Iron-magnesium modified sepiolite composite material, preparation method thereof and application of iron-magnesium modified sepiolite composite material as phosphorus removal and algae inhibition functional material

Abstract

The invention discloses an iron-magnesium modified sepiolite composite material, a preparation method thereof and application of the iron-magnesium modified sepiolite composite material as a phosphorus removal and algae inhibition functional material, and belongs to the technical field of water pollution remediation. The iron-magnesium modified sepiolite composite material is formed by jointly loading magnesium hydroxide and iron hydroxide on sepiolite, has a good removal and purification effect and high selectivity on phosphorus in a phosphorus-polluted water body under the action of physical and chemical synergistic adsorption of inorganic phosphorus, and can achieve a very good phosphorus removal effect in a relatively short time; meanwhile, the growth of algae is inhibited through the synergistic effect of iron ions and magnesium ions, death of algae in polluted water is accelerated, the effect of purifying water is achieved, and the method has the advantages of being low in treatment cost, environmentally friendly, free of secondary pollution and the like.

Description

Technical Field

[0001] The invention relates to an iron-magnesium modified sepiolite composite material, in particular to an iron-magnesium modified sepiolite composite material composed of magnesium hydroxide and iron hydroxide active ingredients co-loaded on sepiolite, and also to a preparation method of the iron-magnesium modified sepiolite composite material, and application of the iron-magnesium modified sepiolite composite material as a phosphorus removal and algae inhibition functional material in phosphorus-polluted water body restoration, belonging to the technical field of water pollution restoration. Background Art

[0002] In recent years, due to the rapid advancement of urbanization, the amount of domestic sewage discharge has increased day by day. The concentration of pollutants such as nitrogen and phosphorus in natural waters such as rivers, lakes and ditches has far exceeded the environmental carrying capacity and self-purification capacity, thus changing the physical and chemical properties of natural waters, causing algae to multiply in large numbers and producing algal blooms. When algae and aquatic organisms die, the dissolved oxygen content in the water decreases, organic matter is not completely degraded, and some black and odor-causing substances are produced during anaerobic biodegradation, resulting in black and odorous water bodies.

[0003] Phosphorus is an important element for the growth of plants and animals, but high phosphorus content in water is an important cause of eutrophication. Eutrophication will not only cause a sharp increase in algae and algal blooms, but also cause oxygen deficiency in aquatic organisms. Eventually, the water may become black and smelly, further deteriorating the water quality. It is generally believed that when the phosphorus content in water reaches 0.02 mg / L, the water is in a eutrophic state. Therefore, how to use efficient and green methods to remove phosphorus from water is the key.

[0004] At present, algae removal is mainly divided into physical, chemical and biological methods. The physical algae removal method treats both the symptoms and the root causes, but due to its large workload and high processing cost, it is not suitable for large-scale treatment. The biological method has low cost, but the removal effect is slow and is not suitable for the treatment of algae blooms. The chemical method has good algae removal effect and fast speed, but it is easy to cause secondary pollution. The phosphorus removal technologies mainly include membrane separation, chemical crystallization, biological method and adsorption method. The membrane separation method has high efficiency, low energy consumption, and can be reused, but the filter membrane is easily damaged. The chemical crystallization method is simple to operate and has stable phosphorus removal, but it is expensive and prone to secondary pollution. The biological method is low-cost and has no secondary pollution, but its stability is poor. Adsorption is a phosphorus removal technology with the advantages of simple operation, convenient management, good treatment effect, and conducive to recycling.

