Polymeric ferric chloride and method for its production and use

Abstract

The present application relates to the technical field of water treatment agent, in particular to a kind of polymeric ferric chloride and its production method and application;The present application sequentially adds water, hydrochloric acid, ferrous chloride, tungsten-molybdenum co-loaded manganese-based catalyst in reaction kettle, under the state of stirring, oxygen is passed to carry out catalytic oxidation reaction until the ferrous content in system is less than 0.01wt%, after the recovery of the tungsten-molybdenum co-loaded manganese-based catalyst by solid-liquid separation, the polymeric ferric chloride in liquid state is obtained;The total loading of tungsten element and molybdenum element in the tungsten-molybdenum co-loaded manganese-based catalyst accounts for 10%-30% of mass percentage;Polymeric ferric chloride obtained by the method of the present application can be used for sewage sludge treatment, also can be used for circuit board etching, and the treatment effect is better.

Description

Technical Field

[0001] This invention relates to the field of water treatment agent technology, specifically to a polyferric chloride, its production method, and its application. Background Technology

[0002] Polyferric chloride (PFCC) is an inorganic polymer compound, typically represented by the chemical formula [Fe(OH)3]nCl3n-x·mH2O, where n represents the degree of polymerization, x represents the charge number, and m represents the amount of water of crystallization. It is formed by the hydrolysis and polymerization of ferric chloride (FeCl3) under certain conditions, exhibiting high charge density and excellent flocculation effects. PFCC is used as a flocculant in tap water treatment, industrial wastewater treatment, and sewage treatment, effectively removing suspended solids, colloidal particles, and some dissolved pollutants from water. Additionally, in industries such as pulp manufacturing, mineral processing, and food processing, PFCC is used as a filter aid, for decolorization, and for precipitating heavy metal ions. When used in water treatment, PFCC rapidly forms flocs, effectively removing suspended matter from water, and is suitable for various water quality conditions, including high-turbidity water and low-temperature, low-turbidity water. Compared to other flocculants, PFCC generally offers better cost-effectiveness.

[0003] Due to its strong corrosiveness, polyferric chloride (PFCC) faces varying degrees of limitations in many fields. Currently, the main production processes for PFCC are chlorination and catalytic oxidation. Chlorination uses chlorine gas, producing PFCC with high purity, suitable for circuit board etching and as a catalyst in organic chemicals. However, chlorine gas itself is toxic, and leaks can be extremely dangerous. Catalytic oxidation uses nitric acid or sodium nitrite as a catalyst and oxygen as the oxidant. PFCC produced by this process contains more impurities and salts due to the catalyst, making it unsuitable for circuit board etching. It is mostly used in wastewater or sludge treatment, and its stability as a water purification agent is also directly affected, significantly limiting its application areas. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a polyferric chloride, its production method, and its applications. The polyferric chloride product produced by the method of this invention is purer and can be used for both wastewater and sludge treatment, as well as for circuit board etching.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0006] This invention provides a method for producing polyferric chloride, comprising the following steps:

[0007] Water, hydrochloric acid, ferrous chloride, and tungsten-molybdenum co-supported manganese-based catalyst were added sequentially to a reactor. Under stirring, oxygen was introduced to carry out a catalytic oxidation reaction until the ferrous content in the system was less than 0.01 wt%. After solid-liquid separation and recovery of the tungsten-molybdenum co-supported manganese-based catalyst, liquid polyferric chloride was obtained.

[0008] The total mass percentage of tungsten and molybdenum elements in the tungsten-molybdenum co-supported manganese-based catalyst is 10%-30%.

[0009] Furthermore, the mass ratio of tungsten to molybdenum in the tungsten-molybdenum co-supported manganese-based catalyst is 0.3-0.5:1.

[0010] Furthermore, the method for obtaining the tungsten-molybdenum co-supported manganese-based catalyst is as follows: using manganese oxide as a matrix, tungsten and molybdenum elements are co-supported on the matrix by a co-precipitation method.

[0011] Furthermore, the specific preparation method of the tungsten-molybdenum co-supported manganese-based catalyst includes the following steps: under stirring conditions, manganese oxide matrix particles are added to a solution containing tungsten salt and molybdenum salt. After dissolving and dispersing evenly to form a mixed liquid, ammonia water is added dropwise until the pH value of the system is 9-12, so that tungsten ions and molybdenum ions co-precipitate on the manganese oxide matrix. After solid-liquid separation and drying, the calcined catalyst is obtained.

