A modified polyaluminum ferric chloride, its preparation method and application

Abstract

This invention discloses a modified polyaluminum ferric chloride, its preparation method, and its application, belonging to the field of water treatment technology. The preparation method includes the following steps: hyperbranched polyamide-grafted chitosan is added to an aqueous solution of isopropanol and sodium hydroxide at a temperature of 45-50°C, stirred, and kept at a constant temperature. Quaternized cationic units are added, and after the addition is complete, the temperature is raised to 60°C, and stirring is continued. After stirring, the pH is adjusted, anhydrous ethanol is added, and the mixture is washed and soaked. The resulting solid is dried to obtain cationic chitosan. The cationic chitosan is added to a polyaluminum ferric chloride dispersion, stirred and mixed at room temperature, and then aged. This invention uses inorganic flocculant polyaluminum ferric chloride and organic flocculant cationic chitosan as raw materials. The high positive charge of polyaluminum ferric chloride and the entrainment effect of cationic chitosan combine to effectively improve the decolorization and flocculation effect, greatly improving the decolorization effect and reducing the amount of reagents used.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of water treatment, and particularly relates to modified polymeric ferric aluminum chloride as well as a preparation method and application thereof. BACKGROUND

[0002] Polymeric ferric aluminum chloride (PFAC) is a kind of inorganic high-molecular composite flocculant of aluminum-iron copolymerization type, which is formed by hydrolysis and polymerization of aluminum salt and iron salt under certain conditions, and its chemical general formula is [Al2(OH) n Cl 6-n ] m ·[Fe2(OH) n Cl 6-n ]m (1≤n≤5, m≤10), which is a new type of inorganic high-molecular flocculant, and has the characteristics of both polyaluminum and polyiron, and overcomes the shortcomings of low alum flower generated by aluminum salt, poor water purification effect at low temperature and low turbidity, and high colority and equipment and pipeline corrosion caused by iron salt. The flocculant has the advantages of non-toxicity, fast reaction speed, large and compact flocculation, fast settling speed, wide pH range, small dosage and good coagulation effect. However, compared with organic flocculants, the molecular weight, particle size and flocculation bridging capacity are quite different. Single flocculant has small application range and cannot meet the use requirements.

[0003] The organic matter content in printing and dyeing wastewater is high, the colority is large, the H value is high, the composition is complex and contains toxic substances that are difficult to biodegrade, which not only causes environmental pollution, but also may enter the human body through the transmission of various food chains, thereby endangering human health. In the wastewater treatment process, there are problems such as large amount of flocculant used and low wastewater decolorization rate. SUMMARY

[0004] The purpose of the present application is to provide a modified polymeric ferric aluminum chloride and a preparation method and application thereof, so as to solve the problems of large amount of flocculant used and low wastewater decolorization rate in printing and dyeing wastewater.

[0005] The purpose of the present application can be achieved by the following technical solutions.

[0006] A preparation method of modified polymeric ferric aluminum chloride, comprising the following steps:

[0007] The hyperbranched polyamide grafted chitosan is added into isopropyl alcohol and sodium hydroxide aqueous solution, the temperature is set to 45-50 DEG C, stirring is performed for 50-60 min, the temperature is kept unchanged, quaternary ammonium cation unit is added, after the addition is completed, the temperature is increased to 60 DEG C, stirring is continuously performed for 10 h, after the stirring is completed, hydrochloric acid is added to adjust the pH value to 7, anhydrous ethanol is added, washing and soaking are performed, the obtained solid is dried, the drying temperature is less than 80 DEG C, drying is performed until the constant weight is reached, and cationic chitosan is obtained.

[0008] The cationic chitosan is added into the polymeric aluminum ferric chloride dispersion liquid, and stirred and mixed for 60-70 min at a temperature of 20-25℃, and then aged for 24 h to obtain a modified polymeric aluminum ferric chloride.

[0009] Further, the mass fraction of the sodium hydroxide aqueous solution is 40%; the ratio of the hyperbranched polyamide grafted chitosan, the quaternary ammonium cation unit, the isopropyl alcohol and the sodium hydroxide aqueous solution is 8g:8g:100mL:10g.

