CN112371078A - Phosphate removal method based on activated load bentonite - Google Patents

Abstract

The invention discloses a phosphate removal method based on activated load bentonite, and belongs to the technical field of phosphorus removal. According to the method, the hydroxyl aluminum load bentonite is used as an adsorption material, the pH, the temperature and the initial concentration of phosphate are used as influence factors, the equilibrium adsorption quantity of phosphate is used as a response value, a response regression model is established, response surface design and variance analysis are carried out, the pH, the temperature and the initial concentration of phosphate solution are selected according to results, and the hydroxyl aluminum load bentonite is added to remove the phosphate. According to the invention, on the premise of not destroying the phosphate adsorption capacity of the aluminum hydroxide-loaded bentonite, the initial adsorption rate of the aluminum hydroxide-loaded bentonite to phosphate is improved, and the industrial application efficiency can be effectively improved.

Description

Phosphate removal method based on activated load bentonite

Technical Field

The invention relates to the technical field of phosphorus removal, and particularly relates to a phosphate removal method based on activated load bentonite.

Background

The eutrophication of water bodies is always an environmental problem which is concerned by the world, and the eutrophication of water bodies is particularly important for preventing and treating the eutrophication of water bodies while the eutrophication of water bodies continuously threatens the normal production and life of human beings and causes huge burden on social economy by influencing fishery, water consumption, tourism and the like. Research shows that phosphorus is a more critical factor for water eutrophication. At present, the domestic and foreign phosphorus removal methods mainly comprise chemical precipitation, biological removal, adsorption and the like. Among them, adsorption phosphorus removal is considered to be a promising phosphorus removal method due to low cost, high efficiency, good stability, realization of phosphorus recovery, and the like. Since phosphorus in natural water exists mainly in the form of phosphate, adsorption of phosphate in water is the key point in research on phosphorus removal technology.

Bentonite is a cheap clay mineral, and is often selected as an adsorption raw material for sewage treatment due to its high cation exchange capacity and excellent adsorption performance. Research shows that unmodified bentonite has low adsorption performance on phosphate and other anions, and if the bentonite is used for adsorbing phosphate in water, bentonite raw soil is generally required to be activated or subjected to inorganic loading. At present, the research on phosphate adsorption of aluminum hydroxide-loaded bentonite is mature, but independent loading and inorganic-organic compounding are mainly used, the inorganic-organic compounding process is complex, the required conditions are high, and acid activated aluminum hydroxide-loaded bentonite is not used for adsorbing phosphate in the prior art.

Disclosure of Invention

[ problem ] to

Before the unmodified bentonite is used for adsorbing anions such as phosphate, the bentonite raw soil needs to be activated or inorganic loaded, so that the process is complicated and the required conditions are high.

[ solution ]

The invention provides a preparation method of hydroxyl aluminum loaded bentonite, which comprises the following steps:

the method comprises the following steps: acidifying the bentonite with a sulfuric acid solution to obtain acid activated bentonite;

step two: adding acid activated bentonite into a pillaring agent, stirring, aging at constant temperature, and centrifuging to wash the product until no Cl is generated^-Drying, grinding and sieving to obtain the hydroxyl aluminum loaded bentonite.

In one embodiment of the present invention, the sulfuric acid solution has a mass concentration of 20%.

In one embodiment of the present invention, the ratio of the amount of the sulfuric acid solution to the amount of the bentonite is 1g of bentonite added to 10mL of sulfuric acid solution.

In one embodiment of the invention, the acid-activated bentonite added to the pillaring agent is Al-activated³⁺10 mmol/g of soil^-1And (4) weighing.

In one embodiment of the present invention, the preparation method of the pillaring agent is: 0.6 mol/L^-1NaOH solution was added dropwise to the solution in an amount of 1.0 mol/L^-1AlCl₃Solution of the components in such a way that the molar ratio OH is^-/Al³⁺And (5) aging at constant temperature, namely 2.4. .

In one embodiment of the present invention, the drying temperature is 90 ℃.

In one embodiment of the invention, the mesh number is 150.

