CN111744454A - A kind of preparation method of composite phosphorus removal adsorbent lanthanum oxycarbonate loaded montmorillonite - Google Patents

Abstract

The invention discloses a preparation method of a composite phosphorus removal adsorbent lanthanum oxycarbonate loaded montmorillonite, and relates to a preparation method of a composite phosphorus removal adsorbent. The invention aims to solve the technical problems that the existing phosphorus removal adsorbent has more preparation processes, small adsorption capacity, difficult recycling of powdery adsorbent, high treatment cost and easy secondary sludge generation. The method comprises the following steps: dissolving montmorillonite in strong acid solution, and stirring uniformly; repeatedly washing acid-modified montmorillonite with deionized water to neutrality, and performing suction filtration; drying the filter cake to obtain modified montmorillonite; weighing a certain amount of lanthanum nitrate and glycine according to a molar ratio, adding a small amount of deionized water into a beaker, and uniformly stirring; adding a certain amount of modified montmorillonite, adding a small amount of deionized water, and continuously stirring to uniformly mix; transferring the mixture into a drying oven and drying. And transferring the precursor into a muffle furnace, and calcining. And cooling to room temperature, and uniformly grinding to obtain the composite phosphorus removal adsorbent lanthanum oxycarbonate loaded montmorillonite which can be used in the field of phosphorus-containing wastewater treatment.

Description

A kind of preparation method of composite phosphorus removal adsorbent lanthanum oxycarbonate loaded montmorillonite

technical field

The invention relates to a preparation method of a composite phosphorus removal adsorbent.

Background technique

Phosphorus is an indispensable key nutrient element for the growth of aquatic plants, but too much phosphorus will lead to eutrophication of water bodies, which is the main cause of water pollution, eutrophication of lakes and red tides in bays. Therefore, the key to solving these problems is to Remove excess PO ₄ ^3- in the water body. At present, how to improve the efficiency of phosphorus removal has become a hot and difficult research topic.

Different phosphorus removal technologies should be used for different wastewater sources. Commonly used water phosphorus removal technologies include chemical method, biological method, membrane separation method, ion exchange method and adsorption method. The adsorption phosphorus removal technology has the characteristics of small footprint, low energy consumption, low cost and high efficiency. It can adsorb PO ₄ ^3- in a wide concentration range, and the adsorbent can be recovered by desorption treatment, which is helpful to realize the recycling of resources. use. Therefore, adsorption method is widely used in wastewater pretreatment, advanced treatment and emergency treatment.

The rare earth element lanthanum is an environmentally friendly, non-toxic and harmless substance with strong binding force to soluble phosphate. Lanthanum can form stable and water-insoluble LaPO ₄ with PO ₄ ^3- in a molar ratio of 1:1, and the lanthanum-containing adsorbent has the advantages of high adsorption capacity and regeneration, and is often used as a phosphorus removal adsorbent. However, the powdered adsorbent will sink to the bottom of the water body during the phosphorus removal process, making it difficult to recycle. This shortcoming greatly increases the treatment cost of phosphorus-containing wastewater and easily causes sludge pollution.

Montmorillonite is a versatile material, which is widely used in the field of adsorption due to its good ion exchange, strong adsorption capacity, economical benefits, large storage capacity and no pollution. Under the action of interlayer and solvent, montmorillonite can be exfoliated and dispersed into thin single crystals, thereby improving its adsorption capacity and improving adsorption effect. However, the adsorption capacity of montmorillonite is still small, which cannot meet the treatment of wastewater containing high concentration of phosphorus.

In view of the above problems, the present invention loads La ₂ O ₂ CO ₃ on the modified montmorillonite to form a La ₂ O ₂ CO ₃ @Mt composite adsorbent, which effectively improves the phosphorus removal efficiency and powder utilization rate.

SUMMARY OF THE INVENTION

The invention aims to solve the technical problem of low removal rate of PO ₄ ^3- by the existing phosphorus removal adsorbent, and provides a preparation method of the phosphorus removal composite adsorbent La ₂ O ₂ CO ₃ @Mt.

