Method for removing fluorine, calcium, magnesium and silicon ions in wastewater by synchronous pellet directional induced crystallization

Abstract

The present application relates to wastewater treatment technical field, specifically to a kind of pellet directional induced crystallization synchronous removal of fluorine calcium magnesium silicon ion in wastewater method, the method is: using vacuum impregnation, crystal seed is immersed into composite treatment agent, the modification treatment of crystal seed is completed, using sodium metaaluminate as medicament, wastewater is treated, then adjust pH to 8.0-9.0, continue to treat wastewater can be.The present application, using composite treatment agent is modified to crystal seed, composite flocculating agent is embedded in the porous structure of crystal seed, so that when it contacts with calcium and magnesium ions, coordination chelation will occur, calcium and magnesium ions absorbed by coordination will be gathered and crowded together, flocculation occurs, thereby precipitation and separation occur, calcium and magnesium ions in wastewater are removed, at the same time, sodium metaaluminate is added, fluoride ion and silicon ion can be removed simultaneously, directly obtain fluorine-containing silicon-containing crystal, without sludge dewatering, low cost, high efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wastewater treatment, in particular to a method for directional induction crystallization of pellets to remove fluorine, calcium, magnesium and silicon ions in wastewater. BACKGROUND

[0002] Different coal gasification processes have very different coal gasification wastewater qualities. The low-temperature gasification technology has the characteristics of high chemical oxygen demand, high phenol, high ammonia nitrogen, high oil, and high turbidity. The water-coal slurry high-temperature and dry powder pressurized gasification technology has the characteristics of high ammonia nitrogen and high hardness, and low degree of organic pollution. The organic matter is easily biodegradable. The present technology is mainly aimed at coal gasification wastewater with high ammonia nitrogen, high turbidity, high hardness, and low concentration of organic matter. Coal gasification is an important branch of new coal chemical industry. In actual operation, a large amount of wastewater will be generated, so it is necessary to efficiently treat the coal gasification wastewater. Coal gasification wastewater mainly refers to the gray water quality overflowing from the gasifier. In fact, it is the gasifier and the washing tower that directly discharge the gasification ash water containing too much coal element. The main characteristics are high hardness, high ammonia nitrogen, and high suspended solids, containing a large amount of fluorine, calcium, magnesium, and silicon ions, which can easily cause blockage of heat exchangers, washing towers, and pipelines.

[0003] For example, Chinese patent CN115784408B discloses a method for removing phosphorus, fluorine, and heavy metals in wastewater by using modified seed crystals. Calcium ions or strong alkali modified seed crystals, or iron hydroxide colloid or aluminum hydroxide colloid modified seed crystals, or thiol functionalized modified seed crystals, or sulfur ion modified seed crystals are used. Calcium salt and strong alkali are used as crystallization reagents to remove phosphorus, fluorine, and heavy metals in wastewater. Although this method can remove phosphorus, fluorine, and heavy metals in wastewater, it cannot remove silicon ions. Moreover, the use of calcium salt and strong alkali as crystallization reagents added to wastewater will increase the concentration of calcium ions in wastewater, leading to increased wastewater hardness and unable to solve the problem of pipeline blockage. SUMMARY

[0004] In view of the problems in the prior art, the present application aims to provide a method for directional induction crystallization of pellets to remove fluorine, calcium, magnesium, and silicon ions in wastewater, which can efficiently remove fluorine, calcium, magnesium, and silicon ions in wastewater, thereby reducing wastewater hardness and solving the problem of pipeline blockage.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0006] A method for directional induction crystallization of pellets to remove fluorine, calcium, magnesium, and silicon ions in wastewater, which comprises the following steps: vacuum impregnation is used to immerse seed crystals into a composite treatment agent to complete the modification treatment of the seed crystals; sodium metaaluminate is used as a reagent to treat wastewater; and then the pH is adjusted to 8.0-9.0 to continue treating the wastewater, thereby completing the removal of fluorine, calcium, magnesium, and silicon ions in the wastewater.

[0007] The preparation method of the composite treatment agent is as follows: taking hollow mesoporous particles as carriers, sequentially infiltrating polymer flocculants, silver nanowires and flower-shaped nanoparticles into the carriers by vacuum impregnation under ultrasonic assistance to obtain a composite flocculant, and then uniformly dispersing the composite flocculant in a dispersion medium by ultrasonic dispersion, wherein ethanol / water mixed solvent is used as the dispersion medium and polyvinylpyrrolidone is used as a dispersion stabilizer.

[0008] The crystal seed is a porous structure of a poorly soluble solid particle.

[0009] As a further preferred scheme of the present application, the pH value of the wastewater is adjusted to 5.0-6.0 before treatment.

[0010] In the composite treatment agent, the content of the composite flocculant is 5-8wt%, and the content of polyvinylpyrrolidone is 1-3wt%.

