CN108654580A - A kind of order mesoporous zirconium phosphate material, preparation method and its application in waste water - Google Patents

Abstract

The invention discloses a kind of order mesoporous zirconium phosphate material, preparation method and its applications in waste water.Using template as the structure directing agent of synthesising mesoporous basic zirconium phosphate so that alcohol solvent slowly volatilizees, and one-step synthesis forms the basic zirconium phosphate with three dimensions；The present invention's uses the zirconium phosphate material of meso-hole structure for adsorbent, simultaneously, chemisorption is carried out to the uranyl ion in solution under the conditions of isothermal vibration, the uranyl ion in waste water is rapidly complexed with the phosphonic functional groups of material surface, more efficient absorption uranyl ion；The order mesoporous zirconium phosphate material preparation method of the present invention is simply inexpensive, can handle the demand of nuclear power station Uranium in Waste Water, and treated, and sample is also easy to recycle, and has preferable application market.

Description

A kind of ordered mesoporous zirconium phosphate material, its preparation method and its application in wastewater

technical field

The invention is applied to the environmental protection field of treating radioactive uranium wastewater, and in particular relates to the preparation of mesoporous zirconium phosphate and its use for adsorption and separation of radioactive uranyl ions in wastewater.

Background technique

Nuclear energy is a newly developed and utilized energy in modern times. As a relatively clean energy source, nuclear energy has the advantage of high efficiency. Similarly, the radioactive waste produced during the mining and smelting of uranium ore and other mines containing radionuclides not only pollutes the environment on which human beings depend, but also causes waste of resources due to the radionuclides discharged during the production process.

At present, the main mechanism for treating radioactive wastewater is to enrich the radioactive substances in low- and medium-level radioactive wastewater into high-level radioactive wastewater, and the rest of the wastewater reaches the discharge standard for further treatment. The main methods for extracting uranium from wastewater include adsorption, flotation, solvent extraction separation, biological treatment, ion exchange, chemical precipitation, superconducting magnetic separation, etc. The adsorption method is one of the most researched methods at present, and the research focus of the extraction of uranium by the adsorption method is to research and develop new uranium adsorption materials.

Adsorption treatment of radioactive wastewater will not bring secondary pollutants to the water body, and the precipitate formed by the adsorbent and radionuclides can be easily separated from the water body. And through the desorption process, the radionuclides in the waste liquid can be reused as resources. The problems faced by the separation and enrichment of uranyl ions in wastewater are: (1) The material preparation process is complicated, the cost is high, and it is not easy to scale up production, which is not conducive to practical application. (2) Physical adsorption of general adsorbents such as diatomite, zeolite, activated carbon, and bentonite has low adsorption capacity. (Document 1: S.Kumar, V.A.Loganathan, R.B.Gupta, M.O.Barnett, Anassessment of U(VI) removal from groundwater using biochar produced from hydrothermal carbonization, J.Environ.Manage.2011, 92:2504–2512) (3) in There is no specific selective adsorption in the presence of multiple ions, literature 2 (Xia Liu, Jiaxing Li, Xiangxue Wang, Changlun Chen, Xiangke Wang. High performance of phosphate-functionalized graphene oxide for the selective adsorption of U(VI) from acidic solution. Journal of Nuclear Materials.2015, 466:56-64) studied that phosphoric acid-functionalized materials adsorb uranyl ions in wastewater and achieved better results, and the adsorption capacity is much higher than that of non-phosphoric acid-functionalized materials.

Contents of the invention

Aiming at the problems existing in the existing adsorbent materials for treating uranium-containing wastewater, the present invention provides an ordered mesoporous zirconium phosphate material. The adsorbent mesoporous zirconium phosphate prepared by the present invention has ordered nanopore channels and a relatively high specific surface area , selective adsorption, stable structure, easy recycling and environmental friendliness. In order to achieve the above advantages, the technical scheme adopted in this experiment is as follows:

An ordered mesoporous zirconium phosphate material, prepared by sol-gel method and solvent evaporation self-assembly (EISA), using a template as a structure-directing agent for synthesizing mesoporous zirconium phosphate, so that ethanol solvent volatilizes slowly , one-step synthesis to form zirconium phosphate with three-dimensional space. Include the following steps:

(1) The template agent F127 was dissolved in anhydrous ethanol solvent as the directing agent.

(2) Add ZroCl ₂ .8H ₂ O and PO(OCH ₃ ) ₃ as zirconium source and phosphorus source respectively to (1), and magnetically stir for 4-10 hours.

