CN108940183B - Method for preparing magnetic adsorbent by using waterworks ferro-manganese sludge as raw material - Google Patents
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- B01J2220/00—Aspects relating to sorbent materials
- B01J2220/40—Aspects relating to the composition of sorbent or filter aid materials
- B01J2220/48—Sorbents characterised by the starting material used for their preparation
- B01J2220/4875—Sorbents characterised by the starting material used for their preparation the starting material being a waste, residue or of undefined composition
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Abstract
The invention discloses a method for preparing a magnetic adsorbent by taking iron-manganese sludge of a water plant as a raw material, belonging to the technical field of environmental engineering. The iron mud is subjected to hydrothermal reaction after the alkalinity is adjusted and sodium ascorbate is added. And detecting the concentration of carbonate ions in the hydrothermal reaction to obtain an inflection point and a characteristic peak of the generation potential of the carbonate ions. And after the process controller identifies the inflection point and the characteristic peak, sending an instruction to turn off a power supply control system to stop the hydrothermal reaction. The method for preparing the magnetic adsorbent by using the waterworks ferro-manganese sludge as the raw material can adapt to the change of ferro-manganese content in the iron sludge, and can directly obtain the magnetic material with good magnetic response and high adsorption performance by adjusting the hydrothermal reaction time and the reagent addition amount in real time under the conditions of not detecting the element composition in the iron sludge and not carrying out batch hydrothermal experiments, and the method is simple and low in price.
Description
Technical Field
The invention relates to the technical field of environmental engineering, in particular to a method for preparing a magnetic adsorbent by using iron-manganese sludge of a water plant as a raw material.
Background
Iron and manganese ions exist in groundwater in many areas and need to be removed before groundwater is used, and a common method is to aerate mined groundwater to oxidize the iron ions and the manganese ions into particles and remove the particles through filtration, so that the aim of purifying the iron and manganese ions in the water is fulfilled. Aeration and filtration are commonly used processes in waterworks. After the water plant operates for a period of time, after excessive ferro-manganese particles are trapped in the filter tank, the water yield of the filter tank is reduced, and the particles trapped in a filter layer need to be removed by backwashing. During backwashing, ferro-manganese particles intercepted on the surface of the filter layer are peeled off and enter backwashing water, and after the backwashing water is stood still, the particles are gradually settled to the bottom to generate sludge containing ferro-manganese.
In practical engineering, the concentration of ferromanganese in groundwater is not a constant value. In the aeration oxidation stage, floccules or particles formed by iron and manganese can also adsorb substances in water, including metal ions, fine particles and the like. The filter material is also crushed during back washing, enters back washing water and is precipitated together with the ferro-manganese particles. Therefore, the iron manganese and impurity contents in the precipitate are not a stable value. In our earlier studies, iron sludge from the same water plant was analyzed and iron content was found to be a minimum of 14.3 wt.% and a maximum of 35.8 wt.%. Especially, the iron content difference of iron mud samples separated by one week is also up to 6 wt.%.
At present, the treatment measure of the iron mud in the water plant is to carry out the landfill after dehydration. The method for resource utilization of iron mud in literature reports relates to the following aspects. (1) Pretreating the iron-containing sludge by using acid, and then carrying out reactions such as coprecipitation, element separation, hydrothermal reaction or solvothermal reaction and the like; (2) mixing reducing materials such as pyrite and coke into the iron-containing sludge, or introducing reducing gas, and calcining the synthetic magnetic material or the refined iron ore at high temperature; (3) and adding a reducing agent into the iron mud by a solvothermal method to prepare the magnetic adsorbent. The process is similar to the hydrothermal reaction except that the water is replaced with an organic solvent; (4) the reports of hydrothermal reaction in the application of iron mud mostly focus on red mud treatment, relate to the aspects of element recovery, rare earth element loading preparation of catalysts and the like, and have fewer reports on the preparation of magnetic materials. Here, a few reports on the production of magnetic materials from red mud or iron-containing sludge are briefly introduced. Lingjun Ma and the like hydrothermally treat fly ash, red mud and steel slag, and react for 6 hours at 200 ℃ to prepare the magnetic zeolite.
