CN110876918B - Preparation method of efficient nitrate radical treating agent - Google Patents

Preparation method of efficient nitrate radical treating agent Download PDF

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CN110876918B
CN110876918B CN201811035482.9A CN201811035482A CN110876918B CN 110876918 B CN110876918 B CN 110876918B CN 201811035482 A CN201811035482 A CN 201811035482A CN 110876918 B CN110876918 B CN 110876918B
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montmorillonite
nitrate
hydrotalcite
treating agent
nitrate radical
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CN110876918A (en
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李波
刘婷婷
李茂双
潘咸峰
黄斌
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China Petroleum and Chemical Corp
Qilu Petrochemical Co of Sinopec
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Qilu Petrochemical Co of Sinopec
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/10—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate
    • B01J20/16—Alumino-silicates
    • B01J20/165—Natural alumino-silicates, e.g. zeolites
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/28—Treatment of water, waste water, or sewage by sorption
    • C02F1/281—Treatment of water, waste water, or sewage by sorption using inorganic sorbents
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/16—Nitrogen compounds, e.g. ammonia
    • C02F2101/163—Nitrates
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W10/00—Technologies for wastewater treatment
    • Y02W10/10—Biological treatment of water, waste water, or sewage

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  • Inorganic Chemistry (AREA)
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  • Chemical Kinetics & Catalysis (AREA)
  • Water Treatment By Sorption (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)

Abstract

The invention belongs to the field of sewage treatment, and particularly relates to a preparation method of an efficient nitrate radical treating agent. The preparation method of the high-efficiency nitrate radical treating agent comprises the steps of respectively preparing hydrotalcite with adjustable and controllable interlayer structures and polypyrrole-modified montmorillonite, firstly carrying out delaminating separation on the hydrotalcite to form a dispersed lamellar structure, changing the surface electrical property of the material by utilizing the adjustable and variable characteristics of the type and the quantity of cations of a hydrotalcite polar plate, forming steric hindrance by utilizing modification of the polypyrrole of the montmorillonite, and finally carrying out composite bonding and intercalation on the hydrotalcite and the montmorillonite to form a layered structure composite material with certain steric hindrance, wherein the material is applied to adsorbing nitrate radicals in high-salt wastewater (especially high-salt wastewater with high sulfate radical content), has good adsorption selectivity and adsorption capacity, and the removal rate of the nitrate radicals in the wastewater is more than or equal to 65%.

Description

Preparation method of efficient nitrate radical treating agent
Technical Field
The invention belongs to the field of sewage treatment, and particularly relates to a preparation method of an efficient nitrate radical treating agent.
Background
After the nitrate is accumulated in the human body, the nitrate is subjected to nitrate reductaseNitrite is generated by action, and can be converted into nitrosamine and nitrosophthalide which have carcinogenesis, teratogenesis and mutagenesis under the action of various nitrogenous organic compounds such as amine, urea, cyanamide and the like, so as to induce human body to generate various tumors, such as intestinal tract, nervous system, brain, skin, skeleton and other tumor diseases. Nitrate is also easy to cause goiter, inhibits the thyroid from taking in inorganic iodine, and even in a water body with high iodine content, if the content of nitrate in water is high, endemic goiter is easy to cause. Nitrite also reacts with hemoglobin in the blood to form methemoglobin, which affects the oxygen transport in the blood and makes the cell tissue anoxic, even leading to respiratory cycle failure in severe cases. Compared with adults, infants are sensitive to the potential toxicity of nitrate, and when the content of the nitrate in drinking water reaches 90-140mg/L, the infants are easy to suffer from methemoglobinemia, the skin of the infants turns into blue gray, which is commonly called as 'blue infant disease', and serious people can cause suffocation. Since nitrate pollution can be harmful to human health, various countries around the world set standards for nitrate content in drinking water, where the world health organization stipulates Nitrate (NO) 3 -N) not more than 10mg/L, Nitrite (NO) 2 -N) not more than 0.91mg/L, the U.S. EPA specified maximum limit being (NO) 3 -N)10mg/L，(NO 2 -N)1mg/L, and the content of nitrate nitrogen in water is less than or equal to 10mg/L as specified by the water quality standard of domestic drinking water (GBS749-2006) in China.
