A reducing scale inhibitor and its preparation method

Abstract

The present invention relates to a reducing scale inhibitor and a preparation method thereof, comprising the following components in mass percentages: thiourea dioxide 1-1.5%, sodium bisulfite or sodium metabisulfite 10-15%, urea 3-5%, sodium hexametaphosphate 10-20%, hydrolyzed maleic anhydride 8-10%, oxalic acid 5-10%, and the balance being water. The reducing scale inhibitor of the present invention can significantly reduce the ORP and residual chlorine in wastewater with only a small dosage, and at the same time has a good scale inhibition effect on calcium ions, iron ions, manganese ions, etc. in the wastewater.

Description

Technical Field

[0001] The present invention relates to the technical field of scale inhibitors, and particularly relates to a reducing scale inhibitor and a preparation method thereof. Background Art

[0002] In the production wastewater in the new energy field, there are certain concentrations of monochloramine, dichloramine, and iron and manganese oxides, and its ORP reaches more than 300 mv. When this wastewater is reused by the membrane method, it is necessary to reduce the ORP. However, when using conventional reverse osmosis reducing agents such as sodium bisulfite and sodium metabisulfite for treatment, the residual chlorine will first increase and then decrease after adding the medicine. If an excessive amount of sodium bisulfite and sodium metabisulfite is added, it is easy to cause the secondary pollution problem of the growth of sulfate-reducing bacteria, resulting in fast membrane fouling, difficult cleaning, and too high treatment cost. Summary of the Invention

[0003] The present invention provides a reducing scale inhibitor and a preparation method. In terms of mass percentage, its components include: 20-25% of a reducing agent component, 25-30% of a scale inhibitor component, 0.5-1% of a stabilizer component, 0.01-0.1% of a PH regulator, and the balance is water.

[0004] Further, the reducing agent is thiourea dioxide, sodium bisulfite or a composition of sodium metabisulfite and urea, wherein the mass percentage of thiourea dioxide is 1-1.5%, the mass percentage of sodium bisulfite or sodium metabisulfite (sulfur dioxide content greater than or equal to 60%) is 10-15%, and the mass percentage of urea is 3-5%. The three reducing agents are used in combination, which can effectively reduce and remove residual chlorine.

[0005] Further, the scale inhibitor component is a composition of polyphosphate, polycarboxylic acid and oxalic acid, wherein the mass percentage of polyphosphate is 10-20%, the mass percentage of polycarboxylic acid is 8-10%, and the mass percentage of oxalic acid is 5-10%.

[0006] Further, the polyphosphate is sodium hexametaphosphate. Sodium hexametaphosphate is an effective reverse osmosis scale inhibitor, which can form soluble chelates with scale-forming ions in the wastewater, such as calcium ions, iron ions, manganese ions, calcium ions, etc., thereby slowing down the formation of scale crystals and reducing the possibility of scale formation.

[0007] Further, the polycarboxylic acid is hydrolyzed maleic anhydride. The active carboxyl groups of hydrolyzed maleic anhydride can form chelates with calcium ions and magnesium ions, occupy the crystal lattice growth points, or be embedded inside the crystals, causing the lattice to be distorted and deformed, inhibiting crystal nucleation, and thus reducing the formation of scale.

[0008] Further, the oxalic acid can chelate with heavy metal ions in the wastewater, thereby forming stable water-soluble complexes and flocculating and precipitating.

[0009] Furthermore, the sodium hexametaphosphate is compounded with hydrolyzed maleic anhydride and oxalic acid, and has a strong dispersing effect, and can form a complex with scale-forming ions in wastewater, embed into scale crystals, and inhibit crystal precipitation and scaling.

[0010] Furthermore, the stabilizer component includes EDTA2Na and sodium silicate.

[0011] Furthermore, the pH regulator is aqueous ammonia.

[0012] Furthermore, the reducing scale inhibitor also includes water.

