Disclosure of Invention
In order to overcome the defect of poor thermal stability of the existing polyaspartic acid scale inhibitor, the invention aims to provide a high-temperature-resistant modified polyaspartic acid scale inhibitor and a preparation method and a use method thereof.
In order to achieve the purpose, the invention adopts the following technical scheme to realize the purpose:
the invention discloses a preparation method of a high-temperature-resistant modified polyaspartic acid scale inhibitor, which comprises the following steps:
maleic anhydride and urea are used as raw materials and react in a mixed acid solution to obtain polysuccinimide;
the polysuccinimide and prolinamide are subjected to ring-opening grafting reaction to prepare the high-temperature-resistant modified polyaspartic acid scale inhibitor.
Preferably, the preparation method of the high-temperature-resistant modified polyaspartic acid scale inhibitor is characterized by comprising the following steps of:
1) preparation of ammonium hydrogen maleate
Fully dissolving maleic anhydride in water to prepare a maleic anhydride aqueous solution, adding urea powder into the maleic anhydride aqueous solution, and generating ammonium hydrogen maleate through a ring-opening reaction;
2) preparation of polysuccinimide
Under the reflux condition, heating the reaction solution containing ammonium hydrogen maleate in the step 1) to 160 +/-5 ℃, then adding the mixed acid solution, heating to 180 +/-5 ℃, and reacting for 1.5-3 h to obtain polysuccinimide;
3) preparation of modified polyaspartic acid
Under the condition of water bath at 40-60 ℃, polysuccinimide and prolinamide are subjected to ring opening grafting reaction in water, alkali liquor is added to open the ring of the part which is not grafted in a polysuccinimide chain segment, after the reaction is carried out for 12-24 ℃, the pH value of a reaction system is adjusted to be neutral, and a product is precipitated by alcohol and dried to prepare modified polyaspartic acid, namely the high-temperature-resistant modified polyaspartic acid scale inhibitor.
Further, in step 1), an aqueous ammonium hydrogen maleate solution is prepared: adding maleic anhydride and deionized water into a three-neck flask with a condensing device, and magnetically stirring in an oil bath kettle to fully dissolve. Uniformly adding urea powder into maleic anhydride aqueous solution to react, and in the process, maleic anhydride and ammonia donor urea are subjected to ring-opening reaction to generate ammonium hydrogen maleate.
Preferably, in the step 1), the temperature for dissolving the maleic anhydride is 60-80 ℃, and the molar ratio of the maleic anhydride to the urea is 1: 0.5-1: 0.7, and the temperature of the ring-opening reaction is 80-110 ℃.
Further, in step 2), Polysuccinimide (PSI) synthesis: introducing cold water of 5 ℃ into a condensation pipe for condensation and reflux, raising the temperature of the generated ammonium hydrogen maleate solution to 160 +/-5 ℃, and adding mixed acid of sulfuric acid and phosphoric acid into the system. Then heating to 180 +/-5 ℃ for continuous reaction, and polymerizing the ammonium hydrogen maleate monomer to generate orange-red polysuccinimide.
Further, in step 3), modification of polyaspartic acid: performing ring opening grafting on polysuccinimide and goose yellow prolinamide in deionized water in a water bath at 40-60 ℃, then adding sodium hydroxide alkali liquor to perform ring opening on the part which is not grafted in the polysuccinimide chain segment, adjusting the pH value to be neutral after reacting for a period of time, separating out by using absolute ethyl alcohol, separating and drying to obtain light yellow brittle solid cyclic micromolecule modified polyaspartic acid (PASP-Pro).
In addition, similarly, polyaspartic acid synthesis can employ: hydrolyzing and ring-opening polysuccinimide in sodium hydroxide alkali liquor in a water bath environment at 40-60 ℃ to obtain polyaspartic acid, and then separating out the polyaspartic acid by using absolute ethyl alcohol. Separating and drying to obtain light yellow viscous Polyaspartic Acid (PASP).
Preferably, in the step 2), the mixed acid solution is added to the reaction kettle and is prepared from sulfuric acid and phosphoric acid according to the volume ratio of 1: 1. More preferably, the dosage of the mixed acid of the sulfuric acid and the phosphoric acid is 1.6-2 mL.
Preferably, in step 3), the molar ratio of polysuccinimide to prolinamide is 1: 0.5-1: 0.75; the open-loop grafting reaction time is 4-8 h.