The pollution of nitrate has received extensive attention, and the research on the nitrate control technology is increasing at home and abroad. At present, the control technology of nitrate mainly comprises a biological method, a physical chemical method and a chemical reduction method. The biological method is a method for gradually converting nitrogen-containing substances in sewage into nitrogen under the action of microorganisms. The physical and chemical methods mainly include a membrane separation method, an ion exchange method and an adsorption method. However, these methods generally have high running costs and complicated regeneration processes. The chemical reduction method is a very effective method for degrading nitrate, but how to reduce harmful substances, namely ammonia nitrogen and nitrite in a reduction product and improve the selectivity of nitrogen of the reduction product is a research hotspot at present. Although the catalytic hydrogenation reduction method can effectively improve the selectivity of nitrogen in the reduction product, the method uses hydrogen as a reducing agent, has certain potential safety hazard, and has low solubility of hydrogen in water and low utilization rate.
Patent CN 107694541A discloses a preparation and application of a nitrate treating agent, which takes cotton as a template, adopts a coprecipitation method to synthesize zinc-titanium-iron ternary hydrotalcite-like compound with biological morphology, and obtains the nitrate treating agent by roasting in a muffle furnace. The invention also provides application of the nitrate treating agent prepared by the method in nitrate wastewater treatment. The nitrate treating agent prepared by the method has good adsorption effect on nitrate, is convenient to separate, has simple and easy regeneration method, and has wide application prospect in the field of nitrate wastewater treatment. But the treatment agent has better effect when being applied to the treatment of the conventional nitrate-containing wastewater, and does not relate to the absorption of nitrate in high-salinity wastewater. The salt content in the high-salt wastewater severely limits the adsorption effect of the adsorbent, so that the adsorbent needs to have certain adsorption selectivity in the process of adsorbing nitrate by the high-salt wastewater.
In the literature, "research on adsorption and degradation of nitrate ions by modified montmorillonite", authors provide that modified montmorillonite is obtained by exchanging interlayer cations of montmorillonite with polydiallyldimethylammonium chloride, and the structural ferric ions of montmorillonite are chemically reduced to the structural ferrous ions. The capacity of unmodified montmorillonite in different oxidation states for adsorbing and degrading nitrate ions is measured; the level of nitrate ion adsorption by the oxidized modified montmorillonite under different charging conditions; the ability of the reduced modified montmorillonite to degrade nitrate ions. The experimental results show that: the oxidized unmodified montmorillonite can hardly adsorb and reduce and degrade nitrate ions; the reduced state unmodified montmorillonite can absorb nitrate ions of about 0.0054mmol/g, and generates a very small amount of low-valence nitro products; the oxidation state modified montmorillonite can adsorb nitrate ions of 0.23mmol/g, and the adsorption capacity of the oxidation state modified montmorillonite is increased along with the increase of the concentration of interlayer polymerization cations. The modified clay mineral is proved to be capable of strongly adsorbing nitrate ions, and a potential research direction is provided for the treatment of nitrate ion pollution. The article also does not relate to the treatment of waste water in which sulfate ions are present in the waste water in competition for adsorption with nitrate ions.
At present, the adsorbent is mostly applied to treating conventional wastewater containing nitrate ions, and the salt content in the wastewater is low. However, when the adsorbent is applied to the treatment of high-salinity wastewater, other anions in the wastewater rapidly occupy the adsorption sites on the surface of the adsorbent due to the competitive adsorption effect, so that the adsorption effect of nitrate is reduced.
Disclosure of Invention
The invention aims to provide a preparation method of an efficient nitrate radical treating agent, the prepared treating agent is applied to adsorbing high-salt wastewater, particularly high-salt wastewater with high sulfate radical content, the nitrate radical adsorption selectivity and the adsorption capacity have good effects, and the removal rate of nitrate radicals in the wastewater is more than or equal to 65%.
