A magnetic adsorbent for efficiently removing heavy metals from water, and its preparation method and application

Abstract

The present invention discloses a magnetic adsorbent for efficiently removing heavy metals from water bodies, and its preparation method and application. The present invention adds shell powder to a mixed solution of a trivalent iron salt and a divalent iron salt, adds alkali to adjust the pH to 9-11, stirs the reaction, then heats the reaction, washes, and magnetically separates to obtain a magnetic substance. At least one of the trivalent iron salt and the divalent iron salt is citrate. The magnetic substance is subjected to high-temperature treatment in an oxidizing atmosphere to obtain a magnetic adsorbent for efficiently removing heavy metals from water bodies. The temperature of the high-temperature treatment is 400-800°C. The preparation method of the present invention is simple and the material cost is low. The prepared magnetic adsorbent can quickly and efficiently remove heavy metals, has a high adsorption capacity, is easy to separate and recover, and has a high initial Cd content. 2+ When the concentration was 400 mg / L, the adsorption capacity of the apple snail and clam shell adsorbents could reach 177.4 and 150.5 mg / g respectively.

Description

Technical Field

[0001] The present invention relates to the technical field of remediation of heavy metal pollution in water bodies, and in particular to a magnetic adsorbent for efficiently removing heavy metals from water bodies, and a preparation method and application thereof. Background Art

[0002] Heavy metals are non-degradable in the environment and are carcinogenic, teratogenic, and highly toxic. They accumulate in the body through the food chain, causing serious consequences such as nerve damage, organ disease, and failure. Therefore, the control of heavy metal pollution is essential.

[0003] Currently, the main technologies used for heavy metal remediation in water bodies in my country include chemical precipitation, electrolysis, membrane separation, bioremediation, and adsorption. Adsorption exploits the rich pore structure and specialized functional groups of adsorbents to adsorb heavy metals. This method boasts high efficiency, adaptability, low cost, and environmental friendliness. Commonly used adsorbents include clay minerals, activated carbon, activated alumina, and biochar. However, these adsorbents suffer from low heavy metal removal efficiency, high cost, and difficulty in separation and recovery, making them unsuitable for large-scale use. Therefore, there is an urgent need to find heavy metal adsorbents that offer high removal efficiency, low cost, and easy separation. Magnetic materials can meet the requirements for adsorbent separation and recovery. Three main methods for preparing magnetic materials are precipitation, impregnation, and liquid-phase reduction. Precipitation is widely used due to its simple preparation process and ease of operation. However, the adsorption and removal performance of magnetic materials prepared by this method is poor. Therefore, improvements are needed to enhance the removal efficiency of magnetic materials and thus improve the efficiency of heavy metal remediation in water bodies.

[0004] In recent years, due to the high consumption of seafood, a massive accumulation of shell waste has occurred, accounting for over 60% of the total seafood mass. The golden apple snail, one of the world's 100 most invasive alien species, invaded China in the 1980s, causing severe damage to rice production. As people used various methods to eradicate the snails, large quantities of shells were left as waste in the fields. The organic matter in these shell wastes oxidizes and decays in the air, exacerbating environmental pollution. These shell wastes are a type of calcified material, primarily calcium carbonate, which can account for over 95% of the total mass. This is an abundant, naturally occurring mineral that is inexpensive and highly valuable. Using shell waste to remove heavy metals from water bodies not only offers new avenues for the resourceful utilization of shells but also facilitates the remediation of heavy metal pollution. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a magnetic adsorbent for efficiently removing heavy metals from water bodies, and its preparation method and application, which has low cost and good heavy metal adsorption and removal effect.

[0006] The raw materials of the magnetic adsorbent are clam and apple snail shells, which are abundant, low-priced, and easy to obtain.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A method for preparing a magnetic adsorbent for efficiently removing heavy metals from water comprises the following steps:

[0009] (1) adding shell powder to a mixed solution of a ferric salt and a ferrous salt, adding alkali to adjust the pH to 9-11, stirring for reaction, then heating for reaction, washing, and magnetic separation to obtain a magnetic substance; at least one of the ferric salt and the ferrous salt is citrate;

[0010] (2) The magnetic material obtained in step (1) is subjected to high-temperature treatment in an oxidizing atmosphere to obtain a magnetic adsorbent that is efficient in removing heavy metals from water; the temperature of the high-temperature treatment is 400 to 800°C.

