Composite treating agent for encapsulating and curing fluorescent substance and application thereof

Abstract

The invention relates to the technical field of fine chemical engineering, in particular to a composite treatment agent for encapsulating and curing a fluorescent substance, which comprises the following raw materials in parts by mass: 300-400 parts of sodium bicarbonate, 200-300 parts of calcium chloride, 50-100 parts of a difunctional template agent and 5-10 parts of a decolorizing agent. The composite treatment agent can effectively remove heavy metal ions and fluorescent dyes in wastewater, improve water quality and the like.

Description

Technical Field

[0001] This invention relates to the field of fine chemical technology, and in particular to a composite treatment agent for encapsulating and curing fluorescent substances. Background Technology

[0002] Wastewater containing fluorescent substances, especially those containing toxic fluorescent dyes or heavy metal quantum dots, presents a challenge in treatment because these substances, while often presenting at low concentrations, are highly hazardous and stably dispersed in molecular or nanoparticle form, making them difficult to separate through conventional precipitation. Existing technologies primarily employ adsorption, membrane separation, or advanced oxidation. Adsorption methods suffer from saturation and regeneration issues; membrane separation is costly and prone to contamination; and advanced oxidation may incompletely destroy the fluorescent structure, generating unknown byproducts. In recent years, biomimetic mineralization has gained attention due to its mild conditions, stable products, and environmental friendliness. For example, templates such as polyaspartic acid are used to induce calcium carbonate deposition for the blocking of heavy metals.

[0003] However, current water treatment agents have the following problems: First, the mineralization process lacks selectivity: existing biomimetic mineralization research mostly focuses on inducing mineral deposition itself, or on blocking ionic heavy metals. There is a lack of effective methods for specifically using dissolved organic fluorescent molecules or nano-fluorescent particles as "cores" or "templates" to guide minerals to preferentially grow on or around their surface, achieving selective encapsulation. Second, the mineralization rate contradicts water quality conditions: rapid precipitation of calcium carbonate requires high Ca2+ levels. 2+ and CO3 2- The concentration and high pH are inconsistent with the conditions of many actual wastewaters. The addition of alkali may cause other pollutants to precipitate or produce sludge. Third, there is the problem of floc stability: the calcium carbonate particles formed by the floc are small and settle slowly. They are not firmly bound to fluorescent substances and may be released again in the later stage or under acidic conditions. Fourth, the cost of functional templates is high: commonly used biomimetic templates (such as peptides with specific sequences and synthetic polymers) are expensive and difficult to apply on a large scale in water treatment.

[0004] There is currently a wealth of research on industrial wastewater purification. For example, patent number CN109647353B discloses a "composite heavy metal wastewater treatment agent and its preparation method and application," which is prepared from 20-30 parts of agricultural waste, 10-30 parts of humic acid, 20-30 parts of xanthic acid-modified quartz sand, 4-6 parts of sodium alginate, 4-6 parts of chitosan, 4-10 parts of calcium thioglycolate, and 3-6 parts of calcium chloride. This treatment agent contains multiple heavy metal reactive groups, enabling efficient adsorption of multiple heavy metals simultaneously. It exhibits rapid sedimentation, high treatment efficiency, strong stability, and strong environmental tolerance, and solves the problem of difficult agricultural waste treatment, turning waste into treasure and realizing the resource utilization of agricultural waste. Under suitable conditions, the removal rate of heavy metals can reach 99%. This heavy metal treatment agent has widely available raw materials and a simple preparation process, showing promising application prospects in heavy metal treatment. However, the aforementioned patent only shows good effects on the removal of heavy metals, while its effectiveness in treating industrial wastewater containing large amounts of fluorescent agents is limited.

[0005] Therefore, it is urgent to develop a low-cost composite treatment agent that can effectively remove heavy metal ions and fluorescent dyes from wastewater. Summary of the Invention

[0006] The purpose of this invention is to provide a composite treatment agent for encapsulating and curing fluorescent substances and its application, in order to solve the problem that current water treatment agents are not effective in treating fluorescent dye wastewater.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a composite treatment agent for encapsulating and curing fluorescent substances, comprising the following raw materials in parts by weight: 300-400 parts sodium bicarbonate, 200-300 parts calcium chloride, 50-100 parts bifunctional template agent, and 5-10 parts decolorizing agent.