The preparation method of the high-efficiency nitrate radical treating agent comprises the following steps:
stage one, preparing magnesium-iron hydrotalcite:
(1) preparation of Mg (NO) 3 ) 2 ·6H 2 O and Fe (NO) 3 ) 3 ·9H 2 Mixed salt solution A of O, NaOH and Na 2 CO 3 The mixed solution B of (1);
(2) adding deionized water into a reactor, dropwise adding the mixed salt solution A and the mixed solution B into the reactor, stirring simultaneously, and controlling the pH value of the mixed stirring liquid in the reactor to be 9-10;
(3) after the dropwise addition is finished, the slurry is subjected to heat preservation and stirring at 60 ℃, aged for 12 hours, the formed hydrotalcite is filtered and washed, and a filter cake is transferred to a crucible and dried for later use;
stage two, hydrotalcite stripping:
(4) adding the hydrotalcite prepared in the step (3) into N, N-dimethylformamide, carrying out ultrasonic treatment for 24 hours, then carrying out centrifugal separation, distilling to remove the N, N-dimethylformamide, washing with absolute ethyl alcohol, then putting into an oven for drying at 120 ℃, and grinding to obtain hydrotalcite solid powder after lamella stripping;
and step three, modifying the montmorillonite polypyrrole:
(5) crushing raw montmorillonite soil to be less than 50 meshes, adding the crushed raw montmorillonite soil into deionized water, stirring for 30-60 minutes, standing, removing montmorillonite slurry on the upper layer, and removing sand and stones on the lower layer; adjusting the pH value of the montmorillonite slurry to acidity, then heating and flocculating for 10-15 minutes, standing at room temperature, centrifugally separating, drying, and grinding to obtain montmorillonite fine soil;
(6) adding the refined montmorillonite soil into deionized water, violently stirring for 60-90 min, and adding FeCl with the same mass as the refined montmorillonite soil at a temperature of 25-35 DEG C 3 Then adding pyrrole, reacting for 3-4 h at 30 ℃, respectively centrifugally washing for 3-4 times by using water and acetone to obtain modified montmorillonite, and drying for later use;
stage four, intercalation compounding:
(7) and (3) adding the hydrotalcite solid powder obtained after the lamella stripping in the step (4) and the modified montmorillonite obtained in the step (6) into deionized water, shearing for 60-90 min by using a high-shear disperser, centrifugally washing for 3 times by using the deionized water, drying in a forced air drying oven at 110 ℃, and roasting a dried sample at 250-300 ℃ for 4h to obtain the nitrate radical treating agent.
Wherein:
in the step (1), in the mixed salt solution A, Mg 2+ The mass concentration of the substance is 0.6-0.8 mol/L, Fe 3+ The mass concentration of the substances is 0.15-0.2 mol/L; in the mixed solution B, Na 2 CO 3 The amount concentration of the substance is 0.3-0.4 mol/L, and the amount concentration of the NaOH substance is 1.5-2 mol/L.
In the step (2), the dropping speed is 600-800ml/h, and the volume ratio of the deionized water to the mixed salt solution A to the mixed solution B is 2:1: 1-2.5: 1: 1.
in the step (3), the drying temperature is 105 ℃, and the drying time is 12 hours.
In the step (4), the mass ratio of the hydrotalcite to the N, N-dimethylformamide is 1: 10-1: 20.
in the step (5), the mass ratio of the montmorillonite raw soil to the deionized water is 0.05-0.2: 1.
in the step (5), the granularity of the montmorillonite fine soil is less than 200 meshes.
In the step (6), the mass ratio of the montmorillonite refined soil to the deionized water is 0.05-0.2: 1.
in the step (6), the mass ratio of the pyrrole to the montmorillonite fine soil is 0.06-0.25: 1.
in the step (7), the mass ratio of the hydrotalcite solid powder subjected to lamella stripping to the modified montmorillonite is 0.5: 1-3: 1.
preferably, the preparation method of the high-efficiency nitrate radical treating agent specifically comprises the following steps:
stage one, preparing magnesium-iron hydrotalcite:
(1) preparation of Mg (NO) 3 ) 2 ·6H 2 O and Fe (NO) 3 ) 3 ·9H 2 Mixed salt solution A of O, solution Mg 2+ The mass concentration of the substance is 0.6-0.8 mol/L, Fe 3+ The mass concentration of the substances is 0.15-0.2 mol/L; preparing NaOH and Na 2 CO 3 Mixed solution B of (1), Na in solution 2 CO 3 The amount concentration of the substance is 0.3-0.4 mol/L, and the amount concentration of the NaOH substance is 1.5-2 mol/L. And (3) preparing the mixed salt solution A and the mixed salt solution B for later use according to the volume ratio of 1: 1.
(2) Adding a certain volume of deionized water into a reactor, dropwise adding the mixed salt solution A and the mixed solution B into the reactor, stirring vigorously, and controlling the pH value of the mixed stirring liquid in the reactor to be 9-10. Wherein the dropping rate is 600-800ml/h, and the volume ratio of the deionized water to the solution A and the solution B is 2:1: 1-2.5: 1:1
(3) After titration, the slurry is stirred at the temperature of 60 ℃ and aged for 12 h. Filtering the formed hydrotalcite after aging, washing and filtering repeatedly for three times, transferring a filter cake into a crucible, drying for 12 hours in a drying oven at 105 ℃, and placing the product into a dryer for later use.
Stage two, hydrotalcite stripping:
(4) and (3) adding the hydrotalcite prepared in the step (3) into N, N-Dimethylformamide (DMF), wherein the mass ratio of the hydrotalcite to the DMF is 1: 10-1: 20, performing ultrasonic treatment for 24 hours, performing centrifugal separation, distilling to remove the DMF, washing with absolute ethyl alcohol, drying in an oven at 120 ℃, and grinding to obtain the hydrotalcite solid powder after lamella peeling.
