CN115814750B - Method for preparing porous calcium silicate adsorbent from phosphogypsum - Google Patents
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Abstract
The invention discloses a method for preparing a porous calcium silicate adsorbent from phosphogypsum, and belongs to the technical field of gypsum recycling. Mainly comprises the following steps: mixing phosphogypsum, a silicon source, caustic alkali and water, uniformly stirring, and reacting under a closed condition to obtain filtrate and a solid product. And (3) drying the solid product, and then, adsorbing and enriching phosphorus in the phosphorus-containing wastewater, wherein after the adsorption is finished, the solid product can be converted into the calcium-silicon-phosphorus compound fertilizer. The filtrate is further purified, and sulfate in the filtrate can be recovered. The invention fully utilizes the resources of calcium, sulfur, phosphorus and the like in the phosphogypsum, realizes the recycling of the phosphogypsum and the phosphorus-containing wastewater, and has important significance for the high-value utilization of solid waste and wastewater.
Description
Technical Field
The invention belongs to the technical field of gypsum recycling recovery, and particularly relates to a method for preparing a porous calcium silicate adsorbent from phosphogypsum.
Background
The main component of the solid waste generated in the phosphogypsum wet-process phosphoric acid process is calcium sulfate dihydrate, which accounts for more than 90% of the total amount. Phosphogypsum produced in China is about 6000-8000 ten thousand tons per year, and accounts for about 40% of the total world. Because phosphogypsum still contains a small amount of components such as phosphorus, fluorine and organic matters, the hardening strength and the setting time of phosphogypsum products are seriously influenced, the utilization of phosphogypsum is limited, and most phosphogypsum is still piled up mainly in a piling plant at present. The phosphorus-containing wastewater mostly occurs in links of exploitation and smelting of phosphorite, domestic sewage and agricultural wastewater, the phosphorus content in the wastewater is low, the pH distribution is wide, the wastewater is difficult to effectively recycle and utilize, and the adsorption method is one of the most promising cheap extraction schemes.
Most of the research at present is focused on removing phosphorus in phosphogypsum, and people notice that phosphorus is a nutrient element necessary for crop growth, if phosphogypsum can be converted into fertilizer, adverse effects of phosphorus in phosphogypsum can be eliminated, waste can be changed into valuable, and phosphorus element needed by crops is supplemented.
Disclosure of Invention
In view of the above, the invention provides a method for preparing a porous calcium silicate adsorbent by phosphogypsum, which uses phosphogypsum as a raw material to prepare a cheap adsorbent for adsorbing and enriching phosphorus in wastewater, and converts the phosphorus into a calcium-silicon-phosphorus compound fertilizer, so that waste materials can be changed into valuable materials, and two problems of phosphogypsum solid waste and phosphorus-containing wastewater can be synchronously solved.
In order to achieve the above purpose, the present invention proposes the following technical solutions:
the technical scheme is as follows: a porous calcium silicate adsorbent is prepared from phosphogypsum, a silicon source, caustic alkali and water through reaction, wherein the molar ratio of calcium to silicon in the system is 0.8-3.0, the molar ratio of sodium/potassium to silicon is 1.0-2.0, and the solid-liquid ratio of phosphogypsum to water is 1g (4-50) mL.
Further, the silicon source is sodium/potassium water glass, silicic acid or silicon-containing waste; the caustic alkali is sodium hydroxide or potassium hydroxide.
The second technical scheme is as follows: a method for preparing a porous calcium silicate adsorbent, comprising the following steps: mixing phosphogypsum, a silicon source, caustic alkali and water, uniformly stirring, reacting under a closed condition to obtain filtrate and a solid product, and drying the obtained solid product to obtain the porous calcium silicate adsorbent.
Further, the reaction temperature is between room temperature and 250 ℃ and the reaction time is between 0.5 and 48 hours.
The technical scheme is as follows: the application of porous calcium silicate adsorbent in treating phosphorus-containing waste water.
Further, the phosphorus-containing wastewater comprises wastewater generated in the phosphorite exploitation and smelting process, domestic wastewater or agricultural wastewater.
