Method for oxidizing manganese species in a treatment device and treatment device

Abstract

This invention relates to a method for processing manganese oxide in a processing apparatus (10) comprising at least one anode unit (20) and at least one cathode (30), wherein the unit comprises at least one anode (21) and is confined by a housing (22) defining a free internal volume (V), wherein (i) the housing comprises at least one permeable barrier (23) and the at least one cathode is located outside the anode unit, or (ii) the at least one anode unit at least partially comprises the at least one cathode, wherein the housing does not comprise a permeable barrier, characterized in that in (i) and (ii), the at least one anode and the at least one cathode have a distance (d) in the range of 0.5 mm to 100 mm. Furthermore, this invention relates to various processing apparatuses (10).

Description

[Technical Field]

[0001] This invention relates to a method for processing manganese oxide in a processing apparatus (10) comprising at least one anode unit (20) and at least one cathode (30), wherein the unit comprises at least one anode (21) and is confined by a housing (22) defining a free internal volume (V), wherein (i) the housing comprises at least one permeable barrier (23) and the at least one cathode is located outside the anode unit, or (ii) the at least one anode unit at least partially comprises the at least one cathode, wherein the housing does not comprise a permeable barrier, characterized in that in (i) and (ii), the at least one anode and the at least one cathode have a distance (d) in the range of 0.5 mm to 100 mm. Furthermore, this invention further relates to individual processing apparatuses (10). [Previous 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 a metal layer system on a non-metallic / non-conductive substrate is demanding. Typically, various methods begin with surface finishing of the substrate surface, commonly referred to as etching. Usually, a delicate balance is required to ensure sufficient surface roughening without causing 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). Although 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 active manganese replenishment. 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 device 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] US 4,911,802 A refers to an electrolytic oxidation method for producing alkali metal permanganates.

[0011] US 3,062,734 A refers to an electrolytic cell and an electrode used therein, comprising a plurality of adjacent closed dipole electrolytic cells.

[0012] US 5,660,712 A refers to a method for producing potassium permanganate from manganese dioxide ore, wherein the ore containing manganese dioxide is oxidized with a potassium hydroxide feed solution and oxygen.

[0013] US 3,293,160 A refers to a method for producing manganate and / or permanganate by electrolyzing an alkaline solution using pure or substantially pure manganese metal as the anode.

[0014] US 5,062,930 A refers to a method and apparatus for electrolyzing permanganate, comprising manganese dioxide adhering to a cathode surface, which eliminates unwanted reduction reactions at the cathode during electrolysis, thereby increasing the permanganate production efficiency.

[0015] However, there is a continued need to further improve the efficiency of individual regeneration methods and provide more compact devices.

[0016] Objective of the Invention Therefore, the objective of the present invention is to provide a method for efficiently oxidizing manganese materials in a processing apparatus and various processing apparatuses having a compact design. Preferably, the objective is to provide a method and apparatus, which are specifically suitable for processing (i.e., recycling) acidic manganese-based etching compositions (specifically containing permanganates) with excellent efficiency. [Summary of the Invention]

[0017] The above-mentioned objective is achieved by a method for oxidizing manganese in a processing apparatus (10), the method comprising the following steps: (A) providing at least one manganese substance having an oxidation number less than +7 in a liquid in the processing apparatus, (B) providing at least one anode unit (20) and at least one cathode (30) in the processing apparatus, wherein the unit includes at least one anode (21) and is confined by a housing (22) defining a free internal volume (V), (C) applying an electric current to the at least one anode and the at least one cathode such that at least a portion of the at least one manganese substance is anodicly oxidized to manganese with an oxidation number of +7, wherein (i) the housing includes at least one permeable barrier (23) and the at least one cathode is located outside the anode unit, or (ii) the at least one anode unit at least partially includes the at least one cathode, wherein the housing does not include a permeable barrier, characterized in that in (i) and (ii), the at least one anode and the at least one cathode have a distance (d) in the range of 0.5 mm to 100 mm.

[0018] In this invention, the processing apparatus (10) allows for highly efficient anodizing of manganese materials with an oxidation number below +7. Furthermore, at least one anode unit (20) allows for a very compact design, which forms the basis for improved efficiency. Therefore, this invention is well-suited for efficiently processing acidic manganese-based etching compositions because the volume required in the processing apparatus is relatively low compared to the volume of the corresponding etching composition. For example, in conventional techniques, the volume in individual processing apparatuses is approximately equal to the volume of the etching composition used. Conversely, in the method of this invention, the volume processed in the processing apparatus is significantly lower than the volume of the etching composition. Therefore, the so-called dead volume is significantly reduced compared to conventional methods and apparatuses.

[0019] The method of the present invention is preferred, wherein the liquid provided in step (A) has a volume of 50% or less of the total liquid of the liquid provided in step (A), preferably 40% or less, and most preferably 30% or less.

[0020] In the context of this invention, it is essential that at least one cathode is located outside the anode unit or contained within a housing. In each case, this means that the at least one cathode is constructed (at least primarily) around (in the sense of surrounding) at least one anode. In other words, the at least one cathode at least primarily surrounds or encircles the at least one anode, wherein this wording does not limit the overall arrangement to circular. This basic anode / cathode arrangement can also be described as follows: with reference to the center point in the anode unit, the distance from the at least one anode to the center point is less than the corresponding distance from the corresponding at least one cathode. Therefore, the method of the present invention is preferred, wherein the at least one anode is closer to the center of the anode unit than the corresponding at least one cathode, preferably the at least one anode is located at the center of the anode unit.

Implementation Method

[0025] In the method of the present invention, there are two alternative embodiments (i) and (ii), wherein embodiment (i) includes at least one permeable barrier and embodiment (ii) does not. In embodiment (i), due to the presence of at least one permeable barrier, a cathodic electrolyte is formed / present around at least one cathode and an anodic electrolyte is formed / present around at least one anode, respectively. They are permeably separated from each other by the at least one permeable barrier.

