Composite polymeric ferric sulfate and production method thereof

Abstract

The invention relates to the technical field of polymeric ferric sulfate, and discloses composite polymeric ferric sulfate and a production method thereof.The production method comprises the following steps that S1, a titanium dioxide by-product ferrous sulfate is taken and prepared into a ferrous sulfate solution; s2, adding sulfuric acid and hydrochloric acid into the ferrous sulfate solution, adding a phosphorus source, uniformly stirring, and adding hydrogen peroxide for reaction to generate polymeric phosphorus ferric sulfate; adding silicic acid and the modified graphene into the polymeric ferric sulfate, placing in an ultrasonic environment, and curing to obtain the composite polymeric ferric sulfate, the content of iron in the composite polymeric ferric sulfate is 9.5-12.5%, the content of sulfate ions is 5-7.8%, and the content of the modified graphene is 2.5-5.5% in percentage by mass. The composite polymeric ferric sulfate is subjected to phosphorus and silicon modification treatment, and modified graphene is introduced, so that the problem that the polymeric ferric sulfate coagulant is easy to separate out a solid phase, namely, the stability is poor, as the use time goes on can be effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of polyferric sulfate, and in particular, to a composite polyferric sulfate and a production method thereof. Background Art

[0002] Common inorganic coagulants are mainly divided into traditional aluminum salts or iron salts, and polymer coagulants developed on the basis of traditional aluminum salts or iron salts, such as polyferric sulfate, polyferric chloride, polyaluminum sulfate, polyaluminum chloride, etc. Compared with traditional aluminum salts or iron salts, polymer coagulants have more prominent water purification effects, and are cheaper than organic polymer coagulants. Therefore, they have gradually replaced traditional coagulants or organic polymer coagulants and become the current mainstream coagulants.

[0003] Among them, polyaluminum ferric sulfate chloride, polyaluminum ferric chloride, polyaluminum ferric sulfate, etc. are all polymer coagulants mainly based on aluminum salts and supplemented by iron salts. Since the residual Al in water 3+ will bring certain toxic and side effects to the environment and is not conducive to long-term sustainable application and development, it has attracted wide attention. Polyferric coagulants have excellent coagulation performance, form large and dense flocs, have a fast sedimentation speed, a wide applicable range of pH values and water temperatures, and have good removal effects on COD, BOD, chromaticity and heavy metals in various wastewaters, and have no toxic and side effects on the environment. Therefore, they have become the research focus of current inorganic polymer coagulants.

[0004] For example, the patent with the publication number CN115959756A provides a modified polyferric sulfate and a preparation method thereof. By weight, the modified polyferric sulfate includes the following raw materials: 40-60 parts of pyrite cinder, 15-25 parts of sulfuric acid, 1-5 parts of oxidant, 1-10 parts of acetic acid, 10-20 parts of sodium carboxymethyl cellulose and 1-5 parts of stabilizer, which has a good removal efficiency and effect on pollutants, and enables it to have a good basicity, decolorization rate and COD removal rate.

[0005] However, when operators use the existing polyferric sulfate for water treatment, it is found that over time, the polyferric sulfate coagulant is prone to precipitate solid substances, and there is a problem of poor stability; and after working for a period of time, the equipment is corroded more obviously, backmixing is likely to occur in the water, and there are obvious peculiar smells such as rust, that is, the actual industrial water treatment effect is poor. Summary of the Invention

[0006] The technical problems to be solved by the present invention:

[0007] In practical applications, it is found that when the existing polyferric sulfate is used for water treatment, with the passage of time, the polyferric sulfate coagulant is prone to precipitate solid substances, and there is a problem of poor stability; and after working for a period of time, the equipment is significantly corroded, and phenomena such as backmixing are likely to occur in the water, and there are obvious peculiar smells such as rust, that is, the water treatment effect of actual industrialization is poor.

[0008] The technical solution adopted by the present invention:

[0009] The present invention provides a production method of composite polyferric sulfate, comprising the following steps:

[0010] S1 Take the by-product ferrous sulfate of titanium dioxide and prepare it into a ferrous sulfate solution;

[0011] S2 Add sulfuric acid and hydrochloric acid to the ferrous sulfate solution, then add a phosphorus source, stir well, add hydrogen peroxide for reaction to generate polyphosphorus ferric sulfate; then add silicic acid and modified graphene to the polyphosphorus ferric sulfate, place it in an ultrasonic environment, and ripen to obtain the composite polyferric sulfate.

