CN1186773A - Preparing polymerised aluminum chloride by electrodialysis - Google Patents
Preparing polymerised aluminum chloride by electrodialysis Download PDFInfo
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- CN1186773A CN1186773A CN97122054A CN97122054A CN1186773A CN 1186773 A CN1186773 A CN 1186773A CN 97122054 A CN97122054 A CN 97122054A CN 97122054 A CN97122054 A CN 97122054A CN 1186773 A CN1186773 A CN 1186773A
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- aluminum
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- polyaluminium chloride
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Abstract
The present invention belongs to the technological field of the production and application of water treating chemical. By using aluminium trichloride as electrolyte, two sheets of anionic exchange film to constitute the reactor, graphite as anode, and porous plate as cathode and applying DC current for certain period, the water solution of polymerised aluminium chloride is produced. Compared with available polymerised aluminium, the said process has reduced production cost and improved product quality. Flocculation test shows that the present invention is superior to aluminium sulfate and other traditional flocculant in the flocculation effect.
Description
The invention relates to a preparation method of a flocculating agent for water treatment, in particular to a preparation method of polyaluminium chloride with high alkalization degree and high content of effective component Alb.
In water treatment, flocculating agents are used for removing suspended and dispersed colloid impurities in water, and the adopted flocculating agents comprise common inorganic flocculating agents such as aluminum sulfate, ferric trichloride and the like, inorganic polymeric flocculating agents such as polyaluminum chloride, polyaluminum sulfate and the like, and organic polymeric flocculating agents such as polyacrylamide and the like.
The aluminum sulfate flocculating agent is low in price, but the formed floc is small, the aggregation and sedimentation speed is low, the dosage of the agent and the residual amount of aluminum in the treated water are relatively high, and the adverse effect on the health of a human body is brought. The use of aluminium sulphate enables the alkalinity of the water to be greatly reduced and in some cases must be used with large amounts of alkaline chemicals or other coagulant aids.
Ferric trichloride can form larger floccules after being treated by water and can generate effective coprecipitation with heavy metal ions, but ferric salts such as ferric trichloride have strong corrosivity to metals and low stability, hydrated lime is required to be added as a coagulant aid in the using process, and a large amount of sludge can be generated.
Polyacrylamide and other organic polymeric flocculants can form larger flocs at a higher speed, but the organic flocculants have the disadvantages of higher price and difficulty in ensuring the safety and non-toxicity of the treated water.
Polyaluminum chloride has a high flocculating ability, and its amount is only one-half to one-third of aluminum sulfate, and it is widely used because the floc formation speed in low-temperature water is high and the residual aluminum content in water after treatment is low.
The following methods are generally used for preparing the polyaluminium: 1. chemical method using aluminium or aluminium-containing material (including aluminium ash, aluminium oxide extracted from clay ore or coal gangue, etc.) as raw material. The main components of the aluminum ash or the aluminum are aluminum and aluminum oxide which can carry out violent exothermic reaction with hydrochloric acid, and the principle is as follows:
In addition, there is a method for treating an acidic waste liquid containing aluminum and preparing alkaline polyaluminum chloride by an electrolytic process. (Showa 50-46598).
2. A method for preparing sodium aluminate or aluminum hydroxide. Sodium aluminate or aluminum hydroxide and a certain proportion of hydrochloric acid react in a reaction kettle to generate polyaluminum chloride, and the product quality is basically determined by the charging ratio of reactants (Japanese patent laid-open No. Sho 45-38121; Sho 53-1240).
In the two methods, the quality of the product is unstable, the alkalization degree in the product quality index can only reach 40-50 percent, and the main effective flocculation component Alb (Al) is an Al component, because the raw materials for producing the polyaluminium chloride have various types and complex components, the production conditions require high temperature and high pressure, the production process is long, and the generation process of the polyaluminium chloride is basically uncontrollable13Polymeric state) content is low and unstable, so it is difficult toobtain products having the same degree of polymerization by controlling the same process conditions. Influenced by raw materials, the product has high impurity content, and the production waste gas easily causes environmental pollution.
