Colorable iron ion complexing agent, desulfurizing agent, preparation method thereof, and desulfurization application

Abstract

The present invention discloses a colorable iron ion complexing agent, a desulfurizing agent, a preparation method thereof, and desulfurization applications. The colorable iron ion complexing agent has the following general chemical structural formula: wherein: R1 is Na or K; R2 is one of the following substituted atoms or substituents: H-CH3-, HOCH2NH2COCH2CH2-CH3CHOH-. The desulfurizing agent of the present invention comprises deionized water, a soluble iron salt, the colorable iron ion complexing agent, triethylamine, an inorganic base, and a defoaming agent. The present invention can effectively form a stable water-soluble complex with iron ions to achieve efficient desulfurization; the color change of the complex facilitates monitoring and replenishment of iron ion loss during the desulfurization process, simplifies the operation process, and does not require complex equipment; and uses inexpensive and readily available raw materials, facilitating large-scale production.

Description

Technical Field

[0001] The present invention relates to the fields of environmental protection and gas purification, and in particular to a complexing agent for iron ions capable of developing color, a desulfurizing agent, a preparation method thereof, and desulfurization application thereof. Background Art

[0002] Hydrogen sulfide is a colorless, toxic gas that can damage the human respiratory tract, eyes, and skin. Long-term exposure can cause chronic toxic reactions, which can be fatal in severe cases. Hydrogen sulfide has a wide range of sources, including oilfield refining exhaust, coke oven gas, and natural gas, as well as industrial gases such as natural gas. It also originates from the anaerobic decomposition of organic waste in processes such as papermaking, pharmaceuticals, leather processing, wastewater treatment, and garbage disposal. In recent years, with the rapid development of human society, the environmental problems caused by hydrogen sulfide emissions have become increasingly severe, creating an urgent need to address this issue.

[0003] Complex iron desulfurization technology is to use complexed Fe in aqueous solution 3+ The hydrogen sulfide gas is oxidized to generate elemental sulfur solid, thereby achieving the removal of hydrogen sulfide gas. The complexed Fe 2+ Oxidized by the incoming air, it is regenerated into a complex state of Fe 3+ , thus implementing the cycle of the entire desulfurization process. In the entire process of hydrogen sulfide removal, the complexed Fe 3 + As a catalyst, it plays a key role. However, due to the degradation of the complexing agent, the recovery of solid sulfur, the generation of insoluble iron salts, etc., as the desulfurization process proceeds, the complexed Fe 3+ There is an unavoidable loss, which reduces the desulfurization effect. Therefore, in the actual hydrogen sulfide removal process, it is necessary to regularly measure the loss of complex iron and replenish the complex iron in time.

[0004] Currently, EDTA-complexed iron is commonly used in industry. Representative methods for measuring complexed iron content include flame atomic absorption spectroscopy and spectrophotometry. However, these methods require specialized testing equipment, sample preparation, and instrument testing procedures, resulting in cumbersome processes and significant inconvenience in practical applications. Therefore, a new method or material is urgently needed that is simple and convenient to use and can monitor complexed iron content in desulfurizers without the need for sophisticated instrumentation. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a chelating agent, a desulfurizing agent, a preparation method thereof, and a desulfurization application thereof that are low-cost, simple to operate, do not require any instruments or equipment, and can conveniently monitor the iron content, so as to achieve timely replenishment of the chelated iron in the chelated iron desulfurization process and achieve a long-lasting and stable desulfurization effect.

[0006] The complexing agent molecule provided by the present invention is a multidentate ligand containing multiple groups with coordination properties such as phenolic hydroxyl, secondary amine, carboxyl, and imidazole. It can coordinate with iron ions to form a stable water-soluble complex, achieving a high hydrogen sulfide removal rate. At the same time, the phenol structure in the complexing agent molecule has a color-developing property for iron ions. Its sensitive color change phenomenon with concentration can be used to conveniently monitor the complexed iron content, facilitate timely replenishment of lost complexed iron, and maintain a long-lasting and stable desulfurization effect.

