Method for purifying chloride ions in ammonium nitrate solution and use thereof

Abstract

The application relates to the field of ammonium nitrate solution preparation, and particularly discloses a method for purifying chlorides in an ammonium nitrate solution and application thereof. The method for purifying chlorides in the ammonium nitrate solution comprises the following steps: after source water is treated by reverse osmosis to remove impurities, a chloride adsorbent is added to obtain desalted water; ammonia gas is reacted with oxygen to generate nitrogen oxides, the nitrogen oxides are reacted with the desalted water to generate dilute nitric acid; after liquid ammonia is gasified, ammonia gas is obtained, the ammonia gas is subjected to a neutralization reaction with the dilute nitric acid, and high-concentration ammonium nitrate solution is obtained after evaporation; and the chloride adsorbent is sodium alginate-coated activated carbon loaded with silver ions. According to the application, the chloride adsorbent is added into source water used for preparing the ammonium nitrate solution, so that the concentration of chlorides in the source water is reduced, and the chlorides in the prepared ammonium nitrate solution are removed.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of ammonium nitrate solution preparation, and more particularly to a method for purifying chloride ions in an ammonium nitrate solution and application thereof. BACKGROUND

[0002] N2O has important medical uses, and its anesthetic and analgesic effects are remarkable, and is widely used as an anesthetic for surgery and dentistry. N2O is generally prepared by thermal decomposition of an ammonium nitrate solution, which is stable at room temperature, but due to the presence of chloride ions in the source water during production, the prepared ammonium nitrate solution contains residual chloride ions, which can lower the decomposition temperature and accelerate the decomposition of the ammonium nitrate solution, thereby causing safety hazards such as decomposition explosion. Therefore, it is particularly important to reduce the concentration of chloride ions in the ammonium nitrate solution for the safe preparation of N2O. SUMMARY

[0003] In order to develop a method for removing chloride ions from water and thereby reduce the concentration of chloride ions in the ammonium nitrate solution, the present application provides a method for purifying chloride ions in an ammonium nitrate solution and application thereof.

[0004] In a first aspect, the present application provides a method for purifying chloride ions in an ammonium nitrate solution, which adopts the following technical solution:

[0005] A method for purifying chloride ions in an ammonium nitrate solution, comprising the following steps:

[0006] S1, after the source water is removed by reverse osmosis, a chloride ion adsorbent is added to obtain desalinated water; ammonia gas is reacted with oxygen to generate nitrogen oxides, and the nitrogen oxides are reacted with the desalinated water to generate dilute nitric acid;

[0007] S2, liquid ammonia is gasified to generate ammonia gas, and the ammonia gas is subjected to a neutralization reaction with the dilute nitric acid, and after evaporation, a high-concentration ammonium nitrate solution is obtained;

[0008] The chloride ion adsorbent is sodium alginate-coated activated carbon loaded with silver ions.

[0009] By adopting the above technical solution, the chloride ion adsorbent is added to the source water used in the preparation of the ammonium nitrate solution, thereby reducing the concentration of chloride ions in the source water and further reducing the concentration of chloride ions in the prepared ammonium nitrate solution, effectively avoiding the decomposition temperature reduction, decomposition speed acceleration, and even decomposition explosion hazards during the preparation of N2O by thermal decomposition of the ammonium nitrate solution.

[0010] The chloride ion adsorbent of the present application is sodium alginate-coated activated carbon loaded with silver ions, which adsorbs chloride ions in source water through the synergistic effect of chemical reaction between silver ions and chloride ions and physical adsorption of activated carbon. Specifically, activated carbon has abundant pore structure and large specific surface area, providing a good carrier platform for the loading of silver ions. After silver ions are loaded on the surface of activated carbon, chloride ions in water will undergo ion exchange and precipitation reaction with silver ions to generate silver chloride precipitate, thereby removing chloride ions from water. At the same time, the physical adsorption of activated carbon itself can also adsorb and retain part of the chloride ions and reaction products, and the two cooperate with each other to achieve efficient removal of chloride ions in water. In addition, sodium alginate is coated on the surface of activated carbon due to its excellent adhesion, and the good hydrophilicity of sodium alginate endows the activated carbon loaded with silver ions with excellent water dispersibility, thereby further improving the adsorption effect of the chloride ion adsorbent.

