A method for treating chlorine-containing wastewater based on particle encapsulation

Abstract

This invention discloses a method for treating chlorinated wastewater based on particle encapsulation, belonging to the field of wastewater treatment technology. The method involves mixing sodium alginate and chitosan solid powders to prepare an aqueous solution. Magnesium acetate and magnesium nitrate are added to the chlorinated wastewater. An interfacial polymerization reaction is initiated by dropwise addition of the sodium alginate / chitosan aqueous solution, forming solid particles that encapsulate chloride ions, effectively reducing the chloride ion concentration. For wastewater with chloride ion concentrations as high as 10,000 to 50,000 mg / L, the final residual chloride ion concentration is only about 2,000 mg / L. This provides a new approach and method for industrial treatment of chlorinated wastewater and has very broad application prospects in environmental protection.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a method for treating chlorine-containing wastewater based on particle encapsulation. Background Technology

[0002] Many industrial processes, such as petrochemicals, fertilizers, papermaking, and printing and dyeing, generate chlorine-containing wastewater. Chlorinated fertilizers and pesticides used in agricultural production can also enter farmland drainage systems, forming chlorine-containing wastewater. Chloride in this wastewater degrades water quality and damages ecosystems. It can also cause toxic reactions in fish and other aquatic organisms, impacting biodiversity. Long-term exposure to high concentrations of chlorine-containing wastewater can cause irritation, corrosion, and poisoning in humans, leading to damage to skin, eyes, and other tissues, and may even be carcinogenic.

[0003] Currently, there are two main methods for treating chlorine-containing wastewater: physical evaporation crystallization, which removes chloride ions through physical evaporation and recrystallization, but the energy cost is too high, limiting its large-scale application; and membrane separation, which uses membrane filtration technology to separate chlorides from wastewater, but the investment cost of membrane separation equipment is high, and the membrane has a limited lifespan.

[0004] Current dechlorination technologies for water all have their own shortcomings, making it difficult to achieve large-scale, low-cost dechlorination. Therefore, finding an economical, inexpensive, and industrially scalable dechlorination method is one of the key scientific and technological problems that urgently need to be solved. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide a method for treating chlorine-containing wastewater based on particle encapsulation, so as to solve the technical problems of high cost and uncontrollable dechlorination effect of existing treatment methods.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] This invention discloses a method for treating chlorine-containing wastewater based on particle encapsulation, comprising the following steps:

[0008] S1: Adjust the pH value of the chlorine-containing wastewater and the temperature of the prepared sodium alginate / chitosan aqueous solution; then determine the amount of sodium alginate / chitosan aqueous solution to be used based on the required amount of chlorine removal from the chlorine-containing wastewater;

[0009] S2: Magnesium acetate, magnesium nitrate and sodium alginate / chitosan aqueous solution are added sequentially to chlorine-containing wastewater to carry out the reaction. After the reaction is completed, solid particles are obtained and the solid particles are separated from the chlorine-containing wastewater.

[0010] S3: Repeat the operation of S2 until no more solid particles are produced, and the treated wastewater is obtained.

[0011] Further, in S1, the preparation method of the sodium alginate / chitosan aqueous solution is as follows: sodium alginate, chitosan solid powder and water are mixed and stirred to obtain sodium alginate / chitosan aqueous solution; the mass ratio of sodium alginate and chitosan is 1:1; the ratio of the total amount of sodium alginate and chitosan to the amount of water is (3-7) g: (100-150) mL; the stirring intensity is 500-900 rpm.

[0012] Furthermore, in S1, the pH of the chlorine wastewater is adjusted to 2.8–5.5; the temperature of the sodium alginate / chitosan aqueous solution is adjusted to 60–70°C.

[0013] Further, in S1, determining the dosage of sodium alginate / chitosan aqueous solution based on the required chlorine removal amount from the chlorine-containing wastewater includes the following steps:

[0014] When treating 50 mL of chlorine-containing wastewater, the sodium alginate / chitosan aqueous solution is added intermittently in several drops. The material model for each drop of 10 mL of the sodium alginate / chitosan aqueous solution is shown in the following formula:

[0015] y = y1 * exp^[-0.154 * (x / 10)];

[0016] Where: y is the chloride ion concentration of the treated wastewater, mg / L; y1 is the initial chloride ion concentration of the chlorine-containing wastewater, mg / L; x is the total volume of sodium alginate / chitosan aqueous solution, mL;

[0017] When treating 50 mL of chlorine-containing wastewater, the sodium alginate / chitosan aqueous solution is added intermittently in several drops. The material model for each drop of 20 mL of the sodium alginate / chitosan aqueous solution is shown in the following formula:

[0018] y = y1 * exp^[-0.254 * (x / 20)];

[0019] Where: y is the chloride ion concentration of the treated wastewater, mg / L; y1 is the initial chloride ion concentration of the chlorine-containing wastewater, mg / L; and x is the total volume of sodium alginate / chitosan aqueous solution, mL.