[0012] Preferably, in step S1, the concentration of ferrous sulfate is 135-180 g / L; in step S2, the pH value of the slurry after adding sulfuric acid and hydrochloric acid is controlled to be 3-5.

[0013] Preferably, in step S2, using ferrous sulfate solution, concentrated sulfuric acid and hydrochloric acid as reaction raw materials, the addition amount of the phosphorus source is controlled so that the phosphorus-iron ratio is 1-1.3:1, the addition amount of silicic acid is 3.5-5 times the total mass of the reaction raw materials, and the addition amount of modified graphene is 2.5-8% of the total mass of the reaction raw materials.

[0014] Preferably, in step S2, the preparation method of the modified graphene is as follows:

[0015] Take graphene oxide, place it in ethanol, and disperse it ultrasonically to obtain a graphene dispersion; separately take vinyl POSS and hydrogen peroxide, add them to the graphene dispersion, and under stirring, heat and react, and dry after cooling to obtain the modified graphene.

[0016] Preferably, during the heating reaction process, first heat to 120-150 °C and preheat for 20-40 min, then raise the temperature to 180-250 °C and react for 1-3 h.

[0017] Preferably, during cooling, the cooling rate is controlled to be 5-20 °C / min.

[0018] Preferably, by mass, the dosage ratio of graphene oxide to vinyl POSS is 1-3:1, and the dosage of hydrogen peroxide is 0.5-5 wt% of the total mass of graphene oxide and vinyl POSS.

[0019] In the composite polyferric sulfate of the present invention, by mass fraction, the iron content is 9.5 - 12.5%, the sulfate ion content is 3 - 5.8%, and the content of modified graphene is 2.5 - 5.5%.

[0020] The beneficial effects of the present invention are as follows:

[0021] Through research, it is found that when using a single iron salt as a coagulant in the present invention, during the use process, it is easy to cause corrosion to equipment. Due to the influence of ferrous ions, when the dosage is large, phenomena such as backmixing are likely to occur. In addition, the water treated with a single iron salt has an obvious rust smell, which will cause discomfort in terms of sensory perception. Based on this, the present invention proposes a composite polyferric sulfate modified by silicon and phosphorus. When used as a coagulant, it can alleviate the problems that occur when using the above single iron salt.

[0022] Specifically, in the preparation process of the composite polyferric sulfate of the present invention, the introduction of metal ions such as magnesium, sodium, or aluminum is avoided, which can reduce the continuous reaction of the composite polyferric sulfate with other impurity metal ions during the use process to form solid precipitates, thereby maintaining the stability of the composite polyferric sulfate; using hydrochloric acid to replace part of sulfuric acid can effectively improve the stability of polyferric sulfate; by reducing the concentration of certain reaction raw materials, the generation of solid precipitates such as MgFe4(SO4)6(OH)2·20H2O can be blocked, avoiding chemical deterioration of the composite polyferric sulfate from the source. And during the polymerization reaction, introducing phosphorus and silicon elements and adding modified graphene can effectively enhance the adsorption capacity of the composite polyferric sulfate as a water treatment additive, thereby improving its treatment effect and also avoiding the influence on the adsorption and flocculation effects due to the reduction of the raw material concentration. Description of the Drawings

[0023] Figure 1 XRD analysis spectrum of the yellow solid phase precipitate in Comparative Example 1. Detailed Embodiments

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Those not specified in the embodiments are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or instruments not specified in the manufacturer are all conventional products that can be obtained through commercial purchase.