3. A production method using aluminum trichloride as a raw material. The following three methods are mainly used:
(1) and (4) a neutralization method. Adding alkaline substances such as sodium hydroxide, lime, limestone, sodium carbonate and the like into an aluminum trichloride solution to improve the concentration of hydroxide ions so as to promote the hydrolysis of the aluminum trichloride, and obtaining polymeric aluminum products with different alkalinization degrees by different alkali adding amounts according to the following principle:
(2) Electrodialysis (Japanese Kokai Sho 49-24353; Sho 49-24354; Sho 49-24355;). The method utilizes the principles of water electrolysis and selective permeation of ion exchange membranes, and uses an anion exchange membrane and a special cation exchange membrane to form a reaction chamber. The method prepares the polyaluminium chloride by taking the aqueous solution of the aluminium trichloride as a raw material, the product quality completely depends on the quality of a cation exchange membrane, and the cost of the method is higher because the cation exchange membrane is higher in price.
(3) Thermal decomposition (Showa 49-43477; Showa 49-43478; West German patent No1102713[1961]). The aluminum trichloride crystal is subjected to decomposition reaction under the heating condition to generate polyaluminium chloride:
In summary, due to the defects of the existing method for producing the polyaluminium chloride, the quality of commercial polyaluminium chloride is not high, the alkalinization degree of main performance indexes is 40-50%, and the main effective flocculation component Alb (Al) is13) The content of the flocculant is generally less than 45 percent, and the polyaluminium chloride can not play the due high-efficiency flocculation effect.
The invention aims to overcome the defects in the current preparation of polyaluminium chloride, and provides a high-alkalization-degree high-Alb (Al) by adopting an electrochemical principle13) A method for synthesizing polyaluminium chloride with excellent flocculation performance and a product thereof.
The method of the invention is a process for preparing polyaluminium chloride with high alkalization degree and high Alb content by utilizing trivalent aluminium ions to controllably and effectively carry out polymerization reaction with hydroxide ions generated under electrochemical conditions in a special electrochemical reactor. The aluminum ions come from the aluminum trichloride solution in the reaction chamber, and hydroxide ions from the cathode chamber penetrate through the anion exchange membrane to enter the reaction chamber. The specific method comprises the following steps:
as shown in the attached drawing, the electrolytic cell is divided into threechambers, namely an anode chamber, a reaction chamber and a cathode chamber, by two anion exchange (heterogeneous) membranes, and according to the content of the prefabricated product aluminum and the alkalization degree, an aluminum trichloride solution with a certain concentration is added into the reaction chamber of the electrolytic cell, the temperature of the electrolyte is 15-60 ℃, and the PH is 3.0-4.5. The method is characterized in that a reaction chamber is formed by two anion exchange membranes, inert electrodes such as a graphite plate, a titanium ruthenium net and the like are used as anodes, and materials such as a porous iron plate, a platinum sheet and the like are used as cathodes; the distance between the electrode and the adjacent film is 1-9 cm, and the current density is 0.5-5A/dm2. The solution is intensively stirred in the reaction chamber at a constant speed so as to increase the mass transfer of the solution and eliminate concentration polarization. Direct currentThe voltage of the electrolytic bath is 2.0-20V, which is provided by a silicon rectifying power supply. The electrolysis time is 2.5-11 hours. The alkalization degree of the prepared polyaluminum chloride is about 60%, the effective aluminum Alb content is about 60%, and the total aluminum concentration is 0.2-1.0M. The electrochemical principle of the invention is as follows:
and (3) anode reaction: (ii) a Or
And (3) cathode reaction:
while the above reaction is taking place, under the action of the DC electric field, anions (OH) in the cathode chamber-) The anion exchange membrane moves to the anode direction and enters the reaction chamber and Al3+The solution is subjected to neutralization reaction, so that an aqueous solution of polyaluminium chloride is generated; at the same time, part of Cl in the reaction chamber-And then the electrolyte migrates to the anode chamber under the action of the electric field. In the electromigration process, the electrolyzer adopts two anion exchange membranes which are characterized in that only anions are allowed to selectively permeate but cations are not allowed to permeate, so cations (such as Al) in the anode chamber and the reaction chamber3+) Will not penetrate through the anion exchange membrane into the adjacent reaction chamber or polar chamber. The chemical reaction within the reaction chamber is therefore:
in the above formula, Alm(OH)nCl3m-nI.e. polyaluminium chloride, nCl-Migrating to the anode chamber.