The preparation method of the composite phosphorus removal adsorbent lanthanum oxycarbonate loaded montmorillonite of the present invention is carried out according to the following steps:

S1: Preparation of modified montmorillonite: dissolve the montmorillonite in a strong acid solution, stir for 1-3 hours; repeatedly wash the acid-modified montmorillonite with deionized water to neutrality, and filter with suction; transfer the filter cake Dry in an oven at 100-120°C for 5-7 hours to obtain modified montmorillonite;

S2: Preparation of precursor: Weigh a certain amount of lanthanum nitrate and glycine into a beaker, add a small amount of deionized water, and stir evenly; add a certain amount of modified montmorillonite, add a small amount of deionized water, and heat to a 65°C, stirring speed is 200-500r/min, stirring for 30min; transfer to an oven and dry at 120-180°C for 10-12h to obtain the precursor;

S3: Preparation of composite adsorbent: transfer the precursor into a muffle furnace, calcining; after cooling to room temperature, grind evenly to obtain a composite phosphorus removal adsorbent lanthanum oxycarbonate supported montmorillonite, denoted as La ₂ O ₂ CO ₃ @Mt Sorbent.

Preferably, in the step S1, the acid is sulfuric acid or nitric acid, pH=1;

Preferably, in the step S1, the solid-to-liquid ratio of the montmorillonite to the acid with pH=1 is 1:(9-11);

Preferably, in the step S2, the molar ratio n (lanthanum nitrate):n (glycine)=1:2;

Preferably, in the step S2, the mass ratio of lanthanum nitrate to the modified montmorillonite is (0.3-0.6):1;

Preferably, in the step S3, the calcination temperature in the muffle furnace is 440-460° C., and the calcination time is 2-3 hours.

The La ₂ O ₂ CO ₃ @Mt adsorbent of the present invention is prepared by the glycine-nitrate method, and the La ₂ O ₂ CO ₃ is tightly supported on the surface of the montmorillonite by calcination, which is easy to recover. The La ₂ O ₂ CO ₃ @Mt adsorbent greatly increased the specific surface area, enhanced its adsorption capacity for PO ₄ ^3- , and improved the phosphorus removal efficiency.

The La ₂ O ₂ CO ₃ @Mt adsorbent prepared by the invention adsorbs PO ₄ ^3- , and the removal rate of PO ₄ ^3- reaches 98.1%-99.5%, which can be used in the field of phosphorus-containing wastewater treatment.

Description of drawings

Fig. 1 is the X-ray diffraction analysis diagram of modified montmorillonite and La ₂ O ₂ CO ₃ @Mt in Example 1;

Fig. 2 is the scanning electron microscope photo of modified montmorillonite in embodiment 1;

Fig. 3 is the scanning electron microscope photo that modified montmorillonite enlarges in embodiment 1;

Fig. 4 is the scanning electron microscope photograph of La ₂ O ₂ CO ₃ @Mt in Example 1;

Fig. 5 is the scanning electron microscope photograph magnified by La ₂ O ₂ CO ₃ @Mt in Example 1;

6 is a graph showing the change of the removal rate of La ₂ O ₂ CO ₃ @Mt to PO ₄ ^3- with adsorption time in Example 2;

Figure 7 is a graph showing the change of the removal rate of La ₂ O ₂ CO ₃ @Mt to PO ₄ ^3- with pH in Example 3;

Figure 8 is a graph showing the change of the removal rate of La ₂ O ₂ CO ₃ @Mt to PO ₄ ^3- with substrate concentration in Example 4;

FIG. 9 is a graph showing the change of the removal rate of La ₂ O ₂ CO ₃ @Mt to PO ₄ ^3- with the dosage of adsorbent in Example 5. FIG.

Detailed ways

The beneficial effects of the present invention are verified with the following examples.