[0012] Preferably, the manganese oxide matrix is ​​selected from manganese dioxide with a particle diameter of 100 μm-3 mm; the tungsten salt is sodium tungstate; the molybdenum salt is ammonium molybdate; the mass fraction of the ammonia water is 5%-15%; and the solvent in the mixture is water.

[0013] Preferably, the mass ratio of the manganese oxide matrix, the tungsten salt, the molybdenum salt, and the solvent in the mixture is 10:0.6-2:2-5:100; the calcination temperature is 400-800℃ and the calcination time is 1-3h.

[0014] Further, the mass ratio of the hydrochloric acid, the ferrous chloride, water, and the oxygen is 10-20:25-40:6-10:5-20; the mass fraction of the hydrochloric acid is at least 25%; the ferrous ion content in the ferrous chloride is at least 20 wt%; and the amount of the tungsten-molybdenum co-supported manganese-based catalyst used, calculated based on the amount of polyferric chloride produced, is 2-4% of the total iron mass of the produced polyferric chloride.

[0015] Furthermore, the catalytic oxidation reaction takes 40-80 minutes.

[0016] Another aspect of the present invention is the polyferric chloride prepared by the above preparation method.

[0017] The final aspect of the present invention provides the application of the polyferric chloride prepared by the above preparation method in circuit board etching, wherein the polyferric chloride is used as an etching solution for circuit board etching.

[0018] Beneficial technical effects:

[0019] This invention uses a tungsten-molybdenum co-supported manganese-based catalyst, combined with oxygen as an oxidant, to catalytically oxidize and polymerize polyferric chloride using hydrochloric acid and ferrous chloride as raw materials. This invention replaces traditional sodium nitrite or nitric acid catalysts without changing the production process equipment or production efficiency, resulting in higher purity polyferric chloride. Moreover, the product can be used for sewage and sludge treatment as well as for circuit board etching, with good treatment effects. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] Unless otherwise specifically stated, the numerical values ​​set forth in these embodiments do not limit the scope of the invention. Techniques and methods known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques and methods should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0022] Experimental methods not specified in the following examples are generally performed according to national standards; if there is no corresponding national standard, they are performed according to general standard requirements or general methods.

[0023] The matrix used in the following cases is manganese dioxide particles with a particle size of 1-2 mm.

[0024] Example 1

[0025] A method for producing polyferric chloride includes the following steps:

[0026] Add 100g of water to a 1000mL beaker, then add 180g of hydrochloric acid (31% by mass) and 330g of ferrous chloride (26% by mass of ferrous ions). Add 2.15g of tungsten-molybdenum co-supported manganese-based catalyst (added at 2.5% of the total iron content of the produced polyferric chloride). Stir well and transfer to a 1L pressure-resistant reactor. Introduce 50g of oxygen and continue stirring for 80 minutes until the ferrous content in the system is less than 0.01wt%. After solid-liquid separation and recovery of the tungsten-molybdenum co-supported manganese-based catalyst, liquid polyferric chloride is obtained. The total iron content of the polyferric chloride obtained in this case is 13.1%, and the basicity is 7.5%. This product is designated as PFC-1.

[0027] In this case, the method for obtaining the tungsten-molybdenum co-supported manganese-based catalyst is as follows: Under stirring conditions, 4.54 g of ammonium molybdate and 1.24 g of sodium tungstate are dissolved in 100 mL of water, 10 g of manganese dioxide particles are added, and the mixture is stirred evenly to form a mixed solution. Then, 10% ammonia water is added dropwise until the pH of the system is 10.5, so that tungsten ions and molybdenum ions are co-precipitated on manganese dioxide. After solid-liquid separation and drying, the solution is calcined at 450℃ for 2.0 h to obtain the tungsten-molybdenum co-supported manganese-based catalyst, in which the total mass percentage of tungsten and molybdenum elements is 30 wt%, and the tungsten-molybdenum mass ratio is 0.35:1.

[0028] Example 2

[0029] A method for producing polyferric chloride includes the following steps:

[0030] Add 100g of water to a 1000mL beaker, then add 180g of hydrochloric acid (31% by mass) and 330g of ferrous chloride (26% by mass of ferrous ions). Add 2.15g of tungsten-molybdenum co-supported manganese-based catalyst (added at 2.5% of the total iron content of the produced polyferric chloride). Stir well and transfer to a 1L pressure-resistant reactor. Introduce 50g of oxygen and continue stirring for 60 minutes until the ferrous content in the system is less than 0.01wt%. After solid-liquid separation and recovery of the tungsten-molybdenum co-supported manganese-based catalyst, liquid polyferric chloride is obtained. The total iron content of the polyferric chloride obtained in this case is 13.15%, and the basicity is 7.35%. This product is designated as PFC-2.