Preferably, in the step 3), the alkali liquor used for hydrolysis and conference opening adopts a sodium hydroxide solution with the concentration of 2.5-3 mol/L, wherein the volume of the sodium hydroxide solution added per g of polysuccinimide is 5-6 mL.
Preferably, before step 3), an operation of purifying the polysuccinimide prepared in step 2) is further included, specifically including:
taking out the prepared crude polysuccinimide product, drying, completely dissolving the crude polysuccinimide product by adopting N-N-dimethylformamide, filtering, collecting filtrate by adopting absolute ethyl alcohol, filtering, separating by suction after a product is separated out, and drying;
after repeating the purification operation 2 times, the product was ground to obtain purified polysuccinimide.
Specifically, the crude orange-red solid polysuccinimide attached to the wall of the flask was taken out, dried, completely dissolved with N-Dimethylformamide (DMF), poured into a funnel with qualitative analysis filter paper, filtered, and the filtrate was collected in a beaker containing absolute ethanol. Polysuccinimide is precipitated in pink floccule in absolute ethyl alcohol, and is subjected to suction filtration and separation, and the obtained product is placed in a vacuum oven for drying. And repeating the purification step for 2 times, and grinding to obtain the dark red purified polysuccinimide.
Further preferably, the volume ratio of the absolute ethyl alcohol to the N-N-dimethylformamide used for collecting the filtrate is more than 5.
The invention also discloses the high-temperature-resistant modified polyaspartic acid scale inhibitor prepared by the preparation method.
The invention also discloses a use method of the high-temperature-resistant modified polyaspartic acid scale inhibitor, and when the high-temperature-resistant modified polyaspartic acid scale inhibitor is used for water system treatment at the temperature of below 90 ℃, long-acting scale inhibition effect can be maintained;
when the high-temperature-resistant modified polyaspartic acid scale inhibitor is treated in a water system with local temperature reaching 170 ℃, the scale inhibition effect can be maintained for 3.5 h;
when in use, the water system with the pH value of 6.0-8.5 and the calcium ion concentration lower than 700mg/L is suitable;
the concentration of the high-temperature-resistant modified polyaspartic acid scale inhibitor in use is 10-20 mg/L.
Compared with the prior art, the invention has the following beneficial effects:
the preparation method of the high-temperature-resistant modified polyaspartic acid scale inhibitor disclosed by the invention has the advantages that the polysuccinimide precursor is synthesized by using a maleic anhydride method, the synthesis condition is mild, the novel environment-friendly high-temperature-resistant calcium carbonate scale inhibitor is synthesized by using the nitrogen-containing heterocyclic small-molecule prolinamide modified polyaspartic acid, the reaction condition is mild, the reaction raw materials are easy to obtain, and the preparation method is suitable for large-scale production.
The modified polyaspartic acid scale inhibitor prepared by the method is nitrogen-containing heterocyclic small molecule modified polyaspartic acid, belongs to a phosphorus-free environment-friendly scale inhibitor, and is characterized in that in the modification process of polyaspartic acid, a heterocyclic group with a stable structure is selected to perform amidation reaction with polyaspartic acid, and a rigid prolinamide molecule is grafted on linear polyaspartic acid, so that the steric hindrance of the original polyaspartic acid chain is increased, and the chain segment is not easy to move. On the other hand, a new hydrogen bond is generated, which is beneficial to maintaining the stable structure of the polymer. Under the action, the modified polyaspartic acid scale inhibitor has stable structure at high temperature and maintains high-efficiency scale inhibition effect. The scale inhibitor overcomes the defect of poor scale inhibition effect of the existing polyaspartic acid at high temperature, has excellent scale inhibition performance on a calcium carbonate type scale formation system, and is suitable for water circulation systems with local high temperature in urban geothermal heating systems, oil well exploitation production and the like.
The modified polyaspartic acid scale inhibitor disclosed by the invention plays a scale inhibition role at high temperature, is obviously different from a traditional organic phosphoric acid system, and realizes a green scale inhibition target process, so that the prepared modified polyaspartic acid scale inhibitor can be used in the water fields of industrial circulating water, boiler water, geothermal water, urban heating water, oil field exploitation and the like.