[0011] Preferably, the preparation method of the chloride ion adsorbent comprises the following steps:

[0012] (1) The activated carbon is subjected to plasma treatment under a nitrogen-containing gas to obtain an aminated activated carbon; the aminated activated carbon is added to water and stirred to obtain a suspension; silver nitrate solution is added to ammonia water until the initially generated precipitate is dissolved to form a silver-ammonia solution; the suspension is added to the silver-ammonia solution and reacted at 40-60°C for 30-60 min, and then filtered, washed and dried to obtain an activated carbon loaded with silver ions adsorbent;

[0013] (2) The activated carbon loaded with silver ions adsorbent is dispersed in deionized water to form a suspension, then sodium alginate is added to the suspension and stirred to obtain a mixture, and the mixture is added to a calcium salt solution for crosslinking reaction, and then spray dried to obtain sodium alginate-coated activated carbon loaded with silver ions.

[0014] By adopting the above technical solution, the amino groups generated on the surface of the activated carbon after plasma treatment form coordination bonds with silver ions, enhancing the stability and loading amount of silver; at the same time, the porous structure of activated carbon provides physical retention space for silver, reducing agglomeration; the strong coordination effect (forming AgCl) between silver ions and chloride ions is the main driving force for adsorption, while the surface charge of the aminated activated carbon can reduce the interference of other anions, improving the adsorption selectivity, and the electronic conjugation effect between silver and amino further enhances the binding energy of chloride ions; in addition, the improved surface polarity and hydrophilicity of plasma treatment promote the dispersion of the material in water and the contact efficiency with the silver-ammonia solution, ultimately realizing efficient and stable adsorption of chloride ions in water, with high removal rate, fast adsorption rate and cycle stability.

[0015] Preferably, in step (1), the pH of the suspension is adjusted to 8-10.

[0016] By adopting the technical scheme, through adjusting the pH of the suspension, the amino part is protonated to form a positively charged -NH3 + , the unprotonated amino (-NH2) is combined with silver ions to form a coordination bond, which not only enhances the loading stability and loading capacity of silver, but also enables the loaded silver ions to be combined with chloride ions through coordination precipitation, and through the synergistic mechanism of "electrostatic adsorption pre-enrichment + coordination deep fixation", the adsorption effect on chloride ions is significantly improved.

[0017] Preferably, in step (1), the power during the plasma treatment is 100-150 W, the time is 10-15 min, and the gas flow is 100-150 sccm.

[0018] By adopting the technical scheme, when the power is too low, the degree of amination is insufficient, and the number of electrostatic adsorption sites is less than the number of coordination sites; and when the power is too high, excessive etching of the activated carbon causes the collapse of the pore channel, and high-energy particles may cause the amino group to dehydrogenate to form an imine, thereby reducing the protonation capacity.

[0019] When the treatment time is too short, the amination is insufficient, and the electrostatic adsorption and silver ion coordination sites are insufficient, and when the treatment time is too long, the amino group on the surface of the activated carbon is excessively polymerized to form a long chain, which blocks the micropores and reduces the adsorption effect on chloride ions, and the protonation efficiency is reduced due to the steric hindrance of the long-chain amino group.

[0020] When the gas flow is too low, the concentration of active particles is insufficient, and the reaction rate is slow; and when the gas flow is too high, the gas quickly flows through the plasma zone, and the active particles are carried out before being fully reacted, thereby reducing the amination efficiency, and the high-speed airflow may physically wash the surface of the activated carbon, thereby damaging the pore structure.

[0021] In summary, by adjusting the above parameters, the present application can realize the synergy of "highly active amino group - ordered pore structure - appropriate charge density" on the surface of the aminated activated carbon, and finally strengthen the "electrostatic pre-enrichment - coordination deep fixation" dual adsorption mechanism for chloride ions.

[0022] Preferably, in step (1), the mass-to-volume ratio of the aminated activated carbon to the silver nitrate solution is (1-10) g:1 L.

[0023] By adopting the technical scheme, the mass-to-volume ratio of the aminated activated carbon to the silver nitrate solution is optimized, which can match the silver ion loading capacity with the amino active site, so that the silver ions are uniformly loaded in the form of single atoms or small molecular clusters, which not only forms Ag + -Cl - coordination bond through coordination, and promotes the protonation of the amino group to form -NH3 + , and the Cl -Finally, through the synergistic mechanism of "coordination fixation-electrostatic pre-enrichment", the adsorption effect of chloride ions is improved.

[0024] Preferably, in step (2), the mass ratio of silver ion loaded activated carbon to sodium alginate is 1: (0.4-0.6).