[0007] The present invention provides a complexing agent for iron ions that can develop color, and its general chemical structure is as follows:

[0008]

[0009] The symbols in the general formula have the following meanings:

[0010] R1 is Na or K;

[0011] R2 is one of the following substituted atoms or substituents:

[0012] H-, CH3-, HOCH2-, NH2COCH2CH2-, CH3CHOH-,

[0013]

[0014] The present invention also provides a method for synthesizing the above-mentioned colorable iron ion complexing agent, the specific steps of which are as follows:

[0015] (1) dissolving an amino acid and a base in an equimolar ratio in a polar solvent to form an amino acid salt solution;

[0016] (2) dissolving salicylaldehyde in a polar solvent to obtain a salicylaldehyde solution;

[0017] (3) dripping the salicylaldehyde solution into the amino acid salt solution;

[0018] (4) adding sodium borohydride;

[0019] (5) Evaporate the solvent and recrystallize.

[0020] Preferably, the molar ratio of salicylaldehyde to amino acid is 0.9-1.2.

[0021] Preferably, the molar ratio of sodium borohydride to salicylaldehyde is 1-3.

[0022] Preferably, the mass ratio of amino acid to polar solvent in step (1) is 0.001-2.

[0023] Preferably, in step (2), the mass ratio of salicylaldehyde to polar solvent is 0.001-2.

[0024] Preferably, the amino acid is one of glycine, alanine, serine, glutamine, threonine, tyrosine and histidine.

[0025] Preferably, the base is sodium hydroxide or potassium hydroxide.

[0026] Preferably, the polar solvent is one of ethanol, methanol and water or a mixture thereof.

[0027] The present invention also provides a desulfurizing agent, which comprises deionized water, a soluble iron salt, a complexing agent of the colorable iron ion, triethylamine, an inorganic base, and a defoaming agent.

[0028] Preferably, the soluble iron salt is ferric chloride, ferric sulfate or ferric nitrate, which accounts for 0.01wt%-2.5wt% of the mass fraction of the desulfurizer;

[0029] Preferably, the molar ratio of the colorable iron ion complexing agent to the soluble iron salt is (1-50):1;

[0030] Preferably, the molar ratio of the triethylamine to the colorable iron ion complexing agent is (1-10):1;

[0031] Preferably, the inorganic base is sodium carbonate and / or potassium carbonate, which is used to adjust the pH value of the desulfurizer solution to 7-10;

[0032] Preferably, the defoaming agent is polyethylene glycol with an average molecular weight ranging from 400 to 4000, and accounts for 1 wt% to 3 wt% of the mass fraction of the desulfurizer.

[0033] The present invention also provides a method for preparing the above-mentioned desulfurizing agent, comprising the following steps:

[0034] (1) dissolving the colorable iron ion complexing agent in deionized water, adding a soluble iron salt, stirring to dissolve, dropping triethylamine, and stirring for 5-30 minutes to form a complex iron aqueous solution;

[0035] (2) Add a defoaming agent to the above complex iron aqueous solution and adjust the pH value of the solution to 7-10 with an inorganic base.

[0036] The present invention also provides an application of a desulfurizing agent in a simple calculation method for complex iron content.

[0037] The colorable iron ion complexing agent and desulfurizing agent provided by the present invention have multiple beneficial effects. They can effectively form a stable water-soluble complex with iron ions, achieving efficient desulfurization. The color change of the complex facilitates monitoring and replenishing iron ion loss during the desulfurization process, simplifying the operation process and eliminating the need for complex equipment. Moreover, they use inexpensive and readily available raw materials, facilitating large-scale production. These characteristics give them significant advantages in gas purification, especially desulfurization applications, and provide an effective way to achieve long-lasting and stable desulfurization effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0039] Figure 1 This is a physical picture of the diluted solution of the desulfurizer in Example 2. DETAILED DESCRIPTION

[0040] The present invention can be more easily understood by referring to the following detailed description of the preferred embodiments of the present invention and the included examples. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those generally understood by those of ordinary skill in the art to which the present invention belongs. When there is a conflict, the definitions in this specification sheet shall prevail. The following examples illustrate the present invention in more detail, but are not intended to limit the present invention to these examples.