Detailed Description
In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
The invention is described in further detail below with reference to the accompanying drawings:
the invention discloses a preparation method of a high-temperature-resistant polyaspartic acid scale inhibitor synthesized by modifying nitrogen-containing heterocyclic micromolecules, which comprises the following steps:
(A) preparation of Polysuccinimide (PSI) by maleic anhydride method
And adding 20-30 g of maleic anhydride solid and 20-30 ml of deionized water into a 500ml three-neck flask with a condensing device, magnetically stirring, controlling the temperature of an oil bath to be 80 +/-5 ℃, and heating for 60-90 min to completely dissolve the maleic anhydride.
Controlling the molar ratio of the maleic anhydride to the urea to be 1: 0.5-1: 0.7, uniformly adding urea powder into the obtained homogeneous maleic anhydride solution, controlling the temperature of an oil bath to be 80 +/-5 ℃, and heating for 60-90 min to ensure that the maleic anhydride and the ammonia donor urea fully generate ammonium hydrogen maleate through a ring-opening reaction.
And (3) introducing cold water with the temperature of 5 ℃ into a condensation pipe of the three-neck flask to start condensation, continuously heating to 160 +/-5 ℃, keeping for a period of time, boiling the colorless ammonium hydrogen maleate solution and gradually becoming turbid, and finding that a small amount of orange solid is generated on the wall of the three-neck flask. Slowly adding (paying attention to the dropping speed to prevent the bumping) 1.6-2 ml of phosphoric acid and sulfuric acid into a three-neck flask, wherein the volume ratio of the phosphoric acid to the sulfuric acid is 1: the mixed acid solution of 1 is used as a dehydrating agent to promote the polymerization reaction, and then the mixed acid is added, the temperature is raised to 180 +/-5 ℃, and the reaction is maintained for 1.5-3 hours.
(B) Purified Polysuccinimide (PSI)
Taking out the orange-red polysuccinimide solid obtained in the step (A), drying, adding 20ml of N-N-Dimethylformamide (DMF), dissolving into an orange-red solution, filtering by using No. 102 qualitative filter paper, and collecting the filtrate by using absolute ethyl alcohol, wherein the volume of the used ethyl alcohol is at least more than 100 ml. Polysuccinimide is precipitated in the form of pink flocculent precipitate at the bottom of absolute ethyl alcohol, and the obtained pink filter cake is put in a vacuum drying oven for complete drying at 60-80 ℃ after being subjected to suction filtration and separation.
And repeating the steps for 2 times, and drying and grinding the obtained product to obtain the dark red precursor polysuccinimide.
(C) Preparation of Polyaspartic Acid (PASP) and modified polyaspartic acid (PASP-Pro)
(C1) In a water bath environment at 60 ℃, 2g of the polysuccinimide powder purified in the step (B) is placed in 10ml of 2.5mol/L sodium hydroxide alkali liquor for hydrolysis ring opening, the orange polysuccinimide solution gradually becomes light yellow, and after hydrolysis time is 12-24 hours, the polyaspartic acid solution with proper molecular weight is obtained. Adding appropriate amount of hydrochloric acid to adjust pH to neutral, dripping anhydrous ethanol with volume more than 50ml, and precipitating polyaspartic acid at the bottom of the anhydrous ethanol to obtain yellowish mucus. Separating and drying to obtain the light yellow viscous polyaspartic acid.
(C2) In a water bath at 60 ℃, 2g of the polysuccinimide powder purified in the step (B) is completely dissolved in 10ml of deionized water, 1.2-1.8 g of the goose yellow prolinamide powder is slowly added to the polysuccinimide powder for ring-opening grafting, after reaction for 4-8 h, 5ml of 2.5mol/L sodium hydroxide alkali liquor is added, the part of the polysuccinimide chain segment which is not grafted with the monomer is hydrolyzed and subjected to ring-opening in an alkaline environment, after reaction for 12-18 h, a proper amount of hydrochloric acid is added to adjust the pH value to be neutral, then anhydrous ethanol with the volume of more than 75ml is added dropwise, modified polyaspartic acid is separated out at the bottom of the anhydrous ethanol, and after separation and drying, light yellow brittle solid cyclic micromolecular modified polyaspartic acid is obtained.