[0025] By adopting the above technical solution, the proportion can not only enhance the mechanical strength of the composite material through the polysaccharide network of sodium alginate, but also further improve the loading stability and loading capacity of silver ions by utilizing the coordination action of carboxyl in sodium alginate molecules and silver ions (similar to the coordination mechanism of amino groups). At the same time, the hydrophilic network of sodium alginate can promote the diffusion of chloride ions to the surface of activated carbon, and the electrostatic field formed by the negatively charged carboxyl and protonated amino groups can synergize with the coordination precipitation of silver ions and chloride ions. Under the multiple mechanisms of "network support-site synergy-diffusion enhancement", the balance between adsorption capacity and material practicability is achieved, and the proportion can avoid the problems of pore blockage or uneven dispersion of silver ions caused by excessive sodium alginate, taking into account the optimization of cost and performance.

[0026] Preferably, in step (2), the mass ratio of sodium alginate to calcium salt is 1: (1-3).

[0027] By adopting the above technical solution, optimizing the mass ratio of sodium alginate to calcium salt can promote the formation of a "network support-site synergy-diffusion enhancement" mechanism by Ca 2+ The "egg box structure" formed by the moderate crosslinking of sodium alginate carboxyl not only guarantees the mechanical strength and pore diffusion performance of the material, but also forms an electrostatic field with the hydrophilic network of sodium alginate and the amino groups on the surface of activated carbon, promoting the enrichment of chloride ions. At the same time, the sodium alginate gel layer can protect the active sites of silver ions, improve the adsorption stability and regeneration efficiency, and achieve the balance between mechanical properties and adsorption effect.

[0028] Preferably, the calcium salt is calcium chloride, calcium iodide, calcium dihydrogen phosphate, or calcium nitrate, and further preferably is calcium chloride.

[0029] By adopting the above technical solution, Ca 2+ It can quickly form an "egg box" crosslinking structure with guluronic acid units on the sodium alginate chain, and the crosslinking reaction efficiency is relatively high. Moreover, the pH adaptability of calcium chloride solution is wide, and it can stably function in different acid-base systems. At the same time, it is low in price, easy to obtain, has extremely low toxicity as a necessary electrolyte of living organisms, and has good biocompatibility. In addition, by adjusting the concentration of calcium chloride, the hardness and network pore size of the gel can be precisely controlled, which is simple to operate and controllable in performance.

[0030] Preferably, in step (2), the crosslinking reaction temperature is 20-50℃, and the time is 30-90min.

[0031] By adopting the technical scheme, the temperature and time during cross-linking affect the material performance through regulating the ion diffusion rate and cross-linking degree; specifically, the temperature rise can accelerate the Ca 2+ The cross-linking rate with the carboxyl group of sodium alginate can promote the uniform formation of the "egg box structure" in a suitable range, but if the temperature is too high, it can cause thermal degradation of sodium alginate, destroying the network stability; the cross-linking time needs to match the temperature condition, and short time can easily lead to insufficient cross-linking and poor mechanical strength, and long time can cause local over-cross-linking, reducing the pore size and hindering ion diffusion.

[0032] In summary, by optimizing the temperature and time during cross-linking, an elastic network with suitable porosity can be formed, considering the mass transfer efficiency and structural strength, and optimizing the chloride ion adsorption effect.

[0033] In a second aspect, the application provides a method for preparing N2O, adopting the following technical scheme:

[0034] A method for preparing N2O, adopting the above-mentioned thermal decomposition of ammonium nitrate solution.

[0035] By adopting the above technical scheme, the application reduces the chloride ion concentration in the ammonium nitrate solution, so that the ammonium nitrate solution can be safely produced under thermal decomposition conditions to produce N2O, avoiding the occurrence of explosion and other hazards.

[0036] In summary, the application has at least one of the following beneficial technical effects:

[0037] 1. The application uses sodium alginate-coated activated carbon loaded with silver ions as a chloride ion adsorbent, which adsorbs chloride ions in source water through the chemical reaction between silver ions and chloride ions and the physical adsorption of activated carbon, improving the removal rate of chloride ions in water, and thereby reducing the chloride ion concentration in the prepared ammonium nitrate solution;

[0038] 2. The application loads silver ions on the amino-activated carbon, and the loaded silver ions can form a precipitate with Cl - ; at the same time, by wrapping the activated carbon loaded with silver ion adsorbent in sodium alginate, the effective combination of the two is achieved, and the dispersibility of the chloride ion adsorbent in water is improved, further improving the adsorption effect of chloride ions;

[0039] 3. The application adjusts the pH of the suspension, and the amino group is protonated to form a positively charged -NH3 + ; the unprotonated amino group (-NH2) forms a coordination bond with silver ions, which not only enhances the loading stability and loading amount of silver, but also enables the loaded silver ions to combine with chloride ions through coordination precipitation, and through the synergistic mechanism of "electrostatic adsorption pre-enrichment + coordination deep fixation", the adsorption effect of chloride ions is significantly improved. DETAILED DESCRIPTION

[0040] The application is further described in detail below in connection with the preparation examples and examples.

