A controlled removal and rapid identification method for chromium(VI) ions in vanadium(V) aqueous solution

Abstract

This invention belongs to the field of fine chemical synthesis and solution separation and purification, and relates to a method for the controllable removal and rapid identification of chromium(VI) ions in vanadium(V) aqueous solutions. Utilizing a macroporous organic adsorbent, chromium(VI) ions are continuously adsorbed through multiple contact-separation processes under non-equilibrium conditions at low pH to achieve controllable removal of chromium ions, thereby increasing the vanadium-chromium ratio in the solution and improving the purity of the vanadium product. Then, biodegradable riboflavin is used as a probe, and ultraviolet spectroscopy is employed to rapidly identify the remaining chromium(VI) ions in the vanadium(V) aqueous solution. This method achieves high chromium removal efficiency; by controlling appropriate chromium removal conditions, controllable purification can be achieved, providing technical support for online monitoring and intelligent production.

Description

Technical Field

[0001] This invention belongs to the field of fine chemical synthesis and solution separation and purification, and relates to a method for the controllable removal and rapid identification of chromium(VI) ions in vanadium(V) aqueous solution. Background Technology

[0002] Vanadium plays a vital role in both industrial applications and strategic resources, particularly in aerospace, steel smelting, petrochemicals, military manufacturing, industrial catalysis, and flow batteries. The main raw materials for vanadium extraction are vanadium slag, vanadium-titanium magnetite, and vanadium-bearing phosphate rock. [Ren Xueyou. Current Status and Market Prospects of Metallic Vanadium [J]. World Nonferrous Metals, 2004, (2): 34.] Currently, industrialized extraction processes mainly include roasting-water leaching, calcification-roasting-alkali leaching, vanadium extraction from molten vanadium slag oxidation, and direct sulfuric acid leaching. However, regardless of the extraction process, the purity of the target material must be considered. Chromium, with similar properties to vanadium, readily coexists in aqueous solutions, requiring the removal of impurities to obtain a high-purity vanadium product. Therefore, purification involves identification and impurity removal processes.

[0003] Vanadium-titanium magnetite, a polymetallic associated ore, contains abundant iron, vanadium, titanium, chromium, and other elements, and is an important raw material source for my country's vanadium industry. Currently, the blast furnace-converter method is commonly used to enrich vanadium-containing steel slag from vanadium-titanium magnetite: vanadium is reduced into the molten steel in the blast furnace and then enriched into the slag through selective oxidation, resulting in vanadium-containing steel slag with a V₂O₅ content greater than 10%. Vanadium-containing steel slag is a very important and valuable vanadium resource, from which V₂O₅ extraction accounts for more than 88% of the total production. [Li Xuan, Wei Yanfang, Wu Yixi, et al. Research progress on vanadium-chromium separation in the preparation process of high-purity vanadium pentoxide [J / OL]. Jiangxi Metallurgy, 1-14 [2024-04-24]. http: / / kns.cnki.net / kcms / detail / 36.1105.TF.20240305.1226.006.html.] Among these, sodium roasting is the mainstream process in industrial production. Currently, the main impurity removal processes for alkaline vanadium solutions obtained from sodium roasting-water leaching include chemical precipitation, solvent extraction, ion exchange, adsorption, and crystallization. Firstly, chemical precipitation introduces new impurities while removing chromium ions, resulting in lower product purity. Furthermore, when the vanadium and chromium concentrations in the solution are similar, co-precipitation and crystallization may occur, leading to poor vanadium-chromium separation. Crystallization is primarily suitable for the effective separation of high-concentration vanadium-chromium solutions under alkaline conditions. During crystallization, the crystallization concentration must be strictly controlled to prevent the simultaneous precipitation of impurities, which would affect product purity. Moreover, controlling the crystallization process parameters is complex and time-consuming. Solvent extraction typically involves organic phase extraction, which is complex, time-consuming, and has high environmental and energy consumption requirements, resulting in higher production costs. Resin adsorption can achieve highly selective adsorption and desorption of chromium(VI) ions in vanadium(V) solutions by taking advantage of the difference in the binding ability of vanadium and chromium to the resin, thereby achieving the separation of vanadium and chromium. However, current research reports focus on the preferential adsorption of vanadium to remove vanadium ions from chromium-containing solutions and produce qualified chromium products. How to quickly identify chromium ions from vanadium solutions and controllably remove chromium remains a challenge.

