A polyaluminum chloride water purifier and its preparation method

Abstract

This invention relates to the field of water purification technology, specifically to a polyaluminum chloride water purifier and its preparation method. The polyaluminum chloride water purifier of this invention achieves molecular-level hybridization and functional synergy through in-situ composite of polyamined ferric oxide and aluminum chloride, thereby significantly improving water purification performance. Specific steps include: (1) ammoniation modification of ferric oxide; (2) polyamine treatment of the ammonified ferric oxide; (3) hydrolysis and polymerization of the polyamined ferric oxide and aluminum chloride, followed by aging. It exhibits strong adsorption capacity for COD, heavy metals, and suspended solids, and the product also possesses magnetic separation capabilities, making it suitable for treating highly challenging industrial wastewater.

Description

Technical Field

[0001] This invention relates to the field of water purification technology, specifically to a polyaluminum chloride water purifier and its preparation method. Background Technology

[0002] Flocculants are water treatment agents that aggregate colloidal substances and particulate matter suspended in a liquid, forming larger flocculent structures. These flocs then settle from a stable suspension, increasing the settling speed of impurities in the water and improving its clarity. Based on their chemical properties, flocculants can be classified into five main categories: inorganic, organic, biological, composite, and compound. Polyaluminum chloride (PAC), as a commonly used inorganic polymeric flocculant, is widely used in the treatment of drinking water, municipal wastewater, and industrial wastewater from chemical, metallurgical, and petroleum industries due to its excellent flocculation performance, fast settling speed, strong adaptability, low dosage, and low water treatment cost.

[0003] Patent document CN114195176B discloses a preparation process for polyaluminum chloride water purifier. The polyaluminum chloride prepared by this invention has advantages such as low impurity content and high purity. Patent document CN112850765B discloses a quality control method for producing polyaluminum ferric chloride from aluminum ash. This invention not only eliminates the environmental pollution caused by aluminum ash itself, but also avoids secondary pollution to water bodies caused by the produced polyaluminum ferric chloride during use. However, the water purification and flocculation effects of both still need to be improved. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a polyaluminum chloride water purifier and its preparation method, so as to provide a polyaluminum chloride water treatment agent with excellent water purification function.

[0005] To achieve the above objectives, the present invention provides a method for preparing polyaluminum chloride water purifier, comprising the following steps:

[0006] S1: Add ferric oxide to an ethanol aqueous solution, sonicate for 20 min, then add ammonia, stir for 10 min, then add tetraethyl orthosilicate and 3-aminopropyltriethoxysilane, stir for 6 h, centrifuge, wash, and dry to obtain aminated ferric oxide.

[0007] S2: Add aminated iron oxide to methanol, sonicate for 30 min, then add methyl acrylate, stir and react at room temperature for 24 h, then add tetraethylenepentamine and diamine-terminated polyethylene glycol, heat to 50-55℃, stir and react for 12 h to obtain polyamined iron oxide.

[0008] S3: Add polyamined iron oxide to deionized water, ultrasonically disperse for 30 min, then add aluminum chloride, stir for 30 min, adjust the pH to 3-4 with hydrochloric acid, raise the temperature to 60-65℃, hydrolyze for 1-2 h, raise the temperature to 80-85℃, polymerize for 1-2 h, cool to room temperature, age for 24 h, centrifuge, and dry to obtain polyaluminum chloride water purifier;

[0009] The ratio of the amounts of iron(III) oxide, aqueous ethanol solution, ammonia, tetraethyl orthosilicate, and 3-aminopropyltriethoxysilane in step S1 is 5-6g:500-600g:10-12g:12-14g:2-3g.

[0010] In step S2, the ratio of aminated iron oxide, methanol, methyl acrylate, tetraethylenepentamine, and diamine-terminated polyethylene glycol is 5-6g:500-550g:0.5-0-6g:1.5-1.8g:1-1.5g.

[0011] In step S3, the ratio of polyamined iron oxide, deionized water, and aluminum chloride is 4-5g: 500-600g: 20-25g.

[0012] Preferably, the average particle size of the iron oxide in step S1 is 300-400 nm.

[0013] Preferably, the concentration of the ethanol aqueous solution in step S1 is 80wt%-85wt%.

[0014] Preferably, the concentration of the ammonia water in step S1 is 28wt%-30wt%.

[0015] Preferably, the weight-average molecular weight of the diamino-terminated polyethylene glycol in step S2 is 1000.

