CN111748057A - A kind of method for synthesizing gum arabic high polymer by composite initiation system - Google Patents

Abstract

The invention discloses a method for synthesizing gum arabic high polymer through a composite initiation system. In this method, gum arabic and acrylamide (AM) are used as raw materials; gum arabic is dissolved in distilled water to prepare an aqueous solution, and the pH value of the solution is adjusted under constant temperature; after being packed in a vacuum-sealed bag, high hydrostatic pressure technology is used for gelation treatment, and then sonicated to obtain gum arabic nanoparticles. Add AM and distilled water, and homogenize the mixture with an ultra-high-speed homogenizer; add photoinitiator azobisisobutylimidazoline hydrochloride (VA‑044) and thermal initiator cerium amine nitrate (CAN), nitrogen After the oxygen drive is sealed, the reactor is put into a transparent incubator, irradiated with an ultraviolet lamp, and the polymerization reaction is initiated by photothermal synergistic initiation. The gum arabic high polymer obtained by the invention has high conversion rate and is a high-efficiency polymer in water treatment applications.

Description

A kind of method for synthesizing gum arabic high polymer by composite initiation system

technical field

The invention belongs to the technical field of flocculants, in particular to a method for synthesizing gum arabic high polymer through a composite initiation system.

Background technique

The coagulation method is widely used in water treatment because of its simplicity, economy and high efficiency. In the coagulation experiment, the main role is the flocculant, which is an indispensable chemical agent in the treatment of domestic water and wastewater, and an important environmental ecological material. Pollution control and other fields play an important role. In the process of water treatment, it mainly plays the role of adsorption electric neutralization, compressing the electric double layer, adsorption, bridging and so on. Flocculants mainly include inorganic flocculants, organic polymer flocculants, natural organic polymer flocculants and microbial flocculants.

Gum arabic is a natural polysaccharide with good solubility, emulsification, stability and environmental friendliness, and can be used in many industrial fields. In recent years, it has also received extensive attention in the field of environmental engineering, but the effect of gum arabic in environmental pollution treatment is not very significant. In order to improve the flocculation effect of gum arabic, a certain method can be used to make gum arabic molecules into nanoparticles. And carry out targeted modification to improve its physical and chemical properties. At present, there are few studies on this aspect.

Chinese patent application number CN201510001967.6, the title of the invention is "a preparation method of nanoparticle with photothermal effect and its application", which discloses a kind of using chitosan and other positively charged molecules in reverse microemulsion using Beijing Nipin initiates the polymerization reaction, then the surface is modified with PEG to enhance biocompatibility, and finally, the photothermal conversion material is supported by positive and negative charges to prepare nanoparticles with significant photothermal effect. The nanoparticle has strong photothermal killing ability, but the preparation process is complicated, and the addition of a cross-linking agent will cause certain pollution to the nanoparticle.

Chinese Patent Application No. CN201810562808.7, the name of the invention is "a preparation method of acacia hollow nanospheres", which discloses a method of first preparing short amyloid chains of starch by biological enzymatic method, and adding gum arabic to it to form starch nanoparticles , and then use α# amylase to hydrolyze starch to obtain acacia hollow nanospheres. It has the advantages of low equipment requirements, mild reaction, etc., but the preparation process is cumbersome, and the flocculation and sedimentation performance of the obtained product is not good, resulting in an unsatisfactory treatment effect.

SUMMARY OF THE INVENTION

In view of the above-mentioned deficiencies in the prior art, the present invention provides a gum arabic high polymer synthesized by a composite initiation system with simple process and stable product performance.

In order to achieve the above object, the technical scheme adopted in the present invention is as follows:

Using gum arabic and acrylamide (AM) as raw materials; dissolving gum arabic in distilled water, making into an aqueous solution after complete dissolution, and adjusting the pH value of the solution under constant temperature conditions; packaging in a vacuum-sealed bag and placing it in high hydrostatic pressure (HHP ) In the medium (water) of the cylinder of the equipment, the high hydrostatic pressure technology is used to gel the gum arabic, and then the gum arabic nanoparticles are obtained by ultrasonic treatment. AM and distilled water were added to the obtained nanoparticles, and the mixture was homogenized with an ultra-high-speed homogenizer to obtain a colloidal dispersion whose particle concentration was the concentration of gum arabic before gelation; a photoinitiator, azobisisobutimidazole, was added. Phosphate hydrochloride (VA-044) and thermal initiator ceric amine nitrate (CAN), and use nitrogen to drive oxygen. After sealing, the reactor was placed in a transparent incubator, and irradiated with a UV lamp. Photothermal synergistic initiation was used to initiate the After the polymerization reaction, curing and purification, a gum arabic high polymer synthesized by the composite initiation system is obtained.

