CN1261619C - Field preparation process for ferrate and its system - Google Patents
Field preparation process for ferrate and its system Download PDFInfo
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- CN1261619C CN1261619C CN 01106769 CN01106769A CN1261619C CN 1261619 C CN1261619 C CN 1261619C CN 01106769 CN01106769 CN 01106769 CN 01106769 A CN01106769 A CN 01106769A CN 1261619 C CN1261619 C CN 1261619C
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Abstract
The present invention discloses a field preparation technology for ferrate and a system thereof. The system is mainly composed of a diaphragm electrolytic tank, a circulating reactor, a flowmeter, a water sprayer, a pump, a refluxing water tank, etc. The technology comprises the following steps: saturation common salt solution is electrolyzed in the diaphragm electrolytic tank; chlorine gas generated by a positive electrode is sucked by the water sprayer, the chlorine gas is mixed with Fe (OH) 3 from the refluxing water tank, and the chlorine gas and the Fe (OH) 3 thoroughly react in the circulating reactor; through circulating reflux for a plurality of times, sodium ferrate is prepared. The present invention has the advantages that the present invention overcomes the defects that the concentration of sodium ferrate products prepared by the existing electrolysis method is low, the current efficiency is low, etc.; the operation is convenient, the stability is high, and the usability is strong; industrial production in a large batch can be directly carried out.
Description
Technical Field
The invention relates to the treatment of wastewater and drinking water, in particular to a process and a device for preparing multifunctional water treatment agent ferrate on site.
Technical Field
Ferrate is a hexavalent iron compound having the formula MFeO4(M: alkali metal or alkaline earth metal), a common compound is potassium ferrate (K)2FeO4) Sodium ferrate (Na)2FeO4). Because of the special chemical properties of ferrate, it has very high application value in the water treatment process, is a high-efficiency multifunctional water treatment chemical agent which integrates disinfection, oxidation, flocculation, adsorption and coagulation aiding and has no toxic or side effect, and has important research, development, popularization and application prospects.
The key to the use of ferrate as a highly effective water treatment agent is the synthesis of its stable product, but to date the desired results have not been achieved. There are three current methods for ferrate production: (1) hypochlorite oxidation process; (2) a hot melting method; (3) electrolysis. Because the hypochlorite oxidation method and the hot melting method have complex preparation processes, the operation process is difficult to control, and ferrate has strong oxidizability and is easy to decompose, the current scholars tend to develop the field preparation process, and the electrolysis method is representative of the processes. The patent 4435256, 4435257 in 1984 discloses a process for preparing ferrate by electrolysis. However, the electrolytic process still has the following disadvantages:
a. the product concentration is low. Na (Na)2FeO4The concentration of the alkaline saturated solution is about 20g/l, and most of the results are lower than 5g/l at present and far from reaching saturation.
b. The current efficiency is low and unstable, and the operation stability is poor. The current efficiency is lower than 50% under most conditions, and the highest current efficiency is difficult to stably maintain and is easily influenced by factors such as potential, current density and temperature.
c. The whole electrolysis process has strict requirements on equipment and raw materials. If a film with special performance is required, reducing impurities in the raw materials must be strictly excluded, and the like. For the above reasons, existing electrolyzers are all on a laboratory scale.
Disclosure of Invention
The invention aims to prepare high-concentration ferrate and develop a process and a device for preparing the ferrate on site.
The technical solution of the invention is realized as follows:
the preparation process of the invention is as follows: the saturated salt solution is electrolyzed in a diaphragm electrolytic cell (1), chlorine gas generated at an anode (2) is absorbed by a water ejector (11) and is mixed with Fe (OH) from a return water tank (13)3Mixing, and fully reacting in a loop reactor (8); NaOH solution obtained in the cathode (4) area can be sent into a reflux water tank (13) through a pipeline to participate in the preparation of FeCl3+ NaOH solution. The chlorine escaping from the loop reactor (8) is sent into the reflux water tank (13) by a pipeline (20) and is cooled by Fe (OH) in the reflux water tank (13)3Absorbing by the solution; the reaction mixed liquid in the circulation flow reactor (8) flows back to the reflux water tank (13) through a pipeline (19), then enters the circulation flow reactor (8) through a pump (12) and a flow meter (9), and circulates and refluxes for a plurality of times until ferrate solution with specified concentration is obtained, and is discharged from the reflux water tank (13).
FeCl in feed liquid preparation3The amount of the catalyst is 10-40 g/l.
Cl2And Fe (OH)3During the reaction, the concentration of NaOH is 5-14 mol/l.
The chlorine used in the process can be prepared by electrolysis or can be provided by a chlorine bottle.