[0016] Preferably, the pH adjustment in step S3 is performed using hydrochloric acid.

[0017] Furthermore, the present invention also provides a polyaluminum chloride water purifier.

[0018] The beneficial effects of this invention are:

[0019] The polyaluminum chloride water purifier of the present invention has excellent water purification capabilities, high COD removal rate in sewage, and can significantly improve the light transmittance of sewage, resulting in good water purification effect.

[0020] The polyaluminum chloride water purifier of the present invention incorporates ferric oxide into the polymerization process of aluminum chloride, enabling ferric oxide to form a molecular-level complex with polyaluminum chloride and simultaneously forming multinucleated active sites, thereby enhancing its electrostatic and chemical bridging effects.

[0021] The polyaluminum chloride water purifier of the present invention, by using tetraethylenepentamine and diamine-terminated polyethylene glycol to polyamine iron oxide, can form a denser and more extensive dendritic cross-linked network, thereby enhancing the adsorption of free impurities and particles in water and enhancing the "bridging" and "netting" effects. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0023] Example 1: A polyaluminum chloride water purifier, the specific preparation steps are as follows:

[0024] (1) Add 5g of iron(III) oxide (average particle size 300nm) to 500g of ethanol aqueous solution (concentration 80wt%), disperse ultrasonically for 20min, then add 10g of ammonia (28wt%), stir for 10min, then add 12g of tetraethyl orthosilicate and 2g of 3-aminopropyltriethoxysilane, stir for 6h, centrifuge, wash, and dry to obtain aminated iron(III) oxide;

[0025] (2) Add 5g of aminated iron oxide to 500g of methanol, disperse ultrasonically for 30min, then add 0.5g of methyl acrylate, stir and react at room temperature for 24h, then add 1.5g of tetraethylenepentamine and 1g of bi-amino polyethylene glycol (weight average molecular weight 1000), heat to 50℃, stir and react for 12h to obtain polyamined iron oxide;

[0026] (3) Add 4g of polyamined iron oxide to 500g of deionized water, ultrasonically disperse for 30min, then add 20g of aluminum chloride, stir for 30min, adjust the pH to 3.1 with hydrochloric acid, raise the temperature to 60℃, hydrolyze for 1h, raise the temperature to 80℃, polymerize for 1h, cool to room temperature, age for 24h, centrifuge, and dry to obtain polyaluminum chloride water purifier.

[0027] Example 2: A polyaluminum chloride water purifier, the specific preparation steps are as follows:

[0028] (1) Add 5.5g of iron(III) oxide (average particle size 300nm) to 550g of ethanol aqueous solution (concentration 83wt%), disperse ultrasonically for 20min, then add 11g of ammonia (28wt%), stir for 10min, then add 13g of tetraethyl orthosilicate and 2.5g of 3-aminopropyltriethoxysilane, stir for 6h, centrifuge, wash, and dry to obtain aminated iron(III) oxide;

[0029] (2) Add 5.5g of aminated iron oxide to 520g of methanol, disperse ultrasonically for 30min, then add 0.55g of methyl acrylate, stir and react at room temperature for 24h, then add 1.7g of tetraethylenepentamine and 1.3g of diamine-terminated polyethylene glycol (weight average molecular weight 1000), heat to 50℃, stir and react for 12h to obtain polyamined iron oxide;

[0030] (3) Add 4.5g of polyamined iron oxide to 550g of deionized water, disperse ultrasonically for 30min, then add 23g of aluminum chloride, stir for 30min, adjust the pH to 3.4 with hydrochloric acid, raise the temperature to 63℃, hydrolyze for 2h, raise the temperature to 83℃, polymerize for 2h, cool to room temperature, age for 24h, centrifuge, and dry to obtain polyaluminum chloride water purifier.

[0031] Example 3: A polyaluminum chloride water purifier, the specific preparation steps are as follows:

[0032] (1) Add 5.8g of iron(III) oxide (average particle size 400nm) to 500g of ethanol aqueous solution (concentration 85wt%), disperse ultrasonically for 20min, then add 12g of ammonia (30wt%), stir for 10min, then add 13g of tetraethyl orthosilicate and 2.7g of 3-aminopropyltriethoxysilane, stir for 6h, centrifuge, wash, and dry to obtain aminated iron(III) oxide;

[0033] (2) Add 5.5g of aminated iron oxide to 550g of methanol, disperse ultrasonically for 30min, then add 0.6g of methyl acrylate, stir and react at room temperature for 24h, then add 1.6g of tetraethylenepentamine and 1.4g of diamine-terminated polyethylene glycol (weight average molecular weight 1000), heat to 50℃, stir and react for 12h to obtain polyamined iron oxide;

[0034] (3) Add 5g of polyamined iron oxide to 500g of deionized water, disperse ultrasonically for 30min, then add 24g of aluminum chloride, stir for 30min, adjust the pH to 3.8 with hydrochloric acid, raise the temperature to 65℃, hydrolyze for 1h, raise the temperature to 85℃, polymerize for 1h, cool to room temperature, age for 24h, centrifuge, and dry to obtain polyaluminum chloride water purifier.

