A natural organic polymeric flocculant and its preparation method

Abstract

This invention discloses a natural organic polymeric flocculant and its preparation method. In this invention, zinc acetate and urea generate basic zinc carbonate. During high-temperature pyrolysis, basic zinc carbonate produces CO2, water vapor, and NH3. CO2 and water vapor enrich the pore structure of cassava residue biochar, while NH3 facilitates the generation of basic functional groups on the biochar surface, promoting subsequent reactions. Subsequently, active groups are introduced onto the surface of the cassava residue biochar through grafting modification. Utilizing the abundant amine groups in the polyethyleneimine chain, the flocculant's adsorption capacity for heavy metal ions is improved. Furthermore, the branched network structure obtained through grafting significantly enhances the flocculation effect. Hydroxypropyl distarch phosphate is introduced into the polymeric flocculant. Hydroxypropyl distarch phosphate has excellent adhesive bridging properties, increasing the molecular chain size formed by the flocculant and greatly improving its flocculation effect.

Description

Technical Field

[0001] This invention relates to the field of flocculant preparation technology, specifically to a natural organic polymeric flocculant and its preparation method. Background Technology

[0002] Flocculation sedimentation is one of the main methods used for sludge dewatering. It achieves rapid sludge-water separation by rapidly destabilizing and settling sludge particles through bridging, adsorption, and association.

[0003] Inorganic flocculants can effectively remove most suspended dyes, disperse dyes, vat dyes, sulfur dyes, and some direct dyes with larger molecular weights from water-soluble dyes in dyeing and printing wastewater. However, their removal efficiency is lower for water-soluble dyes such as reactive dyes, acid dyes, and metal complex dyes. Furthermore, inorganic flocculants require large dosages and produce a lot of sludge in wastewater treatment, and their treatment effect is easily affected by changes in water quality, which greatly limits their application scope.

[0004] In recent years, with the continuous development of materials science and polymerization technology, more and more researchers have begun to focus on the preparation and application of organic polymer flocculants. For example, organic polymer flocculants containing multiple functional groups are prepared by polymerization reactions. These flocculants have better adsorption performance and flocculation effect and are suitable for various water treatment fields. However, organic polymer flocculants also have various defects, such as light flocs, high treatment costs, and strong selectivity in the complexation reaction between cationic surfactants and dye molecules in dyeing and printing wastewater.

[0005] Inorganic-organic hybrid polymeric flocculants combine the characteristics of organic polymers and inorganic substances, exhibiting excellent flocculation performance and potential application value. In recent years, researchers have conducted extensive research on the design and preparation of inorganic-organic hybrid polymeric flocculants, preparing hybrid flocculants with superior performance by rationally designing the ratio and structure of inorganic and organic components. In addition, researchers have studied the removal effect of hybrid flocculants on pollutants in different water bodies and found that they have good application prospects. Chinese patent document CN201510960560.6 discloses a method for preparing an organic-inorganic hybrid flocculant. The technical solution is as follows: acrylamide and purple clay powder with a particle size range of 125-150 μm are weighed into a reaction vessel, distilled water is added, the temperature is raised to 75-90℃, potassium persulfate is added and stirred, and the reaction is carried out at 75-90℃ for 1.5-2.5 h. Camellia oleifera fruit shell extract is added into the reaction vessel and stirred at 75-90℃ for 1-3 h. A 10% sodium hydroxide solution is added to the reaction vessel and stirred at 75-90℃ for 1-3 h. The pH value is adjusted to 7 by adding acid, and the mixture is dried and pulverized to obtain Camellia oleifera fruit shell extract flocculant. The prepared flocculant has the advantages of low cost, easy degradation and safe use, but its removal effect on pollutants in water bodies still needs to be further improved. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of this invention is to provide a natural organic polymer flocculant and its preparation method, wherein the prepared flocculant can quickly remove pollutants from water.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for preparing a natural organic polymeric flocculant includes the following steps:

[0009] S1. Add cassava residue to an aqueous solution containing zinc acetate and urea, soak, dry, then pyrolyze at high temperature, grind and sieve to obtain cassava residue biochar.

[0010] S2. Disperse cassava residue biochar in deionized water, then add polyethyleneimine and epichlorohydrin, heat and stir to react. After the reaction is complete, filter, wash and dry the reaction product to obtain modified biochar.

[0011] S3. Disperse the modified biochar in deionized water, add hydroxypropyl distarch phosphate, stir evenly, then add polyaluminum chloride aqueous solution, heat and stir, and then freeze dry to obtain the natural organic polymer flocculant.