Hydrothermal method for synthesizing Fe-containing3O4、Fe2O3The magnetic materials are usually chemically pure iron salts, such as ferric chloride, ferric nitrate, and ferric citrate. Dissolving iron salt in water to prepare homogeneous solution, and hydrothermal reaction to promote hydrolysis of iron ion, polycondensation to form nucleus and promote crystal nucleus growth to form magnetic Fe3O4Or gamma-Fe2O3. In the reaction, according to the iron content in the raw materials, the added coordination salt or auxiliary reagent is accurately metered to synthesize the magnetic materials with different shapes. Compared with homogeneous reaction, the iron-containing sludge is used for preparing magnetic materials on the principle that Fe-O-M (metal ions such as Al, Si, Mg and the like) bonds are broken to promote recrystallization of crystals to form the magnetic iron oxide.
Based on the currently reported hydrothermal method for preparing magnetic materials, if the content of iron salt in the raw materials is changed, experiments are required to determine appropriate reaction conditions (such as the addition amount of the oxidant or the reducing agent and the hydrothermal time). As previously noted, the iron and manganese content of iron sludge from waterworks is not a constant value, and varies with groundwater quality and operating process conditions. According to the existing hydrothermal reaction method, products with good magnetic response are prepared according to the molar ratio of ascorbic acid to iron of 1:1 and 2:1 for iron mud with the iron content of 16.6 wt.% and the manganese content of 6.1 wt.%, and the obtained products are weak in magnetism and do not migrate to a magnetic field in water when the conditions are applied to 5 batches of iron mud sampled later. In addition, only 1 sample of the iron sludge samples sampled in the other 3 waterworks showed a weak magnetic response. This indicates that after each backwashing of the water plant, the content of iron and manganese and the components of other impurities in the iron mud need to be detected again, and then a plurality of experiments are carried out to obtain a proper operation condition. The analysis of iron and manganese contents and other impurity components in the iron mud requires the use of various detection devices, including XRF, ICP-AES and the like. Simple analysis also requires on-site digestion followed by titration to calculate elemental content. After the steps are completed, batch hydrothermal experiments are carried out to obtain optimized operation conditions, such as the addition amount of the reducing agent, the reaction time, the content of the complex salt and the like.
Therefore, the optimization method obtained by experiments aiming at the components of the fixed raw materials in the existing hydrothermal technology is not suitable for the actual situation of the change of the components of the sludge in the water plant. The method provides a new problem for optimizing conditions such as reagent dosage, reaction time and the like in the concrete sludge treatment of a water plant by using a modern hydrothermal method.
Disclosure of Invention
The invention aims to provide a method for preparing a magnetic adsorbent by using waterworks ferro-manganese sludge as a raw material, which improves the magnetic response of the adsorbent by controlling the hydrothermal reaction time through online detection of the generation potential of carbonate ions, avoids the steps of detecting the components of the waterworks ferro-manganese sludge, optimizing experimental conditions for batch experiments aiming at the components of the ferro-manganese sludge and the like, and provides a method for practical application of the waterworks ferro-manganese sludge in preparation of the magnetic adsorbent so as to solve the problems in the background technology.
In order to achieve the purpose, the invention provides the following technical scheme:
a method for preparing a magnetic adsorbent by taking iron-manganese sludge of a water plant as a raw material comprises the following steps:
the method comprises the following steps: selecting the type of iron-manganese sludge
The iron sludge is sludge generated after the precipitation of the backwashing wastewater of the underground water plant, and contains iron-manganese minerals and impurities. The impurities are crushed filter materials, particles brought by underground water mining and a coagulant for strengthening the precipitation of the particles in the backwashing wastewater;
step two: conditions of hydrothermal reaction
Preparing a regulating solution with alkalinity of 2-4mol/L by using flake caustic soda or granular caustic soda; adding the regulating solution into the iron-manganese sludge according to the volume ratio of the regulating solution to the iron-manganese sludge of 0.5-2: 1; after being stirred uniformly, the mixture is transferred into a reaction kettle; adding 2-7.5g/L sodium ascorbate into the reaction kettle; sealing, starting the heating device, and heating to 140-.