[0008] This application uses sodium bicarbonate, calcium chloride, bifunctional template agent and decolorizing agent as raw materials to form a composite treatment agent. This composite treatment agent can not only effectively remove heavy metal ions and particulate matter in wastewater, but also remove fluorescent dyes in wastewater. Sodium bicarbonate hydrolyzes to form a large number of carbonate ions, which undergo heterogeneous nucleation with calcium ions on the surface of the bifunctional template agent, crystallizing to form calcium carbonate, which further fixes fluorescent substances and pollutants.

[0009] In some embodiments, the composite treatment agent further includes 5 to 10 parts of flocculant.

[0010] Preferably, the raw materials of the composite treatment agent also include 7 parts of flocculant.

[0011] In some embodiments, the flocculant is cationic guar gum.

[0012] This application selects cationic guar gum as a flocculant. Its long-chain molecules connect dispersed calcium carbonate particles into large and dense flocs through cationic bridging, thereby accelerating gravity sedimentation.

[0013] In some embodiments, the preparation method of the bifunctional template agent includes the following steps: dissolving carboxymethyl chitosan in MES buffer, adding carbodiimide and N-hydroxysuccinimide, shaking at room temperature for 20-40 minutes, then adding ethanolamine phosphate, reacting at room temperature for 20-28 hours, dialyzing the reaction solution for 3 days after the reaction, and lyophilizing to obtain a white solid, i.e., the bifunctional template agent.

[0014] The bifunctional template agent of this application first activates carboxymethyl chitosan in the presence of carbodiimide and N-hydroxysuccinimide. Carbodiimide reacts with the carboxyl groups on the carboxymethyl chitosan molecular chain to generate a highly reactive O-acylisourea intermediate. Subsequently, N-hydroxysuccinimide combines with the active intermediate to form a more stable NHS ester. Then, the NHS ester undergoes a nucleophilic substitution reaction with the primary amine in ethanolamine phosphate to achieve graft modification and obtain the bifunctional template agent. The bifunctional template agent can coordinate chelate with calcium ions, and the phosphate group achieves specific affinity for fluorescent substances. For example, dyes containing hydroxyl and amino groups can be recognized and enriched through coordination bonds or hydrogen bonds. Through the above synergistic effect, mineralization precursors can be constructed on the surface of pollutants.

[0015] In some embodiments, the total mass of the carbodiimide and N-hydroxysuccinimide is 0.4 to 0.8 times the mass of carboxymethyl chitosan.

[0016] Preferably, the total mass of the carbodiimide and N-hydroxysuccinimide is 0.6 times the mass of carboxymethyl chitosan.

[0017] In some embodiments, the degree of substitution of the carboxymethyl chitosan is 0.7 to 0.9.

[0018] Preferably, the degree of substitution of the carboxymethyl chitosan is 0.8.

[0019] In some embodiments, the mass ratio of the carbodiimide to N-hydroxysuccinimide is 1:(0.5~0.7).

[0020] Preferably, the mass ratio of the carbodiimide to N-hydroxysuccinimide is 1:0.6.

[0021] In some embodiments, the amount of ethanolamine phosphate added is 0.4 to 0.8 times the mass of carboxymethyl chitosan.

[0022] Preferably, the amount of ethanolamine phosphate added is 0.6 times the mass of carboxymethyl chitosan.

[0023] In some embodiments, the decolorizing agent is activated carbon.

[0024] Another aspect of the present invention provides an application of a composite treatment agent for encapsulating and curing fluorescent substances, comprising the following steps: (1) Add bifunctional template agent to wastewater containing fluorescent substances and stir at 140-160 rpm for 10-20 min to fully disperse the bifunctional template agent; (2) Then add calcium chloride to the system in step (1), stir for 3 to 8 minutes, then add sodium bicarbonate and stir at 50 to 70 rpm for 25 to 35 minutes; (3) Add flocculant and decolorizing agent and stir at 35-45 rpm for 5-15 minutes. After the stirring is complete, let it stand to settle and filter to obtain purified water.

[0025] This application, by adding calcium chloride in stages, enables calcium ions in calcium chloride to rapidly coordinate with the bifunctional template agent after the bifunctional template agent has completely adsorbed the pollutants, thereby achieving mineralization and coating of the pollutants. At the same time, it avoids the situation where a large number of calcium ions preferentially coordinate with the bifunctional template agent and occupy its active site when calcium chloride and the bifunctional template agent are added at the same time, which would cause a sudden increase in steric hindrance, weaken the adsorption capacity of phosphate groups for fluorescent substances, and prevent the formation of mineralized precursor structures on the surface of pollutants.

