CN105233699B - Itaconic acid aspartic acid copolymerization research of non-phosphorus scale inhibitor and preparation method thereof - Google Patents

Abstract

The invention discloses an itaconic acid-aspartic acid copolymerized non-phosphorus scale inhibitor, which is formed by copolymerizing itaconic acid and aspartic acid as monomers, and the general formula of the polymer is as follows: In formula (I), m, m ^/ , and n are all integers of 1-10. The invention also discloses a method for preparing itaconic acid-aspartic acid copolymerized phosphorus-free scale inhibitor. The itaconic acid-aspartic acid copolymerized phosphorus-free scale inhibitor of the present invention introduces functional groups such as carboxyl groups and amide groups into the molecule, so that the polymer has excellent scale inhibition and dispersion properties for calcium carbonate; itaconic acid When the dosage of the water treatment agent copolymerized with aspartic acid is 14mg L ^‑1 , the scale inhibition rate to calcium carbonate is 96.4%, and the scale formed is soft and easily washed away by water, indicating that its dispersion performance is better . The preparation method of the itaconic acid-aspartic acid copolymerized phosphorus-free scale inhibitor of the present invention has easy-to-obtain raw materials for the synthesis of copolymers, mild reaction conditions, biodegradable copolymerized products, no phosphorus, and no impact on the environment, and the synthesis cost is low. The post-processing cost is low.

Description

Itaconic acid-aspartic acid copolymer non-phosphorus scale inhibitor and preparation method thereof

technical field

The invention belongs to the technical field of reverse osmosis membrane water treatment agents, in particular to itaconic acid-aspartic acid copolymerized phosphorus-free scale inhibitor and a preparation method thereof.

Background technique

In the reverse osmosis membrane separation water system, adding antiscalants is to prevent calcium carbonate, calcium phosphate and calcium sulfate and other insoluble salts from depositing on the membrane surface, resulting in shortened life of reverse osmosis membrane, shortened operation cycle and increased cost. effective method. However, most of the reverse osmosis membrane antiscalants currently used in China are imported products from companies such as King Lee and Betz Dearbobu, which are expensive. With the increasing application of reverse osmosis membrane desalination technology, it is of great significance to study high-efficiency reverse osmosis membrane scale inhibitors with independent intellectual property rights.

At present, the commonly used reverse osmosis membrane scale inhibitors at home and abroad mainly include polyphosphate, organic phosphonate, phosphine-containing polymers, acrylic acid and maleic acid polymers. Among them, phosphorus-containing scale inhibitors are easily hydrolyzed, causing eutrophication of water bodies, and causing a certain degree of environmental pollution. In addition, polyphosphate is a source of nutrients for microorganisms, which can promote the growth of bacteria and algae and aggravate the microbial contamination of reverse osmosis membranes. As global oil prices continue to rise, the price of acrylic acid, which is mainly produced from petroleum, continues to rise, causing the cost of polycarboxylate scale inhibitors with acrylic acid as the main monomer to continue to rise. The development of phosphorus-free, efficient and biodegradable green reverse osmosis antiscalants has become a hot spot in the field of antiscalant research.

Contents of the invention

Purpose of the invention: The purpose of the present invention is to provide itaconic acid-aspartic acid copolymerized non-phosphorus scale inhibitor. Another object of the present invention is to provide a preparation method of itaconic acid-aspartic acid copolymerized phosphorus-free scale inhibitor, the reaction conditions are mild, the copolymerization product is biodegradable, phosphorus-free, and environmentally friendly. impact, synthesis cost and post-processing cost are low.

In order to realize the above-mentioned purpose of the invention, the present invention adopts following technical scheme:

Itaconic acid-aspartic acid copolymer non-phosphorus scale inhibitor, itaconic acid and aspartic acid are copolymerized as monomers, and the general formula of the polymer is as follows:

In formula (I), m, m/, and n are all integers of 1-10.

The method for preparing itaconic acid-aspartic acid copolymer non-phosphorus scale inhibitor comprises the steps:

1) Add itaconic acid, aspartic acid, deionized water and catalyst to the reactor, heat in a constant temperature water bath, stir to dissolve itaconic acid and aspartic acid, and add a buffer to adjust the pH value of the solution , keeping the pH value at 8-9 to obtain a reaction solution;

2) Under a nitrogen atmosphere, maintain the temperature at 70-95°C, add the initiator dropwise to the reaction solution at a uniform speed, heat to reflux and stir mechanically, and continue the heat preservation reaction after the dropwise addition is completed;

3) After the reaction is finished, cool down and stop stirring to obtain itaconic acid-aspartic acid copolymerized non-phosphorus scale inhibitor.