[0041] The raw materials of the examples and comparative examples of the present application are all ordinary commercial products unless otherwise specified.

[0042] Preparation Example 1

[0043] The present preparation example discloses a preparation method of a chloride ion adsorbent, which is specifically as follows:

[0044] (1) Put the coconut shell activated carbon with a particle size of 20-60 mesh into a radio frequency plasma device, adjust the flow rate of ammonia gas to 100 sccm, and perform plasma induction treatment at a power of 150 W for 10 min to obtain aminated activated carbon; add 0.1 g of the aminated activated carbon into 20 ml of deionized water and adjust the pH to 8 by ammonia water to obtain a suspension; add ammonia water dropwise into a 0.1 mol / L silver nitrate solution until the initially formed precipitate dissolves to form a silver-ammonia solution; add the above suspension into 100 ml of the silver-ammonia solution, and react at a temperature of 40℃ for 60 min to obtain a product which is filtered, washed with deionized water for 3 times, and dried at 30℃ to obtain an activated carbon loaded silver ion adsorbent;

[0045] (2) Add the above 10 g of activated carbon loaded silver ion adsorbent into 100 ml of a 4 wt% sodium alginate solution, stir to dissolve to obtain a mixed solution, and add the mixed solution dropwise into 100 ml of a 4 wt% calcium chloride solution to react at 20℃ for 90 min, and then spray dry to obtain a sodium alginate coated activated carbon loaded silver ion.

[0046] Preparation Example 2

[0047] The present preparation example is basically the same as Preparation Example 1, except that in step (1), the coconut shell activated carbon with a particle size of 20-60 mesh is placed in a radio frequency plasma device, the flow rate of ammonia gas is adjusted to 100 sccm, and plasma induction treatment is performed at a power of 150 W for 10 min to obtain aminated activated carbon; 0.1 g of the aminated activated carbon is added into 20 ml of deionized water and stirred uniformly to obtain a suspension by adjusting the pH to 9.5 with ammonia water; ammonia water is added dropwise into a 0.1 mol / L silver nitrate solution until the initially formed precipitate dissolves to form a silver-ammonia solution; the above suspension is added into 100 ml of the silver-ammonia solution, and the reaction is performed at a temperature of 40℃ for 60 min to obtain a product which is filtered, washed with deionized water for 3 times, and dried at 30℃ to obtain an activated carbon loaded silver ion adsorbent.

[0048] Preparation Example 3

[0049] The preparation example is basically the same as Preparation Example 1, except that in step (1), the particle size of the coconut shell activated carbon is 20-60 mesh, the flow rate of ammonia gas is adjusted to 100 sccm, and the plasma-induced treatment is carried out at a power of 150 W for 10 min to obtain aminated activated carbon; 0.1 g of the aminated activated carbon is added to 20 ml of deionized water and stirred uniformly by adjusting the pH to 10 with ammonia water to obtain a suspension; ammonia water is added dropwise to a 0.1 mol / L silver nitrate solution until the initially formed precipitate dissolves to form a silver ammine solution; the above suspension is added to 100 ml of the silver ammine solution, and the reaction is carried out at a temperature of 40°C for 60 min to obtain a product, which is filtered, washed with deionized water for 3 times, and dried at 30°C to obtain an activated carbon loaded silver ion adsorbent.

[0050] Preparation Example 4

[0051] The preparation example is basically the same as Preparation Example 2, except that in step (1), the particle size of the coconut shell activated carbon is 20-60 mesh, the flow rate of ammonia gas is adjusted to 120 sccm, and the plasma-induced treatment is carried out at a power of 130 W for 12 min to obtain aminated activated carbon; 0.1 g of the aminated activated carbon is added to 20 ml of deionized water and stirred uniformly by adjusting the pH to 9.5 with ammonia water to obtain a suspension; ammonia water is added dropwise to a 0.1 mol / L silver nitrate solution until the initially formed precipitate dissolves to form a silver ammine solution; the above suspension is added to 100 ml of the silver ammine solution, and the reaction is carried out at a temperature of 40°C for 60 min to obtain a product, which is filtered, washed with deionized water for 3 times, and dried at 30°C to obtain an activated carbon loaded silver ion adsorbent.

