A magnetic lanthanum oxychloride composite material for phosphorus removal from water and its preparation method

Abstract

This invention discloses a magnetic lanthanum oxychloride composite material (LaFeO-U) for phosphorus removal from water and its preparation method, relating to the field of water treatment technology. The invention involves thoroughly mixing lanthanum nitrate, ferric chloride, oxalic acid, and urea, and then synthesizing the magnetic lanthanum oxychloride composite material through a one-step molten salt calcination method. This material exhibits a reddish-brown color and a layered morphology with abundant phosphorus adsorption active sites, enabling efficient adsorption of both inorganic and organic phosphorus in water. Its high phosphorus adsorption capacity, fast adsorption kinetics, and magnetic recovery characteristics further expand the application range of this novel lanthanum-based phosphorus removal material. Furthermore, the preparation method is simple, convenient, and inexpensive, making it suitable for large-scale production.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, and in particular to a magnetic lanthanum oxychloride composite material for removing phosphorus from water and its preparation method. Background Technology

[0002] Total phosphorus in water bodies includes both organic and inorganic phosphorus, with phosphate being the most direct source of phosphorus nutrients for algae. Excessive phosphate levels in water can trigger rapid algal proliferation, leading to uncontrollable algal growth, mass fish and shrimp deaths, accelerated eutrophication, and a drastic deterioration of the ecological environment. Therefore, phosphorus pollution is a prominent pollution problem in key river basins, and phosphorus removal is crucial for reducing eutrophication and improving water quality.

[0003] Adsorption technology has stood out among numerous eutrophic water remediation technologies due to its simplicity, environmental friendliness, and cost advantages. The core of adsorption technology lies in the development of adsorption materials. Lanthanide materials, with their excellent phosphate adsorption and removal capabilities, are widely used in the preparation of phosphorus adsorbents. Over the past thirty years, countless institutions have invested in the development and application research of lanthanide-based phosphorus removal materials, preparing materials with La... 3+ A series of phosphorus removal composite materials with active components such as La(OH)3, La2O3 and La2O2CO3.

[0004] However, most current research focuses on the removal of inorganic phosphates from water bodies, lacking effective solutions for organic phosphorus in water. Furthermore, lanthanum-based phosphorus removal materials are mostly modified based on traditional lanthanum-based active components, lacking the development of novel lanthanum-based active components. In addition, further in-depth research is needed to improve the simultaneous removal efficiency of inorganic and organic phosphorus and the recycling and reuse of adsorbents. Summary of the Invention

[0005] This invention provides a magnetic lanthanum oxychloride composite material for removing phosphorus from water and its preparation method. The magnetic lanthanum oxychloride composite material is prepared by using lanthanum nitrate, ferric chloride, oxalic acid and urea, which can simultaneously improve the adsorption efficiency of organic and inorganic phosphorus in water, and has high phosphorus adsorption capacity and fast adsorption kinetics.

[0006] To address the aforementioned technical problems, one objective of this invention is to provide a magnetic lanthanum oxychloride composite material for removing phosphorus from water, comprising the following components in parts by weight:

[0007] Lanthanum nitrate: 2.24 parts;

[0008] Ferric chloride: 0.448 parts - 4.48 parts;

[0009] Oxalic acid: 0 parts - 2.73 parts;

[0010] Urea: 27.27-30 parts.

[0011] As a preferred embodiment, the mass ratio of oxalic acid to urea is (0.029-0.3):1.

[0012] As a preferred embodiment, the mass ratio of lanthanum nitrate to ferric chloride is 1:(0.2-2).

[0013] As a preferred embodiment, the amount of oxalic acid added is 0.87-2.73 parts by weight.