[0026] Compared with the prior art, the present invention has the following beneficial effects: (1) The bifunctional template agent of the present invention can coordinate and chelate with calcium ions, and the phosphate group achieves specific affinity for fluorescent substances. In particular, dyes containing hydroxyl and amino groups can be recognized and enriched through coordination bonds or hydrogen bonds. Through the above synergistic effect, mineralization precursors can be constructed on the surface of pollutants.

[0027] (2) By adding calcium chloride in steps, the present invention can achieve mineralization and coating of pollutants by rapidly coordinating calcium ions with bifunctional template agents after the bifunctional template agent has completely adsorbed the pollutants. At the same time, it can avoid the situation where a large number of calcium ions preferentially coordinate with bifunctional template agents to occupy their active sites when calcium chloride and bifunctional template agents are added at the same time, which would cause a sudden increase in steric hindrance and weaken the adsorption capacity of phosphate groups for fluorescent substances, and at the same time, prevent the formation of mineralization precursor structures on the surface of pollutants.

[0028] (3) After the sodium bicarbonate of the present invention is hydrolyzed, a large number of carbonate ions are formed, which undergo heterogeneous nucleation with calcium ions on the surface of the bifunctional template agent, and crystallize to form calcium carbonate to further fix fluorescent substances and pollutants.

[0029] (4) The flocculant of the present invention has long-chain molecules that connect dispersed calcium carbonate particles into large and dense flocs through cationic bridging, thereby accelerating gravity sedimentation.

[0030] (5) The raw materials used in this invention are green and environmentally friendly, which can reduce pollution to the environment. Detailed Implementation

[0031] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0032] Unless otherwise specified, those skilled in the art may select from the following post-processing operations, such as "mixing," "vibration," "dialysis," "freeze-drying," "stirring," and "sedimentation," based on actual conditions, without further limitation.

[0033] Cationic guar gum was purchased from Jinan Shenghe Chemical Co., Ltd.; activated carbon was purchased from Henan Binwei Environmental Protection Technology Co., Ltd.

[0034] Preparation Example 1 The preparation method of the bifunctional template agent includes the following steps: 5g of carboxymethyl chitosan with a degree of substitution of 0.8 was dissolved in 100ml of MES buffer at pH 5.5. 2g of carbodiimide and 1.2g of N-hydroxysuccinimide were added, and the mixture was shaken at room temperature for 30 minutes. Then, 3g of ethanolamine phosphate was added, and the mixture was reacted at room temperature for 26 hours. After the reaction was completed, the reaction solution was dialyzed for 3 days and then lyophilized to obtain a white solid, which is the bifunctional template agent.

[0035] Preparation Example 2 The preparation method of the bifunctional template agent is the same as that in Preparation Example 1, except that the amount of carbodiimide is 3.1g and the amount of N-hydroxysuccinimide is 1.9g.

[0036] Preparation Example 3 The preparation method of the bifunctional template agent is the same as that in Preparation Example 1, except that the degree of substitution of carboxymethyl chitosan is 1.

[0037] Preparation Example 4 The preparation method of the bifunctional template agent is the same as that in Preparation Example 1, except that the amount of ethanolamine phosphate is 1g.

[0038] Example 1 A composite treatment agent for encapsulating and curing fluorescent substances comprises the following raw materials in parts by weight: 350 parts sodium bicarbonate, 250 parts calcium chloride, 70 parts bifunctional template agent, 7 parts cationic guar gum, and 7 parts activated carbon.

[0039] The bifunctional template agent was prepared by Preparation Example 1.

[0040] The application of composite treatment agents for encapsulating and curing fluorescent substances includes the following steps: (1) Add bifunctional template agent to wastewater containing fluorescent substances and stir at 150 rpm for 15 min to fully disperse the bifunctional template agent; (2) Then add calcium chloride to the system in step (1), stir for 5 min, then add sodium bicarbonate and stir at 60 rpm for 30 min; (3) Add cationic guar gum and activated carbon and stir at 40 rpm for 10 min. After the stirring is complete, let it stand to settle and filter to obtain purified water.