And step three, modifying the montmorillonite polypyrrole:
(4) the method comprises the steps of crushing raw montmorillonite to be less than 50 meshes, weighing a certain mass of crushed montmorillonite, adding the montmorillonite into a certain volume of deionized water, stirring the mixture for 30-60 minutes by using a stirrer, standing, removing montmorillonite slurry on the upper layer, and discarding sand and stones on the lower layer. And adjusting the pH value of the montmorillonite slurry on the upper layer to be acidic, then heating and flocculating for 10-15 minutes on an electric furnace, standing for a certain time at room temperature, centrifugally separating to remove partial water and salt, drying, and grinding to obtain the montmorillonite fine soil with a certain particle size.
(5) Adding the purified montmorillonite fine soil into deionized water according to the mass ratio of 0.05-0.2, mechanically and violently stirring for 60-90 min, and slowly adding FeCl with the same mass as the montmorillonite 3 And then adding pyrrole, wherein the mass ratio of the pyrrole to the montmorillonite is 0.06-0.25, reacting for 3-4 h at 30 ℃, respectively centrifugally washing for 3-4 times by using water and acetone, and drying for later use.
And a fourth stage: intercalation compounding
(7) And (3) adding the hydrotalcite solid powder obtained after the lamella stripping in the step (4) and the modified montmorillonite obtained in the step (6) into deionized water according to the mass ratio of 0.5: 1-3: 1, shearing for 60-90 min by using a high-shear disperser, centrifugally washing for 3 times by using the deionized water, drying at 110 ℃ in a blast drying oven, and roasting a dried sample at 250-300 ℃ for 4 hours to obtain the nitrate radical treating agent.
The desulfurization and denitrification wastewater of an oil refinery is used as target water quality, the wastewater is high-salinity wastewater, the content of nitrate ions in the wastewater is 300-plus-300 ppm, the content of sulfate ions in the wastewater is 3000ppm, the conventional adsorbent is adopted, the adsorption effect is poor, and the removal rate of nitrate ions in the wastewater is more than or equal to 65 percent when the treating agent provided by the invention is used for treating the wastewater.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention respectively prepares hydrotalcite with adjustable and controllable interlayer structure and polypyrrole modified montmorillonite, firstly peels and separates the hydrotalcite to form a dispersed lamellar structure, utilizes the adjustable and variable characteristics of the type and the quantity of cations of a hydrotalcite polar plate to change the surface electrical property of the material, utilizes the polypyrrole modification of the montmorillonite to form steric hindrance, and finally carries out composite bonding and intercalation on the hydrotalcite and the montmorillonite to form a lamellar structure composite material with certain steric hindrance.
2. The treating agent prepared by the invention is applied to the process of adsorbing nitrate radical in high-salt wastewater, can be regenerated and reused through an adsorbent regeneration tower at 220 ℃ after the treating agent is saturated in adsorption, and is applied to the process of adsorbing nitrate radical in high-salt wastewater after the regeneration is finished, so that the removal rate of nitrate radical is still stably more than or equal to 65%.
Detailed Description
The present invention is further described below with reference to examples.
The starting materials used in the examples are all commercially available except where otherwise indicated.
Example 1
The preparation method of the high-efficiency nitrate radical treating agent comprises the following steps:
(1) formulation 2LMg (NO) 3 ) 2 ·6H 2 O and Fe (NO) 3 ) 3 ·9H 2 Mixed salt solution A of O, Mg in solution 2+ The mass concentration of the substance is 0.6mol/L, Fe 3+ The mass concentration of the substance is 0.15 mol/L; preparation of 2L NaOH and Na 2 CO 3 Mixed solution B, Na of 2 CO 3 The mass concentration of the substance is 0.3mol/L, and the mass concentration of the NaOH substance is 1.5 mol/L. After 4L of deionized water is added into a 10L reactor, the mixed salt solution A and the mixed solution B are dropwise added into the reactor at the dropping speed of 800ml/h while vigorously stirring, and the pH value of the mixed stirring liquid in the reactor is controlled to be 9. After titration, the slurry is stirred at the temperature of 60 ℃ and aged for 12 h. And after aging, filtering the formed hydrotalcite, washing and filtering repeatedly for three times, transferring a filter cake into a crucible, drying for 12 hours in a drying oven at 105 ℃, and placing the product into a dryer for later use. Adding the hydrotalcite to be used into DMF according to the mass ratio of 1:10 of the hydrotalcite to the DMF, carrying out ultrasonic treatment for 24 hours, and then carrying out centrifugal separationAnd (3) after DMF is removed by distillation, washing the hydrotalcite with absolute ethyl alcohol, then putting the hydrotalcite into an oven for drying at 120 ℃, and grinding to obtain the hydrotalcite solid powder after lamella stripping.