[0005] In recent years, composite adsorbents based on metal (hydroxy) oxides have attracted attention. Iron, as a Lewis acidic metal, has a strong ability to bind phosphorus. At the same time, iron has high abundance in the earth's crust, low cost, and low toxicity. It is a nutrient element required by animals and plants and participates in the physiological and biochemical processes of animals and plants. Sepiolite is a fibrous magnesium-rich silicate mineral, composed of two layers of silicon-oxygen tetrahedrons sandwiching a layer of magnesium-oxygen octahedron. It has a chain-layer structure and is low in price, environmentally friendly, large specific surface area, and rich active sites. Using natural sepiolite with a large specific surface area and porous structure as a carrier to prepare iron-modified sepiolite can increase the positive charge on the surface of sepiolite, strengthen its adsorption performance for inorganic phosphorus, improve its adsorption capacity and low-concentration phosphorus removal ability, and significantly enhance the phosphorus removal adsorption performance of sepiolite. Chinese patent CN1698948A discloses a water purifier with sepiolite as a carrier and its preparation and use method, which is a water purifier with trivalent iron ions and its hydroxide attached in the mineral lattice and on the surface of sepiolite, and has a strong adsorption capacity for anionic pollutants in water bodies, such as soluble phosphorus, nitrate nitrogen and nitrite nitrogen, and phytoplankton with negative charges on the surface, and has the dual functions of inhibiting eutrophication of water bodies and killing phytoplankton, which is suitable for water purification in the aquaculture industry. Conventional use can purify water quality and prevent the occurrence of aquatic diseases. However, the patent only mentions that its water purifier has both phosphorus removal and algae inhibition functions, and does not specifically disclose its phosphorus removal and algae inhibition technical effects. Moreover, its algae removal process is mainly to adsorb phytoplankton to make the algae sink to the bottom of the sea and die, making it impossible to recycle and reuse the water purifier. At the same time, the phosphorus adsorbed by the water purifier cannot be recycled, and the use cost is high. Summary of the invention

[0006] In view of the technical defects in the phosphorus removal and algae inhibition process of water purifiers in the prior art, the first purpose of the present invention is to provide an iron-magnesium modified sepiolite composite material, which has a good removal and purification effect on phosphorus in phosphorus-contaminated water bodies through the physical and chemical synergistic adsorption of inorganic phosphorus, has high selectivity, and can achieve a good phosphorus removal effect in a relatively short time. At the same time, it inhibits the growth of algae through the synergistic effect of iron ions and magnesium ions, accelerates the death of algae in polluted water bodies, and plays a role in purifying water quality.

[0007] The second object of the present invention is to provide a method for preparing an iron-magnesium modified sepiolite composite material, which has low raw material cost, simple operation and is conducive to industrial production.

[0008] The third object of the present invention is to provide an iron-magnesium modified sepiolite composite material for use as a phosphorus removal and algae inhibition functional material in the restoration of phosphorus-polluted water bodies. The material has high removal efficiency and good effect on inorganic phosphorus, can quickly remove inorganic phosphorus, and can recycle phosphorus resources to create new value. At the same time, it has an inhibitory effect on algae in phosphorus-polluted water bodies, thereby better purifying the water quality.

[0009] In order to achieve the above technical objectives, the present invention provides an iron-magnesium modified sepiolite composite material, which is composed of magnesium hydroxide and iron hydroxide jointly loaded on sepiolite; wherein the mass ratio of magnesium hydroxide to iron hydroxide is measured according to the mass ratio of magnesium to iron of (0.1~1):1.

[0010] The iron-magnesium modified sepiolite composite material of the present invention uses natural sepiolite mineral as a carrier, and loads active magnesium hydroxide and iron hydroxide active ingredients. The sepiolite mineral has the characteristics of large specific surface area and rich active sites, and is rich in silicon, magnesium, calcium, and contains some elements such as iron and aluminum. It itself has good phosphorus removal activity. Using the sepiolite mineral as a carrier can achieve highly dispersed loading of magnesium hydroxide and iron hydroxide active ingredients, and give full play to the phosphorus removal activity of the active ingredients. Magnesium hydroxide and iron hydroxide, as active ingredients, show obvious synergistic effects on phosphorus removal and algae inhibition, and can promote the removal of phosphorus in water and inhibit the growth of algae. On the one hand, iron ions and magnesium ions form ≡O-Fe bonds and ≡O-Mg bonds by bonding with ≡OH in sepiolite, so that the active ingredients of magnesium hydroxide and iron hydroxide are generated in situ on sepiolite. The trivalent iron ions have Lewis acidity and a strong binding ability for phosphate anions. Magnesium ions, as another binding site for phosphate anions, can adsorb and enrich phosphorus through surface precipitation or electrostatic action, resulting in a decrease in the content of bioavailable phosphorus in the water, which makes it impossible for algae to absorb enough nutrients and thus inhibit their growth. On the other hand, the Fe in the iron-magnesium modified sepiolite composite material 3+ Reduced to Fe under anaerobic or water microbial action 2+ The living oxygen species produced during the iron redox process can inhibit the growth of algae. 2+ It will affect the synthesis of phycocyanin and photosynthesis-related genes, making it impossible to carry out photosynthesis normally, reducing the growth rate of algae, and at the same time, Mg 2+ It will lead to an increase in ROS active oxygen, cause cell membrane damage, and inhibit algae growth, so that through the joint action of iron ions and magnesium ions, better phosphorus removal and algae inhibition effects can be achieved. In addition, the active components of magnesium ions and iron ions in the iron-magnesium modified sepiolite composite material have relatively weak affinity for phosphate, and the phosphorus adsorbed and enriched on the iron-magnesium modified sepiolite composite material can basically be completely desorbed, achieving the purpose of phosphorus resource recovery and repeated use of modified sepiolite-based phosphorus removal and algae inhibition agents. The desorption of inorganic phosphorus can be completed using a dilute alkaline solution, and after multiple adsorption and desorption, the iron-magnesium modified sepiolite composite material still has a high phosphorus adsorption efficiency.