[0011] Preferably, the shell powder in step (1) is at least one of clam powder and apple snail shell powder;

[0012] Preferably, the shell powder in step (1) is shell powder obtained by passing through an 80-200 mesh sieve.

[0013] Preferably, the molar ratio of the trivalent iron in the trivalent iron salt to the divalent iron in the divalent iron salt in step (1) is 1:1 to 3:1;

[0014] Preferably, the ferric salt and the ferrous salt in step (1) are ferric citrate and ferrous sulfate, respectively.

[0015] Preferably, the solvent of the mixed solution of the ferric salt and the ferrous salt in step (1) is water;

[0016] Preferably, the concentration of the ferric salt in the mixed solution of the ferric salt and the ferrous salt in step (1) is 23.0 to 69.1 g / L.

[0017] Preferably, the pH adjustment in step (1) is to adjust the pH to 10; and the base is aqueous ammonia.

[0018] More preferably, the concentration of the ammonia water is 25%-28%.

[0019] Preferably, the base in step (1) is added to the mixed solution under stirring.

[0020] Preferably, the stirring reaction time in step (1) is 20 to 40 minutes;

[0021] Preferably, the stirring reaction temperature in step (1) is room temperature (20-30°C);

[0022] Preferably, the temperature of the heating reaction in step (1) is 100-130° C., and the time is 12-36 hours.

[0023] Preferably, after the heating reaction in step (1), the solution is evaporated to dryness;

[0024] Preferably, the oxidizing atmosphere in step (2) is oxygen or air;

[0025] Preferably, the temperature of the high temperature treatment in step (2) is 600° C.; the time of the high temperature treatment is 1 to 5 hours; and the heating rate is 200 to 800° C. / h.

[0026] The magnetic adsorbent prepared by the above preparation method can efficiently remove heavy metals in water.

[0027] The above-mentioned magnetic adsorbent for efficiently removing heavy metals in water bodies is used in water bodies polluted by heavy metals.

[0028] Preferably, the heavy metal is Cd 2+ 、Zn 2+ 、Cu 2+ and Pb 2+ At least one of .

[0029] The present invention has the following advantages and effects compared to the prior art:

[0030] (1) The adsorption material of the present invention has a simple preparation process, low cost, and is easy to separate and recover after adsorption. It also provides a new way to recycle the clam and apple snail shells. The main performance is that the preparation process is simple to operate, the raw materials are cheap, and they are easy to separate and recover after adsorption.

[0031] (2) Adsorbents A and B prepared by the present invention for Cd 2+ The adsorption capacity was 99.8 and 99.9 mg / g (pH=6, 100 mg / L*20 mL / 0.02 g). Adsorbents A and B were significantly better than the control materials, which showed that the improved material preparation method had a better effect and could greatly improve the adsorption capacity of magnetic materials for heavy metals.

[0032] (3) The adsorbent of the present invention can quickly adsorb heavy metals. Specifically, in the initial Cd 2+ When the concentration was 200 mg / L, the adsorbents approached adsorption equilibrium within 120 min of reaction time.

[0033] (4) The adsorption material of the present invention can effectively remove heavy metals in water. 2+Under the conditions of concentration, the removal rate of heavy metals can reach almost 100%. 2+ When the concentration is as high as 400 mg / L, the maximum adsorption capacity of the apple snail and clam shell adsorption materials can reach 177.4 and 150.5 mg / g respectively. In addition, the adsorption material of the present invention can also effectively remove a variety of heavy metals in water. 2+ 、Cu 2+ and Pb 2+ When the initial concentrations were 20, 50 and 100 mg / L, the removal rates of the three heavy metals were almost 100%. At a concentration of 200 mg / L, the removal rates of the clam shell and apple snail adsorption materials for Pb 2+ The adsorption capacities were 194.7 and 199.7 mg / g, respectively, and the removal rates were close to 100%.