[0010] Further, the polymeric aluminum ferric chloride dispersion liquid is prepared by the following steps:

[0011] The polymeric aluminum chloride solution, the ferric chloride, the deionized water and the calcium chloride are mixed, stirred and reacted for 30 min at a temperature of 20℃, heated to 70℃, and continuously reacted for 4 h, and then the polymeric aluminum ferric chloride dispersion liquid is obtained. In the process of synthesizing the polymeric aluminum ferric chloride, the calcium ion is introduced, and the existence of the calcium ion participates in the copolymerization of the aluminum and iron two phases respectively, so that the free calcium ion participates in the mutual competition of the cation and the hydroxyl ion, the high molecular weight polymer is avoided to be formed, and the storage stability of the polymeric aluminum ferric chloride dispersion liquid is improved.

[0012] Further, the mass fraction of the polymeric aluminum chloride solution is 40%, and the ratio of the polymeric aluminum chloride solution, the ferric chloride, the deionized water and the calcium chloride is 100mL:35.6g:35mL:2.4g.

[0013] Further, the hyperbranched polyamide grafted chitosan is prepared by the following steps:

[0014] Under the condition of nitrogen protection, the diethylene triamine is added dropwise into the mixture of the methyl acrylate and the methanol, stirred and reacted for 4 h at a temperature of 20℃, then heated to 150℃, and continuously reacted for 4 h, and then the hyperbranched polyamide is obtained. The ratio of the diethylene triamine, the methyl acrylate and the methanol is 52mL:43mL:100mL.

[0015] The chitosan and the water are mixed and stirred, after being dispersed, the glutaraldehyde aqueous solution is added and stirred for 30 min, the hyperbranched polyamide aqueous solution is added, heated to 40℃, stirred and reacted for 1 h, and then after the reaction is completed, vacuum dried, and ground through a 100 mesh sieve to obtain the hyperbranched polyamide grafted chitosan. The mass fraction of the glutaraldehyde aqueous solution is 2%, the mass fraction of the hyperbranched polyamide aqueous solution is 50%, and the ratio of the chitosan, the water, the glutaraldehyde aqueous solution and the hyperbranched polyamide aqueous solution is 2g:100mL:100mL:5mL.

[0016] Further, the quaternary ammonium cation unit is prepared by the following steps:

[0017] N-[3-(dimethylamino)propyl]acetamide and deionized water are mixed, then hydrochloric acid is added to adjust the pH value to 7-8, and epichlorohydrin is added, and the reaction is stirred at 30 DEG C for 1h, after the reaction is completed, distilled water is added and stirred, and then separated, and extracted with water and ethyl acetate, and the obtained organic is concentrated under reduced pressure to obtain a quaternary ammonium cation unit; the amount ratio of N-[3-(dimethylamino)propyl]acetamide, epichlorohydrin and deionized water is 0.02mol:0.03mol:30mL.

[0018] Further, the amount ratio of the polymeric ferric aluminum chloride dispersion liquid and the modified chitosan is 100g:1-4g.

[0019] A modified polymeric ferric aluminum chloride, the amount ratio of the polymeric ferric aluminum chloride dispersion liquid and the modified chitosan is 100g:1-4g.

[0020] Application of a modified polymeric ferric aluminum chloride in printing and dyeing wastewater.

[0021] The beneficial effects of the present application are:

[0022] The present application uses inorganic flocculant polymeric ferric aluminum chloride and organic flocculant cationic chitosan to prepare a modified polymeric ferric aluminum chloride, the high positive charge of the polymeric ferric aluminum chloride and the entrapment effect of the cationic chitosan are combined, and the decolorization and flocculation effect is effectively improved.

[0023] In the present application, the cationic chitosan is added to introduce a hyperbranched branched structure, which improves the bridging and netting effect of the modified polymeric ferric aluminum chloride, and the quaternary ammonium ion in the hyperbranched structure increases the positive charge of the modified polymeric ferric aluminum chloride, so that the flocculation effect of the modified polymeric ferric aluminum chloride in the present application is significantly improved, and the decolorization effect is obviously better than that of the untreated sample.

[0024] The dyes used in the printing and dyeing process cannot be attached to the fabric due to various differences in structure, properties, processing methods, etc., and continue to remain in the dyeing liquid, and acid and alkali reagents are also used in the processing process, which are also one of the pollution sources of printing and dyeing wastewater, and the pH value of the water sample has a great influence on the existing treatment reagents, and the selection of the reagents will affect the treatment effect, and in the present application, the cationic chitosan with hyperbranched structure is introduced, which contains a large number of hydrophilic functional groups (quaternary ammonium salt groups, amide groups, etc.), and tends to be neutral in the water sample, and can show good stability in a large pH range. DETAILED DESCRIPTION

[0025] With reference to the drawings: the specific embodiments of the present application will be clearly and completely described, obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of the present application.

