.

[0097] The method of the present invention is preferred, wherein, in the liquid after step (C), based on the total volume of the liquid, the manganese substance having a second oxidation state (preferably permanganate ion) has a concentration in the range of 0.004 mol / L to 0.09 mol / L, more preferably 0.005 mol / L to 0.075 mol / L, more preferably 0.006 mol / L to 0.06 mol / L, even more preferably 0.007 mol / L to 0.045 mol / L, even more preferably 0.008 mol / L to 0.03 mol / L, and most preferably 0.009 mol / L to 0.019 mol / L.

[0098] The method of the present invention is preferred, wherein the liquid contains water, and preferably the water system is balanced.

[0099] The invention will now be further illustrated by the following examples.

[0100] An etching composition was prepared from a liquid containing approximately 9 to 10 mol / L phosphoric acid, approximately 10 mmol / L permanganate ions, and approximately 2 mmol / L silver(I) ions. Due to its high degree of self-decomposition, the amount of permanganate ions decreased rapidly. The volume of the liquid was approximately 0.5 L.

[0101] To establish an environmentally and ecologically beneficial etching method, the etching composition is subjected to electrolytic re-oxidation as defined in this invention within a recycling processing apparatus. In this processing apparatus, the following different types of single anodes are tested: (a) Platinum-titanium plating as a fabric anode; surface density of approximately 10 m² / L (surface coefficient of approximately 10); geometric surface area of ​​0.2 dm²; tested with anodic current densities of 0.75 A / dm², 1 A / dm², and 1.3 A / dm²; (b) Platinum-plated stainless steel as fabric anode; surface density of about 14 m² / L (surface coefficient of about 14); geometric surface area of ​​0.15 dm²; anode current density of 1 A / dm².

[0102] A lead alloy cathode is used as the cathode. The anode and the cathode are separated by a ceramic permeable barrier to form an anolyte and a catholyte.

[0103] The processing device is filled with a cathode electrolyte consisting of a concentrated phosphoric acid aqueous solution (70% by weight), wherein the solution is the anolyte.

[0104] The distance between the anode and the cathode is approximately 20 mm.

[0105] The anode current density is as mentioned above, while the cathode current density is approximately 10 A / dm².

[0106] When manganese with the first oxidation state comes into contact with the anode, it is continuously oxidized to permanganate ions (i.e., manganese with the second oxidation state). The manganese with the first oxidation state includes particulate manganese oxide.

[0107] Due to its unusually high surface density, the continuous recycling system is highly efficient and requires only a relatively small anode. However, the total concentration of permanganate ions remains constant.

Claims

1. A method for oxidizing a manganese substance in a processing apparatus, the method comprising the steps of: (A) providing a manganese substance having a first oxidation number in the processing apparatus; (B) providing one or more anodes and at least one cathode in the processing apparatus; and (C) applying a current to the anode and the cathode such that at least a portion of the manganese substance having the first oxidation number is anoly oxidized to a manganese substance having a second oxidation number higher than the first oxidation number, characterized in that, based on the total volume of the at least one anode, at least one of the one or more anodes has a surface density of 6 m² / L or greater, wherein the second oxidation number is higher than +4.

2. The method of request item 1, wherein the first oxidation number is +4 or lower.

3. The method of request item 1 or 2, wherein the second oxidation number is +7.

4. The method of claim 1 or 2, wherein the one or more anodes and the at least one cathode are spaced apart from each other in the range of 1 mm to 100 mm.

5. The method of claim 1 or 2, wherein the one or more anodes and the at least one cathode are separated from each other by a permeable barrier.

6. The method of claim 1 or 2, wherein the surface density is 8 m2 / L or greater.

7. The method of claim 1 or 2, wherein the surface density is in the range of 6 m² / L to 100 m² / L.

8. The method of claim 1 or 2, wherein the at least one anode system having a surface density of 6 m² / L or greater is selected from the group consisting of: 3D printed anodes, fabric anodes, foam anodes, stacked monolayer anodes and packed bed anodes.

9. The method of claim 8, wherein the fabric anode comprises braided metal wires and / or braided metal filaments.

10. The method of claim 8, wherein the fabric anodes comprise plain weave anodes and / or plush fabric anodes.

11. The method of claim 8, wherein the 3D printed anodes comprise 3D printed lattice anodes and / or 3D printed sheet anodes.

12. The method of claim 8, wherein the packed bed anode comprises a packing compartment selected from the group consisting of: Raschig ring, Lessing ring, Pall ring, Bialecki ring, Dixon ring, and net balls.

13. The method of claim 1 or 2, wherein the at least one anode having a surface density of 6 m² / L or greater comprises a material selected from the group consisting of: platinum, titanium, niobium, lead, gold, alloys comprising at least one of the above, oxides thereof, and mixtures thereof.

14. The method of claim 1 or 2, wherein the one or more anodes provide a total effective anode surface area A1 and the at least one cathode provides a total effective cathode surface area A2, wherein A1 is greater than A2.

15. The method of request item 14, wherein A1:A2 is in the range of 5:1 to 100:1.