[0052] Preparation Example 5

[0053] The preparation example is basically the same as Preparation Example 2, except that in step (1), the particle size of the coconut shell activated carbon is 20-60 mesh, the flow rate of ammonia gas is adjusted to 150 sccm, and the plasma-induced treatment is carried out at a power of 100 W for 15 min to obtain aminated activated carbon; 0.1 g of the aminated activated carbon is added to 20 ml of deionized water and stirred uniformly by adjusting the pH to 9.5 with ammonia water to obtain a suspension; ammonia water is added dropwise to a 0.1 mol / L silver nitrate solution until the initially formed precipitate dissolves to form a silver ammine solution; the above suspension is added to 100 ml of the silver ammine solution, and the reaction is carried out at a temperature of 40°C for 60 min to obtain a product, which is filtered, washed with deionized water for 3 times, and dried at 30°C to obtain an activated carbon loaded silver ion adsorbent.

[0054] Preparation Example 6

[0055] The preparation example is basically the same as preparation example 4, except that in step (1), the particle size of the coconut shell activated carbon is 20-60 mesh, the flow rate of ammonia gas is adjusted to 120 sccm, and the plasma-induced treatment is carried out at a power of 130 W for 12 min to obtain aminated activated carbon; 0.5 g of the aminated activated carbon is added to 20 ml of deionized water and stirred uniformly by adjusting the pH to 9.5 with ammonia water to obtain a suspension; ammonia water is added dropwise to a 0.1 mol / L silver nitrate solution until the initially formed precipitate dissolves to form a silver ammine solution; the above suspension is added to 100 ml of the silver ammine solution, and the reaction is carried out at a temperature of 40°C for 60 min to obtain a product, which is filtered, washed with deionized water for 3 times, and dried at 30°C to obtain an activated carbon-supported silver ion adsorbent.

[0056] Preparation example 7

[0057] The preparation example is basically the same as preparation example 4, except that in step (1), the particle size of the coconut shell activated carbon is 20-60 mesh, the flow rate of ammonia gas is adjusted to 120 sccm, and the plasma-induced treatment is carried out at a power of 130 W for 12 min to obtain aminated activated carbon; 1 g of the aminated activated carbon is added to 20 ml of deionized water and stirred uniformly by adjusting the pH to 9.5 with ammonia water to obtain a suspension; ammonia water is added dropwise to a 0.1 mol / L silver nitrate solution until the initially formed precipitate dissolves to form a silver ammine solution; the above suspension is added to 100 ml of the silver ammine solution, and the reaction is carried out at a temperature of 40°C for 60 min to obtain a product, which is filtered, washed with deionized water for 3 times, and dried at 30°C to obtain an activated carbon-supported silver ion adsorbent.

[0058] Preparation example 8

[0059] The preparation example is basically the same as preparation example 6, except that in step (2), the above 10 g of the activated carbon-supported silver ion adsorbent is added to 100 ml of a 5 wt% sodium alginate solution, stirred and dissolved to obtain a mixed solution, the mixed solution is added dropwise to 100 ml of a 4 wt% calcium chloride solution, and the reaction is carried out at 20°C for 90 min, and after spray drying, a sodium alginate-coated activated carbon-supported silver ion is obtained.

[0060] Preparation example 9

[0061] The preparation example is basically the same as preparation example 6, except that in step (2), the above 10 g of the activated carbon-supported silver ion adsorbent is added to 100 ml of a 6 wt% sodium alginate solution, stirred and dissolved to obtain a mixed solution, the mixed solution is added dropwise to 100 ml of a 4 wt% calcium chloride solution, and the reaction is carried out at 20°C for 90 min, and after spray drying, a sodium alginate-coated activated carbon-supported silver ion is obtained.

[0062] Preparation example 10

[0063] The present preparation example is basically the same as Preparation Example 8, except that in step (2), the above 10 g of activated carbon loaded silver ion adsorbent is added to 100 ml of 5 wt% sodium alginate solution, and the mixture is obtained by stirring and dissolving, and the mixture is added dropwise to 100 ml of 10 wt% calcium chloride solution at 20°C for 90 min, and after spray drying, sodium alginate coated activated carbon loaded silver ions are obtained.

[0064] Preparation Example 11

[0065] The present preparation example is basically the same as Preparation Example 8, except that in step (2), the above 10 g of activated carbon loaded silver ion adsorbent is added to 100 ml of 5 wt% sodium alginate solution, and the mixture is obtained by stirring and dissolving, and the mixture is added dropwise to 100 ml of 15 wt% calcium chloride solution at 20°C for 90 min, and after spray drying, sodium alginate coated activated carbon loaded silver ions are obtained.

[0066] Preparation Example 12

[0067] The present preparation example discloses a preparation method of amino-functionalized activated carbon, as follows:

[0068] The coconut shell activated carbon with a particle size of 20-60 mesh is placed in a radio frequency plasma device, the flow rate of ammonia gas is adjusted to 100 sccm, and plasma induction treatment is carried out at a power of 150 W for 10 min to obtain amino-functionalized activated carbon.