[0035] Example 4: A polyaluminum chloride water purifier, the specific preparation steps are as follows:

[0036] (1) Add 6g of iron(III) oxide (average particle size 400nm) to 600g of ethanol aqueous solution (concentration 85wt%), disperse ultrasonically for 20min, then add 12g of ammonia (30wt%), stir for 10min, then add 14g of tetraethyl orthosilicate and 3g of 3-aminopropyltriethoxysilane, stir for 6h, centrifuge, wash, and dry to obtain aminated iron(III) oxide;

[0037] (2) Add 6g of aminated iron oxide to 550g of methanol, disperse ultrasonically for 30min, then add 0.6g of methyl acrylate, stir and react at room temperature for 24h, then add 1.8g of tetraethylenepentamine and 1.5g of diamine-terminated polyethylene glycol (weight average molecular weight 1000), heat to 50℃, stir and react for 12h to obtain polyamined iron oxide;

[0038] (3) Add 5g of polyamined iron oxide to 600g of deionized water, ultrasonically disperse for 30min, then add 25g of aluminum chloride, stir for 30min, adjust the pH to 4 with hydrochloric acid, raise the temperature to 65℃, hydrolyze for 2h, raise the temperature to 85℃, polymerize for 2h, cool to room temperature, age for 24h, centrifuge, and dry to obtain polyaluminum chloride water purifier.

[0039] Comparative Example 1: The difference from Example 2 is that tetraethylenepentamine is not added in step (2). The specific preparation steps are as follows:

[0040] (1) Add 5.5g of iron(III) oxide (average particle size 300nm) to 550g of ethanol aqueous solution (concentration 83wt%), disperse ultrasonically for 20min, then add 11g of ammonia (28wt%), stir for 10min, then add 13g of tetraethyl orthosilicate and 2.5g of 3-aminopropyltriethoxysilane, stir for 6h, centrifuge, wash, and dry to obtain aminated iron(III) oxide;

[0041] (2) Add 5.5g of aminated iron oxide to 520g of methanol, disperse ultrasonically for 30min, then add 0.55g of methyl acrylate, stir and react at room temperature for 24h, then add 1.3g of diamine-terminated polyethylene glycol (weight average molecular weight 1000), heat to 50℃, stir and react for 12h to obtain polyamine-terminated iron oxide;

[0042] (3) Add 4.5g of polyamined iron oxide to 550g of deionized water, disperse ultrasonically for 30min, then add 23g of aluminum chloride, stir for 30min, adjust the pH to 3.4 with hydrochloric acid, raise the temperature to 63℃, hydrolyze for 2h, raise the temperature to 83℃, polymerize for 2h, cool to room temperature, age for 24h, centrifuge, and dry to obtain polyaluminum chloride water purifier.

[0043] Comparative Example 2: The difference from Example 2 is that bi-amino-terminated polyethylene glycol is not added in step (2). The specific preparation steps are as follows:

[0044] (1) Add 5.5g of iron(III) oxide (average particle size 300nm) to 550g of ethanol aqueous solution (concentration 83wt%), disperse ultrasonically for 20min, then add 11g of ammonia (28wt%), stir for 10min, then add 13g of tetraethyl orthosilicate and 2.5g of 3-aminopropyltriethoxysilane, stir for 6h, centrifuge, wash, and dry to obtain aminated iron(III) oxide;

[0045] (2) Add 5.5g of aminated iron oxide to 520g of methanol, disperse ultrasonically for 30min, then add 0.55g of methyl acrylate, stir and react at room temperature for 24h, then add 1.7g of tetraethylenepentamine, heat to 50℃, stir and react for 12h to obtain polyamined iron oxide;

[0046] (3) Add 4.5g of polyamined iron oxide to 550g of deionized water, disperse ultrasonically for 30min, then add 23g of aluminum chloride, stir for 30min, adjust the pH to 3.4 with hydrochloric acid, raise the temperature to 63℃, hydrolyze for 2h, raise the temperature to 83℃, polymerize for 2h, cool to room temperature, age for 24h, centrifuge, and dry to obtain polyaluminum chloride water purifier.

