A method and application of aluminum-carbon based composite materials to remove low-valent phosphorus by simultaneous activation of molecular oxygen oxidation and flocculation

Abstract

The present invention provides a method and application for the simultaneous activation of molecular oxygen oxidation and flocculation to remove low-valent phosphorus using an aluminum-carbon-based composite material. The method comprises: placing aluminum powder, a divalent iron salt, and activated carbon pretreated by acid leaching under an inert atmosphere for ball milling to obtain an aluminum-carbon-based composite material; adding the aluminum-carbon-based composite material to wastewater containing low-valent phosphorus and reacting under aerobic conditions. After ball milling, the exposed active zero-valent aluminum can activate molecular oxygen, which synergistically produces strong oxidizing free radicals with the iron salt to oxidize low-valent phosphates into orthophosphates; at the same time, a large number of microscopic primary cells composed of zero-valent aluminum and activated carbon can form local alkalinity on the surface of the activated carbon to promote further dissolution of aluminum, generate flocs and precipitate to remove phosphates, thereby achieving simultaneous oxidation and flocculation removal of low-valent phosphates. The material source of the present invention is wide and low-cost, the material preparation method is simple, the process for removing low-valent phosphorus is efficient and simple, the investment cost is low, and it is easy to apply in engineering.

Description

Technical Field

[0001] The present invention belongs to the technical field of water pollution treatment, and specifically relates to a method for removing low-valent phosphorus by synchronously activating molecular oxygen oxidation and flocculation of an aluminum-carbon-based composite material, and also relates to the application of the above-mentioned aluminum-carbon-based composite material in treating wastewater containing low-valent phosphates. Background Art

[0002] Hypophosphite (+1) and phosphite (+3) are widely used in the chemical industry, such as flame retardant production and electroplating, as well as in agricultural pesticide and fertilizer production. The large-scale discharge of phosphorus-containing wastewater from industry and agriculture has resulted in low-valent phosphorus becoming a significant component of total phosphorus in surface waters.

[0003] Compared with orthophosphate (+5 valence), low-valent phosphate minerals have higher solubility and are difficult to remove directly through chemical precipitation. At the same time, microorganisms metabolize low-valent phosphorus poorly, and biochemical removal of low-valent phosphorus is not easy to achieve. At present, the main method is to oxidize low-valent phosphorus to pentavalent phosphorus by adding strong oxidants (such as hydrogen peroxide, ozone, etc.), and then adjust the pH of the solution to alkaline and add flocculants to achieve chemical precipitation removal of phosphorus. Monovalent phosphorus is more easily oxidized to trivalent phosphorus, but it is not easy to oxidize trivalent phosphorus to pentavalent phosphorus, and conventional oxidants are less efficient in treating low-valent phosphorus. Moreover, the process of adding oxidants, flocculants and adjusting the pH of the solution is relatively cumbersome, which increases the amount of chemical agents and treatment costs, and also poses a risk of secondary pollution.

[0004] Therefore, it is of great practical significance to develop a new technology to improve phosphorus removal effect, simplify phosphorus removal steps and reduce treatment costs. Summary of the Invention

[0005] One of the purposes of the present invention is to provide a method for removing low-valent phosphorus by simultaneously activating molecular oxygen oxidation and flocculation of aluminum-carbon based composite materials.

[0006] The second purpose of the present invention is to provide an aluminum-carbon based composite material capable of simultaneously activating molecular oxygen oxidation and flocculation to remove low-valent phosphorus for use in removing low-valent phosphates in wastewater.

[0007] The technical solution adopted by the present invention to achieve one of the objectives is to provide a method for removing low-valent phosphorus by simultaneous activation of molecular oxygen oxidation and flocculation of aluminum-carbon based composite materials, comprising the following steps:

[0008] Aluminum powder, divalent iron salt and activated carbon are placed in an inert atmosphere and ball-milled to obtain an aluminum-carbon based composite material, wherein the activated carbon is pre-treated by acid leaching;

[0009] The aluminum-carbon-based composite material is added to wastewater containing low-valent phosphorus and reacted for a certain period of time under aerobic conditions; during the reaction, hypophosphite and / or phosphite are oxidized to orthophosphate and removed in the form of flocculation precipitation.