[0011] As a further preferred scheme of the present application, the composite flocculant is prepared by the following method:

[0012] 1) Dissolve chitosan in acetic acid solution to prepare a chitosan solution, then add acrylamide, itaconic acid and the chitosan solution into a container, mix uniformly, adjust the pH value to 5.0-6.0, and then fill the container with nitrogen for 20-30min, then add an aqueous solution of azobisdimethylaminoformamide hydrochloride, seal and place in an ultrasonic device to react for 5-10h under a power of 200-300W, after the reaction is completed, the product is allowed to stand for 2-5h for curing, and then purified with anhydrous ethanol and acetone, vacuum dried at 90-95℃ until the weight is constant, and then ultra-finely ground to obtain a polymer flocculant;

[0013] 2) ultrasonically disperse the polymer flocculant in ethanol / water mixed solvent to obtain dispersion liquid A, ultrasonically disperse silver nanowires in ethanol / water mixed solvent to obtain dispersion liquid B, and ultrasonically disperse flower-shaped nanoparticles in ethanol / water mixed solvent to obtain dispersion liquid C for standby use;

[0014] 3) the hollow mesoporous particles are placed in a vacuum impregnation tank, vacuumed to 50-100 Pa and maintained for 10-20 min, then enough dispersion liquid A is injected, vacuumed to 10-30 Pa, and maintained for 20-30 min under the action of 200-300 W ultrasonic waves, after the treatment is completed, the pressure is slowly released to normal pressure, the excess dispersion liquid A is discharged, then vacuumed to 50-100 Pa again and maintained for 10-20 min, then enough dispersion liquid B is injected, vacuumed to 10-30 Pa, and maintained for 20-30 min under the action of 150-200 W ultrasonic waves, after the treatment is completed, the pressure is slowly released to normal pressure, the excess dispersion liquid B is discharged, then vacuumed to 50-100 Pa again and maintained for 10-20 min, then enough dispersion liquid C is injected, vacuumed to 10-30 Pa, and maintained for 20-30 min under the action of 100-150 W ultrasonic waves, after the treatment is completed, the pressure is slowly released to normal pressure, the product is centrifuged and washed repeatedly with deionized water and ethanol, and dried, to obtain the composite flocculant.

[0015] Further, in step 1), the concentration of the acetic acid solution is 1-3 wt%;

[0016] The concentration of the chitosan solution is 5-8 wt%;

[0017] The concentration of the aqueous azobisdimethylamid hydrochloride solution is 5-10 wt%;

[0018] The ratio of the acrylamide, itaconic acid, chitosan solution, and aqueous azobisdimethylamid hydrochloride solution is (3-6) g:(2-5) g:(60-100) mL:(10-15) mL.

[0019] Further, in step 2), the concentration of the ethanol / water mixed solvent is 70-80 wt%;

[0020] The solid content of the dispersion liquid A is 5-10 wt%;

[0021] The solid content of the dispersion liquid B is 8-13 wt%;

[0022] The solid content of the dispersion liquid C is 2-6 wt%.

[0023] As a further preferred scheme of the present application, the hollow mesoporous particles are prepared as follows:

[0024] 1) tetraethyl orthosilicate is quickly added to a mixture of ethanol, deionized water and ammonia solution, magnetically stirred at room temperature for 1-3 h, then centrifuged, and the obtained product is repeatedly washed with deionized water and ethanol and dried, to obtain solid silica microspheres;

[0025] 2) ultrasonic dispersion of the solid silica microspheres in deionized water, then addition of cetyltrimethylammonium bromide, stirring at room temperature for 1-3 h, then addition of anhydrous sodium carbonate, continued stirring at 35-40 °C for 10-15 h, then heating to 50-56 °C, continued stirring for 20-30 h, after the reaction is completed, centrifugal separation of the product, repeated washing with deionized water and ethanol, and drying to obtain the hollow mesoporous particles.

[0026] Further, in step 1), the volumes of the tetraethyl orthosilicate, ethanol, deionized water, and ammonia solution are (6-10) : (74-80) : (10-16) : (3.0-3.5) ;

[0027] The ammonia solution has a concentration of 25-28 wt%.

[0028] Further, in step 2), the proportions of the solid silica microspheres, deionized water, cetyltrimethylammonium bromide, and anhydrous sodium carbonate are (0.5-1.0) g : (90-150) mL : (10-15) mL : (2.1-2.5) g;

[0029] The cetyltrimethylammonium bromide has a concentration of 12.5-13.0 mg / mL.

[0030] As a further preferred aspect of the present application, the flower-shaped nanoparticles are prepared by the following method:

[0031] 1) addition of selenium powder to dimethylformamide, ultrasonic treatment for 30-50 min, then magnetic stirring for 2-5 h, then addition of sodium borohydride, continued magnetic stirring for 2-5 h to obtain solution A, weighing of sodium tungstate into 10-30 mL of deionized water, ultrasonic treatment for 30-50 min, then magnetic stirring for 1-3 h to obtain solution B, ready for use;

[0032] 2) dropwise addition of solution B to solution A, magnetic stirring for 2-5 h, then transfer to a high-temperature reaction kettle, heating and holding for 48-52 h, after the reaction is completed, natural cooling to room temperature, repeated washing of the bottom material with anhydrous ethanol and deionized water, then placement in a sufficient amount of sodium hydroxide solution, centrifugal separation after sufficient stirring, and drying to obtain the flower-shaped nanoparticles.

[0033] Further, the proportions of the solution A, selenium powder, dimethylformamide, and sodium borohydride are (0.6-1.0) g : (60-100) mL : (0.2-0.5) g;

[0034] The proportions of the solution B, sodium tungstate, and deionized water are (1.3-1.8) g : (10-30) mL;

[0035] The volume ratio of the solution B to the solution A is (10-30):(60-100).

[0036] The heating and keeping warm is at a temperature of 220-230 DEG C.

[0037] The concentration of the sodium hydroxide solution is 1.0-1.5 mol / L.