(2) Weighing 1kg of raw montmorillonite, crushing to less than 50 meshes, weighing 0.5kg of the crushed raw montmorillonite, adding into a plastic barrel, adding 10L of deionized water, stirring for 30 minutes by using a stirrer, standing, removing montmorillonite slurry on the upper layer, and removing sand and stones on the lower layer. Adjusting the pH value of the montmorillonite slurry on the upper layer to acidity, then heating and flocculating for 10 minutes on an electric furnace, standing for a certain time at room temperature, centrifugally separating to remove partial water and salt, drying and grinding. Adding ground montmorillonite fine soil 100g into 2L deionized water, mechanically stirring for 60min, controlling temperature at 25 deg.C, and adding FeCl 3 100g, then adding 12.5ml of pyrrole, reacting for 3h at 30 ℃, respectively centrifugally washing for 3 times by using water and acetone to obtain the modified montmorillonite, and drying for later use.
(3) Accurately weighing 5g of the hydrotalcite solid powder after the lamella stripping prepared in the step (1) and 10g of the modified montmorillonite prepared in the step (2), adding the hydrotalcite solid powder and the modified montmorillonite into 1L of deionized water, shearing the mixture for 60min by using a high-shear disperser, centrifugally washing the mixture for 3 times by using the deionized water, drying the mixture in a blast drying oven at 110 ℃, and roasting the dried sample for 4 hours at 250 ℃ to prepare the nitrate radical treating agent.
Taking desulfurization and denitrification wastewater of an oil refinery, wherein the concentration of nitrate in the wastewater is 300mg/L, the concentration of sulfate radical in the wastewater is 2880mg/L, the dosage of a nitrate radical treating agent is 1g/L, the reaction time is 60min, after sedimentation is performed for 30min, supernatant is taken for detection, the concentration of nitrate radical in effluent is 102mg/L, the removal rate of nitrate radical is 66%, the concentration of sulfate radical in effluent is 2835mg/L, and the adsorption quantity of sulfate radical is 45mg/L, which shows that the treating agent has better selective adsorption effect on the nitrate radical in the desulfurization and denitrification wastewater.
After the treatment agent is saturated in adsorption, the treatment agent is placed in a muffle furnace for regeneration at 220 ℃, and the regenerated treatment agent is repeatedly used in the nitrate adsorption process of high-salt wastewater, so that the nitrate removal rate can be stably maintained at over 65 percent.
Example 2
The preparation method of the high-efficiency nitrate radical treating agent comprises the following steps:
(1) formulation 2LMg (NO) 3 ) 2 ·6H 2 O and Fe (NO) 3 ) 3 ·9H 2 Mixed salt solution A of O, Mg in solution 2+ The mass concentration of the substance is 0.8mol/L, Fe 3+ The mass concentration of the substance is 0.2 mol/L; configuration 2LNaOH and Na 2 CO 3 Mixed solution B, Na of 2 CO 3 The mass concentration of the substance is 0.4mol/L, and the mass concentration of the NaOH substance is 2.0 mol/L. After 4L of deionized water was added into a 10L reactor, the mixed salt solution A and the mixed solution B were added dropwise into the reactor at a dropping rate of 600ml/h while vigorously stirring, and the pH of the mixed and stirred solution in the reactor was controlled to 10. After titration, the slurry is stirred at the temperature of 60 ℃ and aged for 12 h. Filtering the formed hydrotalcite after aging, washing and filtering repeatedly for three times, transferring a filter cake into a crucible, drying for 12 hours in a drying oven at 105 ℃, and placing the product into a dryer for later use. Adding the hydrotalcite to be used into DMF according to the mass ratio of the hydrotalcite to the DMF of 1:20, carrying out ultrasonic treatment for 24 hours, then carrying out centrifugal separation, distilling to remove the DMF, washing the hydrotalcite with absolute ethyl alcohol, then placing the hydrotalcite into an oven to dry at 120 ℃, and grinding to obtain the hydrotalcite solid powder after lamella peeling.