[0026] Another advantage of the method of the present invention is its high flexibility. The processing device used in the method of the present invention can be used in both embodiments without requiring a great deal of effort to switch between embodiments (i) and (ii).

[0027] According to embodiment (i), the housing includes at least one permeable barrier and at least one cathode is located outside the anode unit. This embodiment is also preferably referred to as a membrane method (if the at least one permeable barrier comprises a membrane). This means that the at least one cathode is not directly part of the anode unit or its housing but is located (i.e., placed, arranged) outside the anode unit (but within the processing apparatus). However, by means of the permeable barrier, current can flow regardless of the housing, causing at least one manganese substance to be anoly oxidized to a manganese substance having an oxidation number of +7. Preferably, the liquid system (i.e., corresponding to) the anolyte.

[0028] In embodiment (ii), due to the lack of individual permeable barriers and the fact that the housing at least partially contains at least one cathode, there is no or no distinction between the cathode electrolyte and the anolyte.

[0029] Typically, the maximum volume of the liquid (i.e., the anolyte present in the preferred embodiment (i)) substantially corresponds to the free internal volume (V). Preferably, this liquid system is used to etch the composition, i.e., preferably provided as the etch composition used in step (A) and returned as a refresh / recycled etch composition after step (C).

[0030] Preferably (regardless of embodiment (i) or (ii)), the free internal volume (V) corresponds to the total internal housing volume minus the volume (i.e., tare volume) of at least one anode located inside the housing (including, for example, its mounting components), thus reducing the total internal housing volume. In other words, the free internal volume (V) is more preferably the volume in which the liquid can occupy the largest possible space within at least one anode unit.

[0031] The method of the present invention is preferred, wherein the cathode electrolyte contains an inorganic acid, preferably phosphoric acid, more preferably 20% to 90% phosphoric acid, even more preferably 30% to 80% phosphoric acid, and most preferably 40% to 70% phosphoric acid.

[0032] In embodiment (i), all manganese materials are preferably separated from at least one cathode. This preferably means that the permeable barrier is substantially impermeable to negatively charged or neutral manganese materials.

[0033] The method of the present invention is preferred, wherein at least one permeable barrier is an ion-selective permeable barrier, preferably an ion-selective permeable membrane.

[0034] The method of the present invention is preferred, wherein at least one permeable barrier is a cation-selective permeable barrier, preferably a cation-selective permeable membrane. Therefore, it is best to be permeable only to cations.

[0035] Preferably, in the method of the present invention, at least one permeable barrier is not a mineral. Preferably, in the method of the present invention, the at least one permeable barrier is substantially free of (preferably not containing) ceramics.

[0036] Preferably, in the method of the present invention, at least one permeable barrier is organic. Preferably, the at least one permeable barrier is organic and contains fluorine (preferably fluorinated), most preferably organic and perfluorinated. Preferably, the at least one permeable barrier is a Nafion-type membrane; however, the at least one membrane is not particularly limited to this specific brand. Therefore, the aforementioned preferences also apply to preferred ion-selective (preferably cation-selective) permeable barriers and preferred ion-selective (preferably cation-selective) permeable membranes. The membrane (preferably such organic membranes) is very thin and therefore contributes positively to a relatively short distance (d), and thus to a compact design of at least one anode unit.

[0037] In the context of this invention, an advantage is that the total area of ​​the permeable barrier can be kept relatively low due to the very compact design.

[0038] In step (C) of the method of the present invention, a current, preferably an electrical current, is applied. This current and the associated electric field generally affect the migration direction of individual ions present in the liquid. Thus, negatively charged manganese substances are forced to migrate to at least one anode.

[0039] The permeable barrier present in Example (i) combined with the current generally results in, or even more completely, preventing negatively charged manganese material from contacting at least one cathode. In the absence of current, the permeable barrier preferably significantly inhibits / reduces the mixing of the anolyte and catholyte with each other (preferably the transport of anions into the catholyte). This preferably means that the permeable barrier (preferably a cation-selective permeable membrane) inhibits / avoids the transport of anions from the anolyte to the catholyte. Therefore, the transport of negatively charged manganese material (e.g., MnO4-, PO43-, HPO42-, H2PO4-) is significantly inhibited when no current is used, and even more so when current is used. Furthermore, the transport of particulate uncharged MnO2 is also preferably avoided or at least significantly inhibited. Conversely, the permeable barrier freely and primarily allows the transport / migration of water molecules, preferably water and hydrated hydrogen ions.

[0040] The method of the present invention is preferred, wherein in (ii), at least one cathode system is at least partially integrated into the housing, preferably at least partially extending from the outside through the housing into the interior toward at least one anode.

[0041] According to embodiment (ii), the housing at least partially includes (preferably integrated) at least one cathode, wherein the housing does not contain (i.e., has no) a permeable barrier. This embodiment is also preferably referred to as a membrane-free method. Preferably, the entire housing does not contain a permeable barrier. In this embodiment, the at least one cathode is preferably at least partially integrated into the housing. This also means that the at least one cathode (preferably at least partially) is preferably part of the housing itself and therefore (preferably at least partially) preferably confines at least one anode unit as part of the housing. In addition, the at least one cathode (preferably at least partially) is included (preferably integrated) into the housing and preferably exposes at least partially of the cathode region to the interior of the housing. As mentioned, in this embodiment, it is preferable not to form separate cathode electrolytes and anode electrolytes but only liquids. In this embodiment, it is preferable that all manganese materials are substantially in contact with the at least one anode and the at least one cathode. Therefore, the method of the present invention according to embodiment (ii) is preferred, wherein in step (C), each manganese material is at least partially in direct contact with the at least one cathode. However, from the perspective of current efficiency, this is not ideal. Our experiments have shown that, compared to a method utilizing a permeable barrier (i.e., Example (i)), lower current efficiency is achieved due to the unwanted decomposition of manganese (with an oxidation state of +7) caused by the level of unwanted cathode side reactions. However, our experiments have also shown that Example (ii) offers a greater advantage if the liquid contains other metal ions besides manganese (such as silver ions). In this example, unwanted cathode silver deposition can be prevented or at least reversed, preventing silver (or possibly other metal ions besides manganese) from remaining permanently dissolved or at least redissolving at certain time intervals.