[0010] The overall idea of ​​the method for removing low-valent phosphorus provided by the present invention is as follows:

[0011] The present invention mechanically ball-mills aluminum powder, activated carbon, and a divalent iron salt to produce an aluminum-carbon-iron salt composite material. The activated carbon undergoes acid leaching pretreatment, preserving its acidity and preventing it from releasing it into the aqueous solution. This provides a localized acidic environment for the subsequent molecular oxygen activation process. The high-speed collisions between the aluminum powder, iron salt, and ball milling beads erode the metal surface, creating dislocation defects that destroy the aluminum powder's surface passivation layer, exposing a fresh, activated aluminum surface.

[0012] As shown in formula 1-5, the oxidation flocculation of aluminum-carbon-iron salt composite material to remove low-valent phosphate mainly undergoes a two-stage reaction process:

[0013] (1) The aluminum powder exposed on the active surface after ball milling activates oxygen, which synergistically produces strong oxidizing substances with divalent iron salts, oxidizing hypophosphite (+1 valence) and phosphite (+3 valence) to orthophosphate (+5 valence);

[0014] (2) Aluminum and activated carbon form a microscopic corrosion galvanic cell. Aluminum acts as the anode and gradually dissolves and releases electrons. The carbon surface, which acts as the cathode, undergoes a hydrolysis reaction. The generated OH- will cause the pH of the carbon surface to rise, forming a local alkaline environment. This phenomenon is named the "Galvanic cathode effect." The local alkaline environment on the activated carbon surface will promote the continuous dissolution of aluminum. The generated flocs will flocculate and precipitate orthophosphate, thereby achieving the oxidation and flocculation removal of low-valent phosphates. Furthermore, aluminum and its various hydrolysis products can stabilize the solution pH. Therefore, when using this material to treat pollutants, the solution pH can be effectively adjusted, which is beneficial to the flocculation and removal of orthophosphate.

[0015] 2Al+3O2+6H + =2Al 3+ +3H2O2 (Formula 1)

[0016] Fe 2+ + H2O2 = Fe 3+ + OH + OH - (Formula 2)

[0017] H2PO2 - + 2·OH = HPO3 2- + H2O + H + (Formula 3)

[0018] HPO3 2- + 2·OH = PO4 3- + H2O + H + (Formula 4)

[0019] nAl 3+ + PO4 3- + (3n-3)OH - = Al n PO4(OH) 3n-3 (s) (Formula 5)

[0020] In the present invention, the aluminum-carbon microscopic galvanic cell effect is utilized to achieve continuous dissolution of aluminum, and divalent iron salt is coupled to activate molecular oxygen to generate strong oxidizing species (·OH, active oxygen and other free radicals).

[0021] Furthermore, the activated carbon is selected from a combination of one or more of coconut shell activated carbon, wood activated carbon, fruit shell activated carbon and coal activated carbon. Such activated carbon materials have a large specific surface area and rich functional groups.

[0022] Furthermore, the acid leaching pretreatment includes: impregnating the activated carbon with dilute acid, washing the impregnated activated carbon until the pH value of the effluent is 4.5-6, and then drying the activated carbon.

[0023] Preferably, the dilute acid comprises hydrochloric acid or sulfuric acid at a concentration of 20 to 100 mmol / L, and the immersion time is 0.5 to 2 hours. In the present invention, by acid leaching pretreatment of the activated carbon, a local acidic environment for activating molecular oxygen can be provided during application, while also reducing the amount of acid required for pH adjustment and the number of process steps.

[0024] Furthermore, the purity of the aluminum powder is 95% to 99%, and the particle size is 50 to 2000 meshes.

[0025] Furthermore, the divalent iron salt includes ferrous chloride and / or ferrous sulfate.

[0026] In the present invention, the amount of ferrous iron salt must be controlled within a certain range based on the amount of aluminum powder used. Excessive ferrous iron salt not only reduces the abrasive effect on the aluminum powder surface during ball milling, but also reduces the amount of zero-valent aluminum, the active ingredient, during wastewater treatment, even at the same dosage, thus affecting the treatment of low-valent phosphorus. Preferably, the mass ratio of aluminum powder to the iron element in the ferrous iron salt is 1:(0.1-0.5); and the mass ratio of activated carbon to aluminum powder is (1-10):1.

[0027] Furthermore, the rotation speed of the ball milling treatment is 200-500 rpm, and the time of the ball milling treatment is 1-20 hours.

[0028] Furthermore, the particle size of the ball milling beads is 6 to 20 mm, and the mass ratio of the ball milling beads to the material is (10 to 100): 1. Preferably, the particle size of the ball milling beads includes 6 mm, 10 mm, and 15 mm, and the ratio of the number of the three added is 15:5:1.