[0041] Example 2 A composite treatment agent for encapsulating and curing fluorescent substances comprises the following raw materials in parts by weight: 300 parts sodium bicarbonate, 200 parts calcium chloride, 50 parts bifunctional template agent, 5 parts cationic guar gum, and 5 parts activated carbon.

[0042] The bifunctional template agent was prepared by Preparation Example 1.

[0043] The application of composite treatment agents for encapsulating and curing fluorescent substances includes the following steps: (1) Add bifunctional template agent to wastewater containing fluorescent substances and stir at 140 rpm for 20 min to fully disperse the bifunctional template agent; (2) Then add calcium chloride to the system in step (1), stir for 8 min, then add sodium bicarbonate and stir at 50 rpm for 35 min; (3) Add activated carbon and stir at 35 rpm for 15 minutes. After the stirring is complete, let it stand to settle and filter to obtain purified water.

[0044] Example 3 A composite treatment agent for encapsulating and curing fluorescent substances comprises the following raw materials in parts by weight: 400 parts sodium bicarbonate, 300 parts calcium chloride, 100 parts bifunctional template agent, 10 parts cationic guar gum, and 10 parts activated carbon.

[0045] The bifunctional template agent was prepared by Preparation Example 1.

[0046] The application of composite treatment agents for encapsulating and curing fluorescent substances includes the following steps: (1) Add bifunctional template agent to wastewater containing fluorescent substances and stir at 160 rpm for 10 min to fully disperse the bifunctional template agent; (2) Then add calcium chloride to the system in step (1), stir for 3 min, then add sodium bicarbonate and stir at 70 rpm for 25 min; (3) Add cationic guar gum and activated carbon and stir at 45 rpm for 5 min. After the stirring is complete, let it stand to settle and filter to obtain purified water.

[0047] Example 4 A composite treatment agent for encapsulating and curing fluorescent substances comprises the following raw materials in parts by weight: 350 parts sodium bicarbonate, 250 parts calcium chloride, 70 parts bifunctional template agent, and 7 parts activated carbon.

[0048] The bifunctional template agent was prepared by Preparation Example 1.

[0049] The application of composite treatment agents for encapsulating and curing fluorescent substances includes the following steps: (1) Add bifunctional template agent to wastewater containing fluorescent substances and stir at 150 rpm for 15 min to fully disperse the bifunctional template agent; (2) Then add calcium chloride to the system in step (1), stir for 5 min, then add sodium bicarbonate and stir at 60 rpm for 30 min; (3) Add activated carbon and stir at 40 rpm for 10 min. After the stirring is complete, let it stand to settle and filter to obtain purified water.

[0050] Example 5 A composite treatment agent for encapsulating and curing fluorescent substances and its application are described. The specific implementation method is the same as in Example 1, except that the bifunctional template agent is prepared in Preparation Example 2.

[0051] Example 6 A composite treatment agent for encapsulating and curing fluorescent substances and its application are described. The specific implementation method is the same as in Example 1, except that the bifunctional template agent is prepared in Preparation Example 3.

[0052] Example 7 A composite treatment agent for encapsulating and curing fluorescent substances and its application are described. The specific implementation method is the same as in Example 1, except that the bifunctional template agent is prepared in Preparation Example 4.

[0053] Example 8 A composite treatment agent for encapsulating and curing fluorescent substances and its application are disclosed. The specific implementation method is the same as in Example 1, except that the application of the composite treatment agent for encapsulating and curing fluorescent substances includes the following steps: (1) Add calcium chloride, sodium bicarbonate and bifunctional template agent to the wastewater containing fluorescent substances at the same time, and stir at 150 rpm for 45 min to fully disperse the bifunctional template agent. (2) Add cationic guar gum and activated carbon and stir at 40 rpm for 10 min. After the stirring is complete, let it stand to settle and filter to obtain purified water.

[0054] Comparative Example 1 A composite treatment agent for encapsulating and curing fluorescent substances and its application are described. The specific implementation method is the same as in Example 1, except that sodium citrate is used as a template agent instead of a bifunctional template agent.

[0055] The purified water obtained from each embodiment and comparative example was subjected to the following performance tests: (1) pH: Tested according to GB / T6920-1986; (2) Color: The test shall be conducted in accordance with GB11903.4-1989. Color is used to evaluate the degree of removal of fluorescent substances in wastewater. (3) Chemical oxygen demand: Tested according to GB / T11914-1989; (4) Ammonia nitrogen: Tested according to HJ 535-2009; (5) Formaldehyde: Test according to HJ 601-2011.