[0041] A complexing agent for iron ions that can develop color, the general chemical structure of which is as follows:

[0042]

[0043] The symbols in the general formula have the following meanings:

[0044] R1 is Na or K;

[0045] R2 is one of the following substituted atoms or substituents:

[0046] H-, CH3-, HOCH2-, NH2COCH2CH2-, CH3CHOH-,

[0047]

[0048] The colorable iron ion complexing agent of the present invention utilizes the coordination groups such as phenolic hydroxyl group, secondary amine, carboxyl group, imidazole in its structure to form multi-point coordination with iron ion, and then constructs a stable water-soluble complex. The presence of these coordination groups significantly enhances the stability and water solubility of the complex, ensuring that hydrogen sulfide is efficiently captured and removed during the desulfurization process. Through the synergistic effect of these functional groups, the complex can sensitively respond to the change of iron ion concentration and is intuitively displayed by color change, thereby providing a kind of convenient and effective means for monitoring and controlling during the desulfurization process.

[0049] A method for synthesizing a colorable iron ion complexing agent, comprising the following steps:

[0050] (1) dissolving an amino acid and a base in an equimolar ratio in a polar solvent to form an amino acid salt solution;

[0051] (2) dissolving salicylaldehyde in a polar solvent to obtain a salicylaldehyde solution;

[0052] (3) adding the salicylaldehyde solution dropwise to the amino acid salt solution and stirring for 0.5-6 hours;

[0053] (4) Add sodium borohydride and stir for 0.5-6h;

[0054] (5) evaporating the solvent and recrystallizing;

[0055] The molar ratio of salicylaldehyde to amino acid is 0.9-1.2;

[0056] The molar ratio of sodium borohydride to salicylaldehyde is 1-3;

[0057] In step (1), the mass ratio of amino acid to polar solvent is 0.001-2;

[0058] In the step (2), the mass ratio of salicylaldehyde to the polar solvent is 0.001-2;

[0059] The amino acid is one of glycine, alanine, serine, glutamine, threonine, tyrosine and histidine;

[0060] The alkali is sodium hydroxide or potassium hydroxide;

[0061] The polar solvent is one of ethanol, methanol and water or a mixture thereof.

[0062] The specific reaction route is shown below.

[0063]

[0064] Among them, R2 is a structural formula, and the amino acids corresponding to the structure listed therein and its synthetic source and the selected amino acids in order are glycine, alanine, serine, glutamine, threonine, tyrosine and histidine.

[0065] The beneficial effects of the complexing agent prepared by the present invention are:

[0066] 1. The complexing agent can form multiple coordination effects with iron ions. The formed complex iron has a stable structure, good water solubility, and a high hydrogen sulfide removal rate. It is suitable as a catalyst for wet oxidation desulfurization of hydrogen sulfide.

[0067] 2. The complex formed by the complexing agent molecules and iron ions is reddish-brown, which is sensitive to the human eye. The concentration of the complexed iron can be calculated by utilizing the concentration-sensitive color change of the solution. The operation is simple and does not require any equipment. It is suitable for monitoring and replenishing lost complexed iron during the actual desulfurization process, ensuring a stable and long-lasting desulfurization effect.

[0068] 3. Raw materials such as salicylaldehyde and amino acids used in the synthesis of complexing agents are widely available, cheap and easy to obtain, and can be produced on a large scale.

[0069] A desulfurizing agent, the raw materials of which include deionized water, soluble iron salt, the complexing agent of the above-mentioned colorable iron ion, triethylamine, inorganic base, and defoaming agent;

[0070] The soluble iron salt is ferric chloride, ferric sulfate or ferric nitrate, which accounts for 0.01wt%-2.5wt% of the mass fraction of the desulfurizer;

[0071] The molar ratio of the colorable iron ion complexing agent to the soluble iron salt is (1-50):1;

[0072] The molar ratio of triethylamine to the complexing agent for colorable iron ions is (1-10):1;

[0073] The inorganic base is sodium carbonate and / or potassium carbonate, which is used to adjust the pH value of the desulfurizer solution to 7-10;

[0074] The defoaming agent is polyethylene glycol, the average molecular weight of which is in the range of 400-4000, and accounts for 1wt%-3wt% of the mass fraction of the desulfurizer.

