Aluminum-manganese composite coagulant, preparation method and application thereof
By preparing an aluminum-manganese composite coagulant, combining the advantages of aluminum and manganese salts, stable Al-O-Mn bonds and Si-OH polymers are formed, solving the problems of low efficiency and manganese residue in aluminum-based coagulants when removing natural organic matter. This achieves efficient flocculation and sedimentation and low residue water treatment effects over a wide pH range.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ANHUI UNIVERSITY OF TECHNOLOGY
- Filing Date
- 2024-11-04
- Publication Date
- 2026-06-26
Smart Images
Figure CN119191507B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of wastewater treatment agent technology, specifically to an aluminum-manganese composite coagulant, its preparation method, and its application. Background Technology
[0002] Humic acid (HA) is a major natural organic compound (NOM) widely found in soil, water bodies, and sediments. In drinking water treatment, chlorine is commonly used as a disinfectant. Chlorine reacts with HA to form disinfection byproducts (DBPs), posing a threat to drinking water quality safety. Coagulation, as a crucial step in drinking water treatment, is widely used in water and wastewater treatment due to its low cost, simple operation, and high efficiency in removing suspended particles and organic matter. The type of coagulant is a key factor determining the coagulation effect.
[0003] Traditional aluminum-based coagulants suffer from several drawbacks (such as high dosage, large sludge production, low efficiency in removing small-molecule organic matter, and an optimal removal pH range of 5-7, while the pH of natural water bodies is typically neutral or even slightly alkaline), making them difficult to fully utilize in practical applications. Compared to single coagulants, combinations of multiple metal salts hold promise for leveraging the advantages of various metal-based coagulants and overcoming the shortcomings of single-metal-based coagulants. Chinese patent CN102897878A discloses a high-efficiency water treatment flocculant formulated by compounding potassium permanganate, aluminum salt flocculant, and auxiliary coagulant in a specific ratio. This formulation maximizes the coagulation aid capabilities of potassium permanganate and the auxiliary coagulant, thereby improving the efficiency of the composite coagulant in removing organic pollutants, algae, and turbidity, eliminating precursors of disinfection byproducts in water, improving water quality, and saving on chemicals. However, some problems still exist in this process, such as water quality safety hazards caused by aluminum and manganese residues, and the problem of excessive residual manganese. At the same time, special attention should be paid to the ratio of permanganate and aluminum salt coagulants. An imbalance in the ratio may cause excessive oxidation, resulting in reduced coagulation performance, or excessive coagulant, resulting in floc re-stabilization. Summary of the Invention
[0004] To address the problems existing in the prior art, this invention provides an aluminum-manganese composite coagulant, its preparation method, and its application. The aluminum-manganese composite coagulant provided by this invention has a wider pH adaptability range, can improve the ability to remove natural organic matter, and can also reduce color problems caused by manganese residue.
[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:
[0006] This invention provides a method for preparing an aluminum-manganese composite coagulant, comprising the following steps:
[0007] Dissolve aluminum salts and manganese salts to obtain a solution containing aluminum salts and manganese salts;
[0008] The solutions containing aluminum and manganese salts and the alkaline solution are first mixed to obtain a first mixture.
[0009] The first mixture, sodium silicate solution, and polyacrylamide solution are mixed again, and the resulting second mixture is allowed to stand and mature to obtain an aluminum-manganese composite coagulant.
[0010] Preferably, the aluminum salt is aluminum chloride and / or aluminum sulfate; the manganese salt is manganese chloride and / or manganese sulfate.
[0011] Preferably, in the solution containing aluminum and manganese salts, the molar ratio of aluminum ions to manganese ions is 2 to 9:1.
[0012] Preferably, the alkaline solution is one or more of sodium hydroxide solution, sodium bicarbonate solution, potassium hydroxide solution and potassium bicarbonate solution, and the concentration of the alkaline solution is 0.25-0.50 mol / L; the alkalinity of the first mixture is 1.0-2.0.
[0013] Preferably, the first mixing involves stirring a solution containing aluminum and manganese salts under water bath conditions while simultaneously adding an alkaline solution dropwise to the solution containing aluminum and manganese salts.