Specifically include the following steps:

1) Put the gum arabic in distilled water, and after it is completely dissolved, prepare an aqueous solution of gum arabic with a concentration of 10~15%, and adjust the pH value of the solution under constant temperature conditions.

2) Pack the solution in a vacuum-sealed bag and put it into the medium (water) of a high hydrostatic pressure (HHP) equipment cylinder of 600~800Mpa for a period of time, and use the high hydrostatic pressure technology to gel the gum arabic to obtain gum arabic Gum, and then ultrasonically treated to obtain gum arabic nanoparticles. When the induction pressure is lower than 600Mpa, it is not enough to induce gum arabic into a gel. When the pressure is higher than 800Mpa, the molecular bonds of gum arabic are easily broken and will not be gelled.

3) An appropriate amount of acrylamide and distilled water are added to the obtained nanoparticles, and the mixture is homogenized with an ultra-high-speed homogenizer to obtain a colloidal dispersion whose particle concentration is the concentration of gum arabic before gelation. The mass ratio of gum arabic to AM in the nanoparticles was 1~1.5:1. When the ratio is lower than 1:1, self-polymerization and cross-linking between AM monomers is easy to occur, which is not conducive to grafting to Gum Arabic nanoparticles. When the ratio is higher than 1.5:1, the number of nanoparticles is too large, and the water solubility of the prepared polymer samples is extremely poor.

4) Add 0.2~0.6% photoinitiator azobisisobutylimidazoline hydrochloride (VA-044) and thermal initiator cerium amine nitrate (CAN) in a ratio of 1~1.5:1, and use nitrogen to drive oxygen. When the initiator concentration is lower than 0.2%, the number of decomposed free radicals is low, and the reaction sites on acrylamide and nanoparticles cannot be activated, resulting in a reduction in the probability of active groups participating in the reaction, so that the graft copolymerization product is either quantitative or The length ratio of the molecular chain is reduced, resulting in a low viscosity of the entire reaction system. When the initiator concentration is higher than 0.6%, the viscosity of the reaction system has reached a certain threshold, and the solubility of gel nanoparticles and monomers in the reaction system has decreased. At this time, the grafting reaction no longer dominates, and the homopolymerization reaction An increase will result in a decrease in product and a decrease in molecular weight.

5) After sealing the reactor, put it into a transparent incubator at 40~60°C, and irradiate it with an ultraviolet lamp at the same time. The polymerization reaction is initiated by photothermal synergistic initiation. of gum arabic polymers. At a constant temperature of 40 °C, the monomer activity and radical movement and diffusion rates are low, so the reaction rate is low. AM molecules cannot adequately bind to the active sites of gum arabic nanoparticles. When the temperature exceeds 70 °C, the active center of the nanoparticles becomes very unstable, and the heat released by the polymerization reaction cannot be dissipated in time, resulting in chain transfer and chain termination, which reduces the grafting efficiency.

Among them: the pH value in step 1) should be adjusted to 6.5~7.5 under the constant temperature of 25~30℃.

The gum arabic is a natural polymer material and is widely distributed in nature. It is composed of polysaccharides and protein structures with high relative molecular weight, and the molecular weight ranges from hundreds of thousands to several million; it is widely distributed in nature and has good adsorption, low toxicity and environmental friendliness.

In step 2), the gelation time is 30~45min, and the ultrasonic treatment time is 1~3min. When the time is less than 30min, the polycondensation reaction is incomplete, and the gum arabic cannot be completely polycondensed into a gel. After the time reaches 45min, the gelation has been completed, and increasing the time has little effect.

The time of homogenization in step 3) is 3~5min, and the rotating speed is 6000~8000r/min. When the rotation speed exceeds 8000 r/min, it is easy to cause the gradual dissociation of ground state molecules and atoms, and the number of active groups gradually decreases.

The photothermal synergistic initiation time in step 5) is 1~2h. Before the polymerization time is 1 hour, the residual free radicals are not completely consumed, and the grafting efficiency is not very high. After the polymerization time reaches 2 hours, the polymerization reaction between the monomers has been completed. No effect.

Compared with the prior art, the present invention has the following beneficial effects:

1. The preparation method of the present invention has the advantages of stable reaction, easy control and few side reactions, and the obtained gum arabic polymer synthesized by the composite initiation system has high molecular weight and good water solubility.