[0075] The preparation method of the desulfurizer comprises the following steps:

[0076] (1) dissolving the colorable iron ion complexing agent in deionized water, adding a soluble iron salt, stirring to dissolve, dropping triethylamine, and stirring for 5-30 minutes to form a complex iron aqueous solution;

[0077] (2) Add a defoaming agent to the above complex iron aqueous solution and adjust the pH value of the solution to 7-10 with an inorganic base.

[0078] In the present invention, the complexing agent of the iron ion that can develop color is the main body of the synthesis reaction, and its role is to react with the iron ion to form a stable complex. It can form a specific complex with the iron ion and show color to indicate the presence of the iron ion.

[0079] Ferric chloride is a commonly used iron source that can provide Fe 3+ ions. Ferric chloride reacts with the complexing agent to form a complex, which is the reason why the desulfurizer solution appears colored. In addition, the Fe 3+ It has strong oxidizing properties and can reduce hydrogen sulfide to generate solid sulfur through oxidation reaction, thus achieving the purpose of removing toxic gas hydrogen sulfide.

[0080] Triethylamine is an organic base used to neutralize the acid produced during the reaction between the complexing agent and ferric chloride, and promote the formation of the complex.

[0081] Sodium carbonate and potassium carbonate are commonly used alkaline chemical reagents. In the present invention, sodium carbonate and potassium carbonate are added to adjust the pH value of the solution to an alkaline environment. Since hydrogen sulfide is weakly acidic, alkaline aqueous solution can increase the solubility of hydrogen sulfide, making it easier for it to react with Fe in the complex in the solution. 3+ Oxidation reaction improves the removal efficiency of toxic gas hydrogen sulfide.

[0082] Polyethylene glycol is used as a defoaming agent. During the desulfurization process, the introduction of hydrogen sulfide waste gas and air into the desulfurizer aqueous solution generates a large number of bubbles. These bubbles affect the sedimentation and aggregation of the generated solid sulfur, hindering its recovery. Polyethylene glycol is used to reduce foaming during the reaction and promote the sedimentation, aggregation, and recovery of the solid sulfur.

[0083] The desulfurizing agent of the present invention achieves an efficient hydrogen sulfide removal effect through carefully designed components and reaction steps. By forming a stable complex with a colorable iron ion complexing agent and an iron salt, not only the desulfurization efficiency is improved, but also the iron ion concentration is easily monitored by color change, simplifying the operation process. The addition of triethylamine optimizes the reaction environment and promotes the formation of the complex. The use of an inorganic base adjusts the solution pH value to an ideal range, enhances the solubility of hydrogen sulfide, and thus improves the desulfurization efficiency. The application of a defoaming agent reduces the generation of bubbles during operation, which is conducive to the sedimentation and recovery of solid sulfur. Overall, the design of this desulfurizing agent takes into account efficiency, ease of operation and economy, demonstrating its potential in industrial desulfurization applications.

[0084] The present invention also provides a simple calculation method and application of the complex iron content in the above-mentioned desulfurizer. This complex iron presents a reddish-brown color that is sensitive to the human eye, and at the same time, the other components in the desulfurizer are colorless and will not cover up or interfere with the color of the complex iron. According to the Lambert-Beer law, in a dilute solution, the strength of a substance's absorption of light of a certain wavelength is proportional to the concentration of its solution. Since the color of a substance is closely related to its absorption of light, the color of the desulfurizer dilute solution is closely related to the concentration of the complex iron. Based on this, a dilute desulfurizer solution with a known concentration is prepared, and a dilute solution whose color changes sensitively with concentration and is easy for the human eye to recognize is selected as a reference. Using a titration method, a desulfurizer solution of unknown concentration is added dropwise into a known volume of deionized water for dilution. When the diluted solution and the reference solution have the same color, the titration is stopped. Based on the concentration value of the reference solution and the dilution ratio of the solution of unknown concentration, the concentration of the complex iron in the desulfurizer can be calculated. In the actual desulfurization application of the desulfurizer of the present invention, this simple complex iron content calculation method can be used to evaluate the loss of complex iron, replenish the lost complex iron in time, and ensure the stable progress of the desulfurization process.