[0014] Preferably, the temperature of the water bath is 40–70°C, and the stirring speed is 350–400 rpm.
[0015] Preferably, the sodium silicate solution has a mass concentration of 10-30%; and the polyacrylamide solution has a mass concentration of 2-5%.
[0016] Preferably, the settling and ripening time is 12 to 24 hours.
[0017] The present invention also provides an aluminum-manganese composite coagulant prepared by the preparation method described in the above technical solution.
[0018] This invention also provides the application of the aluminum-manganese composite coagulant prepared by the preparation method described above, or the aluminum-manganese composite coagulant described above, in the treatment of organic matter in water under moderately alkaline conditions, wherein the organic matter is humic acid.
[0019] This invention provides a method for preparing an aluminum-manganese composite coagulant, comprising the following steps: dissolving aluminum salt and manganese salt to obtain a solution containing aluminum salt and manganese salt; firstly mixing the solution containing aluminum salt and manganese salt with an alkaline solution to obtain a first mixture; secondly mixing the first mixture with a sodium silicate solution and a polyacrylamide solution, and allowing the resulting second mixture to stand and mature to obtain the aluminum-manganese composite coagulant.
[0020] Compared with existing technologies, the preparation method provided by this invention has the following advantages:
[0021] (1) The preparation conditions of this invention can be carried out at room temperature. It is simple to operate, has low energy consumption, is safe and environmentally friendly, uses inexpensive and readily available raw materials, and produces an economical and efficient coagulant that is suitable for market promotion and application.
[0022] (2) This invention utilizes the dissolution of inorganic aluminum-manganese salts and the addition of alkali to hydrolyze and condense to form Al-O-Mn bonds, thus achieving a composite. The composite aluminum-manganese coagulant combines the advantages of aluminum salts and manganese salts. Among them, aluminum salts have strong electrical neutralization ability, and the addition of a certain amount of manganese salt makes the original single aluminum salt coagulant have a wider pH range, improves the ability to remove natural organic matter, and can also reduce the color problem caused by manganese residue.
[0023] (3) Sodium silicate is added during the preparation process of this invention. It forms a polymeric silicate containing Si-OH through reaction, which has a strong adsorption enhancement ability and strong adaptability to pH. It can also connect Al and Mn through condensation reaction to form a stable chemical bond. It is very easy to flocculate and settle during water treatment, reducing chemical residues.
[0024] (4) A certain amount of polyacrylamide was added during the preparation process of this invention. It is a high molecular polymer with a high molecular chain and functional groups. Compared with traditional inorganic coagulants, it enhances the adsorption and bridging ability of pollutants in water and improves the removal efficiency. Attached Figure Description
[0025] Figure 1 Fourier transform infrared spectra of the coagulants prepared in Examples 1-2 and Comparative Example 1 of this invention;
[0026] Figure 2 The graph shows the effect of PAC and coagulants with different aluminum-manganese ratios on the removal of humic acid at different pH values under two alkalinities.
[0027] Figure 3 The graph shows the humic acid removal rate of the aluminum-manganese polymeric coagulant prepared in Example 2 of the present invention and the simple compounded conventional coagulant in Comparative Example 3 at different dosages.
[0028] Figure 4 The graph shows the residual aluminum and manganese content of the aluminum-manganese polymeric coagulant prepared in Example 2 of this invention and the simple compounded conventional coagulant in Comparative Example 3 after treating humic acid water.
[0029] Figure 5 The images show the morphological distribution of aluminum-manganese polymeric coagulants prepared in Examples 2 and 9-10 of this invention, specifically the aluminum-manganese hydrolyzed hydroxyl complex species. Detailed Implementation
[0030] This invention provides a method for preparing an aluminum-manganese composite coagulant, comprising the following steps:
[0031] Dissolve aluminum salts and manganese salts to obtain a solution containing aluminum salts and manganese salts;
[0032] The solutions containing aluminum and manganese salts and the alkaline solution are first mixed to obtain a first mixture.