Adding a sodium ascorbate solution with the concentration of 5-30% into the reaction kettle by using a high-pressure injection pump, wherein the adding speed is 2-50 mL/h;
step three: time control of hydrothermal reaction
The time control of the hydrothermal reaction is completed by a hydrothermal reaction system and an automatic control system;
step four: recovery of supernatant
After the reaction kettle is cooled to room temperature, magnetically separating and collecting bottom sediment; adding lime into residual alkali liquor in the reaction kettle, wherein the adding amount is 1-5 g/L; sealing the reaction kettle, starting a heating device, heating to 90-95 ℃, keeping the temperature for 1-2 hours, and cooling to room temperature; filtering with filter cloth, and reusing the filtrate for preparing regulating solution; the recycling of the regulating solution can reduce the alkali consumption and the water consumption, and the preparation cost of the magnetic adsorbent is saved 1/5;
step five: application conditions of magnetic adsorbent
Drying the precipitate obtained in the fourth step at 50 deg.C under vacuum degree of 0.04-0.08MPa for 24 hr. After drying, the magnetic adsorbent with good dispersibility is obtained.
Preferably, the hydrothermal reaction system in the third step comprises a liquid storage barrel, a high-pressure injection pump, a high-pressure one-way valve, a hydrothermal reaction kettle, a heating device, an automatic sampling device and a power supply controller, wherein the power supply controller is respectively connected with the heating device, the high-pressure injection pump and the automatic sampling device through power supply lines; the inlet of the high-pressure injection pump is connected with the bottom of the liquid storage barrel, the outlet of the high-pressure injection pump is connected with the high-pressure one-way valve, and the high-pressure one-way valve is connected with the dosing port of the hydrothermal reaction kettle; the automatic sampling device is connected with the hydrothermal reaction kettle.
Preferably, the automatic control system in step three comprises: the device comprises a cooling device, a diluting device, a sample injector, an ion chromatograph, a data collector, a process controller, a computer and a one-way valve; the inlet of the cooling device is connected with the automatic sampling device; the diluting device is connected with the cooling device through a one-way valve; the outlet of the cooling device is connected with the sample injector; the sample injector is connected with the ion chromatograph through a one-way valve; the redundant samples in the sample injector are discharged outside through a one-way valve; the ion chromatograph is connected with the data acquisition unit through a data line; the data acquisition unit is connected with a data signal input interface of the process controller through a data line; the process controller is respectively connected with the computer and the power supply controller through data lines, receives the detection value transmitted by the data acquisition unit, calculates the generation rate of carbonate ions according to the detection value and time through a logic program integrated in the process controller, transmits the real-time data of the generation rate of the carbonate ions to the computer through the data lines, and displays the data on a software interface of the computer; the control instruction sent by the computer is transmitted to the process controller, and the process controller controls the power supply controller through the output bus.
Preferably, step three further comprises the steps of:
the method comprises the following steps: using an automatic sampler, wherein the sampling time interval is 1-5min, and the sampling quantity is 0.1-5 mL; after the sample is treated by a cooling device, adding ultrapure water for diluting by 1-50 times;
step two: logic within the process controller integrates the carbonate ion concentration versus time relationship: r ═ C(x+1)-Cx)/(tx+1-tx) (ii) a Wherein r is carbonate ion generation potential in mg/L.h, C is carbonate ion concentration, x is the number of a detection sample, and t is sampling time. The sampler collects samples at the same time interval, and the process controller calculates a carbonate ion generation rate value according to the measured value and time of the samples and feeds back the value to the computer; the computer draws a curve of the generation rate of carbonate ions, and instructs the power supply controller to turn off the power supplies of the heating device, the high-pressure injection pump and the automatic sampling device according to an inflection point and a characteristic peak which appear after the generation rate of the carbonate ions in the curve is a negative value;
step three: the computer identifies the inflection point and the characteristic peak 2 hours after the reaction begins;
step four: the power supply is turned off after the inflection point appears, and the prepared sample has good magnetic response and contains low content of siderite and rhodochrosite;
step five: and after the characteristic peak appears, the power supply is turned off, the prepared sample has strong magnetic response, and the siderite and the rhodochrosite have high content.