In one embodiment of the invention, the acid-activated bentonite is added to the pillaring agent separately, stirred at 60 ℃ for 5h, and aged at constant temperature for 12 h.

The invention also provides a phosphate removal method based on activated load bentonite, which comprises the following steps: the method comprises the steps of establishing a response regression model by using the hydroxyl aluminum loaded bentonite as an adsorption material, the pH, the temperature and the initial concentration of phosphate as influence factors and the equilibrium adsorption quantity of phosphate as a response value, carrying out response surface design and variance analysis, selecting the pH, the temperature and the initial concentration of a phosphate solution according to results, and adding the hydroxyl aluminum loaded bentonite to remove the phosphate.

In one embodiment of the present invention, the phosphate adsorption amount is calculated as follows:

in the formula: q. q.s_eThe equilibrium adsorption amount of the soil sample to phosphate is mg.g^-1；C₀And C_eRespectively the initial concentration and the equilibrium concentration of phosphate in the solution, mg.L^-1(ii) a m is the mass of the hydroxyl aluminum load bentonite, g; v is the volume of phosphate solution, mL.

[ advantageous effects ]

The phosphate adsorbing material disclosed by the invention has a good adsorbing effect in phosphorus-containing wastewater with a high concentration (50-100 mg/L), and can be used for standard-reaching discharge treatment of industrial high-concentration phosphate wastewater. Meanwhile, the phosphate adsorbing material is cheap in production raw materials and has certain economic benefit.

According to the invention, on the premise of not destroying the phosphate adsorption capacity of the aluminum hydroxide-loaded bentonite, the initial adsorption rate of the aluminum hydroxide-loaded bentonite to phosphate is improved, and the industrial application efficiency can be effectively improved.

Drawings

FIG. 1 shows various soil samples (Bent, H)⁺-Bent、Al₁₃-Bent、H⁺-Al₁₃-Bent).

FIGS. 2(a) -2 (h) are SEM-EDS images of various soil samples; (a, b, c, d represent Bent, H, respectively⁺-Bent、 Al₁₃-Bent、H⁺-Al₁₃SEM picture of Bent; e. f, g and h are corresponding EDS energy spectrograms).

FIG. 3 is initial phosphate concentration vs. Al₁₃-Bent、H⁺-Al₁₃Effect curve of Bent adsorption of phosphate.

FIG. 4 shows Al₁₃-Bent、H⁺-Al₁₃Bent adsorption isotherms.

FIG. 5 shows Al₁₃-Bent、H⁺-Al₁₃Bent adsorption kinetics curves.

FIG. 6 is pH vs. Al₁₃-Bent、H⁺-Al₁₃Effect curve of Bent adsorption of phosphate.

FIG. 7 is a comparison of measured phosphate adsorption versus predicted values.

FIGS. 8(a) -8 (c) are graphs of respective response surfaces; (a) pH-initial concentration interaction term; (b) a pH-temperature interaction term; (c) temperature-initial concentration interaction term.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples.

Example 1

This example provides a method for removing phosphate based on activated supported bentonite using the following reagents and instruments:

the main reagents are as follows: aluminium chloride hexahydrate (AlCl)₃·6H₂O, AR), sodium hydroxide (NaOH, AR), potassium dihydrogen phosphate (KH)₂PO₄AR), silver nitrate (AgNO)₃AR) is purchased from chemical reagents of national drug group, while bentonite is purchased from Anji of Zhejiang, and the experimental water is distilled water.

The main apparatus is as follows: SHA-B constant temperature oscillator (shanghai li bangxi instruments science and technology ltd, china), FE20 laboratory pH meter (mettler-toledo instruments ltd, switzerland), ultraviolet-visible spectrophotometer (shanghai instruments electric analyzer ltd, china), PANalytical X' per PRO type X-ray diffractometer (PANalytical, netherlands), SU5000 type thermal field emission scanning electron microscope (hiti, japan).