In step 1), the reactor is a three-necked flask equipped with a reflux condenser, a constant pressure dropping funnel and a stirrer.

In step 1), the ratio of the amount of itaconic acid and aspartic acid is 1:1 to 5:1, the catalyst accounts for 6 to 12% of the mass sum of itaconic acid and aspartic acid, and the deionized water and aspartic acid The mass ratio of reactive monomers was 2.3. Wherein, the reactive monomers are monomers of itaconic acid and aspartic acid.

In step 1), the buffering agent is sodium hydroxide or potassium hydroxide.

In step 2), the dropping time of uniformly dropping the initiator is 0.5 h, and the reaction time of continuing to keep warm is 1-4 h.

In step 3), after the reaction is finished, cool down, stop stirring, and obtain a polymerization reaction product solution; add absolute ethanol to the polymerization reaction product solution, obtain a polymerization reaction product precipitation after stirring, vacuum-dry to constant weight, and obtain itacon Acid-aspartic acid copolymerized non-phosphorus scale inhibitor.

The principle of the invention: itaconic acid and aspartic acid are used as polymerization monomers, and the aqueous solution free radical polymerization method is adopted, the temperature is easy to control, the polymerization concentration in the system is relatively low, and it is inconvenient to carry out the transfer of chain free radicals to macromolecules, resulting in branching or cross-linked products. Moreover, the aqueous solution radical polymerization method is adopted. After the reaction, the product is very easy to transport and wash, and small molecular substances are easy to go out and impurities are easy to remove.

Both itaconic acid and aspartic acid are bio-fermentation products, non-toxic, and have a wide range of sources. Using itaconic acid and aspartic acid as monomers, they can be copolymerized into reverse osmosis membrane scale inhibitors, which can not only reduce production costs, but also Reducing the impact on the environment is conducive to promoting the application of reverse osmosis membrane technology in the field of water treatment, and has great significance for actual production.

Beneficial effects: Compared with the prior art, the itaconic acid-aspartic acid copolymerized phosphorus-free scale inhibitor of the present invention introduces functional groups such as carboxyl groups and amide groups into the molecule, so that the polymer has Excellent scale inhibition and dispersion performance; when the dosage of water treatment agent after copolymerization of itaconic acid and aspartic acid is 14mg·L ^-1 , the scale inhibition rate to calcium carbonate is 96.4%, and the scale formed is soft and easy to be Water washed away, indicating that its dispersion performance is better. The preparation method of the itaconic acid-aspartic acid copolymerized phosphorus-free scale inhibitor of the present invention has easy-to-obtain raw materials for synthesizing the copolymer, mild reaction conditions, biodegradable copolymerized products, no phosphorus, and no impact on the environment, and the synthesis cost is low. The post-processing cost is low and has good practicability.

Description of drawings

Fig. 1 is the infrared spectrogram of itaconic acid-aspartic acid copolymer;

Fig. 2 is the relation graph of the concentration of copolymer and to calcium carbonate scale inhibition rate;

Fig. 3 is the degradation rate when the mass concentration of the inoculum is 1g·L ^-1 and the mass concentration of the copolymer of the present invention is 300 mg·L ^-1 ;

Figure 4 shows the degradation rate when the mass concentration of the inoculum is 1 g·L ^-1 and the mass concentration of the copolymer of the present invention is 30 mg·L ^-1 .

detailed description

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

Figure 1 is the infrared spectrogram of itaconic acid-aspartic acid copolymer; analysis shows that the infrared spectrogram of the polymer does not appear C=C stretching in double bond olefins at 1680～1620cm ^-1 and 910～890cm ^-1 The vibration peak and the out-of-plane rocking vibration peak of =CH ₂ indicate that monomer IA has undergone copolymerization under certain polymerization conditions. 3370.09cm ^-1 is the stretching vibration peak of NH in amides, 1560.67cm ^-1 is the stretching vibration peak of C=O, 1391.63cm ^-1 is the stretching vibration peak of CN and the bending vibration peak of NH bond, and 1337.39cm ^-1 is the bending vibration peak of CN bond Vibration peaks indicate that the polymer product contains amide groups.