[0069] Preparation Example 13

[0070] The present preparation example discloses a preparation method of activated carbon loaded silver ion, as follows:

[0071] 0.1 g of coconut shell activated carbon with a particle size of 20-60 mesh is added to 20 ml of deionized water to obtain a suspension; ammonia water is added dropwise to a 0.1 mol / L silver nitrate solution until the initially formed precipitate dissolves to form a silver ammine solution; the above suspension is added to 100 ml of silver ammine solution, and the reaction is carried out at a temperature of 40°C for 60 min to obtain a product which is filtered, washed with deionized water for 3 times, and dried at 30°C to obtain an activated carbon loaded silver ion adsorbent.

[0072] Preparation Example 14

[0073] The present preparation example discloses a preparation method of chloride ion adsorbent, as follows:

[0074] (1) 0.1 g of coconut shell activated carbon with a particle size of 20-60 mesh was added to 20 ml of deionized water and stirred uniformly by adjusting the pH to 8 with ammonia water to obtain a suspension; ammonia water was added dropwise to a 0.1 mol / L silver nitrate solution until the initially formed precipitate dissolved to form a silver ammine solution; the above suspension was added to 100 ml of the silver ammine solution, and the resulting product was filtered after being reacted at a temperature of 40°C for 60 min, then washed with deionized water 3 times, and dried at 30°C to obtain an activated carbon loaded silver ion adsorbent;

[0075] (2) 10 g of the activated carbon loaded silver ion adsorbent was added to 100 ml of a 4 wt% sodium alginate solution, and stirred to dissolve to obtain a mixed solution; the mixed solution was added dropwise to 100 ml of a 4 wt% calcium chloride solution, and reacted at 20°C for 90 min, and then spray dried to obtain sodium alginate coated activated carbon loaded silver ions.

[0076] Preparation Example 15

[0077] The present preparation example discloses a preparation method of a chloride ion adsorbent, which is specifically as follows:

[0078] Coconut shell activated carbon with a particle size of 20-60 mesh was placed in a radio frequency plasma device, the flow rate of ammonia gas was adjusted to 100 sccm, and plasma induction treatment was performed at a power of 150 W for 10 min to obtain aminated activated carbon; 0.1 g of the aminated activated carbon was added to 20 ml of deionized water and stirred uniformly by adjusting the pH to 8 with ammonia water to obtain a suspension; ammonia water was added dropwise to a 0.1 mol / L silver nitrate solution until the initially formed precipitate dissolved to form a silver ammine solution; the above suspension was added to 100 ml of the silver ammine solution, and the resulting product was filtered after being reacted at a temperature of 40°C for 60 min, then washed with deionized water 3 times, and dried at 30°C to obtain an activated carbon loaded silver ion adsorbent.

[0079] Zeta potential test

[0080] The activated carbon loaded silver ions obtained in Preparation Examples 1-3 and 12 and the aminated activated carbon obtained in Preparation Example 13 were respectively taken 0.01 g, added to 0.1 L of deionized water, and ultrasonically dispersed for 10 min to obtain suspensions; 0.1 M HCl or 0.1 M NaOH solution was used to adjust the pH of each suspension to 2, 4, 6, 8, 10 and 12, and then the suspensions were left to stand for 10 min; a Zeta potential instrument was used to measure the Zeta potential at each pH point at 25°C, each sample was measured 3 times repeatedly, and the average value was taken, and the test results are recorded in Table 1.

[0081] Table 1: Performance test data table of Preparation Examples 1-3, 12 and 13

[0082]

[0083] Referring to Table 1, in combination with Preparation Examples 1, 12 and 13, it can be seen that the potential of Preparation Examples 1 and 12 decreases with the increase of pH, and there is a Zeta = 0 corresponding to the pKa characteristic of the amino group at pH between 8-10, while the change of Preparation Example 13 is not large with the increase of pH, indicating that the active carbon loaded silver ions prepared in Preparation Example 1 exist amino protonated NH3 + .

[0084] Referring to Table 1, in combination with Preparation Examples 1-3, it can be seen that the active carbon loaded silver ions prepared by adjusting the pH of the suspension to 8-10 in the present application all exist protonated NH3+, in particular, the higher the pH of the suspension, the less the amino protonated NH3 + exists in the active carbon loaded silver ions.

