CN1629359A - Process for preparing polymeric aluminium chloride through dimensionally stable anodes - Google Patents
Process for preparing polymeric aluminium chloride through dimensionally stable anodes Download PDFInfo
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- CN1629359A CN1629359A CN 200310121380 CN200310121380A CN1629359A CN 1629359 A CN1629359 A CN 1629359A CN 200310121380 CN200310121380 CN 200310121380 CN 200310121380 A CN200310121380 A CN 200310121380A CN 1629359 A CN1629359 A CN 1629359A
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Abstract
The invention discloses a process for preparing high grade polymeric aluminium chloride through electrolysis of shape stable anode, wherein aluminium chloride is used as electrolyte, shape stable anode is used as the anode, titanium as cathode, appling DC electricity for a predetermined period of time, and circulating the electrolyte.
Description
Technical Field
The invention provides a preparation method of a flocculating agent for water treatment, in particular to a flocculating agent with high total aluminum concentration and Al13A method for preparing polyaluminium chloride with high content and effective chlorine content.
Technical Field
Flocculation is an important step in water treatment processes. With the development of industry and the increasing severity of environmental and water pollution, strengthening the advanced treatment of conventional water purification technology and realizing efficient flocculation become important research and application subjects in modern water treatment technology.
The inorganic polymeric flocculant is a special chemical agent with large use amount and wide application range in the technical field of water treatment at present. Compared with traditional flocculating agents, such as aluminum sulfate, aluminum chloride, ferric chloride and the like, the flocculant can obviously improve the water purification efficiency and has the advantages of low consumption, good sedimentation performance, wide application range and the like. Among them, polyaluminium Chloride (PAC) is the most mature technology of current industrial production, has the highest efficiency, and is the most widely used inorganic polymeric flocculant.
PAC is actually a kinetic intermediate of the hydrolysis-polymerization-precipitation process of aluminum ions under artificially controlled conditions. Scientific research and application practice show that polytridecyl aluminum (chemical formula is Al)13O4(OH)24 7+，Al13) Is the best coagulation flocculation shape, and the content of the coagulation flocculation shape can reflect the flocculation efficiency of the product, so the high content of Al13Polymeric morphology is often the primary target of PAC flocculant production. The literature indicates that Al13The single molecular particle size of the form is only 2.5nm, and the nano-scale Al13The form is more and more emphasized by people. At present, the preparation method is adopted to obtain high-purity nano Al13The polymer has become a hot spot of nano PAC development at home and abroad at present, and Al13The polymer is also the leading edge of research and development in many other fields at home and abroad at present, such as catalysis, cosmetics, geochemistry, soil chemistry, material science and the like. However, it is satisfactory that the industrial production has only a high Al content13The content is not sufficient and it should be feasible at the same time to have a higher total aluminum concentration.
The development and production application of polyaluminium chloride flocculant are started in Japan in the late 60 s, and researchers in China, Japan, Europe, the former Soviet Union, the United states and the like have carried out a great deal of research work on the synthesis method and process. The development and production of PAC in the seventies of China have developed various raw materials and technological manufacturing methods, and basically unique technological routes and production systems are established by combining the conditions of China, which are unified and continue to the present.
At present, PAC is mainly produced by chemical processes. Except that a few manufacturers adopt a production process of acid dissolution of metal aluminum scraps or aluminum hydroxide gel and spray drying to produce and prepare refined PAC flocculant, most of the refined PAC flocculant is prepared by acid dissolution of bauxite and calcium aluminate powder and adjustment of the calcium aluminate powder and a roller drying method. Because the calcium aluminate powder is cheap, the calcium aluminate powder is rawThe production cost is low, but the product quality is not high, and partial crude products contain heavy metal impurities harmful to human bodies, so that the safety of drinking water is difficult to guarantee. With the emphasis and development of PAC application basic theory research, manufacturers who transition to modern production scale and international product quality begin to appear, and the manufacturers use aluminum hydroxide and hydrochloric acid as raw materials and control the materials to be suitable for the productionModerate temperatures and pressures and spray drying techniques produce better quality PACs. PACs produced by chemical processes have higher total aluminum concentrations, but Al13The content is less than 30%.
In recent years, electrochemical methods (electrodialysis and electrolysis) and membrane methods for producing PAC have been developed. The membrane method is to add alkali liquor on one side of the membrane into aluminum trichloride solution on the other side to react under the action of pressure difference, concentration difference and the like, so as to prepare PAC. The electrodialysis method is that under the action of an external electric field, an electrolytic cell is divided into three chambers, namely an anode chamber, a reaction chamber and a cathode chamber, ions are subjected to electromigration and penetrate through corresponding ion membranes, and in the reaction chamber, aluminum trichloride and migrated hydroxyl ions are subjected to polymerization reaction to generate PAC. Al can be made by a film method13The content is improved to more than 80 percent, but the total aluminum concentration is lower than 0.5 mol/L. The electrodialysis method can prepare PAC with total aluminum concentration of 0.1-1.0 mol/L, but Al13The content is not higher than 60%. Both membrane and electrodialysis methods have the difficult problem that membrane fouling is easy to occur.