[0014] To address the aforementioned technical problems, a second objective of this invention is to provide a method for preparing a magnetic lanthanum oxychloride composite material for removing phosphorus from water, comprising the following steps: mixing and grinding lanthanum nitrate, ferric chloride, oxalic acid, and urea in a grinding medium, placing the mixture in a crucible, calcining it at a constant temperature in a muffle furnace, cooling it to room temperature, and then grinding and sieving the product to obtain the magnetic lanthanum oxychloride composite material.

[0015] By adopting the above-mentioned scheme, this application aims to develop a novel lanthanum-based material as a phosphorus adsorbent. A magnetic lanthanum oxychloride composite material is prepared by calcining lanthanum nitrate, ferric chloride, oxalic acid, and urea using a simple molten salt method. This magnetic lanthanum oxychloride composite material is reddish-brown in color and exhibits a large number of nanosheet-like aggregates on its surface, providing a relatively large adhesion area. This provides abundant adhesion sites for phosphorus adsorption, contributing to the improvement of the composite material's phosphorus adsorption capacity. This magnetic lanthanum oxychloride composite material not only has high adsorption efficiency for inorganic phosphorus in water but also exhibits high adsorption effects for different concentrations of organic phosphorus in water, such as adenosine triphosphate, sodium β-glycerophosphate, and potassium phytate, achieving the goal of simultaneous removal of organic and inorganic phosphorus from water. The addition of oxalic acid further promotes the formation of lanthanum oxychloride, thereby improving the adsorption efficiency of the magnetic lanthanum oxychloride composite material for both organic and inorganic phosphorus.

[0016] As a preferred option, the calcination temperature is 400-600℃.

[0017] As a preferred option, the calcination time is 2-5 hours.

[0018] As a preferred option, the heating rate during the calcination process is 2-10℃ / min.

[0019] To address the aforementioned technical problems, a third objective of this invention is to provide the application of the aforementioned magnetic lanthanum oxychloride composite material for removing phosphorus from water in the preparation of water phosphorus adsorbents.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. This application synthesizes a magnetic lanthanum oxychloride composite material by calcining lanthanum nitrate, ferric chloride, oxalic acid, and urea. The abundant nanosheet-like aggregates on the surface of the synthesized material provide rich attachment sites for phosphorus adsorption, exhibiting high adsorption efficiency not only for inorganic phosphorus in water but also for organic phosphorus of varying concentrations. The addition of oxalic acid promotes the synthesis of lanthanum oxychloride, further enhancing the material's adsorption efficiency for both organic and inorganic phosphorus. Because the magnetic lanthanum oxychloride composite material has a high adsorption capacity and fast adsorption rate for both organic and inorganic phosphorus in water, it can completely solve the problem of simultaneously improving phosphorus adsorption efficiency and organic phosphorus removal efficiency in current phosphate removal methods.

[0022] 2. The magnetic lanthanum oxychloride composite material in this application has magnetic properties due to the addition of ferric chloride raw material and the ferric oxide component produced after calcination. After adding the magnetic lanthanum oxychloride composite material to water for phosphorus removal, it can be recycled using the magnetic principle. After regeneration treatment, it can be reused and has recyclability.

[0023] 3. This application is the first to verify that the magnetic lanthanum oxychloride composite material can achieve efficient removal of organic / inorganic phosphorus in water. Its high phosphorus adsorption capacity and fast adsorption kinetics expand the application range of lanthanum-based materials for phosphorus removal. Moreover, the preparation method of this material is simple and convenient, the raw materials are easy to obtain, the product cost is low, it is environmentally safe and pollution-free, suitable for large-scale production, and has high economic benefits. Attached Figure Description

[0024] Figure 1 : This is a SEM image of a magnetic lanthanum oxychloride composite material for removing phosphorus from water, as described in Example 1 of this invention.

