A method and device for treating pollutants in water using aluminum alloy particles

Abstract

The present invention provides a method and device for treating pollutants in water with aluminum alloy particles. The method comprises the following steps: 1) melting metal aluminum and adding a catalyst, and casting the molten alloy liquid into aluminum alloy particles; 2) adding the aluminum alloy particles into a sewage treatment device, adding sewage to react, and 3) after the reaction is complete, filtering the reaction mixture to obtain clean water, and the aluminum alloy particles that have not reacted completely are used for the next water treatment. The aluminum alloy particles used in the present invention have strong reducing ability, can continuously react with deionized water without passivation, can reduce and decompose organic waste in sewage; inorganic waste is reduced to low-valent non-toxic ions, and has a wide range of applicable pH values ​​for sewage. Aluminum hydroxide is generated during the reaction, which acts as a flocculant, adsorbing and settling suspended matter in sewage. It has a better comprehensive water treatment effect.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment, and in particular relates to a method for treating sewage with aluminum alloy particles and adopted equipment. Background Art

[0002] Zero-valent metals have strong reduction activity and can remove heavy metals, pesticides, azo dyes, nitroaromatic compounds, nitrates, perchlorates and other pollutants in water, so they have broad application prospects in water treatment. Commonly used zero-valent metals include iron, aluminum, zinc, etc. Among them, zero-valent iron is the most widely used because of its economical, low-toxicity and abundant content. However, zero-valent iron is easily passivated and loses its activity during the reduction and decontamination process.

[0003] Zero-valent aluminum is a strong reducing agent with a redox potential of E0(Al 3+ / Al) = -1.662 V, compared to zero-valent iron E0(Fe 2+ / Fe)= -0.44V has a lower reduction potential and higher reducing ability.

[0004] Murphy (Chemical removal of nitrate from groundwater. Nature, 1991, 350: 223-225.) et al. successfully reduced nitrate in aqueous solution to NH4 using zero-valent aluminum. + , confirming that zero-valent aluminum has a high electron transfer ability. Lin (Chromate reduction by zero-valent A1 metal as catalyzedby polyoxometalate. Water research, 2009, 43(20); 5015-5022) et al. used polyoxometalate to pre-treat zero-valent aluminum to reduce and degrade chromate. In this reaction process, the surface oxide layer of zero-valent aluminum was removed and it showed a strong reducing ability.

[0005] The main problem with the application of zero-valent aluminum is the presence of an oxide layer on its surface. Therefore, zero-valent aluminum must be pretreated to remove its surface oxide layer before it can exert its strong reducing ability. Summary of the invention

[0006] In order to solve the above problems of the prior art, the present invention proposes a method for treating pollutants in water using aluminum alloy particles.

[0007] Another object of the present invention is to provide a device for treating pollutants in water using aluminum alloy particles.

[0008] The technical solution for achieving the above-mentioned purpose of the present invention is:

[0009] A method for treating pollutants in water using aluminum alloy particles comprises the following steps:

[0010] 1) Melting metallic aluminum and adding a catalyst, and casting the molten alloy liquid into aluminum alloy particles; the catalyst is an alloy composed of one or more of the following low melting point metals, or a compound containing one or more of the following low melting point metals: tin, bismuth, indium, zinc, potassium, lithium and antimony, and the mass of the catalyst accounts for 0.05-1.5% of the total mass of the raw materials;

[0011] 2) adding the aluminum alloy particles into the sewage treatment equipment and adding sewage to react,

[0012] 3) After the reaction is complete, the reaction mixture is filtered to obtain clean water, and the unreacted aluminum alloy particles are used for the next water treatment.

[0013] The metal aluminum in step 1) can be one or more of aluminum ingots, recycled aluminum scraps, and aluminum scraps. Using recycled aluminum scraps and aluminum scraps can greatly reduce costs.

[0014] The catalyst is one of pure bismuth, pure indium, indium-bismuth alloy, bismuth-indium-tin-zinc alloy, bismuth-indium-tin-lead alloy, bismuth-potassium alloy and bismuth-lithium alloy.