2. The present invention adopts the method of making gum arabic into nanoparticles, and then carries out graft copolymerization with monomer acrylamide, which greatly improves the removal rate of dissolved organic matter, and the removal rate is stable at more than 90%.

3. Compared with other polymers, the gum arabic high polymer synthesized by the composite initiation system prepared by the present invention has a higher conversion rate, which is more conducive to the settlement of flocs during the flocculation process, and can not only be used for dissolved organic matter , The treatment of oily wastewater, its pH applicable range, complexing ability, salt resistance and other water treatment performance have been significantly enhanced. Therefore, the gum arabic polymer synthesized by the composite initiation system has good social and economic benefits in practical applications.

Detailed ways

The present invention will be described in further detail below in conjunction with specific embodiments. Unless otherwise specified in the embodiments, the raw materials used are common commercially available products.

Example 1:

The gum arabic polymer synthesized by the composite initiation system was prepared in the following manner:

1) Weigh a certain amount of gum arabic and put it in distilled water, stir until the gum arabic is completely dissolved to obtain a gum arabic solution with a concentration of 10%, and adjust the pH value of the solution to 7 at a constant temperature of 25 °C.

2) Pack the solution in a vacuum-sealed bag and put it into the medium (water) of a 600Mpa high hydrostatic pressure (HHP) equipment cylinder for 45 minutes, and use the high hydrostatic pressure technology to gel the gum arabic to obtain gum arabic gel, and then Gum arabic nanoparticles were obtained by sonication for 3 min.

3) Add an appropriate amount of acrylamide and distilled water to the obtained nanoparticles, and homogenize the mixture with an ultra-high-speed homogenizer with a rotating speed of 60,000 r/min for 3 minutes to obtain a colloidal dispersion with the particle concentration of the gum arabic before gelation. The mass ratio of gum arabic to AM in the nanoparticles was 1:1.

4) Add 0.2% photoinitiator azobisisobutylimidazoline hydrochloride and thermal initiator ceric amine nitrate in a ratio of 1:1, and use nitrogen to drive oxygen.

5) After sealing, put the reactor into a transparent incubator at 60°C, and irradiate it with an ultraviolet lamp. The polymerization reaction is initiated by photothermal synergistic initiation for 1 hour. polymer.

Example 2:

The gum arabic polymer synthesized by the composite initiation system was prepared in the following manner:

1) Weigh a certain amount of gum arabic and put it in distilled water, stir until the gum arabic is completely dissolved to obtain a gum arabic solution with a concentration of 10%, and adjust the pH of the solution to 7.5 at a constant temperature of 25 °C.

2) Pack the solution in a vacuum-sealed bag and put it into the medium (water) of an 800Mpa high hydrostatic pressure (HHP) equipment cylinder for 30 minutes, and use high hydrostatic pressure technology to gel the gum arabic to obtain gum arabic gel, and then Gum arabic nanoparticles were obtained by sonication for 1 min.

3) Add an appropriate amount of acrylamide and distilled water to the obtained nanoparticles, and homogenize the mixture with an ultra-high-speed homogenizer with a rotating speed of 60,000 r/min for 3 minutes to obtain a colloidal dispersion with the particle concentration of the gum arabic before gelation. The mass ratio of gum arabic to AM in the nanoparticles was 1.5:1.

4) Add 0.6% photoinitiator azobisisobutylimidazoline hydrochloride and thermal initiator ceric amine nitrate in a ratio of 1:1, and use nitrogen to drive oxygen.

5) After sealing, put the reactor into a transparent incubator at 60°C, and irradiate it with an ultraviolet lamp. The polymerization reaction is initiated by photothermal synergistic initiation for 2 hours. polymer.

Example 3:

The gum arabic polymer synthesized by the composite initiation system was prepared in the following manner:

1) Weigh a certain amount of gum arabic and put it in distilled water, stir until the gum arabic is completely dissolved to obtain a gum arabic solution with a concentration of 15%, and adjust the pH value of the solution to 7 at a constant temperature of 30 °C.

2) Pack the solution in a vacuum-sealed bag and put it into the medium (water) of a 600Mpa high hydrostatic pressure (HHP) equipment cylinder for 45 minutes, and use the high hydrostatic pressure technology to gel the gum arabic to obtain gum arabic gel, and then Gum arabic nanoparticles were obtained by sonication for 1 min.

3) Add an appropriate amount of acrylamide and distilled water to the obtained nanoparticles, and homogenize the mixture with an ultra-high-speed homogenizer with a rotating speed of 80,000 r/min for 5 minutes to obtain a colloidal dispersion with a particle concentration of the gum arabic before gelation. The mass ratio of gum arabic to AM in the nanoparticles was 1.5:1.