[0004] Therefore, in summary, a suitable method has been developed that can effectively remove chromium(VI) ions from vanadium solutions, rapidly identify the remaining chromium ion content in the vanadium solution after chromium(VI) ion removal, and achieve controllable production of high-purity vanadium solutions, laying a technical foundation for the implementation of intelligent manufacturing. Summary of the Invention

[0005] To overcome the above problems, this invention provides a rapid identification and removal method for chromium (VI) ions in vanadium (V) aqueous solutions. This method can rapidly identify chromium (VI) ions in solution and perform controlled chromium removal without introducing indicators that cause secondary pollution. Specifically, a macroporous organic adsorbent is used to achieve controlled removal of chromium (VI) ions through multiple contact-separation adsorption processes under non-equilibrium conditions at low pH, increasing the vanadium-chromium ratio in the solution and thus improving the purity of the vanadium product. Then, biodegradable riboflavin is used as a probe, and ultraviolet spectroscopy is employed to rapidly identify the remaining chromium (VI) ions in the vanadium (V) aqueous solution. This method achieves high chromium removal efficiency. By controlling appropriate chromium removal conditions, controlled purification can be achieved, providing technical support for online monitoring and intelligent production.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for the controllable removal and rapid identification of chromium(VI) ions in vanadium(V) aqueous solution is proposed. First, chromium(VI) ions are removed by continuously adsorbing macroporous organic adsorbents under non-equilibrium conditions. Then, riboflavin is used as a probe and ultraviolet spectroscopy is used as a tool to rapidly identify the remaining chromium(VI) ions in the adsorbed vanadium(V) aqueous solution.

[0008] The macroporous organic adsorbent mentioned above refers to an adsorbent containing sulfonic acid groups, preferably D001 resin.

[0009] The amount of macroporous organic adsorbent used is: the mass-to-volume ratio of macroporous organic adsorbent to vanadium(V) aqueous solution is 1:(5-10)g / L.

[0010] The macroporous organic adsorbent is replaced every 15-20 minutes.

[0011] Before adsorption, the pH of the vanadium(V) aqueous solution was adjusted to 4-5 with hydrochloric acid, and the concentration of chromium(VI) ions in the vanadium(V) aqueous solution was determined by plasma atomic emission spectrometry.

[0012] The concentration of riboflavin in the vanadium(V) aqueous solution after adsorption is 12-17 ppm; the pH of the vanadium(V) aqueous solution after the addition of riboflavin is 5-8.

[0013] When performing ultraviolet (UV) spectroscopy tests using a UV spectrometer, based on the previously determined concentration of chromium (VI) ions in the vanadium (V) aqueous solution, calculate the amount of deionized water required to dilute the original vanadium (V) aqueous solution to 20-50 ppm. Then, add the corresponding amount of deionized water to the adsorbed vanadium (V) aqueous solution for dilution. Next, set the absorption wavelength of the UV spectrometer to 370-375 nm, read the absorbance value, and calculate the concentration of the remaining chromium (VI) ions in the vanadium (V) aqueous solution using the absorbance value.

[0014] The beneficial effects of this invention are:

[0015] This invention achieves successful removal of chromium(VI) ions from vanadium(V) solutions through continuous adsorption under non-equilibrium conditions, and enables rapid identification of chromium(VI) ions in vanadium(V) solutions using ultraviolet (UV) spectroscopy. Compared to traditional inductively coupled plasma atomic emission spectrometry (ICP), which has a high detection limit and requires samples to be sent to specialized analytical institutions, this method utilizes a UV spectrometer that can be readily available in most laboratories. It allows for immediate determination of chromium(VI) ion content after adsorption, with an extremely low detection limit. This method offers excellent separation performance, is simple to operate, and is environmentally friendly. Attached Figure Description

[0016] Figure 1 This is a process flow diagram of the method of the present invention.

[0017] Figure 2 This is the infrared spectrum of a macroporous adsorbent.

[0018] Figure 3 This is the UV spectrum of riboflavin detection of V(V) doped with different proportions of Cr(VI).

[0019] Figure 4 , 5 Figure 6 shows the relationship between the number of cycles and the ion concentration of the mixture. Detailed Implementation

[0020] The process flow of this invention is as follows: Figure 1 As shown, the present invention will be further described in detail below with reference to specific embodiments, but the present invention is not limited to the specific embodiments.

