CN112452300B - Organic phosphorus composite material and preparation method and application thereof - Google Patents

Abstract

The invention belongs to the technical field of heavy metal adsorption, and in particular relates to a preparation method and application of an organophosphorus-hydroxyl aluminum composite adsorption material for efficiently adsorbing heavy metal Cd ²⁺ . The raw materials are aluminum salt and phytic acid. The preparation method specifically includes the following steps: 1) Dissolving the aluminum salt in water, adding phytic acid powder under stirring conditions to obtain a mixed solution of aluminum salt-phytic acid, and stirring for about 1 hour, mixing The molar ratio of P:Al in the solution is 0.01~0.1; 2) Use dilute sodium hydroxide solution to adjust the pH of the mixed suspension to about 6.5, stabilize it for 0.5 h, centrifuge, filter, and freeze-dry to prepare the organophosphorus-loaded hydroxyl aluminum compound Material. Through the water adsorption reaction, the maximum adsorption capacity of the composite material for Cd ²⁺ reaches 205 mg/g, and a stable inner ring complex is formed on the surface of the material. The raw material cost of the material is low, the synthesis process is simple, and the material has broad prospects in the field of treating Cd polluted wastewater.

Description

A kind of organophosphorus composite material and its preparation method and application

technical field

The invention belongs to the technical field of heavy metal adsorption, in particular to the technical field of removal and treatment of heavy metals in water, and specifically relates to an organophosphorus-hydroxyl aluminum composite adsorption material for efficiently adsorbing heavy metal Cd ²⁺ and its preparation method and application.

Background technique

Cadmium is a highly toxic heavy metal. With the development of industry and agriculture, the unreasonable use of pesticides and fertilizers has made the situation of cadmium pollution in my country more serious. Cadmium is not easy to degrade in the environment and has strong mobility. It is a non-essential element for animals and plants. It has certain volatility and can be teratogenic, carcinogenic, and mutagenic. harm. At present, the methods commonly used to repair cadmium pollution in the environment include adsorption, ion exchange, membrane filtration, biological methods, etc. Among them, the adsorption method is widely used because of its wide source of materials, cost-effectiveness, and less secondary pollution. The development of new adsorbents that are efficient, clean, low-cost, and easy to prepare is a hot direction in the field of water treatment and purification.

At present, active minerals, biochar, and resistant microorganisms are mostly used as adsorbents, but these materials generally have some disadvantages: for example, the preparation conditions of biochar are complicated and the cost is high; the cultivation of microorganisms is complicated and the viability is low; the adsorption efficiency of mineral materials is low, etc. Therefore, it is not suitable for large-scale application. Iron/manganese/aluminum hydroxyl compounds are mostly prepared by alkali precipitation method, which is easy to operate, and the surface of the material is loose and porous, has a large specific surface area, and is rich in hydroxyl groups, which can undergo physical and chemical reactions such as electrostatic adsorption, complexation, and precipitation. Effectively removes heavy metals. Especially the organic modification of iron/manganese/aluminum hydroxide can enrich the functional groups on the surface of the adsorbent and improve its adsorption capacity for heavy metal pollutants. Phosphate compounds can have a strong chelation effect with heavy metals, so they are often used to prepare heavy metal adsorption materials. However, most of the current research focuses on inorganic phosphorus, and less research on organic phosphorus. The organic phosphorus in the soil accounts for 30-65% of the total phosphorus, and the organic phosphorus in the soil with high organic matter is as high as 90%. After the crop absorbs it, it can form a variety of organic phosphorus in the body, such as phytic acid. Therefore, this raw material is a low-cost, readily available materials.