The technical scheme is as follows: the application of porous calcium silicate adsorbent as fertilizer is that the porous calcium silicate adsorbent is placed in phosphorus-containing waste water to adsorb phosphorus, and after the adsorption is completed, the calcium-silicon-phosphorus compound fertilizer is obtained.
The fifth technical scheme is that: a magnetic porous calcium silicate adsorbent is prepared by adding ferroferric oxide based on phosphogypsum, silicon source, caustic alkali and water as raw materials for reaction, wherein the mass ratio of ferroferric oxide to phosphogypsum in the system is (0.1-2): 1. The reaction temperature is between room temperature and 250 ℃ and the reaction time is between 0.5 and 48 hours.
The sixth technical scheme is as follows: a preparation method of a magnetic porous calcium silicate adsorbent comprises the following steps: mixing phosphogypsum, a silicon source, caustic alkali, ferroferric oxide and water, uniformly stirring, reacting under a closed condition to obtain filtrate and a solid product, and drying the obtained solid product to obtain the magnetic porous calcium silicate adsorbent.
The technical proposal is that: use of a magnetic porous calcium silicate adsorbent in treating phosphorus-containing wastewater. The phosphorus-containing wastewater comprises wastewater generated in the phosphorite exploitation and smelting process, domestic sewage or agricultural wastewater.
Eighth technical scheme: the application of the magnetic porous calcium silicate adsorbent as fertilizer is that the magnetic porous calcium silicate adsorbent is placed in phosphorus-containing wastewater to adsorb phosphorus, and after the adsorption is finished, the magnetic calcium silicon phosphorus compound fertilizer is obtained.
Technical scheme nine: the sulfate is prepared by purifying filtrate prepared by the preparation methods of the porous calcium silicate adsorbent and the porous magnetic calcium silicate adsorbent.
Compared with the prior art, the invention has the beneficial effects that:
the method is simple to operate, the phosphogypsum used in the method does not need washing or piling pretreatment, the phosphogypsum can be directly used for production, the equipment requirement is low, and the two pollution problems of phosphogypsum solid waste and phosphorus-containing wastewater can be synchronously solved. In addition, sulfate in the catalyst can be recovered, so that the economic advantage is further enlarged.
The invention takes phosphogypsum as an inexpensive calcium source, prepares the porous calcium silicate adsorbent through one-step double decomposition reaction, then adsorbs and enriches phosphorus in the phosphorus-containing wastewater, and finally converts the phosphorus-rich wastewater into the calcium-silicon-phosphorus compound fertilizer. Sulphate remaining in the filtrate by CO 2 Removing impurities, crystallizing and separating to obtain sulfate products (more than 99%) with higher purity for recovery. The method is simple to operate, and can realize large-scale digestion and high-value utilization of phosphogypsum, and meanwhile, the sulfate product with higher byproduct value and wide application range is obtained. In the preparation process, fe is added 3 O 4 The method can be used for preparing the magnetic porous calcium silicate adsorbent, further preparing the magnetic calcium silicon phosphorus compound fertilizer and has wider application range.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a graph of the microscopic morphology of the porous calcium silicate adsorbent prepared in example 1 of the present invention;
FIG. 2 is a graph showing the change in adsorption performance of the porous calcium silicate adsorbent prepared in example 1 of the present invention to phosphate at different pH values;
fig. 3 shows the total and effective contents of calcium, silicon and phosphorus after saturation of phosphate adsorption by the porous calcium silicate adsorbent prepared in example 1 of the present invention at ph=3;
FIG. 4 is a graph showing the change in adsorption performance of the porous calcium silicate adsorbents prepared in examples 1 to 7 according to the present invention to phosphate;
FIG. 5 is a graph showing the change in adsorption performance of the porous calcium silicate adsorbents prepared in examples 8 to 16 according to the present invention on phosphate;
FIG. 6 is a diagram of the microscopic morphology of the ferroferric oxide prepared in accordance with the present invention;
FIG. 7 is a graph showing the change in adsorption performance of the magnetic porous calcium silicate adsorbents prepared in examples 17 to 21 according to the present invention to phosphate.