[0038] Compared with the prior art, the present application has the following beneficial effects:

[0039] In the application, chitosan, acrylamide and itaconic acid are selected as grafting monomers, and a polymer flocculant rich in carboxylic acid groups is prepared by ultrasonic radical initiation polymerization, which has chelation and flocculation effects, can chelate and fix calcium and magnesium ions through the contained carboxyl groups, and then generate large and dense metal floc structures under the adsorption bridging and net capture and sweeping effects, so as to settle and achieve good calcium and magnesium ion removal effect; in order to make the polymer flocculant have better flocculation effect, the polymer flocculant is subjected to ultrafine grinding treatment in the application, the particle size thereof is reduced, the surface area thereof is increased, and more chelation sites are provided, so that the polymer flocculant can better adsorb and flocculate and settle calcium and magnesium ions, and high removal rate of calcium and magnesium ions is realized; however, as the particle size of the polymer flocculant is reduced, the polymer flocculant is prone to loss when applied to wastewater, therefore, the polymer flocculant is processed in the application, hollow mesoporous particles are synthesized by a self-template method, the polymer flocculant is injected into the porous space of the hollow mesoporous particles by vacuum impregnation in cooperation with ultrasonic auxiliary effect, the ultrasonic auxiliary effect can promote the polymer flocculant to fully penetrate into the interspaces of the carrier, and help to improve the loading rate of the carrier; meanwhile, silver nanowires are also injected into the carrier by vacuum impregnation in cooperation with ultrasonic auxiliary effect, a reticular structure is formed by the mutual entanglement and crosslinking of the silver nanowires, the polymer flocculant is wrapped by the reticular structure, so that the polymer flocculant is fixed in the interspaces of the carrier and is not easy to separate, and the power of the auxiliary ultrasonic effect is lower than that of the first time, so that the amount of the silver nanowires penetrating into the interspaces of the carrier is not too large, and the polymer flocculant is not squeezed out of the interspaces of the carrier; meanwhile, in order to further enhance the fixing effect of the polymer flocculant in the carrier, selenium powder and sodium tungstate are used as selenium source and tungsten source to synthesize flower-shaped nanoparticles by hydrothermal reaction, the nanoparticles have a three-dimensional flower ball shape and a large number of petal-shaped protrusions on the surface, the nanoparticles are injected into the carrier by vacuum impregnation in cooperation with ultrasonic auxiliary effect, the power of the ultrasonic auxiliary effect is lower than that of the previous two times, so that a large number of flower-shaped nanoparticles are only embedded at the entrances of the mesoporous channels of the carrier, and cannot enter the deep part of the mesoporous channels, the flower-shaped nanoparticles embedded at the entrances of the mesoporous channels can further prevent the polymer flocculant from separating from the carrier, and as the surface of the flower-shaped nanoparticles has a large number of petal-shaped protrusions, the flower-shaped nanoparticles embedded at the entrances of the mesoporous channels cannot completely close the entrances, so as to leave channels for subsequent calcium and magnesium ions, and therefore the capture of the polymer flocculant on the calcium and magnesium ions is not affected.

[0040] In the present application, the prepared composite flocculant is dispersed in a mixed solvent to form a composite treatment liquid, and then the composite flocculant is infiltrated into the seed crystal by vacuum impregnation, so that the composite flocculant is embedded in the porous structure of the seed crystal, and the modification treatment of the seed crystal is completed. At the same time, due to the embedded silver nanowires in the composite flocculant, part of the external surface is exposed to form a large amount of whisker structure. After the composite flocculant is embedded in the porous structure of the seed crystal, a large amount of whisker structure will be entangled with the winding porous structure in the seed crystal, and a part will be crosslinked with each other to connect the composite flocculant to form an aggregate, so that it can be more firmly embedded in the seed crystal. The composite flocculant contains carboxyl groups with strong adsorption capacity and active -NH2 and hydroxyl adsorption groups. When in contact with calcium and magnesium ions, coordination chelation will occur. As the number of calcium and magnesium ions adsorbed and captured on the molecular chain of the fixed composite flocculant increases, the molecular chain will aggregate and cluster the coordination adsorbed calcium and magnesium ions together through adsorption bridging and net capture sweeping effect, and flocculation will occur. Finally, large and dense metal ion floc structure is generated, thereby precipitation and separation occur, and calcium and magnesium ions in wastewater are removed. At the same time, the added sodium metaaluminate forms a hydrolyzed transition state of aluminum hydroxide in an acidic system, and forms a positively charged colloidal particle in water to adsorb fluoride ions in wastewater, so that the colloidal particles are aggregated into larger flocculent and co-precipitated with the seed crystal. At the same time, by adjusting the pH value of the defluorinated wastewater, the silicon-containing compounds in the wastewater are decomposed into silicate ions and form silicates, which generate complex salts with sodium metaaluminate and continuously precipitate on the seed crystal, thereby realizing the removal of fluorine and silicon ions in wastewater.

[0041] The method for removing fluorine, calcium, magnesium and silicon ions in wastewater in the present application uses a composite treatment agent to modify the seed crystal, and embeds the composite flocculant in the porous structure of the seed crystal. When in contact with calcium and magnesium ions, coordination chelation will occur, calcium and magnesium ions will be aggregated and clustered together, flocculation will occur, and precipitation and separation will occur, thereby removing calcium and magnesium ions in wastewater. At the same time, the added sodium metaaluminate can remove fluoride and silicon ions at the same time, directly obtain fluorine and silicon-containing crystals, and does not need sludge dewatering, which is low in cost and high in efficiency. DETAILED DESCRIPTION

[0042] The technical solutions in the embodiments of the present application will be described below. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0043] In the present embodiment, the wastewater is derived from coal washing plant gasification ash water and ammonia evaporation wastewater.