Huihui and Huang used amorphous aluminum hydroxide-bacteria composites to adsorb Cd ²⁺ , but found that the bacteria-modified amorphous aluminum hydroxide materials had no obvious effect on the adsorption of Cd ²⁺ in neutral and alkaline environments. Su Yan et al. found that the maximum adsorption capacity _qmax of aluminum hydroxide-polyacrylamide composites at temperatures of 10°C, 30°C, and 50° ^C were 44.43mg/g, 50.11mg/g, respectively. and 54.81mg/g. Sheng Jiao et al. found that the adsorption material of phytic acid composite sepiolite had the best adsorption performance at pH 3.8 when the adsorbent concentration was 18g/L at 30°C, and the maximum adsorption capacity for Cd ²⁺ was 2.67mg/g. It is not difficult to find that these materials have certain limitations in the adsorption of Cd ²⁺ , so this study developed a new organophosphorus-supported hydroxyl aluminum composite material that can efficiently adsorb Cd ²⁺ .

references:

1. Du HH, Huang, QY, Yang RJ, Tie BQ, Lei M Cd sequestration by bacteria–aluminum hydroxide composites[J].CHEMOSPHERE,2018,198,75-82.

2. Su Yan, Liu Renyuan, Chen Zhenling. Study on the adsorption of cadmium ions by nano-aluminum hydroxide-polyacrylamide composite flocculant[J]. Ion Exchange and Adsorption, 2016,32(04):324-332.

3. Sheng Jiao, Zeng Guihua, Yan Shumei, He Aicui, Liu Ying. Adsorption of Cd ²⁺ by Phytic Acid Sepiolite Composite Heavy Metal Adsorbent[J]. Anhui Agricultural Sciences, 2013,41(24):10087-10088.

Contents of the invention

The purpose of the present invention is to provide an organophosphorus composite material, which can efficiently adsorb Cd ²⁺ , is simple to prepare and does not cause secondary pollution.

A kind of organophosphorus composite material, its structural formula is as follows:

The preparation method of described organophosphorus composite material, comprises the following steps:

S1, adding organophosphorus to the aluminum salt, mixing evenly, adjusting the pH value, centrifuging and filtering to obtain a precipitate;

S2. Freeze-drying the precipitate to obtain an organophosphorus composite material.

Preferably, the aluminum salt is a water-soluble aluminum salt.

Only water-soluble aluminum salts can be dissolved in water to adjust the hydrolysis balance, and then the aluminum salts can be converted into amorphous hydroxyaluminum to prepare the organophosphorus composite material required by the present invention.

Preferably, the water-soluble aluminum salt is one or more of aluminum chloride, aluminum chloride hydrate, aluminum nitrate, aluminum nitrate hydrate, aluminum sulfate, and aluminum sulfate hydrate.

Further preferably, the aluminum salt is aluminum nitrate hydrate.

Aluminum nitrate has low density, good solubility, and is easily soluble in water, ethanol, acetone, and nitric acid. Moreover, the nitrate ion is easy to remove and has little interference to the composite material. Aluminum nitrate nonahydrate is the most stable form of aluminum nitrate.

Preferably, the mixing is stirring and mixing with a magnetic stirrer at a rotational speed of 150-500 rpm.

Preferably, the organic phosphorus is phytic acid.

Phytic acid is the most abundant organophosphate in most soils and sediments. It contains a large number of phosphate groups and is a rare metal polydentate chelating agent. Some studies have found that phytic acid can increase the concentration of Cd ²⁺ in heavy metal-polluted soils. The leaching rate and the amount of leaching. Moreover, phytic acid is low-cost, easy to obtain, and exists in large quantities in the natural environment.

Preferably, the molar ratio of P:Al in the organophosphorus composite material is 1:(10-100).

The molecular weight of phytic acid is large, and the molar ratio of P:Al is too high, which increases the application amount of composite materials in practical applications, thereby increasing the cost, and aluminum hydroxy has a certain upper limit for the adsorption of phytic acid; the molar ratio of P:Al is too low, The modification of hydroxyaluminum is not obvious.

Further preferably, to simulate the mineral-organic composite ratio in the natural environment, and considering the practical application of the restoration agent, the molar ratio of P:Al in the organophosphorus composite material is 0.1.

Preferably, the step S1 adjusts the pH value to 6.5±0.2, and adjusts the pH with a dilute alkali solution.

The pH needs to be controlled at 6.5±0.2. At a pH of about 5, aluminum ions begin to precipitate, further ensuring complete conversion. Controlling the pH at about 6.5 means that there is no need to add alkali. Excessive alkali can easily turn aluminum hydroxide into metaaluminate .