[0042] The method of the present invention is preferred, wherein (d) is in the range of 1 mm to 90 mm, more preferably 2 mm to 80 mm, even more preferably 3 mm to 70 mm, even more preferably 4 mm to 60 mm, and most preferably 5 mm to 50 mm.

[0043] In the method of the present invention, the aforementioned content regarding (d) is generally preferred.

[0044] In the method of the present invention, it is generally preferred that the distance (d) is defined as the shortest distance between at least one anode and the nearest (preferably corresponding) at least one cathode. In other words, the distance (d) is preferably the shortest external distance between the at least one anode and the nearest (preferably corresponding) at least one cathode. The term "external" preferably means that the outermost edge of the at least one anode directly faces the outermost edge of the nearest at least one cathode. Most preferably, the distance (d) is the shortest average external distance between the at least one anode and the nearest (preferably corresponding) at least one cathode. This is preferred if the at least one anode and the at least one cathode are arranged parallel to each other. For clarity, refer to Figures 1 to 3.

[0045] Particularly in embodiment (i), the method of the present invention is preferred, wherein (d) is in the range of 9 mm to 70 mm, more 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. In this embodiment, the minimum distance (d) is generally larger than that in embodiment (ii) because at least one cathode is located outside the anode unit (i.e., outside the housing), such that the housing is located between the at least one cathode and the at least one anode. Therefore, the method of the present invention is preferred, wherein the distance (d) has a minimum distance, provided that the minimum distance (d) in (i) is higher than that in embodiment (ii). Furthermore, in embodiment (i), at least one permeable barrier is located between the at least one anode and the at least one cathode without directly contacting the anode and cathode. However, the thickness of the permeable barrier is preferably negligible and therefore has no substantial effect on the distance (d).

[0046] Particularly in embodiment (ii), the method of the present invention is preferred, wherein (d) is in the range of 1 mm to 70 mm, more preferably 2 mm to 60 mm, more preferably 3 mm to 50 mm, even more preferably 4 mm to 30 mm, and most preferably 5 mm to 20 mm. In this embodiment, a relatively low distance (d) is generally maintained because the housing at least partially contains at least one cathode. Therefore, the minimum value of the distance (d) is relatively low. Compared to embodiment (i), which preferably has a higher minimum value of the distance (d), this has the advantage of requiring less voltage.

[0047] The method of the present invention is preferred, wherein at least one anode comprises an anode layer, preferably a stack of three or more anode layers (25), more preferably the stack comprises three to 300 anode layers, even more preferably four to 200 anode layers, even more preferably six to 100 anode layers, most preferably eight to 60 anode layers, and even more preferably nine to 30 anode layers.

[0048] It is quite unexpected to see in the text of this invention that a very compact design, such as an anode designed to provide sufficiently high current efficiency / turnover for a stack of multiple anode layers, is preferred if the space between individual anode segments is very small; ideally, if the number of individual anode layers in the stack is relatively high and therefore the space between them is relatively small. It is generally believed that in such cases, a very high and detrimental shielding effect occurs, for example, specifically, more individual anode segments are continuously positioned toward at least one cathode. However, although this shielding effect does occur, it is surprisingly low and surprisingly tolerable to facilitate a relatively large total effective anode surface area. Surprisingly, despite the assumption that this anode provides a Faraday cage-like barrier, the electric field has a penetration depth that results in sufficient efficiency and turnover. In other words, such anodes unexpectedly allow for an extremely compact and dense anode structure and therefore a relatively low processing device. This further allows for the minimization of the free internal volume (V).

[0049] In this preferred layer stack, the layer stack preferably includes at least one inner anode layer and at least one outer anode layer. The at least one inner anode layer faces another inner anode layer or is at least on one side of at least one outer layer. However, if the layer stack contains exactly two anode layers, then they are all simultaneously at least one outer anode layer. The same applies if at least one anode comprises or is a single anode layer.

[0050] In some cases, the method of the present invention is preferred, wherein at least one anode comprises or is a single anode layer, which also provides a large total effective anode surface area, preferably equivalent to a large total effective anode surface area obtained by means of a preferred layer stack.

[0051] As mentioned, the method of the present invention is preferred, wherein the distance (d) is defined as the shortest distance between at least one anode and the nearest (preferably corresponding) at least one cathode. The method of the present invention is even more preferred, wherein the distance (d) is defined as the shortest distance between the outermost anode layer of the stacked layers and the nearest (preferably corresponding) at least one cathode.

[0052] Generally, it is preferred that the distance (d) is a constant distance. This preference means that (d) represents the distance between at least one anode and at least one cathode (which are arranged in parallel to each other).

[0053] In the method of the present invention, at least one anode system is preferably horizontally or vertically oriented (compare Figures 1 and 2). The method of the present invention is more preferably wherein the at least one anode system is vertically oriented (compare Figure 1). This is best suited for the anode layer of a stacked layer (25). However, in some other cases, the method of the present invention is preferred wherein the at least one anode system is horizontally oriented (compare Figure 2). This is also best suited for the anode layer in a stacked layer (25). Our experiments have shown that vertical orientation provides improved current efficiency in many cases and is therefore preferred. It is assumed that in this case, the liquid has improved perfusion through at least one anode unit, and the gas formed can easily escape without adsorbing onto the anode surface. Furthermore, this method is also associated with lower cost.