Detailed Description
Various exemplary embodiments of the invention will now be described in detail, which should not be considered as limiting the invention, but rather as more detailed descriptions of certain aspects, features and embodiments of the invention.
It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In addition, for numerical ranges in this disclosure, it is understood that each intermediate value between the upper and lower limits of the ranges is also specifically disclosed. Every smaller range between any stated value or stated range, and any other stated value or intermediate value within the stated range, is also encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.
It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the invention described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from consideration of the specification of the present invention. The specification and examples are exemplary only.
As used herein, the terms "comprising," "including," "having," "containing," and the like are intended to be inclusive and mean an inclusion, but not limited to.
The term "room temperature" as used herein means 25℃unless otherwise specified.
The porous calcium silicate prepared by the invention is a green adsorbent which is simple to prepare, high in adsorption capacity, nontoxic, harmless and easy to recycle, phosphogypsum is used as a cheap calcium source, and the porous calcium silicate adsorbent which is low in cost and high in adsorption performance is prepared by a simple double decomposition method and is used for adsorbing and enriching phosphorus in phosphorus-containing wastewater, and after the adsorption is completed, the adsorbent is converted into a calcium-silicon-phosphorus compound fertilizer which can be used for crop production. Not only can eliminate the damage of phosphogypsum and phosphorus-containing wastewater to the environment, but also can realize the large-scale digestion and high-value utilization of phosphogypsum.
Addition of Fe during the preparation of the adsorbent 3 O 4 Can be used for preparing phosphogypsum-based Fe 3 O 4 The porous calcium silicate composite adsorbent is easier to recycle in the adsorption process, has more abundant application scenes, can be converted into a magnetic calcium silicon phosphorus compound fertilizer after the adsorption is finished, and is more beneficial to the yield increase of crops.
The specific technical scheme is as follows:
the technical scheme is as follows: a porous calcium silicate adsorbent is prepared by reacting phosphogypsum, a silicon source, caustic alkali and water, wherein the molar ratio of calcium to silicon in the system is 0.8-2.0, more preferably 0.8, 1.0, 1.1, 1.2, 1.5 and 2.0; the molar ratio of sodium/potassium to silicon is 1.0-2.0, more preferably 1.0, 1.2; the solid-to-liquid ratio of phosphogypsum to water is 1g (4-50 mL), more preferably 1g:20mL, 1g:15mL.
In some preferred embodiments, the silicon source is sodium/potassium water glass, silicic acid or silicon-containing waste, more preferably sodium water glass, silicic acid; the caustic is sodium hydroxide or potassium hydroxide, more preferably sodium hydroxide.
The second technical scheme is as follows: a method for preparing a porous calcium silicate adsorbent, comprising the following steps: mixing phosphogypsum, a silicon source, caustic alkali and water, uniformly stirring, reacting under a closed condition to obtain filtrate and a solid product, and drying the obtained solid product to obtain the porous calcium silicate adsorbent.
In some preferred embodiments, the reaction temperature is from room temperature to 250 ℃, more preferably 40 ℃,60 ℃, 80 ℃,90 ℃,100 ℃, 120 ℃, 140 ℃, 160 ℃, 180 ℃, 200 ℃; the reaction time is 0.5 to 48 hours, more preferably 5 hours and 6 hours.
The technical scheme is as follows: the application of porous calcium silicate adsorbent in treating phosphorus-containing waste water.
In some preferred embodiments, the phosphorus-containing wastewater includes wastewater produced during exploitation and smelting of phosphorus ore, domestic sewage, or agricultural wastewater.
The technical scheme is as follows: the application of porous calcium silicate adsorbent as fertilizer is that the porous calcium silicate adsorbent is placed in phosphorus-containing waste water to adsorb phosphorus, and after the adsorption is completed, the calcium-silicon-phosphorus compound fertilizer is obtained.