In the technical scheme, the reflux water tank (13) is Fe (OH)3The feed liquid preparation tank is also an intermediate collecting tank and a final discharging tank of the ferrate product.
The preparation device of the on-site preparation process comprises the following steps: mainly comprises a diaphragm electrolytic tank (1), a loop reactor (8), a flowmeter (9), a water ejector (11), a pump (12), a reflux water tank (13) and the like. An anode (2), a diaphragm (3) and a cathode (4) are arranged in the diaphragm electrolytic cell (1). The upper end of the anode chamber of the electrolytic cell (1) is provided with a gas outlet, the outlet is connected with a gas inlet (25) of a water injector (11) through a gas pipeline (7), the lower end of the cathode chamber of the electrolytic cell (1) is provided with a solution outlet, and the solution outlet is connected with a backflow water tank (13) through a pipeline (22) and a valve (16). The loop reactor(8) mainly comprises an inner loop (24), an outer loop (23) and a water ejector (11); a water injector (11) is fixed on a bottom plate (26) of the circulation reactor (8), an exhaust pipe (29) is arranged on a top cover (28) of the circulation reactor, a liquid outlet (27) is arranged at the upper end of the circulation reactor, the liquid outlet (27) is connected with a reflux water tank (13) through a pipeline (19), and the exhaust pipe (29) is connected with the bottom of the reflux water tank (13) through a pipeline (20); the bottom of the backflow water tank (13) is provided with a solution circulation port which is connected with the lower end of the water ejector (11) through a pump (12) and a flowmeter (9), and the backflow water tank (13) is also provided with a liquid discharge valve (21).
The diameter of the outer loop (23) of the loop reactor (8) is DRThe diameter of the inner collar (24) is DE，The height of the inner ring pipe is L; the ratio of the diameter of the inner ring pipe to the diameter of the outer ring pipe is DE/DR0.5-0.8, the ratio of the height of the inner ring pipe to the diameter of the outer ring pipe is L/DR＝2～5。
The anode (2) of the diaphragm electrolytic cell (1) adopts reticular RuO-Ti or graphite, the cathode (4) adopts an iron net, and the polar distance is 10-25 mm. The packing density of the polar plate is 0.01-0.03 cm2/cm3Current density of 4-9A/dm2. The diaphragm (3) in the diaphragm electrolytic tank (1) is a polymer ion exchange membrane or a modified asbestos diaphragm.
The process and the device thereof can also be used for preparing potassium ferrate.
Compared with the prior art, the invention has the following advantages:
the defects of low concentration, low current efficiency and the like of the sodium ferrate prepared by the existing electrolytic method are overcome, and a new breakthrough is made in the preparation process; chlorine produced by electrolysis and Fe (OH)3The ferrate is prepared by fully reacting in a loop reactor (8) and circulating for many times, so that the concentration of the prepared ferrate solution can reach 20-30 g/l. The invention removes the complex procedures of purifying the solid products by a hypochlorite oxidation method, and greatly reduces the material consumption. The invention is convenient to operate, has high stability and strong usability, and can be directly used for large-batch industrial production.
Drawings
The invention is described in further detail below with reference to the accompanying drawings:
FIG. 1 is a schematic flow diagram of the in situ preparation process of the present invention;
FIG. 2 is a schematic diagram of the loop reactor configuration of the present invention.
Example (b):
sodium ferrate (Na)2FeO4) The chemical reaction equation of the preparation process is as follows:
the device for preparing the sodium ferrate solution on site is shown in figure 1, and the principle of the preparation device is shown in figure 3. The device mainly comprises a diaphragm electrolytic tank 1, a loop reactor 8, a flowmeter 9, a water ejector 11, a pump 12, a reflux water tank 13 and the like. The anode of the diaphragm electrolytic cell 1 adopts reticular RuO-Ti or graphite, the cathode 4 adopts an iron net, and the polar distance is 10-25 mm. A polymer ion exchange membrane 3 is arranged between the anode 2 and the cathode 4. The packing density of the polar plate is 0.01-0.03 cm2/cm3The current density is 4-9A/dm2。
The anode 2 and the cathode 4 of the diaphragm electrolyzer 1 are connected to a direct current power supply 5. The upper end of the anode 2 of the diaphragm electrolytic cell 1 is provided with a gas outlet which is connected with a gas inlet 25 of the water injector 11 through a gas pipeline 7 so that Cl generated by the anode 2 is enabled2Is sucked by the water ejector 11. The lower end of the cathode chamber of the electrolytic cell 1 is provided with solutionAn outlet connected with the reflux water tank 13 through a pipeline 22; the alkali liquor (NaOH) obtained from the cathode zone 4 is returned to the reflux water tank 13 and added into the preparation feed liquid.
