A scale inhibitor for cotton slurry black liquor and a preparation method thereof

Abstract

The application provides a scale inhibitor for cotton pulp black liquor and a preparation method thereof. The scale inhibitor is mainly prepared from the following raw materials in parts by mass: itaconic acid 15-25 parts, ferrous ammonium sulfate 5-15 parts, ammonium persulfate 5-10 parts, isopropyl alcohol 3-5 parts, polyaspartic acid 20-35 parts, polymaleic anhydride 15-25 parts, ethylenediamine tetramethyl phosphonic acid 10-15 parts and deionized water 30-50 parts. The scale inhibitor has high scale inhibition rate, stable chemical property and is not easy to hydrolyze. When the scale inhibitor is used in combination with zinc salt and copolymer, the scale inhibitor has good synergistic effect and solvency effect, can effectively delay the pipe and equipment blockage, prolong the cleaning cycle, ensure the long-term stable operation of the equipment and create effective protection.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wastewater treatment, in particular to a scale inhibitor for cotton pulp black liquor and a preparation method thereof. BACKGROUND

[0002] Cotton linters are used as raw materials to produce pulp, and the pulping process is basically the same as that of papermaking. A large amount of black liquor is generated in the process of alkali cooking and extraction. The composition of black liquor is complex and can be divided into organic matter and inorganic matter. The black liquor contains a large amount of suspended solids, organic pollutants and toxic substances, which will cause serious pollution if directly discharged into water bodies. Therefore, the treatment of papermaking black liquor is an inevitable requirement of modern environmental protection. The alkali recovery treatment method is a relatively effective method to solve the problem of black liquor. Through the four main sections of black liquor extraction, evaporation, combustion and causticization, SS, COD and BOD in the black liquor can be completely removed, and alkali can be recovered, and secondary steam can be generated. Due to the characteristics of high calcium content and high alkalinity of black liquor, scaling will occur in the pipeline and evaporator during the evaporation process of black liquor, which will affect the treatment effect. The cleaning process will affect normal production, and even cause equipment shutdown, safety accidents, etc.

[0003] At present, the composition of the black liquor scale inhibitor is single, the dosage is large, and the treatment effect is poor. It is necessary to develop a cotton pulp black liquor scale inhibitor, which has great economic and social benefits.

[0004] Therefore, the present application is proposed. SUMMARY

[0005] The first object of the present application is to provide a scale inhibitor for cotton pulp black liquor, which has high scale inhibition rate, stable chemical properties, is not easy to hydrolyze, can effectively delay the blockage of pipelines and equipment, prolong the cleaning cycle, and ensure the long-term stable operation of the equipment.

[0006] The second object of the present application is to provide a preparation method of the scale inhibitor for cotton pulp black liquor, which is simple to operate and has mild operating conditions.

[0007] In order to achieve the above objects of the present application, the following technical solutions are adopted:

[0008] The present application provides a scale inhibitor for cotton pulp black liquor, which is prepared from the following raw materials in mass fraction: 15-25 parts of itaconic acid, 5-15 parts of ferrous ammonium sulfate, 5-10 parts of ammonium persulfate, 3-5 parts of isopropyl alcohol, 20-35 parts of polyaspartic acid, 15-25 parts of polymaleic anhydride, 10-15 parts of ethylenediaminetetramethyl phosphonic acid, and 30-50 parts of deionized water.

[0009] Preferably, as a further specific embodiment, it is mainly prepared from: itaconic acid 20-24 parts, ferrous ammonium sulfate 10-13 parts, ammonium persulfate 7-9 parts, isopropyl alcohol 4-5 parts, polyaspartic acid 25-30 parts, polymaleic anhydride 20-24 parts, ethylenediamine tetramethyl phosphoric acid 12-14 parts and deionized water 35-45 parts.