The fifth technical scheme is that: a magnetic porous calcium silicate adsorbent is obtained by adding ferroferric oxide to the raw materials of phosphogypsum, silicon source, caustic alkali and water for reaction, wherein the mass ratio of the ferroferric oxide to the phosphogypsum in the system is (0.1-2): 1, more preferably 0.1:1, 0.2:1, 0.5:1, 1:1 and 2:1.
The sixth technical scheme is as follows: a preparation method of a magnetic porous calcium silicate adsorbent comprises the following steps: mixing phosphogypsum, a silicon source, caustic alkali, ferroferric oxide and water, uniformly stirring, reacting under a closed condition to obtain filtrate and a solid product, and drying the obtained solid product to obtain the magnetic porous calcium silicate adsorbent. The reaction temperature is room temperature to 250 ℃, more preferably 60 ℃, and the reaction time is 0.5 to 48h, more preferably 6h.
The technical proposal is that: use of a magnetic porous calcium silicate adsorbent in treating phosphorus-containing wastewater. The phosphorus-containing wastewater comprises wastewater generated in the phosphorite exploitation and smelting process, domestic sewage or agricultural wastewater.
Eighth technical scheme: the application of the magnetic porous calcium silicate adsorbent as fertilizer is that the magnetic porous calcium silicate adsorbent is placed in phosphorus-containing wastewater to adsorb phosphorus, and after the adsorption is finished, the magnetic calcium silicon phosphorus compound fertilizer is obtained.
Technical scheme nine: the sulfate is prepared by purifying filtrate prepared by the preparation methods of the porous calcium silicate adsorbent and the porous magnetic calcium silicate adsorbent. A small amount of silicon and calcium still remain in the filtrate, and carbon dioxide is required to be introduced to precipitate the calcium and the silicon in the form of calcium carbonate and silicon dioxide respectively, so as to obtain purified sulfate.
The following examples serve as further illustrations of the technical solutions of the invention.
Example 1
Phosphogypsum used in this example was taken from a certain phosphogypsum yard in Henan, and piled up for about 1 year, dried to constant weight at 80 ℃ before use, and chemical components therein were analyzed by XRF, and the results are shown in Table 1.
Table 1 main chemical composition (wt.%) in phosphogypsum
| SO 3 | CaO | SiO 2 | P 2 O 5 | Al 2 O 3 | MgO | Fe 2 O 3 | K 2 O | Others |
| 50.80 | 38.41 | 6.15 | 1.93 | 0.83 | 0.73 | 0.54 | 0.31 | 0.30 |
1. A preparation method of a porous calcium silicate adsorbent comprises the following steps:
1) 10 g of phosphogypsum raw material is weighed, and sodium silicate and sodium hydroxide with certain mass are added so that the molar ratio of Ca to Si is 1.0 and the molar ratio of Na to Si is 1.2.
2) 200mL of distilled water was added and stirring was continued with a magnetic stirrer for 2 hours to allow the raw materials to mix well. And transferring the uniformly mixed raw materials into a closed reaction kettle, continuously reacting for 6 hours at 90 ℃, and taking out and filtering after the temperature is reduced to room temperature. And collecting filtrate and solid products, and drying the solid products to obtain the porous calcium silicate adsorbent.
2. A method for preparing a calcium-silicon-phosphorus compound fertilizer from phosphogypsum comprises the following steps:
the prepared porous calcium silicate adsorbent is used for treating phosphorus-containing wastewater generated in the phosphorite smelting process, and the phosphorus content is about 150mg/L. The pH value of the phosphorus-containing wastewater is adjusted to 2-11 by using 0.1mol/L hydrochloric acid and sodium hydroxide, and the influence of the initial concentration on the phosphorus adsorption capacity is studied. Filtering and drying after the adsorption is finished, thus obtaining the adsorbent which can be used as the calcium-silicon-phosphorus compound fertilizer. The contents of available phosphorus, silicon and calcium were analyzed.