Example 1 (prolinamide-modified polyaspartic acid)
Step 1: 20g of maleic anhydride and 20ml of distilled water were placed in a 250ml three-necked round-bottomed flask with a condenser and dissolved by magnetic stirring for 1 hour under an oil bath at 80 ℃. 9g of urea powder was slowly added to the solution and stirred magnetically for 1h until well mixed. After the experiment started, 5 ℃ condensed water was switched on, the oil bath temperature was raised to 160 ℃, and then the mixture was added in a volume ratio of 1:1, 2ml of mixed acid of sulfuric acid and phosphoric acid, continuously heating to 180 ℃, and continuously reacting for 3 hours to generate orange red Polysuccinimide Solid (PSI) on the inner wall surface of the beaker.
Step 2: and (2) taking the orange-red polysuccinimide solid obtained in the step (1) out, drying, adding 20ml of N-N-dimethylformamide to dissolve the orange-red polysuccinimide solid into an orange-red solution, filtering, and collecting filtrate by using enough absolute ethyl alcohol. Filtering and separating pink flocculent precipitate separated out from the absolute ethyl alcohol, and drying the obtained filter cake in a vacuum oven at the temperature of 80 ℃ for 24 hours.
The purification step was repeated 2 times and ground to give a dark red polysuccinimide powder.
And step 3: and (2) completely dissolving 2g of the purified polysuccinimide powder obtained in the step (2) in 10ml of deionized water in a water bath at 60 ℃, adding 1.5g of prolinamide powder, and carrying out ring-opening grafting reaction for 4-8 h. Adding 5ml of 2.5mol/L sodium hydroxide alkali liquor, carrying out hydrolysis reaction for 12-18 h, adjusting the pH to be neutral by using hydrochloric acid, dripping into 100ml of absolute ethyl alcohol, separating and drying precipitated precipitate, and purifying for 1-2 times to obtain the prolinamide modified polyaspartic acid.
The infrared spectrum of the prolinamide modified polyaspartic acid obtained is shown in FIG. 1. The infrared spectra of the modified molecules prolinamide (Pro), Polyaspartic Acid (PASP) and modified polyaspartic acid (PASP-Pro) are included in fig. 1.
Comparative example 1 (polyaspartic acid)
Step 1 and step 2 are the same as in the example.
And step 3: and (2) in a water bath at 60 ℃, hydrolyzing and ring-opening 2g of the purified polysuccinimide powder obtained in the step (2) in 10ml of 2.5mol/L sodium hydroxide alkali liquor for 24h, adjusting the pH to be neutral by using hydrochloric acid, dripping into 100ml of absolute ethyl alcohol, separating and drying the separated precipitate, and purifying for 1-2 times to obtain the polyaspartic acid. The prepared polyaspartic acid was prepared as a dilute solution with ultrapure water.
COMPARATIVE EXAMPLE 2 (blank group)
An equal volume of ultrapure water was used as a blank for the scale inhibitor solution.
And (3) testing the scale inhibition performance: and (3) carrying out scale inhibition performance test on polyaspartic acid and prolinamide modified polyaspartic acid according to a calcium carbonate deposition method for measuring scale inhibition performance of GB/T166322008 water treatment agents.
Preparing a test solution: adding 100ml of calcium chloride solution into a 250ml volumetric flask to ensure that the addition of calcium ions is 60 mg; adding a certain volume of scale inhibitor solution by a pipette, wherein the adding amount of the polyaspartic acid or the prolinamide modified polyaspartic acid is 5mg, and shaking up; then 100ml of sodium bicarbonate solution was slowly added to make the amount of bicarbonate ions added 183mg, and ultrapure water was supplemented to a volume of 250 ml.
Application experiment one: taking 15 250ml round-bottom flasks numbered 1-15, and accurately adding Ca into the flasks 1-15 according to the preparation steps of the test solution2+Concentration of 240mg/L, HCO3 -The concentration is 732mg/L, wherein the prolinamide modified polyaspartic acid prepared in the embodiment 1 of the invention is added into a No. 1-5 flask, and the concentration is 20 mg/L; adding polyaspartic acid prepared in comparative example 1 of the invention into a No. 6-10 flask, wherein the concentration is 20 mg/L; an equal volume of ultrapure water was added to flask 11-15 as a blank control. Adjusting the pH to 7Placing the components in 50, 60, 70, 80, 90 deg.C constant temperature water bath kettle respectively, water bath time is 10 hr, cooling the test solution to room temperature after experiment, collecting the filtrate, and testing Ca by ion chromatography2+And (4) calculating the scale inhibition rate. The results of the measurements are shown in Table 1 and are plotted in FIG. 2.