(2) Weighing raw montmorillonite soil 2kg, pulverizing to less than 50 mesh, weighing the pulverized raw montmorillonite, adding into a plastic bucket, adding 20L deionized water, stirring with a stirrer for 60min, standing, removing the montmorillonite slurry on the upper layer, and removing the sand and stone on the lower layer. Adjusting the pH value of the montmorillonite slurry on the upper layer to acidity, then heating and flocculating for 15 minutes on an electric furnace, standing for a certain time at room temperature, centrifugally separating to remove partial water and salt, drying and grinding. Adding 200g of finely ground montmorillonite fine soil into 2L of deionized water, mechanically and violently stirring for 90min, and adding FeCl at the temperature of 25-35 DEG C 3 200g, then adding 25ml of pyrrole, reacting for 4h at 30 ℃, respectively centrifugally washing for 4 times by using water and acetone to obtain the modified montmorillonite, and drying for later use.
(3) Accurately weighing 15g of the hydrotalcite solid powder after the lamella stripping prepared in the step (1) and 5g of the modified montmorillonite prepared in the step (2), adding the hydrotalcite solid powder and the modified montmorillonite into 2L of deionized water, shearing the mixture for 90min by using a high-shear disperser, centrifugally washing the mixture for 3 times by using the deionized water, drying the mixture in a blast drying oven at 110 ℃, and roasting the dried sample for 4 hours at 300 ℃ to prepare the nitrate radical treating agent.
Taking desulfurization and denitrification wastewater of an oil refinery, wherein the nitrate concentration of the wastewater is 270mg/L, the sulfate concentration is 2830mg/L, the adding amount of a nitrate treating agent is 1g/L, the reaction time is 60min, after sedimentation is performed for 30min, supernatant is taken for detection, the nitrate concentration of effluent is 93mg/L, the removal rate of nitrate is 65.6%, the sulfate concentration of effluent is 2790mg/L, and the sulfate adsorption capacity is 40mg/L, which shows that the treating agent has a better selective adsorption effect on nitrate in the desulfurization and denitrification wastewater.
After the treatment agent is saturated in adsorption, the treatment agent is placed in a muffle furnace for regeneration at 220 ℃, and the regenerated treatment agent is repeatedly used in the nitrate adsorption process of high-salt wastewater, so that the nitrate removal rate can be stably maintained at over 65 percent.
Comparative example 1
The zinc-titanium-iron ternary hydrotalcite is prepared and then applied to desulfurization and denitrification wastewater of an oil refinery, the nitrate concentration of the wastewater is 270mg/L, the sulfate concentration is 2830mg/L, the adding amount of the zinc-titanium-iron ternary hydrotalcite is 1g/L, the reaction time is 60min, after sedimentation is carried out for 30min, a supernatant is taken for detection, the nitrate concentration of effluent is 142mg/L, the removal rate of nitrate is 47.4%, the sulfate concentration is 2620mg/L, and the sulfate adsorption capacity is 210 mg/L.
Comparative example 2
The hydrotalcite solid powder after the lamella stripping prepared in the step (1) in the embodiment 1 is applied to desulfurization and denitrification wastewater of a certain oil refinery, the nitrate concentration of the wastewater is 270mg/L, the sulfate radical concentration is 2830mg/L, the adding amount of the hydrotalcite is 1g/L, the reaction time is 60min, after the precipitation is carried out for 30min, a supernatant is taken for detection, the effluent nitrate concentration is 198mg/L, the nitrate removal rate is 26.7%, the effluent sulfate radical concentration is 2690mg/L, the sulfate radical adsorption amount is 140mg/L, and the removal effect is poor.
Comparative example 3
The pyrrole-modified montmorillonite prepared in the step (2) in the example 1 is independently applied to desulfurization and denitrification wastewater of a certain oil refinery, the nitrate concentration of the wastewater is 270mg/L, the sulfate concentration is 2830mg/L, the adding amount of hydrotalcite is 1g/L, the reaction time is 60min, after settling for 30min, a supernatant is taken for detection, the nitrate concentration of effluent is 185mg/L, the removal rate of nitrate is 31.5%, the sulfate concentration of effluent is 2810mg/L, and the sulfate adsorption capacity is 20 mg/L.
Comparative example 4
5g of the exfoliated hydrotalcite solid powder prepared in the step (1) in the example 1 and 15g of the pyrrole-modified montmorillonite prepared in the step (2) in the example 1 are added into 2L of deionized water, and are sheared for 90min by a high shear disperser, and then are centrifugally washed for 3 times by the deionized water, and then are dried in a forced air drying oven at 110 ℃, and the dried sample is roasted for 4h at 300 ℃ to prepare the nitrate radical treating agent.