[0085] Example 1

[0086] The present embodiment discloses a method for purifying chloride ions in an ammonium nitrate solution, specifically comprising the following steps:

[0087] S1, pretreated liquid is obtained by treating source water through a reverse osmosis membrane, and the chloride ion adsorbent is put into the pretreated liquid according to a solid-liquid ratio of 1:1 (g:L) of the chloride ion adsorbent and the pretreated liquid, and desalted water is obtained after reaction and filtration;

[0088] S2, nitrogen oxides are generated by the reaction of ammonia gas and oxygen, and the nitrogen oxides react with the desalted water in the absorption tower to generate 58wt% dilute nitric acid; the neutralization reaction occurs between the 58wt% dilute nitric acid and the ammonia gas generated by the gasification of liquid ammonia, and evaporation and concentration are carried out to obtain the ammonium nitrate solution.

[0089] Among them, the chloride ion adsorbent is from Preparation Example 1, and the source water is from Lihe River water.

[0090] The present embodiment also discloses a preparation method of N2O, specifically: the above-mentioned ammonium nitrate solution is decomposed at 250°C to generate.

[0091] Example 2

[0092] The present embodiment is basically the same as Example 1, except that the chloride ion adsorbent is from Preparation Example 2.

[0093] Example 3

[0094] The present embodiment is basically the same as Example 1, except that the chloride ion adsorbent is from Preparation Example 3.

[0095] Example 4

[0096] The present embodiment is basically the same as Example 1, except that the chloride ion adsorbent is from Preparation Example 4.

[0097] Example 5

[0098] This example is essentially the same as Example 1 except that the chloride ion adsorbent is from Preparation Example 5.

[0099] Example 6

[0100] This example is essentially the same as Example 1 except that the chloride ion adsorbent is from Preparation Example 6.

[0101] Example 7

[0102] This example is essentially the same as Example 1 except that the chloride ion adsorbent is from Preparation Example 7.

[0103] Example 8

[0104] This example is essentially the same as Example 1 except that the chloride ion adsorbent is from Preparation Example 8.

[0105] Example 9

[0106] This example is essentially the same as Example 1 except that the chloride ion adsorbent is from Preparation Example 9.

[0107] Example 10

[0108] This example is essentially the same as Example 1 except that the chloride ion adsorbent is from Preparation Example 10.

[0109] Example 11

[0110] This example is essentially the same as Example 1 except that the chloride ion adsorbent is from Preparation Example 11.

[0111] Example 12

[0112] This example is essentially the same as Example 1 except that the chloride ion adsorbent is from Preparation Example 12.

[0113] Example 13

[0114] This example is essentially the same as Example 1 except that the chloride ion adsorbent is from Preparation Example 13.

[0115] Example 14

[0116] This example is essentially the same as Example 1 except that the chloride ion adsorbent is from Preparation Example 14.

[0117] Example 15

[0118] This example is essentially the same as Example 1 except that the chloride ion adsorbent is from Preparation Example 15.

[0119] Comparative Example 1

[0120] The embodiment discloses a preparation method of an ammonium nitrate solution, and specifically comprises the following steps:

[0121] S1, source water is treated by a reverse osmosis membrane to obtain desalted water;

[0122] S2, ammonia gas and oxygen gas are reacted to generate nitrogen oxides, and the nitrogen oxides are reacted with the desalted water in an absorption tower to generate 58wt% dilute nitric acid; the 58wt% dilute nitric acid is neutralized with ammonia gas generated by gasification of liquid ammonia, and is evaporated and concentrated to obtain the ammonium nitrate solution.

[0123] Performance detection test

[0124] The same mass of the ammonium nitrate solution and the source water obtained in each example and the comparative example is weighed, and the chloride ion concentration is determined according to the Silver Nitrate Titration Method for Determination of Chlorides in Water (GB11896), and the results are shown in Table 2.

[0125] Table 2: Performance detection data table of examples 1-15 and comparative example 1

[0126]

[0127] Referring to Table 2, in combination with Example 1 and Comparative Example 1, it can be seen that, in the present application, the source water used in the preparation of ammonium nitrate is purified by using sodium alginate-coated activated carbon loaded with silver ions as a chloride ion adsorbent, and the chloride ions in the source water are adsorbed through the synergistic effect of chemical reaction between silver ions and chloride ions and physical adsorption of activated carbon. At the same time, the sodium alginate is adsorbed to the surface of the activated carbon loaded with silver ions by taking advantage of the excellent adhesion of sodium alginate, and the excellent hydrophilicity of sodium alginate endows the activated carbon loaded with silver ions with excellent water dispersibility, thereby improving the adsorption of chloride ions in water and reducing the concentration of chloride ions in the source water, so that the concentration of chloride ions in the prepared ammonium nitrate solution is purified.