[0025] Figure 2 : Statistical charts showing the adsorption capacity of inorganic phosphorus in water by the materials prepared in Examples 1-4 and Comparative Examples 1-6 of this invention (Note: 1-Example 1; 2-Example 2; 3-Example 3; 4-Comparative Example 1; 5-Comparative Example 2; 6-Comparative Example 3; 7-Comparative Example 4; 8-Comparative Example 5; 9-Comparative Example 6; 10-Example 4);

[0026] Figure 3 : XRD images of the materials prepared in Examples 1 and 4 and Comparative Examples 2 and 5 of this invention;

[0027] Figure 4 : These are statistical charts showing the adsorption amounts of different organic phosphorus compounds in water by the materials prepared in Examples 1 and 4 and Comparative Examples 2 and 5 of this invention. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1

[0030] A magnetic lanthanum oxychloride composite material for removing phosphorus from water comprises 2.24 g lanthanum nitrate, 0.84 g ferric chloride, 2.73 g oxalic acid, and 27.27 g urea. The preparation method includes the following steps: lanthanum nitrate, ferric chloride, oxalic acid, and urea are thoroughly mixed and ground uniformly in a grinding media, placed in a 300 mL covered corundum crucible, and calcined at a constant temperature of 550 °C for 3 h in a muffle furnace. The calcination temperature is increased at a rate of 5 °C / min, and the mixture is then naturally cooled to room temperature. After grinding and sieving, the LaFeO-U composite material is obtained.

[0031] Example 2

[0032] A magnetic lanthanum oxychloride composite material for removing phosphorus from water comprises 2.24 g lanthanum nitrate, 1.296 g ferric chloride, 2.73 g oxalic acid, and 27.27 g urea. The preparation method includes the following steps: lanthanum nitrate, ferric chloride, oxalic acid, and urea are thoroughly mixed and ground uniformly in a grinding media, placed in a 300 mL covered corundum crucible, and calcined at a constant temperature of 550 °C for 3 h in a muffle furnace. The calcination temperature is increased at a rate of 5 °C / min, and the mixture is then naturally cooled to room temperature. After grinding and sieving, the LaFeO-U composite material is obtained.

[0033] Example 3

[0034] A magnetic lanthanum oxychloride composite material for removing phosphorus from water comprises 2.24 g lanthanum nitrate, 0.84 g ferric chloride, 0.87 g oxalic acid, and 29.13 g urea. The preparation method includes the following steps: lanthanum nitrate, ferric chloride, oxalic acid, and urea are thoroughly mixed and ground evenly in a grinding medium, placed in a 300 mL corundum crucible with a lid, and calcined at a constant temperature of 550 °C for 3 h in a muffle furnace. The calcination temperature is increased at a rate of 5 °C / min, and then naturally cooled to room temperature. After grinding and sieving the product, the LaFeO-U composite material is obtained.

[0035] Example 4

[0036] A magnetic lanthanum oxychloride composite material for removing phosphorus from water comprises 2.24 g lanthanum nitrate, 0.84 g ferric chloride, and 30 g urea. The preparation method includes the following steps: lanthanum nitrate, ferric chloride, and urea are thoroughly mixed and ground evenly in a grinding media, placed in a 300 mL covered corundum crucible, and calcined at a constant temperature of 550 °C for 3 h in a muffle furnace. The calcination temperature is increased at a rate of 5 °C / min, and then naturally cooled to room temperature. After grinding and sieving the product, the LaFe-U composite material is obtained.

[0037] Comparative Example 1

[0038] A material for removing phosphorus from water comprises 30g of urea. The preparation method includes the following steps: grinding the urea evenly in a grinding mill, placing it in a 300mL corundum crucible with a lid, placing it in a muffle furnace and calcining it at a constant temperature of 550℃ for 3h, with the calcination temperature increasing at a rate of 5℃ / min, and then naturally cooling it to room temperature. After grinding and sieving the product, the U material is obtained.