[0011] As a preferred solution, in the iron-magnesium modified sepiolite composite material, the mass ratio of magnesium hydroxide to iron hydroxide is measured according to the mass ratio of magnesium to iron of (0.1-0.3): 1. The phosphorus removal and algae inhibition effects of the iron-magnesium modified sepiolite composite material first increase and then decrease with the increase of the magnesium ratio, and when the mass ratio of magnesium to iron reaches 0.2: 1, the phosphorus removal and algae inhibition effects of the iron-magnesium modified sepiolite composite material reach the best.

[0012] As a preferred solution, the mass ratio of the total mass of the magnesium hydroxide and the iron hydroxide to the sepiolite is measured according to the mass ratio of the total mass of magnesium and iron to the sepiolite of (0.1 to 0.6): 1. When the total content of iron hydroxide and magnesium hydroxide is too high, the material will agglomerate and reduce the specific surface area, reducing the phosphorus adsorption efficiency. When the total content of iron hydroxide and magnesium hydroxide is too low, the adsorption active component content of the material will be low, which will also reduce the phosphorus adsorption efficiency. Therefore, the loading amount of iron hydroxide and magnesium hydroxide on the surface of sepiolite needs to be appropriate. It is further preferred that the mass ratio of the total mass of magnesium hydroxide and the iron hydroxide to the sepiolite is measured according to the mass ratio of the total mass of magnesium and iron to the sepiolite of (0.2 to 0.4): 1.

[0013] The present invention also provides a method for preparing an iron-magnesium modified sepiolite composite material, which comprises adding sepiolite to an aqueous solution containing iron ions and magnesium ions, adjusting the pH to alkaline to carry out a hydrolysis co-precipitation reaction, and after the reaction is completed, filtering, washing, drying and grinding are carried out in sequence to obtain the composite material.

[0014] As a preferred solution, the aqueous solution containing iron ions and magnesium ions has an iron ion concentration of 1.25 to 7.5 g / L and a magnesium ion concentration of 1.25 to 7.5 g / L. The iron ions are provided by soluble iron salts, such as FeCl3, Fe(NO3)3, etc., and the magnesium ions are provided by water-soluble magnesium salts, such as MgCl2, Mg(NO3)2, etc.

[0015] As a preferred solution, the concentration of the sepiolite added to the aqueous solution containing iron ions and magnesium ions is 15-25 g / L.

[0016] As a preferred solution, the sepiolite is pure natural sepiolite powder. The sepiolite is pure natural sepiolite powder that has not been purified, which is rich in silicon, magnesium, calcium, and contains some iron and aluminum. Compared with purified sepiolite minerals, it has better phosphorus removal and algae inhibition effects. Based on the concept of originating from nature and used for nature, the use of natural unpurified sepiolite powder effectively reduces the cost of use.

[0017] As a preferred solution, the pH is adjusted to 10 to 12. Under the preferred pH conditions, co-hydrolysis and precipitation of iron and magnesium can be achieved. The pH is further preferably adjusted to 11 to 11.5, and the pH adjustment solution is a 1 mol / L NaOH solution.

[0018] As a preferred solution, the hydrolysis coprecipitation reaction is carried out under the following conditions: stirring the reaction at room temperature for 2 to 12 hours, and the stirring reaction time is more preferably 3 to 5 hours.