The electrolytic method can prepare PAC, Al with higher quality13The content can reach 60-80%, and the total aluminum concentration is 0.1-1.0 mol/L. The preparation principle is that under the action of direct current, an anode aluminum plate is dissolved, a cathode stainless steel plate is subjected to hydrogen evolution reaction, so that alkali is slowly added into analuminum trichloride electrolyte, the electrolyte is continuously circulated through a circulating pump, and aluminum ions and hydroxyl ions are polymerized to generate PAC. The electrolytic preparation of PAC is a promising method, however, the dissolution of the anode aluminum plate during the electrolytic preparation process results in the consumption of aluminum material, which results in relatively high production costs, and thus, the need for large-scale production has not been met.
Disclosure of Invention
The purpose of the invention is as follows:
overcomes the defect of higher cost when the aluminum plate is used as the anode to prepare PAC, and ensures that the prepared PAC has high aluminum concentration and Al13The PAC content meets the requirement of industrial production and application.
The technical scheme of the invention is as follows:
in an electrochemical reactor, the Anode adopts a Dimensionally Stable Anode (DSA), titanium is used as a cathode, the electrodes adopt a single-pole parallel connection mode, the inter-pole distance of each group of electrodes is 10-90 mm, the Anode potential is controlled to be 1.3-2.0V, and the current density is 0.2-3.0A/dm2The method comprises the steps of determining electrolysis time according to the electric quantity required when the alkalization degree of the prefabricated polyaluminium chloride is reached, taking aluminum trichloride as an electrolyte, enabling the temperature of the electrolyte to be 15-60 ℃, circulating the electrolyte through a circulating pump, electrifying direct current, polymerizing hydroxyl ions generated by hydrogen evolution reaction of a cathode and trivalent aluminum ions in the electrolyte to generate PAC, and promoting the generation of high-quality PAC due to consumption of chloride ions caused by chlorine evolution of an anode. The principle is as follows:
anode main reaction:
and (3) cathode main reaction:
the total chemical reaction:
the hydroxyl ions generated by the cathode reaction are polymerized with trivalent aluminum ions in the electrolyte, which is an enhanced hydrolysis-polymerization-precipitation process of the aluminum ions, and the electrolysis time is controlled to ensure that the aluminum form stays at Al13Form is shown. The chlorine generated at the anode can also influence the process, and both chloride ions and hydroxide ions in the electrolyte can generate coordination reaction with trivalent aluminum ions, and the polymerization of the hydroxide ions and the trivalent aluminum ions can be promoted due to the consumption of the chloride ions. In addition, chlorine generated by the cathode can be partially dissolved in the electrolyte, so that the PAC flocculating agent also contains an effective chlorine component. Of course the anode may also beSide reactions occur: this is detrimental to the synthesis of PAC, however, with DSA electrodes and in more acidic chloride solutions, this reaction occurs to a limited extent and has little effect on the manufacturing process. After the electrolysis is finished, the electrolyte is aged for about 24 hours to obtain clear and transparent high-quality PAC, the alkalization degree is 2.0-2.5, and the effective flocculation component Al13The content reaches 60-90%, the total aluminum concentration reaches 0.1-1.5 mol/L, and the available chlorine content is 500-2000 ppm.
The invention has the characteristics that:
1. the DSA anode and the titanium are used as the cathode, and the two electrode materials have good corrosion resistance, high mechanical strength, low price and easy obtainment and are easy for large-scale industrial production.
2. The equipment for preparing PAC is simple and compact, can be directly used for on-site production and addition in the water treatment process, omits the storage, transportation and dissolution processes of the flocculating agent, and saves a large amount of production cost.
3. If the on-site production and the addition are carried out, the chlorine generated in the electrolysis process can be used for the disinfection step in the water treatment process, thereby saving the water treatment cost.
4. The prepared PAC has good quality and higher Al13The content and the total aluminum concentration of the aluminum alloy are not harmful impurities, and the chlorine dissolved in the solution also has the functions of sterilization, disinfection and oxidation.
5. The method is simple to operate, the preparation process is easy to control, and the synthesis of PAC can be effectively controlled only by a small amount of parameters, so that the stability of the product is ensured.
6. The preparation process flow is simple, the requirements on process conditions are low, and the preparation can be carried out at normal temperature and normal pressure.
7. And the mesh electrode is adopted, so that the gas is separated out and the mass transfer exchange of the electrolyte is facilitated.