[0047] Comparative Example 3: The difference from Example 2 is that only ethylenediamine is added in step (2). The specific preparation steps are as follows:

[0048] (1) Add 5.5g of iron(III) oxide (average particle size 300nm) to 550g of ethanol aqueous solution (concentration 83wt%), disperse ultrasonically for 20min, then add 11g of ammonia (28wt%), stir for 10min, then add 13g of tetraethyl orthosilicate and 2.5g of 3-aminopropyltriethoxysilane, stir for 6h, centrifuge, wash, and dry to obtain aminated iron(III) oxide;

[0049] (2) Add 5.5g of aminated iron oxide to 520g of methanol, disperse ultrasonically for 30min, then add 0.55g of methyl acrylate, stir and react at room temperature for 24h, then add 3g of ethylenediamine, heat to 50℃, stir and react for 12h to obtain polyamined iron oxide;

[0050] (3) Add 4.5g of polyamined iron oxide to 550g of deionized water, disperse ultrasonically for 30min, then add 23g of aluminum chloride, stir for 30min, adjust the pH to 3.4 with hydrochloric acid, raise the temperature to 63℃, hydrolyze for 2h, raise the temperature to 83℃, polymerize for 2h, cool to room temperature, age for 24h, centrifuge, and dry to obtain polyaluminum chloride water purifier.

[0051] Comparative Example 4: The difference from Example 2 is that aluminum chloride is polymerized first, and then polyamined iron oxide is added after the polymerization is complete. The specific preparation steps are as follows:

[0052] (1) Add 5.5g of iron(III) oxide (average particle size 300nm) to 550g of ethanol aqueous solution (concentration 83wt%), disperse ultrasonically for 20min, then add 11g of ammonia (28wt%), stir for 10min, then add 13g of tetraethyl orthosilicate and 2.5g of 3-aminopropyltriethoxysilane, stir for 6h, centrifuge, wash, and dry to obtain aminated iron(III) oxide;

[0053] (2) Add 5.5g of aminated iron oxide to 520g of methanol, disperse ultrasonically for 30min, then add 0.55g of methyl acrylate, stir and react at room temperature for 24h, then add 1.7g of tetraethylenepentamine and 1.3g of diamine-terminated polyethylene glycol (weight average molecular weight 1000), heat to 50℃, stir and react for 12h to obtain polyamined iron oxide;

[0054] (3) Add 23g of aluminum chloride to 550g of deionized water, ultrasonically disperse for 30min, adjust the pH to 3.4 with hydrochloric acid, raise the temperature to 63℃, hydrolyze for 2h, raise the temperature to 83℃, polymerize for 2h, cool to room temperature, add 4.5g of polyamined iron oxide, stir for 30min, age for 24h, centrifuge, and dry to obtain polyaluminum chloride water purifier.

[0055] Comparative Example 5: The difference from Example 2 is that aluminum chloride is polymerized first, and then iron oxide is added after the polymerization is complete. The specific preparation steps are as follows:

[0056] Add 23g of aluminum chloride to 550g of deionized water, sonicate for 30min, adjust the pH to 3.4 with hydrochloric acid, raise the temperature to 63℃, hydrolyze for 2h, raise the temperature to 83℃, polymerize for 2h, cool to room temperature, add 4.5g of iron(III) oxide, stir for 30min, age for 24h, centrifuge, and dry to obtain polyaluminum chloride water purifier.

[0057] Performance testing

[0058] 1100g of Yellow River water was taken, stirred at high speed, and then quickly and evenly divided into 11 beakers. The beakers were numbered as Examples 1-4, Comparative Examples 1-5, and Control Groups 1-2. Polyaluminum chloride water purification agents prepared in the Examples and Comparative Examples were added to the beaker samples according to their numbers. Commercially available polyaluminum chloride water purification agents were added to Control Group 1, and deionized water of equal weight to the water purification agents was added to Control Group 2. The water treatment mass added to the Examples, Comparative Examples, and Control Group 1 was the same. After addition, the mixture was stirred at 50r / min for 10min. Then, the supernatant was taken 3cm below the liquid surface using a pipette, and the COD, turbidity, and transmittance were measured and compared with the data before treatment. The test results are shown in Table 1.