Further preferably, the alkaline solution may be NaOH solution or KOH solution.

Preferably, after adjusting the pH value in step S1, it is stabilized for 0.5 h, during which the pH is fine-tuned and centrifuged.

The present invention also provides the application of the organic phosphorus composite material to adsorb heavy metal Cd ²⁺ , the specific method is:

Add organophosphorus composite material into the centrifuge tube, test the ratio of organophosphorus composite material and heavy metal cadmium at 100 mg:(0-4) mg, and control the pH at 6.5±0.05. The sample was shaken in a constant temperature shaker (25°C) for 24 hours and then filtered. The Cd ²⁺ concentration was measured by ICP (Inductively Coupled Plasma Mass Spectrometry), and the adsorption amount was calculated according to the difference between the Cd ²⁺ concentration before and after adsorption. The theoretical adsorption capacity of organophosphorus composite materials can reach 205mg/g, which has good heavy metal adsorption effect.

The present invention is further elaborated below:

The invention selects pure hydroxyl aluminum and phytic acid as raw materials to prepare composite materials. Aluminum hydroxy compounds are widely found in aquatic and geological environments. They have large surface areas and abundant hydroxyl functional groups, which can effectively adsorb metals. Phytic acid is the most abundant organophosphate in most soils and sediments. It contains a large amount of phosphoric acid Phytic acid is a rare metal polydentate chelating agent. Some studies have found that phytic acid can increase the leaching speed and amount of Cd ²⁺ in heavy metal polluted soil. Compared with other iron/manganese hydroxyl compounds, the adsorption of phytic acid by aluminum (hydr) oxide is carried out through the coordination exchange between H ₂ O and -OH groups on the surface and phosphoric acid groups. Therefore, the adsorption process releases OH-, while the adsorption promotes the deprotonation of the phosphate group. Infrared spectroscopy showed that phytic acid was adsorbed on aluminum hydroxy to form Al–O–P bonds. Pure hydroxyaluminum has a higher density of active sites and better binding ability to phytic acid, with an adsorption capacity of 1.70 mol/kg (34.3 μmol/m ² ), while gibbsite and bayerite adsorbed phytic acid respectively Only 0.52 μmol/m ² and 0.4 μmol/m ² . Solution chemical analysis, infrared spectrum characterization and quantum chemical theoretical calculations showed that phytic acid was adsorbed on the surface of hydroxyaluminum through three phosphoric acid groups.

The invention adopts the alkali precipitation method to prepare, and the operation is simple. The composite material can significantly adsorb Cd ²⁺ . On the one hand, the addition of phytic acid increases the negative charge on the surface of aluminum hydroxy, thereby enhancing the electrostatic adsorption capacity for Cd ²⁺ . The multiple phosphate groups of phytic acid on the aluminum surface complexed with Cd ²⁺ to form Al-IHP-Cd ternary complex, thereby increasing the adsorption amount of Cd ²⁺ .

The advantages of the present invention are as follows:

1. The method of the present invention is simple to prepare, and is carried out at normal temperature and pressure without special conditions

2. The phytic acid described in the present invention is a low-cost, easy-to-obtain organophosphorus material, which is common and abundant in the natural environment.

3. The raw materials of the present invention are widely present in the natural environment, and are composed of mineral-organic complexes in simulated soil environments, which have little change in the physical and chemical properties of the matrix and are not easy to cause secondary pollution.

4. The present invention loads phytic acid on the surface of hydroxyaluminum, improves its physical and chemical properties, and improves the adsorption performance to cadmium.

5. In the phytic acid-hydroxyaluminum-cadmium ternary system of the present invention, Cd not only reacts with the –OH of hydroxaluminum, but also reacts with the phosphoric acid group _–PO of phytic acid, and generates Al-IHP-Cd stable The complex has a maximum adsorption capacity of 205mg/g (~20wt.%) for Cd ²⁺ , which is far greater than other types of adsorbents.