[0026] Example 1

[0027] The present embodiment provides a polyaluminum ferric chloride dispersion liquid, which is prepared by the following steps:

[0028] The polyaluminum chloride solution, ferric chloride, deionized water and calcium chloride are mixed, stirred and reacted at 20℃ for 30min, then heated to 70℃ and continued to react for 4h. After the reaction is completed, the polyaluminum ferric chloride dispersion liquid is obtained. The mass fraction of the polyaluminum chloride solution is 40%, and the amount ratio of the polyaluminum chloride solution, ferric chloride, deionized water and calcium chloride is 100mL: 35.6g: 35mL: 2.4g.

[0029] Comparative Example 1

[0030] Compared with Example 1, no calcium chloride is added, and the rest of the raw materials and the preparation process remain unchanged.

[0031] Example 2

[0032] The present embodiment provides a hyperbranched polyamide grafted chitosan, which is prepared by the following steps:

[0033] Under the condition of nitrogen protection, diethylene triamine is added dropwise into the mixture of methyl acrylate and methanol, stirred and reacted at 20℃ for 4h, then heated to 150℃ and continued to react for 4h. After the reaction is completed, the hyperbranched polyamide is obtained. The amount ratio of diethylene triamine, methyl acrylate and methanol is 52mL: 43mL: 100mL.

[0034] Chitosan and water are mixed and stirred, then glutaraldehyde aqueous solution is added and stirred for 30min, hyperbranched polyamide aqueous solution is added, heated to 40℃ and stirred for 1h. After the reaction is completed, vacuum drying is performed, and the hyperbranched polyamide grafted chitosan is obtained by grinding through a 100 mesh sieve. The mass fraction of the glutaraldehyde aqueous solution is 2%, the mass fraction of the hyperbranched polyamide aqueous solution is 50%, and the amount ratio of chitosan, water, glutaraldehyde aqueous solution and hyperbranched polyamide aqueous solution is 2g: 100mL: 100mL: 5mL.

[0035] Example 3

[0036] The present embodiment provides a quaternary ammonium cation unit, which is prepared by the following steps:

[0037] N-[3-(dimethylamino)propyl]acetamide and deionized water are mixed, hydrochloric acid is added to adjust the pH value to 7, epichlorohydrin is added, stirring is carried out at a temperature of 30℃ for 1h, after the reaction is completed, distilled water is added to stir and mix, and then it is left to stand to separate into layers, and water and ethyl acetate are used for extraction, the obtained organic matter is concentrated under reduced pressure to obtain a quaternary ammonium cation unit; the amount ratio of N-[3-(dimethylamino)propyl]acetamide, epichlorohydrin and deionized water is 0.02mol:0.03mol:30mL.

[0038] Example 4

[0039] A preparation method of modified polymeric aluminum ferric chloride, comprising the following steps:

[0040] The hyperbranched polyamide grafted chitosan prepared in Example 2 is added into isopropanol and sodium hydroxide aqueous solution, the temperature is set to 45℃, stirring is carried out for 50min, the temperature is kept unchanged, the quaternary ammonium cation unit prepared in Example 3 is added, after the addition is completed, the temperature is raised to 60℃, and stirring is continued for 10h, after the stirring is completed, hydrochloric acid is added to adjust the pH value to 7, anhydrous ethanol is added, and then the obtained solid is dried, the drying temperature is less than 80℃, and the drying is continued until the weight is constant, to obtain cationic chitosan; the mass fraction of sodium hydroxide aqueous solution is 40%; the amount ratio of hyperbranched polyamide grafted chitosan, quaternary ammonium cation unit, isopropanol and sodium hydroxide aqueous solution is 8g:8g:100mL:10g.

[0041] The cationic chitosan is added into the polymeric aluminum ferric chloride dispersion liquid prepared in Example 1, stirring is carried out at a temperature of 20℃ for 60min, and then it is left to stand for 24h, to obtain a modified polymeric aluminum ferric chloride. The amount ratio of polymeric aluminum ferric chloride dispersion liquid and modified chitosan is 100g:1g.