[0054] The method of the present invention is preferred, wherein in embodiment (i), at least one anode comprises a stack of 2 to 100 anode layers, more preferably 3 to 80 anode layers, more preferably 4 to 60 anode layers, even more preferably 5 to 40 anode layers, and most preferably 6 to 30 anode layers (25).

[0055] The method of the present invention is preferred, wherein in embodiment (ii), at least one anode comprises a stack of 2 to 300 anode layers, preferably 5 to 260 anode layers, more preferably 7 to 220 anode layers, even more preferably 9 to 170 anode layers, and most preferably 12 to 130 anode layers (25). However, in many cases, the number of anode layers is preferably as defined above with respect to embodiment (i).

[0056] The method of the present invention is preferred, wherein in the layer stack, the anode layers have a distance (m) between each other in the range of 0.5 mm to 20 mm, preferably 1 mm to 15 mm, more preferably 2 mm to 12 mm, even more preferably 3 mm to 10 mm, and most preferably 4 mm to 9 mm.

[0057] Preferably, the distance (m) is fixed by means of a spacer (26). More preferably, the distance (m) is (substantially) constant, and preferably (substantially) constant between all anode layers in the stack.

[0058] In some cases, the optimal distance (m) is in the range of 1 mm to 6 mm, and more preferably in the range of 1.5 mm to 4 mm.

[0059] The method of the present invention is preferred, wherein at least one anode (preferably a stacked layer) comprises a sheet, a mesh, a woven mesh and / or expanded metal (i.e., a metal mesh).

[0060] Within the text of this invention, it is generally preferred to provide at least one anode having a relatively high total effective anode surface area. At least one anode (preferably a layer stack) preferably satisfies this desired and preferred characteristic in the aforementioned form. In many cases, the method of this invention is preferred, wherein the at least one anode comprises expanded metal (metal grid; also known as "Streckmetall"). Preferably, the layer stack (25) comprises expanded metal as the anode layer.

[0061] The method of the present invention is preferred, wherein at least one anode (an individual anode layer in a preferred layer stack) has a surface coefficient of 1 or greater, preferably 1.4 or greater, even more preferably 1.7 or greater, even more preferably 2 or greater, most preferably 2.1 or greater, even more preferably 2.2 or greater.

[0062] In the context of this invention, the surface coefficient represents a parameter that defines the total effective surface area of ​​each geometric area.

[0063] For example, a plate (i.e., a surface) with a geometry of 1 m² typically has a surface coefficient of 2 (for simplicity, the area of ​​the cut edges is ignored), resulting in a total effective surface area of ​​2 m² (including the front and back sides). Therefore, this surface coefficient has no dimension / unit. If, for example, the plate has holes and the mesh has openings of a specified number and size, a surface coefficient lower than or even higher than 2 is typically obtained. However, the surface coefficient of commercially available meshes today typically does not exceed 2.5.

[0064] In the method of the present invention, in many cases, it is preferable to obtain a relatively high effective anode surface area by utilizing layer stacking. On the other hand, the shielding effect needs to be as low as possible to achieve the best possible efficiency.

[0065] In the context of this invention, the surface coefficient as defined above is best applied to individual anode layers in a stack of layers.

[0066] The method of the present invention is also preferred, wherein, in addition to the anodes mentioned above, at least one anode is preferably selected from the group consisting of: 3D printing anodes, fabric anodes, foam anodes, and filled bed anodes. Typically, based on the total volume of the at least one anode, such anodes have a relatively high effective surface area per volume, preferably 6 m² / L or greater. This is also referred to as surface density, which represents the total effective surface area per geometric volume.

[0067] The method of the present invention is preferably 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, even more preferably 10 m2 / L to 50 m2 / L, even more preferably 12 m2 / L to 40 m2 / L, even more preferably 14 m2 / L to 30 m2 / L, and most preferably 16 m2 / L to 22 m2 / L.

[0068] The method of the present invention is preferred, wherein the fabric anode comprises braided metal wire and / or braided metal filament.

[0069] The method of the present invention is preferred, wherein the fabric anode includes a plain weave fabric anode and / or a plush fabric anode.

[0070] The method of the present invention is preferred, wherein the 3D printing anode includes a 3D printing lattice anode and / or a 3D printing sheet anode.

[0071] The method of the present invention is preferred, wherein the foam anode comprises a sponge anode.

[0072] 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.

[0073] The method of the present invention is preferred, wherein at least one anode comprises platinum, titanium, niobium, lead, gold, an alloy comprising at least one thereof, an oxide thereof, and / or a mixture thereof; preferably at least one of platinum, titanium, and gold.

[0074] In fact, not all anode materials are suitable for the purposes achieved by the method of the present invention. Because the liquid is preferably highly acidic and because of the strong oxidizing properties of manganese, at least one anode (and its individual materials) must be carefully selected. The minimum requirement is that the individual materials are (e)chemically inert to the liquid system. Typically, the aforementioned anodes are resistant at least for a certain period of time. The method of the present invention is preferred, wherein the at least one anode comprises a platinum-plated anode and / or a platinum-plated anode, preferably a platinum-plated titanium anode and / or a platinum-plated niobium anode.

[0075] In some cases, the method of the present invention is preferred, wherein at least one anode comprises lead and / or a lead alloy. The lead alloy preferably comprises tin and / or silver as alloying elements. However, our experiments have shown that excellent efficiency is obtained using at least one anode comprising platinum, preferably at least one anode comprising a platinum-plated anode and / or a platinum anode. This preference also applies to embodiments (i) and (ii), respectively.

[0076] The method of the present invention is generally preferred in that at least one cathode comprises titanium, platinum, niobium, lead, an alloy comprising at least one of the above, an oxide thereof, stainless steel, and / or a mixture thereof. Generally, the method of the present invention is preferred in that the at least one cathode is made of a wide range of materials, provided that each material is preferably acid-resistant, sufficiently stable against hydrogen embrittlement, and / or chemically resistant to liquids (depending on the embodiment used).