The complex provided by the invention can also be applied to adsorb and remove other heavy metals (Pb ²⁺ , Cu ²⁺ , Ni ²⁺ , Zn ^{2 +} ) with similar properties in water bodies.

Description of drawings

Figure 1 is the TEM spectrum of pure hydroxyaluminum (AAH), low-concentration organophosphorus-supported hydroxyaluminum composite material (AAH-OP_low), and high-concentration organophosphorus-supported hydroxyaluminum composite material (AAH-OP_high) in the examples of the present invention.

Fig. 2 is the XRD patterns of pure aluminum hydroxy (AAH), low-concentration organophosphorus-supported aluminum hydroxy composite material (AAH-OP_low), and high-concentration organophosphorus-supported aluminum hydroxy composite material (AAH-OP_high) in the implementation case.

Fig. 3 is the FTIR spectra of pure aluminum hydroxy (AAH), low-concentration organophosphorus-supported aluminum hydroxy composite material (AAH-OP_low), and high-concentration organophosphorus-supported aluminum hydroxy composite material (AAH-OP_high) in the implementation case.

Figure 4 is a schematic diagram of the structure of phytic acid supported aluminum hydroxy

Figure 5 shows the adsorption isotherms of pure hydroxyaluminum (AAH), low-concentration organophosphorus-supported hydroxyaluminum composite (AAH-OP_low), and high-concentration organophosphorus-supported hydroxyaluminum composite (AAH-OP_high) on Cd ²⁺ in the adsorption performance test Wire.

Figure 6 is a comparison of the NMR spectra of pure aluminum hydroxy (AAH) and organophosphorus-supported aluminum hydroxy composites before and after adsorption of Cd ²⁺ in the adsorption performance test.

Fig. 7 is a comparison of FTIR spectra before and after adsorption of Cd ²⁺ by pure aluminum hydroxy (AAH) and organophosphorus-supported aluminum hydroxy composites in the adsorption performance test.

Fig. 8 is a pH adsorption experiment spectrum of Cd ²⁺ on a high-concentration organophosphorus-supported aluminum hydroxy composite material (AAH-OP_high).

Detailed ways

The present invention will be further described below in conjunction with specific preferred embodiments, but the protection scope of the present invention is not limited thereby.

Example 1

Two concentrations of organophosphorus-supported hydroxyl aluminum composites were prepared, and pure hydroxyl aluminum was used as a reference to explore the surface morphology, functional group potential and spatial structure of the composites. Proceed as follows:

The synthesis steps of organophosphorus-loaded hydroxyl aluminum composite materials are as follows: accurately weigh 0.05mol aluminum nitrate nonahydrate (Al(NO ₃ ) ₃ 9H ₂ O) and dissolve it in 500mL deionized water, stir the solution with a magnetic stirrer, and take any of them Add 0.33g and 3.3g phytic acid respectively to the two parts, react for 1h, slowly add 1mol/L NaOH solution to the solution, adjust the pH of the solution to 6.5, stop stirring after 0.5h of stabilization, and suspend the synthesized organophosphorus-loaded hydroxyaluminum complex The liquid was centrifuged to remove the supernatant, this step was repeated 3 times, and the preparation was completed after freeze-drying.

The surface ξ potential of the adsorbent was measured by a Zeta potential analyzer (Zetaplus90, Brookhaven). Before the test, each adsorbent was dispersed in a 0.1mol/L _KNO3 solution, and three parallel samples were set for each adsorbent, and the pH was adjusted to 6.5. Put into 25 ℃ constant temperature shaker and balance for 24h. The results are shown in Table 1. The addition of phytic acid changed the surface potential of minerals from positive to negative, and the higher the molar ratio of P:Al in the composite material, the greater the degree of reduction. The reduction of surface negativity increases the electrostatic attraction of the adsorbent to Cd ²⁺ , thereby facilitating its adsorption.