[0010] Preferably, as a further specific embodiment, it is mainly prepared from: itaconic acid 23 parts, ferrous ammonium sulfate 12 parts, ammonium persulfate 8 parts, isopropyl alcohol 4 parts, polyaspartic acid 27 parts, polymaleic anhydride 23 parts, ethylenediamine tetramethyl phosphoric acid 13 parts and deionized water 44 parts.

[0011] Among the above-mentioned raw materials, the itaconic acid added in the present application contains two active carboxyl groups and a double bond in the molecule, and the double bond and the carboxyl group exhibit a conjugated relationship, so that the properties of itaconic acid are very active. In addition to being able to polymerize with itself, it can also be added to other monomers for polymerization, so that it forms a stable and not easily decomposed polymer. Therefore, the itaconic acid added in the present application can polymerize with various monomers in the black liquor, thereby forming a polymer, so that the substance obtained by polymerizing with the substances in the black liquor has stability and is not easily decomposed. The present application also adds ferrous ammonium sulfate and ammonium persulfate as a polymerization aid during the polymerization of the organic polymer, so that the substances present in the black liquor and the raw materials such as itaconic acid are better polymerized, thereby forming a stable polymer.

[0012] The polymaleic anhydride added in the present application is an organic fatty acid polymer, which has good stability, is easily soluble in water, and can produce very good scale inhibition effect on carbonates and phosphates. The carboxyl groups in the polymaleic anhydride molecule can form compounds with calcium, magnesium and other ions in water, and can cause lattice distortion, so that the precipitate is converted into loose water slag with good flowability. Therefore, after the scale inhibitor forms a compound with the ions in water, it will not block the equipment. Therefore, by adding polymaleic anhydride, the substances in the black liquor can be fully removed and the equipment is not easily blocked.

[0013] The main role of polyaspartic acid is scale inhibition and dispersion, and it also has good corrosion inhibition effect, which can inhibit the formation of calcium carbonate scale and other scale in the black liquor. In addition, polyaspartic acid has good dispersion effect, which can effectively prevent the corrosion of metal equipment. The present application adds polyaspartic acid and ethylenediamine tetramethyl phosphoric acid to form a high-efficiency and multifunctional corrosion and scale inhibitor through synergistic effect.

[0014] The present application also provides a preparation method of the above-mentioned scale inhibitor for cotton pulp black liquor, which comprises the following steps:

[0015] Add itaconic acid, ferrous ammonium sulfate, isopropyl alcohol and deionized water in sequence and heat;

[0016] Then ammonium persulfate was added into the mixture in several times, the temperature was kept at 80℃, and the stirring was reduced to 29℃ after 2h reaction;

[0017] Finally, polyaspartic acid, polymaleic anhydride and ethylenediamine tetramethylene phosphonic acid were added into the mixture and stirred uniformly.

[0018] Preferably, the temperature was heated to 80±2℃ after the addition of itaconic acid, ferrous ammonium sulfate, isopropyl alcohol and deionized water.

[0019] Preferably, ammonium persulfate was added into the mixture of itaconic acid, ferrous ammonium sulfate, isopropyl alcohol and deionized water in four times, and the interval time of each addition was 45min.

[0020] Preferably, the stirring time was 30min after the addition of polyaspartic acid, polymaleic anhydride and ethylenediamine tetramethylene phosphonic acid.

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] (1) The scale inhibitor provided by the present application has good scale inhibition effect, high scale inhibition rate, stable chemical property and high temperature resistance.

[0023] (2) The scale inhibitor has good synergistic effect and solvus effect when used in combination with zinc salt and copolymer. The scale inhibitor is non-toxic and friendly to the environment. DETAILED DESCRIPTION

[0024] The technical solutions of the present application will be described clearly and completely in combination with specific embodiments, but those skilled in the art will understand that the following described embodiments are part of the embodiments of the present application, not all the embodiments, and should not be regarded as limiting the scope of the present application. 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.

[0025] In order to more clearly describe the technical solutions in the present application, the following will be described in the form of specific embodiments.