[0042] Example 5

[0043] A preparation method of modified polymeric aluminum ferric chloride, comprising the following steps:

[0044] The hyperbranched polyamide grafted chitosan prepared in Example 2 is added into isopropanol and sodium hydroxide aqueous solution, the temperature is set to 45℃, stirring is carried out for 50min, the temperature is kept unchanged, the quaternary ammonium cation unit prepared in Example 3 is added, after the addition is completed, the temperature is raised to 60℃, and stirring is continued for 10h, after the stirring is completed, hydrochloric acid is added to adjust the pH value to 7, anhydrous ethanol is added, and then the obtained solid is dried, the drying temperature is less than 80℃, and the drying is continued until the weight is constant, to obtain cationic chitosan; the mass fraction of sodium hydroxide aqueous solution is 40%; the amount ratio of hyperbranched polyamide grafted chitosan, quaternary ammonium cation unit, isopropanol and sodium hydroxide aqueous solution is 8g:8g:100mL:10g.

[0045] Cationic chitosan was added to the polyaluminum ferric chloride dispersion prepared in Example 1, and the mixture was stirred and mixed at 25°C for 65 min, followed by aging for 24 h to obtain a modified polyaluminum ferric chloride. The ratio of polyaluminum ferric chloride dispersion to modified chitosan was 100 g: 3 g.

[0046] Example 6

[0047] A method for preparing modified polyaluminum ferric chloride includes the following steps:

[0048] The hyperbranched polyamide-grafted chitosan prepared in Example 2 was added to an aqueous solution of isopropanol and sodium hydroxide. The temperature was set at 50°C and stirred for 60 min. The temperature was kept constant, and the quaternized cationic unit prepared in Example 3 was added. After the addition was complete, the temperature was raised to 60°C and stirring was continued for 10 h. After stirring, hydrochloric acid was added to adjust the pH to 7, and anhydrous ethanol was added for washing and soaking. The obtained solid was dried at a temperature below 80°C until constant weight was obtained to obtain cationic chitosan. The mass fraction of the sodium hydroxide aqueous solution was 40%. The ratio of hyperbranched polyamide-grafted chitosan, quaternized cationic unit, isopropanol and sodium hydroxide aqueous solution was 8 g: 8 g: 100 mL: 10 g.

[0049] Cationic chitosan was added to the polyaluminum ferric chloride dispersion prepared in Example 1, and the mixture was stirred and mixed at 25°C for 70 min, followed by aging for 24 h to obtain a modified polyaluminum ferric chloride. The ratio of polyaluminum ferric chloride dispersion to modified chitosan was 100 g: 4 g.

[0050] Comparative Example 2

[0051] Compared with Example 6, this comparative example uses the polyaluminum ferric chloride dispersion instead of the sample prepared in Comparative Example 1, while the other raw materials and preparation process remain the same as in Example 6.

[0052] Performance tests were conducted on Examples 4-6 and Comparative Example 2, and COD was determined using the potassium dichromate method. The initial COD content was 3.0-3.5 mg / L; the sample dosage was adjusted, and the COD removal rate was recorded after 5 minutes.

[0053] Table 1

[0054] Item Example 4 Example 5 Example 6 Comparative Example 2 10 mg / L 29.6％ 29.7％ 29.9％ 27.1％ 20 mg / L 32.4％ 32.7％ 32.6％ 28.7％ 30 mg / L 41.8％ 41.2％ 41.5％ 37.2％

[0055] As shown in Table 1, the introduction of calcium ions into the treated polyaluminum ferric chloride dispersion resulted in calcium ions having an ionic radius of approximately [missing value]. It can replace sodium ions present in the flocculation process of polyaluminum ferric chloride dispersion, making the flocculation structure more porous, better carrying out the adsorption process, shortening the adsorption time, and thus improving the adsorption stability.

[0056] Comparative Example 3

[0057] Compared with Example 6, this comparative example replaces cationic chitosan with untreated chitosan, while the other raw materials and preparation process remain the same as in Example 6.

[0058] Comparative Example 4

[0059] Compared with Comparative Example 2, the cationic chitosan in this comparative example was replaced with the hyperbranched polyamide-grafted chitosan prepared in Example 1, while the other raw materials and preparation process remained the same as those in Comparative Example 2.

[0060] The samples prepared in Examples 4-6 and Comparative Examples 3-4 were tested. Test water samples were prepared using CI Reactive Black 5 dye at a dosage of 1 g / L. The decolorization rate was calculated based on absorbance. Absorbance was measured using a 721 spectrophotometer at 80°C for 3 hours. The sample dosage was 0.5 g / L, and the decolorization rate was recorded. The results are shown in Table 2.