[0020] Furthermore, in S2, the sodium alginate / chitosan aqueous solution is added to the chlorine-containing wastewater in an intermittent, multi-drip manner; the relationship between the amount of sodium alginate / chitosan aqueous solution added in a single drip, the total amount of sodium alginate / chitosan aqueous solution added, and the total number of drips of sodium alginate / chitosan aqueous solution is shown in the following formula:

[0021] b = 17.307 * exp^(-0.035a);

[0022] x = a * 17.307 * exp^(-0.035a);

[0023] Where: a is the volume of sodium alginate / chitosan aqueous solution added in a single drop, in mL; b is the total number of drops of sodium alginate / chitosan aqueous solution; and x is the total volume of sodium alginate / chitosan aqueous solution used, in mL.

[0024] Furthermore, the volume ratio of the sodium alginate / chitosan aqueous solution added in a single drip to the volume of chlorine-containing wastewater is 1:(2.5-5); the dripping rate of the sodium alginate / chitosan aqueous solution is 0.5-0.8 mL / min.

[0025] Furthermore, in S2, the sodium alginate / chitosan aqueous solution is allowed to stand for 3-4 hours before being added to form a homogeneous state; in S2, the chloride ion concentration in the chlorine-containing wastewater is 10000-50000 mg / L, and the magnesium ion concentration is 2000 mg / L-10000 mg / L.

[0026] Furthermore, in S2, the mass ratio of magnesium acetate to magnesium nitrate is 1.5:1; the mass ratio of the total mass of magnesium acetate and magnesium nitrate to the mass of chloride ions in the chlorine-containing wastewater is 2:1.

[0027] Furthermore, in S2, the reaction time is 1 to 1.5 hours; the solid particles are spherical particles with a diameter of 2 to 3 mm; and the separation is performed by filtration to separate the solid and liquid components.

[0028] Furthermore, in S3, the chloride ion concentration in the treated wastewater is 2000–3000 mg / L; the magnesium ion concentration is 700–900 mg / L.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] This invention discloses a method for treating chlorinated wastewater based on particle encapsulation. Sodium alginate and chitosan solid powder are mixed and prepared into an aqueous solution. Magnesium acetate and magnesium nitrate are added to the chlorinated wastewater. An interfacial polymerization reaction is initiated by dropwise addition of the sodium alginate / chitosan aqueous solution, forming solid particles that encapsulate chloride ions. After solid-liquid separation, chlorination is achieved. The invention also demonstrates the controllability of the chlorination process based on the model described. For large volumes of wastewater, a small dosage ratio and multiple batches of treatment can be used to save on equipment expansion costs, while for small volumes of wastewater, a large dosage ratio and fewer batches can be used to save on treatment time. For wastewater with chloride ion concentrations as high as 10,000 to 50,000 mg / L, the final residual chloride ion concentration is only about 2,000 mg / L. Furthermore, the method operates under normal temperature and pressure, and the reagents used are environmentally friendly, readily available, and low-cost. This provides a new approach and method for industrial treatment of chlorinated wastewater and has a very broad application prospect in environmental protection. Attached Figure Description

[0031] Figure 1 The morphology of the formed solid particles is shown in the diagram.

[0032] Where: a- solid particles immediately after separation; b- diameter of solid particles before drying; c- diameter of solid particles after drying;

[0033] Figure 2 A schematic diagram showing the magnesium ion removal effect before and after chlorine-containing wastewater treatment;

[0034] Figure 3 This is a schematic diagram showing the effect of chloride ion removal before and after the treatment of chlorine-containing wastewater. Detailed Implementation

[0035] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0036] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0037] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0038] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0039] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0040] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0041] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0042] Example 1

[0043] A method for treating chlorine-containing wastewater based on particle encapsulation includes the following steps:

[0044] S1: At room temperature and normal pressure, place a 300mL beaker on a stirrer, add 100mL of ultrapure water, 1.500g of sodium alginate, and 1.500g of chitosan solid powder. Adjust the stirrer temperature to 60℃ and the stirring intensity to 600rpm. After stirring, let it stand at room temperature for 3h to dissolve the sodium alginate / chitosan mixture and obtain a homogeneous sodium alginate / chitosan aqueous solution.