[0044] Embodiment 1

[0045] The method for removing fluorine, calcium, magnesium and silicon ions in wastewater by pellet directional induced crystallization synchronization, the specific operation is as follows: the crystal seed is immersed into the composite treatment agent by vacuum immersion method to complete the modification treatment of the crystal seed, and is put into the precipitation area of the reactor, the pH value of the wastewater is adjusted to 5.0, the sodium metaaluminate is used as the reagent, and is put into the precipitation area of the reactor together with the wastewater, and the wastewater is treated by flocculation and precipitation to complete the first treatment of the wastewater, then the pH value of the wastewater is adjusted to 8.0, the wastewater is treated for the second time, so that the removal of fluorine, calcium, magnesium and silicon ions in the wastewater is completed;

[0046] The wastewater flow is 240 m 3 / h, the feeding amount of the crystal seed is 0.5 t / h, and the feeding amount of the sodium metaaluminate is 0.07 t / h;

[0047] The crystal seed is a porous calcite with a porous structure;

[0048] The preparation method of the composite treatment agent is as follows: the ethanol / water mixed solvent is used as the dispersion medium, the polyvinylpyrrolidone is used as the dispersion stabilizer, the composite flocculant is uniformly dispersed in the dispersion medium by ultrasonic dispersion method, and the like, wherein the content of the composite flocculant is 5wt%, and the content of the polyvinylpyrrolidone is 1wt%.

[0049] The preparation method of the composite flocculant is as follows:

[0050] 1) 6 mL of tetraethyl orthosilicate is quickly added into a mixture of 74 mL of ethanol, 10 mL of deionized water and 3.0 mL of ammonia water solution with a concentration of 25wt%, and is stirred at room temperature by a magnetic stirrer for 1 h, then is centrifuged at 4000 r / min for 10 min, and then is washed repeatedly with deionized water and ethanol and is dried to obtain solid silica microspheres;

[0051] 2) 0.5 g of the solid silica microspheres is ultrasonically dispersed in 90 mL of deionized water, then 10 mL of cetyltrimethylammonium bromide with a concentration of 12.5 mg / mL is added, and is stirred at 100 r / min at room temperature for 1 h, then 2.1 g of anhydrous sodium carbonate is added, and is continuously stirred at 35℃ for 10 h, then is heated to 50℃, and is continuously stirred for 20 h, after the reaction is completed, the product is centrifuged, is washed repeatedly with deionized water and ethanol, and is dried to obtain hollow mesoporous particles;

[0052] 3) 0.6 g selenium powder was added into 60 mL dimethylformamide, and after ultrasonic treatment at 200 W for 30 min, magnetic stirring was carried out at 500 r / min for 2 h, then 0.2 g sodium borohydride was added, and magnetic stirring was continued at 600 r / min for 2 h to obtain solution A; 1.3 g sodium tungstate was weighed into 10 mL deionized water, and after ultrasonic treatment at 200 W for 30 min, magnetic stirring was carried out at 600 r / min for 1 h to obtain solution B, which was ready for use;

[0053] 4) 10 mL solution B was added dropwise into 60 mL solution A, and magnetic stirring was carried out at 600 r / min for 2 h, then it was transferred into a high-temperature reaction kettle, and heated at 220℃ for 48 h; after the reaction was completed, it was naturally cooled to room temperature, and the bottom material was repeatedly washed with anhydrous ethanol and deionized water, and then placed in sufficient 1.0 mol / L sodium hydroxide solution, and after sufficient stirring, centrifugal separation was carried out, and after drying, flower-shaped nanoparticles were obtained;

[0054] 5) Cystose used a concentration of 1 wt% acetic acid solution to prepare a concentration of 5 wt% cystose solution, then 3 g acrylamide, 2 g itaconic acid and 60 mL cystose solution were added into a container, mixed uniformly, adjusted to pH 5.0, and then 20 min nitrogen was filled into the container, then 10 mL 5 wt% azobisdimethylamidinium hydrochloride aqueous solution was added, sealed and placed in an ultrasonic device, reacted at 200 W power for 5 h, after the reaction was completed, the product was allowed to stand for 2 h, and then purified with anhydrous ethanol and acetone, and vacuum dried at 90℃ to constant weight, and then ultra-finely pulverized to obtain a polymer flocculant;

[0055] 6) The polymer flocculant was ultrasonically dispersed in a concentration of 70 wt% ethanol / water mixed solvent to obtain a dispersion A with a solid content of 5 wt%, silver nanowires were ultrasonically dispersed in a concentration of 70 wt% ethanol / water mixed solvent to obtain a dispersion B with a solid content of 8 wt%, and flower-shaped nanoparticles were ultrasonically dispersed in a concentration of 70 wt% ethanol / water mixed solvent to obtain a dispersion C with a solid content of 2 wt%, which was ready for use;

[0056] 7) The hollow mesoporous particles are placed in a vacuum impregnation tank, vacuumed to 50 Pa and maintained for 10 min, then a sufficient amount of dispersion liquid A is injected, vacuumed to 10 Pa, and maintained for 20 min under the action of 200 W ultrasonic waves, after the treatment is completed, the pressure is slowly released to normal pressure, the excess dispersion liquid A is discharged, then vacuumed to 50 Pa again and maintained for 10 min, then a sufficient amount of dispersion liquid B is injected, vacuumed to 10 Pa, and maintained for 20 min under the action of 150 W ultrasonic waves, after the treatment is completed, the pressure is slowly released to normal pressure, the excess dispersion liquid B is discharged, then vacuumed to 50 Pa again and maintained for 10 min, then a sufficient amount of dispersion liquid C is injected, vacuumed to 10 Pa, and maintained for 20 min under the action of 100 W ultrasonic waves, after the treatment is completed, the pressure is slowly released to normal pressure, the product is centrifuged and washed repeatedly with deionized water and ethanol, and then dried, to obtain the composite flocculant.