[0025] The present invention provides a composite polyferric sulfate, and its production method includes the following steps:

[0026] Using the by-product ferrous sulfate from the preparation of titanium dioxide as the raw material, dissolve it in deionized water to prepare a ferrous sulfate solution with a concentration of about 135 - 180 g / L; add concentrated sulfuric acid and hydrochloric acid to the ferrous sulfate solution, where the mass of sulfuric acid is 1.5 - 2 times that of ferrous sulfate, adjust the pH value to 3 - 5, then add a phosphorus source, stir evenly, and then add hydrogen peroxide, stir and react to carry out a series of reactions such as oxidation, hydrolysis and polymerization to generate polyphosphoric acid ferric sulfate; then add silicic acid and modified graphene to the polyphosphoric acid ferric sulfate, place it in an ultrasonic environment, and carry out aging for 5 - 30 min to obtain composite polyferric sulfate;

[0027] Among them, the ferrous sulfate solution, concentrated sulfuric acid and hydrochloric acid are used as reaction raw materials. The addition amount of the phosphorus source is controlled so that the phosphorus - iron molar ratio is 1 - 1.3:1. The addition amount of silicic acid is 3.5 - 5 times the total mass of the reaction raw materials, and the addition amount of modified graphene is 2.5 - 8% of the total mass of the reaction raw materials.

[0028] In the present invention, the preparation method of modified graphene includes the following steps:

[0029] Take graphene oxide, place it in ethanol, and perform ultrasonic treatment to form a graphene dispersion; separately take vinyl POSS and hydrogen peroxide, add them to the graphene dispersion, under stirring, heat to 120 - 150 °C for preheating for 20 - 40 min, then raise the temperature to 180 - 250 °C, continue to react for 1 - 3 h, and slowly cool at a cooling rate of 5 - 20 °C / min, and dry to obtain modified graphene;

[0030] Among them, by mass, the dosage ratio of graphene oxide to vinyl POSS is 1 - 3:1, and the dosage of hydrogen peroxide is 0.5 - 5 wt% of the total mass of graphene oxide and vinyl POSS.

[0031] In the preparation process of the composite polyferric sulfate of the present invention, it can avoid introducing other ions other than H + 、Fe 3+ 、SO4 2 -、OH - to a greater extent. Furthermore, it can reduce the precipitation caused by the further reaction of other metal ions with the polyferric sulfate product. That is, the composite polyferric sulfate in the present invention can maintain the stability of substances and properties for a longer time during the water treatment process.

[0032] In the composite polyferric sulfate of the present invention, by mass fraction, the iron content is 9.5 - 12.5%, the sulfate ion content is 5 - 7.8%, and the modified graphene content is 2.5 - 5.5%.

[0033] Example 1

[0034] Step 1: Take about 150.3 g of the by-product ferrous sulfate from titanium dioxide production, place it in 1 L of deionized water, and prepare a ferrous sulfate solution with a concentration of 150.3 g / L. Then, add an equal volume of 98% concentrated sulfuric acid and 1 M hydrochloric acid to the ferrous sulfate solution, and control the total mass of sulfuric acid and hydrochloric acid to be 1.6 times the mass of ferrous sulfate. At this time, measure the pH value of the slurry to be 4.7, which meets the standard of the reaction conditions, and it can be used as the reaction stock solution for standby.

[0035] Step 2: Add phosphoric acid to the reaction stock solution, and the molar amount of phosphoric acid is 1.2 times that of ferric ions. After stirring evenly, add an equal volume of hydrogen peroxide, and stir at 120 rpm for 1 h to enable the above raw materials to undergo a series of complex reactions to form polyphosphoric acid ferric sulfate.

[0036] Step 3: Add metasilicic acid and modified graphene to the polyphosphoric acid ferric sulfate. The dosage of metasilicic acid is 4.2 times the total mass of the reaction stock solution, and the addition amount of modified graphene is 3.6 wt% of the reaction stock solution. After mixing, place it in an ultrasonic environment and ripen for 15 min to obtain the composite polyferric sulfate.

[0037] The composite polyferric sulfate prepared in this example has a polyferric concentration of 10.5 wt%, and the concentrations of magnesium and sodium are both lower than 2.0 wt%, and both are inevitable impurities from the raw material titanium dioxide by-product.

[0038] Example 2

[0039] Step 1: Take about 151.9 g of the by-product ferrous sulfate from titanium dioxide production, place it in 1 L of deionized water, and prepare a ferrous sulfate solution with a concentration of 151.9 g / L. Then, add an equal volume of 98% concentrated sulfuric acid and 1 M hydrochloric acid to the ferrous sulfate solution, and control the total mass of sulfuric acid and hydrochloric acid to be 1.85 times the mass of ferrous sulfate. At this time, measure the pH value of the slurry to be 3.9, which meets the standard of the reaction conditions, and it can be used as the reaction stock solution for standby.