[0056] The final discharged wastewater was detected using a PHS-3C pH meter (AHHF-160), a KHCOD-12 COD digestion device (AHHF-085), and a TU-1901 double-beam UV-Vis spectrophotometer (AHHF-004). The test results are shown in Table 1.

[0057] Table 1

[0058] According to the data in Table 1, the composite treatment agents in Examples 1-4 have a good removal effect on fluorescent dyes in wastewater, and can also effectively remove heavy metal ions and particulate pollutants from wastewater. In Example 5, due to the change in the total mass of carbodiimide and N-hydroxysuccinimide, the bifunctional template agent structure has defects, narrowing or even clogging of pores, resulting in a decrease in adsorption capacity. In Example 6, due to the change in the degree of substitution of carboxymethyl chitosan, the increase in carboxymethyl groups increases the steric hindrance of the bifunctional template agent, reduces the grafting efficiency, and leads to a decrease in the water treatment capacity of the bifunctional template agent. In Example 7, due to the change in the mass ratio of ethanolamine phosphate to carboxymethyl chitosan, the excessively high negative electric field repels anionic pollutants, resulting in a decrease in the adsorption capacity of the bifunctional template agent for anionic pollutants. In Example 8, due to the simultaneous addition of calcium chloride and the bifunctional template agent to the wastewater, the adsorption capacity of the bifunctional template agent for fluorescent substances and solid particles decreased. In Comparative Example 1, due to the use of sodium citrate as a template agent instead of the bifunctional template agent, the water quality of the purified water was still poor.

[0059] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A composite treatment agent for encapsulating and curing fluorescent substances, characterized in that, It includes the following raw materials by weight: 300-400 parts sodium bicarbonate, 200-300 parts calcium chloride, 50-100 parts bifunctional template agent, and 5-10 parts decolorizing agent.

2. The composite treatment agent for encapsulating and curing fluorescent substances according to claim 1, characterized in that, The raw materials of the composite treatment agent also include 5-10 parts by weight of flocculant.

3. The composite treatment agent for encapsulating and curing fluorescent substances according to claim 2, characterized in that, The flocculant is cationic guar gum.

4. The composite treatment agent for encapsulating and curing fluorescent substances according to claim 1, characterized in that, The preparation method of the bifunctional template agent includes the following steps: dissolving carboxymethyl chitosan in MES buffer, adding carbodiimide and N-hydroxysuccinimide, shaking at room temperature for 20-40 minutes, then adding ethanolamine phosphate, reacting at room temperature for 20-28 hours, dialyzing the reaction solution for 3 days after the reaction, and lyophilizing to obtain a white solid, i.e., the bifunctional template agent.

5. The composite treatment agent for encapsulating and curing fluorescent substances according to claim 4, characterized in that, The total mass of the carbodiimide and N-hydroxysuccinimide is 0.4 to 0.8 times the mass of carboxymethyl chitosan.

6. The composite treatment agent for encapsulating and curing fluorescent substances according to claim 4, characterized in that, The degree of substitution of the carboxymethyl chitosan is 0.7 to 0.

9.

7. The composite treatment agent for encapsulating and curing fluorescent substances according to claim 4, characterized in that, The mass ratio of the carbodiimide to N-hydroxysuccinimide is 1:(0.5~0.7).

8. The composite treatment agent for encapsulating and curing fluorescent substances according to claim 4, characterized in that, The amount of ethanolamine phosphate added is 0.4 to 0.8 times the mass of carboxymethyl chitosan.

9. The composite treatment agent for encapsulating and curing fluorescent substances according to claim 1, characterized in that, The decolorizing agent is activated carbon.

10. An application of a composite treatment agent for encapsulating and curing fluorescent substances, characterized in that, The usage steps include the following: (1) Add bifunctional template agent to wastewater containing fluorescent substances and stir at 140-160 rpm for 10-20 min to fully disperse the bifunctional template agent; (2) Then add calcium chloride to the system in step (1), stir for 3 to 8 minutes, then add sodium bicarbonate and stir at 50 to 70 rpm for 25 to 35 minutes; (3) Add flocculant and decolorizing agent and stir at 35-45 rpm for 5-15 minutes. After the stirring is complete, let it stand to settle and filter to obtain purified water.

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