Preferably, the application features in step five include:
(1) the magnetic adsorbent contains siderite and rhodochrosite, can rapidly reduce nitrite in water, and is characterized by comprising the following components in percentage by weight: the concentration of nitrite in water is 5-1000 mg/L; adding 0.3-80g/L magnetic adsorbent into water, stirring and mixing for 5-30min to remove nitrite in water; after the reaction is finished, collecting the magnetic adsorbent through magnetic separation;
(2) the method is characterized in that a magnetic adsorbent is added into the wastewater containing heavy metal ions, and the heavy metal ions in the wastewater can be removed within 15 minutes through ion exchange, and the application characteristics comprise: the smelting wastewater contains 95mg/L Cu2+,35mg/LZn2+,5.4mg/LPb2+And 3.7mg/L Cd2+The pH was 0.8. Adding 12.5g/L magnetic adsorbent directly into the smelting wastewater, mechanically stirring and mixing for 15 minutes, recovering the adsorbent through magnetic separation, and recovering Cu in water2+，Zn2+,Pb2+And Cd2+The removal rate of ions exceeds 99 percent, and the pH value of effluent is 6.1. The recovered adsorbent may be regenerated. The smelting wastewater is treated by using the adsorbent, and the cost of water treatment per ton is 1/8 of granular activated carbon;
(3) siderite and rhodochrosite in the magnetic adsorbent can react with persulfate to generate active free radicals to oxidize organic matters in water, and the application characteristics of the siderite and the rhodochrosite comprise: adding 0.02-1g/L of magnetic adsorbent and 0.01-0.5g/L of persulfate into the organic wastewater, stirring and mixing for 30-120min, and removing 90% of organic matters in the water; after the reaction is completed, the magnetic adsorbent can be recovered by magnetic separation.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention discloses a method for preparing a magnetic adsorbent by using waterworks ferro-manganese sludge as a raw material, which provides a method for determining the end point of hydrothermal reaction time according to the inflection point or characteristic peak of carbonate ion concentration change, thereby realizing accurate control of the hydrothermal reaction. In the prior art, the content of iron in the iron mud needs to be detected, the amount of ascorbic acid added is determined according to the content of iron, and the reaction time is optimized through experiments. Because the iron and manganese content in the iron mud of the water plant changes, the reaction time needs to be determined by carrying out experiments again, the time consumption is long, the steps are complicated, and the workload is large.
2. The method for preparing the magnetic adsorbent by using the waterworks ferro-manganese sludge as the raw material can adjust the content of siderite and rhodochrosite in the magnetic adsorbent according to inflection points and characteristic peaks.
3. According to the method for preparing the magnetic adsorbent by using the iron-manganese sludge of the water plant as the raw material, after the hydrothermal reaction is finished, the alkalinity of the supernatant is high, and the supernatant can be reused for preparing the regulating solution after dealumination treatment. In the related methods reported, the recycling of the supernatant is not taken into account.
Drawings
FIG. 1 is a block diagram of the system of the present invention;
FIG. 2 is a schematic diagram of detecting carbonate ion generation potential according to the present invention;
FIG. 3 shows the magnetic adsorbent of the present invention for removing Cu and Zn from water;
FIG. 4 shows the removal of nitrite and organic compounds from water by the magnetic adsorbent of the present invention.