The method comprises the following steps:

the method comprises the following steps: activating bentonite acid, weighing 20g of bentonite in a 250mL conical flask with a plug, adding 20% sulfuric acid into the bentonite according to the solid-to-liquid ratio of 1:10 (1g of bentonite and 10mL of sulfuric acid), stirring at the constant temperature of 60 ℃ for 2h, centrifuging at medium speed (about 4000-6000 r/min), discarding the supernatant, washing the soil sample with distilled water to pH>Drying at 4, 95 deg.C for 4 hr, grinding, and sieving with 150 mesh sieve to obtain acid activated bentonite (H)⁺-Bent)。

Step two: carrying out the preparation of the load bentonite: at 60 ℃ 800 r.min^-1Under the condition, 0.6 mol.L^-1Slowly dropping NaOH solution into the solution at a concentration of 1.0 mol.L^-1AlCl₃Solution of the components in such a way that the molar ratio OH is^-/Al³⁺Aging for 24h at constant temperature (2.4) to obtain the aluminum hydroxide pillaring agent. According to Al ³⁺10 mmol/g of soil^-1Weighing a certain amount of bentonite (Bent) and acid activated bentonite (H)⁺-Bent) is added into a hydroxy aluminum pillaring agent respectively, stirred for 5h at 60 ℃, aged for 12h at constant temperature, and the product is centrifugally washed until no Cl is generated^-(AgNO₃Detection), drying at 90 ℃, grinding and sieving with a 150-mesh sieve to respectively obtain the aluminum hydroxide load bentonite (Al)₁₃-Bent and H⁺-Al₁₃-Bent)。

Step three: a phosphate adsorption experiment is carried out by adopting a batch equilibrium method, and phosphate standard solutions with various concentrations used in the experiment are prepared according to a method in the national standard (GB 11893-89). Accurately weighing 0.1g of bentonite sample in a 150mL conical flask, adding 25mL of phosphate solution with certain concentration, and heating at 30 ℃ for 170 r.min^-1Shaking for 5h (equilibrium is reached), filtering, separating, measuring the phosphate concentration (in P) in the filtrate by using an ultraviolet spectrophotometer, and calculating the phosphate adsorption amount according to the formula (3). All experiments were repeated 3 times and the results averaged.

In the formula: q. q.s_eThe equilibrium adsorption amount of the soil sample to phosphate is mg.g^-1；C₀And C_eRespectively the initial concentration and the equilibrium concentration of phosphate in the solution, mg.L^-1(ii) a m is the soil sample mass, g; v is the volume of phosphate solution, mL.

Adsorption equilibrium data were fitted to Langmuir (equation (4)), Freundlich (equation (5)), and Sips (equation (6)) adsorption isotherms, as follows:

in the formula: q. q.s_mMaximum equilibrium adsorption, mg. g, was fitted to Langmuir^-1；K_LIs Langmuir constant, L.mg^-1；K_FAnd 1/n are both Freundlich parameters; q. q.s_msFitting maximum equilibrium adsorption capacity, mg. g, for Sims^-1；K_sFor the parameters of Sims, (L. mg)^-1)^ms(ii) a And ms is a Sips parameter for representing the nonuniformity of the system, and the value range of the ms is 0-1.

And calculating the adsorption amount of the phosphate. Adsorption equilibrium data were fitted using pseudo first order kinetics (equation (7)), pseudo second order kinetics (equation (8)), and an Elovich (equation (9)) adsorption kinetics model, as follows:

in the formula: q. q.s_tThe equilibrium adsorption amount at time t, mg.g^-1；k₁Is a pseudo first order kinetic constant, min^-1(ii) a t is reaction time, min; k is a radical of₂As a pseudo-secondary kinetic constant, g.mg^-1·min^-1(ii) a Alpha and beta are constants, mg. g, representing the initial adsorption rate and desorption rate, respectively^-1·min^-1、g·mg^-1。