[0045] Under normal room temperature and pressure conditions, 50 mL of sodium chloride wastewater with a chloride ion concentration of 52540 mg / L was added to a 300 mL beaker, the pH value was adjusted to 3.0, and the sodium alginate / chitosan aqueous solution was heated to 60℃.

[0046] S2: The total volume of sodium alginate / chitosan aqueous solution was calculated to be 120 mL. 120 mL of heated sodium alginate / chitosan aqueous solution was poured into a 200 mL beaker. Then, 3.152 g of magnesium acetate and 2.101 g of magnesium nitrate were added to the sodium chloride wastewater in sequence. Then, 120 mL of sodium alginate / chitosan aqueous solution was added dropwise to the sodium chloride wastewater in batches at a flow rate of 0.8 mL / min for 1 to 1.5 h. Each batch of sodium alginate / chitosan aqueous solution was added dropwise and allowed to stand for 1 h. After filtration, another 10 mL of sodium alginate / chitosan aqueous solution was added dropwise to the filtrate.

[0047] S3: Repeat the above operation until no more solid particles are produced, and the treated wastewater is obtained; the concentration of residual chloride ions in the treated wastewater is measured to be 2800 mg / L and the concentration of magnesium ions is 781 mg / L.

[0048] Example 2

[0049] A method for treating chlorine-containing wastewater based on particle encapsulation includes the following steps:

[0050] S1: At room temperature and normal pressure, place a 300mL beaker on a stirrer, add 100mL of ultrapure water, 1.500g of sodium alginate, and 1.500g of chitosan solid powder. Adjust the stirrer temperature to 60℃ and the stirring intensity to 600rpm. After stirring, let it stand at room temperature for 3h to dissolve the sodium alginate / chitosan mixture and obtain a homogeneous sodium alginate / chitosan aqueous solution.

[0051] Under normal room temperature and pressure conditions, 50 mL of sodium chloride wastewater with a chloride ion concentration of 52540 mg / L was added to a 300 mL beaker, the pH value was adjusted to 3.0, and the sodium alginate / chitosan aqueous solution was heated to 60℃.

[0052] S2: The total volume of sodium alginate / chitosan aqueous solution was calculated to be 120 mL. 120 mL of heated sodium alginate / chitosan aqueous solution was poured into a 200 mL beaker. Then, 3.152 g of magnesium acetate and 2.101 g of magnesium nitrate were added to the sodium chloride wastewater in sequence. Then, 120 mL of sodium alginate / chitosan aqueous solution was added dropwise to the sodium chloride wastewater in batches at a flow rate of 0.8 mL / min for 1 to 1.5 h. Each batch of sodium alginate / chitosan aqueous solution was added dropwise and allowed to stand for 1 h. After filtration, another 20 mL of sodium alginate / chitosan aqueous solution was added dropwise to the filtrate.

[0053] S3: Repeat the above operation until no more solid particles are produced, and the treated wastewater is obtained; the concentration of residual chloride ions in the treated wastewater is measured to be 2700 mg / L and the concentration of magnesium ions is 701 mg / L.

[0054] Example 3

[0055] A method for treating chlorine-containing wastewater based on particle encapsulation includes the following steps:

[0056] S1: At room temperature and normal pressure, place a 300mL beaker on a stirrer, add 100mL of ultrapure water, 1.500g of sodium alginate, and 1.500g of chitosan solid powder. Adjust the stirrer temperature to 60℃ and the stirring intensity to 600rpm. After stirring, let it stand at room temperature for 3h to dissolve the sodium alginate / chitosan mixture and obtain a homogeneous sodium alginate / chitosan aqueous solution.

[0057] Under normal room temperature and pressure conditions, 50 mL of sodium chloride wastewater with a chloride ion concentration of 40000 mg / L was added to a 300 mL beaker, the pH value was adjusted to 3.0, and the sodium alginate / chitosan aqueous solution was heated to 60℃.