(3) Pour the solution of (2) into a petri dish, place it at 333K for 48 hours, and then place it at 383K for 24 hours to obtain the precursor xerogel.

(4) The precursor xerogel was placed in a muffle furnace for calcination at 773K, and the obtained material was named MZrP-773K.

Preferably, the molar ratio of F127:(P+Zr) in step (1) is 0.01.

Preferably, the molar ratio of ZroCl ₂ .8H ₂ O to PO(OCH ₃ ) ₃ in step (2) is 0.75.

Further, in step (3), when the solution in step (2) is poured into the petri dish, it is covered with a layer of plastic wrap with small holes to prevent the absolute ethanol solvent from volatilizing too quickly.

Further optimization, the heating rate of calcination in step (4) is 1K/min, and calcination at 773K for 4h.

Compared with the prior art, the present invention has the advantages of:

(1) The adsorbent of the present invention is a zirconium phosphate material with a mesoporous structure, and the ordered mesoporous structure provides a larger adsorption reaction contact area.

(2) The material chemically adsorbs uranyl ions in the solution under constant temperature and shaking conditions, and the uranyl ions in the wastewater quickly complex with the phosphoric acid functional groups on the surface of the material instead of general physical adsorption, so that the adsorption is more efficient Uranyl ion.

(3) The material itself is an acid-resistant material. Under strong acid conditions, the mesoporous zirconium phosphate that adsorbs uranyl ions can quickly desorb uranyl ions, and the adsorption material can be recycled, thereby achieving the separation and enrichment of uranyl ions in wastewater. the goal of.

(4) The preparation method of the material is simple and low-cost, and it can handle the demand for uranium in nuclear power plant wastewater, and the treated samples are easy to reuse, so it has a good application market.

Description of drawings

Fig. 1 is the XRD figure of ordered mesoporous zirconium phosphate material of the present invention;

Fig. 2 is the SEM of ordered mesoporous zirconium phosphate material of the present invention;

Fig. 3 is the FTIR figure of ordered mesoporous zirconium phosphate material of the present invention;

Fig. 4 is the N of ordered mesoporous zirconium phosphate material of the present invention Adsorption _- desorption isotherm curve;

Fig. 5 is the XPS spectrogram of ordered mesoporous zirconium phosphate material of the present invention;

Fig. 6 is a diagram showing the adsorption effect of ordered mesoporous zirconium phosphate materials on uranyl ions at different initial concentrations in the embodiment;

Fig. 7 is a graph showing the adsorption effect of ordered mesoporous zirconium phosphate materials on uranyl ions at different pHs in the embodiment;

Fig. 8 is a diagram of the adsorption effect of ordered mesoporous zirconium phosphate materials on uranyl ions at different adsorption times in the embodiment;

Fig. 9 is a graph showing the adsorption effect of ordered mesoporous zirconium phosphate materials on uranyl ions in the presence of various metal ions in the embodiment.

Detailed ways

(1) Preparation of ordered mesoporous zirconium phosphate materials

The invention provides an application of a mesoporous structure material in the field of uranium-containing wastewater treatment, and it is found that it has strong adsorption performance for uranyl ions in the wastewater and can be used for many times.

(2) Material performance characterization test

The materials were characterized by SEM, TEM, XRD, FTIR, BET and XPS.

(3) Material adsorption performance test

The adsorption properties of adsorption materials for uranyl ions under different initial concentrations, pH, contact time and the presence of various metal ions, as well as the adsorption kinetic model of materials.

Example

Preparation of Mesoporous Zirconium Phosphate Materials

(1) Using sol-gel method and solvent evaporation self-assembly (EISA), add 1.2g of template agent F127 into 13ml of absolute ethanol solvent, heat in an oil bath, control the temperature at 303K, and stir magnetically until clarified.

(2) Weigh 1.6125g (5mmol) of zirconium source ZroCl ₂ .8H ₂ O and add it to the solution in step (1), stir until completely dissolved; add 0.5253g (3.75mmol) of phosphorus source PO(OCH ₃ ) ₃ was dissolved in 2ml of absolute ethanol, slowly added dropwise to the above solution, where P/Zr=0.5-1.0, and magnetically stirred for 6h.

(3) Pour the solution of (2) into a petri dish, cover a layer of plastic wrap on the petri dish and leave a small hole, place it in an oven at 333K for 48 hours, and then place it at 383K for 24 hours to obtain a dry gel that is mesoporous Precursor of zirconium phosphate.