[0015] Furthermore, in step 1), after all the metal is melted into molten alloy liquid, a vacuum metal granulator is used to form aluminum alloy particles with a particle size of 2-5 mm.

[0016] Wherein, in step 2), the mass ratio of the aluminum alloy particles to the pollutants in the sewage is 100 to 1000.

[0017] The pH value range of sewage treated by this method is relatively wide, which can be a range of pH value = 1 to 14.

[0018] This method can treat organic sewage and inorganic sewage contaminated with heavy metals. The sewage contains organic pollutants and / or inorganic pollutants; the organic pollutants include but are not limited to methyl orange, methyl blue, methylene blue, azo dyes, and nitro compounds; the inorganic pollutants include but are not limited to copper ions, chromium (VI) ions, cadmium ions, nitrates, and perchlorates.

[0019] A preferred technical solution of the present invention is that the sewage contains organic pollutants and / or inorganic pollutants; and the reaction time in step 2) is 15 to 120 minutes.

[0020] Based on the experiment of treating organic wastewater, the hydraulic retention time (HRT) in actual water treatment operation is determined, which refers to the average residence time of the wastewater to be treated in the reactor, that is, the average reaction time of the wastewater and the aluminum alloy particles in the reactor. Increasing the amount of aluminum alloy particles can complete the reaction in a shorter time.

[0021] The method also includes the operation of condensing, drying and collecting hydrogen generated by the reaction of the aluminum alloy particles with sewage.

[0022] Wherein, in step 2), the aluminum alloy particles are stirred while reacting with the sewage, and the stirring speed is 50-100 r / min.

[0023] Wherein, in step 3), the reaction mixture is discharged from the treatment equipment and filtered to obtain clean water.

[0024] The method for treating pollutants in water proposed by the present invention can use any equipment that can achieve hydraulic retention time and collect hydrogen. The following is a preferred water treatment equipment proposed in this application:

[0025] A device for treating pollutants in water with aluminum alloy particles, comprising a sealed processor, wherein the upper portion of the processor is provided with a sewage inlet, and the top cover is provided with a hydrogen outlet; a filter is placed in the processor, and aluminum alloy particles are placed on the filter; the lower half of the processor is conical, and the bottom of the cone is a water outlet.

[0026] The device for treating pollutants in water with aluminum alloy particles adopts a sealed structure and can collect generated hydrogen at the same time.

[0027] The processor is filled with hydrogen, which also ensures that the aluminum alloy particles are not exposed to oxidizing gases.

[0028] Wherein, the mesh size of the filter is 0.5-1 mm; and / or

[0029] The water outlet is connected with a filter press through a pipeline.

[0030] The beneficial effects of the present invention are:

[0031] The sewage treatment method proposed by the present invention has a simple process, the aluminum alloy particles do not need to remove the subsequent oxide layer, have strong reducing ability, can continuously react with deionized water without passivation, can treat sewage with a neutral pH value, and do not need to add other chemicals.

[0032] Therefore, the requirements for sewage treatment equipment are reduced, thereby reducing the cost of sewage treatment.

[0033] The aluminum alloy particles used in the present invention can reduce and decompose organic waste in sewage; reduce inorganic waste to low-valent non-toxic ions, and have a wide range of application for the pH value of sewage. The reaction also generates aluminum hydroxide, which acts as a flocculant, adsorbs and settles suspended matter in sewage, and thus has a better comprehensive water treatment effect.

[0034] The aluminum alloy particles in this method are 2 to 5 mm in size, and there is no risk of explosion of micron-sized metal powders (especially aluminum powders), which is safe and reliable. The sewage treatment device is simple and effective in design, can be continuously treated, and has high working efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a simplified structural diagram of the equipment for treating pollutants in water using aluminum alloy particles according to the present invention.

[0036] Figure 2 A top view of the filter.

[0037] In the figure, 1 is a processor, 2 is aluminum alloy particles, 3 is a filter screen, 4 is a water outlet, 5 is a sewage inlet, 6 is a hydrogen outlet, and 7 is a filter press. DETAILED DESCRIPTION

[0038] Unless otherwise defined, all scientific and technical terms used in the present invention have the same meanings as commonly understood by one of ordinary skill in the art to which the present invention relates.