[0026] Embodiment 1

[0027] Take 15 parts of itaconic acid, 5 parts of ferrous ammonium sulfate, 5 parts of ammonium persulfate, 3 parts of isopropyl alcohol, 20 parts of polyaspartic acid, 15 parts of polymaleic anhydride, 10 parts of ethylenediamine tetramethyl phosphonic acid and 30 parts of deionized water.

[0028] Then 15 parts of itaconic acid, 5 parts of ferrous ammonium sulfate, 3 parts of isopropyl alcohol and 30 parts of deionized water were added into the reaction kettle, the stirring rod was opened and the temperature was raised to 80℃, and the temperature was kept.

[0029] Then ammonium persulfate was added in four portions, with an interval of 45 minutes between each addition. After the addition was complete, the temperature was maintained at 80°C, and the reaction was allowed to proceed for 2 hours. The mixture was then stirred and cooled to 29°C.

[0030] Example 2

[0031] The specific preparation steps of the scale inhibitor are the same as in Example 1, except that the components are adjusted by mass parts as follows: 25 parts itaconic acid, 15 parts ferrous ammonium sulfate, 10 parts ammonium persulfate, 5 parts isopropanol, 35 parts polyaspartic acid, 25 parts polymaleic anhydride, 15 parts ethylenediaminetetramethylphosphate, and 50 parts deionized water.

[0032] Example 3

[0033] The specific preparation steps of the scale inhibitor are the same as in Example 1, except that the components are adjusted by mass to 20 parts itaconic acid, 10 parts ferrous ammonium sulfate, 7 parts ammonium persulfate, 4 parts isopropanol, 25 parts polyaspartic acid, 20 parts polymaleic anhydride, 12 parts ethylenediaminetetramethylphosphate, and 35 parts deionized water.

[0034] Example 4

[0035] The specific preparation steps of the scale inhibitor are the same as in Example 1, except that the components are adjusted by mass parts as follows: 24 parts itaconic acid, 13 parts ferrous ammonium sulfate, 9 parts ammonium persulfate, 5 parts isopropanol, 30 parts polyaspartic acid, 24 parts polymaleic anhydride, 14 parts ethylenediaminetetramethylphosphate, and 45 parts deionized water.

[0036] Example 5

[0037] The specific preparation steps of the scale inhibitor are the same as in Example 1, except that the components are adjusted by mass parts as follows: 23 parts itaconic acid, 12 parts ferrous ammonium sulfate, 8 parts ammonium persulfate, 4 parts isopropanol, 27 parts polyaspartic acid, 23 parts polymaleic anhydride, 13 parts ethylenediaminetetramethylphosphate, and 44 parts deionized water.

[0038] Example 6

[0039] The specific preparation steps of the scale inhibitor are the same as in Example 5, except that after adding itaconic acid, ferrous ammonium sulfate, isopropanol and deionized water to the reaction vessel, the temperature is raised to 78°C and maintained.

[0040] Example 7

[0041] The specific preparation steps of the scale inhibitor are the same as in Example 5, except that the mass fraction of itaconic acid is adjusted to 16 parts.

[0042] Example 8

[0043] The specific preparation steps of the scale inhibitor are the same as in Example 5, except that the mass fraction of polyaspartic acid is adjusted to 22 parts.

[0044] Example 9

[0045] The specific preparation steps of the scale inhibitor were consistent with Example 5, except that the mass fraction of polymaleic anhydride was adjusted to 17 parts.

[0046] Example 10

[0047] The specific preparation steps of the scale inhibitor were consistent with Example 5, except that the mass fraction of ethylenediamine tetramethylene phosphonic acid was adjusted to 10 parts.

[0048] Comparative Example 1

[0049] The specific preparation steps of the scale inhibitor were consistent with Example 5, except that itaconic acid was not added.

[0050] Comparative Example 2

[0051] The specific preparation steps of the scale inhibitor were consistent with Example 5, except that the mass fraction of itaconic acid was adjusted to 10 parts.