[0033] The first mixture, sodium silicate solution, and polyacrylamide solution are mixed again, and the resulting second mixture is allowed to stand and mature to obtain an aluminum-manganese composite coagulant.
[0034] This invention dissolves aluminum salts and manganese salts to obtain a solution containing aluminum salts and manganese salts.
[0035] In one embodiment, the aluminum salt is aluminum chloride and / or aluminum sulfate; in a specific example, the aluminum salt may be aluminum chloride. In another embodiment, the aluminum chloride is of analytical grade.
[0036] In one embodiment, the manganese salt is manganese chloride and / or manganese sulfate; in a specific embodiment, the manganese salt can be manganese chloride. In another embodiment, the manganese chloride is of analytical grade.
[0037] In one embodiment, the molar ratio of aluminum ions to manganese ions in the solution containing aluminum and manganese salts is 2 to 9:1. In specific embodiments, the molar ratio of aluminum ions to manganese ions can be 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, and 9:1.
[0038] As one implementation method, the dissolution is carried out by stirring, and the stirring time is ≥20 min.
[0039] After obtaining a solution containing aluminum and manganese salts, the present invention first mixes the solution containing aluminum and manganese salts with an alkaline solution to obtain a first mixed solution.
[0040] In one embodiment, the first mixing involves stirring a solution containing aluminum and manganese salts under water bath conditions while simultaneously adding an alkaline solution dropwise to the solution containing aluminum and manganese salts.
[0041] In one embodiment, the alkaline solution is one or more selected from sodium hydroxide solution, sodium bicarbonate solution, potassium hydroxide solution, and potassium bicarbonate solution. In a specific embodiment, the alkaline solution can be sodium hydroxide solution. In one embodiment, the concentration of the alkaline solution is 0.25–0.5 mol / L. In a specific embodiment, the concentration of the alkaline solution can be 0.3–0.45 mol / L.
[0042] As one implementation method, the temperature of the water bath is 40-70°C. In a specific embodiment, the temperature of the water bath can be 40°C.
[0043] In one embodiment, the stirring speed is 350 to 400 rpm.
[0044] In one implementation, the dripping rate is 14 drops / 30 seconds.
[0045] In one embodiment, the alkalinity of the first mixture is 1.0 to 2.0. In a specific embodiment, the alkalinity of the first mixture can be 1.0 or 2.0.
[0046] After obtaining the first mixture, the present invention mixes the first mixture, sodium silicate solution and polyacrylamide solution a second time, and the resulting second mixture is allowed to stand and mature to obtain an aluminum-manganese composite coagulant.
[0047] In one embodiment, the sodium silicate solution has a mass concentration of 10-30%, and in a specific embodiment, the mass concentration of the sodium silicate solution is 20%. In another embodiment, the polyacrylamide solution has a mass concentration of 2-5%, and in a specific embodiment, the mass concentration of the polyacrylamide solution can be 3%.
[0048] In one embodiment, the second mixing method is stirring, wherein the stirring speed is 350-400 rpm and the time is ≥60 min.
[0049] As one implementation method, the standing and ripening time is 12 to 24 hours. In a specific embodiment, the standing and ripening time can be 24 hours.
[0050] The present invention also provides an aluminum-manganese composite coagulant prepared by the preparation method described above.
[0051] This invention also provides the application of the aluminum-manganese composite coagulant prepared by the above-described preparation method, or the aluminum-manganese composite coagulant, in the treatment of organic matter in water under neutral or weakly alkaline conditions.
[0052] In one embodiment, the organic compound is humic acid.
[0053] In one embodiment, the amount of aluminum-manganese composite coagulant added is 20-30 mg per 1 L of water to be treated. In another embodiment, the pH value of the water to be treated is 6-8.
[0054] When using the aluminum-manganese composite coagulant provided by this invention to treat water bodies, the following advantages are available:
[0055] (1) The coagulant provided by the present invention combines aluminum and manganese salts, and the coagulant has strong stability. It only needs to be added once to ensure good coagulation effect. Compared with single coagulants, the coagulant of the present invention is more convenient to use.