The treating agent is used for desulfurization and denitrification wastewater of a certain oil refinery, the concentration of nitrate in the wastewater is 300mg/L, the concentration of sulfate radical in the wastewater is 2880mg/L, the dosage of the nitrate radical treating agent is 1g/L, the reaction time is 60min, after sedimentation is carried out for 30min, supernatant is taken for detection, the concentration of nitrate radical in effluent is 151mg/L, the removal rate of nitrate radical is 49.7%, the concentration of sulfate radical in effluent is 2792mg/L, and the adsorption quantity of sulfate radical is 88 mg/L.
Comparative example 5
10g of the exfoliated hydrotalcite solid powder prepared in the step (1) in the example 1 and 2.5g of the pyrrole-modified montmorillonite prepared in the step (2) in the example 1 are added into 2L of deionized water, and are sheared for 90min by a high-shear disperser, and then are centrifugally washed for 3 times by the deionized water, and then are dried in an air-blast drying oven at 110 ℃, and the dried sample is roasted for 4 hours at 300 ℃ to prepare the nitrate radical treating agent.
The treating agent is used for desulfurization and denitrification wastewater of a certain oil refinery, the concentration of nitrate in the wastewater is 300mg/L, the concentration of sulfate radical in the wastewater is 2880mg/L, the dosage of the nitrate radical treating agent is 1g/L, the reaction time is 60min, after sedimentation is carried out for 30min, supernate is taken for detection, the concentration of nitrate radical in effluent is 144mg/L, the removal rate of nitrate radical is 52%, the concentration of sulfate radical in effluent is 2821mg/L, and the adsorption capacity of sulfate radical is 59 mg/L.
Comparative example 6
The carbon nano tube and the powdered activated carbon are respectively applied to desulfurization and denitrification wastewater of a certain oil refinery, the nitrate concentration of the wastewater is 270mg/L, the adding amount of the carbon nano tube and the powdered activated carbon is 1g/L, the reaction time is 60min, after 30min of sedimentation, supernatant is taken for detection, the nitrate concentration of effluent water adsorbed by the carbon nano tube is 175mg/L, the removal rate of the nitrate is 35.2%, the nitrate concentration of effluent water adsorbed by the powdered activated carbon is 182mg/L, and the nitrate concentration is 32.6%.
Comparative example 7
The method comprises the steps of modifying commercially available zeolite with hydrochloric acid, and then applying the modified zeolite to desulfurization and denitrification wastewater of a certain oil refinery, wherein the nitrate concentration of the wastewater is 270mg/L, the adding amount of the modified zeolite is 1g/L, the reaction time is 60min, after settling for 30min, the supernatant is taken for detection, the nitrate concentration of effluent is 218mg/L, and the nitrate removal rate is 19.3%.
Comparative example 8
The zinc-titanium-iron ternary hydrotalcite is prepared and then applied to desulfurization and denitrification wastewater of an oil refinery, the nitrate concentration of the wastewater is 270mg/L, the sulfate concentration is 2830mg/L, the adding amount of the zinc-titanium-iron ternary hydrotalcite is 1g/L, the reaction time is 60min, after sedimentation is carried out for 30min, a supernatant is taken for detection, the nitrate concentration of effluent is 142mg/L, the removal rate of nitrate is 47.4%, the sulfate concentration is 2620mg/L, and the sulfate adsorption capacity is 210 mg/L.
Comparative example 9
The treating agent prepared in example 1 is applied to low-salt wastewater, the nitrate concentration in the wastewater is 190mg/L, sulfate ions cannot be basically detected, the adding amount of the nitrate treating agent is 0.5g/L, the reaction time is 60min, after sedimentation is carried out for 30min, supernate is taken for detection, the nitrate concentration of effluent is 7mg/L, and the nitrate removal rate is 96.3%.
Comparative example 10
The treating agent prepared in example 1 is applied to low-salt wastewater, the nitrate concentration in the wastewater is 190mg/L, sulfate ions cannot be basically detected, the adding amount of the nitrate treating agent is 1g/L, the reaction time is 60min, after sedimentation is carried out for 30min, a supernatant is taken for detection, the nitrate concentration of effluent is 5mg/L, and the nitrate removal rate is 97.4%.