[0029] Furthermore, the gas of the inert atmosphere is one or more of nitrogen, argon or helium.

[0030] Furthermore, the amount of the aluminum-carbon-based composite material added to the wastewater is 1 to 30 g / L.

[0031] Furthermore, the reaction under aerobic conditions includes: using air as an oxygen source in an open container, and promoting the replacement of oxygen in the solution with air by oscillation or stirring. This method directly utilizes oxygen in the air, and uses oscillation or stirring to promote the continuous influx of oxygen into the wastewater to participate in the reaction. Oxygen is widely available and inexpensive. The use of air as an oxygen source in the present invention has significant advantages in terms of cost and safety compared to oxidants such as hydrogen peroxide, persulfate, and ozone.

[0032] Furthermore, for the treatment of a large amount of low-price phosphorus-containing wastewater generated in chemical production, the reaction under aerobic conditions can also be carried out by continuously blowing oxygen-containing gas (air or oxygen) into the wastewater using equipment such as pumps.

[0033] Furthermore, the low-valent phosphorus in the wastewater includes hypophosphite and / or phosphite, and the concentration of the low-valent phosphorus is 0.1 to 30 mmol / L.

[0034] Furthermore, the initial pH of the wastewater is 3 to 11. Unlike conventional advanced oxidation systems that require strong acidic conditions, the present invention can achieve oxidation and efficient removal of low-valent phosphorus under a wide pH range without the need for additional pH adjustment to strong acidity, simplifying the phosphorus removal step, reducing treatment costs, and making the treatment process more convenient and efficient.

[0035] The technical solution adopted by the present invention to achieve the second purpose is: to provide an application of the method according to one of the purposes of the present invention in treating wastewater containing low-value phosphorus.

[0036] The low-valent phosphorus in the wastewater exists in the form of hypophosphite (+1 valence) and phosphite (+3 valence).

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) The present invention provides a method for removing low-valent phosphorus by synchronously activating molecular oxygen oxidation and flocculation of an aluminum-carbon-based composite material. The activated carbon, aluminum powder, and divalent iron salt used are all industrial-grade raw materials. The materials are cheap and easy to obtain, can be used on a large scale, effectively control the cost of treating wastewater, and have no secondary pollution. The ball milling preparation method of the aluminum-carbon-iron salt composite material is carried out at room temperature and pressure. The synthesis process is simple and the reaction conditions are mild, which is suitable for industrial preparation and production. Oxygen is widely available, cheap, and easy to obtain. Compared with oxidants such as hydrogen peroxide, persulfate, and ozone, it has great advantages in cost and safety.

[0039] (2) The present invention provides a method for removing low-valent phosphorus by simultaneously activating molecular oxygen oxidation and flocculation using an aluminum-carbon-based composite material. By impregnating activated carbon with dilute acid, the acidity of the solution is not changed, which can not only provide a local acidic environment for activating molecular oxygen, but also reduce the amount of acid and process steps required for adjusting the pH. The zero-valent aluminum in the aluminum-carbon-based composite material can activate molecular oxygen, generate strong oxidizing species, and oxidize low-valent phosphates to orthophosphates. At the same time, the aluminum and the activated carbon form a primary battery to promote the continuous dissolution of aluminum. The ionization equilibrium between the dissolved aluminum and its hydrolysis products will adjust the pH of the water body. The dissolved aluminum flocs will flocculate and precipitate the oxidized orthophosphate, thereby achieving efficient and inexpensive removal of low-valent phosphates.

[0040] (3) The aluminum-carbon-based composite material provided by the present invention has high reactivity and can quickly oxidize low-valent phosphates. At the same time, the pH of the solution is adjusted by aluminum dissolution to produce flocs to remove orthophosphates, simplifying the process steps and improving the removal efficiency. The aluminum-carbon-based composite material can still maintain good metal activity and pollutant removal capabilities within a wide pH range (3 to 11) and under the interference of various ions, and can be applied to various water body remediation scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A schematic diagram of the principle of a method for removing low-valent phosphorus by simultaneous activation of molecular oxygen oxidation and flocculation of an aluminum-carbon based composite material provided by the present invention;

[0042] Figure 2 1 is a physical picture of the product obtained in Example 1 and Comparative Example 1 of the present invention;