Example 1

In this embodiment, itaconic acid-aspartic acid copolymer is synthesized according to the following steps, and itaconic acid and aspartic acid monomers are added into a three-necked flask as raw materials, and the amount of itaconic acid and aspartic acid The ratio is 1:1 or 3:2 or 4:1, the solvent is deionized water, and the mass ratio of deionized water to reactant monomer is 2.3. Put the flask into a constant temperature water bath adjusted to 75°C or 85°C or 95°C for heating, turn on the stirrer and stir to dissolve itaconic acid and aspartic acid, and oxidize it with 40% (mass fraction) of hydrogen The sodium solution is neutralized to a pH of 8-9. Use a constant-pressure dropping funnel to add the initiator ammonium persulfate at a constant speed, the quality of ammonium persulfate is 7% or 9% or 11% of the total mass of itaconic acid and aspartic acid, nitrogen protection, heating to reflux and mechanical stirring, drop The adding time is 0.5h. After the dropwise addition is completed, continue the heat preservation reaction for 2h or 3h or 4h. Cooling, stop stirring, obtain the product itaconic acid-aspartic acid copolymer solution of the present invention, can obtain light yellow, yellow, reddish-brown product under different conditions. Add an appropriate amount of absolute ethanol to the mixed system of the polymerization reaction product, stir, and refine to obtain the precipitate of the product of the present invention, vacuum-dry to constant weight, and measure the solid content of the product of the present invention, and the solid content is 29.6-32.1. The itaconic acid-aspartic acid copolymer was synthesized according to the monomer ratio listed in Table 1, the amount of initiator, the reaction temperature and the reaction time, and the static scale inhibition method was used to evaluate the scale inhibition performance of the product to calcium carbonate obtained under different conditions. , the research results are listed in Table 1.

In this synthesis process, the most suitable pH range of the reaction solution is 8-9. When the pH of the reaction solution was 6, the upper layer of the product obtained after the reaction was a brownish-yellow clear liquid, and the lower layer was a white powdery solid, and the itaconic acid-aspartic acid copolymer of the present application could not be obtained. When the reaction solution was neutralized to a stronger alkalinity with 40% (mass fraction) of the sodium hydroxide solution, a brownish-red liquid was obtained, and this liquid gave out the smell of ammonia, and the product obtained under this condition had a certain resistance to calcium carbonate Anti-scaling effect but relatively poor anti-scaling performance.

Table 1 Antiscalant properties of products synthesized with different monomer ratios, initiator dosage, reaction temperature and reaction time

serial number monomer ratio Initiator dosage temperature reflex Reaction time Product scale inhibition rate (%) 1 1:1 7% 75°C 2 hours 40.2 2 1:1 9% 85°C 3 hours 59.4 3 1:1 11% 95°C 4 hours 15.2 4 3:2 7% 85°C 4 hours 48.9 5 3:2 9% 95°C 2 hours 55.1 6 3:2 11% 75°C 3 hours 30.5 7 4:1 7% 95°C 3 hours 48.4 8 4:1 9% 75°C 4 hours 37.1 9 4:1 11% 85°C 2 hours 64.9 10 4:1 9% 85°C 2 hours 68.5

The static scale inhibition method was used to evaluate the scale inhibition performance of the itaconic acid-aspartic acid copolymer produced in Example 1 on calcium carbonate, and this method was adopted unless otherwise specified. The test conditions are as follows: temperature: 80°C; dosing concentration: 10mg·L ^-1 ; test time: 10h; test configuration water: Ca ²⁺ 250mg·L ^-1 , HCO ₃ ^- 250mg·L ^-1 (both CaCO ₃ Calculated), the concentration factor is 1.5 times; at the same time, do a blank test without adding medicament. It can be seen from Table 1 that under the reaction conditions of No. 10, the scale inhibition rate of the product reaches 68.5%.

Embodiment 2 Add itaconic acid and aspartic acid monomers as raw materials in a three-necked flask, and get the raw materials according to the ratio of the amount of itaconic acid and aspartic acid listed in Table 2, and the solvent is deionized water , the mass ratio of deionized water to reactant monomer is 2.3, put the flask into a constant temperature water bath adjusted to 85°C for heating, turn on the stirrer and stir to dissolve itaconic acid and aspartic acid, and use 40% (mass fraction) sodium hydroxide solution to neutralize to pH 8-9. Use a constant pressure dropping funnel to add the initiator ammonium persulfate at a constant speed. The mass of ammonium persulfate is 9% of the total mass of the monomer. Under nitrogen protection, heat to reflux and stir mechanically. The dropping time is 0.5h. After the dropping is completed, continue Insulation reaction 2h. Cool, stop stirring, and obtain the product itaconic acid-aspartic acid copolymer solution of the present invention. The results of the research on the scale inhibition performance of the copolymerized products on calcium carbonate are listed in Table 2.