In the figure: 1. a liquid storage barrel; 2. a high pressure syringe pump; 3. a high pressure check valve; 4. a hydrothermal reaction kettle; 5. a heating device; 6. an automatic sampling device; 7. a cooling device; 8. a dilution device; 9. a sample injector; 10. an ion chromatograph; 11. a data acquisition unit; 12. a process controller; 13. a computer; 14. a power supply controller 14; 15. a one-way valve.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1-4, a method for preparing a magnetic adsorbent from iron-manganese sludge of a water plant comprises the following steps:
the method comprises the following steps: selecting the type of iron-manganese sludge
Taking iron-manganese sludge generated after coagulation of the backwashing wastewater of the underground water plant, standing for 24h, and taking bottom sludge for later use, wherein the iron sludge is sludge generated after precipitation of the backwashing wastewater of the underground water plant and contains iron-manganese minerals and impurities. The impurities are crushed filter materials, particles brought by underground water mining and a coagulant for strengthening the precipitation of the particles in the backwashing wastewater; the iron-manganese sludge in the water plant is influenced by water quality, coagulant addition and operation conditions, the change range of the iron content in the sediment is 4.7-35.8 wt.%, and the change range of the manganese is 2.48-12.2 wt.%;
step two: conditions of hydrothermal reaction
Preparing 2mol/L sodium hydroxide solution by using caustic soda flakes; 1L of bottom sludge and 1L of sodium hydroxide solution are poured into the reaction kettle, and the mixture is continuously stirred for 5min at 200 rpm; adding 5.4g/L sodium ascorbate into a reaction kettle; sealing the reaction kettle, starting a heating device, and heating to 180 ℃;
starting a high-pressure injection pump, adding a sodium ascorbate solution with the concentration of 20% into the reaction kettle, wherein the adding speed is 10 mL/h;
step three: time control of hydrothermal reaction
The time control of the hydrothermal reaction is completed by a hydrothermal reaction system and an automatic control system;
the hydrothermal reaction system comprises a liquid storage barrel 1, a high-pressure injection pump 2, a high-pressure one-way valve 3, a hydrothermal reaction kettle 4, a heating device 5, an automatic sampling device 6 and a power supply controller 14, wherein the power supply controller 14 is respectively connected with the heating device 5, the high-pressure injection pump 2 and the automatic sampling device 6 through power supply wires; an inlet of the high-pressure injection pump 2 is connected with the bottom of the liquid storage barrel 1, an outlet of the high-pressure injection pump 2 is connected with the high-pressure one-way valve 3, and the high-pressure one-way valve 3 is connected with a dosing port of the hydrothermal reaction kettle 4; the automatic sampling device 6 is connected with the hydrothermal reaction kettle 4.
The automatic control system includes: a cooling device 7, a diluting device 8, an injector 9, an ion chromatograph 10, a data collector 11, a process controller 12, a computer 13 and a one-way valve 15; the inlet of the cooling device 7 is connected with the automatic sampling device 6; the dilution device 8 is connected with the cooling device 7 through a one-way valve 15; the outlet of the cooling device 7 is connected with the sample injector 9; the sample injector 9 is connected with the ion chromatograph 10 through a one-way valve 15; the redundant sample in the sample injector 9 is discharged outside through the one-way valve 15; the ion chromatograph 10 is connected with a data acquisition unit 11 through a data line; the data acquisition unit 11 is connected with a data signal input interface of the process controller 12 through a data line; the process controller 12 is respectively connected with the computer 13 and the power controller 14 through data lines, the process controller 12 receives the detection value transmitted by the data collector 11, calculates the generation rate of carbonate ions according to the detection value and time through a logic program integrated in the process controller 12, transmits the real-time data of the generation rate of the carbonate ions to the computer 13 through the data lines, and displays the data on a software interface of the computer 13; a control instruction sent by the computer 13 is transmitted to the process controller 12, and the process controller 12 controls the power controller 14 through an output bus;
using an automatic sampler, wherein the sampling time interval is 5min, and the sampling quantity is 1 mL; after the sample is treated to room temperature by a cooling device, adding ultrapure water for diluting by 5 times by a diluting device; 200 mu L of sample is collected by a sample injector and sent to an ion chromatograph, and the concentration of carbonate ions is detected; using an automatic sampler, wherein the sampling time interval is 5min, and the sampling quantity is 1 mL; after the sample is treated to room temperature by a cooling device, adding ultrapure water for diluting by 5 times by a diluting device; 200 mu L of sample collected by the sample injector is sent to an ion chromatograph, and the concentration of carbonate ions is detected.