(4) The above-mentioned precursor xerogel was calcined in a muffle furnace at a heating rate of 1 °C/min, calcined at 773K for 4 hours, and then naturally cooled to 303K.

Material Performance Testing

1 X-ray diffraction analysis (XRD)

The X-ray diffraction analysis of the adsorbent mesoporous zirconium phosphate of the embodiment of the present invention is as shown in Figure 1, adopts the D8Advance type X-ray diffractometer (XRD) that German Bruker Company produces to carry out phase analysis to sample, and test condition is: graphite single Chromatic device, Cu-Kα radiation, radiation wavelength λ=0.15418nm, tube voltage 40kV, tube current 40mA, scanning angle range 2θ=0.6-10. In Figure 1, the four curves a, b, c, and d indicate that the molar ratio of P/Zr during material preparation is 0.75, 1, 0.5, 0.25, respectively. It can be clearly seen from Figure 1 that scanning in the small angle range, All four curves at 2θ=0.80-0.9° have strong diffraction peaks, which are (100) crystal planes, but it can be clearly found that with the increase of the molar ratio of P/Zr, the diffraction peaks at this place are gradually enhanced; When P/Zr=0.75, the intensity of diffraction peak is the strongest; when P/Zr>0.75, the intensity of diffraction peak decreases obviously. And the diffraction peak at 2θ=1.55-1.65° is the (110) crystal plane. In Figure 1, a and b curves have a weaker diffraction peak at this position, while c and d curves do not have a diffraction peak at this position . Therefore, it is obvious from the XRD characterization that the structure of the synthesized mesoporous zirconium phosphate material is more uniform and orderly when the material is prepared with P/Zr=0.75, and P/Zr=0.75 is the best molar ratio for material preparation. The formula calculates that the pore diameter of the synthetic material with the molar ratio P/Zr=0.75 is 5.673nm, and the structure of the material is further illustrated by scanning electron microscopy (SEM) and N2 adsorption and desorption tests on the material.

2 Scanning electron microscope (SEM) morphology analysis

Scanning electron microscope and transmission electron microscope morphology analysis As shown in Figure 2, the morphology of the prepared samples was characterized using a Quant 250FEG (FEI) scanning electron microscope with an accelerating voltage of 30kV. Figure 2 is the scanning electron microscope image of the material mesoporous zirconium phosphate material. It can be seen from the figure that the surface of the material is smooth, the incision is flat, and the block structure is magnified by 5500 times to about 2um. Combined with the analysis of XRD characterization results, the material belongs to a three-dimensional order The bulk structure of nanopores.

3 Fourier transform infrared spectroscopy (FT-IR)

The Fourier transform infrared spectrometer was analyzed using a Nicoletis 10 Fourier transform infrared spectrometer produced by Thermo Fisher Scientific, USA. The FT-IR spectrum of the material is shown in Figure 3. Compared with the calcined material, the absorption band at 1630cm-1 is attributed to the O-H bending vibration of asymmetric water molecules; The absorption band belongs to the unsaturated C-H stretching vibration absorption peak in the template agent F127, which disappears after calcination at 773K, indicating that high-temperature calcination can completely remove the template and residual solvent; and the absorption band at 1000-1200cm-1 corresponds to the asymmetric P-O stretching vibration peak; the absorption band of 1640cm-1 is attributed to the stretching vibration peak and bending vibration peak of P-O. Adsorption process; the absorption band is at 960cm-1, the symmetrical stretching vibration of P-OH in phosphate belongs to the peak in phosphate, and disappears at 960cm-1, and the bending vibration absorption peak of phosphate appears at 600cm-1 after calcination 1, indicating that phosphorus exists in the form of PO in the calcined material.

4 specific surface area analysis (BET)

Fig. 4 is the N ₂ adsorption-desorption isotherm curves of CoMn ₂ O ₄ and CoMn ₂ O ₄ /rGO according to the examples of the present invention, which are measured by ASAP 2020 physical adsorption instrument produced by Micromeritics Company of the United States. The adsorption-desorption isotherms of the prepared mesoporous zirconium phosphate materials belong to the typical type IV isotherms, resulting in hysteresis and hysteresis loops, indicating that both materials have pore structures. The specific surface area calculated according to the BET adsorption isotherm equation and BJH model is 217.6157m ² g ^-1 , and the pore diameter is 5.8859nm. The specific surface area of the mesoporous zirconium phosphate material of the present invention is larger than that of the non-nanostructured materials reported in previous literatures. This provides a larger specific surface area and more active sites, which is beneficial to the adsorption of uranyl ions during the reaction.