[0013] The present invention also provides a method for preparing a reducing scale inhibitor, which comprises the following steps:

[0014] Step (1): preparing reaction materials according to the weight percentage of raw materials, adding a certain amount of water into the reactor, heating to increase the temperature of the reaction materials, adding anti-scaling components, and stirring;

[0015] Step (2): slowly adding a pH regulator into the reaction kettle;

[0016] Step (3): slowly add the stabilizer component into the reaction kettle and stir for a period of time;

[0017] Step (4): lowering the temperature of the material in the reactor to a certain temperature, slowly adding the reducing agent component, and reacting for a certain time;

[0018] Step (5): Add a certain amount of water and stir and mix for a period of time;

[0019] Step (6): Filter to obtain a reddish brown reduced antiscalant.

[0020] Furthermore, in step (1), a certain amount of water is added in an amount of 30% by weight, and the temperature of the reaction material is

[0021] The temperature is raised to 60±5°C, the stirring time is 0.5-1 hour, the scale inhibitor components added include sodium hexametaphosphate, hydrolyzed maleic anhydride and oxalic acid; until the materials in the reactor are completely dissolved; the pH regulator added in step (2) is ammonia water, and the pH value of the reaction system is adjusted to 3.5-4.5; the stabilizer components added in step (3) include EDTA2Na and sodium silicate, and the stirring period is 30-60 minutes; in step (4), the temperature of the reaction material is reduced to 25-35°C, the reducing agent components added include thiourea dioxide, sodium bisulfite or sodium pyrosulfite, urea, and the reaction time is 1-2 hours; in step (5), a certain amount of water is added in a weight percentage of 15-30%, and the stirring mixing period is 30 minutes.

[0022] Compared with other reducing scale inhibitors, a reducing scale inhibitor of the present invention can significantly reduce the ORP and residual chlorine in wastewater with only a small dosage, and can effectively solve the secondary pollution problem caused by excessive use of reducing agents, which leads to the growth of sulfate-reducing bacteria. At the same time, the present invention can also play a role in scale inhibition, has good scale inhibition effects on iron and manganese, and has a relatively low production cost. Conventional scale inhibitors are usually strongly acidic and cannot coexist with reducing agents such as sodium bisulfite or sodium metabisulfite. The present invention selects sodium hexametaphosphate, oxalic acid, and hydrolyzed maleic anhydride as scale inhibitors, and then uses ammonia water to adjust the pH value of the system to 3.5 - 4.5. The prepared reducing scale inhibitor solves the problem that the scale inhibition component and the reducing component cannot be compatible, and can simultaneously play the roles of reducing ORP, residual chlorine, and scale inhibition, saving a dosing device and reducing the preparation time of the medicament. A reducing scale inhibitor of the present invention is particularly suitable for reverse osmosis membrane systems. Specific embodiments

[0023] The present invention will be further described below in conjunction with specific embodiments of the present invention.

[0024] Example 1

[0025] A reducing scale inhibitor, in terms of mass percentage, comprises the following components: thiourea dioxide 1%, sodium bisulfite 14.5%, urea 4.5%, EDTA2Na 0.4%, sodium silicate 0.1%, sodium hexametaphosphate 12%, hydrolyzed maleic anhydride 8%, oxalic acid 5%, ammonia water 0.01%, and water 45%.

[0026] The preparation method of the aforementioned reducing scale inhibitor comprises the following steps:

[0027] Step (1): Add 30% of water to the reaction kettle, heat to raise the temperature of the reaction materials to 60 ± 5 °C, add 10% of sodium hexametaphosphate, 9% of hydrolyzed maleic anhydride, and 6% of oxalic acid, and stir for 1 hour.

[0028] Step (2): Slowly add ammonia water to the reaction kettle until the pH value of the reaction solution is adjusted to 3.5;

[0029] Step (3): Slowly add 0.4% of EDTA2Na and 0.1% of sodium silicate to the reaction kettle, and stir for 30 min;

[0030] Step (4): Lower the temperature of the reaction materials in the reaction kettle to 25 °C, slowly add 1% of thiourea dioxide, 14.5% of sodium bisulfite, and 4.5% of urea, and react for 1 h;

[0031] Step (5): Add 15% of water, and stir and mix for 30 min.

[0032] Step (6): Filter to obtain a red-brown reducing scale inhibitor.