[0034] (5) The present invention has the advantages of simple adsorbent preparation process, low material cost, rapid and efficient removal of heavy metals, and easy separation and recovery, and has broad application prospects in the treatment of heavy metal-contaminated water bodies. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a physical schematic diagram of the preparation method of Example 1 of the present invention.

[0036] Figure 2 This is a physical picture of magnetic adsorbents A and B prepared in Example 1 of the present invention.

[0037] Figure 3 1 is a hysteresis curve diagram of magnetic adsorbents A and B prepared in Example 1 of the present invention.

[0038] Figure 4 The magnetic adsorbents A and B prepared in Example 1 of the present invention are the adsorbents of Cd in water at different pH values. 2+ Effect diagram of adsorption.

[0039] Figure 5 The magnetic adsorbents A and B prepared in Example 1 of the present invention and the control material are used to measure the Cd content in water. 2+ Comparison chart of adsorption capacity.

[0040] Figure 6 The magnetic adsorbents A and B prepared in Example 1 of the present invention have different initial Cd 2+ Effect of concentration on adsorption at different temperatures.

[0041] Figure 7 This is a diagram showing the effect of different times on the adsorption effect of magnetic adsorbents A and B prepared in Example 1 of the present invention.

[0042] Figure 8 This is a diagram showing the adsorption effects of magnetic adsorbents A and B prepared in Example 1 of the present invention on other heavy metals. DETAILED DESCRIPTION

[0043] The present invention will be described in further detail below with reference to the examples and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0044] The physical schematic diagram of the preparation method of the present invention is as follows Figure 1 shown.

[0045] The preparation method of the magnetic adsorbent for efficiently removing heavy metals from water bodies of the present invention comprises the following steps:

[0046] (1) collecting clam and apple snail shells for drying and crushing;

[0047] (2) The dried clams and golden apple snail shells were treated by an improved co-precipitation method;

[0048] (3) Using a muffle furnace, the above-obtained material is subjected to high-temperature treatment under the condition of introducing oxygen, and the product is extracted to obtain a magnetic material, that is, a magnetic adsorption material for removing heavy metals.

[0049] The drying temperature in step (1) is set to 90-120° C. for 12-48 hours, and the product is sieved through a 100-mesh sieve after being crushed.

[0050] Preferably, the temperature is set to 105° C. and the time is 24 hours.

[0051] The improved coprecipitation method described in step (2) is specifically configured as follows: ferric citrate and ferrous sulfate are dissolved in pure water at a molar ratio of 1:1 to 3:1, the clams and apple snail shells sieved in step (1) are added to the solution, ammonia water is added to the solution while stirring until the pH of the solution reaches 9 to 11; stirring and reacting for a period of time. The above solution is placed in an oven (100 to 130° C., 12 to 36 hours) for heating reaction (the aqueous solution will completely evaporate), and then the material is washed with pure water multiple times, and the magnetic material is obtained through magnetic separation.

[0052] Preferably, the ferric citrate and ferrous sulfate are dissolved in pure water at a molar ratio of 2:1, and ammonia water is added until the pH of the solution reaches 10.

[0053] Preferably, the stirring reaction is continued for 30 minutes; the heating reaction is carried out at a temperature of 120° C. for 24 hours.

[0054] The high temperature treatment described in step (3) is set as follows: the material obtained in step (2) is placed in a muffle furnace, oxygen is first introduced, the temperature is raised to 400-800°C at a heating rate of 200-800°C / h, the high temperature treatment time is 1-5h, and the material is cooled to room temperature before being taken out.

[0055] Preferably, the high temperature treatment is specifically configured as follows: first introducing oxygen, heating to 600°C at a heating rate of 600°C / h, maintaining a constant temperature treatment time of 2h, cooling to room temperature and then taking out.

[0056] The room temperature and normal temperature described in the following examples are 25°C.