[0031] In this case, the method for obtaining the tungsten-molybdenum co-supported manganese-based catalyst is as follows: Under stirring conditions, 3.65g of ammonium molybdate and 1.14g of sodium tungstate are dissolved in 100mL of water, 10g of manganese dioxide particles are added, and the mixture is stirred evenly to form a mixture. Then, 10% ammonia water is added dropwise until the pH of the system is 10.80, so that tungsten ions and molybdenum ions are co-precipitated on manganese dioxide. After solid-liquid separation and drying, the mixture is calcined at 500℃ for 2h to obtain the tungsten-molybdenum co-supported manganese-based catalyst, in which the total mass percentage of tungsten and molybdenum elements is 25wt%, and the mass ratio of tungsten to molybdenum is 0.4:1.

[0032] Example 3

[0033] A method for producing polyferric chloride includes the following steps:

[0034] Add 100g of water to a 1000mL beaker, then add 180g of hydrochloric acid (31% by mass) and 330g of ferrous chloride (26% by mass of ferrous ions). Add 2.15g of tungsten-molybdenum co-supported manganese-based catalyst (added at 2.5% of the total iron content of the produced polyferric chloride). Stir well and transfer to a 1L pressure-resistant reactor. Introduce 50g of oxygen and continue stirring for 70 minutes until the ferrous content in the system is less than 0.01wt%. After solid-liquid separation and recovery of the tungsten-molybdenum co-supported manganese-based catalyst, liquid polyferric chloride is obtained. The total iron content of the polyferric chloride obtained in this case is 13.08%, and the basicity is 7.23%. This product is designated as PFC-3.

[0035] In this case, the method for obtaining the tungsten-molybdenum co-supported manganese-based catalyst is as follows: Under stirring conditions, 2.82 g of ammonium molybdate and 0.99 g of sodium tungstate are dissolved in 100 mL of water, 10 g of manganese dioxide particles are added, and the mixture is stirred evenly to form a mixed solution. Then, 10% ammonia water is added dropwise until the pH of the system is 11.0, so that tungsten ions and molybdenum ions are co-precipitated on manganese dioxide. After solid-liquid separation and drying, the solution is calcined at 550℃ for 2.5 h to obtain the tungsten-molybdenum co-supported manganese-based catalyst, in which the total mass percentage of tungsten and molybdenum elements is 20 wt%, and the tungsten-molybdenum mass ratio is 0.45:1.

[0036] Comparative Example 1

[0037] Add 95g of water to a 1000mL beaker, then add 180g of hydrochloric acid (31% by mass) and 330g of ferrous chloride (26% by mass of ferrous ions), and add 5.5g of sodium nitrite as a catalyst. Stir well and transfer to a 1L pressure-resistant reactor. Continue stirring and introduce 50g of oxygen. React for 90 minutes until the ferrous content in the system is less than 0.01wt%. At this point, the total iron content of the polyferric chloride is 13.05%, and the basicity is 7.10%, which is denoted as PFC-4.

[0038] Comparative Example 2

[0039] Polyferric chloride was prepared using the method described in Example 1, except that manganese dioxide was used as a catalyst to react and obtain polyferric chloride. The polyferric chloride in this case had a total iron content of 13.02% by mass and a basicity of 6.86%, and was designated PFC-5.

[0040] Comparative Example 3

[0041] The catalyst was loaded with only tungsten, and the proportion of tungsten was the same as the total proportion of tungsten and molybdenum in Example 1. Polyferric chloride was prepared using manganese dioxide loaded with only molybdenum as a catalyst, following the method of Example 1.

[0042] The total iron content of the polyferric chloride is 13.0% by mass, and the basicity is 6.94%. The polyferric chloride prepared in this case is designated as PFC-6.

[0043] Comparative Example 4

[0044] The catalyst was loaded with only molybdenum, and the proportion of molybdenum was the same as the total proportion of tungsten and molybdenum in Example 1. Polyferric chloride was prepared using manganese dioxide loaded with only molybdenum as a catalyst, following the method of Example 1.