[0056] (2) The coagulant provided by the present invention has a stronger ability to remove humic acid under moderately alkaline conditions, and has a stronger removal effect than a single aluminum-based salt coagulant.
[0057] The present invention does not have any special requirements for the specific method of the application; any method known to those skilled in the art can be used.
[0058] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.
[0059] Example 1
[0060] 27 mL of 1 mol / L AlCl3 solution and 3 mL of 1 mol / L MnCl2 solution were mixed in a beaker and stirred magnetically for 20 min to obtain a mixed solution.
[0061] The mixed solution was placed in a 40°C water bath for reaction, and 120 mL of 0.5 mol / L NaOH solution was added dropwise at a rate of 14 drops per half minute until the alkalinity B reached 2.0, resulting in an alkaline mixed solution (i.e., the first mixed solution).
[0062] After obtaining the alkaline mixed solution, 2 mL of 20% sodium silicate solution and 1 mL of 3% polyacrylamide solution were added to the mixture, and the mixture was stirred and mixed for 30 minutes. The mixture was then placed in a wide-mouth bottle and allowed to mature for 24 hours to obtain an aluminum-manganese composite coagulant with Al:Mn = 9:1 and alkalinity 2.
[0063] Example 2
[0064] 20 mL of 1 mol / L AlCl3 solution and 10 mL of 1 mol / L MnCl2 solution were mixed in a beaker and stirred magnetically for 20 min to obtain a mixed solution.
[0065] The mixed solution was placed in a 40°C water bath for reaction, and 120 mL of 0.5 mol / L NaOH solution was added dropwise at a rate of 14 drops per half minute until the alkalinity B reached 2.0, resulting in an alkaline mixed solution.
[0066] After obtaining the alkaline mixed solution, 2 mL of 20% sodium silicate solution and 1 mL of 3% polyacrylamide solution were added to the mixture, and the mixture was stirred and mixed for 30 minutes. The mixture was then placed in a wide-mouth bottle and allowed to mature for 24 hours to obtain an aluminum-manganese composite coagulant with Al:Mn = 2:1 and alkalinity of 2.
[0067] Example 3
[0068] 10 mL of 1 mol / L AlCl3 solution and 20 mL of 1 mol / L MnCl2 solution were mixed in a beaker and stirred magnetically for 20 min to obtain a mixed solution.
[0069] The mixed solution was placed in a 40°C water bath for reaction, and 120 mL of 0.5 mol / L NaOH solution was added dropwise at a rate of 14 drops per half minute until the alkalinity B reached 2.0, resulting in an alkaline mixed solution.
[0070] After obtaining the alkaline mixed solution, 2 mL of 20% sodium silicate solution and 1 mL of 3% polyacrylamide solution were added to the mixture, and the mixture was stirred and mixed for 30 minutes. The mixture was then placed in a wide-mouth bottle and allowed to mature for 24 hours to obtain an aluminum-manganese composite coagulant with Al:Mn = 1:2 and alkalinity 2.
[0071] Example 4
[0072] 3 mL of 1 mol / L AlCl3 solution and 27 mL of 1 mol / L MnCl2 solution were mixed in a beaker and stirred magnetically for 20 min to obtain a mixed solution.
[0073] The mixed solution was placed in a 40°C water bath for reaction, and 120 mL of 0.5 mol / L NaOH solution was added dropwise at a rate of 14 drops per half minute until the alkalinity B reached 2.0, resulting in an alkaline mixed solution.
[0074] After obtaining the alkaline mixed solution, 2 mL of 20% sodium silicate solution and 1 mL of 3% polyacrylamide solution were added to the mixture, and the mixture was stirred and mixed for 30 minutes. The mixture was then placed in a wide-mouth bottle and allowed to mature for 24 hours to obtain an aluminum-manganese composite coagulant with Al:Mn = 1:9 and alkalinity 2.
[0075] Example 5
[0076] 27 mL of 1 mol / L AlCl3 solution and 3 mL of 1 mol / L MnCl2 solution were mixed in a beaker and stirred magnetically for 20 min to obtain a mixed solution.