8. The current efficiency is improved by controlling the anode potential, and the method is simple and convenient.
9. And a single-pole parallel connection mode is adopted, so that the space-time yield of PAC is improved.
Drawings
The attached drawing is a schematic diagram of a preparation device of the method for preparing the polyaluminium chloride by dimensionally stable anode electrolysis. Wherein 1 is a direct current power supply, 2 is a thermometer, 3 is an overflow tank, 4 is an electrolytic tank, 5 is a voltmeter, 6 is a titanium mesh cathode, 7 is a DSA anode, 8 is a calomel reference electrode, 9 is an aluminum trichloride electrolyte and 10 is a circulating pump.
Detailed Description
The operation process is as follows:
the preparation device is shown in the figure, aluminum trichloride solution with certain concentration is prepared according to the concentration and the alkalization degree of the prefabricated PAC, the prepared PAC is added into an electrolytic tank 4, a circuit is checked, a circulating pump 10 is started, then a power supply 1 is started, the potential value of an anode 7 to a reference electrode 8 is read at a voltmeter 5, the potential of the anode is enabled to be between 1.3 and 2.0, the temperature of electrolyte is read at a thermometer 2, when the electrolysis is completed, the power supply 1 is cut off, the circulating pump 10 is closed, and the prepared PAC is taken out.
Example (b):
example 1:
as shown in the attached drawing, 0.8L of 0.5mol/L aluminum trichloride electrolyte was added to a 1L organic glass electrolytic cell, and electrolytic production was carried out under the following conditions.
Anode: ruthenium titanium mesh with an effective electrode area of 5.4dm2(60mm×90mm)
Cathode: titanium mesh with effective electrode area of 5.4dm2(60mm×90mm)
Power supply: DC voltage-stabilizing current-stabilizing power supply
Voltage: 4.0-5.0V
Temperature: 15-40 DEG C
The pole pitch: 15mm
Current density: 1.0A/dm2
And (3) electrolysis time: 8 hours
Electrode connection mode: 4 groups of electrodes are connected in parallel in a single pole manner
And (3) analyzing the product after the electrolysis, wherein the main indexes are as follows:
total aluminum concentration: 0.56mol/L
Al13The content is as follows: 85.2 percent
Effective chlorine content: 1720ppm
Degree of alkalization: 2.32
pH：4.56
Example 2:
as shown in the attached drawing, 0.80mol/L of an aluminum trichloride electrolytic solution was added to a 1L organic glass electrolytic bath and 0.8L was prepared by electrolysis under the following conditions.
Anode: ruthenium titanium mesh with an effective electrode area of 5.4dm2(60mm×90mm)
Cathode: titanium mesh with effective electrode area of 5.4dm2(60mm×90mm)
Power supply: DC voltage-stabilizing current-stabilizing power supply
Voltage: 3.5-4.5V
Temperature: 15-45 DEG C
The pole pitch: 10mm
Current density: 1.2A/dm2
And (3) electrolysis time: 15 hours
Electrode connection mode: 4 groups of electrodes are connected in parallel in a single pole manner
And (3) analyzing the product after the electrolysis, wherein the main indexes are as follows:
total aluminum concentration: 1.06mol/L
Al13The content is as follows: 86.2 percent
Effective chlorine content: 1510ppm
Degree of alkalization: 2.19
pH：4.17
Example 3:
as shown in the attached drawing, 0.8L of 1.0mol/L aluminum trichloride electrolyte was added to a 1L organic glass electrolytic cell, and electrolytic production was carried out under the following conditions.
Anode: ruthenium titanium mesh with an effective electrode area of 5.4dm2(60mm×90mm)
Cathode: titanium mesh with effective electrode area of 5.4dm2(60mm×90mm)
Power supply: DC voltage-stabilizing current-stabilizing power supply
Voltage: 3.0-4.0V
Temperature: 15-45 DEG C
The pole pitch: 15mm
Current density: 1.5A/dm2
And (3) electrolysis time: 20 hours
Electrode connection mode: 4 groups of electrodes are connected in parallel in a single pole manner
And (3) analyzing the product after the electrolysis, wherein the main indexes are as follows:
total aluminum concentration: 1.27mol/L
Al13The content is as follows: 72.3 percent
Effective chlorine content: 1100ppm
Degree of alkalization: 1.84
pH：3.90
Claims (3)
1. The electrolytic preparation method of polyaluminium chloride is characterized by using aluminium trichloride as electrolyte, adopting dimensionally stable anode as anode and titanium as cathode, adopting unipolar parallel connection mode to alternatively arrange the electrodes, controlling the electrode spacing to be 10-90 mm and controlling the anode potential to be 1.3-2.0V so as to make the current density reach 0.2-3.0A/dm2And D, electrifying direct current for a period of time, and circulating the electrolyte to obtain the polyaluminium chloride.