[0057] Example 1

[0058] Preparation of magnetic adsorbent

[0059] The collected raw materials of clam and golden apple snail shell were placed in an oven (105℃, 48h) for drying, then crushed and passed through a 100-mesh sieve. 1.2g of sieved clam and golden apple snail shell were added to 100mL of a mixed solution of ferric citrate (FeC6H5O7) and ferrous sulfate (FeSO4·7H2O) respectively. 3+ and Fe 2+ The molar ratio is 2:1, and the concentrations are 46.1g / L and 26.2g / L, respectively. 25%-28% ammonia water is added dropwise while stirring until the solution pH reaches 10, and the stirring reaction is continued for 30 minutes. The above solution is placed in an oven (120°C, 24 hours) for heating reaction (the aqueous solution will completely evaporate), and then the material is washed with pure water multiple times, and a magnetic substance is obtained through magnetic separation. The above magnetic substance is placed in a muffle furnace (pre-vented with oxygen) and heated to 600°C at a heating rate of 600°C / h. Then, it is treated at high temperature for 2 hours, cooled to room temperature, and then taken out to obtain a magnetic adsorption material. The magnetic adsorption materials of clam and apple snail shell are respectively referred to as adsorbent A and adsorbent B.

[0060] At the same time, control materials 1-9 were set up. (1) The preparation method of control materials 1 and 6 was the traditional precipitation method, specifically: 1.2 g of sieved clam and golden apple snail shells were added to 100 mL of a mixed solution of ferric sulfate (Fe2(SO4)3) and ferrous sulfate (FeSO4·7H2O) respectively. 3+ and Fe 2+The molar ratio is 2:1, and the concentrations are 36.4 g / L and 26.2 g / L, respectively. 25%-28% ammonia water is added dropwise while stirring until the pH of the solution reaches 10, and the stirring reaction is continued for 30 minutes. The above solution was placed in an oven (120°C, 24h) for heating reaction (the aqueous solution will be completely evaporated), and then the material was washed with pure water several times. After magnetic separation, the control group magnetic material was obtained. The clam and apple snail shell control materials were respectively referred to as control material 1 and control material 6; (2) The preparation process of control materials 2 and 7 was as follows: the control materials 1 and 6 obtained above were placed in a muffle furnace (oxygen was pre-introduced), and heated to 600°C at a heating rate of 600°C / h, and then high-temperature treated for 2h, cooled to room temperature and then taken out to obtain control materials. The clam and apple snail shell control materials were respectively referred to as control material 2 and control material 7; (3) The preparation process of control materials 3 and 8 was as follows: 1.2g of sieved clam and apple snail shell were added to 100mL of a mixed solution of ferric citrate (FeC6H5O7) and ferrous sulfate (FeSO4·7H2O) (FeSO4·7H2O) 3+ and Fe 2+ The molar ratio is 2:1, and the concentrations are 46.1 g / L and 26.2 g / L, respectively. 25%-28% ammonia water is added dropwise while stirring until the pH of the solution reaches 10, and the stirring reaction is continued for 30 minutes. The above solution was placed in an oven (120°C, 24h) for heating reaction (the aqueous solution will be completely evaporated), and then the material was washed with pure water for multiple times. After magnetic separation, the magnetic substance was obtained to obtain the control material. The control materials of clam and apple snail shell were respectively referred to as control material 3 and control material 8; (4) The preparation process of control material 4 and material 9 was as follows: the sieved clam and apple snail shell were placed in a muffle furnace (oxygen was introduced in advance), and heated to 600°C at a heating rate of 600°C / h, and then high-temperature treated for 2h, cooled to room temperature and taken out to obtain the control material. The control materials of clam and apple snail shell were respectively referred to as control material 4 and control material 9; (5) The preparation process of control material 5 was as follows: a mixed solution of ferric citrate (FeC6H5O7) and ferrous sulfate (FeSO4·7H2O) (Fe 3+ and Fe 2+ The molar ratio is 2:1, and the concentrations are 46.1 g / L and 26.2 g / L, respectively), and then ammonia water is added to the solution until the pH value is 10, and the above solution is placed in an oven (120°C, 24h) for reaction, and then the material is washed with pure water multiple times, and a magnetic substance is obtained by magnetic separation. The above-obtained substance is placed in a muffle furnace (oxygen is pre-introduced), and the temperature is increased to 600°C at a heating rate of 600°C / h, and then high-temperature treatment is carried out for 2h, and then cooled to room temperature and taken out to obtain control material 5.