3. A method for preparing sulfate:
collecting filtrate generated by the preparation method of the porous calcium silicate adsorbent, and introducing CO 2 Impurity removal is performed so that silicon and calcium remaining in the filtrate are converted into silicon dioxide and calcium carbonate, respectively, and impurity removal is performed by filtration. The filtrate after impurity removal is evaporated and crystallized, and a sodium sulfate product is recovered, and the components are analyzed by XRF, and the result is shown in table 2, wherein the content of sodium sulfate in the product reaches 99.48%.
Table 2 chemical analysis of sodium sulfate product (wt.%)
| SO 3 | Na 2 O | SiO 2 | K 2 O | CaO | Cl | Others |
| 52.57 | 46.91 | 0.24 | 0.17 | 0.06 | 0.03 | 0.02 |
The measurement method is as follows:
the addition amount of the porous calcium silicate adsorbent is 1.0g/L, and the phosphogypsum preparation is evaluated through a batch adsorption experimentThe adsorption and enrichment capacity of the porous calcium silicate adsorbent for phosphorus in the phosphorus ore smelting wastewater, and the microcosmic appearance of the porous calcium silicate adsorbent after the phosphorus-containing wastewater is treated is shown in figure 1. As can be seen from FIG. 1, phosphorus is mainly concentrated on the surface of the porous calcium silicate adsorbent due to spontaneous Ca release by the adsorbent in the phosphorus-containing wastewater 2+ And OH (OH) - Released Ca 2+ Is combined with phosphate radical in the solution and is attached to the surface of the adsorbent.
In step 3), the adsorption capacity of the porous calcium silicate adsorbent for phosphorus under different initial pH conditions is shown in FIG. 2. As can be seen from FIG. 2, the porous calcium silicate adsorbent prepared from phosphogypsum has strong adsorption capacity to phosphorus in a wide pH range (3-11), wherein the adsorption capacity is optimal at pH 3, because the acidic condition makes more use of the adsorbent to release Ca 2+ And OH (OH) - However, when the aqueous solution is more acidic (pH < 3), the tolerance of the porous calcium silicate is exceeded, calcium ions are leached out in a large amount, the porous structure is destroyed, and the adsorption effect on phosphorus is poor. The total and effective contents of calcium, silicon and phosphorus after saturation of the adsorbent were analyzed at an initial pH of 3.
At an initial pH of 3, the total and effective contents of calcium, silicon and phosphorus after saturation of the adsorbent adsorption are shown in FIG. 3. As can be seen from FIG. 3, the adsorbent after saturation contains high available calcium and available silicon (both greater than 30%), and has an available phosphorus content of > 20% (P 2 O 5 Calculated by the weight percentage), is an excellent calcium-silicon-phosphorus compound fertilizer.
Example 2
The porous calcium silicate adsorbent was prepared in the same manner as in example 1, except that the molar ratio of Ca to Si in the raw material of step 1) was 0.8.
Example 3
The porous calcium silicate adsorbent was prepared in the same manner as in example 1, except that the molar ratio of Ca to Si in the raw material of step 1) was 0.9.
Example 4
The porous calcium silicate adsorbent was prepared in the same manner as in example 1, except that the molar ratio of Ca to Si in the raw material of step 1) was 1.1.
Example 5
The porous calcium silicate adsorbent was prepared in the same manner as in example 1, except that the molar ratio of Ca to Si in the raw material of step 1) was 1.2.
Example 6
The porous calcium silicate adsorbent was prepared in the same manner as in example 1, except that the molar ratio of Ca to Si in the raw material of step 1) was 1.5.
Example 7
The porous calcium silicate adsorbent was prepared in the same manner as in example 1, except that the molar ratio of Ca to Si in the raw material of step 1) was 2.0.
The measurement method is as follows:
the porous calcium silicate prepared in examples 1-7 was used as an adsorbent for treating phosphorus-containing wastewater. The phosphorus-containing wastewater is prepared in a laboratory, the water used is the surface water of Guiyang urban Huaxi river, and PO is prepared by adding monopotassium sulfate 4 3- The concentration of P was 100mg/L and the initial pH of the phosphorus-containing wastewater was adjusted to 6 using 0.1M hydrochloric acid and NaOH. In the adsorption process, the addition amount of the adsorbent is 1.0g/L, the temperature is 25 ℃, and the adsorption time is set to 24 hours. The adsorption effect is shown in fig. 4.