2. The process according to claim 1, wherein the anodic evolution of chlorine and the cathodic evolution of hydrogen are carried out by adjusting the current density and controlling the rate of electrochemical addition of alkali to promote the hydrolytic polymerization of aluminum in the electrolyte, thus obtaining polyaluminum chloride.
3. The aqueous polyaluminum chloride solution produced by the process according to claim 1, wherein the alkalization degree is 2.0 to 2.5 and the effective flocculation component Al13The content reaches 60-90%, the total aluminum concentration reaches 0.1-1.5 mol/L, and the available chlorine content is 500-2000 ppm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CNB2003101213806A CN100393915C (en) | 2003-12-16 | 2003-12-16 | Process for preparing polymeric aluminium chloride through dimensionally stable anodes |
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| CNB2003101213806A CN100393915C (en) | 2003-12-16 | 2003-12-16 | Process for preparing polymeric aluminium chloride through dimensionally stable anodes |
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103159310A (en) * | 2011-12-15 | 2013-06-19 | 中国科学院生态环境研究中心 | Method for removal of arsenic in water based on polyaluminum chloride |
| CN103305862A (en) * | 2012-03-13 | 2013-09-18 | 温州大学 | Electrochemical production device and manufacturing method of high-alkalization-degree aluminum polychlorid and Al13 chloride |
| CN104003484A (en) * | 2014-06-18 | 2014-08-27 | 湖北工业大学 | Electric coagulation decoloring method for printing and dyeing wastewater |
| CN105132942A (en) * | 2015-08-21 | 2015-12-09 | 无锡桥阳机械制造有限公司 | Preparing technology for polymeric aluminum |
| CN106191913A (en) * | 2016-08-29 | 2016-12-07 | 太仓市新星轻工助剂厂 | A kind of preparation method of aluminium polychlorid |
| CN107324363A (en) * | 2017-07-28 | 2017-11-07 | 中国科学院生态环境研究中心 | A kind of high Al13The simple method for preparing of content aluminium polychloride |
| CN114108007A (en) * | 2020-08-31 | 2022-03-01 | 中国科学院宁波材料技术与工程研究所 | Composition for preparing hypochlorous acid water and application thereof |
| CN114772624A (en) * | 2022-05-12 | 2022-07-22 | 西安益维普泰环保股份有限公司 | Method for producing high-purity aluminum chloride |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4108972C2 (en) * | 1991-03-20 | 1995-08-17 | Air Lippewerk Recycling Gmbh | Process for increasing the molar aluminum / chlorine ratio in polyaluminum chloride solutions |
| CN1186733A (en) * | 1997-01-02 | 1998-07-08 | 林翠雯 | Production of composite fibre paper bag for cement and its making equipment |
| CN1054658C (en) * | 1997-06-20 | 2000-07-19 | 中国科学院生态环境研究中心 | Electrochemical synthesis of polymerized aluminum chloride |
-
2003
- 2003-12-16 CN CNB2003101213806A patent/CN100393915C/en not_active Expired - Lifetime
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103159310A (en) * | 2011-12-15 | 2013-06-19 | 中国科学院生态环境研究中心 | Method for removal of arsenic in water based on polyaluminum chloride |
| CN103305862A (en) * | 2012-03-13 | 2013-09-18 | 温州大学 | Electrochemical production device and manufacturing method of high-alkalization-degree aluminum polychlorid and Al13 chloride |
| CN104003484A (en) * | 2014-06-18 | 2014-08-27 | 湖北工业大学 | Electric coagulation decoloring method for printing and dyeing wastewater |
| CN105132942A (en) * | 2015-08-21 | 2015-12-09 | 无锡桥阳机械制造有限公司 | Preparing technology for polymeric aluminum |
| CN106191913A (en) * | 2016-08-29 | 2016-12-07 | 太仓市新星轻工助剂厂 | A kind of preparation method of aluminium polychlorid |
| CN107324363A (en) * | 2017-07-28 | 2017-11-07 | 中国科学院生态环境研究中心 | A kind of high Al13The simple method for preparing of content aluminium polychloride |
| CN114108007A (en) * | 2020-08-31 | 2022-03-01 | 中国科学院宁波材料技术与工程研究所 | Composition for preparing hypochlorous acid water and application thereof |
| CN114108007B (en) * | 2020-08-31 | 2023-04-25 | 中国科学院宁波材料技术与工程研究所 | Composition for preparing hypochlorous acid water and application thereof |
| CN114772624A (en) * | 2022-05-12 | 2022-07-22 | 西安益维普泰环保股份有限公司 | Method for producing high-purity aluminum chloride |
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| CN100393915C (en) | 2008-06-11 |
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