[0043] Figure 3 In the application example 1 of the present invention, the aluminum-carbon composite material prepared in Example 1 and the activated carbon and aluminum-iron material in Comparative Example 1 were used to treat H2PO2 - Comparison of hypophosphite removal rates when simulating wastewater;

[0044] Figure 4 In the application example 1 of the present invention, the aluminum-carbon composite material prepared in Example 1 and the activated carbon and aluminum-iron material in Comparative Example 1 were used to treat H2PO2 - Comparison chart of changes in phosphite concentration when simulating wastewater;

[0045] Figure 5 In the application example 1 of the present invention, the aluminum-carbon composite material prepared in Example 1 and the activated carbon and aluminum-iron material in Comparative Example 1 were used to treat H2PO2 - Comparison chart of changes in phosphate concentration when simulating wastewater. DETAILED DESCRIPTION

[0046] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0047] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0048] The present invention will be further described below with reference to specific examples, but they are not intended to limit the present invention.

[0049] See Figure 1 The principle diagram shows this method, which utilizes aluminum powder, activated carbon, and a divalent iron salt to prepare an aluminum-carbon-iron salt composite powder by ball milling. Molecular oxygen is activated to generate strong oxidizing free radicals, rapidly oxidizing low-valent phosphorus to pentavalent phosphorus. Simultaneously, the activated aluminum continuously dissolves, forming flocs that efficiently remove pentavalent phosphate, achieving efficient oxidative flocculation and removal of low-valent phosphates.

[0050] Example 1

[0051] To four 100mL stainless steel ball mills, a total of 70g of agate beads were added. Ball milling beads with diameters of 15mm, 10mm, and 6mm were added in a ratio of 1:5:15. 2.5g of acid-pretreated coconut shell activated carbon (soaked in 30mmol / L dilute hydrochloric acid for 2h, rinsed to a pH of 5, and then dried), 0.5g of aluminum powder (80-150μm, 99% purity), and 1g of ferrous sulfate heptahydrate (99% purity) were weighed into the mills, resulting in a mass ratio of aluminum, iron, and carbon of 25:5:2, and a mass ratio of material to ball milling beads of 1:20. The sealed mills were evacuated and purged with argon as a protective gas. The mills were then placed in a planetary ball mill at 400rpm and milled continuously for 3h. After milling, the resulting aluminum-carbon composites were removed and placed under nitrogen.

[0052] Example 2

[0053] The difference between this embodiment and embodiment 1 is that 1 g of ferrous sulfate heptahydrate is replaced by 0.71 g of ferrous chloride tetrahydrate, and other conditions remain unchanged. The prepared aluminum-carbon-based composite material is placed under nitrogen protection.

[0054] Example 3

[0055] To four 100 mL stainless steel ball mills, a total of 70 g of agate beads were added. Ball milling beads with diameters of 15 mm, 10 mm, and 6 mm were added in a ratio of 1:5:15. 2.5 g of acid-pretreated wood activated carbon (using 50 mmol / L dilute hydrochloric acid for 0.5 h, rinsing to a pH of 4.5, and drying), 0.5 g of aluminum powder (80-150 μm, 99% purity), and 0.25 g of ferrous sulfate heptahydrate (99% purity) were weighed and added to the mills, resulting in a mass ratio of aluminum, iron, and carbon of 25:5:0.5, and a mass ratio of material to ball milling beads of 1:21. The sealed mills were evacuated and purged with argon as a protective gas. The mills were then placed in a planetary ball mill at 500 rpm and milled continuously for 2 h. After milling, the resulting aluminum-carbon composites were removed and placed under nitrogen.

[0056] Example 4

[0057] To four 100mL stainless steel ball mills, a total of 70g of agate beads were added. Ball milling beads with diameters of 15mm, 10mm, and 6mm were added in a ratio of 1:5:15. 2.5g of acid-pretreated activated carbon from fruit shells (pre-treated with 30mmol / L dilute sulfuric acid for 2h, rinsed to a pH of 5.5, and then dried), 0.5g of aluminum powder (80-150μm, 99% purity), and 0.75g of ferrous sulfate heptahydrate (99% purity) were weighed into the mills, resulting in a mass ratio of aluminum, iron, and carbon of 25:5:1.5, and a mass ratio of material to ball milling beads of 1:19. The sealed mills were evacuated and purged with argon as a protective gas. The mills were then placed in a planetary ball mill at 300rpm and milled continuously for 4h. After milling, the resulting aluminum-carbon composites were removed and placed under nitrogen.

