Method for extracting rubidium based on fiber evaporative adsorber and space separation

Abstract

The present application belongs to the technical field of salt lake resource development and resource utilization, and particularly relates to a method for extracting rubidium based on fiber evaporation adsorber and space separation. The method uses commercial fibers with capillary transport capacity as base material, and in-situ grows copper potassium ferrocyanide and other selective adsorbents in the upper region of the fibers to construct a micro-scale cooperative system integrating capillary transport, interface evaporation, step-by-step crystallization and selective adsorption. The raw material liquid ascends along the fibers and is continuously concentrated, and the competitive ions with higher concentration and lower solubility are preferentially crystallized in the lower part of the fibers. Rubidium is relatively enriched and crystallized in the upper part of the fibers, and is selectively adsorbed by the upper adsorbent. Finally, the rubidium-containing solution is obtained by desorption. The present application can reduce the interference of Na + , K + and other competitive ions, simplify the solid-liquid separation process, and improve the separation selectivity and recovery efficiency of rubidium.

Description

Technical Field

[0001] This invention belongs to the field of salt lake resource development and resource utilization technology, specifically relating to a method for rubidium extraction based on fiber evaporator-adsorber synergistic spatial separation. It is a method for selectively extracting rubidium ions from saline or brine using a fiber evaporator (FE), and also relates to a fiber evaporator-adsorber suitable for this method. Background Technology

[0002] Rubidium resources have significant applications in high-tech fields such as specialty glass, pharmaceuticals, atomic clocks, and catalysis. Compared to the low rubidium content in solid ores, the high energy consumption and pollution associated with extraction processes, salt lake brines and other saline water systems offer abundant reserves and are relatively easy to access. Therefore, extracting rubidium from saline water has become an important direction for resource utilization.

[0003] Currently, the separation and extraction of rubidium mainly includes solvent extraction and adsorption methods. Solvent extraction typically requires the use of acids, alkalis, or organic solvents, which presents problems such as high cost, toxicity, and complex post-processing. Adsorption methods have advantages such as simple operation, regeneration, and high recovery rates; however, existing adsorbents such as Prussian blue analogues are mostly in powder form, making solid-liquid separation difficult, and in the presence of Na+... + K + When competing ions are present in large quantities, its selective adsorption performance decreases significantly.

[0004] To overcome the difficulty of recovering powdered adsorbents, existing technologies attempt to load adsorbents onto membrane materials, hydrogels, electrodes, or magnetic supports. While this improves the solid-liquid separation problem to some extent, it often introduces new problems such as complex preparation steps, increased costs, or higher equipment requirements. Meanwhile, the interference of competing ions has not been fundamentally resolved.

[0005] In recent years, evaporation crystallization technology, which achieves stepwise crystallization and spatial separation based on differences in the solubility and concentration of different salts, has attracted attention. If this physical separation mechanism can be organically coupled with the chemoselective adsorption of rubidium, it is expected to achieve efficient separation and recovery of rubidium in systems containing high concentrations of competing ions. However, how to construct an integrated system that combines capillary transport, interfacial evaporation, spatial stepwise crystallization, and top selective adsorption remains a key challenge for existing technologies.

[0006] There are two core problems in existing rubidium extraction technologies: First, although traditional powder adsorbents have a certain selectivity for rubidium, they are not suitable for high concentrations of Na+. + K + The adsorption performance is significantly reduced in the presence of competing ions, and solid-liquid separation is difficult after use; secondly, methods that rely solely on adsorption cannot simultaneously achieve high selectivity, simplified process, and operability of the device. Summary of the Invention