[0077] The mixed solution was placed in a 40°C water bath for reaction, and 120 mL of 0.25 mol / L NaOH solution was added dropwise at a rate of 14 drops per half minute until the alkalinity B reached 1.0, thus obtaining an alkaline mixed solution.
[0078] After obtaining the alkaline mixed solution, 2 mL of 20% sodium silicate solution and 1 mL of 3% polyacrylamide solution were added to the mixture, and the mixture was stirred and mixed for 30 minutes. The mixture was then placed in a wide-mouth bottle and allowed to mature for 24 hours to obtain an aluminum-manganese composite coagulant with Al:Mn = 9:1 and alkalinity 1.
[0079] Example 6
[0080] 20 mL of 1 mol / L AlCl3 solution and 10 mL of 1 mol / L MnCl2 solution were mixed in a beaker and stirred magnetically for 20 min to obtain a mixed solution.
[0081] The mixed solution was placed in a 40°C water bath for reaction, and 120 mL of 0.25 mol / L NaOH solution was added dropwise at a rate of 14 drops per half minute until the alkalinity B reached 1.0, thus obtaining an alkaline mixed solution.
[0082] After obtaining the alkaline mixed solution, 2 mL of 20% sodium silicate solution and 1 mL of 3% polyacrylamide solution were added to the mixture, and the mixture was stirred and mixed for 30 minutes. The mixture was then placed in a wide-mouth bottle and allowed to mature for 24 hours to obtain an aluminum-manganese composite coagulant with Al:Mn = 2:1 and alkalinity of 1.
[0083] Example 7
[0084] 10 mL of 1 mol / L AlCl3 solution and 20 mL of 1 mol / L MnCl2 solution were mixed in a beaker and stirred magnetically for 20 min to obtain a mixed solution.
[0085] The mixed solution was placed in a 40°C water bath for reaction, and 120 mL of 0.25 mol / L NaOH solution was added dropwise at a rate of 14 drops per half minute until the alkalinity B reached 1.0, thus obtaining an alkaline mixed solution.
[0086] After obtaining the alkaline mixed solution, 2 mL of 20% sodium silicate solution and 1 mL of 3% polyacrylamide solution were added to the mixture, and the mixture was stirred and mixed for 30 minutes. The mixture was then placed in a wide-mouth bottle and allowed to mature for 24 hours to obtain an aluminum-manganese composite coagulant with Al:Mn = 1:2 and alkalinity of 1.
[0087] Example 8
[0088] 3 mL of 1 mol / L AlCl3 solution and 27 mL of 1 mol / L MnCl2 solution were mixed in a beaker and stirred magnetically for 20 min to obtain a mixed solution.
[0089] The mixed solution was placed in a 40°C water bath for reaction, and 120 mL of 0.25 mol / L NaOH solution was added dropwise at a rate of 14 drops per half minute until the alkalinity B reached 1.0, thus obtaining an alkaline mixed solution.
[0090] After obtaining the alkaline mixed solution, 2 mL of 20% sodium silicate solution and 1 mL of 3% polyacrylamide solution were added to the mixture, and the mixture was stirred and mixed for 30 minutes. The mixture was then placed in a wide-mouth bottle and allowed to mature for 24 hours to obtain an aluminum-manganese composite coagulant with Al:Mn = 1:9 and alkalinity of 1.
[0091] Example 9
[0092] The only difference from Example 2 is that the alkalinity is 1.0.
[0093] Example 10
[0094] The only difference from Example 2 is that the alkalinity is 2.5.
[0095] Comparative Example 1
[0096] Pour 30 mL of 1 mol / L AlCl3 solution into a beaker and stir magnetically for 20 min. Place the stirred solution in a 40℃ water bath for reaction, and add 120 mL of 0.5 mol / L NaOH solution dropwise at a rate of 14 drops per half minute until the alkalinity B is 2.0 to obtain an alkaline solution.
[0097] After obtaining the alkaline solution, 2 mL of 20% sodium silicate solution and 1 mL of 3% polyacrylamide solution were added to the mixture. The mixture was stirred and mixed for 30 minutes, and then placed in a wide-mouth bottle to mature for 24 hours to obtain polyaluminum chloride (PAC) with an alkalinity of 2.
