Phosphorus nitride adsorbent with high-efficiency selectivity and its applications in removing uranium pollution and extracting uranium from seawater

Abstract

The invention discloses a phosphorus nitride adsorbent with high-efficiency selectivity, and its application thereof. The phosphorus nitride adsorbent has a mutually cross-linked hollow tubular structure. The adsorbent can have an adsorption capacity of 435.58 mg.Math.g.sup.−1 and 7.01 mg.Math.g.Math..sup.1 for spiked seawater and natural seawater with a uranium concentration of 350 ppb, and the adsorbent has a long service life, and can still maintain 91.14% of the initial adsorption capacity after 5 cycles of adsorption and desorption. Taking into account the advantages of a short material preparation cycle, a wide range of raw material sources, a low cost, an excellent adsorption performance, and long service life, the adsorbent can be used in technical fields such as uranium-containing wastewater treatment, uranium ore resource recovery, uranium extraction from seawater and the like.

Claims

1. An application of a phosphorus nitride adsorbent in treating uranium-containing wastewater, wherein the application comprises: adjusting a ratio of volume of the uranium-containing wastewater to be treated to mass of the adsorbent to 50 mL:0.010 g, and adjusting a pH to 2-9, adsorption temperature to 25-45° C., adsorption time to 2-180 min, and an oscillation speed to 370 rad/min.

2. The application according to claim 1, wherein the adsorption time is 60 min, the pH is adjusted to 4.0, and the adsorption temperature is 25° C.

3. The application according to claim 1, wherein the pH is adjusted with a 0.5 mol/L hydrochloric acid solution and a 1 mol/L sodium hydroxide solution.

4. An application of a phosphorus nitride adsorbent in extracting uranium from seawater, wherein the application comprises: adjusting a ratio of volume of the seawater to be treated to mass of the adsorbent to 50 L:0.01 g, adsorption temperature to 25-45° C., and adsorption time to 7-15 days, and controlling a flow rate of the seawater to 3.6 L/h.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a structural formula and adsorption mechanism of the phosphorus nitride adsorbent of the present invention, where a is a structural formula of the phosphorus nitride adsorbent, and b is an adsorption mechanism of the phosphorus nitride adsorbent;

(2) FIG. 2 is an infrared spectrum of the phosphorus nitride adsorbent of the present invention;

(3) FIG. 3 are scanning electron micrographs of phosphorus nitride adsorbents prepared under different reaction time conditions, where a is 3 h, b is 6 h, c is 9 h, and d is 12 h;

(4) FIG. 4 are scanning electron micrograph and a transmission electron micrograph of the phosphorus nitride adsorbent of the present invention, where a is a scanning electron micrograph, and b is a transmission electron micrograph;

(5) FIG. 5 is a graph showing an adsorption capacity of phosphorus nitride of the present invention as a function of time;

(6) FIG. 6 is an adsorption capacity comparison diagram of the present invention adsorbing various metals from actual seawater;

(7) FIG. 7 is a histogram showing the recycling utilization of the phosphorus nitride adsorbent of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

(8) In order to better illustrate the present invention, further description is given below with reference to practical examples. However, the actual content of the present invention is not limited to this, for example, where the feed ratio needs to be enlarged or reduced in equal proportions.

Embodiment 1

(9) 375 mg P.sub.3N.sub.3Cl.sub.6 is immersed in 30 mL methanol, and dispersed by ultrasound for 10 min until it is completely dissolved, and then 150 mg NaNH.sub.2 is added to the solution; then the suspension is transferred to a round-bottomed flask, and A is placed in a microwave reactor, with power adjusted to 500 W, heated to 160° C., and reacted for 9 h; the solid product is recovered by centrifugation, washed with water and ethanol, and freeze-dried overnight in a freeze dryer to finally obtain a phosphorus nitride material.

(10) An infrared spectrum of the phosphorus nitride material prepared in embodiment 1 is shown in FIG. 2. The broad absorption peak at 3420 cm.sup.−1 in the figure is attributed to the stretching vibration of —OH in the phosphoric acid group and indicates that the surface of the material has —NH.sub.2, the absorption peak at 1645 cm.sup.−1 is the characteristic peak of benzene ring, the peaks at 1220 cm.sup.−1 and 930 cm.sup.−1 belong to the characteristic peaks of P═N and P—N, respectively, and the peak at 1024 cm.sup.−1 belongs to phosphoric acid groups. The appearance of the above absorption peaks indicates that the phosphorus nitride material is successfully prepared, and the surface of the material is enriched with phosphoric acid groups and nitrogen-containing groups.

(11) Scanning electron micrographs of phosphorus nitride materials prepared at different reaction times under the conditions of this embodiment are shown in FIG. 3. From FIG. 3, we can clearly see that the structure of the material can be adjusted by the reaction time. As shown in FIG. 4, when the reaction time is 9 h, the prepared phosphorus nitride material presents hollow nanotubes with uniform sizes, which has the best adsorption effect.

Embodiment 2

(12) Phosphorus nitride materials are used to treat uranium-containing wastewater, and the specific method includes:

(13) First, a pH of 50 ml uranium-containing wastewater with a uranium concentration of 25 mg.Math.g.sup.−1 is adjusted to 4, and then a 10 mg phosphorus nitride material is put into the solution and vibrated for adsorption for 30 min.

(14) As shown in FIG. 5, the phosphorus nitride material can effectively remove 92.12% of uranium in wastewater, and its adsorption capacity reaches 230.29 mg.Math.g.sup.−1. The formula for calculating the adsorption capacity is shown in equation 1 below:
Q.sub.e=((C.sub.0−C.sub.t)V)/m  (1)

(15) Q.sub.e: adsorption capacity; C.sub.0: initial concentration; C.sub.t: equilibrium concentration; V: solution volume; m: adsorbent mass.

Embodiment 3

(16) Phosphorus nitride material is used to extract uranium from seawater, and the specific method includes:

(17) A 10 mg phosphorus nitride material is filled into a packed column, the flow rate of seawater is controlled to 3.6 L/h, and adsorption temperature is 25° C.

(18) As shown in FIG. 6, the phosphorus nitride material reaches a high adsorption capacity of 7.01 mg.Math.g.sup.−1 after 15 days.

Embodiment 4

(19) The specific method for the adsorption and desorption cycle life test of phosphorus nitride includes:

(20) First, a pH of 50 ml uranium-containing wastewater with a uranium concentration of 32 mg.Math.g.sup.−1 is adjusted to 4, then 10 mg phosphorus nitride is put into the solution, vibrated for adsorption for 30 min, the adsorbent is centrifuged for separation, and finally, it is put into the eluant prepared in advance containing sodium carbonate and hydrogen peroxide, and oscillated for 30 min, which can effectively elute uranium adsorbed on phosphorus nitride.

(21) As shown in FIG. 7, after repeated cycles for 5 times, the adsorption capacity can be maintained at 91.14% of the initial capacity and the elution rate can reach 96%.

(22) The above embodiments are only preferred embodiments of the present invention, and are not intended to limit implementations. The protection scope of the present invention shall be subject to the scope defined by the claims. On the basis of the above description, other different forms of changes or variations can also be made. The obvious changes or variations derived from this are still within the protection scope of the present invention.