[0077] In some cases, the method of the present invention is preferred, wherein the at least one cathode system is the same as the at least one anode in preferred embodiment (ii). However, in other cases, the at least one cathode system is preferred to be different from the at least one anode, preferably in embodiment (i), but also in embodiment (ii).

[0078] The method of the present invention is preferred, wherein in embodiment (i), at least one cathode comprises platinum, titanium, lead, nickel, an alloy comprising at least one of them, an oxide thereof, stainless steel, and / or a mixture thereof. Stainless steel is preferred; it exhibits excellent resistance to phosphoric acid, which is the preferred cathodic electrolyte in this embodiment. Furthermore, our experiments have shown that cathode current protection of at least one cathode allows the use of even lower resistivity materials. This general principle of cathode protection is also preferably applicable to embodiment (ii).

[0079] However, in embodiment (ii), a cathode material that is very electrochemically inert is preferred. In this case, it is preferable that at least one cathode comprises titanium, platinum, niobium, lead, an alloy comprising at least one of them, its oxide, stainless steel, and / or a mixture thereof. In some cases, the method of the present invention is preferred, wherein the at least one cathode comprises a platinum-plated cathode and / or a platinum-plated cathode, preferably a platinum-plated titanium cathode and / or a platinum-plated niobium cathode. In other cases, the method of the present invention is preferred, wherein the at least one cathode comprises stainless steel. In some cases, stainless steel is preferred for cathode protection and can be used in embodiment (ii) of the method according to the present invention.

[0080] The method of the present invention is generally preferred, wherein at least one cathode comprises one cathode layer or two, three or more than three cathode layers, preferably a stack of two cathode layers. In embodiment (ii) of the method of the present invention, the cathode layer stack (preferably a stack of two cathode layers) is more preferred.

[0081] The method of the present invention is preferred in that the cathode layers in the layer stack are electrically isolated from each other. This preferably allows each cathode layer to have a different current source.

[0082] The method of the present invention is generally preferred, wherein at least one cathode comprises a sheet, a mesh, a braided mesh, and / or expanded metal. This is most suitable for embodiment (i).

[0083] The method of the present invention is preferred, wherein at least one cathode and at least one anode system are vertically oriented, preferably perpendicular and parallel to each other.

[0084] The method of the present invention is preferred, wherein at least one anode provides a total effective anode surface area A1 and at least one cathode provides a total effective cathode surface area A2, wherein A1 is greater than A2.

[0085] In the context of this invention, "total effective surface area" refers to the area that can be used to participate in electrochemical redox reactions.

[0086] The method of the present invention is preferred, wherein in embodiment (ii), at least a portion (preferably a portion) of at least one cathode penetrates the outer casing into the interior, thereby exposing a plurality of cathode points (31) to the interior facing the at least one anode, and A2 is formed by these points. If only these points are exposed to the anode unit facing the at least one anode, these points effectively minimize the total effective cathode surface area.

[0087] Preferably, the dots are finally evenly distributed on a portion of the outer casing. In this way, A2 is evenly distributed within the anode unit.

[0088] In some cases, the method of the present invention is preferred, wherein the plurality of cathode points are in the same plane as the interior of the housing.

[0089] The method of the present invention is more preferably wherein at least one portion (preferably portion) penetrates from the outside of the housing into the inside of the cathode facing at least one anode and comprises a stack of at least two cathode layers (compare Figure 3).

[0090] The method of the present invention is preferred, wherein a plurality of cathode points form first and second groups of cathode points (32 and 33 respectively, see Figure 3), each group preferably having its own current. This preference means that the first and second groups are electrically isolated from each other. Furthermore, this preference allows for the temporary shutdown of one of the groups to operate both with different currents, or the reversal of the current in one of the groups compared to the other. Our experiments have shown that if silver ions are used in the liquid, this is of great benefit in avoiding, for example, the deposition of metallic silver.

[0091] The method of the present invention is 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.

[0092] This is generally preferred in the method of the present invention.

[0093] More preferably, specifically in embodiment (i), it is not necessary to specifically consider a certain ratio, as long as A1 is greater than A2. Preferably, 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.

[0094] However, in embodiment (ii), the method of the present invention is preferred, wherein the ratio of A1:A2 is at least 10:1, preferably at least 20:1, more preferably at least 30:1, and most preferably at least 40:1. The method of the present invention is also preferred, wherein the ratio of A1:A2 is in the range of 10:1 to 100:1, preferably 20:1 to 70:1, more preferably 30:1 to 50:1, and most preferably 35:1 to 45:1. This is preferable for carrying out embodiment (ii) with preferred high current efficiency and for sufficiently suppressing unwanted cathode side reactions that destroy the desired manganese material. Furthermore, it provides an optimal balance between current efficiency and energy consumption.

[0095] In the preferred embodiment of the method of the present invention, A1 is in the range of 10 dm2 / dm3 to 100 dm2 / dm3, more preferably 15 dm2 / dm3 to 85 dm2 / dm3, more preferably 20 dm2 / dm3 to 70 dm2 / dm3, even more preferably 25 dm2 / dm3 to 60 dm2 / dm3, and most preferably 30 dm2 / dm3 to 50 dm2 / dm3, based on the free internal volume (V).

[0096] 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 free internal volume of at least one anode unit). In the method of this invention, a relatively high anode density is required to efficiently oxidize manganese materials having an oxidation number below +7. In fact, the aforementioned anode density (specifically, preferred and optimal) is generally considered high. It is a parameter characterizing the close and dense packing of at least one anode in at least one anode unit. This principle is preferably applied to Examples (i) and (ii).

[0097] The method of the present invention is preferred, wherein the processing device and / or at least one anode unit (preferably at least one anode unit) has at least one inner surface comprising, preferably, polyvinylidene fluoride (PVDF) and / or polytetrafluoroethylene (PTFE), or constituted therewith.