[0052] Comparative Example 3

[0053] The specific preparation steps of the scale inhibitor were consistent with Example 5, except that polyaspartic acid was not added.

[0054] Comparative Example 4

[0055] The specific preparation steps of the scale inhibitor were consistent with Example 5, except that the mass fraction of polyaspartic acid was adjusted to 15 parts.

[0056] Comparative Example 5

[0057] The specific preparation steps of the scale inhibitor were consistent with Example 5, except that polymaleic anhydride was not added.

[0058] Comparative Example 6

[0059] The specific preparation steps of the scale inhibitor were consistent with Example 5, except that the mass fraction of polymaleic anhydride was adjusted to 10 parts.

[0060] Comparative Example 7

[0061] The specific preparation steps of the scale inhibitor were consistent with Example 5, except that ethylenediamine tetramethylene phosphonic acid was not added.

[0062] Comparative Example 8

[0063] The specific preparation steps of the scale inhibitor were consistent with Example 5, except that the mass fraction of ethylenediamine tetramethylene phosphonic acid was adjusted to 5 parts.

[0064] Comparative Example 9

[0065] The specific preparation steps of the scale inhibitor were consistent with Example 5, except that ammonium persulfate was not added.

[0066] Comparative Example 10

[0067] The specific preparation steps of the scale inhibitor are consistent with those in Example 5, except that the mass fraction of ammonium persulfate is adjusted to 2 parts.

[0068] Comparative Example 11

[0069] The specific preparation steps of the scale inhibitor are consistent with those in Example 5, except that after itaconic acid, ferrous ammonium sulfate, isopropyl alcohol and deionized water are added to the reaction kettle, the temperature is raised to 70°C and the temperature is maintained.

[0070] The scale inhibitors prepared in Examples 1-10 and Comparative Examples 1-11 and commercially available scale inhibitors are subjected to performance testing, and the final scale inhibition rate results are shown in Table 1.

[0071] Table 1 Test results of scale inhibitors of examples and comparative examples

[0072]

[0073]

[0074] According to the above data, the following conclusions can be drawn:

[0075] From the data in the table, it can be seen that the scale inhibition rates of the scale inhibitors prepared by the scheme of the present application in Examples 1-10 are all 93%, which shows excellent performance and good scale inhibition effect. By comparing Examples 1-5, it can be found that when the components and the ratio of the scale inhibitors obtained by the method of the present application are different, the scale inhibition effect of the scale inhibitor will be affected. When the components of the scale inhibitor are not within the range provided by the present application, the scale inhibition rate of the scale inhibitor prepared is low, the scale inhibition effect is poor, and the compounds formed by the scale inhibitor and the substances in the black liquor are unstable and easy to decompose. Only when the components are itaconic acid 23 parts, ferrous ammonium sulfate 12 parts, ammonium persulfate 8 parts, isopropyl alcohol 4 parts, polyaspartic acid 27 parts, polymaleic anhydride 23 parts, ethylenediaminetetramethyphosphonic acid 13 parts and deionized water 44 parts by mass fraction, the scale inhibition effect of the scale inhibitor prepared is the best, the chemical property is stable and not easy to hydrolyze, and it is resistant to high temperature.

[0076] Comparing example 5 and example 7 in table 1 with comparative examples 1-2, it can be found that the added itaconic acid is extremely important, because the added itaconic acid contains two active carboxyl groups and a double bond in the molecule, and the double bond and the carboxyl group present a conjugated relationship, so that the property of itaconic acid is very active, in addition to being able to polymerize with itself, it can also be added to other monomers to polymerize, so that it forms a stable and not easily decomposed polymer, therefore, the added itaconic acid can polymerize with various monomers in the black liquor to form a polymer, so that the substance obtained by polymerizing with the substances in the black liquor has stability and is not easily decomposed. Only when the mass fraction of the added itaconic acid is 23 parts, the scale inhibition effect of the prepared scale inhibitor is optimal.