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] Unless otherwise specified, the technical means used in the present invention are all existing technical means in the art.

[0041] Example 1

[0042] 1) Melting the aluminum ingot and adding a catalyst, wherein the catalyst is an indium-bismuth alloy (the mass ratio of indium to bismuth is 2:1), and the mass of the catalyst accounts for 0.1% of the total mass of the raw materials; after all the metals are melted into molten alloy liquid, a vacuum metal granulator is used to granulate the aluminum ingot;

[0043] The molten alloy liquid is cast into aluminum alloy particles with a particle size of 2-5 mm;

[0044] 2) adding the aluminum alloy particles into a sewage treatment plant, adding sewage with a neutral pH value (pH 7) to react, sampling and monitoring the change of pollutant concentration during the reaction process until all pollutants are removed;

[0045] 3) After the reaction is complete, the reaction mixture is removed from the processor and filtered to obtain clean water.

[0046] In this example, simulated sewage was prepared with methyl orange and a water treatment test was conducted to obtain suitable water treatment conditions.

[0047] Weigh 0.5 g of aluminum alloy particles with a particle size of 5 mm and put them into 100 mL of water with a methyl orange concentration of 10 mg / L. The water temperature is 25°C and the stirring speed is 50 r / min. The pollutant concentration is detected by colorimetry and the fading time of methyl orange is recorded. The time for complete fading is 50 min.

[0048] Example 2

[0049] The aluminum alloy particles with a particle size of 2-5 mm are prepared in the same manner as in Example 1.

[0050] Weigh 0.5 g of aluminum alloy particles with a particle size of 2 mm and put them into 100 mL of water with a methyl orange concentration of 10 mg / L. The water temperature is 25°C and the stirring speed is 50 r / min. The pollutant concentration is detected by colorimetry and the fading time of methyl orange is recorded. The time for complete fading is 20 min.

[0051] The use of aluminum alloy particles with small particle size and larger specific surface area can significantly improve the efficiency of water treatment.

[0052] Example 3

[0053] The aluminum alloy particles with a particle size of 2-5 mm are prepared in the same manner as in Example 1.

[0054] 10g of aluminum alloy particles with a particle size of 2mm were put into 500ml of wastewater prepared with copper sulfate and having a copper ion content of 100mg / L. The water temperature was 25℃ and the stirring speed was 50r / min. After 30min, the copper ion content reached undetectable level, achieving effective removal of copper ions.

[0055] Example 4 Equipment for treating pollutants in water using aluminum alloy particles

[0056] This embodiment provides a device for treating pollutants in water using aluminum alloy particles. Figure 1 , comprising a sealed processor 1, a sewage inlet 5 is arranged on the upper part of the processor, a hydrogen outlet 6 and an aluminum alloy particle adding hole are opened on the top cover. A filter screen 3 is placed in the processor, and aluminum alloy particles 2 are placed on the filter screen; the lower half of the processor is conical, and the bottom of the cone is a water outlet 4. A stirring device is arranged in the processor (above the filter screen).

[0057] See also Figure 2 , the mesh size of the filter 3 is 1 mm;

[0058] The water outlet is connected to a filter press 7 via a pipeline. In this embodiment, the filter press is a plate and frame filter press.

[0059] The processor is made of stainless steel.

[0060] Example 5

[0061] Using the equipment of Example 4, a method for treating pollutants in water using aluminum alloy particles comprises the steps of:

[0062] 1) melting aluminum scraps and adding a catalyst, wherein the catalyst is an indium-bismuth alloy (the mass ratio of indium to bismuth is 2:1), and the mass of the catalyst accounts for 0.1% of the total mass of the raw materials; after all the metals are melted into molten alloy liquid, a vacuum metal granulator is used to cast the molten alloy liquid into aluminum alloy particles with a particle size of 2 to 5 mm;

[0063] 2) Aluminum alloy particles with a particle size of 2 mm were added to the device of Example 4, and sewage with a neutral pH value (pH 7) was added for reaction, and the organic pollutant content in the sewage was 100 mg / L; the mass ratio of aluminum alloy particles to organic pollutants was 500:1, the hydraulic retention time was 20 min, and a stirrer was used during the reaction at a stirring speed of 50 r / min. The aluminum alloy particles reacted with organic matter and inorganic matter in the sewage and simultaneously generated aluminum hydroxide, which acted as a flocculant, adsorbed the suspended solids (SS) and then settled.