[0098] Our experiments have shown that these materials have the required chemical resistance to prevent damage and harm to the processing apparatus and at least one anode unit from harsh conditions from liquids (e.g., by means of dissolution and / or etching).

[0099] As mentioned above, in step (A), at least one manganese substance having an oxidation number of less than +7 is provided in the liquid.

[0100] The method of the present invention is preferred, wherein in step (A), the liquid is obtained from an etching chamber used for etching a non-metallic substrate, preferably a plastic substrate. As mentioned above, the liquid is preferably an etching composition, preferably after contact with the non-metallic substrate, preferably the plastic substrate.

[0101] The method of the present invention is preferred, wherein in step (A), in the liquid, at least one manganese substance having an oxidation state of less than +7 comprises a manganese substance having an oxidation state of +14, preferably MnO2. More preferably, the manganese substance having an oxidation state of +14 constitutes more than 50 mol% of all manganese substances in the liquid before step (C), preferably at least 75 mol%. Preferably, the MnO2 is in particulate form, preferably in the form of colloidal particles. This preferably includes its optional aggregates.

[0102] The method of the present invention is preferred, wherein the 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 in ABS and ABS-PC.

[0103] The method of the present invention is preferred, wherein in step (C), the manganese material having an oxidation number of +7 comprises permanganate ions, preferably permanganate ions. Typically, the permanganate is reduced to a manganese material having a lower oxidation number by etching a plastic substrate, for example, with permanganate, and the plastic material is at least partially oxidized.

[0104] The method of the present invention is preferred, wherein in step (A), based on the total volume of elemental manganese and liquid, at least one manganese substance having an oxidation number of less than +7 has a total concentration in the range of 0.1 g / L to 4 g / L, more preferably in the range of 0.2 g / L to 3 g / L, even more preferably in the range of 0.3 g / L to 2 g / L, and most preferably in the range of 0.4 g / L to 1.5 g / L.

[0105] In step (C) of the method of the present invention, an electric current is applied to anoly oxidize at least a portion of a manganese substance having an oxidation number lower than +7.

[0106] The method of the present invention is preferred, wherein at least a portion of the manganese material that was anodized to a manganese material having an oxidation number of +7 in step (C) is transferred back into the etching chamber of the etched plastic substrate.

[0107] Preferably, the method of the present invention is a method for recycling permanganate ions. In this context, "recycling" means re-oxidizing (preferably used) manganese material to an oxidation state of +7 and subsequently reusing it for etching. The method of the present invention is preferably carried out continuously.

[0108] In some cases, the method of the present invention is preferred, wherein the processing apparatus 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 is at least partially integrated into the etching chamber. This preferably means that the processing apparatus is internal to the etching chamber.

[0109] Preferably, in step (C), the current has a current density in the range of 0.1 A / dm² to 10 A / dm², more 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, this anode current density is relatively low to avoid / reduce the generation of unwanted anode oxygen, which further reduces current efficiency.

[0110] 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, a relatively high cathode current density is required. This generally leads to the production of hydrogen. Although this is generally undesirable, within the context of the present invention, it suppresses the undesirable cathode decomposition reaction of the desired manganese material. This is best suited to Example (ii).

[0111] The method of the present invention is preferred, wherein the cathode current density in embodiment (ii) is higher than the cathode current density in embodiment (i).

[0112] In embodiment (i), 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.

[0113] In embodiment (ii), 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, and most preferably 16 A / dm² to 50 A / dm². In some cases, the cathode current density is preferably in the range of 18 A / dm² to 35 A / dm².

[0114] The method of the present invention is preferred, wherein the liquid contains an acid, preferably an inorganic acid, and most preferably phosphoric acid.

[0115] The method of the present invention is preferred, wherein after step (C), the liquid preferably comprises, (a) water, (b) 0.0025 mol / L to 0.1 mol / L of manganese having an oxidation state of +7, preferably permanganate ions, (c) 7 mol / L to 12 mol / L phosphoric acid, (d) 0 to 0.1 mol / L silver(I) ions, and (e) 0 or less than 10 ppm manganese(II) ions.

[0116] The liquid used in the method of the present invention comprises water. Preferably, in the method of the present invention, (a), (b), (c), (d), and (e) constitute 90% or more, more preferably 92% or more, more preferably 94% or more, even more preferably 96% or more, and most preferably 98% or more, of the total weight of the liquid. Preferably, in the method of the present invention, the remainder of the liquid is water.

[0117] 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 an oxidation state of +7 (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.

[0118] The method of the present invention is preferred, wherein in step (A), in the liquid, based on the total volume of the liquid, all manganese substances together 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 includes residual amounts of manganese substances with an oxidation state of +7 (if present), preferably permanganate ions, and manganese substances with an oxidation state of less than +7. This is preferably applicable to the liquid in step (A) and after step (C).

[0119] The method of the present invention is preferred in that, in the liquid, based on the total volume of the liquid, phosphoric acid has a concentration in the range of 7.4 mol / L to 11.8 mol / L, more preferably 7.8 mol / L to 11.5 mol / L, even 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 8.7 mol / L to 10.8 mol / L.

[0120] The method of the present invention is preferred in that the phosphoric acid is the only (mineral) acid in the liquid. Specifically, it is phosphoric acid and preferably lacks other strong mineral acids, which significantly slows down the further reduction of manganese substances (such as MnO2) with an oxidation state of +IV to an oxidation state below +IV. This is excellent. This is also preferred because the liquid contains a relatively low amount of manganese(II) ions.

[0121] In some cases, the method of the present invention is preferred, wherein in the liquid, based on the total volume of the liquid, phosphoric acid has a concentration in the range of 9.2 mol / L to 10.5 mol / L, more preferably 9.3 mol / L to 10.4 mol / L, and even more preferably 9.4 mol / L to 10.3 mol / L.