[0058] Example 5

[0059] To four 100mL stainless steel ball mills, a total of 70g of agate beads were added. Ball milling beads with diameters of 15mm, 10mm, and 6mm were added in a ratio of 1:5:15. 3g of acid-pretreated coconut shell activated carbon (soaked in 60mmol / L dilute hydrochloric acid for 0.5h, rinsed to a pH of 5, and then dried), 0.5g of aluminum powder (80-150μm, 99% purity), and 1.25g of ferrous sulfate heptahydrate (99% purity) were weighed into the ball mills, resulting in a mass ratio of aluminum, iron, and carbon of 25:5:2.5, and a mass ratio of material to ball milling beads of 1:15. The sealed ball mills were evacuated and purged with argon as a protective gas. The mills were then placed in a planetary ball mill at 400rpm for 3h. The resulting aluminum-carbon composites were removed from the mills and placed under nitrogen.

[0060] Comparative Example 1

[0061] According to the technical scheme in Example 1, pure carbon material (2.5g coconut shell activated carbon) and aluminum carbon material (2.5g coconut shell activated carbon and 0.5g aluminum powder) were prepared by ball milling. The products were placed under nitrogen protection. The actual pictures are shown in the attached Figure 2 .

[0062] Comparative Example 2

[0063] The difference between this comparative example and Example 1 is that 1 g of ferrous sulfate heptahydrate is replaced by 0.2 g of iron powder, and other steps and operations remain unchanged. The prepared aluminum-carbon-based composite material is placed under nitrogen protection.

[0064] Application Example 1

[0065] Prepare multiple 100 mL portions of 1 mM H2PO2 - Simulated wastewater was placed in a serum bottle, and the initial pH of the solution was adjusted to 6.5. 5 g / L of the aluminum-carbon-iron salt composite material prepared in Examples 1-5, the carbon and aluminum-carbon material prepared in Comparative Example 1, and the aluminum-iron-carbon composite material prepared using iron powder as raw material in Comparative Example 2 were added to the serum bottle. The amount of carbon and aluminum-carbon material added in Comparative Example 1 was consistent with the mass of the components contained in the aluminum-carbon-iron salt composite material in Example 1. The serum bottle was placed open in a constant temperature water bath oscillator with the temperature set to 25°C and the speed set to 200 rpm. 1.5 mL of sample was taken regularly and filtered with a 0.22 μm polyethersulfone filter head. The concentrations of hypophosphite, phosphite, and phosphate were detected by ion chromatography.

[0066] like Figure 3-5 As shown in Figure 1, the aluminum-carbon-iron salt material prepared in Example 1 can completely remove 0.1mM H2PO2 within 100min. -A small amount of phosphite was generated at 20 minutes, then fell below the detection limit. The phosphate concentration gradually increased in the first 80 minutes and fell below the detection limit at 120 minutes. The total phosphorus removal rate reached 100%. The removal effects of the other materials were poor.

[0067] Furthermore, the test results of the composite materials prepared in Examples 1-5 and Comparative Example 2 for the removal of low-valent phosphates are shown in Table 1 below.

[0068] Table 1

[0069] Reaction time / min <![CDATA[H2PO2 - Removal rate]]> Total phosphorus removal rate Example 1 100 100％ 100％ Example 2 100 100％ 98.7％ Example 3 120 84.8％ 80.7％ Example 4 120 96.5％ 94.4％ Example 5 120 93.1％ 90.3％ Comparative Example 2 120 7.5％ 6.0％

[0070] It can be seen from Table 1 above that

[0071] The removal effect of low-valent phosphate by the aluminum-carbon-based composite material prepared with ferrous chloride as the divalent iron salt in Example 2 is basically the same as that of the ferrous sulfate used in Example 1. Under the condition of 5g / L dosage, the reaction time is 100min and the removal rate of +1P reaches 100%. Examples 3-5 adjust the proportion of iron in the aluminum-carbon-based composite material. Under the condition of 5g / L dosage, the reaction time is 120min, and the removal rates of +1P and total phosphorus are both maintained at above 80%. In addition, as the mass ratio of aluminum: iron increases from 1:0.1 to 1:0.4, the removal rates of +1P and total phosphorus gradually increase. When the mass ratio of aluminum: iron increases to 1:0.5, the removal effect decreases. In contrast, the aluminum-iron-carbon composite material prepared with iron powder as raw material in Comparative Example 2 has a poor removal effect on low-valent phosphorus. Under the condition of 5g / L dosage and 120min reaction time, it can only remove about 7.5% of +1P. This shows that the present invention uses divalent iron salt as raw material to prepare aluminum-carbon based composite materials by ball milling with carbon and aluminum, and controls the addition amount of divalent iron salt within a reasonable range, which is an important influencing factor to ensure that the aluminum-carbon based composite materials effectively remove low-valent phosphorus.