Characterization analysis

1) XRD Pattern 1 is various soil samples (Bent, H)⁺-Bent、Al₁₃-Bent、H⁺-Al₁₃-Bent). The preparation conditions (temperature, time, etc.) of each soil sample are the same (see steps one to two). From FIG. 1, Bent, H⁺D of Bent₍₀₀₁₎The peak diffraction angle 2 theta is 6.831 degrees and 5.991 degrees respectively, after the bentonite is activated by acid, the diffraction peak is shifted to a small angle, and the interlayer spacing is controlled byIncreasing the thickness of the aluminum oxide layer from 1.293 nm to 1.474nm, wherein ions in the bentonite layer are dissolved out under the action of acid, pore channels are dredged, interlaminar lattices are cracked, Al in the Al-O octahedron is dissolved in the interlaminar to form a hydroxyl layered structure, and the interlayer spacing is enlarged; al compared to unsupported bentonite₁₃-Bent and H⁺-Al₁₃D of Bent₍₀₀₁₎The peak diffraction angles 2 theta are all less than 5 deg., indicating that oligomeric Al ions successfully intercalate the bentonite layer and the interlayer spacing increases significantly.

2) SEM-EDS can generally use SEM image to study soil sample microscopic surface morphology. As is clear from FIGS. 2(a) to 2(H), H is higher than Bent (FIG. 2(a))⁺Some loose structures with thinner sheets appear on the surface of Bent (fig. 2(b)), because impurities such as metal ions in bentonite are dissolved out by acid activation, clay particles are dispersed, and the particles become smaller and thinner; al (Al)₁₃Bent (FIG. 2(c)), H⁺-Al₁₃After being loaded with aluminum hydroxide, Bent (FIG. 2(d)) forms Al-OH clusters, the surface is in a cluster shape, the structure becomes irregular, and the number of adsorption sites increases. As can be seen from the EDS spectrum, the content ratio of aluminum, magnesium, iron and other elements contained in Bent tends to decrease after acid activation, while Al₁₃-Bent、H⁺-Al₁₃An increase in the aluminum element content was clearly seen by Bent, indicating successful loading of bentonite aluminum hydroxy onto the bentonite.

FIG. 3 is initial phosphate concentration vs. Al₁₃-Bent、H⁺-Al₁₃Effect of Bent adsorption of phosphate, as can be seen from the figure, Al₁₃Bent and H⁺-Al₁₃The adsorption capacity of Bent to phosphate increases with the initial concentration and finally reaches equilibrium, while the removal rate decreases continuously. This is mainly because higher phosphate concentrations overcome the mass transfer resistance at the interface between the aqueous phase and the solid, resulting in higher adsorption capacity.

FIG. 4 is an isotherm fit of the adsorption equilibrium data, the results of which are shown in Table 1. As can be seen from Table 1, Al is compared with Langmuir and Freundlich adsorption isothermal models₁₃-Bent、H⁺-Al₁₃The coefficient of the fitting model of the nips for adsorbing phosphate by Bent is higher, namely 0.994 and 0.997, and the Root Mean Square Error (RMSE) is smaller, which shows that the model of the nips for adsorbing isothermal can be very goodGood description of Al₁₃-Bent、H⁺-Al₁₃Isothermal adsorption behavior of Bent on phosphate. The non-uniformity coefficient ms in the Sips isotherm equation was 0.3484, 0.3920, respectively, indicating that phosphate adsorption by the loaded bentonite is not a simple monolayer uniform surface adsorption, which corresponds to the lower coefficient of certainty of the Langmuir fit. Al (Al)₁₃-Bent and H⁺-Al₁₃The maximum equilibrium adsorption capacity of the Bent fit of the bits to the phosphate is 36.18mg g^-1、32.17mg·g^-1It can be seen that the acid activation cannot effectively improve the phosphate adsorption capacity of the supported bentonite, which is probably because the main mechanism of phosphate adsorption of the supported bentonite is ligand exchange between phosphate and hydroxyl functional groups, and the acid activation changes the partial pore structure of the bentonite, improves the specific surface area of the bentonite, but has little influence on the aluminum hydroxyl loading capacity.