[0057] Example 2

[0058] A method for simultaneously removing fluorine, calcium, magnesium and silicon ions in wastewater by pellet directional induced crystallization, the specific operation is as follows: the crystal seeds are immersed into the composite treatment agent by vacuum impregnation to complete the modification treatment of the crystal seeds, and then the crystal seeds are put into the precipitation area of the reactor, the pH value of the wastewater is adjusted to 5.5, sodium metaaluminate is used as a reagent, and the wastewater and the reagent enter the precipitation area of the reactor, and after flocculation and precipitation, the first treatment of the wastewater is completed, then the pH value of the wastewater is adjusted to 8.5, and the second treatment of the wastewater is carried out, so as to complete the removal of fluorine, calcium, magnesium and silicon ions in the wastewater.

[0059] The flow rate of the wastewater is 240 m 3 / h, the amount of the crystal seeds is 0.5 t / h, and the amount of the sodium metaaluminate is 0.07 t / h.

[0060] The crystal seeds are porous calcite with a porous structure.

[0061] The preparation method of the composite treatment agent is as follows: an ethanol / water mixed solvent is used as a dispersion medium, polyvinylpyrrolidone is used as a dispersion stabilizer, and the composite flocculant is uniformly dispersed in the dispersion medium by ultrasonic dispersion.

[0062] The preparation method of the composite flocculant is as follows:

[0063] 1) 8 mL of tetraethyl orthosilicate is quickly added to a mixture of 75 mL of ethanol, 15 mL of deionized water and 3.2 mL of an ammonia water solution with a concentration of 26 wt%, and then magnetically stirred at room temperature for 2 h, then centrifuged at 5000 r / min for 15 min, and then washed repeatedly with deionized water and ethanol, and dried, to obtain solid silica microspheres.

[0064] 2) 0.8 g of solid silica microspheres was ultrasonically dispersed in 130 mL of deionized water, then 13 mL of cetyltrimethylammonium bromide with a concentration of 13.0 mg / mL was added, stirred at 130 r / min for 2 h at room temperature, then 2.3 g of anhydrous sodium carbonate was added, and the stirring was continued at 38℃ for 13 h, then the temperature was raised to 54℃, and the stirring was continued for 25 h. After the reaction was completed, the product was centrifuged, washed repeatedly with deionized water and ethanol, and dried to obtain hollow mesoporous particles;

[0065] 3) 0.8 g of selenium powder was added to 80 mL of dimethylformamide, and ultrasonically treated at 250 W for 40 min, then magnetically stirred at 700 r / min for 3 h, then 0.3 g of sodium borohydride was added, and magnetically stirred at 800 r / min for 3 h to obtain solution A. 1.5 g of sodium tungstate was weighed and placed in 20 mL of deionized water, ultrasonically treated at 250 W for 40 min, then magnetically stirred at 800 r / min for 2 h to obtain solution B, which was ready for use;

[0066] 4) 20 mL of solution B was added dropwise to 80 mL of solution A, and magnetically stirred at 800 r / min for 3 h, then transferred to a high-temperature reaction kettle, heated at 225℃ for 50 h, and then naturally cooled to room temperature. The bottom material was repeatedly washed with anhydrous ethanol and deionized water, and then placed in a sufficient amount of 1.3 mol / L sodium hydroxide solution, stirred thoroughly, centrifuged, and dried to obtain flower-shaped nanoparticles;

[0067] 5) Cystose was dissolved in a 2 wt% acetic acid solution to prepare a 7 wt% cystose solution. Then 5 g of acrylamide, 3 g of itaconic acid, and 80 mL of the cystose solution were added to a container, mixed uniformly, adjusted to pH 5.5, and then filled with 25 min nitrogen. Then 13 mL of 8 wt% azobisdimethylamino formamide hydrochloride aqueous solution was added, sealed, and placed in an ultrasonic device for 8 h at a power of 300 W. After the reaction was completed, the product was allowed to mature for 3 h, and then purified with anhydrous ethanol and acetone. After vacuum drying at 92℃ to a constant weight, the product was ultra-finely ground to obtain a polymer flocculant;

[0068] 6) The polymer flocculant was ultrasonically dispersed in a 75 wt% ethanol / water mixed solvent to obtain a dispersion A with a solid content of 8 wt%. Silver nanowires were ultrasonically dispersed in a 75 wt% ethanol / water mixed solvent to obtain a dispersion B with a solid content of 10 wt%. Flower-shaped nanoparticles were ultrasonically dispersed in a 75 wt% ethanol / water mixed solvent to obtain a dispersion C with a solid content of 5 wt%, which was ready for use;

[0069] 7) The hollow mesoporous particles are placed in a vacuum impregnation tank, vacuumed to 80 Pa and maintained for 15 min, then a sufficient amount of dispersion liquid A is injected, vacuumed to 20 Pa, and maintained for 25 min under the action of 250 W ultrasonic waves, after the treatment is completed, the pressure is slowly released to normal pressure, the excess dispersion liquid A is discharged, vacuumed to 850 Pa again, and maintained for 15 min, then a sufficient amount of dispersion liquid B is injected, vacuumed to 20 Pa, and maintained for 25 min under the action of 180 W ultrasonic waves, after the treatment is completed, the pressure is slowly released to normal pressure, the excess dispersion liquid B is discharged, vacuumed to 80 Pa again, and maintained for 15 min, then a sufficient amount of dispersion liquid C is injected, vacuumed to 20 Pa, and maintained for 25 min under the action of 120 W ultrasonic waves, after the treatment is completed, the pressure is slowly released to normal pressure, the product is centrifuged and washed repeatedly with deionized water and ethanol, and after drying, the composite flocculant is obtained.