As can be seen from fig. 4, the adsorption capacity of the synthesized porous calcium silicate to phosphorus is strong (removal is more than 90%) in a wide molar ratio range of calcium to silicon, and in a molar ratio range of 0.8 to 1.2, the adsorption capacity to phosphorus is stronger as the molar ratio of calcium to silicon increases, and the adsorption capacity to phosphorus starts to decrease as the molar ratio of calcium to silicon increases after the molar ratio of calcium to silicon is more than 1.2, because calcium sulfate in phosphogypsum cannot be completely converted into porous calcium silicate when the molar ratio is large, thereby reducing the adsorption capacity to phosphorus. This affects the available phosphorus content of the product after adsorption.
Example 8
Phosphogypsum used in this example was taken from fresh phosphogypsum in the phosphogypsum warehouse of Guizhou mountain, and dried to constant weight at 105 ℃ before use, and chemical components therein were analyzed by XRF, and the results are shown in Table 3. Fresh phosphogypsum contains higher P than phosphogypsum with long piling time (as in Table 1) 2 O 5 Is more favorable for being converted into the calcium-silicon-phosphorus compound fertilizer.
Table 3 main chemical composition (wt.%) in phosphogypsum
| SO 3 | CaO | SiO 2 | P 2 O 5 | Al 2 O 3 | Na 2 O | Fe 2 O 3 | K 2 O |
| 51.66 | 39.64 | 2.25 | 5.11 | 0.40 | 0.16 | 0.63 | 0.15 |
A preparation method of a porous calcium silicate adsorbent comprises the following steps:
1) 20 g of phosphogypsum raw material is weighed, and silicic acid and sodium hydroxide with certain mass are added so that the molar ratio of Ca to Si is 1.2 and the molar ratio of Na to Si is 1.0.
2) 300mL of distilled water was added and stirring was continued with a magnetic stirrer for 1h to allow the raw materials to mix well. And transferring the uniformly mixed raw materials into a closed reaction kettle, continuously reacting for 5 hours at 100 ℃, and taking out and filtering after the temperature is reduced to room temperature. And collecting filtrate and solid products, and drying the solid products to obtain the porous calcium silicate adsorbent.
Example 9
The porous calcium silicate adsorbent was prepared in the same manner as in example 8, except that the reaction temperature in step 2) was 40 ℃.
Example 10
The porous calcium silicate adsorbent was prepared in the same manner as in example 8, except that the reaction temperature in step 2) was 60 ℃.
Example 11
The porous calcium silicate adsorbent was prepared in the same manner as in example 8, except that the reaction temperature in step 2) was 80 ℃.
Example 12
The porous calcium silicate adsorbent was prepared in the same manner as in example 8, except that the reaction temperature in step 2) was 120 ℃.
Example 13
The porous calcium silicate adsorbent was prepared in the same manner as in example 8, except that the reaction temperature in step 2) was 140 ℃.
Example 14
The porous calcium silicate adsorbent was prepared in the same manner as in example 8, except that the reaction temperature in step 2) was 160 ℃.
Example 15
The porous calcium silicate adsorbent was prepared in the same manner as in example 8, except that the reaction temperature in step 2) was 180 ℃.
Example 16
The porous calcium silicate adsorbent was prepared in the same manner as in example 8, except that the reaction temperature in step 2) was 200 ℃.
The measurement method is as follows:
the porous calcium silicate prepared in examples 8-16 was used as an adsorbent for treating phosphorus-containing wastewater. The phosphorus-containing wastewater is prepared in a laboratory, and the water used is GuiyangSurface water of urban brook river is prepared into PO by adding monopotassium sulfate 4 3- The concentration of P was 200mg/L and the initial pH of the phosphorus-containing wastewater was adjusted to 8 using 0.1M hydrochloric acid and NaOH. In the adsorption process, the addition amount of the adsorbent is 1.5g/L, the temperature is 30 ℃, and the adsorption time is set to 24 hours. The adsorption effect is shown in fig. 5.