TABLE 1 adsorption isotherm model fitting parameters

Kinetics of adsorption

To analyze the phosphate adsorption kinetics of the loaded bentonite, the adsorption process was fitted using pseudo first order kinetics, pseudo second order kinetics and an Elovich model (fig. 5), and the fitting results are shown in table 2. As can be seen from Table 2, Al₁₃-Bent、H⁺-Al₁₃In the fitting of Bent to phosphate adsorption kinetics, the coefficient of the pseudo second order kinetics fitting is 0.986 and 0.991 respectively, meanwhile, the actual equilibrium adsorption capacity of the pseudo second order kinetics is closer to the calculated equilibrium adsorption capacity, the root mean square error RMSE is smaller, and the result shows that Al is in a condition of low temperature and high humidity₁₃-Bent、 H⁺-Al₁₃The adsorption of phosphate by Bent follows pseudo second order kinetics. The fitting coefficient of the Elovich model is 0.999, RMSE<0.2, which shows that the Elovich model can well fit the kinetic process, therefore, the adsorption process is mainly chemical adsorption. The adsorption rate relation of the initial adsorption process, namely H, can be roughly inferred from the magnitude of the initial adsorption rate constant alpha of an Elovich equation⁺-Al₁₃-Bent>Al₁₃Bent, which indicates that acid activation can increase the initial adsorption rate of phosphate by the loaded bentonite. This is probably due to the smaller volume of H in the acid activation process⁺And cations among bentonite layers are replaced, so that layered lattices are cracked, pore channels are more smooth, and phosphate can enter the layers more quickly to be combined with adsorption sites.

TABLE 2 kinetic fitting parameters

Note: q. q.s_e(exp)、q_e(cal) actual equilibrium adsorption amount and calculated equilibrium adsorption amount, respectively.

Influence of pH on the adsorption

FIG. 6 shows the effect of pH on phosphate adsorption by the supported bentonite, and it can be seen from the graph that the adsorption of phosphate by the two supported bentonites is greatly affected by pH, but Al₁₃-Bent and H⁺-Al₁₃-Bent is not very different. When pH is 3, Al₁₃Bent and H⁺-Al₁₃Maximum phosphate adsorption by Bent, when phosphate ions are predominantly H₂PO₄ ^-In the form of a supported OH on Al-OH functional groups on the surface of bentonite^-With H in solution₂PO₄ ^-Ligand exchange occurs to realize phosphorus adsorption, and the pH value of the solution is increased after the adsorption; when the pH is increased from 3 to 9, the adsorption capacity is gradually reduced, mainly because the deprotonation degree of the surface of the loaded bentonite is increased along with the increase of the pH, the negative potential of the surface is increased, and the phosphate is mainly existed in a form of H₂PO₄ ^-To HPO₄ ^2-Electrostatic repulsion enhanced, and OH^-The content is increased to compete with phosphate adsorption, so the adsorption amount of phosphate is reduced. And when pH is 1, Al₁₃Bent and H⁺-Al₁₃Bent is low in phosphate adsorption, probably because of the bentonite-loaded Al under the pH condition³⁺Dissolved out and phosphate is mainly H₃PO₄The form exists, and effective adsorption is difficult.

Step four: design of the response surface with Al₁₃Bent is used as adsorbing material, and the pH (X) is selected₁) Temperature (X)₂) Initial concentration (X)₃) 3 variables are used as influence factors, phosphate equilibrium adsorption capacity (Y) is used as a response value, an optimization test is designed according to a BBD principle, a response regression model is established, analysis of variance (ANOVA) is carried out on test data, interaction among the influence factors and influence on the response value are researched, pH, temperature and initial concentration of phosphate solution are selected according to results, and hydroxy aluminum loaded bentonite is added to remove phosphate. The method comprises the following specific steps:

adsorption reaction optimization analysis

Response surface analysis experiment Design and variance analysis are carried out by adopting experiment Design software Design-Expert 8.0, and the experiment Design is shown in table 3.