[0085] Example 1:

[0086] Synthesis of colorable iron ion complexing agent:

[0087] At room temperature, 0.75 g of glycine (10 mmol) and 0.4 g of sodium hydroxide (10 mmol) were added to 5 mL of deionized water and dissolved to obtain an amino acid salt solution;

[0088] At room temperature, 1.22 g of salicylaldehyde (10 mmol) was added to 5 mL of ethanol to obtain a salicylaldehyde solution;

[0089] At room temperature, the salicylaldehyde solution was added dropwise to the amino acid salt solution at a rate of 10 mL / h, and stirred for 3 h at a stirring speed of 200 rpm;

[0090] Under ice-water bath, 0.454 g of sodium borohydride (12 mmol) was added to the above solution. After addition, the mixture was naturally returned to room temperature and stirred for 2 h at a stirring speed of 200 rpm.

[0091] The solvent was evaporated to dryness, and a mixed solvent of methanol and deionized water in a volume ratio of 9:1 was added for recrystallization to obtain the colorable iron ion complexing agent.

[0092] H NMR spectrum of the complexing agent of Example 1 (D2O / TMS) δ: 7.24-7.20 (m, 1H), 7.17 (d, J = 7.1 Hz, 1H), 6.74 (d, J = 8.8 Hz, 1H), 6.73-6.69 (m, 1H), 4.05 (s, 1H), 3.44 (s, 1H). IR spectrum of the complexing agent of Example 1 (KBr, cm-1 ): 3362(br), 3049(br), 2944(w), 1598(s), 1561(s), 1431(br), 1347(s), 127 1(m), 1131(m), 1080(w), 1004(s), 946(m), 880(w), 753(w), 711(w), 674(w).

[0093] Synthesis of desulfurizer:

[0094] 0.030 g of the colorable iron ion complexing agent (0.15 mmol) prepared in the previous step was dissolved in 20 mL of deionized water, and 0.012 g of ferric chloride (0.075 mmol) was added and stirred to dissolve. 0.061 g of triethylamine (0.60 mmol) was added and stirred for 0.5 h to obtain a red clear solution. Sodium carbonate was added to adjust the solution pH to 8.0, and 0.2 g of polyethylene glycol 2000 was added and stirred to obtain the desulfurizing agent.

[0095] Example 2:

[0096] Synthesis of colorable iron ion complexing agent:

[0097] 1.55 g of histidine (10 mmol) and 0.4 g of sodium hydroxide (10 mmol) were poured into 20 mL of anhydrous ethanol and dissolved to obtain an amino acid salt solution;

[0098] At room temperature, 1.22 g of salicylaldehyde (10 mmol) was added to 5 mL of ethanol to obtain a salicylaldehyde solution;

[0099] At room temperature, the salicylaldehyde solution was added dropwise to the amino acid salt solution at a rate of 10 mL / h, and stirred for 3 h at a stirring speed of 200 rpm;

[0100] Under ice-water bath, 0.567 g of sodium borohydride (15 mmol) was added to the above solution. After addition, the mixture was naturally returned to room temperature and stirred for 2 h at a stirring speed of 200 rpm.

[0101] The solvent was evaporated to dryness, and a mixed solvent of methanol and deionized water in a volume ratio of 9:1 was added for recrystallization to obtain the colorable iron ion complexing agent.

[0102] H NMR spectrum of the complexing agent of Example 2 (D2O / TMS) δ: 7.64 (s, 1H), 7.19 (t, J = 7.8 Hz, 1H), 7.11 (d, J = 6.8 Hz, 1H), 6.91 (s, 1H), 6.80 (t, J = 7.5 Hz, 1H), 6.73 (d, J = 8.1 Hz, 1H), 4.03 (d, J = 13.6 Hz, 1H), 3.79 (d, J = 13.6 Hz, 1H), 3.52-3.48 (m, 1H), 3.05-3.01 (m, 1H), 2.89 (dd, J = 15.1, 8.4 Hz, 1H). IR spectrum of the complexing agent of Example 2 (KBr, cm -1 ): 3430(br), 3117(br), 3016(m), 2897(m), 2731(m), 2627(m), 1603(s), 1603(s), 1460(s), 1409(m), 1381(m), 1347(m), 1332(m), 1288(m), 12 75(m),1233(w),1206(w),1154(w),1117(w),1093(w),1036(w),1001( w),979(w),866(w),851(w),827(m),762(w),757(s),684(w),657(w).