[0098] Comparative Example 2
[0099] 30 mL of 1 mol / L AlCl3 solution was poured into a beaker and magnetically stirred for 20 min. The stirred solution was then placed in a 40 °C water bath for reaction, and 120 mL of 0.25 mol / L NaOH solution was added dropwise at a rate of 14 drops per half minute until the alkalinity B reached 1.0, resulting in an alkaline solution. After obtaining the alkaline solution, 2 mL of 20% sodium silicate solution and 1 mL of 3% polyacrylamide solution were added to the mixture, and the mixture was stirred for another 30 min. The mixture was then placed in a wide-mouth bottle and allowed to mature for 24 h to obtain PAC with an alkalinity of 1.
[0100] Comparative Example 3
[0101] 20 mL of 1 mol / L AlCl3 solution and 10 mL of 1 mol / L MnCl2 solution were successively mixed in a beaker, and then 120 mL of ultrapure water was added to dilute it so that the aluminum and manganese concentrations were consistent with those of the composite coagulant with an Al:Mn ratio of 2:1, thus obtaining a simple compound mixture.
[0102] Figure 1 The Fourier transform infrared spectra of the coagulants prepared in Examples 1-2 and Comparative Example 1 are shown below. Figure 1 It can be known that: Figure 1 The main body is 3417cm -1 1642cm -1 615cm -1 1100cm -1 The peaks, corresponding to Al-OH groups, HOH groups, and Al-OH-Al groups, confirm the presence of polymeric states in the coagulant.
[0103] Performance characterization:
[0104] Take 20 mL of 1 g / L humic acid mother liquor into a 2000 mL volumetric flask and dilute to 2000 mL to obtain a 10 mg / L humic acid solution. Adjust the pH to 6, 7, and 8. Take 250 mL of each solution into six mixing cups and conduct coagulation experiments using a ZR4-6 six-unit mixer. The coagulation procedure includes: rapid stirring, followed by slow stirring, and then sedimentation. The rapid stirring speed is 200 rpm for 2 min, the slow stirring speed is 40 rpm for 30 min, and the sedimentation time is 30 min. After coagulation, take the supernatant and measure the UV254 value using a UV spectrophotometer.
[0105] Different amounts of the coagulants obtained from the examples and comparative examples were added to humic acid solutions for coagulation water treatment. The treatment results are shown in the figure. Figure 2 , Figure 2 The graphs show the UV254 removal effects of PAC with an alkalinity of 2 at pH 6, 7, and 8, and aluminum-manganese ratios of 9:1, 2:1, 1:2, and 1:9, respectively, at different dosages. Figure 2 Figures d through f show the UV254 removal efficiency of PAC with aluminum-manganese ratios of 9:1, 2:1, 1:2, and 1:9 at different dosages for pH values of 6, 7, and 8 (alkalinity 1). Figure 2(a-c) It can be seen that at pH=6, the removal rate of PAC and Al:Mn=9:1 coagulant from Comparative Example 1 and Example 1 quickly reached 100% with increasing dosage; at pH=8, the removal rate of PAC from Comparative Example 1 at a dosage of 20 mg / L was 46.79%, while the removal rate of Al:Mn=2:1 coagulant from Example 2 at a dosage of 20 mg / L was 79.21%, indicating that the coagulant containing manganese was about 30% more effective than the one without manganese. Furthermore, under all three pH conditions, the humic acid removal efficiency of the coagulants Al:Mn=1:2 from Example 3 and Al:Mn=1:9 from Example 4 was worse than that of PAC, Al:Mn=2:1 from Example 2, and Al:Mn=9:1 from Example 1, indicating that the proportion of manganese affects the coagulation effect and should be maintained at a certain ratio to achieve better coagulation efficiency. In addition, in Figure 2 From the treatment efficiency of the coagulants in Comparative Examples 2, 5, 6, 7, and 8 in (d~f), it can be seen that the coagulants at each pH level have a lower humic acid removal rate than those in Comparative Examples 1, 1, 2, 3, and 4, indicating that the lower the alkalinity, the worse the effect of coagulation in removing humic acid.