[0019] The present invention also provides an application of an iron-magnesium modified sepiolite composite material as a phosphorus removal and algae inhibition functional material for phosphorus polluted water body restoration. The total inorganic phosphorus concentration in the phosphorus polluted water body is greater than 0.05 mg / L, and the pH is 3-9. Inorganic phosphorus includes H2PO4 - 、HPO4 2- , and PO4 3- wait.

[0020] As a preferred solution, the dosage of the iron-magnesium modified sepiolite composite material in phosphorus-contaminated water is 0.1-2.0 g / L.

[0021] The principle of the iron-magnesium modified sepiolite composite material of the present invention for repairing phosphorus-contaminated water bodies is as follows: 1) Iron ions and magnesium ions are chemically bonded with ≡OH in sepiolite to form ≡O-Fe bonds and ≡O-Mg bonds, which greatly promotes the adsorption and enrichment of phosphate ions. 2) The surface of the iron-magnesium modified sepiolite composite material is positively charged, and phosphates in the water body can also be removed by electrostatic attraction. 3) Fe(OH)3 and Mg(OH)2 loaded on the surface of the iron-magnesium modified sepiolite composite material can form FePO4, MgHPO4, Mg3(PO4)2 and other precipitates with phosphate through surface precipitation. 4) Fe in the iron-magnesium modified sepiolite composite material 3+ Reduced to Fe under anaerobic or water microbial action 2+ , which in turn mediates the production of reactive oxygen species, inhibiting the growth of algae. At the same time, the magnesium ions in the iron-magnesium modified sepiolite composite material will affect the synthesis of phycocyanin and photosynthesis-related genes, making it impossible for it to photosynthesize normally, reducing the growth rate of algae. At the same time, magnesium ions will lead to an increase in ROS reactive oxygen, causing cell membrane damage and inhibiting the growth of algae.

[0022] Compared with the prior art, the technical solution of the present invention has the following beneficial technical effects:

[0023] The iron-magnesium modified sepiolite composite material provided by the invention has simple preparation process, low price, environmental friendliness and will not cause secondary pollution to water bodies.

[0024] The iron-magnesium modified sepiolite composite material provided by the present invention is loaded with active ingredients of iron hydroxide and magnesium hydroxide on the surface of sepiolite. On the one hand, iron hydroxide and magnesium hydroxide can increase the specific surface area of ​​sepiolite, thereby exposing more phosphorus adsorption sites; on the other hand, ≡OH in sepiolite can form a bond with iron ions and magnesium ions to form ≡O-Fe bonds and ≡O-Mg bonds, thereby improving the load stability of iron hydroxide and magnesium hydroxide, and promoting the ability of phosphate adsorption and enrichment, and the phosphorus adsorption capacity is as high as 28.1 mg / g, which is more than 16 times higher than that of unmodified natural sepiolite, and the phosphorus adsorption process is less affected by pH and has strong anti-interference ability. At the same time, since the affinity of iron and magnesium to phosphate is relatively not very strong, phosphorus enriched in the modified sepiolite-based phosphorus removal and algae inhibitor is easier to desorb and recover, and the phosphorus desorption rate can reach more than 90%. Through multiple recycling, the use cost can be further reduced. In addition, the decrease in phosphorus concentration in water leads to a decrease in the content of nutrients available to algae, achieving the effect of inhibiting growth.

[0025] The Fe in the iron-magnesium modified sepiolite composite material of the present invention 3+ Reduced to Fe under anaerobic or water microbial action 2+ The reactive oxygen species produced during the redox process of iron can destroy the cell structure of algae, damage proteins and membrane lipids, etc., leading to the death of algae and effectively reducing the algae biomass in water; and the Mg in the modified sepiolite-based phosphorus removal and algae inhibitor 2+ It can directly affect the photosynthesis-related genes and the synthesis of phycocyanin in algae, making it impossible for them to carry out photosynthesis normally. 2+ It may also lead to an increase in the active oxygen content in the system and reduce the growth rate of algae, which plays an important role in maintaining the ecological balance of water. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The scanning electron microscope images of the iron-magnesium modified sepiolite composite material and the natural sepiolite prepared in Example 1; wherein a is the natural sepiolite magnified 100,000 times; b is the iron-magnesium modified sepiolite composite material magnified 35,000 times; c is the iron-magnesium modified sepiolite composite material after adsorption magnified 30,000 times; d is the EDS spectrum of the iron-magnesium modified sepiolite composite material.