Claims (9)

1. A preparation method of an efficient nitrate radical treating agent for adsorbing high-salinity wastewater is characterized by comprising the following steps: the method comprises the following steps:
stage one, preparing magnesium-iron hydrotalcite:
(1) preparation Mg(NO 3 ) 2 ·6H 2 O and Fe (NO) 3 ) 3 ·9H 2 Mixed salt solution A of O, NaOH and Na 2 CO 3 The mixed solution B of (1);
(2) adding deionized water into a reactor, dropwise adding the mixed salt solution A and the mixed solution B into the reactor, stirring simultaneously, and controlling the pH value of the mixed stirring liquid in the reactor to be 9-10;
(3) after the dropwise addition is finished, the slurry is subjected to heat preservation and stirring at 60 ℃, aged for 12 hours, the formed hydrotalcite is filtered and washed, and a filter cake is transferred to a crucible and dried for later use;
stage two, hydrotalcite stripping:
(4) adding the hydrotalcite prepared in the step (3) into N, N-dimethylformamide, carrying out ultrasonic treatment for 24 hours, then carrying out centrifugal separation, distilling to remove the N, N-dimethylformamide, washing with absolute ethyl alcohol, then putting into an oven for drying at 120 ℃, and grinding to obtain hydrotalcite solid powder after lamella stripping;
and step three, modifying the montmorillonite polypyrrole:
(5) crushing raw montmorillonite soil to be less than 50 meshes, adding the crushed raw montmorillonite soil into deionized water, stirring for 30-60 minutes, standing, removing montmorillonite slurry on the upper layer, and removing sand and stones on the lower layer; adjusting the pH value of the montmorillonite slurry to acidity, then heating and flocculating for 10-15 minutes, standing at room temperature, centrifugally separating, drying, and grinding to obtain montmorillonite fine soil;
(6) adding the refined montmorillonite soil into deionized water, stirring for 60-90 min, and adding FeCl with the same mass as the refined montmorillonite soil at a temperature of 25-35 DEG C 3 Then adding pyrrole, reacting for 3-4 h at 30 ℃, respectively centrifugally washing for 3-4 times by using water and acetone to obtain modified montmorillonite, and drying for later use;
stage four, intercalation compounding:
(7) adding the hydrotalcite solid powder obtained after the lamella stripping in the step (4) and the modified montmorillonite obtained in the step (6) into deionized water, shearing for 60-90 min by using a high-shear disperser, centrifugally washing for 3 times by using the deionized water, drying at 110 ℃ in a forced air drying oven, and roasting a dried sample at 250-300 ℃ for 4 hours to obtain a nitrate radical treating agent;
in the step (7), the mass ratio of the hydrotalcite solid powder subjected to the lamella stripping to the modified montmorillonite is 0.5: 1-3: 1.
2. the method for preparing a nitrate radical treating agent with high efficiency for adsorbing high-salinity wastewater according to claim 1, which is characterized in that: in the step (1), the mixed salt solution A contains Mg 2+ The mass concentration of the substance is 0.6-0.8 mol/L, Fe 3+ The mass concentration of the substances is 0.15-0.2 mol/L; in the mixed solution B, Na 2 CO 3 The amount concentration of the substance is 0.3-0.4 mol/L, and the amount concentration of the NaOH substance is 1.5-2 mol/L.
3. The method for preparing a nitrate radical treating agent with high efficiency for adsorbing high-salinity wastewater according to claim 1, which is characterized in that: in the step (2), the dropping speed is 600-800mL/h, and the volume ratio of the deionized water to the mixed salt solution A to the mixed solution B is 2:1: 1-2.5: 1: 1.
4. the method for preparing a nitrate radical treating agent with high efficiency for adsorbing high-salinity wastewater according to claim 1, which is characterized in that: in the step (3), the drying temperature is 105 ℃, and the drying time is 12 hours.
5. The method for preparing a nitrate radical treating agent with high efficiency for adsorbing high-salinity wastewater according to claim 1, which is characterized in that: in the step (4), the mass ratio of the hydrotalcite to the N, N-dimethylformamide is 1: 10-1: 20.
6. the method for preparing a nitrate radical treating agent with high efficiency for adsorbing high-salinity wastewater according to claim 1, which is characterized in that: in the step (5), the mass ratio of the montmorillonite raw soil to the deionized water is 0.05-0.2: 1.
7. the method for preparing a nitrate radical treating agent with high efficiency for adsorbing high-salinity wastewater according to claim 1, which is characterized in that: in the step (5), the granularity of the montmorillonite fine soil is less than 200 meshes.
8. The method for preparing a nitrate radical treating agent with high efficiency for adsorbing high-salinity wastewater according to claim 1, which is characterized in that: in the step (6), the mass ratio of the montmorillonite refined soil to the deionized water is 0.05-0.2: 1.
9. the method for preparing a nitrate radical treating agent with high efficiency for adsorbing high-salinity wastewater according to claim 1, which is characterized in that: in the step (6), the mass ratio of the pyrrole to the montmorillonite fine soil is 0.06-0.25: 1.
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