The data collector collects the carbonate ion concentration signal and transmits the signal to the process controller. The process controller calculates the carbonate generation potential by the following formula:
r＝(Cx+1-Cx)×60/5
wherein r is carbonate ion generation potential, C is carbonate ion concentration, and x is sample number.
The process controller feeds back the signal of the generated potential to the computer and draws a curve of the generated potential of the carbonate ions. When the carbonate ion generation potential is reduced from a positive value and approaches 0, it indicates that the dissolved oxygen in the reaction kettle is exhausted.
When the carbonate ion generation potential becomes negative, the state is maintained for 20 minutes (see figure 2), the computer sends out an instruction through the process controller to close the power supply controller, so that the heating device, the dosing pump and the sampling device are stopped, the prepared magnetic adsorbent is low in rhodochrosite and siderite, and the XRD spectrogram is shown in figure 3.
When the generation potential of the carbonate ions becomes a negative value, the computer detects that the curve of the generation potential has a peak value (see attached figure 2), namely the generation potential begins to gradually increase, after the state is maintained for 20 minutes, the computer sends an instruction to close the power supply controller through the process controller, the content of rhodochrosite and siderite in the prepared magnetic adsorbent is high, and the XRD spectrogram of the magnetic adsorbent is shown in attached figure 4;
step four: recovery of supernatant
After the reaction kettle is cooled to room temperature, magnetically separating and collecting bottom sediment; adding lime into the residual alkali liquor in the reaction kettle at a dosage of 1.5 g/L; sealing the reaction kettle, starting a heating device, heating to 90 ℃, keeping the temperature for 1h, and cooling to room temperature; after filtering by using filter cloth, the removal rate of the metaaluminate in the filtrate can reach 65 percent, and the metaaluminate can be reused for preparing the regulating solution;
step five: application conditions of magnetic adsorbent
The magnetically separated precipitate was dried at 50 ℃ for 24h under a vacuum of 0.06MPa for future use.
(1) The magnetic adsorbent containing siderite and rhodochrosite can be applied to the treatment of wastewater containing nitrite, and is characterized in that siderite and rhodochrosite in the magnetic adsorbent reduce nitrite into nitrous oxide or nitrogen, divalent iron and divalent manganese are oxidized into high valence, and more hydroxyl functional groups generated on the surface are used as active sites to adsorb organic pollutants in water. Application example: the nitrite content in the machining wastewater is 412.5mg/L, the COD content is 1378mg/L and the pH value is 8.7. Adding 45g/L of magnetic adsorbent containing siderite and rhodochrosite into the wastewater, and stirring for 30min, wherein the nitrite removal rate reaches 91%, and the COD removal rate reaches 47%. After adsorption is finished, the adsorbent can be quickly separated from the wastewater by an external magnetic field.
(2) And adding a magnetic adsorbent into the wastewater containing the heavy metal ions, and removing the heavy metal ions in the water within 15 minutes through ion exchange. Application example: the smelting wastewater contains 95mg/L Cu2+,35mg/LZn2+,5.4mg/L Pb2+And 3.7mg/L Cd2+The pH was 0.8. Adding 12.5g/L magnetic adsorbent directly into the smelting wastewater, mechanically stirring and mixing for 15 minutes, recovering the adsorbent through magnetic separation, and recovering Cu in water2+，Zn2+,Pb2+And Cd2+The removal rate of ions exceeds 99 percent, and the pH value of effluent is 6.1. The recovered adsorbent can be regenerated by: dispersing the magnetically separated adsorbent in 3M NaCl solution, regulating pH to 2.5, stirring for 2 hr, and magnetically separating. The maximum adsorption capacity of the regenerated magnetic adsorbent can reach 82% of the initial level, and the effect is not obviously reduced after the magnetic adsorbent is repeatedly used for 4 times. The cost of treating the smelting wastewater by using the adsorbent is 1/8 of granular activated carbon per ton.