The invention is characterized in that:
(1) the present invention is more economical to manufacture by using conventional anion exchange (heterogeneous) membranes, which are much cheaper than the previously described tailor-made cations that only allow monovalent cations to permeate.
(2) The product prepared by the invention has no impurity sodium chloride, and the product purity is very high.
(3) The invention adopts sodium hydroxide solution as electrode solution in the cathode chamber, ensures that ions transferred from the cathode chamber to the reaction chamber are only hydroxide ions, thereby ensuring the purity of the polyaluminium chloride product
(4) The preparation process flow is simple, the requirement on process conditions is low, the production and preparation can be carried out at normal temperature and normal pressure, and high-temperature and high-pressure conditions and equipment are not needed.
(5) The preparation process is easy to control, and the generation process of the polymeric aluminum can be effectively controlled only by adjusting a small amount of parameters, so that the stability of the product quality is ensured.
(6) The equipment for preparing the polyaluminium chloride is compact, can be directly used for on-site production and addition in the water treatment process, and omits the storage, dissolution and transportation processes of water treatment agents, thereby saving a large amount of production cost.
(7) The effective components and the alkalization degree of the polyaluminium chloride product are obviously superior to those of the products prepared by the existing preparation method.
(8) Compared with the polyaluminium chloride prepared by the existing method, the flocculation effect is obviously improved.
One of the embodiments of the invention:
in an electrolytic cell shown in the attached figure, 0.1mol/L sodium sulfate aqueous solution is added into an anode chamber; 0.26mol/L AlCl is added into the reaction chamber3600 ml of the aqueous solution was added to the reaction chamber while starting stirring, and a 0.1mol/L aqueous solution of sodium hydroxide was added to the cathode chamber to conduct direct current electrolysis under the following conditions:
electrode anode: graphite plate 100X 1mm (under liquid level)
Cathode: porous iron plate 100X 1mm (below liquid level)
Electrode-to-film spacing: 2.0cm
Current intensity: 1A
Voltage: 11-12V
Temperature: 18-45 DEG C
And (3) electrolysis time: immediately after 9.2 hours of electrolysis, the final electrolyte was analyzed, and the prepared polyaluminium chloride had the following main indexes:
total aluminum concentration: 0.26mol/L
Degree of alkalization: 60.6 percent
The content of Alb: 60.92% is calculated, and the current efficiency is 82.64%.
The electrolyte was allowed to stand for 24 hours and contained a small amount of precipitate (analyzed to contain less than 5% aluminum than the total amount of aluminum in the electrolyte), and the results were reanalyzed as follows:
total aluminum concentration: 0.26mol/L
Degree of alkalization: 60.6 percent
The content of Alb: 61.8% of a second embodiment of the invention:
in an electrolytic cell shown in the attached figure, 0.4mol/L sodium sulfate aqueous solution is added into an anode chamber; 1.04mol/L AlCl is added into the reaction chamber3300 ml of an aqueous solution was added to the reaction chamber while starting stirring, and a 0.4mol/L aqueous solution of sodium hydroxide was added to the cathode chamber to conduct direct current electrolysis under the following conditions:
electrode anode: graphite plate 50X 100X 1mm (under liquid level)
Cathode: porous iron plate 50X 100X 1mm (below liquid level)
Electrode-to-film spacing: 2.0cm
Current intensity: 2A
Voltage: 20V
Temperature: 18-60 deg.C
And (3) electrolysis time: immediately after 9.2 hours of electrolysis, the final electrolyte was analyzed, and the prepared polyaluminium chloride had the following main indexes:
total aluminum concentration: 1.04mol/L
Degree of alkalization: 62.3 percent
The content of Alb: 60.50% is calculated, and the current efficiency is 85%.