[0072] Application Example 2

[0073] Prepare 100 mL of 1 mM H2PO2 - Simulated wastewater was used, and the initial pH of the solution was adjusted to 6.5. The aluminum-carbon-iron salt composite material prepared in Example 1 was added to serum bottles at concentrations of 0.5, 1, 5, 10, and 20 g / L, respectively. The serum bottles were placed open in a constant-temperature water bath oscillator set at 25°C and 200 rpm. 1.5 mL samples were taken periodically and filtered through a 0.22-micron polyethersulfone filter. The concentrations of hypophosphite, phosphite, and phosphate were determined by ion chromatography. As shown in Table 2, the time required to remove low-valent phosphorus decreased with increasing dosage. At a dosage of 20 g / L, low-valent phosphates were completely removed within 60 minutes. However, at a dosage of 0.5 g / L, only 65.3% of hypophosphite was removed in 160 minutes.

[0074] Table 2 Effect of different dosages on the removal of low-valent phosphate

[0075]

[0076] Application Example 3

[0077] Prepare 100 mL of 1 mM H2PO2 - Simulated wastewater was prepared using 0.1M NaOH and 0.1M H₂SO₄ to adjust the initial pH to 3, 5, 9, and 11, respectively. 5g / L of the aluminum-iron-carbon composite material prepared in Example 1 was added to a serum bottle. The serum bottle was placed open in a constant-temperature water bath shaker set to 25°C and 200 rpm for 120 minutes. 1.5mL samples were periodically removed and filtered through a 0.22-μm polyethersulfone filter. The concentrations of hypophosphite, phosphite, and phosphate were determined by ion chromatography.

[0078] As shown in Table 3, the aluminum-carbon-iron salt composite material can maintain good removal effects of low-valent phosphorus and total phosphorus in a wide range of initial solution pH, both reaching more than 90%.

[0079] Table 3 Effect of different solution initial pH on low-valent phosphate removal

[0080] Initial pH of the solution 3 5 9 11 <![CDATA[H2PO2 - Removal rate]]> 95.5％ 100％ 98.6％ 90.3％ Total phosphorus removal rate 93.2％ 100％ 98.6％ 90.3％

[0081] The above are only preferred embodiments of the present invention and do not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the contents of the present invention specification should be included in the protection scope of the present invention.

Claims

1. A method for removing low-valent phosphorus by simultaneous activation of molecular oxygen oxidation and flocculation of aluminum-carbon composite materials, characterized in that: The following steps are involved: Aluminum powder, divalent iron salt and activated carbon are placed in an inert atmosphere and ball milled to obtain an aluminum-carbon based composite material, wherein the activated carbon is pretreated by acid leaching; the mass ratio of the aluminum powder to the iron element in the divalent iron salt is 1:(0.1-0.5); the mass ratio of the activated carbon to the aluminum powder is (1-10):1; The aluminum-carbon-based composite material is added to wastewater containing low-valent phosphorus and having an initial pH of 5 to 11. In an open container, air is used as an oxygen source, and the solution is vibrated or stirred to promote the replacement of oxygen in the air. The reaction is carried out for a certain period of time. During the reaction, hypophosphite and / or phosphite are oxidized to orthophosphate and removed in the form of flocculation precipitation.

2. The method according to claim 1, characterized in that The activated carbon is selected from one or more combinations of coconut shell activated carbon, wood activated carbon, fruit shell activated carbon and coal activated carbon.

3. The method according to claim 1, characterized in that The acid leaching pretreatment includes: soaking the activated carbon with dilute acid, washing the soaked activated carbon until the pH of the effluent is 4.5-6, and then drying.

4. The method according to claim 1, wherein The divalent iron salt includes ferrous chloride and / or ferrous sulfate.

5. The method according to claim 1, wherein The ball milling process is performed at a rotation speed of 200-500 rpm and for a time of 1-20 h.

6. The method according to claim 1, wherein The amount of the aluminum-carbon-based composite material added to the wastewater is 1-30 g / L.

7. Use of the method according to any one of claims 1 to 6 in treating wastewater containing low-valent phosphorus.

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