(3) The magnetic adsorbent containing siderite and rhodochrosite can react with persulfate to generate active free radical to oxidize organic matters in water. Application example: the COD of the domestic sewage is 397.2 mg/L. 0.8g/L of magnetic adsorbent and 0.5g/L of persulfate are added into the sewage, the mixture is stirred and mixed for 90min, and the removal rate of COD reaches 91.4%. After the reaction is completed, the adsorbent in the water can be rapidly recovered through magnetic separation.
In summary, the method for preparing the magnetic adsorbent by using the iron and manganese sludge of the water plant as the raw material provided by the invention can flexibly control the reaction time and adjust the dosage of the reducing agent by measuring the generation rate of the carbonate concentration, can directly obtain the magnetic material with good magnetic response and high adsorption performance under the conditions of not detecting the element composition in the iron sludge and not performing batch hydrothermal experiments, improves the magnetic response of the adsorbent by controlling the hydrothermal reaction time by detecting the generation potential of the carbonate ions on line, avoids the steps of detecting the iron and manganese sludge components of the water plant, optimizing experimental conditions for batch experiments aiming at the iron and manganese sludge components, and the like, and provides a method for the practical application of preparing the magnetic adsorbent by using the iron and manganese sludge of the water plant.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.
Claims (3)
1. A method for preparing a magnetic adsorbent by taking iron-manganese sludge of a water plant as a raw material is characterized by comprising the following steps: the method comprises the following steps:
the method comprises the following steps: selecting the type of iron-manganese sludge
The ferro-manganese sludge is sludge generated after the precipitation of the backwashing wastewater of the underground water plant and contains ferro-manganese minerals and impurities, wherein the impurities are crushed filter materials, particles brought by underground water mining and coagulants for strengthening the precipitation of the particles in the backwashing wastewater;
step two: conditions of hydrothermal reaction
Preparing a regulating solution with the concentration of 2-4mol/L by using flake caustic soda or granular caustic soda; adding the regulating solution into the iron-manganese sludge according to the volume ratio of the regulating solution to the iron-manganese sludge of 0.5-2: 1; after being stirred uniformly, the mixture is transferred into a reaction kettle; adding 5-30% sodium ascorbate solution into a reaction kettle by using a high-pressure injection pump, wherein the adding rate is 2-50mL/h, and the adding amount is 2-7.5 g/L; sealing, starting a heating device, and heating to 140-270 ℃;
step three: time control of hydrothermal reaction
The time control of the hydrothermal reaction is completed by a hydrothermal reaction system and an automatic control system;
step four: recovery of supernatant
After the reaction kettle is cooled to room temperature, magnetically separating and collecting bottom sediment; adding lime into residual alkali liquor in the reaction kettle, wherein the adding amount is 1-5 g/L; sealing the reaction kettle, starting a heating device, heating to 90-95 ℃, keeping the temperature for 1-2 hours, and cooling to room temperature; filtering with filter cloth, and reusing the filtrate for preparing regulating solution; the recycling of the regulating solution can reduce the alkali consumption and the water consumption, and the preparation cost of the magnetic adsorbent is saved 1/5;
step five: application conditions of magnetic adsorbent
Drying the precipitate obtained by magnetic separation in the fourth step at 50 ℃ for 24h under the vacuum degree of 0.04-0.08MPa, and drying to obtain a magnetic adsorbent with good dispersibility, wherein the hydrothermal reaction system in the third step comprises a liquid storage barrel (1), a high-pressure injection pump (2), a high-pressure one-way valve (3), a hydrothermal reaction kettle (4), a heating device (5), an automatic sampling device (6) and a power supply controller (14), and the power supply controller (14) is respectively connected with the heating device (5), the high-pressure injection pump (2) and the automatic sampling device (6) through power supply wires; an inlet of the high-pressure injection pump (2) is connected with the bottom of the liquid storage barrel (1), an outlet of the high-pressure injection pump (2) is connected with the high-pressure one-way valve (3), and the high-pressure one-way valve (3) is connected with a dosing port of the hydrothermal reaction kettle (4); the automatic sampling device (6) is connected with the hydrothermal reaction kettle (4).