[0122] In some cases, the method of the present invention is preferred, wherein the liquid contains silver (I) ions. Silver ions are preferred to better catalyze the electrolytic re-oxidation.

[0123] The method of the present invention is preferred in that the silver (I) ions in the liquid have a concentration in the range of 0.0001 mol / L to 0.09 mol / L, more preferably 0.0002 mol / L to 0.07 mol / L, more preferably 0.0005 mol / L to 0.05 mol / L, even more preferably 0.0007 mol / L to 0.03 mol / L, and most preferably 0.001 mol / L to 0.01 mol / L.

[0124] Preferably, in step (A), the liquid is substantially free of, and preferably does not contain, manganese(II) ions. In some cases, its concentration is preferably relatively low, preferably not exceeding 10 ppm, based on the total volume of the liquid. This preference generally applies to the liquid used in the method of the present invention.

[0125] The method of the present invention is preferred in that the liquid contains alkaline ions, preferably sodium ions, and the concentration of the liquid is preferably in the range of 0.002 mol / L to 0.5 mol / L, more preferably 0.004 mol / L to 0.3 mol / L, based on the total volume of the liquid.

[0126] The method of the present invention is preferred in that the liquid is substantially free of, preferably free of, methanesulfonic acid and its salts, preferably substantially free of, preferably free of C1 to C4 alkyl sulfonic acids and their salts, most preferably substantially free of, preferably free of C1 to C4 sulfonic acids and their salts.

[0127] The method of the present invention is preferred in that the liquid is substantially free of, preferably free of, bromide anions and iodide anions, preferably substantially free of, preferably free of chloride anions, bromide anions and iodide anions, most preferably substantially free of, and preferably free of halogen anions.

[0128] The method of the present invention is preferred in that the liquid is substantially free of, preferably free of, trivalent chromium ions and hexavalent chromium compounds, and preferably substantially free of, preferably free of any compounds and ions containing chromium.

[0129] The method of the present invention is preferred, wherein the liquid is substantially free of, and preferably free of, sulfuric acid.

[0130] 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.

[0131] The method of the present invention is preferred in that the liquid system in step (A) and after step (C) is acidic, preferably having a pH of 2 or lower, more preferably 1 or lower, or even more preferably 0.5 or lower.

[0132] The method of the present invention is preferred, wherein in step (A) and after step (C), at 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. This preferred density is a result of the large amount of phosphoric acid and particulate and / or colloidal MnO₂.

[0133] Furthermore, the present invention refers to various processing apparatuses, preferably used for oxidizing manganese substances having an oxidation number lower than +7 to manganese substances having an oxidation number of +7, the processing apparatus comprising at least one anode unit (20) and at least one cathode (30), wherein the unit comprises at least one anode (21) and the unit is confined by a housing (22) defining a free internal volume (V), wherein (i) the housing comprises at least one permeable barrier (23) and the at least one cathode is located outside the anode unit, or (ii) the housing at least partially comprises the at least one cathode, wherein the housing does not comprise a permeable barrier, characterized in that in (i) and (ii), the at least one anode and the at least one cathode have a distance (d) in the range of 0.5 mm to 100 mm.

[0134] Preferably, the foregoing content regarding the method of the present invention also applies to the processing apparatus of the present invention, and is best defined as the features of the processing apparatus preferably used in the method of the present invention also apply to the processing apparatus of the present invention.

[0135] The present invention will now be further illustrated with reference to the drawings and the following examples.

[0136] 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 was used as an etching composition for etching ABS and ABS-PC substrates at approximately 40°C. The etching time was approximately between 5 and 20 minutes. During etching, the amount of permanganate ions decreased rapidly.

[0137] In order to establish an environmentally and ecologically favorable etching method, the etching composition is continuously supplied as a liquid to the processing unit (10) for recycling by active pumping (not shown).

[0138] In embodiment (i) according to FIG1, the processing apparatus (10) is filled with a cathode electrolyte composed of aqueous concentrated phosphoric acid (70% by weight), wherein the liquid (i.e., the anolyte in this embodiment) is continuously pumped through at least one anode unit (20). The at least one anode unit (20) is a defined compartment containing at least one anode (21) at its center. The at least one anode (21) is provided as a vertically oriented stack comprising a plurality of 8 to 20 anode layers (25), the anode layers being expanded metals having an individual surface area coefficient slightly greater than 2. The at least one anode unit (20) provides a total effective anode surface area A1 of about 40 dm2 / dm3.

[0139] At least one anode unit (20) is constrained by a housing (22) which includes at least one permeable barrier (23) of a nanofiber membrane. Typically, both of these are used on opposite sides of the housing (22) as shown in FIG1. ​​The distance (m) between the plurality of anode layers is fixed by spacers (26) and is approximately 1 to 2 mm.

[0140] Typically, the processing apparatus utilizes 1 to 5 anode units to continuously recover permanganate ions, with an efficiency of approximately 200 L of etching composition recovered per anode unit. In certain cases, 5 anode units in a processing apparatus are used for approximately 600 to 1000 L of etching composition. Typically, the volume of liquid present in at least one anode unit corresponds to the free internal volume (V) as defined above herein.

[0141] At least one cathode (30) is provided outside at least one anode unit, typically surrounding at least one anode unit (20) on the opposite side relative to the at least one anode unit (20). The at least one cathode (30) provides a total effective cathode surface area A2, wherein A1 is significantly larger than A2. The distance (d) between the at least one anode (21) and the at least one cathode (30) is approximately 15 mm.

[0142] Current is applied to the at least one anode (21) and the at least one cathode (30). The anode current density is about 1 A / dm2, and the cathode current density is about 10 A / dm2.

[0143] When flowing through at least one anode unit (20), the liquid comes into contact with the anode layer of the stack (25) and continuously re-oxidizes manganese substances with an oxidation number lower than +7 to permanganate ions (i.e. manganese substances with an oxidation number of +7).