[0103] Synthesis of desulfurizer:

[0104] Dissolve 0.042 g of the colorable iron ion complexing agent (0.15 mmol) prepared in the previous step in 20 mL of deionized water, add 0.012 g of ferric chloride (0.075 mmol) and stir to dissolve. Add 0.061 g of triethylamine (0.60 mmol) and stir for 1 hour to obtain a red clear solution. Add sodium carbonate to adjust the solution pH to 8.0, add 0.2 g of polyethylene glycol 2000, and stir evenly to obtain the desulfurizer.

[0105] Figure 1 This is a physical picture of the diluted solution of the desulfurizer in Example 2.

[0106] Example 3:

[0107] The calculation method of the complex iron content of the desulfurizer of the present invention is as follows: Taking the desulfurizer of Example 2 as an example, first, a dilute solution of a known concentration is prepared, such as Figure 1 As shown in the figure, the complex iron concentration (mol / L) of the solution in the corresponding sample bottles from left to right is 3.75×10 -5 , 1.125×10 -4 , 2.25×10 -4 , 3.75×10 -4 , 1.25×10-3 As the concentration of complex iron increases, the color of the solution changes from colorless to reddish brown, and the color of the solution gradually deepens. -5 (colorless) increased to 1.125×10 -4 (light red), the solution color changes most obviously and is easy for the human eye to identify, while the concentration increases the least. This is the sensitive change of solution color with concentration. Taking this range as the dilution end point, the error is minimized. Using the solution in sample bottle No. 2 as a reference, the desulfurizer solution of unknown concentration is slowly added to 100mL of deionized water by titration. When the diluted solution suddenly changes from colorless to light red and the solution color is consistent with the solution in sample bottle No. 2, stop. According to the concentration value of solution No. 2, 1.125×10 -4 The concentration of complexed iron in the unknown desulfurizer can be calculated by measuring the dilution ratio of M and the unknown desulfurizer. This method is simple to operate and does not require sophisticated instruments, making it easy to promote in practical applications.

[0108] Test on the effect of desulfurizer in removing hydrogen sulfide gas:

[0109] The desulfurization process was evaluated by introducing simulated waste gas (containing hydrogen sulfide) and air (used to oxidize ferrous iron) into the desulfurizer solution. The specific process parameters were as follows: a simulated waste gas flow rate of 20 mL / min, the hydrogen sulfide content in the simulated waste gas as shown in Table 1, a desulfurizer solution volume of 20 mL, and an air flow rate of 20 mL / min. The hydrogen sulfide removal effect and the iron content in the desulfurized solution calculated using the method of Example 3 are shown in Table 1.

[0110] Table 1: Desulfurization performance of desulfurizer

[0111]

[0112]

[0113] As shown in the table above, the complex iron desulfurizer of the present invention exhibits excellent stability during use, a hydrogen sulfide removal rate of 99%, and hydrogen sulfide emissions within a safe range (<10 ppm). The color development properties of the complex iron allow calculation of iron loss in the desulfurizer, and due to the excellent stability of the complex iron, iron loss is minimal.

[0114] The present invention proposes a class of colorable iron ion complexing agents with several significant advantages that can meet practical needs. First, the complexing agent molecules contain a variety of coordination groups such as phenolic hydroxyl groups, secondary amines, carboxyl groups, and imidazole groups, which can form stable water-soluble complexes with iron ions and exhibit a high hydrogen sulfide removal rate. Second, the desulfurizer prepared with this complexing agent has a reddish-brown color that is sensitive to the human eye. The color of its solution changes color sensitively with the concentration of complexed iron, and the complexed iron content can be calculated. The operation is simple and does not require precision instruments. The complexed iron lost during the desulfurization process can be replenished in a timely and convenient manner, ensuring the stability and durability of the desulfurization effect.