[0012] Preferably, in step S1, the mass-to-volume ratio of cassava residue to aqueous solution is 1g:10-20mL.

[0013] Preferably, in step S1, the concentration of zinc acetate is 0.1-0.2 mol / L and the concentration of urea is 0.1-0.2 mol / L.

[0014] Preferably, in step S1, the high-temperature pyrolysis temperature is 400-500℃ and the high-temperature pyrolysis time is 2-3h.

[0015] Preferably, in step S2, the mass ratio of cassava residue biochar, polyethyleneimine, and epichlorohydrin is 10-15:4-8:3-5.

[0016] Preferably, in step S2, the heating and stirring reaction temperature is 60-80℃, and the heating and stirring reaction time is 3-5h.

[0017] Preferably, in step S3, the mass ratio of modified biochar, hydroxypropyl distarch phosphate, and polyaluminum chloride aqueous solution is 5-10:2-3:50-80.

[0018] Preferably, in step S3, the mass fraction of the polyaluminum chloride aqueous solution is 25-40%.

[0019] Preferably, in step S3, the heating and stirring temperature is 40-60℃, and the heating and stirring time is 0.5-2h.

[0020] The present invention also provides a natural organic polymer flocculant prepared by the above preparation method.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) In this invention, zinc acetate and urea generate basic zinc carbonate. During the high-temperature pyrolysis process, basic zinc carbonate produces CO2, water vapor and NH3. CO2 and water vapor can enrich the pore structure of cassava residue biochar, while NH3 helps to generate basic functional groups on the surface of biochar, which is beneficial to the subsequent reaction.

[0023] (2) This invention introduces active groups on the surface of cassava residue biochar through grafting modification. With the help of the abundant amine groups in the polyethyleneimine chain, the adsorption capacity of the flocculant for heavy metal ions is improved on the one hand, and the branched network structure obtained by grafting greatly improves the flocculation effect of the flocculant on the other hand.

[0024] (3) The present invention introduces hydroxypropyl distarch phosphate into the flocculant. Hydroxypropyl distarch phosphate has a good adhesive bridging effect, which increases the size of the molecular chain formed by the flocculant, thereby increasing the aggregation rate of pollutants in the wastewater and greatly improving the flocculation effect of the flocculant.

[0025] (4) This invention uses natural cassava residue as raw material and prepares a polymer flocculant through a series of processes. It can give full play to the flocculation effect of inorganic and organic materials, and has a good effect and fast sedimentation speed. Detailed Implementation

[0026] The present invention will be further described in detail below through specific preferred embodiments, but the present invention is not limited to the following embodiments.

[0027] It should be noted that, unless otherwise specified, all chemical reagents involved in this invention were purchased through commercial channels.

[0028] The polyethyleneimine used in this invention has a relative molecular mass of 3000.

[0029] Example 1

[0030] A method for preparing a natural organic polymeric flocculant includes the following steps:

[0031] S1. Add 20g of cassava residue to 200mL of an aqueous solution containing zinc acetate and urea, wherein the concentration of zinc acetate is 0.2mol / L and the concentration of urea is 0.2mol / L. Soak for 12h, dry in an oven at 60℃, and then perform high-temperature pyrolysis at 400℃ for 3h. Grind through a 100-mesh sieve to obtain cassava residue biochar.

[0032] S2. Disperse 10g of cassava residue biochar in 200mL of deionized water, then add 4g of polyethyleneimine and 3g of epichlorohydrin to it, heat and stir at 60℃ for 5h. After the reaction is completed, filter, wash and dry the reaction product to obtain modified biochar.

[0033] S3. Disperse 5g of modified biochar in 50mL of deionized water, add 3g of hydroxypropyl distarch phosphate, stir well, then add 50g of 25wt% polyaluminum chloride aqueous solution, heat and stir at 40℃ for 2h, and then freeze dry to obtain natural organic polymer flocculant.

[0034] Example 2

[0035] A method for preparing a natural organic polymeric flocculant includes the following steps:

[0036] S1. Add 20g of cassava residue to 300mL of an aqueous solution containing zinc acetate and urea, wherein the concentration of zinc acetate is 0.1mol / L and the concentration of urea is 0.1mol / L. Soak for 12h, dry in an oven at 60℃, and then perform high-temperature pyrolysis at 500℃ for 2h. Grind through a 100-mesh sieve to obtain cassava residue biochar.

[0037] S2. Disperse 15g of cassava residue biochar in 200mL of deionized water, then add 8g of polyethyleneimine and 5g of epichlorohydrin to it, heat and stir at 80℃ for 3h. After the reaction is completed, filter, wash and dry the reaction product to obtain modified biochar.