5 XPS test

In order to further prove that uranyl ions are adsorbed on the surface of the mesoporous zirconium phosphate material, the full XPS spectrum of the material was obtained using a PHIQUANTERA II instrument produced by Japan Vacuum. The full XPS spectrum of the mesoporous zirconium phosphate material is shown in Figure 5. It can be seen from the figure that the material contains four elements, which are zirconium (Zr), oxygen (O), phosphorus (P) and carbon (C ), but after the material is adsorbed, a strong characteristic peak U4f of uranium appears in the XPS spectrum at 392eV and 381eV, which indicates that uranium (U) in the wastewater is indeed adsorbed on the surface of the material.

The application of adsorption performance of materials

Figure 6 shows the effect of different initial concentrations of uranyl ions on the adsorption. The mesoporous zirconium phosphate material is used as an adsorbent to adsorb uranyl ions in wastewater. The adsorption reaction is carried out in a constant temperature shaking box, the temperature is controlled at 298K, and the shaking rate is 180r/min. Take 6 groups of uranium-containing solutions with a pH of 4.5 but different initial concentrations (10mg/L, 40mg/L, 70mg/L, 100mg/L, 130mg/L, 160mg/L) containing 50mL of uranium solutions, and then add 0.01g of medium Porous zirconium phosphate was shaken at constant temperature for 24 hours, and the adsorption capacity and removal rate of uranyl ions in each group of mesoporous zirconium phosphate were measured. The results are shown in Figure 6. As the initial concentration increases, the adsorption capacity of mesoporous zirconium phosphate to uranyl ions is getting higher and higher, from 11 mg/g to 114 mg/g, but the removal rate of uranyl ions is getting lower and higher. The lower it is, it drops from 37% to about 25%, so it can be seen from the figure that when the initial concentration is 100mg/L, the adsorption capacity and removal rate of the adsorbent for uranyl ions are high, which is the optimal initial concentration.

Figure 7 shows the effect of different pH adsorption solutions on the adsorption performance. The mesoporous zirconium phosphate material is used as an adsorbent to adsorb uranyl ions in wastewater. The adsorption reaction is carried out in a constant temperature shaking box, the temperature is controlled at 298K, and the shaking rate is 180r/min. Take 50ml of uranium-containing adsorption solutions with 8 groups of different pH (pH=3,4,4.5,5,5.5,6,6.5,7) but the initial concentration is 100mg/L, then add 0.01g of mesoporous zirconium phosphate respectively, After shaking for 24 hours, the adsorption capacity of mesoporous zirconium phosphate on uranyl ions was measured. The results are shown in Figure 7. When pH=3-6.5, the adsorption capacity of mesoporous zirconium phosphate increases continuously with the increase of pH. When pH>6.5, the adsorption capacity of mesoporous zirconium phosphate decreases, but when pH> When the pH is 5.5, the uranyl ions in the adsorption solution will react with the OH- in the solution to form a light yellow precipitate, so choose pH = 5.5 as the optimal pH.

Figure 8 shows the effect of different contact reaction times on the adsorption performance. The mesoporous zirconium phosphate material is used as an adsorbent to adsorb uranyl ions in wastewater. The adsorption reaction is carried out in a constant temperature shaking box, the temperature is controlled at 298K, and the shaking rate is 180r/min. Take 50ml of adsorption solution with pH=5.5 and initial concentration of 100mg/L, add 0.01g of mesoporous zirconium phosphate, shake at constant temperature, take 9 different contact reaction times T (T=5min, 10min, 20min, 30min, 1h, 2h , 4h, 6h, 16h) of the adsorption solution, and measured the amount of adsorption of uranyl ions by mesoporous zirconium phosphate in each group. The results are shown in Figure 8. When T is less than 6h, the adsorption amount of mesoporous zirconium phosphate increases continuously with the increase of contact reaction time. When T is greater than or equal to 6h, the adsorption amount of mesoporous zirconium phosphate material to uranyl ions tends to be flat, so the best contact reaction time of mesoporous zirconium phosphate material to uranyl ions is 6h, and then fitting the obtained data, the maximum adsorption capacity is 298.37mg/g.