[0058] S2: The total volume of sodium alginate / chitosan aqueous solution was calculated to be 137 mL. 137 mL of heated sodium alginate / chitosan aqueous solution was poured into a 200 mL beaker. Then, 0.24 g of magnesium acetate and 0.16 g of magnesium nitrate were added to the sodium chloride wastewater in sequence. Then, 137 mL of sodium alginate / chitosan aqueous solution was added dropwise to the sodium chloride wastewater in batches at a flow rate of 0.8 mL / min for 1 to 1.5 h. Each batch of sodium alginate / chitosan aqueous solution was added dropwise and allowed to stand for 1 h. After filtration, another 12.5 mL of sodium alginate / chitosan aqueous solution was added dropwise to the filtrate.

[0059] S3: Repeat the above operation until no more solid particles are produced, and the treated wastewater is obtained; the concentration of residual chloride ions in the treated wastewater is measured to be 2100 mg / L and the concentration of magnesium ions is 730 mg / L.

[0060] Example 4

[0061] A method for treating chlorine-containing wastewater based on particle encapsulation includes the following steps:

[0062] S1: At room temperature and normal pressure, place a 300mL beaker on a stirrer, add 100mL of ultrapure water, 1.500g of sodium alginate, and 1.500g of chitosan solid powder. Adjust the stirrer temperature to 60℃ and the stirring intensity to 600rpm. After stirring, let it stand at room temperature for 3h to dissolve the sodium alginate / chitosan mixture and obtain a homogeneous sodium alginate / chitosan aqueous solution.

[0063] Under normal room temperature and pressure conditions, 50 mL of sodium chloride wastewater with a chloride ion concentration of 30000 mg / L was added to a 300 mL beaker, the pH value was adjusted to 3.0, and the sodium alginate / chitosan aqueous solution was heated to 60℃.

[0064] S2: The total volume of sodium alginate / chitosan aqueous solution was calculated to be 150 mL. 150 mL of heated sodium alginate / chitosan aqueous solution was poured into a 200 mL beaker. Then, 0.18 g of magnesium acetate and 0.12 g of magnesium nitrate were added to the sodium chloride wastewater in sequence. Then, 150 mL of sodium alginate / chitosan aqueous solution was added dropwise to the sodium chloride wastewater in batches at a flow rate of 0.8 mL / min for 1 to 1.5 h. Each batch of sodium alginate / chitosan aqueous solution was added dropwise and allowed to stand for 1 h. After filtration, another 14.3 mL of sodium alginate / chitosan aqueous solution was added dropwise to the filtrate.

[0065] S3: Repeat the above operation until no more solid particles are produced, and the treated wastewater is obtained; the concentration of residual chloride ions in the treated wastewater is measured to be 2200 mg / L and the concentration of magnesium ions is 725 mg / L.

[0066] Figure 1 The image shows the morphology of the solid particles formed. The top image shows the solid particles immediately after separation, the bottom left image shows the diameter of the solid particles before drying, and the bottom right image shows the diameter of the solid particles after drying. The morphology images show that the solid particles are relatively clean and free of impurities, with well-preserved and uniform spherical shapes, indicating very convenient and complete solid-liquid separation.

[0067] Figure 2 The diagram shows the magnesium ion removal effect before and after the treatment of chlorine-containing wastewater. As can be seen from the diagram, although magnesium ion impurities are introduced in the process of removing chlorine ions, they are eventually removed along with the solid particles, thus restoring the water quality well.

[0068] Figure 3 The diagram shows the chloride ion removal effect before and after the treatment of chlorine-containing wastewater. As can be seen from the diagram, the chloride ion removal effect is very good, reaching more than 90%.

[0069] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for treating chlorine-containing wastewater based on particle encapsulation, characterized in that, Includes the following steps: S1: Adjust the pH value of the chlorine-containing wastewater and the temperature of the prepared sodium alginate / chitosan aqueous solution; then determine the amount of sodium alginate / chitosan aqueous solution to be used based on the required amount of chlorine removal from the chlorine-containing wastewater; S2: Magnesium acetate, magnesium nitrate and sodium alginate / chitosan aqueous solution are added sequentially to chlorine-containing wastewater to carry out the reaction. After the reaction is completed, solid particles are obtained and the solid particles are separated from the wastewater. S3: Repeat the operation of S2 until no more solid particles are produced, and the treated wastewater is obtained. In S1, the pH of the chlorine-containing wastewater is adjusted to 2.8~5.5; the temperature of the sodium alginate / chitosan aqueous solution is adjusted to 60~70℃. In S2, the chloride ion concentration in the chlorine-containing wastewater is 10,000~50,000 mg / L, and the magnesium ion concentration is 2,000 mg / L~10,000 mg / L.