As can be seen from fig. 5, the adsorption capacity of the phosphogypsum synthesized adsorbent gradually decreases with the increase of the synthesis temperature, because the crystallinity of the adsorbent gradually increases with the increase of the synthesis temperature, and the release capacity of calcium ions and hydroxyl ions in the adsorbent gradually decreases, thereby decreasing the adsorption performance of the adsorbent. But the whole adsorption capacity is still quite considerable and is higher than 100mg/g.
Example 17
As a novel fertilizer, the magnetic fertilizer is a fertilizer combining a fertilizer and a magnetism. It is prepared from fertilizer (such as nitrogen, phosphorus, potassium, etc.) and magnetized magnetic carrier (such as powdered coal ash, pyrite cinder, etc.). The magnetic fertilizer can regulate the biological magnetic environment, so as to stimulate the growth of crops, activate the nutrient elements in soil and fertilizer, improve the nutrient absorption of crops, and increase the air permeability of soil, thereby achieving the aim of increasing the yield of plants.
Phosphogypsum used in this example is the same as that used in example 1, and the components are shown in Table 1.
A preparation method of a magnetic porous calcium silicate adsorbent comprises the following steps:
1) 10 g of phosphogypsum raw material is weighed, and sodium silicate, sodium hydroxide and ferroferric oxide suspension with certain mass are added so that the molar ratio of Ca to Si is 1.0, the molar ratio of Na to Si is 1.0, and the mass ratio of ferroferric oxide to phosphogypsum is 0.5:1.
The ferroferric oxide is prepared by a coprecipitation method in a laboratory, and the specific method comprises the following steps: 0.2mol of anhydrous ferric sulfate and 0.2mol of ferrous sulfate heptahydrate are weighed, dissolved in 1.5L of anaerobic water (boiled in advance for 5 minutes, then sealed and cooled to room temperature), and the solution is mechanically stirred. Preparing a sodium hydroxide solution with the concentration of 3mol/L, dropwise adding the sodium hydroxide solution to adjust the pH value of the solution to 9.5, continuously stirring in the dropwise adding process, introducing nitrogen for protection, and preventing oxidization, wherein the process lasts for about 1 hour. The reacted ferroferric oxide is attracted and gathered by a magnet, concentrated, washed by anaerobic water for a plurality of times, and finally 250mL of high-concentration ferroferric oxide suspension is prepared.
The microtopography is shown in FIG. 6. As can be seen from fig. 6, the prepared ferroferric oxide particles are uniform in size and are nano particles.
2) 200mL of distilled water was added and stirring was continued with a magnetic stirrer for 2 hours to allow the raw materials to mix well. And transferring the uniformly mixed raw materials into a closed reaction kettle, continuously reacting for 6 hours at 60 ℃, and taking out and filtering after the temperature is reduced to room temperature. And collecting filtrate and solid products, and drying the solid products to obtain the magnetic porous calcium silicate adsorbent.
Example 18
The preparation method of the magnetic porous calcium silicate adsorbent is the same as in example 17, except that the mass ratio of the ferroferric oxide to the phosphogypsum in the raw material in the step 1) is 0.1:1.
Example 19
The preparation method of the magnetic porous calcium silicate adsorbent is the same as in example 17, except that the mass ratio of the ferroferric oxide to the phosphogypsum in the raw material in the step 1) is 0.2:1.
Example 20
The preparation method of the magnetic porous calcium silicate adsorbent is the same as that of example 17, except that the mass ratio of the ferroferric oxide to the phosphogypsum in the raw material of step 1) is 1:1.
Example 21
The preparation method of the magnetic porous calcium silicate adsorbent is the same as in example 17, except that the mass ratio of the ferroferric oxide to the phosphogypsum in the raw material in step 1) is 2:1.