Table 1: the duration of the constant temperature water bath is controlled to be 10 hours, and the constant temperature affects the calcium carbonate scale resistance of the polyaspartic acid and the modified polyaspartic acid.
TABLE 1
Example 1
|
1(50℃)
|
2(60℃)
|
3(70℃)
|
4(80℃)
|
5(90℃)
|
Scale inhibition rate
|
96.0
|
94.1
|
95.6
|
95.3
|
88.2
|
Comparative example 1
|
6(50℃)
|
7(60℃)
|
8(70℃)
|
9(80℃)
|
10(90℃)
|
Scale inhibition rate
|
94.1
|
93.0
|
96.1
|
92.2
|
86.9 |
From the results of table 1 and fig. 2, it can be seen that: when the water bath temperature of the static experiment is lower, the scale inhibition effect difference of the polyaspartic acid and the modified polyaspartic acid is not large, and when the water bath temperature is higher, the scale inhibition effect of the modified polyaspartic acid is higher than that of the unmodified polyaspartic acid.
Application experiment two: taking 15 250ml round-bottom flasks numbered 1-15, and accurately adding Ca into the flasks 1-15 according to the preparation steps of the test solution2+Concentration of 240mg/L, HCO3 -The concentration is 732mg/L, wherein the prolinamide modified polyaspartic acid prepared in the embodiment 1 of the invention is added into a No. 1-5 flask, and the concentration is 20 mg/L; adding polyaspartic acid prepared in comparative example 1 of the invention into a No. 6-10 flask, wherein the concentration is 20 mg/L; an equal volume of ultrapure water was added to flask 11-15 as a blank control. Adjusting pH to 7, placing the above components in 80 deg.C constant temperature water bath for 6, 8, 10, 15, and 20 hr, cooling the test solution to room temperature, collecting the filtrate, and testing Ca by ion chromatography2+And (4) calculating the scale inhibition rate. The results of the measurements are shown in Table 2 and are plotted in FIG. 3.
Table 2: the temperature of the constant-temperature water bath is controlled to be 80 ℃, and the influence of different constant-temperature time lengths on the calcium carbonate scale resistance of the polyaspartic acid and the modified polyaspartic acid is avoided.
TABLE 2
Example 1
|
1(6h)
|
2(8h)
|
3(10h)
|
4(15h)
|
5(20h)
|
Scale inhibition rate
|
93.9
|
95.3
|
97.3
|
96.9
|
85.2
|
Comparative example 1
|
6(6h)
|
7(8h)
|
8(10h)
|
9(15h)
|
10(20h)
|
Scale inhibition rate
|
94.1
|
92.2
|
94.6
|
84.7
|
74.4 |
From the results of table 2 and fig. 3, it can be seen that: when the water bath temperature is controlled to be 80 ℃, the scale inhibition effect of the polyaspartic acid and the modified polyaspartic acid is reduced along with the prolonging of the water bath time, but the scale inhibition effect of the modified polyaspartic acid at the same time is obviously higher than that of the modified polyaspartic acid at the same time.
Application experiment three: and (3) marking 8 hydrothermal kettles by 1-8, adding the prolinamide modified polyaspartic acid solution prepared in the example 1 into No. 1-4 hydrothermal kettles, adding the polyaspartic acid prepared in the comparative example 1 into No. 5-8 hydrothermal kettles, respectively placing the hydrothermally modified polyaspartic acid solutions in high-temperature drying ovens at 110 ℃, 130 ℃, 150 ℃ and 170 ℃ for pretreatment for 3.5 hours, and then taking out and cooling to room temperature. Taking 9 250ml round-bottom flasks numbered 1-9, and accurately adding Ca into the flasks 1-9 according to the preparation steps of the test solution2+Concentration of 240mg/L, HCO3 -The concentration is 732mg/L, wherein pretreated prolinamide modified polyaspartic acid is added into a No. 1-4 flask, and the concentration is 20 mg/L; adding the polyaspartic acid prepared in comparative example 1 into a No. 5-8 flask, wherein the concentration is 20 mg/L; an equal volume of ultrapure water was added to flask 9 as a blank control. Adjusting pH to 7, placing the above components in 80 deg.C constant temperature water bath for 10 hr, cooling the test solution to room temperature, filtering, and measuring Ca content in the filtrate by ion chromatography2+And (4) calculating the scale inhibition rate. The results of the measurements are shown in Table 3 and plotted in FIG. 4. Table 3: after high-temperature pretreatment for 3.5h, carrying out constant-temperature water bath at 80 ℃ for 10h, wherein the pretreatment temperature has influence on the calcium carbonate scale resistance of the polyaspartic acid and the modified polyaspartic acid.