[0059] Table 1 Performance Test Results

[0060]

[0061]

[0062] Data analysis, as shown in Table 1 (examples and control group), reveals that the water purifier of the present invention exhibits superior purification effects on Yellow River water, demonstrating better purification performance compared to commercially available polyaluminum chloride water purifiers.

[0063] As can be seen from Table 1, Example 2 and Comparative Examples 4 and 5, this invention incorporates ferric oxide into the polymerization process of aluminum chloride, enabling ferric oxide to form a molecular-level composite with polyaluminum chloride. This composite exhibits high bonding strength, is not easily dissociated, and forms multinucleated active sites, enhancing its adsorption capacity. Furthermore, the in-situ composite allows ferric oxide to be uniformly dispersed within the PAC framework structure. The polyamined ferric oxide plays a certain chemical bridging role, further enhancing the bonding strength between ferric oxide and aluminum hydrolysis products, forming a more stable hybrid structure. This allows for a more stable "bridging" effect during sedimentation and flocculation, thereby trapping surrounding particles during precipitate formation and promoting their sedimentation.

[0064] As can be seen from Table 1, Example 2 and Comparative Examples 1, 2 and 3, the present invention uses tetraethylenepentamine and diamine-terminated polyethylene glycol to polyamine iron oxide. On the one hand, the presence of more amino groups can further enhance the electrostatic effect, thereby further enhancing its flocculation effect. On the other hand, it provides more active coordination sites, which can form a tighter and more extensive dendritic cross-linked network with the Al-OH of PAC, thereby enhancing the adsorption of free impurities and particles in water and enhancing the "bridging" and "netting" effect of the flocculant. At the same time, the ether chain of diamine-terminated polyethylene glycol promotes the polymerization of polyaluminum chloride on the surface of iron oxide, and the long-chain ether bonds can be extended during the flocculation process, promoting flocculation efficiency.

[0065] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A method for preparing a polyaluminum chloride water purifying agent, characterized by, The method comprises the following steps: S1: mixing ferric oxide, ethanol aqueous solution, ammonia water, stirring, then adding tetraethyl orthosilicate and 3-aminopropyl triethoxysilane, stirring for 6 hours, purifying the product to obtain aminated ferric oxide; S2: mixing the aminated ferric oxide and methanol, adding methyl acrylate, stirring for 24 hours, then adding tetraethylenepentamine and double-end amino polyethylene glycol, heating to 50-55℃, stirring for 12 hours to obtain polyamine ferric oxide; S3: mixing the polyamine ferric oxide, deionized water and aluminum chloride, stirring, adjusting the pH to 3-4, heating to 60-65℃, hydrolyzing for 1-2 hours, then heating to 80-85℃, polymerizing for 1-2 hours, cooling to room temperature, aging for 24 hours, centrifuging, drying to obtain a polyaluminum chloride water purifier; The amount ratio of the ferric oxide, ethanol aqueous solution, ammonia water, tetraethyl orthosilicate, 3-aminopropyl triethoxysilane in step S1 is 5-6g:500-600g:10-12g:12-14g:2-3g; The amount ratio of the aminated ferric oxide, methanol, methyl acrylate, tetraethylenepentamine, double-end amino polyethylene glycol in step S2 is 5-6g:500-550g:0.5-0-6g:1.5-1.8g:1-1.5g; The amount ratio of the polyamine ferric oxide, deionized water and aluminum chloride in step S3 is 4-5g:500-600g:20-25g.

2. The preparation method of the polyaluminum chloride water purifier according to claim 1, characterized in that, The average particle size of the ferric oxide in step S1 is 300-400nm.

3. The preparation method of the polyaluminum chloride water purifier according to claim 1, characterized in that, The concentration of the ethanol aqueous solution in step S1 is 80wt%-85wt%.

4. The preparation method of the polyaluminum chloride water purifier according to claim 1, characterized in that, The concentration of the ammonia water in step S1 is 28wt%-30wt%.

5. The method for preparing the polyaluminum chloride water purifier according to claim 1, characterized in that, The weight average molecular weight of the double-end amino polyethylene glycol in step S2 is 1000.

6. The method for preparing the polyaluminum chloride water purifier according to claim 1, characterized in that, The pH is adjusted by hydrochloric acid in step S3.

7. A polyaluminum chloride water purifying agent, characterized by, The polyaluminum chloride water purifier is prepared by the method of any one of claims 1-6.

Images