Figure 9 shows the effect of the adsorption solution containing various metal ions on the adsorption performance. The mesoporous zirconium phosphate material is used as an adsorbent to adsorb uranyl ions in wastewater. The adsorption reaction is carried out in a constant temperature shaking box, the temperature is controlled at 298K, and the shaking rate is 180r/min. Take 50ml of adsorption solution with pH=5.5 and initial concentration of 100mg/L, which contains 100mg/L of various metal ions (Na+, K+, Mg2+, Mn2+, Co2+, Ni2+, Sr2+), add 0.01g of mesoporous zirconium phosphate , after shaking at constant temperature for 24 hours, the adsorption capacity of mesoporous zirconium phosphate on uranyl ions was measured. The results are shown in Figure 9. In the presence of various metal ions, the adsorption capacity of mesoporous zirconium phosphate to uranyl ions is still as high as 290 mg/g, accounting for about 85.37% of the total adsorption capacity. There is selective adsorption.

Mesoporous zirconium phosphate materials were successfully synthesized by sol-gel method and solvent evaporation self-assembly (EISA), and applied to adsorb uranyl ions in wastewater. Add mesoporous zirconium phosphate to the adsorption solution with pH=5.5 and initial concentration of 100mg/L, and place it in a 298K constant temperature shaking box at a shaking rate of 180r/min for 6h. The adsorption capacity of this adsorption material for uranyl ions is as high as 298.37mg /g. This is due to the large specific surface area of mesoporous zirconium phosphate, which increases the active sites for adsorption and promotes the complexation of phosphoric acid functional groups on the surface of the material with uranyl ions, thus indicating that the mesoporous zirconium phosphate prepared by this method can quickly and efficiently separate waste The uranyl ion is a good adsorbent.

Claims (9)

1. a kind of order mesoporous zirconium phosphate material, which is characterized in that the material preparation is using template as synthesising mesoporous phosphoric acid The structure directing agent of zirconium so that alcohol solvent slowly volatilizees, and one-step synthesis forms the basic zirconium phosphate with three dimensions；Including following Step：

(1) it is that directed agents are dissolved in anhydrous ethanol solvent by template F127；

(2) with ZroCl₂.8H₂O and PO (OCH₃)₃Respectively as zirconium source and phosphorus source, it is added in (1), magnetic agitation 4-10h；

(3) solution of (2) is poured into culture dish, places at least 48h in 333K ± 5K, is then placed at least in 383K ± 5K For 24 hours, presoma xerogel is obtained；

(4) it is placed under 773K and calcines under presoma xerogel, obtain the basic zirconium phosphate MZrP-773K with three dimensions.

2. order mesoporous zirconium phosphate material according to claim 1, which is characterized in that in step (1) in step (2) F127:(P+Zr) molar ratio is 0.01.

3. order mesoporous zirconium phosphate material according to claim 1, which is characterized in that ZroCl in step (2)₂.8H₂O and PO(OCH₃)₃Molar ratio be 0.5-1.0.

4. order mesoporous zirconium phosphate material according to claim 1, which is characterized in that in step (3), step (2) it is molten Liquid covers one layer of preservative film when pouring into culture dish, and carries aperture, prevents anhydrous ethanol solvent volatilization too fast.

5. order mesoporous zirconium phosphate material according to claim 1, which is characterized in that the heating speed calcined in step (4) Rate is 1K/min, and 4h is calcined under temperature 773K.

6. a kind of preparation method based on the order mesoporous zirconium phosphate materials of claim 1-5.

7. a kind of application process based on any Mesoporous zirconium phosphate materials of claim 1-5, which is characterized in that the application process Specifically, using Mesoporous zirconium phosphate material as adsorbent, the uranyl ion in waste water is adsorbed；Actual conditions are, in isothermal vibration Under the conditions of, adsorbent Mesoporous zirconium phosphate is added in the solution containing uranyl ion t=298K, rotating speed=180r/min, absorption Time is 0.05-24h；It is desorbed again after absorption.

8. the application process of Mesoporous zirconium phosphate material according to claim 7, which is characterized in that the uranyl ion is molten The initial concentration of liquid is 10-200mg/L, and the initial pH of adsorbent solution is 3-7.

9. a kind of order mesoporous zirconium phosphate material according to claim 7, which is characterized in that desorption process is：It will absorption Mesoporous zirconium phosphate material afterwards, which is added in the nitric acid of a concentration of 3mol/L, shakes 4h, centrifuges, and washes 3 times, 343K drying.