The electrolyte was allowed to stand for 24 hours and contained a small amount of precipitate (analyzed to contain less than 5% aluminum than the total amount of aluminum in the electrolyte), and the results were reanalyzed as follows:
total aluminum concentration: 1.04mol/L
Degree of alkalization: 62.3 percent
The content of Alb: 61.5 percent
To verify the flocculation performance of the product prepared by the invention, the product is prepared by using the commercial polyaluminium chloride (Al, a product of Dongchang company in Tangshan, China)2O3% is 17.6, alkalization degree is 50%), the invention is used for preparing polyaluminium (hereinafter referred to as E-PAC) and aluminium trichloride (AlCl)3) Aluminum sulfate (Al)2(SO4)3·18H2O) performance comparison tests were carried out under the following test conditions:
test object liquid: suspension containing 200mg/L of kaolin, turbidity: 121.9NTU, pH 7.1
The experimental steps are as follows: the coagulation test was performed on a six-up coagulation mixer. Using 500mL of suspension each time, using four 500mL beakers as a group, and then simultaneously and respectively adding four flocculants into the four beakers to ensure that the concentration of the flocculants in the suspension is 10-5M (with aluminum Al)3+Metering), stirring rapidly (200r/min) for 30 seconds, then stirring slowly for 10min (40r/min), standing for 10-15 min, taking supernatant, and measuring turbidity respectively. Measurement of turbidity: a light scattering turbidimeter type NDH-20, Japan, was used, and the turbidity units were NTU.
The experimental steps are as follows: the coagulation test was performed on a six-up coagulation mixer. Using 500mL of suspension each time, using four 500mL beakers as a group, and then simultaneously and respectively adding four flocculants into the four beakers to ensure that the concentration of the flocculants in the suspension is 10-5M (with aluminum Al)3+Metering), stirring rapidly (200r/min) for 30 seconds, then stirring slowly for 10min (40r/min), standing for 10-15 min, taking supernatant, and measuring turbidity respectively. Measurement of turbidity: a light scattering turbidimeter type NDH-20, Japan, was used, and the turbidity units were NTU. The experimental results are as follows:
turbidity of suspension (NTU) 121.9121.9121.9121.9
Flocculant class PAC E-PAC AlCl commercially available3Al2(SO4)3
Flocculant addition concentration 10-510-510-510-5
(with aluminum Al)3+Meter) M
Turbidity 23.520.461.658.9 of supernatant after flocculation
(NTU)
From the above results, it can be seen that the polyaluminum chloride prepared by the present invention has comparable flocculation effect with commercial polyaluminum chloride, and has obvious superiority in flocculation performance compared with other water treatment agents.
Claims (3)
1. A process for preparing polyaluminium chloride features that a reaction chamber is composed of two anionic exchange membranes, the inert electrodes such as graphite plate and Ti-Ru net are used as anode, the porous iron plate and Pt plate are used as cathode, and the aqueous solution of aluminium trichloride or aluminium sulfate is used as raw material and a certain time of DC current is applied to it.
2. An aqueous solution of a water treatment agent, namely an aqueous solution of polyaluminium chloride, is characterized in that the alkalization degree is 60%, the content of an effective flocculation component Alb reaches 60%, and the aluminum concentration of the polyaluminium chloride is 0.1-1.0M.
3. The solution characteristics of the electrode chamber of the method are as follows: the cathode chamber adopts 0.05-1.0M sodium hydroxide aqueous solution, and the anode chamber adopts aqueous solution of strong electrolyte such as sodium chloride, aluminum chloride or sodium sulfate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN97122054A CN1055066C (en) | 1997-12-19 | 1997-12-19 | Preparing polymerised aluminum chloride by electrodialysis |
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| CN97122054A CN1055066C (en) | 1997-12-19 | 1997-12-19 | Preparing polymerised aluminum chloride by electrodialysis |