[0115] The raw materials such as salicylaldehyde and amino acid used in the synthesis of the complexing agent involved in this invention are widely available, cheap and easy to obtain, and can be produced on a large scale.

[0116] In summary, the present invention is significantly superior in removing hydrogen sulfide gas. First, the complex iron prepared by the complexing agent provided by the present invention has a stable structure, good water solubility, and a high hydrogen sulfide removal rate. At the same time, the color-developing properties of the complexing agent on iron are utilized, and a titration method is adopted to calculate the complex iron content. The operation is convenient, and no precision instrument is required. The complex iron lost during the actual hydrogen sulfide removal process can be replenished in time, maintaining the efficiency and durability of the desulfurization process. The complexing agent is low in cost and can be produced on a large scale. Therefore, the complexing agent of the present invention can meet actual needs and has brought important progress to the field of hydrogen sulfide removal.

[0117] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A complexing agent for iron ions that can develop color, characterized in that: The general chemical structure is as follows: In the general formula: R1 is Na or K; R2 is one of the following substituted atoms or substituents: H-CH3HOCH2NH2COCH2CH2-CH3CHOH- 2. The method for synthesizing the colorable complexing agent of iron ions according to claim 1, wherein: The steps include: (1) dissolving an amino acid and a base in an equimolar ratio in a polar solvent to form an amino acid salt solution; (2) dissolving salicylaldehyde in a polar solvent to obtain a salicylaldehyde solution; (3) dripping the salicylaldehyde solution into the amino acid salt solution; (4) adding sodium borohydride; (5) Evaporate the solvent and recrystallize.

3. The method for synthesizing the colorable complexing agent of iron ions according to claim 2, characterized in that: The molar ratio of salicylaldehyde to amino acid is 0.9-1.

2.

4. The method for synthesizing a colorable complexing agent for iron ions according to claim 2, wherein: The molar ratio of sodium borohydride to salicylaldehyde is 1-3; In step (1), the mass ratio of amino acid to polar solvent is 0.001-2; In the step (2), the mass ratio of salicylaldehyde to the polar solvent is 0.001-2.

5. The method for synthesizing a colorable iron ion complexing agent according to claim 2, wherein: The amino acid is one of glycine, alanine, serine, glutamine, threonine, tyrosine and histidine.

6. The method for synthesizing the colorable iron ion complexing agent according to claim 2, wherein: The alkali is sodium hydroxide or potassium hydroxide.

7. The method for synthesizing the colorable complexing agent of iron ions according to claim 2, characterized in that: The polar solvent is one of ethanol, methanol and water or a mixture thereof.

8. A desulfurizing agent, characterized in that: The composition includes deionized water, soluble iron salt, the complexing agent of colorable iron ions according to claim 1, triethylamine, inorganic base, and defoaming agent; The soluble iron salt is ferric chloride, ferric sulfate or ferric nitrate, which accounts for 0.01wt%-2.5wt% of the mass fraction of the desulfurizer; The molar ratio of the colorable iron ion complexing agent to the soluble iron salt is (1-50):1; The molar ratio of the triethylamine to the colorable iron ion complexing agent is (1-10):1; The inorganic base is sodium carbonate and / or potassium carbonate; The defoaming agent is polyethylene glycol, with an average molecular weight ranging from 400 to 4000, and accounting for 1 wt% to 3 wt% of the mass fraction of the desulfurizer.

9. The method for preparing a desulfurizing agent according to claim 8, wherein: The steps include: (1) dissolving the colorable iron ion complexing agent in deionized water, adding a soluble iron salt, stirring to dissolve, dropping triethylamine, and stirring for 5-30 minutes to form a complex iron aqueous solution; (2) Add a defoaming agent to the above complex iron aqueous solution and adjust the pH value of the solution to 7-10 with an inorganic base.

10. Use of the desulfurizing agent according to claim 8 in a simple method for calculating complex iron content.

Images