[0061] Example 2

[0062] Physical picture of magnetic adsorbent

[0063] Figure 2The following are actual pictures of magnetic adsorbents A and B. It can be seen that there is a significant difference in color between the two materials. Adsorbent A is brick red, and adsorbent B is brown red.

[0064] Example 3

[0065] Hysteresis curve of magnetic adsorbent

[0066] The magnetic adsorbents A and B were placed in an oven (105° C., 24 h) for drying, and then the magnetic properties of the magnetic adsorbents were analyzed using a vibrating sample magnetometer to obtain the hysteresis curves of the materials.

[0067] Depend on Figure 3 It can be seen that the saturation magnetization intensities of the clam and apple snail magnetic adsorbents are 5.47emu / g and 6.63emu / g respectively. The magnetism of the two materials is sufficient to separate them from the water body after adsorption.

[0068] Example 4

[0069] Effects of different pH on Cd in water 2+ Effect of adsorption

[0070] Accurately weigh 0.02 g of two magnetic adsorbents (adsorbent A and adsorbent B prepared in Example 1) and add Cd to the mixture at different pH values (1, 2, 3, 4, 5, 6, 7). 2+ In 20 mL of a 100 mg / L solution, an oscillation adsorption test was performed at room temperature and 150 r / min for 12 h. The material was magnetically separated and the Cd content in the solution was determined using an atomic absorption spectrophotometer. 2+ concentration, and calculate Cd at different pH 2+ adsorption amount.

[0071] Depend on Figure 4 It can be seen that when the pH is 1-2, the two adsorption materials have a strong affinity for Cd 2+ The adsorption capacity of the two materials was low and did not change significantly. When the pH increased from 2 to 4, the adsorption capacity of the two materials increased rapidly and tended to equilibrium in the pH range of 4 to 6. The maximum adsorption capacity of adsorbent A was 99.8 mg / g, and the maximum adsorption capacity of adsorbent B was 99.7 mg / g. The two adsorbents had a strong affinity for Cd 2+ The removal rate is greater than 99.5%, almost reaching 100%.

[0072] Example 5

[0073] Effects of adsorbent and control materials on Cd in water 2+ Comparison of adsorption capacity

[0074] Accurately weigh 0.02 g of two magnetic adsorbents and reference materials (adsorbent A and adsorbent B prepared in Example 1, reference materials 1-9) and add Cd to the mixture at pH 6. 2+In 20 mL of a 100 mg / L solution, an oscillation adsorption test was performed at room temperature and 150 r / min for 12 h. After the solution and the material were separated, the Cd content in the solution was determined using an atomic absorption spectrophotometer. 2+ concentration, and calculate the material's Cd 2+ adsorption amount.

[0075] Depend on Figure 5 From the a in the figure, we can see that adsorbent A has a strong effect on Cd 2+ The adsorption capacity of Cd was 99.8 mg / g. The adsorption capacity of controls 1, 2, 3, 4 and 5 was 99.8 mg / g. 2+ The adsorption capacities were 7.9, 8.9, 14.3, 43.3, and 7.35 mg / g, respectively; Figure 5 In b, adsorbent B has a strong effect on Cd 2+ The adsorption capacity of Cd was 99.9 mg / g, and the control groups 6, 7, 8, 9 and 5 2+ The adsorption capacities of adsorbent materials A and B for Cd 2+ The adsorption capacity of the magnetic material is significantly better than that of the control material, which shows that the improved adsorbent preparation method has a good effect and can greatly improve the adsorption capacity of heavy metals by magnetic materials.

[0076] Example 6

[0077] Initial Cd at three temperatures 2+ Effect of concentration on adsorption effect

[0078] 0.02 g of two adsorbents (adsorbent A and adsorbent B prepared in Example 1) were added to different initial Cd 2+ The concentrations of 10, 20, 50, 80, 100, 150, 200, 250, 300, and 400 mg / L of pH 6 were respectively shaken at 150 r / min for 12 h at 15°C, 25°C, and 35°C. The materials were then magnetically separated and the solution was taken to determine Cd. 2+ concentration.