[0064] 3) After the reaction is complete, the reaction mixture is discharged from the treatment equipment and filtered to obtain clean water.

[0065] Follow the same steps from 1) to 3) to continuously treat the sewage.

[0066] Example 6

[0067] Using the equipment of Example 4, a method for treating pollutants in water using aluminum alloy particles comprises the steps of:

[0068] 1) melting aluminum scraps and adding a catalyst, wherein the catalyst is an indium-bismuth alloy (the mass ratio of indium to bismuth is 2:1), and the mass of the catalyst accounts for 0.1% of the total mass of the raw materials; after all the metals are melted into molten alloy liquid, a vacuum metal granulator is used to cast the molten alloy liquid into aluminum alloy particles with a particle size of 2-5 mm;

[0069] 2) Aluminum alloy particles with a particle size of 2 mm were added to the equipment of Example 4, and sewage with a neutral pH value (pH 7) was added for reaction, and the organic pollutant content of the sewage was 200 mg / L; the mass ratio of aluminum alloy particles to organic pollutants was 600:1, the hydraulic retention time was 20 min, and a stirrer was used during the reaction at a stirring speed of 50 r / min. The aluminum alloy particles reacted with impurities in the sewage and simultaneously generated aluminum hydroxide, which acted as a flocculant, adsorbed the suspended solids (SS) and then settled.

[0070] 3) After the reaction is complete, the reaction mixture is discharged from the treatment equipment and filtered to obtain clean water.

[0071] Follow the same steps from 1) to 3) to continuously treat the sewage.

[0072] Although the present invention has been described above through embodiments, those skilled in the art should understand that without departing from the spirit and essence of the present invention, any improvements, substitutions and modifications made to the present invention should all fall within the scope of protection of the present invention.

Claims

1. A method for treating pollutants in water using aluminum alloy particles, characterized in that: The device used in the method comprises a sealed processor (1), the upper part of which is provided with a sewage inlet (5), the top cover of which is provided with a hydrogen outlet (6) and an aluminum alloy particle feeding hole; a filter screen (3) is placed in the processor, and aluminum alloy particles (2) are placed on the filter screen; the lower half of the processor is conical, the bottom of the cone is a water outlet (4), and an agitator is arranged above the filter screen in the processor; the mesh size of the filter screen (3) is 1 mm; the water outlet is connected to a filter press (7) via a pipeline, and the filter press is a plate and frame filter press; the material of the processor is stainless steel; The method for treating pollutants in water with aluminum alloy particles comprises the following steps: 1) melting aluminum scraps and adding a catalyst, wherein the catalyst is an indium-bismuth alloy, the mass ratio of indium to bismuth is 2:1, and the mass of the catalyst accounts for 0.1% of the total mass of the raw materials; after all the metals are melted into molten alloy liquid, using a vacuum metal granulator to cast the molten alloy liquid into aluminum alloy particles with a particle size of 2-5 mm; 2) adding aluminum alloy particles with a particle size of 2 mm to the device, adding sewage with a pH value of 7 for reaction, wherein the content of organic pollutants in the sewage is 200 mg / L; the mass ratio of aluminum alloy particles to organic pollutants is 600:1, the hydraulic retention time is 20 min, and stirring is performed with a stirrer at a speed of 50 r / min during the reaction; the aluminum alloy particles react with impurities in the sewage and simultaneously generate aluminum hydroxide, which acts as a flocculant, adsorbs the suspended matter and then settles it; 3) After the reaction is complete, the reaction mixture is discharged from the treatment equipment and filtered to obtain clean water.

Images