TABLE 3 analysis of response surface Experimental design and results

From table 3, the quadratic regression equation for the code form is as follows:

from the formula (10), it is understood that the influence of the 3 influencing factors on the phosphate adsorption amount is an interactive, rather than a simple linear relationship. The significance of the quadratic model was assessed by analysis of variance (ANOVA), the results of which are shown in table 4. As can be seen from Table 4, the model F value was 75.52, P<0.0001, indicating that regression model fitting is significant. And the correction decision coefficient of the model

Illustrating that about 98.98% of the response values can be interpreted by the model, the mismatching term P0.0796>0.05, the mismatching item is not significant, and the significance of the model is further illustrated. Coefficient of variation CV is 1.90%<10% Precision (Adeq Precision) 25.903>4, illustrating the better precision of the modelThe reliability is higher. For example, as shown in fig. 7, the slope of the straight line is close to 1, indicating that the model prediction result of the phosphate adsorption amount is highly consistent with the experiment result. In conclusion, the model can be used for predicting the experimental conditions of phosphate adsorption of the loaded bentonite.

TABLE 4 analysis of variance of response surface quadratic model

As can be seen from table 5, the F values of the 3 influencing factors are 108.57, 94.2 and 132.61 respectively, and the P values are all less than 0.0001, indicating that the influence of the 3 factor terms on the response values is significant; among the interaction terms, the interaction term of pH and temperature, the interaction term of pH and initial concentration significantly affected the response value (P < 0.05).

In order to intuitively understand the interaction among the factors and the influence on the response value, a three-dimensional response surface map is drawn according to a regression equation (fig. 8(a) -fig. 8 (c)). FIG. 8(a) shows the effect of the interaction between pH and initial concentration on the equilibrium adsorption amount at 30 ℃ and shows that the interaction between pH and initial concentration is significant, and when pH is 2 to 4, the initial concentration of phosphate is 80 to 120 mg.L^-1In this case, the amount of phosphate adsorbed increases with increasing initial concentration, and increases and then decreases with increasing pH. FIG. 8(b) shows the initial concentration of 100 mg.L^-1The influence of the interaction of the pH and the reaction temperature on the equilibrium adsorption amount is known from the figure, the interaction of the pH and the temperature is obvious, when the pH is 2-4 and the reaction temperature is 25-35 ℃, the adsorption amount of phosphate is increased along with the increase of the temperature, and is increased and then reduced along with the increase of the pH. FIG. 8(c) shows the effect of the interaction between the reaction temperature and the initial concentration on the equilibrium adsorption amount at pH 3, and it can be seen from the graph that the response curve has a small gradient and the contour line has a circular shape, indicating that the interaction between pH and the initial concentration is not significant and does not substantially affect each other. ByIt can be seen that appropriate lowering of the solution pH, raising the reaction temperature and initial concentration can effectively increase its phosphate adsorption capacity.

According to Design of Design Expert software, the optimal adsorption condition of phosphate is predicted, and the pH, the temperature and the initial concentration of the phosphate solution are respectively set to be 2.51, 35 ℃ and 120 mg.L^-1. The experimental result shows that the equilibrium adsorption capacity of the phosphate is 21.18 mg.g^-1Predicted equilibrium adsorption capacity with phosphate of 20.54mg g^-1The relative deviation of the model is only 1.53%, which shows that the model can better predict the actual value and has certain guiding significance in practical application.

In conclusion, 1) XRD and SEM-EDS characterization results show that metal ions among bentonite layers can be dissolved out through acid activation, so that pore channels are dredged, the interlayer spacing is enlarged, the interlayer spacing of the bentonite layers is further increased after loading, irregular Al-OH clusters appear on the surfaces, the aluminum element proportion is increased, and the result shows that aluminum hydroxide ions are successfully inserted into the bentonite layers.

2) Sips adsorption isothermal equation can be well fitted with Al₁₃-Bent、H⁺-Al₁₃-adsorption process of Bent on phosphate, fitting maximum adsorption capacity of 36.18, 32.17mg g^-1It can be seen that acid activation does not effectively increase Al₁₃-phosphate adsorption capacity of Bent. Al (Al)₁₃-Bent and H⁺-Al₁₃The adsorption kinetics of Bent to phosphate conforms to the pseudo-second order kinetics, Elovich kinetics equation, chemisorption being the main rate-limiting step, and the pseudo-second order rate parameter k₂And Elovich initial rate constant α, acid activation can increase Al₁₃Initial adsorption rate of phosphate by Bent.