[0007] To address the aforementioned issues, this invention provides a method for extracting rubidium based on a fiber evaporator-adsorbent synergistic spatial separation. By integrating the fiber carrier, spatial separation process, and selective adsorption process into a unified design, a microscale synergistic system is constructed that combines continuous liquid transport, local evaporation and concentration, competitive ion preferential crystallization, and target ion localized adsorption.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A method for extracting rubidium based on a fiber evaporative adsorbent and its synergistic spatial separation involves using commercially available fibers with capillary transport capabilities as a substrate. A metal coordination adsorbent containing ferricyanide, such as KCuFC, is grown in situ in the upper region (20-30 cm above the fiber bottom) along the liquid migration direction to form a fiber evaporative adsorbent. In use, the lower end of the fiber evaporative adsorbent contacts the rubidium-containing feed solution, which is a binary solution containing sodium and rubidium or potassium and rubidium. Driven by capillary force, the sodium and rubidium or potassium and rubidium binary solution continuously rises along the fiber and undergoes interfacial evaporation under the influence of airflow and a temperature field. As the liquid continuously concentrates, the sodium, which has lower solubility and a higher initial concentration, is further extracted. + or K + Competing ions preferentially reach supersaturation and precipitate at lower positions on the fiber, while rubidium salts with higher solubility and lower initial concentrations gradually accumulate at higher positions (i.e., 20 to 30 cm), thus forming a spatially defined functional zone of "lower preferential crystallization separation zone - upper selective adsorption zone." The adsorbent in the upper region further selectively captures rubidium ions under conditions of significantly reduced competing ion concentration, achieving efficient separation and enrichment of rubidium. The specific steps are as follows: S1. Using a fiber material with capillary transport capacity as a substrate, an iron cyanide metal coordination adsorbent is grown in situ in the upper region of the fiber material to obtain a fiber evaporative adsorbent. S2. The lower part of the fiber evaporator is brought into contact with the rubidium-containing raw material liquid, and the raw material liquid is moved upward along the fiber under capillary action and continuously concentrated under evaporation. S3. By utilizing the differences in solubility and initial concentration of raw material solution between rubidium salt and competing ion salt, the competing ions are preferentially crystallized at lower positions of the fiber, while rubidium is relatively enriched and crystallized at higher positions of the fiber, thereby achieving spatial separation of rubidium and competing ions. S4. The rubidium ions in the enrichment region are selectively adsorbed by the adsorbent loaded at the higher position (upper region) of the fiber. S5. Desorb the adsorbed fiber evaporator to obtain a rubidium-containing desorbent.

[0009] The ferricyanide metal coordination adsorbent is at least one of potassium copper ferrocyanide (KCuFC) and potassium nickel ferrocyanide (KNiFC), preferably KCuFC.

[0010] The fiber material is cotton fiber, silk fiber, lotus stem, or other commercial fiber material that can form capillary channels and enable continuous liquid climbing.

[0011] The adsorbent is prepared by in-situ growth: first, the fiber is immersed in an aqueous solution of copper nitrate or nickel nitrate, allowing metal ions to be pre-adsorbed or fixed on the fiber surface and its near-surface region; then, the fiber is transferred to a potassium ferrocyanide solution to react and form the corresponding ferricyanide metal coordination adsorbent. The concentration of the copper nitrate or nickel nitrate aqueous solution is 0.1–0.4 mol / L, the concentration of the potassium ferrocyanide aqueous solution is 0.1–0.4 mol / L, the single immersion time is 1–5 h, and the immersion is repeated 1–3 times. Subsequently, the fiber is washed with deionized water and dried at 50–100 °C.

[0012] In a preferred embodiment, the fiber is first soaked in a 0.2 mol / L Cu(NO3)2·3H2O aqueous solution for 3 h, then transferred to a 0.2 mol / L K4Fe(CN)6 aqueous solution for 3 h, and the above alternating soaking operation is repeated. Subsequently, it is washed with deionized water and dried at 55 °C to obtain a fiber evaporative adsorber loaded with KCuFC.

[0013] The adsorbent loading region is located in the upper region along the capillary climbing direction, and the upper region is located in the section where competing ions have undergone significant crystallization and rubidium ions are relatively enriched.

[0014] Steps S2 to S4 are carried out in a sealed evaporation chamber, and the temperature, humidity, wind speed and air flow are adjusted by a blower to control the evaporation rate and enhance the spatial separation effect.

[0015] The desorbent used in the desorption step is an NH4Cl solution or a KCl solution with a concentration of 0.1–0.5 mol / L, in order to achieve effective elution and subsequent detection of rubidium in the target sample segment.