[0027] Figure 2 X-ray diffraction patterns (XRD) of the iron-magnesium modified sepiolite composite material prepared in Example 1 before and after adsorption and of natural sepiolite;

[0028] Figure 3It is an X-ray photoelectron spectroscopy analysis (XPS) diagram of the iron-magnesium modified sepiolite composite material prepared in Example 1 before and after adsorption; wherein, a is the full spectrum of the iron-magnesium modified sepiolite composite material before and after adsorption; b is the phosphorus fine spectrum after adsorption of the iron-magnesium modified sepiolite composite material; c is the iron fine spectrum after adsorption of the iron-magnesium modified sepiolite composite material; d is the magnesium fine spectrum after adsorption of the iron-magnesium modified sepiolite composite material.

[0029] Figure 4 The effect of coexisting anions on the phosphorus adsorption performance of the iron-magnesium modified sepiolite prepared in Example 1.

[0030] Figure 5 The effect of pH on the phosphorus adsorption capacity of the iron-magnesium modified sepiolite composite material prepared in Example 1.

[0031] Figure 6 This is the phosphorus adsorption and recycling performance of the iron-magnesium modified sepiolite prepared in Example 1. DETAILED DESCRIPTION

[0032] The following specific embodiments are intended to further illustrate the contents of the present invention in detail in conjunction with the drawings of the specification, and the following specific embodiments do not limit the protection scope of the claims.

[0033] Example 1

[0034] (1) Select natural sepiolite from Xiangtan without any treatment (main components and contents SiO2: 58.5%, MgO: 15.31%, CaO: 14.89%, Al: 6.2%, Fe2O3: 2.73%) as raw material, grind it and pass it through a 200-mesh sieve to obtain sepiolite powder.

[0035] (2) According to the mass ratio of magnesium to iron being 0.2:1 and the total mass of magnesium and iron to sepiolite being 0.3:1, FeCl3·6H2O, MgCl2·6H2O and sepiolite were mixed to a volume of 30 mL and stirred for 30 min to obtain a mixed solution. The pH value of the mixed solution was adjusted to 11-11.5 with 1 mol / L NaOH and the stirring was continued for 4 h to obtain an iron-magnesium modified sepiolite suspension.

[0036] (3) The iron-magnesium modified sepiolite suspension in (2) is filtered, washed, dried in an oven at 60° C., and ground through a 200-mesh sieve to obtain an iron-magnesium modified sepiolite composite material.

[0037] The iron-magnesium modified sepiolite composite material prepared in Example 1 was compared with natural sepiolite. It was found that the specific surface area and zero charge point of the iron-magnesium modified sepiolite composite material prepared in Example 1 were 128.08 m 2 / g and 9.8, which are 2.5 and 1.8 times higher than those of natural sepiolite respectively.

[0038] Figure 1 Scanning electron microscope images of natural sepiolite (a), the iron-magnesium modified sepiolite composite material prepared in Example 1 (b), and the iron-magnesium modified sepiolite composite material after adsorbing phosphorus (c). It can be seen that the natural sepiolite is stacked in a fibrous shape with a relatively smooth surface. After co-precipitation modification, the iron-magnesium co-oxide is attached to the bundled fibers. After adsorbing phosphorus, the surface appears stacked, which may be due to the complex precipitation of phosphate on the surface of the composite material.

[0039] Figure 2 The X-ray diffraction (XRD) diagrams of natural sepiolite and the iron-magnesium modified sepiolite composite material prepared in Example 1 before and after adsorption show that natural sepiolite has SiO2 and CaCO3. After iron-magnesium modification, obvious Fe(OH)3 and Mg(OH)2 crystals are generated. After phosphorus adsorption, the iron-magnesium modified sepiolite composite material has obvious characteristic peaks of FePO4, Mg3(PO4)2, MgHPO4, and Mg(H2PO4)2, indicating that phosphorus is successfully loaded on the iron-magnesium modified sepiolite composite material, and stable phosphate precipitation is generated after adsorption.

[0040] Figure 3 This is the XPS graph of the iron-magnesium modified sepiolite composite material prepared in Example 1 before and after phosphorus adsorption. It can be seen that the iron-magnesium modified sepiolite composite material contains elements such as Fe and Mg before adsorption, and the iron-magnesium modified sepiolite composite material successfully loads iron and magnesium. After adsorption, the XPS absorption peak of P 2p appears. After adsorption, the binding energy position of iron and magnesium changes, which may be due to the strong interaction between phosphorus and iron and magnesium.