TABLE 3
Example 1
|
1(110℃)
|
2(130℃)
|
3(150℃)
|
4(170℃)
|
Scale inhibition rate
|
94.6
|
90.8
|
87.1
|
61.7
|
Comparative example 1
|
5(110℃)
|
6(130℃)
|
7(150℃)
|
8(170℃)
|
Scale inhibition rate
|
85.7
|
82.1
|
73.6
|
43.0 |
From the results of table 3 and fig. 4, it can be seen that: along with the increase of the pretreatment temperature, the scale inhibition effect of the polyaspartic acid and the modified polyaspartic acid is reduced in a static test, but the scale inhibition effect of the modified polyaspartic acid is obviously higher than that of the non-modified polyaspartic acid.
Application experiment four: taking 18 250ml round-bottom flasks numbered 1-18, and controlling Ca in the flasks 1-6, 7-12 and 13-18 according to the preparation steps of the test solution2+The concentrations of the proline modified polyaspartic acid are respectively 120, 240, 360, 480, 600 and 720mg/L, and the proline modified polyaspartic acid prepared in the embodiment 1 of the invention is added into a No. 1-6 flask, and the concentration is 20 mg/L; adding polyaspartic acid prepared in comparative example 1 of the invention into a No. 7-12 flask, wherein the concentration is 20 mg/L; an equal volume of ultrapure water was added to flask 13-18 as a blank control. Accurately adding HCO into No. 1-18 flask3 -The concentration is 732mg/L, the pH is adjusted to be 7, each group is placed in a water bath kettle with the constant temperature of 80 ℃, the water bath time is 10h, and the experiment is carried outCooling the sample solution to room temperature after the reaction is finished, and measuring Ca in the filtered filtrate by adopting ion chromatography2+And (4) calculating the scale inhibition rate. The results of the measurements are shown in Table 4 and are plotted in FIG. 5.
Table 4: controlling the duration of the constant-temperature water bath to be 10h and Ca in the solution2+Effect of concentration on calcium carbonate Scale inhibition Properties of the polyaspartic acid and modified polyaspartic acid of the present invention
TABLE 4
Example 1
|
1(120)
|
2(240)
|
3(360)
|
4(480)
|
5(600)
|
6(720)
|
Scale inhibition rate
|
95.2
|
95.3
|
93.2
|
79.3
|
77.1
|
70.2
|
Comparative example 1
|
7(120)
|
8(240)
|
9(360)
|
10(480)
|
11(600)
|
12(720)
|
Scale inhibition rate
|
96.4
|
92.2
|
94.7
|
81.9
|
80.7
|
74.6 |
From the results of table 4 and fig. 5, it can be seen that: along with the increase of the concentration of calcium ions in the solution, the scale inhibition effect of the polyaspartic acid and the modified polyaspartic acid is slowly reduced, and the scale inhibition effect of the modified polyaspartic acid is slightly lower than that of unmodified polyaspartic acid, but the overall effect is similar.
The above are only the specific examples and comparative examples of the present invention, and the results of the specific embodiments show that, after high-temperature pretreatment in a water bath with temperature change and constant temperature for a long time, the scale inhibition effect of the proline-modified polyaspartic acid prepared in the examples on calcium carbonate is obviously higher than that of the unmodified polyaspartic acid in the comparative examples, which shows that the proline-modified polyaspartic acid obviously improves the high-temperature scale inhibition performance of polyaspartic acid on calcium carbonate systems. In addition, under the conditions of high mineralization and high calcium water quality, the proline amide modified polyaspartic acid shows the scale inhibition performance similar to that of the polyaspartic acid, and the proline amide modified polyaspartic acid can stably play the role of calcium carbonate scale inhibition in a high mineralization and high calcium water system.
The above-mentioned contents are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modification made on the basis of the technical idea of the present invention falls within the protection scope of the claims of the present invention.