Table 2 The effect of the ratio of the amount of itaconic acid and aspartic acid on the scale inhibition performance of the copolymerization product

The ratio of the amount of itaconic acid to aspartic acid Scale inhibition rate 1:1 49.3 2:1 34.7 3:1 38.9 4:1 68.5 5:1 59.1

Example 3

Add 12.74g (0.098mol) of itaconic acid and 3.26g (0.025mol) of aspartic acid into the three-necked flask, the solvent is deionized water, and the mass ratio of deionized water to reactant monomer is 2.3. The flask is put into a constant temperature water bath adjusted to a certain temperature for heating, the temperature of the water bath is set according to the data in Table 3, the stirrer is turned on and stirred to dissolve itaconic acid and aspartic acid, and use 40% ( mass fraction) of sodium hydroxide solution to neutralize to a pH of 8-9. Use a constant pressure dropping funnel to add the initiator ammonium persulfate at a constant speed. The mass of ammonium persulfate is 9% of the total mass of the monomer. Under nitrogen protection, heat to reflux and stir mechanically. The dropping time is 0.5h. After the dropping is completed, continue Insulation reaction 2h. Cool, stop stirring, and obtain the product itaconic acid-aspartic acid copolymer solution of the present invention. The research results of the scale inhibition performance of the copolymerized products on calcium carbonate are listed in Table 3.

Table 3 The effect of copolymerization temperature on the scale inhibition performance of the itaconic acid-aspartic acid copolymerization product

Copolymerization temperature (℃) Scale inhibition rate 70 37.6 75 49.3 80 58.8 85 68.5 90 58.4

Example 4

Add 12.74g (0.098mol) of itaconic acid and 3.26g (0.025mol) of aspartic acid into the three-necked flask, the solvent is deionized water, and the mass ratio of deionized water to reactant monomer is 2.3. Put the flask into a constant temperature water bath adjusted to 85°C for heating, turn on the stirrer to stir, dissolve itaconic acid and aspartic acid, and neutralize it to pH with 40% (mass fraction) sodium hydroxide solution 8 to 9. Use a constant pressure dropping funnel to drop the initiator ammonium persulfate at a constant speed, take different qualities of ammonium persulfate according to Table 4, protect with nitrogen, heat to reflux and mechanically stir, the dropping time is 0.5h, after the dropping is completed, continue the insulation reaction 2h. Cool, stop stirring, and obtain the product itaconic acid-aspartic acid copolymer solution of the present invention. The research results of the scale inhibition performance of the copolymerized products on calcium carbonate are listed in Table 4.

Table 4 Influence of the amount of initiator on the scale inhibition performance of the itaconic acid-aspartic acid copolymerization product

Initiator mass accounted for total monomer mass% Scale inhibition rate 6 44.1 8 51.2 9 68.5 10 63.0 12 62.4

Example 5

Add 12.74g (0.098mol) of itaconic acid and 3.26g (0.025mol) of aspartic acid into the three-necked flask, the solvent is deionized water, and the mass ratio of deionized water to reactant monomer is 2.3. Put the flask into a constant temperature water bath adjusted to 85°C for heating, turn on the stirrer to stir, dissolve itaconic acid and aspartic acid, and neutralize it to pH with 40% (mass fraction) sodium hydroxide solution 8 to 9. Use a constant pressure dropping funnel to add the initiator ammonium persulfate at a constant speed. The mass of ammonium persulfate is 9% of the total mass of the monomer. Under nitrogen protection, heat to reflux and stir mechanically. The dropping time is 0.5h. After the dropping is completed, continue For the heat preservation reaction, set the time for continuing the heat preservation reaction according to Table 5. Cool, stop stirring, and obtain the product itaconic acid-aspartic acid copolymer solution of the present invention. The research results of the scale inhibition performance of the copolymerized products on calcium carbonate are listed in Table 5.

Table 5 Effect of reaction time on the scale inhibition performance of the itaconic acid-aspartic acid copolymer product

Reaction time (h) Scale inhibition rate 1.0 57.7 1.5 58.3 2.0 68.5 2.5 68.8 3.0 68.9

Example 6

Adopt static antiscaling method to research dosing concentration to the influence of itaconic acid-aspartic acid copolymer on calcium carbonate scale inhibition performance, itaconic acid-aspartic acid copolymer is taken from test 10 in the table 1 of embodiment 1 Synthetic product of the synthetic product, the test conditions are as follows: temperature: 70 ℃, dosing concentration is 1, 2, 4, 6, 8, 10, 12, 14, 16, 18 and 20 mg·L ^-1 See Figure 2 for the relationship between the drug concentration and the scale inhibition rate of calcium carbonate.