Embodiment 1: the preparation method of the composite phosphorus removal adsorbent lanthanum oxycarbonate loaded montmorillonite of the present embodiment is carried out according to the following steps:

S1: Put 10g of montmorillonite in 100mL of pH=1 sulfuric acid solution, stir with a constant temperature magnetic stirrer at room temperature for 2h, after the reaction is completed, filter and wash the modified montmorillonite until neutral, and place it in a drying oven Inside, it was baked at 110 °C for 6 h and ground to obtain modified montmorillonite (Mt) for experiment.

S2: According to the molar ratio n (lanthanum nitrate):n (glycine)=1:2, weigh a certain amount of lanthanum nitrate and glycine into a beaker, add a small amount of deionized water, and stir magnetically for 30min; The mass ratio of delithiation is 0.5:1, a certain amount of modified montmorillonite is added, and the magnetic stirring is continued to make it evenly mixed, then transferred to an oven at 180 ° C for 12 hours, and ground to obtain the precursor;

S3: The precursor is calcined in a muffle furnace at 450 °C for 2 hours, cooled and ground to obtain a composite phosphorus removal adsorbent lanthanum oxycarbonate supported montmorillonite, that is, a phosphorus removal composite adsorbent La ₂ O ₂ CO ₃ @Mt.

The XRD patterns of the modified montmorillonite and La ₂ O ₂ CO ₃ @Mt obtained in Example 1 are shown in FIG. 1 . It can be seen from Figure 1 that the XRD peaks of the modified montmorillonite show the shape of the steamed bread peak, indicating that the montmorillonite exists in an amorphous state. The XRD pattern of La ₂ O ₂ CO ₃ @Mt showed a series of sharp diffraction peaks, indicating that the sample was completely crystallized after calcination. Compared with the standard card PDF#20-0452, it was found that the produced substance was CaAl ₂ Si ₂ O ₈ ·H ₂ O is the main component of montmorillonite. In addition, the diffraction peaks at _11.080 °, _22.266 °, _25.831 °, 30.368° and 44.420° correspond to (002), (004), (101), (103) and (110) crystal planes, indicating that La ₂ O ₂ CO ₃ has been successfully loaded on the surface of montmorillonite, indicating that La ₂ O ₂ CO ₃ @Mt was successfully prepared.

The SEM photos of the modified montmorillonite in step S1 of Example 1 are shown in Figures 2 and 3. It can be seen that the particle size of the modified montmorillonite is about 70 μm, the surface is uneven, and some areas are relatively smooth, while In another part of the region, a large number of particles with a size of about 1 μm are distributed. The scanning electron microscope photos of La ₂ O ₂ CO ₃ @Mt obtained in step 3 are shown in Figures 4 and 5. Combined with XRD analysis, it can be seen that after high temperature calcination, the internal structure of montmorillonite is destroyed, and it is transformed from amorphous to crystalline The particle size and morphology of the material have undergone great changes, from the original morphology to fragments with uneven shape and holes, and the particle sizes are different, and the larger fragment size is 30 μm.

Example 2:

The La ₂ O ₂ CO ₃ @Mt obtained in step S3 is tested for adsorption performance, and the steps are as follows: Weigh 50mg La ₂ O ₂ CO ₃ @Mt, add 50mg/L PO ₄ ^3- solution, and measure PO 3 at room temperature. ₄ ^3- solution is adsorbed, and the removal effect is characterized by the removal rate R, which is calculated according to the following formula:

R(%)=(c ₀ -c)/c ₀ ×100%

Among them, c ₀ represents the concentration of PO ₄ ^3- before adsorption, and c represents the concentration of PO ₄ ^3- after adsorption. The results are shown in Figure 6. It can be seen from Figure 6 that the adsorption of PO ₄ ^3- by La ₂ O ₂ CO ₃ @Mt reaches equilibrium in about 120 minutes, and the removal rate can reach 98.1%-99.5%.

Example 3:

Adjust 50mg/L KH ₂ PO ₄ solution to pH=1～7 with HCl or NaOH, and then add 50mg/LLa ₂ O ₂ CO ₃ @Mt respectively to carry out adsorption experiments. The operation steps are the same as those in Example 2.