[0079] Depend on Figure 6 It can be seen that at 15℃, as the initial Cd 2+ With the increase of Cd concentration, the adsorption capacity of both adsorbents increased, among which the adsorption capacity of adsorbent B increased faster; 2+ When the concentration is between 150 and 400 mg / L, the adsorption capacity of the two adsorbents tends to be balanced. 2+ When the concentration was 400 mg / L, the adsorption capacities of the two adsorbents were 131.8 mg / g and 156.0 mg / g, respectively. Figure 6 a); at 25℃ ( Figure 6 b), the adsorption amount increases with the2+ The concentration of Cd increases rapidly. 2+ When the concentration is between 200 and 400 mg / L, the adsorption capacity tends to be balanced. 2+ When the concentration was 400 mg / L, the two adsorbents had the maximum adsorption capacity, which were 133.2 mg / g and 163.4 mg / g respectively; at 35℃ ( Figure 6 c) in the figure, with the initial Cd 2+ With the increase of Cd concentration, the adsorption amount increases rapidly; 2+ When the concentration is between 250 and 400 mg / L, the adsorption capacity tends to be balanced. 2+ When the concentration was 400 mg / L, the two adsorbents had the maximum adsorption capacity, which were 150.5 mg / g and 177.4 mg / g, respectively.

[0080] Example 7

[0081] Effect of adsorption time on adsorption effect

[0082] 0.02 g of two adsorbents (adsorbent A and adsorbent B prepared in Example 1) were added to a 200 mg / L Cd 2+ The experiment was carried out at room temperature and 150 r / min shaking speed in 20 mL solution with a pH of 6. Samples were taken at different time intervals (5, 10, 20, 30, 60, 90, 120, 240, 360, 720 min). After the material was magnetically separated, the solution was taken to determine the Cd 2+ concentration.

[0083] from Figure 7 It can be seen that for Cd 2+ The adsorption capacity of each of the two adsorbents increased rapidly with time. After 30 to 90 minutes of adsorption, the adsorption capacity gradually slowed down and approached equilibrium. After 90 to 120 minutes of adsorption, the adsorption capacity gradually slowed down and approached equilibrium. Adsorbent A approached adsorption equilibrium at 120 minutes, with a final equilibrium adsorption capacity of 124.3 mg / g. Adsorbent B approached adsorption equilibrium at 120 minutes of adsorption, with a final equilibrium adsorption capacity of 148.2 mg / g. The above experimental results show that the time for adsorbents A and B to approach adsorption equilibrium is 120 minutes, indicating that they have a faster adsorption rate.

[0084] Example 8

[0085] Adsorption effect of adsorbent on other heavy metals

[0086] 0.02 g of two adsorbents (adsorbent A and adsorbent B prepared in Example 1) were added to the slurry containing 20, 50, 100 and 200 mg / L Zn 2+ 、Cu 2+ and Pb2+ The experiment was carried out at room temperature and shaken at 150 r / min for 12 hours. After the material was magnetically separated, the solution was taken to determine the Zn 2+ 、Cu 2+ and Pb 2+ concentration.