[0033] Example 2

[0034] A reducing scale inhibitor, in terms of mass percentage, comprises the following components: thiourea dioxide 1.3%, sodium bisulfite 14.7%, urea 4.7%, EDTA2Na 0.6%, sodium silicate 0.4%, sodium hexametaphosphate 10%, hydrolyzed maleic anhydride 10%, oxalic acid 10%, ammonia water 0.05%, and water 50%.

[0035] The reducing scale inhibitor product is prepared according to the preparation method steps of Example 1.

[0036] Example 3

[0037] A reducing scale inhibitor, in terms of mass percentage, comprises the following components: thiourea dioxide 1.5%, sodium bisulfite 15%, urea 5%, EDTA2Na 0.2%, sodium silicate 0.6%, sodium hexametaphosphate 15%, hydrolyzed maleic anhydride 9%, oxalic acid 6%, ammonia water 0.1%, and water 60%.

[0038] The reducing scale inhibitor product is prepared according to the preparation method steps of Example 1.

[0039] To verify the effect of the present invention, at the same dosage, a comparative test on the reduction and scale inhibition effects of the reducing scale inhibitor prepared in Example 3 is carried out with a single reducing agent and a scale inhibitor respectively.

[0040] The test water contains 0.2 mg / l of chloramine, 0.5 mg / l of iron, 2 mg / l of manganese, and 0.2 mg / l of sodium hypochlorite. The test temperature is 25°C, and the test results are shown in the following table:

[0041] Table 1: Reduction effect of the reducing scale inhibitor

[0042]

[0043] Table 1: Scale inhibition effect of the iron and manganese oxides of the reducing scale inhibitor

[0044]

Claims

1. A reducing scale inhibitor, characterized in that, In terms of mass percentage, its components include: 20 - 25% of reducing agent component, 25 - 30% of scale inhibitor component, 0.5 - 1% of stabilizer component, 0.01 - 0.1% of pH regulator, and the balance is water; the reducing agent component includes 1 - 1.5% of thiourea dioxide, 10 - 15% of sodium bisulfite or sodium metabisulfite, and 3 - 5% of urea. The three reducing agents are used in combination to effectively reduce and remove residual chlorine.

2. The reductive scale inhibitor according to claim 1, characterized in that, The polyphosphate is sodium hexametaphosphate.

3. The reductive scale inhibitor according to claim 1, characterized in that, The polycarboxylic acid is hydrolyzed maleic anhydride.

4. A reducing scale inhibitor according to claim 1, characterized in that, The stabilizer component includes EDTA2Na and sodium silicate.

5. A reducing scale inhibitor according to claim 1, wherein The pH regulator is ammonia water.

6. The preparation method of a reducing scale inhibitor according to any one of claims 1 to 5, characterized in that, It includes the following steps: Step (1): Prepare reaction materials according to the weight percentage of raw materials. Add a certain amount of water to the reaction kettle, heat to increase the temperature of the reaction materials, add the scale inhibitor component, and stir. Step (2): Slowly add the pH regulator to the reaction kettle until the pH value of the reaction solution is adjusted to 3.5 - 4.

5. Step (3): Slowly add the stabilizer component to the reaction kettle and stir for a period of time. Step (4): Lower the temperature of the reaction materials in the reaction kettle to a certain temperature, slowly add the reducing agent component, and react for a certain time. Step (5): Add a certain amount of water and stir and mix for a period of time. Step (6): Filter to obtain a red - brown reduced scale inhibitor.

7. The preparation method of the reducing scale inhibitor according to claim 6, characterized in that, In step (1), the weight percentage of the added certain amount of water is 30%. The temperature of the reaction materials is increased to 60 ± 5 °C, and the stirring time is 0.5 - 1 hour until all the materials in the reaction kettle are dissolved.

8. The preparation method of the reducing scale inhibitor according to claim 6, characterized in that, In step (3), the stirring time for a period of time is 30 - 60 min.

9. The preparation method of the reducing scale inhibitor according to claim 6, characterized in that, In step (4), the temperature of the reaction materials is lowered to 25 - 35 °C, and the reaction time is 1 - 2 h.

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