2. The method for preparing the magnetic adsorbent by using the iron-manganese sludge of the water plant as the raw material according to claim 1, wherein the method comprises the following steps: the automatic control system in step three comprises: the device comprises a cooling device (7), a diluting device (8), a sample injector (9), an ion chromatograph (10), a data collector (11), a process controller (12), a computer (13) and a one-way valve (15); the inlet of the cooling device (7) is connected with the automatic sampling device (6); the diluting device (8) is connected with the cooling device (7) through a one-way valve (15); the outlet of the cooling device (7) is connected with the sample injector (9); the sample injector (9) is connected with the ion chromatograph (10) through a one-way valve (15); the redundant sample in the sample injector (9) is discharged outside through a one-way valve (15); the ion chromatograph (10) is connected with the data acquisition unit (11) through a data line; the data acquisition unit (11) is connected with a data signal input interface of the process controller (12) through a data line; the process controller (12) is respectively connected with the computer (13) and the power supply controller (14) through data lines, the process controller (12) receives the detection value transmitted by the data acquisition unit (11), calculates the generation rate of carbonate ions according to the detection value and time through a logic program integrated in the process controller (12), transmits the data of the real-time generation rate of the carbonate ions to the computer (13) through the data lines, and displays the data on a software interface of the computer (13); the control command sent by the computer (13) is transmitted to the process controller (12), and the process controller (12) controls the power supply controller (14) through the output bus.
3. The method for preparing the magnetic adsorbent by using the iron-manganese sludge of the water plant as the raw material according to claim 1, wherein the method comprises the following steps: the third step specifically comprises the following steps:
the method comprises the following steps: using an automatic sampler, wherein the sampling time interval is 1-5min, and the sampling quantity is 0.1-5 mL; after the sample is treated by a cooling device, adding ultrapure water for diluting by 1-50 times;
step two: logic within the process controller integrates the carbonate ion concentration versus time relationship: r ═ Cx+1-Cx)/(tx+1-tx) (ii) a Wherein r is carbonate ion generation potential, the unit is mg/L.h, C is carbonate ion concentration, x is the number of a detection sample, and t is sampling time; the sampler collects samples at the same time interval, and the process controller calculates a carbonate ion generation rate value according to the measured value and time of the samples and feeds back the value to the computer; computer plotting carbonate generation rate from the plotThe inflection point and the characteristic peak which appear after the generation rate of the carbonate ions in the line is a negative value indicate the power controller to turn off the power supplies of the heating device, the high-pressure injection pump and the automatic sampling device;
step three: the computer identifies the inflection point and the characteristic peak 2 hours after the reaction begins;
step four: the power supply is turned off after the inflection point appears, and the prepared sample has good magnetic response and contains low content of siderite and rhodochrosite;
step five: and after the characteristic peak appears, the power supply is turned off, the prepared sample has strong magnetic response, and the siderite and the rhodochrosite have high content.
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| CN111003879B (en) * | 2019-12-26 | 2021-10-26 | 东北师范大学 | Method for synthesizing coagulant containing erdite at normal temperature by using waste mud containing iron and treating wastewater by using coagulant |
| CN111450799B (en) * | 2020-03-24 | 2022-04-01 | 天津科技大学 | Preparation method of magnetic activated carbon based on black liquor lignin and Fenton sludge |
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