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2007082122A2 (en) * | 2006-01-06 | 2007-07-19 | Nextchem, Llc | Polyaluminum chloride and aluminum chlorohydrate, processes and compositions: high-basicity and ultra high-basicity products |
| WO2007082123A2 (en) * | 2006-01-06 | 2007-07-19 | Next Chem | Polymetal hydroxychloride processes and compositions: enhanced efficacy antiperspirant salt compositions |
| CN101437753B (en) * | 2006-01-06 | 2013-02-06 | 耐克斯特凯姆股份有限公司 | Polyaluminum chloride and aluminum chlorohydrate, processes and compositions: high-basicity and ultra high-basicity products |
| CN104743593A (en) * | 2013-12-31 | 2015-07-01 | 重庆蓝洁广顺净水材料有限公司 | Solid polyaluminium chloride production system |
| WO2016179786A1 (en) * | 2015-05-11 | 2016-11-17 | 毕世飞 | Method of preparing ferric salt |
| CN111077186A (en) * | 2019-12-30 | 2020-04-28 | 浙江理工大学 | Method for judging flocculation mechanism according to flocculant adding amount and Zeta potential value change |
| CN113979524A (en) * | 2021-11-12 | 2022-01-28 | 济南大学 | Preparation method of titanium polychloride |
| 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 |
| CN114988450A (en) * | 2022-06-17 | 2022-09-02 | 湖北世纪卓霖科技有限公司 | Water treatment centralized station system |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SE8900478L (en) * | 1989-02-13 | 1990-08-14 | Boliden Kemi Ab | PROCEDURES FOR PREPARING POLYALUMINUM COMPOUNDS |
| DE4202937C2 (en) * | 1992-02-01 | 1995-10-26 | Air Lippewerk Recycling Gmbh | Process for the preparation of basic aluminum chloride solutions |
-
1997
- 1997-12-19 CN CN97122054A patent/CN1055066C/en not_active Expired - Fee Related
Cited By (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2007082122A2 (en) * | 2006-01-06 | 2007-07-19 | Nextchem, Llc | Polyaluminum chloride and aluminum chlorohydrate, processes and compositions: high-basicity and ultra high-basicity products |
| WO2007082123A2 (en) * | 2006-01-06 | 2007-07-19 | Next Chem | Polymetal hydroxychloride processes and compositions: enhanced efficacy antiperspirant salt compositions |
| WO2007082122A3 (en) * | 2006-01-06 | 2008-01-03 | Nextchem Llc | Polyaluminum chloride and aluminum chlorohydrate, processes and compositions: high-basicity and ultra high-basicity products |
| WO2007082123A3 (en) * | 2006-01-06 | 2008-01-03 | Next Chem | Polymetal hydroxychloride processes and compositions: enhanced efficacy antiperspirant salt compositions |
| US7846318B2 (en) | 2006-01-06 | 2010-12-07 | Nextchem, Llc | Polyaluminum chloride and aluminum chlorohydrate, processes and compositions: high-basicity and ultra high-basicity products |
| EP2418171A1 (en) * | 2006-01-06 | 2012-02-15 | Nextchem | Method for increasing the hydroxide content of polymetal hydroxychlorides used as antiperspirant salt compositions with enhanced efficacy |
| CN101437753B (en) * | 2006-01-06 | 2013-02-06 | 耐克斯特凯姆股份有限公司 | Polyaluminum chloride and aluminum chlorohydrate, processes and compositions: high-basicity and ultra high-basicity products |
| US8801909B2 (en) | 2006-01-06 | 2014-08-12 | Nextchem, Llc | Polymetal hydroxychloride processes and compositions: enhanced efficacy antiperspirant salt compositions |
| CN104743593A (en) * | 2013-12-31 | 2015-07-01 | 重庆蓝洁广顺净水材料有限公司 | Solid polyaluminium chloride production system |
| CN104743593B (en) * | 2013-12-31 | 2017-10-20 | 重庆蓝洁广顺净水材料有限公司 | Solid polyaluminium chloride process units |
| WO2016179786A1 (en) * | 2015-05-11 | 2016-11-17 | 毕世飞 | Method of preparing ferric salt |
| CN106660824A (en) * | 2015-05-11 | 2017-05-10 | 毕世飞 | Method of preparing ferric salt |
| CN106660824B (en) * | 2015-05-11 | 2019-01-18 | 毕世飞 | The method for preparing molysite |
| CN111077186A (en) * | 2019-12-30 | 2020-04-28 | 浙江理工大学 | Method for judging flocculation mechanism according to flocculant adding amount and Zeta potential value change |
| CN113979524A (en) * | 2021-11-12 | 2022-01-28 | 济南大学 | Preparation method of titanium polychloride |
| 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 |
| CN114988450A (en) * | 2022-06-17 | 2022-09-02 | 湖北世纪卓霖科技有限公司 | Water treatment centralized station system |
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| CN1055066C (en) | 2000-08-02 |
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