[0128] Referring to Table 2, in combination with Examples 1-3, it can be seen that, in the present application, by adjusting the pH of the suspension, the amino group is partially protonated to form a positively charged -NH3 + , which is combined with chloride ions through electrostatic adsorption, and the unprotonated amino group (-NH2) forms a coordination bond with silver ions, which not only enhances the stability and loading amount of silver, but also enables the loaded silver ions to be combined with chloride ions through coordination precipitation, and the two are combined through the synergistic mechanism of “electrostatic adsorption pre-enrichment + coordination deep fixation”, which significantly improves the adsorption effect of chloride ions.

[0129] Referring to Table 2, combined with Examples 1 and 14, it can be seen that after the activated carbon is treated by plasma, the amino groups generated on the surface of the activated carbon form coordination bonds with silver ions, enhancing the stability and loading amount of silver, and at the same time, the porous structure of the activated carbon provides physical entrapment space for silver, reducing agglomeration; the strong coordination effect (generating AgCl) between silver ions and chloride ions is the main driving force for adsorption, while the surface charge of the amino-functionalized activated carbon can reduce the interference of other anions, improving the adsorption selectivity, and the electronic conjugation effect between silver and amino further enhances the binding energy of chloride ions; in addition, the improved surface polarity and hydrophilicity of the plasma treatment promote the dispersion of the material in water and the contact efficiency with the silver-ammonia solution, ultimately achieving efficient and stable adsorption of chloride ions in water in cooperation.

[0130] Referring to Table 2, combined with Examples 1 and 15, it can be seen that the application utilizes the excellent adhesion of sodium alginate to coat the surface of activated carbon, and the good hydrophilicity of sodium alginate endows the activated carbon loaded with silver ions with excellent water dispersibility, thereby further improving the adsorption effect of the chloride ion adsorbent.

[0131] The specific embodiments are merely an explanation of the application, and are not a limitation of the application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the specification, as long as the modifications are within the scope of the claims of the application.

Claims

1. A method for purifying chloride ions in ammonium nitrate solution, characterized in that, Includes the following steps: S1, the source water is purified by reverse osmosis and then a chloride ion adsorbent is added to obtain demineralized water; ammonia is reacted with oxygen to generate nitrogen oxides, and the nitrogen oxides react with the demineralized water to generate dilute nitric acid; S2, liquid ammonia is vaporized to generate ammonia gas, which reacts with the dilute nitric acid in a neutralization reaction, and after evaporation, a high-concentration ammonium nitrate solution is obtained; The preparation method of the chloride ion adsorbent includes the following steps: (1) The activated carbon is subjected to plasma treatment under nitrogen gas to obtain aminated activated carbon; the aminated activated carbon is added to water and stirred to obtain a suspension; silver nitrate solution is added to ammonia water until the initially generated precipitate dissolves to form silver ammonia solution; the suspension is added to silver ammonia solution and reacted at 40-60℃ for 30-60 min; the mixture is then filtered, washed and dried to obtain activated carbon-supported silver ion adsorbent. (2) Activated carbon loaded with silver ions adsorbent is dispersed in deionized water to form a suspension, and then sodium alginate is added to the suspension and stirred to obtain a mixture. The mixture is added to a calcium salt solution for cross-linking reaction and spray-dried to obtain sodium alginate coated activated carbon loaded with silver ions.

2. The method for purifying chloride ions in ammonium nitrate solution according to claim 1, characterized in that, In step (1), the pH of the suspension is adjusted to 8-10.

3. The method for purifying chloride ions in ammonium nitrate solution according to claim 1, characterized in that, In step (1), the power of the plasma treatment is 100-150W, the time is 10-15min, and the gas flow rate is 100-150sccm.

4. The method for purifying chloride ions in ammonium nitrate solution according to claim 1, characterized in that, In step (1), the mass-to-volume ratio of the aminated activated carbon to the silver nitrate solution is (1-10) g: 1 L.

5. The method for purifying chloride ions in ammonium nitrate solution according to claim 1, characterized in that, In step (2), the mass ratio of the activated carbon loaded with silver ions to sodium alginate is 1:(0.4-0.6).

6. The method for purifying chloride ions in ammonium nitrate solution according to claim 1, characterized in that, In step (2), the mass ratio of sodium alginate to calcium salt is 1:(1-3).

7. The method for purifying chloride ions in ammonium nitrate solution according to claim 6, characterized in that, The calcium salt is calcium chloride, calcium iodide, calcium dihydrogen phosphate, or calcium nitrate.

8. The method for purifying chloride ions in ammonium nitrate solution according to claim 1, characterized in that, In step (2), the crosslinking reaction temperature is 20-50℃ and the time is 30-90min.

9. A method for preparing N2O, characterized in that, include: It is obtained by thermal decomposition of ammonium nitrate solution according to any one of claims 1-8.

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