[0016] Compared with existing technologies, the innovation of this invention lies not only in fixing the adsorbent onto the fiber carrier, but also in proposing and realizing a separation mechanism that synergistically enhances "evaporation-crystallization-adsorption". First, the fiber material itself functions as both a liquid capillary transport channel and an evaporation interface carrier, enabling the feed liquid to continuously migrate and concentrate without complex pumping and additional separation units. Second, by loading the adsorbent onto the upper region where rubidium is more easily enriched, rather than uniformly loading it at arbitrary locations, the high-concentration regions of competing ions can be actively avoided at the structural level, significantly reducing the Na+ concentration. + K+ The selective adsorption sites are occupied; furthermore, the adsorbent is grown in situ and bonded to the fiber surface, which helps improve the uniformity and stability of the load and reduces the risk of loss during use of traditional powder adsorbents. This design couples physical spatial separation with chemical selective recognition, constituting a key technical feature that distinguishes this invention from existing single adsorption or single evaporation crystallization methods.

[0017] Compared with existing technologies, this invention has at least the following beneficial effects: First, by achieving stepwise crystallization and spatial separation of different ions through capillary transport and interfacial evaporation, the interference of high-concentration competing ions on rubidium adsorption can be weakened at the source. Second, by localizing selective adsorbents in the rubidium enrichment region, the adsorption process occurs in a more favorable local chemical environment, thereby significantly improving the separation performance of rubidium / sodium and rubidium / potassium. Third, the fiber carrier simultaneously serves as the adsorbent support, liquid transport, and solid-liquid separation carrier, avoiding the problem of subsequent separation difficulties of traditional powder adsorbents and simplifying the process flow. Fourth, the device described in this invention has a simple structure, readily available raw materials, and its performance can be optimized by adjusting the loading area, loading amount, and evaporation conditions, showing good potential for engineering scale-up and application. Fifth, the microscale synergistic separation approach established in this invention is not only applicable to rubidium ion extraction but can also provide technical reference for the highly selective separation of other trace alkali metals or target ions. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the process by which the adsorbent grows in situ on commercial fibers to form a fiber evaporative adsorber in this invention.

[0019] Figure 2 This is a schematic diagram of the experimental setup for the combined use of a sealed evaporator and a blower in implementing the method of this invention.

[0020] Figure 3 This invention illustrates the effect of fiber evaporative adsorbers on Rb under different competing ion conditions in embodiments of the present invention. + Na + and K + A diagram illustrating the recycling process.

[0021] Figure 4 This is a schematic diagram illustrating the principle of the method for extracting rubidium based on fiber evaporation adsorber and coordinated spatial separation according to the present invention.

[0022] Figure 5 for Figure 4 A magnified view of 'a' in the middle. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. To avoid excessive repetition, only five representative embodiments and one comparative example are listed below. Unless otherwise specified, the process conditions and analytical methods can be those conventional in the art.

[0024] Example 1: The preparation process of the KCuFC fiber evaporative adsorber is as follows: Figure 1 As shown. Commercial cotton fibers were selected as the substrate. A 20-30 cm section of the fiber, from the bottom upwards, was immersed in a 0.2 mol / L Cu(NO3)2·3H2O aqueous solution for 3 h, and then transferred to a 0.2 mol / L K4Fe(CN)6 aqueous solution for 3 h; this alternating immersion process was repeated. After the reaction, the fiber was washed with deionized water and dried at 55 °C to obtain a fiber evaporative adsorbent loaded with KCuFC. The adsorbent in the obtained sample was able to bind relatively uniformly to the fiber surface, providing a functional basis for subsequent evaporative separation and selective adsorption. + / Rb + The experimental setup for separating and extracting rubidium in the system is as follows: Figure 2 As shown. The obtained fiber evaporator adsorber was thoroughly wetted and air bubbles removed, then suspended on a support with its lower end in contact with the feed liquid and placed inside a sealed evaporation chamber. Evaporation adsorption experiments were conducted under heated air conditions. Under preferred conditions, the C in the feed liquid... Na+ =10 g / L, C Rb+ =10 mg / L, experimental environment: 55.5 ℃, relative humidity 12%, wind speed 0.85 m / s, air flow 420 m³ / s. 3 / h. After the reaction, the fiber evaporator was removed, the surface salt crust was removed, and a 2cm sample of the fiber loaded with adsorbent was taken for desorption and detection. When desorbing with 0.1 mol / L NH4Cl, the rubidium / sodium separation factor reached 234.0±41.6; when desorbing with 0.1 mol / L KCl, the rubidium / sodium separation factor was 470.0±27.6. When desorbing with 0.5 mol / L NH4Cl, the rubidium / sodium separation factor reached 343.9±28.6; when desorbing with 0.5 mol / L KCl, the rubidium / sodium separation factor was 595.0±0.9, and the KNiFC separation factor was 288.1±3.1. These are significantly higher than the separation level of the unloaded fiber, indicating that this invention can significantly improve the separation of Na+ through the synergistic effect of spatial separation and selective adsorption. + / Rb + Rubidium extraction efficiency in the system.