[0061] Table 2

[0062]

[0063]

[0064] As shown in Table 2, the modified polyaluminum ferric chloride prepared in this invention has good acid and alkali resistance due to the presence of amide bonds, which have different temperature, pressure, acid, alkali, and salt resistance from other quaternary ammonium salt polymers. Under a wide pH range, the decolorization effect is stable. The quaternary ammonium salt and amide bonds in its structure can ensure the stability of decolorization. In addition, the high positive charge of polyaluminum ferric chloride combined with the entrainment effect of cationic chitosan effectively improves the decolorization flocculation effect and increases the adsorption capacity.

[0065] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0066] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a modified polyaluminum ferrichloride, characterized by, It comprises the following steps: The hyperbranched polyamide grafted chitosan is added into isopropyl alcohol and sodium hydroxide aqueous solution, the temperature is set to 45-50℃, stirring for 50-60 min, keeping the temperature unchanged, adding quaternary ammonium cation unit, after adding, the temperature is raised to 60℃, continue stirring for 10 h, after stirring, adjust the pH value to 7, add anhydrous ethanol, washing and soaking, dry the obtained solid, to obtain cationic chitosan; Polyaluminum chloride solution, ferric chloride, deionized water and calcium chloride are mixed, stirring and reacting for 30 min at 20℃, then the temperature is raised to 70℃, continue to react for 4 h, to obtain polyaluminum ferric chloride dispersion; the cationic chitosan is added into the polyaluminum ferric chloride dispersion, stirring and mixing for 60-70 min at 20-25℃, then aging for 24 h, to obtain a modified polyaluminum ferric chloride.

2. The method for preparing modified polymeric aluminum ferric chloride according to claim 1, characterized in that, The mass fraction of the sodium hydroxide aqueous solution is 40%; the amount ratio of the hyperbranched polyamide grafted chitosan, quaternary ammonium cation unit, isopropyl alcohol and sodium hydroxide aqueous solution is 8g:8g:100mL:10g.

3. The method for preparing modified polymeric aluminum ferric chloride according to claim 1, characterized in that, The mass fraction of the polyaluminum chloride solution is 40%, the amount ratio of the polyaluminum chloride solution, ferric chloride, deionized water and calcium chloride is 100mL:35.6g:35mL:2.4g.

4. The method for preparing modified polymeric ferric aluminum chloride according to claim 1, characterized in that, The hyperbranched polyamide grafted chitosan is prepared by the following steps: The chitosan and water are mixed and stirred, after stirring and dispersing, the glutaraldehyde aqueous solution is added and stirred for 30 min, the hyperbranched polyamide aqueous solution is added, the temperature is raised to 40℃, stirring for 1 h, after reaction, vacuum drying, grinding through 100 mesh sieve to obtain the hyperbranched polyamide grafted chitosan; the mass fraction of the glutaraldehyde aqueous solution is 2%, the mass fraction of the hyperbranched polyamide aqueous solution is 50%, the amount ratio of the chitosan, water, glutaraldehyde aqueous solution and hyperbranched polyamide aqueous solution is 2g:100mL:100mL:5mL.

5. The method for preparing modified polymeric ferric aluminum chloride according to claim 1, characterized in that, The quaternary ammonium cation unit is prepared by the following steps: The N-[3-(dimethylamino)propyl]acetamide and deionized water are mixed, then hydrochloric acid is added, adjusting the pH value to 7-8, adding epichlorohydrin, stirring and reacting for 1 h at 30℃, after reaction, adding distilled water and stirring and mixing, standing and separating, extracting with water and ethyl acetate, the obtained organic matter is concentrated under reduced pressure, to obtain the quaternary ammonium cation unit; the amount ratio of the N-[3-(dimethylamino)propyl]acetamide, epichlorohydrin and deionized water is 0.02mol:0.03mol:30mL.

6. The method for preparing modified polymeric ferric aluminum chloride according to claim 1, characterized in that, The amount ratio of the polyaluminum ferric chloride dispersion and modified chitosan is 100g:1-4g. 7.A modified polyaluminum ferric chloride prepared by the preparation method of any one of claims 1-6. 8.The application of the modified polyaluminum ferric chloride prepared by the preparation method of any one of claims 1-6 in printing and dyeing wastewater.

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