[0070] Example 3

[0071] A method for synchronously removing fluorine, calcium, magnesium and silicon ions in wastewater by pellet directional induced crystallization, the specific operation is as follows: the crystal seeds are immersed into the composite treatment agent by vacuum impregnation to complete the modification treatment of the crystal seeds, and are put into the precipitation zone of the reactor, the pH value of the wastewater is adjusted to 6.0, sodium metaaluminate is used as a reagent, and the wastewater enters the precipitation zone of the reactor together, after flocculation and precipitation, the first treatment of the wastewater is completed, then the pH value of the wastewater is adjusted to 9.0, the wastewater is treated for the second time, and thus the removal of fluorine, calcium, magnesium and silicon ions in the wastewater is completed.

[0072] The wastewater flow is 240 m 3 / h, the dosage of the crystal seeds is 0.5 t / h, and the dosage of sodium metaaluminate is 0.07 t / h.

[0073] The crystal seeds are porous calcite with a porous structure.

[0074] The preparation method of the composite treatment agent is as follows: an ethanol / water mixed solvent is used as a dispersion medium, polyvinylpyrrolidone is used as a dispersion stabilizer, and the composite flocculant is uniformly dispersed in the dispersion medium by ultrasonic dispersion, wherein the content of the composite flocculant is 8 wt%, and the content of the polyvinylpyrrolidone is 3 wt%.

[0075] The preparation method of the composite flocculant is as follows:

[0076] 1) 10 mL of tetraethyl orthosilicate is quickly added to a mixture of 80 mL of ethanol, 16 mL of deionized water and 3.5 mL of an ammonia water solution with a concentration of 28 wt%, the mixture is magnetically stirred at room temperature for 3 h, then centrifuged at 6000 r / min for 20 min, the obtained product is repeatedly washed with deionized water and ethanol, and dried to obtain solid silica microspheres.

[0077] 2) 1.0 g of solid silica microspheres was ultrasonically dispersed in 150 mL of deionized water, then 15 mL of cetyltrimethylammonium bromide with a concentration of 13.0 mg / mL was added, stirred at 150 r / min for 3 h at room temperature, then 2.5 g of anhydrous sodium carbonate was added, and the stirring was continued at 40℃ for 15 h, then the temperature was raised to 56℃, and the stirring was continued for 30 h. After the reaction was completed, the product was centrifuged, washed repeatedly with deionized water and ethanol, and dried to obtain hollow mesoporous particles;

[0078] 3) 1.0 g of selenium powder was added to 100 mL of dimethylformamide, ultrasonically treated at 300 W for 50 min, then magnetically stirred at 800 r / min for 5 h, then 0.5 g of sodium borohydride was added, and the magnetic stirring was continued at 1000 r / min for 5 h to obtain solution A. 1.8 g of sodium tungstate was weighed and placed in 30 mL of deionized water, ultrasonically treated at 300 W for 50 min, then magnetically stirred at 1000 r / min for 3 h to obtain solution B, which was prepared for use;

[0079] 4) 30 mL of solution B was added dropwise to 100 mL of solution A, magnetically stirred at 1000 r / min for 5 h, then transferred to a high-temperature reaction kettle, heated at 230℃ for 52 h, and then naturally cooled to room temperature. The bottom material was repeatedly washed with anhydrous ethanol and deionized water, then placed in a sufficient amount of 1.5 mol / L sodium hydroxide solution, stirred thoroughly, centrifuged, dried, and then the flower-shaped nanoparticles were obtained;

[0080] 5) Cystose was dissolved in a 3wt% acetic acid solution to prepare a 8wt% cystose solution. Then 6 g of acrylamide and 5 g of itaconic acid were added to a container with 100 mL of the cystose solution, mixed uniformly, adjusted to pH 6.0, and then filled with 30 min of nitrogen. Then 15 mL of 10wt% azobisdimethylaminoformamide hydrochloride aqueous solution was added, sealed, and placed in an ultrasonic device for 10 h at a power of 300 W. After the reaction was completed, the product was allowed to mature for 5 h, purified with anhydrous ethanol and acetone, vacuum dried at 95℃ until the weight was constant, and then ultra-finely ground to obtain a polymer flocculant;

[0081] 6) The polymer flocculant was ultrasonically dispersed in an 80wt% ethanol / water mixed solvent to obtain a dispersion A with a solid content of 10wt%. Silver nanowires were ultrasonically dispersed in an 80wt% ethanol / water mixed solvent to obtain a dispersion B with a solid content of 13wt%. Flower-shaped nanoparticles were ultrasonically dispersed in an 80wt% ethanol / water mixed solvent to obtain a dispersion C with a solid content of 6wt%. These dispersions were prepared for use;

[0082] 7) The hollow mesoporous particles are placed in a vacuum impregnation tank, vacuumed to 100 Pa and maintained for 20 min, then enough dispersion liquid A is injected, vacuumed to 30 Pa, and maintained for 30 min under the action of 300 W ultrasonic waves, after the treatment is completed, the pressure is slowly released to normal pressure, the excess dispersion liquid A is discharged, then vacuumed to 100 Pa again and maintained for 20 min, then enough dispersion liquid B is injected, vacuumed to 30 Pa, and maintained for 30 min under the action of 200 W ultrasonic waves, after the treatment is completed, the pressure is slowly released to normal pressure, the excess dispersion liquid B is discharged, then vacuumed to 100 Pa again and maintained for 20 min, then enough dispersion liquid C is injected, vacuumed to 30 Pa, and maintained for 30 min under the action of 150 W ultrasonic waves, after the treatment is completed, the pressure is slowly released to normal pressure, the product is centrifuged and separated, then washed repeatedly with deionized water and ethanol, dried, and the composite flocculant is obtained.