[0025] Example 2: The preparation steps of Example 1 were repeated, except that the concentrations of the precursor Cu(NO3)2·3H2O and K4Fe(CN)6 solutions were adjusted to 0.1 mol / L and 0.4 mol / L, respectively. All other process parameters remained identical to Example 1. When desorption was performed using 0.5 mol / L NH4Cl with a precursor solution concentration of 0.1 mol / L, the rubidium / sodium separation factor reached 72.8 ± 17.1. The performance was lower than in Example 1, possibly due to insufficient adsorbent loading, resulting in inadequate adsorption of rubidium ions. When desorption was performed using 0.5 mol / L NH4Cl with a precursor solution concentration of 0.4 mol / L, the rubidium / sodium separation factor reached 104.4 ± 14.5. The performance was lower than in Example 1, possibly due to excessive adsorbent loading, leading to excessive loss of rubidium ions before reaching their maximum adsorption position.

[0026] Example 3: Preparation of a KNiFC fiber evaporative adsorbent. The preparation steps of Example 1 were repeated, except that the precursor Cu(NO3)2·3H2O solution was replaced with Ni(NO3)2·3H2O; all other process parameters were identical to those in Example 1. When using 0.5 mol / L KCl for desorption, the rubidium / sodium separation factor reached 288.1 ± 3.1.

[0027] Example 4: K + / Rb + Rubidium separation in the system. Using the same experimental setup and operating procedures as in Example 1, the feed liquid was adjusted to C. K+ =10 g / L, C Rb+ =10 mg / L, analyzed under preferred desorption conditions. Results showed that the rubidium / potassium separation factor reached 24.7 ± 1.3. These results indicate that even at K... + This is related to Rb + In competing systems with similar properties, the present invention can still weaken the competition effect through spatial separation and achieve preferential capture of rubidium by means of the upper KCuFC adsorption region.

[0028] like Figure 3 As shown, the same apparatus and operating conditions as in Example 1 were used to test a 2 cm sample segment loaded with adsorbent fiber. When the Na content in the feed solution... + Concentration of 10 g / L, Rb + At a concentration of 10 mg / L, Rb + The recovery rate was 9.1% ± 1.4 percentage points, Na + The recovery rate is almost negligible; when the K content in the feed liquid is low... + Concentration of 10 g / L, Rb + At a concentration of 10 mg / L, Rb +The recovery rate was 3.7% ± 0.1 percentage points, K + The recovery rate is almost negligible. These results demonstrate that the fiber separator has selective separation capability for rubidium ions and shows promising application prospects in the field of rubidium resource separation and recovery. Figure 4 This is a schematic diagram illustrating the separation principle of the present invention. The present invention utilizes the differences in solubility and concentration between different ions to achieve stepwise crystallization, thereby reducing the competing ion Na+ in the system. + K + Interference with the separation process; simultaneously, by loading KCuFC adsorbent into specific regions of the fiber, its ability to resist Rb is enhanced. + It has a specific adsorption effect, thereby realizing Rb + Selective separation and enrichment effectively improve separation efficiency. Figure 5 for Figure 4 An enlarged view of a single-fiber evaporative adsorber provides a more intuitive demonstration of its separation principle.

[0029] Comparative Example 1: Pure cotton fibers without adsorbent were subjected to Na treatment under the same heated air conditions as in Example 2. + / Rb + System experiments were conducted. The results showed that the rubidium / sodium separation factor was only 12.6±1.2, which was significantly lower than that of the fiber evaporation adsorber system of the present invention. This indicates that although relying solely on fiber evaporation crystallization can achieve a certain degree of spatial separation, it is difficult to obtain high selectivity. Only by effectively combining the upper localized adsorption with the front-end stepwise crystallization can a significantly improved rubidium extraction performance be achieved.