[0106] Figure 3 This is an analytical graph showing the removal rate of humic acid by the aluminum-manganese polymeric coagulant prepared in Example 2 and the simple compounded conventional coagulant in Comparative Example 3 at different dosages. Figure 3 It can be seen that, under the same coagulant dosage, the aluminum-manganese polymeric coagulant prepared in Example 2 significantly improved the removal performance of humic acid compared to the simple compounded conventional coagulant in Comparative Example 3, with a removal rate increase of 20-41%. This indicates that the aluminum-manganese composite coagulant has a higher pollutant removal effect than the traditional simple compounded coagulant, with a richer variety of dominant aluminum species, which is more conducive to charge neutralization and adsorption of pollutants. More importantly, due to Figure 4 ( Figure 4 The graph shows the aluminum and manganese residues in the effluent after treating humic acid water with the aluminum-manganese polymeric coagulant prepared in Example 2 of this invention and the simple compounded conventional coagulant in Comparative Example 3. As can be seen, the aluminum and manganese residues in the effluent after removing humic acid with the aluminum-manganese polymeric coagulant prepared in Example 2 are significantly lower than those after removing humic acid with the simple compounded conventional coagulant in Comparative Example 3. The aluminum residue is reduced by 83% and the manganese residue is reduced by 65%, and both are lower than the requirements in the relevant drinking water quality standards. This indicates that the aluminum-manganese composite coagulant is safer and can ensure healthy water supply.
[0107] Figure 5 This is a morphological distribution diagram of the aluminum-manganese polymeric coagulant prepared in Examples 2 and 9-10 of this invention, showing the morphological distribution of the aluminum-manganese hydrolyzed hydroxyl complexes. Figure 5 It can be seen that as the amount of NaOH added increases, the alkalinity increases from 1.0 to 2.5, and the dominant species in the aluminum-manganese coagulation is the aggregated state (Al+Mn).b The content increased by 35%.
[0108] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.
Claims
1. A method for preparing an aluminum-manganese composite coagulant, comprising the following steps: Dissolve aluminum salts and manganese salts to obtain a solution containing aluminum salts and manganese salts; The solutions containing aluminum and manganese salts and the alkaline solution are first mixed to obtain a first mixture. The first mixture, sodium silicate solution and polyacrylamide solution are mixed again, and the resulting second mixture is allowed to stand and mature to obtain an aluminum-manganese composite coagulant. The aluminum salt is aluminum chloride and / or aluminum sulfate; the manganese salt is manganese chloride and / or manganese sulfate; In the solution containing aluminum and manganese salts, the molar ratio of aluminum ions to manganese ions is 2~9:1; the alkalinity of the first mixture is 1.0~2.0; The aluminum-manganese composite coagulant is used to treat organic matter in water bodies; the organic matter is humic acid.
2. The preparation method according to claim 1, characterized in that, The alkaline solution is one or more of sodium hydroxide solution, sodium bicarbonate solution, potassium hydroxide solution, and potassium bicarbonate solution, and the concentration of the alkaline solution is 0.25~0.50 mol / L.
3. The preparation method according to claim 1, characterized in that, The first mixing involves stirring a solution containing aluminum and manganese salts in a water bath while simultaneously adding an alkaline solution dropwise to the solution containing aluminum and manganese salts.
4. The preparation method according to claim 3, characterized in that, The temperature of the water bath is 40~70℃, and the stirring speed is 350~400 rpm.
5. The preparation method according to claim 1, characterized in that, The sodium silicate solution has a mass concentration of 10-30%; the polyacrylamide solution has a mass concentration of 2-5%.
6. The preparation method according to claim 5, characterized in that, The settling and ripening time is 12-24 hours.
7. The aluminum-manganese composite coagulant prepared by the preparation method according to any one of claims 1 to 6.
8. The application of the aluminum-manganese composite coagulant prepared by the preparation method according to any one of claims 1 to 6 in the treatment of organic matter in water under moderately alkaline conditions, characterized in that, The organic matter is humic acid.