[0039] Comparative Example 2

[0040] A lanthanum-based composite material for removing phosphorus from water comprises 4.48 g of lanthanum nitrate and 30 g of urea. The preparation method includes the following steps: lanthanum nitrate and urea are thoroughly mixed and ground evenly in a grinding medium, placed in a 300 mL covered corundum crucible, and calcined at a constant temperature of 550 °C for 3 h in a muffle furnace. The calcination temperature is increased at a rate of 5 °C / min, and then naturally cooled to room temperature. After grinding and sieving the product, the La-U composite material is obtained.

[0041] Comparative Example 3

[0042] A magnetic composite material for removing phosphorus from water comprises 1.68g of ferric chloride and 30g of urea. The preparation method includes the following steps: ferric chloride and urea are thoroughly mixed and ground evenly in a grinding medium, placed in a 300mL corundum crucible with a lid, and calcined at a constant temperature of 550℃ for 3h in a muffle furnace. The calcination temperature is increased at a rate of 5℃ / min, and then naturally cooled to room temperature. After grinding and sieving the product, the Fe-U composite material is obtained.

[0043] Comparative Example 4

[0044] A composite material for removing phosphorus from water comprises 2.73 g oxalic acid and 27.27 g urea. The preparation method includes the following steps: oxalic acid and urea are thoroughly mixed and ground evenly in a grinding medium, placed in a 300 mL covered corundum crucible, and calcined at a constant temperature of 550 °C for 3 h in a muffle furnace. The calcination temperature is increased at a rate of 5 °C / min, and then naturally cooled to room temperature. After grinding and sieving the product, the OU composite material is obtained.

[0045] Comparative Example 5

[0046] A lanthanum-based composite material for removing phosphorus from water comprises 4.48 g lanthanum nitrate, 2.73 g oxalic acid, and 27.27 g urea. The preparation method includes the following steps: lanthanum nitrate, oxalic acid, and urea are thoroughly mixed and ground evenly in a grinding medium, placed in a 300 mL covered corundum crucible, and calcined at a constant temperature of 550 °C for 3 h in a muffle furnace. The calcination temperature is increased at a rate of 5 °C / min, and then naturally cooled to room temperature. After grinding and sieving the product, the LaO-U composite material is obtained.

[0047] Comparative Example 6

[0048] A magnetic composite material for removing phosphorus from water comprises 1.68g ferric chloride, 2.73g oxalic acid, and 27.27g urea. The preparation method includes the following steps: ferric chloride, oxalic acid, and urea are thoroughly mixed and ground evenly in a grinding medium, placed in a 300mL corundum crucible with a lid, and calcined at a constant temperature of 550℃ for 3h in a muffle furnace. The calcination temperature is increased at a rate of 5℃ / min, and then naturally cooled to room temperature. After grinding and sieving the product, the FeO-U composite material is obtained.

[0049] Performance testing

[0050] 1. The LaFeO-U composite material prepared in Example 1 was analyzed by scanning electron microscopy. The obtained SEM images are shown below. Figure 1 As shown, the surface of LaFeO-U is rougher and contains a large number of nanosheet-like aggregates, which provides abundant attachment sites for phosphorus adsorption active sites and helps to improve phosphorus adsorption capacity.

[0051] 2. The materials prepared in Examples 1-4 and Comparative Examples 1-6 were used for the adsorption and removal of inorganic phosphorus in water. 20 mg of adsorbent material was added to 50 ml of phosphate solution (concentration 50 mg P / L). The solution was shaken at 200 rpm / min for 24 hours at room temperature, and the pH value of the solution was recorded in real time at different times. The samples were analyzed using the molybdenum blue method and ultraviolet spectrophotometer. The adsorption capacity of inorganic phosphorus was as follows: Figure 2 As shown.

[0052] It can be observed that the composite materials of Examples 1-4 and Comparative Examples 2 and 5 have a high adsorption rate of inorganic phosphorus in water, with an adsorption amount of more than 57 mg / g. The other comparative examples have an extremely low adsorption rate of inorganic phosphorus in water, with an adsorption amount of less than 11 mg / g, which cannot meet the adsorption requirements of inorganic phosphorus in water.