[0077] Comparing example 8, example 9 and comparative examples 3-6 in table 1, it can be found that the added polymaleic anhydride and polyaspartic acid have a certain influence on the scale inhibition effect of the finally prepared scale inhibitor, because polymaleic anhydride is an organic fatty acid polymer, has good stability, is easily soluble in water, and can produce very good scale inhibition effect on carbonates and phosphates, the carboxyl group in the polymaleic anhydride molecule can form a compound with calcium, magnesium and other ions in water, and can cause lattice distortion, so that the precipitate is converted into loose water slag with good flowability, so that the compound formed by the scale inhibitor and the ions in water will not block the equipment, thus, by adding polymaleic anhydride, the substances in the black liquor can be fully removed. The main role of polyaspartic acid is scale inhibition and dispersion, and it has good corrosion inhibition effect, can inhibit the formation of calcium carbonate scale and other scale in the black liquor, and polyaspartic acid has good dispersion effect, can effectively prevent the corrosion of metal equipment. And by adding polyaspartic acid and ethylenediamine tetramethyl phosphonic acid to synergize, a high-efficiency and multifunctional corrosion and scale inhibitor is formed.

[0078] Comparing comparative examples 9-10 and example 5, it can be found that the added ferrous ammonium sulfate and ammonium persulfate are used as polymerization aids in the polymerization of the organic high polymer, so that the substances in the black liquor and the raw materials such as itaconic acid can be better polymerized, so that stable high molecular polymers can be fully formed. If ferrous ammonium sulfate and ammonium persulfate are not added, the compound formed by the scale inhibitor and the substances in the black liquor is unstable and is easily decomposed at high temperature, so that the substances in the black liquor cannot be removed.

[0079] In summary, the scale inhibitor of the present application has high scale inhibition rate, stable chemical properties and is not easily hydrolyzed. When used with zinc salt, copolymer and the like, it has good synergistic effect and solvus effect, can effectively delay the fouling of pipelines and equipment, prolong the cleaning cycle, ensure the long-term stable operation of the equipment and create effective protection.

[0080] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A scale inhibitor for cotton slurry black liquor, characterized by, It is prepared by the following raw materials in mass fraction: itaconic acid 15-25 parts, ferrous ammonium sulfate 5-15 parts, ammonium persulfate 5-10 parts, isopropyl alcohol 3-5 parts, polyaspartic acid 20-35 parts, polymaleic anhydride 15-25 parts, ethylenediamine tetramethyl phosphonic acid 10-15 parts and deionized water 30-50 parts; its preparation method comprises the following steps: Itaconic acid, ferrous ammonium sulfate, isopropyl alcohol and deionized water are added in sequence, and heated to 80±2℃; Ammonium persulfate is added in 4 times, and the interval of each time is 45min, the temperature is kept at 78-82℃, and after 2h reaction, the temperature is reduced to 29℃ by stirring; Finally, polyaspartic acid, polymaleic anhydride and ethylenediamine tetramethyl phosphonic acid are added, and stirred for 30min.

2. The scale inhibitor of claim 1, wherein, It is prepared by the following raw materials in mass fraction: itaconic acid 20-24 parts, ferrous ammonium sulfate 10-13 parts, ammonium persulfate 7-9 parts, isopropyl alcohol 4-5 parts, polyaspartic acid 25-30 parts, polymaleic anhydride 20-24 parts, ethylenediamine tetramethyl phosphonic acid 12-14 parts and deionized water 35-45 parts.

3. The scale inhibitor of claim 1, wherein, It is prepared by the following raw materials in mass fraction: itaconic acid 23 parts, ferrous ammonium sulfate 12 parts, ammonium persulfate 8 parts, isopropyl alcohol 4 parts, polyaspartic acid 27 parts, polymaleic anhydride 23 parts, ethylenediamine tetramethyl phosphonic acid 13 parts and deionized water 44 parts.

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