[0040] Step 2: Add phosphoric acid to the reaction stock solution, and the molar amount of phosphoric acid is 1.27 times that of ferric ions. After stirring evenly, add an equal volume of hydrogen peroxide, and stir at 120 rpm for 1 h to enable the above raw materials to undergo a series of complex reactions to form polyphosphoric acid ferric sulfate.

[0041] Step 3: Add metasilicic acid and modified graphene to the polyphosphoric acid ferric sulfate. The dosage of metasilicic acid is 4.2 times the total mass of the reaction stock solution, and the addition amount of modified graphene is 3.2 wt% of the reaction stock solution. After mixing, place it in an ultrasonic environment and ripen for 15 min to obtain the composite polyferric sulfate.

[0042] The composite polyferric sulfate prepared in this example has a polyferric concentration of 11.33 wt%, and the concentrations of magnesium and sodium are both lower than 2.0 wt%, and both come from the inevitable impurities in the raw material titanium dioxide by-product.

[0043] Example 3

[0044] Step 1: Take about 152.0 g of the by-product ferrous sulfate from the preparation of titanium dioxide, place it in 1 L of deionized water, and prepare a ferrous sulfate solution with a concentration of 152.0 g / L; then add 98% concentrated sulfuric acid and 1 M hydrochloric acid with the same volume to the ferrous sulfate solution, and control the total mass of sulfuric acid and hydrochloric acid to be 2 times the mass of ferrous sulfate. At this time, measure the pH value of the slurry to be 3.4, which meets the standard of the reaction conditions, and it can be used as the reaction stock solution for standby.

[0045] Step 2: Add phosphoric acid to the reaction stock solution, and the molar amount of phosphoric acid is 1 times that of ferric ions. After stirring evenly, add hydrogen peroxide with the same volume, and stir at 10 rpm for 1 h to make the above raw materials undergo a series of complex reactions to form polyphosphoric acid ferric sulfate.

[0046] Step 3: Add metasilicic acid and modified graphene to the polyphosphoric acid ferric sulfate. The dosage of metasilicic acid is 4.2 times the total mass of the reaction stock solution, and the addition amount of modified graphene is 2.9 wt% of the reaction stock solution; after mixing, place it in an ultrasonic environment and ripen for 15 min to obtain the composite polyferric sulfate.

[0047] The composite polyferric sulfate prepared in this example has a polyferric concentration of 11.02 wt%, and the concentrations of magnesium and sodium are both lower than 2.0 wt%, and both come from the inevitable impurities in the raw material titanium dioxide by-product.

[0048] Comparative Example 1

[0049] Step 1: Take about 150.5 g of the by-product ferrous sulfate from the preparation of titanium dioxide, place it in 1 L of deionized water, and prepare a ferrous sulfate solution with a concentration of 150.5 g / L; then add magnesium sulfate to the ferrous sulfate solution, and control the mass of magnesium sulfate to be 1.2 times the mass of ferrous sulfate. At this time, measure the pH value of the slurry to be 3.1, which meets the standard of the reaction conditions, and it can be used as the reaction stock solution for standby.

[0050] Step 2: Add sodium chloride with the same volume to the reaction stock solution, and stir at 120 rpm for 1 h to make the above raw materials undergo a series of complex reactions to form polyferric sulfate.

[0051] The composite polyferric sulfate prepared in this example has a polyferric concentration of 18.06 wt%, a magnesium concentration of 11.31 wt%, and a sodium concentration of 11.58 wt%.

[0052] Test Example

[0053] Samples: Examples 1 - 3, Comparative Example 1

[0054] (1) Stability Observation

[0055] Take the polyferric sulfate products prepared in Examples 1 to 3 and Comparative Example 1 as samples, place them all in a storage bag, and let them stand for 30 days. Then observe the morphological changes of the samples before and after placement. It is found through observation that the morphology of the composite polyferric sulfate in Examples 1 to 3 is basically the same before and after placement, while for the sample in Comparative Example 1, obvious yellow solid precipitates are produced after placement compared with before placement. Therefore, it can be shown that the composite polyferric sulfate in Examples 1 to 3 has stronger stability.