2. The method for treating chlorine-containing wastewater based on particle encapsulation according to claim 1, characterized in that, In S1, the preparation method of the sodium alginate / chitosan aqueous solution is as follows: sodium alginate, chitosan solid powder and water are mixed and stirred to obtain sodium alginate / chitosan aqueous solution; the mass ratio of sodium alginate and chitosan is 1:1; the ratio of the total amount of sodium alginate and chitosan to the amount of water is (3~7) g: (100~150) mL; the stirring intensity is 500~900 rpm.

3. The method for treating chlorine-containing wastewater based on particle encapsulation according to claim 1, characterized in that, In S1, determining the dosage of sodium alginate / chitosan aqueous solution based on the required chlorine removal amount from the chlorine-containing wastewater includes the following steps: When treating 50 mL of chlorine-containing wastewater, the sodium alginate / chitosan aqueous solution is added intermittently in several drops. The material model for each drop of 10 mL of the sodium alginate / chitosan aqueous solution is shown in the following formula: y= *exp^[-0.154*(x / 10)]; Where: y is the chloride ion concentration of the treated wastewater, mg / L; denoted as initial chloride ion concentration in chlorinated wastewater, mg / L; x represents the total volume of sodium alginate / chitosan aqueous solution used, mL. When treating 50 mL of chlorine-containing wastewater, the sodium alginate / chitosan aqueous solution is added intermittently in several drops. The material model for each drop of 20 mL of the sodium alginate / chitosan aqueous solution is shown in the following formula: y= *exp^[-0.254*(x / 20)]; Where: y is the chloride ion concentration of the treated wastewater, mg / L; denoted as initial chloride ion concentration in chlorine-containing wastewater (mg / L); x represents the total volume of sodium alginate / chitosan aqueous solution used (mL).

4. The method for treating chlorine-containing wastewater based on particle encapsulation according to claim 3, characterized in that, In S2, the sodium alginate / chitosan aqueous solution is added to the chlorine-containing wastewater in an intermittent, multi-drip manner. The relationship between the amount of sodium alginate / chitosan aqueous solution added in a single drip, the total amount of sodium alginate / chitosan aqueous solution added, and the total number of drips is shown in the following formula: b = 17.307 * exp^(-0.035a); x = a * 17.307 * exp^(-0.035a); Where: a is the volume of sodium alginate / chitosan aqueous solution added in a single drop, in mL; b is the total number of drops of sodium alginate / chitosan aqueous solution; and x is the total volume of sodium alginate / chitosan aqueous solution used, in mL.

5. The method for treating chlorine-containing wastewater based on particle encapsulation according to claim 4, characterized in that, The volume ratio of the sodium alginate / chitosan aqueous solution added in a single drip to the volume of chlorine-containing wastewater is 1:(2.5~5); the dripping rate of the sodium alginate / chitosan aqueous solution is 0.5~0.8 mL / min.

6. The method for treating chlorine-containing wastewater based on particle encapsulation according to claim 1, characterized in that, In S2, the sodium alginate / chitosan aqueous solution is allowed to stand for 3-4 hours before being added to form a homogeneous state.

7. The method for treating chlorine-containing wastewater based on particle encapsulation according to claim 1, characterized in that, In S2, the mass ratio of magnesium acetate to magnesium nitrate is 1.5:1; the mass ratio of the total mass of magnesium acetate and magnesium nitrate to the mass of chloride ions in the chlorine-containing wastewater is 2:

1.

8. The method for treating chlorine-containing wastewater based on particle encapsulation according to claim 1, characterized in that, In S2, the reaction time is 1 to 1.5 hours; the solid particles are spherical particles with a diameter of 2 to 3 mm; the separation is performed by filtration to separate the solid and liquid.

9. A method for treating chlorine-containing wastewater based on particle encapsulation according to claim 1, characterized in that, In S3, the concentration of chloride ions in the treated wastewater is 2000~3000 mg / L; the concentration of magnesium ions is 700~900 mg / L.

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