An exhaust pipe 29 is arranged on the top cover 28 of the loop reactor 8, the exhaust pipe 29 is connected with the bottom of the reflux water tank 13 through a pipeline 20, so that chlorine gas escaping from the loop reactor 8 is treated by Fe (OH) in the reflux water tank 133The solution is absorbed and utilized. The upper end of the circulation reactor 8 is provided with a liquid outlet 27, and the liquid outlet 27 is connected with a reflux water tank through a valve 10, a pipeline 19 and a reflux water tank13 are connected. The bottom of the backflow water tank 13 is provided with a solution circulation port which is connected with the lower end of the water ejector 11 through a pump 12, a valve 15, a valve 14 and a flowmeter 9.
A liquid discharge valve 21 is also arranged on the reflux water tank 13 and is used for taking out the prepared sodium ferrate solution; and the slag discharging valve 18 is used for cleaning impurities.
See fig. 2. The loop reactor 8 is mainly composed of an inner loop 24, an outer loop 23 and a water ejector 11. The top 28 of the loop reactor 8 is provided with a vent pipe 29, and the bottom plate 26 is fixed with a water ejector 11.
The outer loop 23 of the loop reactor 8 has a diameter DRThe diameter of the inner ring pipe 24 is DEAnd the height of the inner ring pipe is L. The distance between the top end of the inner collar 24 and the lower edge of the top cover 28 is L1, and the distance between the bottom of the inner collar 24 and the upper edge of the bottom plate 26 is L2. The main size proportion between the inner ring pipe and the outer ring pipe is as follows: dE/DR＝0.5～0.8，L/DR＝2～5，L1/DR＝0.3～0.5，L2/DR＝0.2～0.4。
The preparation process comprises the following steps:
1. connecting the equipment devices: the equipment set is connected according to the process flow shown in figure 1.
2. Preparing materials: according to FeCl3The consumption is 40g/l, and the NaOH consumption is 14 mol/l. Using tap water to mix FeCl3And (4) completely dissolving, adding solid NaOH, and adding tap water into the solution to dilute the solution to 21. Cooled to room temperature, and the solution was poured into a reflux water tank 13. The water pump 12 was started and the valve 15 and the valve 17 were adjusted so that the flow into the loop reactor 8 was 170 l/h.
3. Starting the device, carrying out gas-liquid reaction: 300g/l NaCl solution was added to the cell 1 and HCl adjusted to pH 3. Turning on the DC power supply 5 to Cl2Occurs stably. The valves 17 and 15 are adjusted to control the flow rate, so that the loop reactor 8 operates normally. Na is continuously circulated and flowed through the circulating reactor 8, the valve 10, the pipeline 19, the reflux water tank 13, the pump 12, the valve 17, the valve 15 and the flowmeter 9 to ensure that the Na2FeO4The solution concentration is continuously increased.
4. And (3) cyclic reaction: circulating reflux for about 300min to obtain the product with the concentration of 25 to30g/l of Na2FeO4The finished solution product can be taken out through the valve 21 of the reflux water tank 13 for use.
Na prepared using in situ preparation process2FeO4The solution has very obvious treatment effect on explosive waste water, hospital sewage and EDTA copper-containing waste water. For example:
(1) treating explosive destruction wastewater with TNT content of 105mg/l, and adding Na2FeO4When the amount is 100mg/l, the reaction time is 45min, the TNT concentration is reduced to 0.30mg/l, and the national first-class emission standard (0.5mg/l) can be achieved.
(2) For EDTA complex copper-containing wastewater which can not be treated by neutralization precipitation method and reaches the standard, Na is used2FeO4Pre-oxidation is carried out, Na2FeO4The dosage is 700mg/l, the reaction time is 30min, and Cu is precipitated through neutralization2+The concentration is reduced from 52.0mg/l to 0.42mg/l, which can reach the national first-class emission standard (0.5 mg/l).
Claims (10)
1. A ferrate on-site preparation process is characterized in that: the saturated salt solution is electrolyzed in a diaphragm electrolytic cell (1), chlorine gas generated at an anode (2) is absorbed by a water ejector (11) and is mixed with Fe (OH) from a return water tank (13)3Mixing, and fully reacting in a loop reactor (8); NaOH solution obtained in the cathode (4) area is sent into a reflux water tank (13) through a pipeline (22) to participate in the preparation of FeCl3+ NaOH feed liquid; the chlorine escaping from the loop reactor (8) is sent into the reflux water tank (13) by a pipeline (20) and is cooled by Fe (OH) in the reflux water tank (13)3Absorbing by the solution; the reaction mixed liquid in the circulation flow reactor (8) flows back to the reflux water tank (13) through a pipeline (19), then enters the circulation flow reactor (8) through a pump (12) and a flow meter (9), and circulates and refluxes for a plurality of times until ferrate solution with specified concentration is obtained, and is discharged from the reflux water tank (13).