[0087] from Figure 8 It can be seen from a in the figure that adsorbent A has a strong effect on Zn 2+ 、Cu 2+ and Pb 2+ The adsorption amount increases with the increase of initial concentration. 2+ 、Cu 2+ and Pb 2+ When the initial concentrations were 20, 50 and 100 mg / L, the adsorption capacity of adsorbent A for the three heavy metals was close to 20, 50 and 100 mg / g, and the removal rate was almost 100%. 2+ 、Cu 2+ and Pb 2+ When the initial concentration is 200 mg / L, the adsorbent A has a great effect on the absorption of Zn 2+ 、Cu 2+ and Pb 2+ The adsorption capacities were 120.4, 152.7 and 194.7 mg / g respectively for Pb 2+ The adsorption effect is the best. Figure 8 As can be seen from b in the figure, adsorbent B has a strong effect on Zn 2+ 、Cu 2+ and Pb 2+ The adsorption amount also increases with the increase of initial concentration. 2+ 、Cu 2 + and Pb 2+ When the initial concentrations were 20, 50 and 100 mg / L, the removal rates of adsorbent B for the three heavy metals were almost 100%. 2+ 、Cu 2+ and Pb 2+ When the initial concentration is 200 mg / L, the adsorbent B has a 2+ 、Cu 2+ and Pb 2+ The adsorption capacities were 140.1, 153.0 and 199.7 mg / g respectively. 2+ The above experimental results show that the two adsorbents have the best adsorption effect on Zn 2+ 、Cu 2+ and Pb 2+ It also has a good adsorption removal effect. When the initial concentration is 20, 50 and 100 mg / L, the removal rate of the three heavy metals is almost 100%. When the concentration is 200 mg / L, the removal rate of Pb2+ The adsorption capacities were 194.7 and 199.7 mg / g respectively, and the removal rates were close to 100%.

[0088] The above embodiments are only preferred implementation modes of the present invention and are only used to explain the present invention rather than to limit the present invention. Any changes, substitutions, modifications, etc. made by those skilled in the art without departing from the spirit of the present invention should fall within the scope of protection of the present invention.

Claims

1. The magnetic adsorbent for efficient removal of heavy metals in water bodies is used in heavy metal polluted water bodies, characterized in that: The preparation method of the magnetic adsorbent for efficiently removing heavy metals in water comprises the following steps: (1) adding shell powder to a mixed solution of ferric salt and ferrous salt, adding alkali to adjust the pH to 9-11, stirring for reaction, heating for reaction, washing, and magnetic separation to obtain a magnetic substance; the shell powder is shell powder obtained by passing through an 80-200 mesh sieve; the ferric salt and ferrous salt are ferric citrate and ferrous sulfate, respectively; (2) The magnetic material obtained in step (1) is subjected to high-temperature treatment in an oxidizing atmosphere to obtain a magnetic adsorbent that is efficient in removing heavy metals from water; the temperature of the high-temperature treatment is 600°C; the time of the high-temperature treatment is 1 to 5 hours; and the heating rate is 200 to 800°C / h.

2. The magnetic adsorbent for efficiently removing heavy metals from water bodies according to claim 1 is used in heavy metal-contaminated water bodies, characterized in that: The shell powder in step (1) is at least one of clam powder and apple snail shell powder.

3. The magnetic adsorbent for efficiently removing heavy metals from water bodies according to claim 1 is used in heavy metal-contaminated water bodies, characterized in that: The molar ratio of the trivalent iron in the trivalent iron salt to the divalent iron in the divalent iron salt in step (1) is 1:1 to 3:

1.

4. The magnetic adsorbent for efficiently removing heavy metals from water bodies according to claim 1 is used in heavy metal-contaminated water bodies, characterized in that: The solvent of the mixed solution of the ferric salt and the ferrous salt in step (1) is water; The concentration of the ferric salt in the mixed solution of the ferric salt and the ferrous salt in step (1) is 23.0-69.1 g / L.

5. The magnetic adsorbent for efficiently removing heavy metals from water bodies according to claim 1 is used in heavy metal-contaminated water bodies, characterized in that: In step (1), the pH is adjusted to 10; and the base is aqueous ammonia.

6. The magnetic adsorbent for efficiently removing heavy metals from water bodies according to claim 1 is used in heavy metal-contaminated water bodies, characterized in that: The stirring reaction time in step (1) is 20 to 40 minutes; The temperature of the heating reaction in step (1) is 100-130° C., and the time is 12-36 hours.

7. The magnetic adsorbent for efficiently removing heavy metals from water bodies according to claim 1 is used in heavy metal-contaminated water bodies, characterized in that: The oxidizing atmosphere in step (2) is oxygen or air.

8. The use according to claim 1, characterized in that The heavy metal is Cd 2+ 、Zn 2+ 、Cu 2+ and Pb 2+ At least one of .

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