Table 1 The ξ potential table of three kinds of adsorbents under the conditions of pH 6.5 and 0.1mol/L KNO ₃

After the composite sample was vacuum freeze-dried, it was ground into a fine powder with an agate mortar, and its surface morphology was analyzed and determined by a Tecnai G2 F20 S-TWIN transmission electron microscope (TEM, FEI, USA). The results are shown in Figure 1. The synthesized pure aluminum hydroxide is irregular nanoparticles with loose texture, which belongs to amorphous aluminum hydroxide (AAH). The addition of phytic acid in the preparation of the composite has no significant effect on the surface morphology of pure aluminum hydroxide.

The Bruker D8 ADVANCE powder diffractometer (XRD, Bruker, Germany) analyzed and determined the crystal structure of the composite sample. The results are shown in Figure 2. The addition of phytic acid can alleviate the trend of increasing the crystallinity of pure hydroxyaluminum, and the phytic acid on AAH is in the transition stage from surface complexation to surface precipitation.

Use NICOLET 5700 Fourier transform infrared spectrometer (ATR-FTIR, American Thermoelectric Nicolis Instrument Company) to measure its FTIR figure, the result is shown in Figure 3, according to the ATR-FTIR figure, after loading phytic acid, the chemical environment of Al-OH occurred The FTIR spectrum of AAH-OP_high changes more obviously, the Al-OH peak at 946cm ^-1 has a blue shift, and new peaks appear at 883cm ^-1 , 1065cm ^-1 , 1176cm ^-1 and 1724cm ^-1 . 1065cm ^-1 and 1176cm ^-1 correspond to the symmetric and asymmetric stretching vibrations of PO-Al adsorbed on the surface of AAH with phytic acid. The peak at 1724cm ^-1 is CC in phytic acid, the peak at 883cm ^-1 may be generated by the stretching vibration of P-OH, and the peak at 2428cm ^-1 is weakened, which is guessed to be Al-OH in pure hydroxyaluminum impurities with high crystallinity the absorption peak. At pH 6-7, the four phosphate groups in phytic acid are protonated, so no more than four phosphate groups can be complexed with AAH on the surface, mainly three phosphate groups at positions 1, 3, and 5. Therefore, the specific structural formula of the organophosphorus-supported hydroxyaluminum composite material provided by the present invention is shown in Fig. 4 .

Example 2

Adsorption performance test one

The isothermal adsorption experiment of Cd ²⁺ on organophosphorus-supported hydroxyl-aluminum composites, pure hydroxyl-aluminum adsorption of Cd ²⁺ was used as a reference, and the maximum adsorption capacity of the adsorbent was tested at 25°C and pH 6.5.

The experiment was carried out in a 50mL centrifuge tube. The complex prepared in Example 1 was used as the adsorbent. A certain volume of adsorbent and Cd ²⁺ mother liquor were added to the centrifuge tube, and 0.1mol/L KNO ₃ was used to make the volume equal to that of the adsorbent. The final adsorbent concentration is controlled to be 0.1g/L, the Cd ²⁺ concentration is 0-40mg/L, and the pH of the system is adjusted to 6.5. Three parallels were set up for each concentration, and no adsorbent was used as the control. The centrifuge tube was placed in a constant temperature oscillator at 25°C for 24h, centrifuged at 5000g for 15min, the supernatant in the centrifuge tube was passed through a 0.45μm nylon filter membrane, and then the Cd ²⁺ concentration in the filtrate was measured by ICP (Inductively Coupled Plasma Mass Spectrometry). The measured data were fitted with a Langmuir model.

Table 2 embodiment is to the isotherm adsorption line fitting parameter of cadmium

Note: K represents the adsorption affinity constant (L/g), and Q _max represents the maximum adsorption amount (mg/g) obtained by fitting the Langmuir model, which is calculated by the mass of Cd ²⁺ adsorbed per unit mass

According to Figure 5 and Table 2, the adsorption behavior of AAH, AAH-OP_low, and AAH-OP_high on Cd ²⁺ belongs to the monolayer adsorption, which can be well fitted by the Langmuir model, and the adsorption capacity of Cd ²⁺ is ranked as AAH -OP_high>AAH-OP_low>AAH, where the maximum adsorption capacity of AAH-OP_high is 205mg/g, adding high concentration of phytic acid can improve the adsorption performance of Cd ²⁺ .