[0041] Figure 4 SO4 2– , Cl – 、NO3 – and CO3 2- The effect of four coexisting ions on the phosphorus adsorption performance of the iron-magnesium modified sepiolite composite material prepared in Example 1 shows that SO4 2– , Cl – and NO3 – The presence of CO3 has little effect on the adsorption of phosphorus, while 2- The presence of CO3 can reduce the adsorption of phosphorus by the ferromagnesian modified sepiolite composite to a certain extent, which may be due to 2- It forms carbonate precipitates with iron and magnesium ions, resulting in a reduction in phosphorus adsorption sites.

[0042] Figure 5The recycling of the iron-magnesium modified sepiolite composite material prepared in Example 1 is as follows: under the conditions of pH 5 and phosphorus concentration of 30 mg / L, the phosphorus concentration is measured after adsorption for 24 hours, and then the iron-magnesium modified sepiolite composite material after the reaction is collected and placed in a 1 mol / L NaOH solution for desorption for 24 hours, and the regenerated adsorbent is collected and placed in a 30 mL KH2PO4 solution with a concentration of 100 mg / L for adsorption for 24 hours, and the phosphorus concentration in the solution is measured, and this is repeated 5 times. It can be seen that after five cycles of use, the phosphorus adsorption capacity of the iron-magnesium modified sepiolite composite material has almost no obvious attenuation, and has good recyclability.

[0043] Example 2

[0044] (1) Select natural sepiolite from Xiangtan without any treatment (main components and contents SiO2: 58.5%, MgO: 15.31%, CaO: 14.89%, Al: 6.2%, Fe2O3: 2.73%) as raw material, grind it and pass it through a 200-mesh sieve to obtain sepiolite powder.

[0045] (2) According to the mass ratio of magnesium to iron being 0.1:1 and the total mass of magnesium and iron to sepiolite being 0.3:1, FeCl3·6H2O, MgCl2·6H2O and sepiolite were mixed to a volume of 30 mL and stirred for 30 min to obtain a mixed solution. The pH value of the mixed solution was adjusted to 11-11.5 with 1 mol / L NaOH and the stirring was continued for 4 h to obtain an iron-magnesium modified sepiolite suspension.

[0046] (3) The iron-magnesium modified sepiolite suspension in (2) is filtered, washed, dried in an oven at 60° C., and ground through a 200-mesh sieve to obtain an iron-magnesium modified sepiolite composite material.

[0047] Example 3

[0048] (1) Select natural sepiolite from Xiangtan without any treatment (main components and contents SiO2: 58.5%, MgO: 15.31%, CaO: 14.89%, Al: 6.2%, Fe2O3: 2.73%) as raw material, grind it and pass it through a 200-mesh sieve to obtain sepiolite powder.

[0049] (2) According to the mass ratio of magnesium to iron being 0.5:1 and the total mass of magnesium and iron to sepiolite being 0.3:1, FeCl3·6H2O, MgCl2·6H2O and sepiolite were mixed to a volume of 30 mL and stirred for 30 min to obtain a mixed solution. The pH value of the mixed solution was adjusted to 11-11.5 with 1 mol / L NaOH and the stirring was continued for 4 h to obtain an iron-magnesium modified sepiolite suspension.

[0050] (3) The iron-magnesium modified sepiolite suspension in (2) is filtered, washed, dried in an oven at 60° C., and ground through a 200-mesh sieve to obtain an iron-magnesium modified sepiolite composite material.

[0051] Example 4

[0052] 30 mg of the iron-magnesium modified sepiolite composite material prepared in Example 1 was added to multiple 50 mL centrifuge tubes respectively, and then 30 mL of a phosphate solution with a phosphorus concentration of 100 mg / L was added respectively, and the initial pH of the solution was adjusted to 3, 4, 5, 6, 7, 8, 9, 10, and 11 with 1 mol / L HCl and NaOH solutions. The tubes were placed at 25° C. and shaken at 200 rpm for 24 h. The suspension was filtered through a 0.45 μm filter membrane, and the phosphate concentration of the solution was determined by a molybdenum antimony colorimetric method.