2. The process according to claim 1, characterized in that: FeCl in feed liquid preparation3The amount of the catalyst is 10-40 g/l.
3. The process according to claim 1, characterized in that: cl2And Fe (OH)3During the reaction, the concentration of NaOH is 5-14 mol/l.
4. The process according to claim 1, characterized in that: the filling density of the polar plate of the diaphragm electrolytic cell (1) is 0.01-0.03 cm2/cm3Current density of 4-9A/dm2。
5. The process according to claim 1, characterized in that: the chlorine used in the process is produced electrolytically or is supplied from chlorine bottles.
6. The manufacturing apparatus of the manufacturing process according to one of claims 1 to 5, characterized inthat: the device mainly comprises a diaphragm electrolytic tank (1), a loop reactor (8), a flowmeter (9), a water ejector (11), a pump (12) and a reflux water tank (13); the upper end of the anode chamber of the diaphragm electrolytic cell (1) is provided with a gas outlet which is connected with a gas inlet (25) of the water injector (11) through a gas pipeline (7), the lower end of the cathode chamber of the electrolytic cell (1) is provided with a solution outlet which is connected with a water return tank (13) through a pipeline (22) and a valve (16); a liquid outlet (27) of the loop reactor (8) is connected with the reflux water tank (13) through a pipeline (19), and an exhaust pipe (29) of the loop reactor (8) is connected with the bottom of the reflux water tank (13) through a pipeline (20); the bottom of the backflow water tank (13) is provided with a solution circulation port which is connected with the lower end of the water ejector (11) through a pump (12) and a flowmeter (9), and the backflow water tank (13) is also provided with a liquid discharge valve (21).
7. The manufacturing apparatus according to claim 6, wherein: an anode (2), a diaphragm (3) and a cathode (4) are arranged in the diaphragm electrolytic cell (1); the diaphragm (3) is a high-molecular ion exchange membrane or a modified asbestos diaphragm.
8. The manufacturing apparatus according to claim 6, wherein: the loop reactor (8) mainly comprises an inner loop (24), an outer loop (23) and a water ejector (11); a water injector (11) is fixed on a bottom plate (26) of the circulation reactor (8), an exhaust pipe (29) is arranged on a top cover (28) of the circulation reactor, and a liquid outlet (27) is arranged at the upper end of the circulation reactor.
9. The manufacturing apparatus according to claim 6 or 7, characterized in that: the anode (2) of the diaphragm electrolytic cell (1) adopts reticular RuO-Ti or graphite, the cathode (4) adopts an iron net, and the polar distance is 10-25 mm.
10. The manufacturing apparatus according to claim 6 or 8, characterized in that: the diameter of the outer loop (23) of the loop reactor (8) is DRThe diameter of the inner collar (24) is DEThe height of the inner ring pipe is L; the ratio of the diameter of the inner ring pipe to the diameter of the outer ring pipe is DE/DR0.5-0.8, the ratio of the height of the inner ring pipe to the diameter of the outer ring pipe is L/DR＝2～5。
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 01106769 CN1261619C (en) | 2001-02-27 | 2001-02-27 | Field preparation process for ferrate and its system |
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| Application Number | Priority Date | Filing Date | Title |
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| CN 01106769 CN1261619C (en) | 2001-02-27 | 2001-02-27 | Field preparation process for ferrate and its system |
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| CN1329182A CN1329182A (en) | 2002-01-02 |
| CN1261619C true CN1261619C (en) | 2006-06-28 |
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| CN 01106769 Expired - Fee Related CN1261619C (en) | 2001-02-27 | 2001-02-27 | Field preparation process for ferrate and its system |
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Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2641998A1 (en) * | 2004-01-16 | 2013-09-25 | Battelle Memorial Institute | Apparatus for producing ferrate (VI) |
| CN101713078B (en) * | 2009-09-22 | 2015-04-15 | 上海市政工程设计研究总院 | Device and method for preparing potassium ferrate through electrolysis |
| US8961921B2 (en) * | 2009-09-28 | 2015-02-24 | Florida Institute Of Technology | Apparatus and method for producing liquid ferrate |
| CN101838035B (en) * | 2010-05-11 | 2011-09-21 | 沈阳建筑大学 | Preparation method of sodium ferrate-beta-cyclodextrin inclusion compound |
| CN103058281A (en) * | 2013-01-06 | 2013-04-24 | 东北电力大学 | Process and device used for preparing ferrate salt with on-line wet chemical method |
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