[0038] S3. Disperse 6g of modified biochar in 50mL of deionized water, add 3g of hydroxypropyl distarch phosphate, stir well, then add 60g of 25wt% polyaluminum chloride aqueous solution, heat and stir at 60℃ for 1h, and then freeze dry to obtain natural organic polymer flocculant.

[0039] Example 3

[0040] A method for preparing a natural organic polymeric flocculant includes the following steps:

[0041] S1. Add 20g of cassava residue to 400mL of an aqueous solution containing zinc acetate and urea, wherein the concentration of zinc acetate is 0.2mol / L and the concentration of urea is 0.2mol / L. Soak for 12h, dry in an oven at 60℃, and then perform high-temperature pyrolysis at 450℃ for 3h. Grind through a 100-mesh sieve to obtain cassava residue biochar.

[0042] S2. Disperse 12g of cassava residue biochar in 200mL of deionized water, then add 6g of polyethyleneimine and 4g of epichlorohydrin to it, heat and stir at 60℃ for 4h. After the reaction is completed, filter, wash and dry the reaction product to obtain modified biochar.

[0043] S3. Disperse 8g of modified biochar in 50mL of deionized water, add 2g of hydroxypropyl distarch phosphate, stir well, then add 60g of 40wt% polyaluminum chloride aqueous solution, heat and stir at 50℃ for 2h, and then freeze dry to obtain natural organic polymer flocculant.

[0044] Example 4

[0045] A method for preparing a natural organic polymeric flocculant includes the following steps:

[0046] S1. Add 20g of cassava residue to 300mL of an aqueous solution containing zinc acetate and urea, wherein the concentration of zinc acetate is 0.2mol / L and the concentration of urea is 0.2mol / L. Soak for 12h, dry in an oven at 60℃, and then perform high-temperature pyrolysis at 500℃ for 3h. Grind through a 100-mesh sieve to obtain cassava residue biochar.

[0047] S2. Disperse 14g of cassava residue biochar in 200mL of deionized water, then add 5g of polyethyleneimine and 5g of epichlorohydrin to it, heat and stir at 70℃ for 3h. After the reaction is completed, filter, wash and dry the reaction product to obtain modified biochar.

[0048] S3. Disperse 6g of modified biochar in 50mL of deionized water, add 3g of hydroxypropyl distarch phosphate, stir well, then add 80g of 25wt% polyaluminum chloride aqueous solution, heat and stir at 50℃ for 2h, and then freeze dry to obtain natural organic polymer flocculant.

[0049] Comparative Example 1

[0050] A method for preparing a natural organic polymeric flocculant includes the following steps:

[0051] S1. Dry 20g of cassava residue in an oven at 60℃, then pyrolyze it at 500℃ for 2 hours. Grind it through a 100-mesh sieve to obtain cassava residue biochar.

[0052] S2. Disperse 15g of cassava residue biochar in 200mL of deionized water, then add 8g of polyethyleneimine and 5g of epichlorohydrin to it, heat and stir at 80℃ for 3h. After the reaction is completed, filter, wash and dry the reaction product to obtain modified biochar.

[0053] S3. Disperse 6g of modified biochar in 50mL of deionized water, add 3g of hydroxypropyl distarch phosphate, stir well, then add 60g of a 25wt% polyaluminum chloride aqueous solution, heat and stir at 60℃ for 1h, and then freeze-dry to obtain the natural organic polymer flocculant Comparative Example 2.

[0054] A method for preparing a natural organic polymeric flocculant includes the following steps:

[0055] S1. Add 20g of cassava residue to 300mL of an aqueous solution containing zinc acetate and urea, wherein the concentration of zinc acetate is 0.1mol / L and the concentration of urea is 0.1mol / L. Soak for 12h, dry in an oven at 60℃, and then perform high-temperature pyrolysis at 500℃ for 2h. Grind through a 100-mesh sieve to obtain cassava residue biochar.

[0056] S2. Disperse 6g of cassava residue biochar in 50mL of deionized water, add 3g of hydroxypropyl distarch phosphate, stir well, then add 60g of 25wt% polyaluminum chloride aqueous solution, heat and stir at 60℃ for 1h, and then freeze dry to obtain a natural organic polymer flocculant.

[0057] Comparative Example 3

[0058] A method for preparing a natural organic polymeric flocculant includes the following steps:

[0059] S1. Add 20g of cassava residue to 300mL of an aqueous solution containing zinc acetate and urea, wherein the concentration of zinc acetate is 0.1mol / L and the concentration of urea is 0.1mol / L. Soak for 12h, dry in an oven at 60℃, and then perform high-temperature pyrolysis at 500℃ for 2h. Grind through a 100-mesh sieve to obtain cassava residue biochar.