[0144] In the alternative embodiment (i) according to FIG2, the anode layer is provided in a horizontal stack. The current efficiency is observed to be slightly lower than that obtained with a vertically oriented anode layer.

[0145] In the two variations of Example (i), silver (I) ions are supplemented from time to time to compensate not only for drag-out but also for unwanted small amounts of precipitation.

[0146] In embodiment (ii) according to FIG. 3, no permeable barrier (23) is used in the housing (22). Instead, at least one cathode system is at least partially integrated into opposite sides of the housing (22) such that the at least one cathode (30) partially penetrates the housing (22) into the interior toward at least one anode (21). Thereby, a plurality of cathode points (31) are formed, approximately 16 to 60 points on each of the two opposite inner sides of the housing (22) of the at least one anode unit (20). Furthermore, two cathodes (30) are used such that the cathode points of the first group (32) and the second group (33) (from the plurality of cathode points) are present inside the at least one anode unit (20) toward the at least one anode (21). The two cathodes are electrically isolated from each other. Repeated reversal of the cathode current dissolves the silver precipitate and thus substantially avoids silver precipitation. Losses caused only by dragging are compensated over time intervals. Therefore, the consumption of silver is significantly reduced.

[0147] There is no difference between the anolyte and the catholyte. The catholy current density is approximately 50 A / dm², and is therefore significantly higher than the current density in Example (i). The distance (d) between at least one anode (21) and at least one cathode (30) is approximately 10 mm.

[0148] In various embodiments, a liquid containing re-oxidized permanganate ions is returned as an etching composition.

[0149] In addition, in each case, a very compact anode unit is provided, which allows for the continuous recovery of individual manganese substances in a strongly acidic environment. [Simplified Explanation of the Diagram]

[0021] All figures are schematic diagrams of the processing apparatus (10) used in the method of the present invention, which illustrate the principle of the present invention. They do not necessarily represent actual dimensions and ratios. For simplicity, flowcharts, pipes and valves are not shown and are omitted.

[0022] Figure 1 shows a processing apparatus according to embodiment (i), wherein at least one anode (21) and at least one cathode (30) are vertically oriented and separated by at least one permeable barrier (23) in the housing (22).

[0023] Figure 2 shows a processing apparatus according to embodiment (i), wherein at least one anode (21) is horizontally oriented and separated from at least one cathode (30) by at least one permeable barrier (23) in the housing (22).

[0024] Figure 3 shows a processing apparatus according to embodiment (ii), wherein at least one anode (21) and at least one cathode (30) are oriented perpendicularly to each other and are not separated by a permeable barrier (23). Instead, the housing (22) at least partially includes the at least one cathode (30) and forms a plurality of cathode points (31) including a first set of cathode points (32) and a second set of cathode points (33).

Claims

1. A processing apparatus (10) comprising: at least one anode unit (20) and at least one cathode (30), wherein the unit includes at least one anode (21) and the unit is confined by a housing (22) defining a free internal volume (V), wherein (i) the housing includes at least one permeable barrier (23) and the at least one cathode is located outside the anode unit, or (ii) the housing at least partially includes the at least one cathode, wherein the housing does not include the permeable barrier, characterized in that in (i) and (ii), the at least one anode and the at least one cathode have a distance (d) in the range of 0.5 mm to 100 mm.

2. The processing apparatus (10) of claim 1, wherein the at least one permeable barrier is an ion-selective permeable barrier.

3. The processing apparatus (10) of claim 1, wherein in (ii), the at least one cathode system is at least partially integrated into the housing.

4. The processing device (10) of any one of the claims 1 to 3, wherein (d) is in the range of 1 mm to 90 mm.

5. The processing apparatus (10) of any one of claims 1 to 3, wherein the at least one anode comprises a stack of anode layers (25).

6. The processing apparatus (10) of claim 5, wherein in the layer stack, the anode layers have a distance (m) between each other in the range of 0.5 mm to 20 mm.

7. The processing apparatus (10) of any one of claims 1 to 3, wherein the at least one anode comprises a sheet, a mesh, a woven mesh and / or expanded metal.

8. The processing apparatus (10) of any one of claims 1 to 3, wherein the at least one anode has a surface coefficient of 1 or greater.

9. The processing apparatus (10) of any one of claims 1 to 3, wherein the at least one anode comprises platinum, titanium, niobium, lead, gold, an alloy comprising at least one of them, an oxide thereof, and / or a mixture thereof.

10. The processing apparatus (10) of any one of claims 1 to 3, wherein the at least one anode provides 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.

11. The processing apparatus (10) of claim 10, wherein A1:A2 is in the range of 5:1 to 100:

1.

12. The processing apparatus (10) of claim 10, wherein A1 is in the range of 10 dm2 / dm3 to 100 dm2 / dm3 based on the free internal volume (V).

13. The processing apparatus (10) of any one of claims 1 to 3, wherein the processing apparatus (10) and / or the at least one anode unit has at least one inner surface comprising or being made of fluorinated plastic.

14. The processing apparatus (10) of claim 1, wherein the at least one anode provides 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, the at least one anode comprises a stack of anode layers (25), and the at least one anode comprises platinum, titanium, niobium, lead, gold, an alloy comprising at least one of them, an oxide thereof, and / or a mixture thereof.

15. A method for processing manganese oxide in a processing apparatus (10) of any one of claims 1 to 14, the method comprising the steps of: (A) providing at least one manganese substance having an oxidation number lower than +7 in a liquid in the processing apparatus (10), and (B) applying an electric current to the at least one anode and the at least one cathode of the processing apparatus (10) such that at least a portion of the at least one manganese substance is anoly oxidized to a manganese substance having an oxidation number of +7.

16. The method of claim 15, wherein the liquid system is acidic.

17. The method of claim 15 or 16, wherein the liquid system is acidic and the at least one anode comprises a stack of anode layers (25).

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