The results are shown in Figure 7. It can be seen from Figure 7 that when the pH of the solution is in the range of 1 to 7, the pH has little effect on the adsorption effect of La ₂ O ₂ CO ₃ @Mt, and La ₂ O ₂ CO ₃ @ The removal rate of Mt to PO ₄ ^3- was maintained above 98%.

Example 4:

Weigh 50mg La ₂ O ₂ CO ₃ @Mt and add it to 50mg/L, 100mg/L, 150mg/L, 200mg/L and 250mg/L PO ₄ ^3- solutions for adsorption experiments, operation steps and examples 2 are the same.

The results are shown in Figure 8. It can be seen from Figure 8 that the removal rate of PO ₄ ^3- tends to decrease as the substrate concentration increases. When the substrate concentration is 50 mg/L to 250 mg/L, the removal rate of rate decreased from 98.63% to 93.88%.

Example 5:

12.5mg, 25mg, 50mg, 75mg, 100mg, 125mg and 150mg La ₂ O ₂ CO ₃ @Mt were weighed and added to 50 mg/L PO ₄ ^3- solution for adsorption experiments. The operation steps were the same as those in Example 2.

The results are shown in Figure 9. It can be seen from Figure 9 that when the dosage of La ₂ O ₂ CO ₃ @Mt adsorbent is 0.25g/L, the removal rate is 94.26%, and the dosage of adsorbent increases to At 1.0g/L, the removal rate reached 99.50%, the dosage of adsorbent continued to increase to 3.0g/L, and the removal rate of adsorbent to PO ₄ ^3- remained basically unchanged.

The above description of the disclosed embodiments enables any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (6)

1. A preparation method of a composite phosphorus removal adsorbent lanthanum oxycarbonate loaded montmorillonite is characterized by comprising the following steps:

s1: preparation of modified montmorillonite: dissolving montmorillonite in a strong acid solution, and stirring for 1-3 h; repeatedly washing acid-modified montmorillonite with deionized water to neutrality, and performing suction filtration; transferring the filter cake to an oven, and drying at 100-120 ℃ for 5-7 h to obtain modified montmorillonite;

s2: preparing a precursor: weighing a certain amount of lanthanum nitrate and glycine in a beaker, adding a small amount of deionized water, and uniformly stirring; adding a certain amount of modified montmorillonite, adding a small amount of deionized water, heating to 65 ℃ under magnetic stirring, and stirring at the speed of 200-500r/min for 30 min; transferring the mixture to an oven to be dried for 10-12 h at the temperature of 120-180 ℃;

s3: preparing a composite adsorbent: transferring the precursor into a muffle furnace for calcining; cooling to room temperature, and grinding uniformly to obtain the composite phosphorus removal adsorbent lanthanum oxycarbonate loaded montmorillonite marked as La₂O₂CO₃@ Mt adsorbent.

2. The method for preparing the composite phosphorus removal adsorbent lanthanum oxycarbonate loaded montmorillonite according to claim 1, wherein in step S1, the acid is sulfuric acid or nitric acid, and the pH is 1.

3. The preparation method of the composite phosphorus removal adsorbent lanthanum oxycarbonate loaded montmorillonite according to claim 1, characterized in that in step S1, the solid-liquid mass ratio of montmorillonite to acid with pH of 1 is 1 (9-11).

4. The composite phosphorus removal adsorbent La as claimed in claim 1₂O₂CO₃The preparation method of @ Mt is characterized in that in step S2, the molar ratio of lanthanum nitrate to glycine is 1: 2.

5. The preparation method of the composite phosphorus removal adsorbent lanthanum oxycarbonate loaded montmorillonite according to claim 1, characterized in that in step S2, the mass ratio of lanthanum nitrate to montmorillonite is (0.3-0.6): 1.

6. The preparation method of the composite phosphorus removal adsorbent lanthanum oxycarbonate loaded montmorillonite according to claim 1, characterized in that in step S3, the calcination temperature in a muffle furnace is 440-460 ℃, and the calcination time is 2-3 h.

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