[0021] Example 1

[0022] First, a series of vanadium-chromium mixed solutions were prepared, with the V(V) concentration fixed at 10 ppm and the V(V) to Cr(VI) molar ratio ranging from 10:1 to 10:20. Using a 15% riboflavin solution as a probe, the solutions were scanned using ultraviolet spectroscopy. The results are as follows: Figure 3As shown, the absorbance peaks in the ultraviolet region appear at 265.5 nm, 372 nm, and 445 nm, showing a clear linear relationship with the increase of Cr(VI) addition. The peak at 445 nm is not obvious when the chromium concentration is low. The most obvious peak is at 373 nm, where the absorbance increases significantly with the increase of Cr(VI) concentration, and there is a significant increase even at low concentrations. That is, it shows a linear relationship with the V(V) / Cr(VI) ratio. Therefore, this characteristic peak can be identified as the characteristic peak of the ultraviolet spectrum for riboflavin detection of chromium in vanadium(V).

[0023] Example 2

[0024] The vanadium (V) and chromium (VI) ion solution was first calibrated using an inductively coupled plasma optical emission spectrometer (ICP). (V) =2.04 g / L, C (Cr) =1.98 g / L). The pH was controlled at 5 ± 0.05 using hydrochloric acid. 300 mL of the solution was placed into a 500 mL Erlenmeyer flask, and then 0.3 g of the pretreated sulfonic acid-containing adsorbent A was added at a solid-liquid ratio (g / L) of 1:10. The Erlenmeyer flask was stirred at 300 rpm for 20 min, and then the solid-liquid mixture was separated by vacuum filtration to remove adsorbent A (D001 resin). The mixture was returned to the Erlenmeyer flask container, and this was recorded as one cycle sample. Another 100 μL of vanadium solution was taken and diluted to 100 mL. Using 15 ppm riboflavin as a probe, the absorbance was recorded at a wavelength of 372 nm. Figure 3 The chromium ion concentration was recorded by comparing the standard spectrum with the vanadium solution. After collecting the vanadium solution, 0.3 g of adsorbent A was added again, and the above operation was repeated. The resulting solutions were recorded as the 2nd, 3rd, 4th, 5th, and 6th cycle samples, respectively. The chromium data from each 372 nm test and the vanadium ion concentration determined by ICP were plotted as follows. Figure 4 As shown in the figure, the vanadium-chromium ratio increases accordingly using this method. After six cycles, the vanadium-chromium ratio increases from 1.03 to 36.3, achieving a chromium removal rate of 97.53% and a vanadium loss rate of less than 13%. Furthermore, the number of adsorption cycles can be controlled during this process. The infrared spectrum of adsorbent A containing sulfonic acid groups is shown in the figure. Figure 2 As shown.

[0025] Example 3

[0026] Take a mixed solution of vanadium(V) and chromium(VI) ions (C (V) =64.61g / L,C (VI)=8.84 g / L) The pH of the solution was adjusted to approximately 4.5 ± 0.1 using hydrochloric acid. 100 mL of the solution was transferred to a 250 mL Erlenmeyer flask. Adsorbent A, which had undergone pretreatment, was added at a solid-liquid ratio of 1:8 (g / L), i.e., 0.08 g of sulfonic acid-containing adsorbent A was added to the Erlenmeyer flask containing the vanadium-chromium mixture. The Erlenmeyer flask was placed on a shaker and shaken for 15 min at a frequency of 200 rpm. The solid-liquid mixture was then separated by vacuum filtration to remove adsorbent A. The mixture was returned to the Erlenmeyer flask container, and this was recorded as one cycle sample. Another 100 μL of vanadium solution was taken and diluted to 100 mL. Using 12 ppm riboflavin as a probe, the absorbance was recorded at a wavelength of 372 nm. Figure 3 The chromium ion concentration was recorded by comparing the standard spectrum with the vanadium solution. After collecting the vanadium solution, 0.3 g of adsorbent A was added again, and the above operation was repeated. The resulting solutions were recorded as the 2nd, 3rd, 4th, 5th, 6th, and 7th cycle samples, respectively. The chromium data from each 372 nm test and the vanadium ion concentration determined by ICP were plotted as follows. Figure 5 As shown in the figure, the vanadium-chromium ratio increases accordingly using this method. After 7 cycles, the vanadium(V) ion concentration in the solution decreased from 64.61 g / L to 57.93 g / L, with a loss rate of 10.34%. Meanwhile, the chromium(VI) ion concentration decreased from 8.84 g / L to 0.44 g / L, with a removal rate of 95.02%, and the vanadium-chromium ratio increased from 7.31 to over 133.60.