A Bruker 600M wide-cavity solid-state nuclear magnetic resonance spectrometer (NMR, Bruker, Germany) was used to measure ¹ H NMR spectra, and analyze functional groups and structural information. According to the ¹ H NMR spectrum of Figure 6AAH-OP_high, the chemical environment of H in POH in phytic acid is very similar to that in Al-OH in gibbsite. Compared with the change of H characteristic peak before and after AAH adsorption of Cd ²⁺ , the peak area change range of H characteristic peak before and after AAH-OP_high adsorption of Cd ²⁺ is smaller. This shows that Cd ²⁺ mainly complexes with the –OH contained in the phosphate group of phytic acid, while only a small part of Cd ²⁺ still complexes with the –OH of AAH.

The samples before and after adsorption of Cd ²⁺ on the adsorbent were vacuum freeze-dried, ground into fine powder with an agate mortar, and their FTIR patterns were measured with a NICOLET 5700 Fourier transform infrared spectrometer (ATR-FTIR, American Thermo-Nicole Instruments Inc.). It can be seen from Figure 7 that Cd ²⁺ reacts with both the –OH of AAH and the –OH of the phosphoric acid group of phytic acid. Consistent with the previous experimental data, the addition of phytic acid improves the ability of hydroxyaluminum to adsorb Cd ²⁺ .

Adsorption performance test two

The pH adsorption experiment of organophosphorus-supported hydroxyl aluminum composite materials on Cd ²⁺ was tested to test the effect of adsorbent on the adsorption of Cd ²⁺ under the conditions of 25°C and pH 4-8.

All experiments were carried out in 50mL centrifuge tubes. A series of solutions with a Cd ²⁺ concentration of 20 mg/L were prepared, and a high-concentration organophosphorus-supported aluminum hydroxy composite material (AAH-OP_high) was selected as the adsorbent. The dosage of the adsorbent was 1.0 g/L, and 0.1 mol/L of The volume of KNO ₃ solution was adjusted to 30 mL, and the pH of the solution was adjusted with 1 mol/L NaOH and 1 mol/L HCl, shaken at a constant temperature of 25 °C for 24 h with a constant temperature shaker, and then centrifuged for 15 min. The supernatant in the centrifuge tube was filtered with a 0.45 μm nylon membrane, and then the residual Cd ²⁺ concentration in the supernatant was analyzed by ICP (inductively coupled plasma mass spectrometry).

According to Figure 8, the adsorption capacity of the composite material to Cd ²⁺ increases with the increase of pH in the range of pH 4-8. From the figure, it can be found that the composite material has the ability to adsorb Cd ²⁺ in a neutral to alkaline environment. Excellent adsorption properties.

Comparative case 1

pH Adsorption of Cadmium by the Complex of Aluminum Hydroxide and Bacteria

Use Cd(NO ₃ ) ₃ 4H ₂ O to prepare cadmium mother liquor, the concentration of Cd ²⁺ in the reaction system is 0.1mM, and the concentration of adsorbent (amorphous aluminum hydroxide, aluminum hydroxide-bacteria complex in different proportions) is 1g/ L, with 0.1mol/L _KNO3 solution to make the volume to 30mL, no adsorbent was added to the control group. Use 1 mol/L NaOH, 1 mol/L HNO ₃ to adjust the pH of the suspension to 4-7, shake it at a constant temperature of 25°C for 24 hours with a constant temperature shaker to allow adsorption to balance, and then centrifuge. The supernatant was filtered with a 0.45 μm nylon membrane, and the concentration of residual Cd ²⁺ in the supernatant was analyzed by atomic absorption spectrometry.

The adsorption capacity of each adsorbent for Cd ²⁺ increases with the increase of pH. When the pH is less than 6, the adsorption performance of the complex for Cd ²⁺ is better than that of pure aluminum hydroxide. At pH 6-7, The modification of aluminum hydroxide material by bacteria did not significantly improve the adsorption performance of aluminum hydroxide material, and the adsorption capacity was about 7.9mg/g.