[0056] (2) Solid Phase Analysis

[0057] Use the polyferric salt sample prepared in Comparative Example 1 to measure the content relationship of substances therein, and the results are summarized in Table 2 below:

[0058] Table 2 Measurement Results of Substance Content Relationship in Comparative Example 1

[0059] specimen magnesium-iron molar ratio iron content (%) basicity (%) Comparative Example 1 0.15 18.06 10.92

[0060] Let the above samples stand for 30 days, and then it is observed that obvious yellow solid phases precipitate out. Wash the solid phases with ethanol, then dry them, and perform X-ray diffraction analysis. The XRD analysis pattern of the solid phases is as Figure 1 shown. It can be obtained from Figure 1 that the main component of the solid phase is MgFe4(SO4)6(OH)2·20H2O.

[0061] Through the above analysis, it can be demonstrated that the appearance of solid phases in the traditional polyferric salt coagulant during use is due to the magnesium element contained in the raw materials. And in the present invention, by using phosphorus and silicon for modification treatment and introducing modified graphene, it can not only reduce problems such as the oxidation of iron salts in the water environment, but also help maintain the stability of the polyferric salt coagulant. Combining with the control of the dosage of each elemental substance and environmental conditions, the physical properties of the polyferric salt are further stabilized, enabling it to be applied to the water treatment process in a long-term and stable manner.

[0062] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, various changes and modifications can be made to the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A production method of composite polyferric sulfate, characterized in that It includes the following steps: S1: Take the by-product ferrous sulfate of titanium dioxide and prepare it into a ferrous sulfate solution; S2: Add sulfuric acid and hydrochloric acid to the ferrous sulfate solution, then add a phosphorus source, stir well, add hydrogen peroxide for reaction to generate polyphosphoric acid ferric sulfate; then add silicic acid and modified graphene to the polyphosphoric acid ferric sulfate, place it in an ultrasonic environment, and age to obtain the composite polyferric sulfate.

2. The production method of the composite polyferric sulfate according to claim 1, characterized in that, In step S1, the concentration of ferrous sulfate is 135 - 180 g / L; in step S2, the pH value of the slurry after adding sulfuric acid and hydrochloric acid is controlled to be 3 - 5.

3. The production method of the composite polyferric sulfate according to claim 1, characterized in that, In step S2, using the ferrous sulfate solution, concentrated sulfuric acid and hydrochloric acid as reaction raw materials, the addition amount of the phosphorus source is controlled such that the phosphorus-iron ratio is 1 - 1.3:1, the addition amount of silicic acid is 3.5 - 5 times the total mass of the reaction raw materials, and the addition amount of modified graphene is 2.5 - 8% of the total mass of the reaction raw materials.

4. The production method of the composite polyferric sulfate according to any one of claims 1 to 3, characterized in that, In step S2, the preparation method of the modified graphene is as follows: Take graphene oxide, place it in ethanol, and disperse it by ultrasonic to obtain a graphene dispersion; separately take vinyl POSS and hydrogen peroxide, add them to the graphene dispersion, heat and react under stirring, and dry after cooling to obtain the modified graphene.

5. The production method of the composite polymeric ferric sulfate according to claim 4, characterized in that, During the heating reaction process, first heat to 120 - 150 °C and preheat for 20 - 40 min, then raise the temperature to 180 - 250 °C and react for 1 - 3 h.

6. The production method of the composite polyferric sulfate according to claim 4, characterized in that, When cooling, control the cooling rate to be 5 - 20 °C / min.

7. The production method of the composite polymeric ferric sulfate according to claim 4, characterized in that, By mass, the dosage ratio of graphene oxide to vinyl POSS is 1 - 3:1, and the dosage of hydrogen peroxide is 0.5 - 5 wt% of the total mass of graphene oxide and vinyl POSS.

8. The composite polymeric ferric sulfate prepared by the production method according to any one of claims 1 to 7, characterized in that, By mass fraction, the iron content is 9.5 - 12.5%, the sulfate ion content is 3 - 5.8%, and the modified graphene content is 2.5 - 5.5%.

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