The measurement method is as follows:
the porous calcium silicate prepared in examples 17-21 was used as an adsorbent for treating phosphorus-containing wastewater. The phosphorus-containing wastewater is prepared in a laboratory, the water used is the surface water of Guiyang urban Huaxi river, and PO is prepared by adding monopotassium sulfate 4 3- The concentration of P was 100mg/L, and the initial pH of the phosphorus-containing wastewater was adjusted to 8 (near self-pH) using 0.1M hydrochloric acid and NaOHThe pH of the water). In the adsorption process, the addition amount of the adsorbent is 1.0g/L, the temperature is 25 ℃, and the adsorption time is set to 24 hours. The adsorption effect is shown in fig. 7.
As can be seen from fig. 7, as the amount of ferroferric oxide added gradually increases, the adsorption capacity of the prepared adsorbent gradually decreases, because the content of porous calcium silicate in the adsorbent gradually decreases due to the gradual increase of the content of ferroferric oxide.
The foregoing description of the preferred embodiments of the invention is not intended to limit the invention to the particular embodiments disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.
Claims (3)
1. The application of the porous calcium silicate adsorbent in treating the phosphorus-containing wastewater is characterized in that the concentration of the phosphorus-containing wastewater is 100mg/L, and 0.1M hydrochloric acid and NaOH are used for adjusting the initial pH value of the phosphorus-containing wastewater to 6; the addition amount of the adsorbent is 1.0g/L, the temperature is 25 ℃, and the adsorption time is 24 hours;
the porous calcium silicate adsorbent is prepared by taking phosphogypsum, a silicon source, caustic alkali and water as raw materials to react, wherein the molar ratio of calcium to silicon in a system is 1.0, the molar ratio of sodium/potassium to silicon is 1.2, and the solid-liquid ratio of phosphogypsum to water is 1g (4-50) mL;
the preparation method of the porous calcium silicate adsorbent comprises the following steps: mixing phosphogypsum, a silicon source, caustic alkali and water, uniformly stirring, reacting under a closed condition to obtain filtrate and a solid product, and drying the obtained solid product to obtain the porous calcium silicate adsorbent; the reaction temperature is 90 ℃ and the reaction time is 6h.
2. The use according to claim 1, wherein the silicon source is sodium/potassium water glass, silicic acid or silicon-containing waste; the caustic alkali is sodium hydroxide or potassium hydroxide.
3. The application of the magnetic porous calcium silicate adsorbent in the treatment of the phosphorus-containing wastewater is characterized in that the concentration of the phosphorus-containing wastewater is 100mg/L, and 0.1M hydrochloric acid and NaOH are used for adjusting the initial pH value of the phosphorus-containing wastewater to 8; the addition amount of the adsorbent is 1.0g/L, the temperature is 25 ℃, and the adsorption time is 24 hours;
the preparation method of the magnetic porous calcium silicate adsorbent comprises the following steps:
1) 10 g of phosphogypsum raw material is weighed, and sodium silicate, sodium hydroxide and ferroferric oxide suspension with certain mass are added so that the molar ratio of Ca to Si is 1.0, the molar ratio of Na to Si is 1.0, and the mass ratio of ferroferric oxide to phosphogypsum is 0.5:1;
2) Adding 200mL of distilled water, continuously stirring for 2 hours by using a magnetic stirrer to uniformly mix raw materials, transferring the uniformly mixed raw materials into a closed reaction kettle, continuously reacting for 6 hours at 60 ℃, taking out and filtering after the temperature is reduced to room temperature, collecting filtrate and solid products, and drying the solid products to obtain the magnetic porous calcium silicate adsorbent.
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| JP2007238412A (en) * | 2006-03-10 | 2007-09-20 | National Institute Of Advanced Industrial & Technology | Method for manufacturing calcium silicate secondary particle aggregate and its use |
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| CN108862206A (en) * | 2018-07-03 | 2018-11-23 | 贵州省贵福生态肥业有限公司 | The technique that a kind of ardealite and red mud prepare aluminium coproduction humic acid complex fertilizer |
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