Comparative case 2

Adsorption Isotherm of Aluminum Hydroxide-Polyacrylamide for Cd ²⁺

For cadmium stock solution (1.000g/L), add 220mg of aluminum hydroxide-polyacrylamide solution into an Erlenmeyer flask filled with 400mL of cadmium solution, place the Erlenmeyer flask in a rotary shaker for 4 hours, and the shaker speed is 180r /min. Then the solution was centrifuged, and the supernatant was taken to measure the Cd ²⁺ concentration by an atomic absorption spectrophotometer.

In the studied temperature range, the Langmuir isotherm adsorption model is more consistent with the adsorption isotherm data of aluminum hydroxide-polyacrylamide on Cd ²⁺ . This indicates that Cd ²⁺ forms a monolayer adsorption layer on the surface of aluminum hydroxide-polyacrylamide. At 10°C, 30°C, and 50°C, the maximum adsorption capacity q _max of aluminum hydroxide-polyacrylamide to Cd ²⁺ is 44.43mg/g, 50.11mg/g, and 54.81mg/g, respectively.

Comparative case 3

Adsorption of Cd ²⁺ by Phytic Acid Sepiolite Composite Heavy Metal Adsorbent

Using phytic acid and sepiolite as raw materials, a phytic acid-sepiolite composite adsorption material was prepared. The temperature was 30°C, the concentration of the adsorbent was 18g/L, the concentration of Cd ²⁺ was 100mg/L, and the pH was adjusted from 1 to 6 for pH adsorption. Experiment; the temperature is 30°C, the adsorbent concentration is 18g/L, and the pH is 3.8 to treat solutions with different cadmium concentrations to explore the influence of heavy metal concentration on adsorption performance;

The research results show that the phytic acid sepiolite composite heavy metal adsorbent has the best adsorption performance at pH=3.8 when the adsorbent concentration is 18g/L at 30°C, and the maximum adsorption capacity is 2.67mg/g.

From performance tests and comparison cases, it can be found that organophosphorus-supported hydroxyaluminum has a good adsorption effect on Cd ²⁺ , which is higher than the normal adsorption capacity (~50mg/g) of the existing technology. The addition of high-concentration organophosphorus can significantly enhance the adsorption Performance, the maximum adsorption capacity of Cd ²⁺ can reach more than 205mg/g, more than four times the normal adsorption capacity of the existing technology. The invention has the advantages of simple preparation, low cost, higher adsorption capacity than other inventions, and high industrial and agricultural popularization value.

The above is only a preferred embodiment of the application, and does not limit the application in any form. Although the application is disclosed as above with the preferred embodiment, it is not intended to limit the application. Any skilled person familiar with this field, Without departing from the scope of the technical solution of the present application, any changes or modifications made using the technical content disclosed above are equivalent to equivalent implementation cases, and all belong to the scope of the technical solution.

Claims (6)

1. The application of the organic phosphorus composite material in heavy metal adsorption is characterized in that the structural formula of the organic phosphorus composite material is as follows:

。

2. the use according to claim 1, wherein the organophosphorus composite material is prepared by a method comprising the following steps:

s1, adding organic phosphorus into an aluminum salt solution, uniformly mixing, adjusting the pH value, centrifuging and filtering to obtain a precipitate;

s2, freeze-drying the precipitate to obtain an organic phosphorus composite material;

the organic phosphorus is phytic acid;

the aluminum salt is water-soluble aluminum salt; the molar ratio of P to Al in the organophosphorus composite material is 1 (10 to 100); and S1, adjusting the pH value to 6.5 +/-0.2, and adjusting the pH value by using a dilute NaOH solution.

3. The use according to claim 2, wherein the water-soluble aluminum salt is one or more of aluminum chloride, aluminum chloride hydrate, aluminum nitrate hydrate, aluminum sulfate and aluminum sulfate hydrate.

4. Use according to claim 2, characterized in that the water-soluble aluminium salt is aluminium nitrate hydrate.

5. Use according to claim 2, wherein the molar ratio of P to Al in the organophosphorus composite material is 1.

6. Use according to claim 2, wherein step S1 is carried out by adjusting the pH to a value of 0.5h, during which the pH is finely adjusted, followed by centrifugation.

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