[0053] from Figure 6 It can be seen that when the pH is between 3 and 9, the iron-magnesium modified sepiolite composite material has a higher phosphorus removal performance. When the initial pH rises to 10 or above, due to the presence of a large amount of OH in the solution - , forming a strong competition for the adsorption of phosphate on the surface of the iron-magnesium modified sepiolite composite material, resulting in a decrease in the amount of phosphorus adsorption.

[0054] Comparative Example 1

[0055] Same as Example 1, except that the sepiolite used is purified sepiolite.

[0056] Comparative Example 2

[0057] Same as Example 1, except that only the iron solution is added.

[0058] Comparative Example 3

[0059] Same as Example 1, except that only magnesium solution is added.

[0060] Example 5

[0061] The modified sepiolite composite materials prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were adsorbed for 24 hours at 25° C., 200 rpm, pH=5, and a phosphate concentration of 100 mg / L. The results are shown in Table 1.

[0062] Table 1

[0063]

[0064] Example 6

[0065] The modified sepiolite composite materials prepared in Examples 1 to 2 and Comparative Examples 1 to 3 were added to algae at an initial concentration of about 9×10 5In the simulated algal bloom water with 1 g / L cells / mL, the modified sepiolite composite material was placed in an incubator at 25°C, alternating between day and night for 24 hours, and the algae was shaken three times during the experiment. After the experiment, the algae content and chlorophyll a content in the water were measured. The results are shown in Table 2.

[0066] Table 2

[0067]

[0068]

[0069] As can be seen from Table 2, the iron-magnesium modified sepiolite composite material has a good anti-algae effect. Compared with the modification of single iron or magnesium hydroxide, the iron-magnesium co-hydroxide modified sepiolite shows a stronger anti-algae effect, indicating that there is a synergistic anti-algae effect between iron and magnesium hydroxide.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An iron-magnesium modified sepiolite composite material, characterized in that: The invention is composed of magnesium hydroxide and iron hydroxide which are jointly loaded on sepiolite; wherein the mass ratio of magnesium hydroxide to iron hydroxide is measured according to the mass ratio of magnesium to iron being (0.1-1):

1.

2. The iron-magnesium modified sepiolite composite material according to claim 1, characterized in that: The mass ratio of the total mass of the magnesium hydroxide and the iron hydroxide to the sepiolite is measured according to the mass ratio of the total mass of magnesium and iron to the sepiolite being (0.1-0.6):

1.

3. The method for preparing an iron-magnesium modified sepiolite composite material according to claim 1 or 2, characterized in that: Add sepiolite to an aqueous solution containing iron ions and magnesium ions, adjust the pH to alkaline to carry out a hydrolysis co-precipitation reaction, and after the reaction is completed, filter, wash, dry and grind in sequence to obtain the product.

4. The method for preparing an iron-magnesium modified sepiolite material according to claim 3, characterized in that: The aqueous solution containing iron ions and magnesium ions has an iron ion concentration of 1.25 to 7.5 g / L and a magnesium ion concentration of 1.25 to 7.5 g / L; The concentration of the sepiolite added to the aqueous solution of iron ions and magnesium ions is 15-25 g / L.

5. The method for preparing a magnesium-iron modified sepiolite composite material according to claim 3 or 4, characterized in that: The sepiolite is pure natural sepiolite mineral powder.

6. The method for preparing an iron-magnesium modified sepiolite composite material according to claim 3, characterized in that: The pH is adjusted to 10-12.

7. The method for preparing an iron-magnesium modified sepiolite composite material according to claim 3, characterized in that: The conditions of the hydrolysis coprecipitation reaction are: stirring the reaction at room temperature for 2 to 12 hours.

8. The use of an iron-magnesium modified sepiolite composite material according to claim 1 or 2, characterized in that: It can be used as a phosphorus removal and algae inhibition functional material for the restoration of phosphorus-polluted water bodies.

9. The use of an iron-magnesium modified sepiolite composite material according to claim 8, characterized in that: The total concentration of inorganic phosphorus in the phosphorus-polluted water body is greater than 0.05 mg / L, and the pH value is 3-9.

10. The use of an iron-magnesium modified sepiolite composite material according to claim 8 or 9, characterized in that: The dosage of the iron-magnesium modified sepiolite composite material in the phosphorus-contaminated water body is measured at 0.1-2 g / L.

Images