[0060] S2. Disperse 15g of cassava residue biochar in 200mL of deionized water, then add 8g of polyethyleneimine and 5g of epichlorohydrin to it, heat and stir at 80℃ for 3h. After the reaction is completed, filter, wash and dry the reaction product to obtain modified biochar.

[0061] S3. Disperse 6g of modified biochar in 50mL of deionized water, then add 60g of 25wt% polyaluminum chloride aqueous solution, heat and stir at 60℃ for 1h, and then freeze dry to obtain natural organic polymer flocculant.

[0062] The flocculants prepared in Examples 1-4 and Comparative Examples 1-3 were subjected to wastewater treatment tests. The specific steps are as follows: 1000 mL of artificially simulated industrial wastewater was prepared, and Cu in the wastewater was added. 2+ and Pd 2+ The concentrations of the pollutants were all 100 mg / L, and the COD concentration was 500 mg / L. Seven 250 mL Erlenmeyer flasks were used, and 100 mL of simulated industrial wastewater was added to each flask. Then, 0.1 g of the flocculant prepared in Examples 1-4 and Comparative Examples 1-3 was added to each flask. The flocculation time was 15 min. After shaking, the concentrations of each pollutant in the solution were measured. The test was performed three times and the average value was taken to calculate the removal rate. The experimental results are shown in Table 1.

[0063] Table 1

[0064] <![CDATA[Cu 2+ Removal rate (%) <![CDATA[Pb 2+ Removal rate (%) COD removal rate (%) Example 1 98.6 97.2 91.3 Example 2 98.9 96.8 91.8 Example 3 98.2 96.5 90.6 Example 4 99.5 97.7 92.2 Comparative Example 1 72.4 75.1 68.5 Comparative Example 2 65.7 70.4 63.3 Comparative Example 3 78.6 81.3 74.9

[0065] Finally, it should be noted that the above embodiments do not limit the present invention in any way. Those skilled in the art can make modifications and improvements based on the present invention. Therefore, any modifications or improvements made without departing from the spirit of the present invention are within the scope of protection claimed by the present invention.

Claims

1. A method for preparing a natural organic polymeric flocculant, characterized in that, Includes the following steps: S1. Add cassava residue to an aqueous solution containing zinc acetate and urea, soak, dry, then pyrolyze at high temperature, grind and sieve to obtain cassava residue biochar. S2. Disperse cassava residue biochar in deionized water, then add polyethyleneimine and epichlorohydrin, heat and stir to react. After the reaction is complete, filter, wash and dry the reaction product to obtain modified biochar. S3. Disperse the modified biochar in deionized water, add hydroxypropyl distarch phosphate, stir evenly, then add polyaluminum chloride aqueous solution, heat and stir, and then freeze dry to obtain natural organic polymer flocculant. In step S3, the mass ratio of modified biochar, hydroxypropyl distarch phosphate, and polyaluminum chloride aqueous solution is 5-10:2-3:50-80. The mass fraction of the polyaluminum chloride aqueous solution is 25-40%.

2. The method for preparing the natural organic polymer flocculant according to claim 1, characterized in that, In step S1, the mass-to-volume ratio of cassava residue to aqueous solution is 1g:10-20mL.

3. The method for preparing the natural organic polymer flocculant according to claim 1, characterized in that, In step S1, the concentration of zinc acetate is 0.1-0.2 mol / L, and the concentration of urea is 0.1-0.2 mol / L.

4. The method for preparing the natural organic polymer flocculant according to claim 1, characterized in that, In step S1, the high-temperature pyrolysis temperature is 400-500℃, and the high-temperature pyrolysis time is 2-3h.

5. The method for preparing the natural organic polymer flocculant according to claim 1, characterized in that, In step S2, the mass ratio of cassava residue biochar, polyethyleneimine, and epichlorohydrin is 10-15:4-8:3-5.

6. The method for preparing the natural organic polymer flocculant according to claim 1, characterized in that, In step S2, the heating and stirring reaction temperature is 60-80℃, and the heating and stirring reaction time is 3-5h.

7. The method for preparing the natural organic polymer flocculant according to claim 1, characterized in that, In step S3, the heating and stirring temperature is 40-60℃, and the heating and stirring time is 0.5-2h.

8. The natural organic polymer flocculant prepared by the preparation method according to any one of claims 1-7.