Claims

1. A method for extracting rubidium based on a fiber evaporative adsorber in synergistic spatial separation, characterized in that, Using fibers with capillary transport capabilities as a substrate, a ferricyanide metal coordination adsorbent is grown in situ in the upper region along the liquid migration direction to form a fiber evaporative adsorbent. In use, the lower end of the fiber evaporative adsorbent is brought into contact with a rubidium-containing feed solution, which is a binary solution containing sodium and rubidium or potassium and rubidium. Driven by capillary force, the binary solution containing sodium and rubidium or potassium and rubidium rises continuously along the fiber and undergoes interfacial evaporation under the influence of air flow and temperature field. The adsorbent in the upper region selectively captures rubidium ions, achieving efficient separation and enrichment of rubidium.

2. The method for extracting rubidium based on a fiber evaporator-adsorbent synergistic spatial separation according to claim 1, characterized in that, The upper region is 20 to 30 centimeters above the bottom of the fiber.

3. A method for extracting rubidium based on a fiber evaporator-adsorbent synergistic spatial separation according to claim 1 or 2, characterized in that, The specific steps are as follows: S1. Using a fiber material with capillary transport capacity as a substrate, an iron cyanide metal coordination adsorbent is grown in situ in the upper region of the fiber material to obtain a fiber evaporative adsorbent. S2. The lower part of the fiber evaporator is brought into contact with the rubidium-containing raw material liquid, and the raw material liquid is moved upward along the fiber under capillary action and continuously concentrated under evaporation. S3. By utilizing the differences in solubility and initial concentration of raw material solution between rubidium salt and competing ion salt, the competing ions preferentially crystallize at the lower position of the fiber, while rubidium crystallizes after being relatively enriched at the higher position of the fiber, thereby achieving spatial separation of rubidium and competing ions. S4. The rubidium ions in the enrichment region are selectively adsorbed by the adsorbent loaded on the upper region of the fiber. S5. Desorb the adsorbed fiber evaporator to obtain a rubidium-containing desorbent.

4. The method for extracting rubidium based on a fiber evaporator-adsorbent synergistic spatial separation according to claim 3, characterized in that, The ferricyanide metal coordination adsorbent is at least one of potassium copper ferrocyanide (KCuFC) and potassium nickel ferrocyanide (KNiFC).

5. The method for extracting rubidium based on a fiber evaporator-adsorbent synergistic spatial separation according to claim 3, characterized in that, The fiber material is cotton fiber, silk fiber, or lotus stem.

6. The method for extracting rubidium based on a fiber evaporator-adsorbent synergistic spatial separation according to claim 3, characterized in that, The adsorbent is prepared by in-situ growth method: first, the fiber is immersed in an aqueous solution of copper nitrate or nickel nitrate to pre-adsorb or fix metal ions on the fiber surface and its near-surface area, and then the fiber is transferred to potassium ferrocyanide solution to react and form the corresponding ferricyanide metal coordination adsorbent.

7. The method for extracting rubidium based on a fiber evaporator-adsorbent synergistic spatial separation according to claim 6, characterized in that, The concentration of the copper nitrate or nickel nitrate aqueous solution is 0.1–0.4 mol / L, the concentration of the potassium ferrocyanide aqueous solution is 0.1–0.4 mol / L, the single soaking time is 1–5 h, and the soaking is repeated 1–3 times. Then, the solution is washed with deionized water and dried at 50–100 °C.

8. The method for extracting rubidium based on a fiber evaporator-adsorbent synergistic spatial separation according to claim 7, characterized in that, First, the fiber was soaked in a 0.2 mol / L Cu(NO3)2·3H2O aqueous solution for 3 h, and then transferred to a 0.2 mol / L K4Fe(CN)6 aqueous solution for 3 h. The above alternating soaking operation was repeated. After washing with deionized water and drying at 55 °C, a fiber evaporative adsorber loaded with KCuFC was obtained.

9. The method for extracting rubidium based on a fiber evaporator-adsorbent synergistic spatial separation according to claim 3, characterized in that, Steps S2 to S4 are carried out in a sealed evaporation chamber, and the temperature, humidity, wind speed and air flow are adjusted by a blower.

10. The method for extracting rubidium based on a fiber evaporator-adsorbent synergistic spatial separation according to claim 3, characterized in that, The desorbent used in the desorption step is an NH4Cl solution or a KCl solution with a concentration of 0.1–0.5 mol / L, in order to achieve effective elution and subsequent detection of rubidium in the target sample segment.

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