[0053] 3. X-ray diffraction analysis was performed on the materials prepared in Examples 1 and 4 and Comparative Examples 2 and 5. The XRD images obtained from the analysis are as follows: Figure 3 As shown.

[0054] like Figure 3 The XRD patterns show that the typical representative diffraction peak of LaOCl (JCPDS card number: 08-0477) and the characteristic signal of α-Fe2O3 (JCPDS card number: 89-8104) both appear in LaFeO-U and LaFe-U. After the addition of oxalic acid, the peak intensity of LaFeO-U increases, indicating the formation of more LaOCl. This confirms the successful preparation of magnetic LaOCl composite materials via a one-step molten salt method. It further illustrates that the addition of oxalic acid and urea significantly affects the physicochemical properties of the composite material and may further influence the phosphorus adsorption effect.

[0055] 4. The materials prepared in Examples 1 and 4 and Comparative Examples 2 and 5 were used for the adsorption and removal of organophosphorus compounds in water. 20 mg of the adsorbent material was added to 50 ml of phosphorus solutions of different concentrations (2-50 mg P / L) (three different types of organophosphorus compounds were selected as models: adenosine triphosphate (ATP), sodium β-glycerophosphate (G1P), and potassium phytate). The solutions were shaken at 200 rpm / min for 24 h at room temperature, and the pH value of the solutions was recorded in real time. Microwave digestion was used to convert the organophosphorus compounds to phosphates. The samples were then analyzed using the molybdenum blue method and ultraviolet spectrophotometry. The adsorption capacity of the organophosphorus compounds was as follows: Figure 4 As shown.

[0056] It can be observed that, for example Figure 4 As shown, LaFeO-U in Example 1 exhibited the highest adsorption efficiency for phytate, ATP, and G1P-type organophosphates in water. In Comparative Example 2, the adsorption efficiency of La-U for ATP was similar to that of LaFeO-U, but the adsorption efficiencies for phytate and G1P were both low. Meanwhile, in Example 4, the adsorption efficiencies of LaFe-U for phytate, ATP, and G1P in water were all higher than those of LaO-U in Comparative Example 5, and the adsorption efficiency for phytate was higher than that of La-U, while the adsorption efficiency for G1P was comparable to that of La-U.

[0057] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention for those skilled in the art.

Claims

1. A method for preparing a magnetic lanthanum oxychloride composite material for removing phosphorus from water, characterized in that, Includes the following steps: Lanthanum nitrate, ferric chloride, oxalic acid, and urea were mixed and ground in a grinding media, wherein the weight parts of lanthanum nitrate were 2.24 parts, the weight parts of ferric chloride were 0.448-4.48 parts, the weight parts of oxalic acid were 0.87-2.73 parts, and the weight parts of urea were 27.27-30 parts. The mixture was placed in a crucible and calcined at a constant temperature in a muffle furnace. After cooling to room temperature, the product was ground and sieved to obtain a magnetic lanthanum oxychloride composite material.

2. The method for preparing a magnetic lanthanum oxychloride composite material for removing phosphorus from water as described in claim 1, characterized in that, The calcination temperature is 400-600 ℃.

3. The method for preparing a magnetic lanthanum oxychloride composite material for removing phosphorus from water as described in claim 1, characterized in that, The calcination time is 2-5 hours.

4. The method for preparing a magnetic lanthanum oxychloride composite material for removing phosphorus from water as described in claim 1, characterized in that, The heating rate during the calcination process is 2-10 ℃ / min.

5. A magnetic lanthanum oxychloride composite material for removing phosphorus from water, prepared by any one of the preparation methods of magnetic lanthanum oxychloride composite material for removing phosphorus from water as described in any one of claims 1-4.

6. The application of the magnetic lanthanum oxychloride composite material for removing phosphorus from water as described in claim 5 in the preparation of a water phosphorus adsorbent.

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