[0083] Comparative Example 1: This comparative example is basically the same as Example 1, except that the crystal seeds are not modified.

[0084] Comparative Example 2: This comparative example is basically the same as Example 1, except that sodium metaaluminate is not added.

[0085] Comparative Example 3: This comparative example is basically the same as Example 1, except that a polymer flocculant is used instead of a composite flocculant.

[0086] Comparative Example 4: This comparative example is basically the same as Example 1, except that steps 3) to 4) are omitted in the preparation of the composite flocculant.

[0087] Comparative Example 5: This comparative example is basically the same as Example 1, except that silver nanowires in step 6) are omitted in the preparation of the composite flocculant.

[0088] Test experiment:

[0089] The methods disclosed in Examples 1 to 3 and Comparative Examples 1 to 5 are used respectively to complete the modification of the crystal seed porous calcite, then 83.3 g of the crystal seed after modification is added into the precipitation zone of the same type of reactor, 40 L of coal gasification wastewater (wastewater is gasification wastewater from a coal washing plant of a certain energy group and ammonia distillation wastewater, in the raw wastewater, fluorine is 1.250 mmol / L, calcium is 16.560 mmol / L, magnesium is 0.830 mmol / L, and silicon is 2.350 mmol / L), the pH value of the wastewater is adjusted to 6.0, then 11.6 g of sodium metaaluminate is added into the reactor precipitation zone, after sufficient flocculation and precipitation, the pH value of the wastewater is adjusted to 9.0, the wastewater is further treated, after the wastewater is treated, the water is taken out, the values of fluorine, calcium, magnesium and silicon ions in the water are measured, and the removal rate is calculated, and the results are shown in Table 1.

[0090] Table 1

[0091]

[0092]

[0093] It can be seen from Table 1 that the treatment method provided by the application can efficiently remove fluorine, calcium, magnesium and silicon ions in wastewater, thereby reducing the hardness of the wastewater and solving the problem of pipeline blockage.

[0094] The preferred embodiments of the application disclosed above are only used for helping to explain the application. The preferred embodiments do not describe all the details and limit the application to the specific embodiments. Obviously, according to the content of the specification, many modifications and changes can be made. The specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the application, so that the persons skilled in the art can well understand and utilize the application. The application is limited by the claims and the entire scope and equivalents thereof.

Claims

1. A method for the simultaneous removal of fluorine, calcium, magnesium and silicon ions from wastewater by oriented induction crystallization of pellets, characterized in that, The method is: using the way of vacuum impregnation, the seed is immersed into the composite treating agent, the modification treatment of the seed is completed, sodium metaaluminate is used as the reagent to treat the waste water, then the pH is adjusted to 8.0-9.0, the waste water is continuously treated, and the removal of fluorine, calcium, magnesium and silicon ions in the waste water is completed; The preparation method of the composite treating agent is: taking hollow mesoporous particles as the carrier, under the assistance of ultrasonic, the polymer flocculant, silver nanowire and flower-shaped nanoparticles are sequentially infiltrated into the carrier by the way of vacuum impregnation, and the ultrasonic power for infiltrating the above three substances into the carrier is sequentially decreased, to obtain the composite flocculant, then taking ethanol / water mixed solvent as the dispersion medium and polyvinylpyrrolidone as the dispersion stabilizer, the composite flocculant is uniformly dispersed in the dispersion medium by the method of ultrasonic dispersion. The seed is a porous structure of insoluble solid particles.

2. The method for removing fluorine, calcium, magnesium and silicon ions in wastewater synchronously by oriented induction crystallization of pellets according to claim 1, characterized in that, The pH of the waste water is adjusted to 5.0-6.0 before treatment; The content of the composite flocculant in the composite treating agent is 5-8wt%, and the content of polyvinylpyrrolidone is 1-3wt%.

3. A method for the simultaneous removal of fluoride, calcium, magnesium and silicon ions from wastewater by directed induction crystallization of pellets according to claim 1, characterized in that, The preparation method of the composite flocculant is as follows: 1) dissolve chitosan in acetic acid solution to prepare chitosan solution, then add acrylamide, itaconic acid and chitosan solution into a container, mix uniformly, adjust the pH to 5.0-6.0, fill 20-30min nitrogen into the container, then add azobisdimethylaminoformamide hydrochloride aqueous solution, seal and place in an ultrasonic device, react for 5-10h under the power of 200-300W, after the reaction is completed, the product is aged for 2-5h, and purified with anhydrous ethanol and acetone, vacuum dried to constant weight at 90-95℃, and then ultrafine ground to obtain the polymer flocculant; 2) ultrasonic dispersion of the polymer flocculant in ethanol / water mixed solvent to obtain dispersion A, ultrasonic dispersion of silver nanowire in ethanol / water mixed solvent to obtain dispersion B, and ultrasonic dispersion of flower-shaped nanoparticles in ethanol / water mixed solvent to obtain dispersion C for standby use. 3) Put the hollow mesoporous particles into a vacuum impregnation tank, vacuumize to 50-100 Pa and maintain for 10-20 min, then inject enough dispersion liquid A, vacuumize to 10-30 Pa, and maintain for 20-30 min under the action of 200-300 W ultrasonic, after the treatment is finished, slowly release the pressure to normal pressure, discharge the excessive dispersion liquid A, vacuumize to 50-100 Pa again and maintain for 10-20 min, then inject enough dispersion liquid B, vacuumize to 10-30 Pa, and maintain for 20-30 min under the action of 150-200 W ultrasonic, after the treatment is finished, slowly release the pressure to normal pressure, discharge the excessive dispersion liquid B, vacuumize to 50-100 Pa again and maintain for 10-20 min, then inject enough dispersion liquid C, vacuumize to 10-30 Pa, and maintain for 20-30 min under the action of 100-150 W ultrasonic, after the treatment is finished, slowly release the pressure to normal pressure, centrifugalize the product, wash repeatedly with deionized water and ethanol, and dry, then the composite flocculant can be obtained.