Analyzing Figure 2, it can be seen that with the increase of dosing concentration, the scale inhibition efficiency of the copolymerization product on calcium carbonate gradually increases, and when the dosing amount of the medicament is 14mg·L ^-1 , the scale inhibition rate on calcium carbonate can reach 96.4%. The scale inhibition efficiency increases slowly when the chemical concentration is increased.

Example 7

The biodegradability of the itaconic acid-aspartic acid polymer produced in Test 10 in Table 1 of Example 1 was evaluated by the bioshaker method. The test conditions are as follows: temperature: 25°C, oscillation frequency 120r·min ^-1 ; dosing concentration is 300mg·L ^-1 , 30mg·L ^-1 , inoculum mass concentration is 1g·L ^-1 , and test time is respectively: 0, 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29d; Nutrient composition: CaCl ₂ 110.00mg·L ^-1 , MgSO ₄ 44.00mg· L ^-1 , FeCl ₃ 1.20mg·L ^-1 , (NH ₄ ) ₂ SO ₄ 160.00mg·L ^-1 , 2mL phosphate buffer solution (pH value is about 7.5); at the same time, do a blank test without adding medicine. The test results are shown in Figure 3 and Figure 4.

It can be seen from Figure 3 that when the concentration of the agent measured by this method is 300 mg·L ^-1 , the degradation rate is relatively low in the first 10 days, and it is in the acclimatization period; it can reach more than 60% in the 19th day, although the degradation rate in the later period cannot reach 100%, but Basically met the requirement of biodegradability.

It can be seen from Fig. 4 that when the concentration of the drug measured by this method is 30 mg·L ^-1 , the degradation rate is close to 60% in the first 10 days; it can reach more than 80% in the 19th day, and the degradation rate is more than 90% in the later period, which is relatively close to 100% % completely degraded, it can be seen that the biodegradability of the itaconic acid-aspartic acid polymer is very good, and it belongs to the environment-friendly reverse osmosis membrane scale inhibitor.

Claims (7)

1. Itaconic acid-aspartic acid copolymer non-phosphorus scale inhibitor is characterized in that: it is formed by copolymerization of itaconic acid and aspartic acid as monomers, and the general formula of the polymer is as follows: In formula (I), m, m/, and n are all integers of 1-10. 2. prepare the method for itaconic acid-aspartic acid copolymerization non-phosphorus scale inhibitor described in claim 1, it is characterized in that: comprise the steps: 1) Add itaconic acid, aspartic acid, deionized water and catalyst to the reactor, and heat it in a constant temperature water bath, the temperature of the water bath is 70-95°C, stir to make itaconic acid and aspartic acid Dissolving the acid, adding a buffer to adjust the pH value of the solution, keeping the pH value at 8-9, and obtaining a reaction solution; 2) Under a nitrogen atmosphere, maintain the temperature at 70-95°C, add the initiator dropwise to the reaction solution at a uniform speed, heat to reflux and stir mechanically, and continue the heat preservation reaction after the dropwise addition is completed; 3) After the reaction is finished, cool down and stop stirring to obtain itaconic acid-aspartic acid copolymerized non-phosphorus scale inhibitor. 3. the preparation method of itaconic acid-aspartic acid copolymerization non-phosphorus scale inhibitor according to claim 2 is characterized in that: in step 1), described reactor is equipped with reflux condenser, constant pressure Three-neck flask with dropping funnel and stirrer. 4. the preparation method of itaconic acid-aspartic acid copolymer non-phosphorus scale inhibitor according to claim 2 is characterized in that: in step 1), the ratio of the amount of substance of itaconic acid and aspartic acid The ratio is 1:1-5:1, the catalyst accounts for 6-12% of the total mass of itaconic acid and aspartic acid, and the mass ratio of deionized water to reactant monomer is 2.3. 5. The preparation method of itaconic acid-aspartic acid copolymerized non-phosphorus scale inhibitor according to claim 2, characterized in that: in step 1), the buffering agent is sodium hydroxide or potassium hydroxide. 6. the preparation method of itaconic acid-aspartic acid copolymerization non-phosphorus scale inhibitor according to claim 2 is characterized in that: in step 2), the dripping time of uniform dripping initiator is 0.5h, continues The heat preservation reaction time is 1 to 4 hours. 7. the preparation method of itaconic acid-aspartic acid copolymerization non-phosphorus scale inhibitor according to claim 2 is characterized in that: in step 3), after described reaction finishes cooling, stop stirring, obtain polymerization reaction Product solution: adding absolute ethanol to the polymerization product solution, stirring to obtain the precipitation of the polymerization product, vacuum drying to constant weight, and obtaining itaconic acid-aspartic acid copolymerized non-phosphorus scale inhibitor.