[0027] It is evident that this method is also applicable in mixed solutions with higher vanadium concentrations (greater than 60 g / L).

[0028] Example 4

[0029] Take a mixed solution of vanadium(V) and chromium(VI) ions (C (V) =19.49 g / L, C (VI) =2.42 g / L). The pH was controlled at 4.0 ± 0.05 with hydrochloric acid. 100 mL was transferred to a 250 mL Erlenmeyer flask. The pretreated sulfonic acid-containing adsorbent was added at a solid-liquid ratio of 1:5 (g / L), i.e., 0.05 g of adsorbent A was added to the Erlenmeyer flask containing the vanadium-chromium mixture. The Erlenmeyer flask was placed on a shaker and shaken for 18 min at a frequency of 200 rpm. The mixture was returned to the Erlenmeyer flask container, which was recorded as one cycle sample. Another 100 μL of vanadium solution was taken and diluted to 100 mL. The absorbance was recorded at a wavelength of 372 nm using 17 ppm riboflavin as a probe. Figure 3 The chromium ion concentration was recorded by comparing the standard spectrum with the vanadium solution. After collecting the vanadium solution, 0.3 g of adsorbent A was added again, and the above operation was repeated. The resulting solutions were recorded as the 2nd, 3rd, 4th, and 5th cycle samples, respectively. The chromium data from each 372 nm test and the vanadium ion concentration determined by ICP were plotted as follows: Figure 6As shown in the figure, by using this method to increase the vanadium-chromium ratio, after 5 cycles, the vanadium(V) ion concentration in the solution decreased from 19.49 g / L to 17.21 g / L, with a loss rate of 11.7%. Meanwhile, the chromium(VI) ion concentration decreased from 2.42 g / L to 0.11 g / L, with a removal rate of 95.87%. The vanadium-chromium ratio increased from 8.05 to 156.45.

Claims

1. A method for controllable removal and rapid identification of chromium (VI) ions in vanadium (V) aqueous solution, characterized in that, First, the macroporous structure organic adsorbent is used to remove chromium ions under non-equilibrium conditions by continuously adsorbing chromium (VI) ions; then, riboflavin is used as a probe, and an ultraviolet spectrometer is used as a tool to quickly identify the residual chromium (VI) ions in the adsorbed vanadium (V) aqueous solution; the macroporous structure organic adsorbent is replaced every 15-20 min; the concentration of riboflavin in the adsorbed vanadium (V) aqueous solution is 12-17 ppm; and the pH of the vanadium (V) aqueous solution after adding riboflavin is 5-8.

2. The method for controllable removal and rapid identification of chromium (VI) ions in vanadium (V) aqueous solution according to claim 1, characterized in that, Before adsorption, the pH of the vanadium (V) aqueous solution is adjusted to 4-5 by hydrochloric acid, and the concentration of chromium (VI) ions in the vanadium (V) aqueous solution is determined by using an inductively coupled plasma emission spectrometer; when the ultraviolet spectrometer is used for ultraviolet spectrum testing, according to the concentration of chromium (VI) ions in the vanadium (V) aqueous solution determined before adsorption, the amount of deionized water required to dilute the original concentration of chromium (VI) ions in the vanadium (V) aqueous solution to 20-50 ppm is calculated, and then the corresponding amount of deionized water is added to the adsorbed vanadium (V) aqueous solution for dilution; then the absorption wavelength of the ultraviolet spectrometer is set to 370-375 nm, and the absorbance value is read, and the concentration of residual chromium (VI) ions in the vanadium (V) aqueous solution is calculated by the absorbance value.

3. The method for controllable removal and rapid identification of chromium (VI) ions in vanadium (V) aqueous solution according to claim 1 or 2, characterized in that, The macroporous structure organic adsorbent refers to an adsorbent containing a pair of sulfonic acid groups.

4. The method for controllable removal and rapid identification of chromium (VI) ions in vanadium (V) aqueous solution according to claim 3, characterized in that, The macroporous structure organic adsorbent is D001 resin.

5. The method for controllable removal and rapid identification of chromium (VI) ions in vanadium (V) aqueous solution according to claim 1 or 2 or 4, characterized in that, The use amount of the macroporous structure organic adsorbent is that the mass-volume ratio between the macroporous structure organic adsorbent and the vanadium (V) aqueous solution is 1: (5-10) g / L.

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