4. The method for removing fluorine, calcium, magnesium and silicon ions in wastewater synchronously by oriented induction crystallization of pellets according to claim 3, characterized in that, In step 1), the concentration of the acetic acid solution is 1-3 wt%; The concentration of the chitosan solution is 5-8 wt%; The concentration of the aqueous solution of azobisdimethylamidinum hydrochloride is 5-10 wt%; The ratio of the acrylamide, itaconic acid, chitosan solution, and aqueous solution of azobisdimethylamidinum hydrochloride is (3-6) g:(2-5) g:(60-100) mL:(10-15) mL.

5. The method for removing fluoride, calcium, magnesium and silicon ions from wastewater in a synchronous manner by oriented induction crystallization of pellets according to claim 3, characterized in that, In step 2), the concentration of the ethanol / water mixed solvent is 70-80 wt%; The solid content of the dispersion liquid A is 5-10 wt%; The solid content of the dispersion liquid B is 8-13 wt%; The solid content of the dispersion liquid C is 2-6 wt%.

6. A method for the simultaneous removal of fluoride, calcium, magnesium and silicon ions from wastewater by directed induction crystallization of pellets according to claim 1, characterized in that, The preparation method of the hollow mesoporous particles is as follows: 1) quickly add tetraethyl orthosilicate into the mixture of ethanol, deionized water and ammonia solution, magnetically stir at room temperature for 1-3 h, then centrifugalize, wash repeatedly with deionized water and ethanol alternately, and dry, to obtain solid silica microspheres; 2) ultrasonically disperse the solid silica microspheres in deionized water, then add cetyltrimethylammonium bromide, stir at room temperature for 1-3 h, then add anhydrous sodium carbonate, continue to stir at 35-40 ℃ for 10-15 h, then heat to 50-56 ℃, continue to stir for 20-30 h, after the reaction is finished, centrifugalize the product, wash repeatedly with deionized water and ethanol alternately, and dry, to obtain hollow mesoporous particles.

7. A method for the simultaneous removal of fluoride, calcium, magnesium and silicon ions from wastewater by directed induction crystallization of pellets according to claim 6, characterized in that, In step 1), the volume of the tetraethyl orthosilicate, ethanol, deionized water, and ammonia solution is (6-10):(74-80):(10-16):(3.0-3.5); The concentration of the ammonia solution is 25-28 wt%.

8. A method for the simultaneous removal of fluoride, calcium, magnesium and silicon ions from wastewater by directed induction crystallization of pellets according to claim 6, characterized in that, In step 2), the ratio of the solid silica microspheres, deionized water, cetyltrimethylammonium bromide, and anhydrous sodium carbonate is (0.5-1.0) g:(90-150) mL:(10-15) mL:(2.1-2.5) g; The cetyl trimethyl ammonium bromide has a concentration of 12.5-13.0 mg / mL.

9. A method for the simultaneous removal of fluoride, calcium, magnesium and silicon ions from wastewater by directed induction crystallization of pellets according to claim 1, characterized in that, The flower-shaped nanoparticles are prepared by the following method: 1) Se powder is added into dimethyl formamide, and then ultrasonic treatment is conducted for 30-50 min, magnetic stirring is conducted for 2-5 h, NaBH4 is added, magnetic stirring is conducted for 2-5 h, solution A is obtained, Na2WO4 is weighed and placed in 10-30 mL deionized water, ultrasonic treatment is conducted for 30-50 min, magnetic stirring is conducted for 1-3 h, and solution B is obtained and reserved; 2) Solution B is added dropwise into solution A, magnetic stirring is conducted for 2-5 h, then the mixture is transferred into a high-temperature reaction kettle, heating and preservation are conducted for 48-52 h, after the reaction is completed, natural cooling is conducted to room temperature, the bottom substance is repeatedly washed with anhydrous ethanol and deionized water, and then the substance is placed in sufficient NaOH solution, after sufficient stirring, centrifugal separation is conducted, and after drying, flower-shaped nanoparticles are obtained.

10. The method for the directional induced crystallization synchronous removal of fluoride, calcium, magnesium and silicon ions in wastewater by pellet according to claim 9, characterized in that, The proportion of Se powder, dimethyl formamide and NaBH4 in solution A is (0.6-1.0) g:(60-100) mL:(0.2-0.5) g; The proportion of Na2WO4 and deionized water in solution B is (1.3-1.8) g:(10-30) mL; The volume ratio of solution B to solution A is (10-30):(60-100); The temperature of heating and preservation is 220-230℃; The concentration of NaOH solution is 1.0-1.5 mol / L.

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