[0045] The total iron content of the polyferric chloride is 13.05% by mass, and the basicity is 7.0%. The polyferric chloride prepared in this case is designated as PFC-7.

[0046] The comparison of the above production processes shows that the production efficiency of the same proportion of raw materials is improved to a certain extent by using alumina-based composite catalysts supported on zirconium and cerium.

[0047] The coagulation performance of the above products was compared when they were used in water treatment. The results are shown in Table 1.

[0048] Table 1 Comparison of Coagulation Performance of Products in Each Case Study

[0049]

[0050] (Note: The raw water turbidity is 50 NTU, pH = 7.23, and water temperature is 15℃)

[0051] As shown in Table 1, the polyferric chloride prepared using the composite catalyst of this invention exhibits superior turbidity removal performance compared to samples prepared using other single (PFC-5) or single-composite catalysts (PFC-6 and PFC-7). Under the same dosage and to achieve the same residual turbidity, nearly 50% of the reagent usage can be saved.

[0052] Etching solutions of PFC-1, PFC-4, and PFC-6 with the same concentration were prepared and heated to 45°C. Magnetic stirring was used to simulate a spraying effect. A MoNb or AlNd thin film glass slide with a thickness of 300 nm was then immersed in the prepared etching solution. The film surface was observed to fade to colorless. The resistivity of the film was measured using a multimeter to determine if the etching was complete. The corresponding time was recorded, and the etching rate was calculated, as shown in Table 2.

[0053] Table 2 Comparison of performance of different etching solutions at different times

[0054]

[0055] As can be seen from Table 2, compared with samples prepared by conventional processes and samples prepared by a single composite catalyst, the PFC-1 prepared by the composite catalyst in this invention has a shorter etching time and a faster etching rate for both samples.

[0056] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for producing polymeric ferric chloride, characterized by, Includes the following steps: Water, hydrochloric acid, ferrous chloride, and tungsten-molybdenum co-supported manganese-based catalyst were added sequentially to a reactor. Under stirring, oxygen was introduced to carry out a catalytic oxidation reaction until the ferrous content in the system was less than 0.01 wt%. After solid-liquid separation and recovery of the tungsten-molybdenum co-supported manganese-based catalyst, liquid polyferric chloride was obtained. The tungsten-molybdenum co-supported manganese-based catalyst is prepared by co-precipitating tungsten and molybdenum elements onto a manganese oxide matrix using a co-precipitation method. The specific preparation method includes the following steps: under stirring conditions, manganese oxide matrix particles are added to a solution containing tungsten salt and molybdenum salt. After dissolving and dispersing evenly to form a mixed liquid, ammonia water is added dropwise until the pH value of the system is 9-12, so that tungsten ions and molybdenum ions co-precipitate on the manganese oxide matrix. After solid-liquid separation and drying, the catalyst is calcined to obtain the tungsten-molybdenum co-supported manganese-based catalyst. The manganese oxide matrix is ​​selected from manganese dioxide, with a particle diameter of 100μm-3mm; the tungsten salt is sodium tungstate; and the molybdenum salt is ammonium molybdate. The total mass percentage of tungsten and molybdenum in the tungsten-molybdenum co-supported manganese-based catalyst is 10%-30%; the mass ratio of tungsten to molybdenum in the tungsten-molybdenum co-supported manganese-based catalyst is 0.3-0.5:

1. The mass ratio of the hydrochloric acid, the ferrous chloride, water, and the oxygen is 10-20:25-40:6-10:5-20; the mass fraction of the hydrochloric acid is at least 25%; the ferrous ion content in the ferrous chloride is at least 20 wt%; and the amount of the tungsten-molybdenum co-supported manganese-based catalyst used, calculated based on the amount of polyferric chloride produced, is 2-4% of the total iron mass of the produced polyferric chloride.

2. The method for producing polyferric chloride according to claim 1, characterized in that, The ammonia solution has a mass fraction of 5%-15%; the solvent in the mixture is water.

3. The method for producing polyferric chloride according to claim 1, characterized in that, The mass ratio of the manganese oxide matrix, the tungsten salt, the molybdenum salt, and the solvent in the mixture is 10:0.6-2:2-5:100; the calcination temperature is 400-800℃, and the calcination time is 1-3h.

4. A method for producing polyferric chloride according to any one of claims 1-3, characterized in that, The catalytic oxidation reaction takes 40-80 minutes.

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