3) The Box-Behnken design experiment result shows that the regression model can be used for optimizing the experiment conditions (F is 75.52, P is less than 0.0001), and the reaction temperature, the pH value and the initial concentration of phosphate obviously influence the phosphate adsorption amount in the process of adsorbing phosphate by the loaded bentonite; among the interaction items, the interaction item of pH and temperature, and the interaction item of pH and initial concentration significantly affected the response value (P < 0.05). The prediction experiment shows that the relative deviation between the experimental measured value and the model predicted value is only 1.53%, and the regression model can better predict the actual value and provide certain guidance for practical application.

4) In a system for adsorbing phosphate by using the bentonite, the adsorption capacity of the bentonite on the phosphate can be effectively improved by properly reducing the pH value of the solution and increasing the reaction temperature and the initial concentration.

The scope of the present invention is not limited to the above embodiments, and any modifications, equivalent substitutions, improvements and the like which can be made by those skilled in the art within the spirit and principle of the inventive concept should be included in the scope of the present invention.

Claims (10)

1. A preparation method of hydroxyl aluminum loaded bentonite is characterized by comprising the following steps:

the method comprises the following steps: acidifying the bentonite with a sulfuric acid solution to obtain acid activated bentonite;

step two: adding acid activated bentonite into a pillaring agent, stirring, aging at constant temperature, and centrifuging to wash the product until no Cl is generated^-Drying, grinding and sieving to obtain the hydroxyl aluminum loaded bentonite.

2. The method for preparing aluminum hydroxy-supported bentonite according to claim 1, wherein the mass concentration of the sulfuric acid solution is 20%.

3. The method for preparing aluminum hydroxide-supported bentonite according to claim 2, wherein the ratio of the sulfuric acid solution to the bentonite is 1g of bentonite and 10mL of sulfuric acid solution.

4. The method of claim 3, wherein the acid-activated bentonite added to the pillaring agent is selected from the group consisting of Al, Ca, Al, and mixtures thereof³⁺10 mmol/g of soil^-1And (4) weighing.

5. The method for preparing the aluminum hydroxide-supported bentonite according to claim 4, wherein the preparation method of the pillaring agent comprises the following steps: 0.6 mol/L^-1Dropping NaOH solution into 1.0mol·L^-1AlCl₃Solution of the components in such a way that the molar ratio OH is^-/Al³⁺And (5) aging at constant temperature, namely 2.4.

6. The method of claim 5, wherein the drying temperature is 90 ℃.

7. The method of claim 6, wherein the mesh number of the sieve is 150.

8. The process for preparing a bentonite supported by aluminum hydroxide according to any of claims 1 to 7, wherein the acid-activated bentonite is added to the pillaring agent separately, stirred at 60 ℃ for 5 hours, and aged at constant temperature for 12 hours.

9. A phosphate removal process based on activated supported bentonite, comprising: the method comprises the steps of establishing a response regression model by using the hydroxyl aluminum loaded bentonite as an adsorption material, the pH, the temperature and the initial concentration of phosphate as influence factors and the equilibrium adsorption quantity of phosphate as a response value, carrying out response surface design and variance analysis, selecting the pH, the temperature and the initial concentration of phosphate solution according to results, and adding the hydroxyl aluminum loaded bentonite to remove the phosphate.

10. The activated bentonite-based phosphate removal process of claim 9, wherein the phosphate adsorption is calculated as follows:

in the formula: q. q.s_eThe equilibrium adsorption amount of the soil sample to phosphate is mg.g^-1；C₀And C_eRespectively the initial concentration and the equilibrium concentration of phosphate in the solution, mg.L^-1(ii) a m is the mass of the hydroxyl aluminum load bentonite, g; v is the volume of phosphate solution, mL.

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