4) Add 0.6% photoinitiator azobisisobutylimidazoline hydrochloride and thermal initiator ceric amine nitrate in a ratio of 1.5:1, and use nitrogen to drive oxygen.

5) After sealing, put the reactor into a transparent incubator at 40°C, and irradiate it with an ultraviolet lamp. The polymerization reaction is initiated by photothermal synergistic initiation for 2 hours. polymer.

Example 4:

The gum arabic polymer synthesized by the composite initiation system was prepared in the following manner:

1) Weigh a certain amount of gum arabic and put it in distilled water, stir until the gum arabic is completely dissolved to obtain a gum arabic solution with a concentration of 15%, and adjust the pH value of the solution to 6.5 at a constant temperature of 30 °C.

2) Pack the solution in a vacuum-sealed bag and put it into the medium (water) of an 800Mpa high hydrostatic pressure (HHP) equipment cylinder for 45 minutes, and use the high hydrostatic pressure technology to gel the gum arabic to obtain gum arabic gel. Gum arabic nanoparticles were obtained by sonication for 1 min.

3) Add an appropriate amount of acrylamide and distilled water to the obtained nanoparticles, and homogenize the mixture with an ultra-high-speed homogenizer with a rotating speed of 60,000 r/min for 5 minutes to obtain a colloidal dispersion with the particle concentration of the gum arabic before gelation. The mass ratio of gum arabic to AM in the nanoparticles was 1:1.

4) Add 0.2% photoinitiator azobisisobutylimidazoline hydrochloride and thermal initiator ceric amine nitrate in a ratio of 1.5:1, and use nitrogen to drive oxygen.

5) After sealing, put the reactor into a transparent incubator at 60°C, and irradiate it with an ultraviolet lamp. The polymerization reaction is initiated by photothermal synergistic initiation for 2 hours. polymer.

Example 5:

The gum arabic polymer synthesized by the composite initiation system was prepared in the following manner:

1) Weigh a certain amount of gum arabic and put it in distilled water, stir until the gum arabic is completely dissolved to obtain a gum arabic solution with a concentration of 10%, and adjust the pH of the solution to 6.5 at a constant temperature of 25 °C.

2) Pack the solution in a vacuum-sealed bag and put it into the medium (water) of a 600Mpa high hydrostatic pressure (HHP) equipment cylinder for 30 minutes. Use high hydrostatic pressure technology to gel the gum arabic to obtain gum arabic gel. Gum arabic nanoparticles were obtained by sonication for 3 min.

3) Add an appropriate amount of acrylamide and distilled water to the obtained nanoparticles, and homogenize the mixture with an ultra-high-speed homogenizer with a rotating speed of 80,000 r/min for 3 minutes to obtain a colloidal dispersion with the particle concentration of the gum arabic before gelation. The mass ratio of gum arabic to AM in the nanoparticles was 1:1.

4) Add 0.6% photoinitiator azobisisobutylimidazoline hydrochloride and thermal initiator ceric amine nitrate in a ratio of 1:1, and use nitrogen to drive oxygen.

5) After sealing, put the reactor into a transparent incubator at 40°C, and irradiate it with an ultraviolet lamp. The polymerization reaction is initiated by photothermal synergistic initiation for 2 hours. polymer.

The relevant properties of the gum arabic polymers synthesized by the composite initiation system prepared in Examples 1 to 5 were measured respectively, and the data are shown in Table 1.

Table 1 Properties of gum arabic polymers synthesized by composite initiation system

product Molecular weight (kDa) Removal rate of dissolved organic matter (%) Example 1 3639.3 96.7 Example 2 3122.3 94.3 Example 3 3444.6 95.8 Example 4 2795.4 91.9 Example 5 3101.1 93.3

As can be seen from the above table 1, the gum arabic polymer synthesized by the composite initiation system obtained by the present invention has a relatively large molecular weight, and the treatment effect on dissolved organic matter is also good, which proves that the gum arabic polymer synthesized by the composite initiation system Polymers have good properties.

The above-mentioned embodiments of the present invention are only examples for illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those of ordinary skill in the art, many changes in different forms can be made on the basis of the above description. Not all implementations can be exhaustive here. Any obvious changes or changes derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims (3)

1. a method for synthesizing gum arabic high polymer by composite initiation system, it is characterized in that, take gum arabic, acrylamide (AM) as raw material; Aqueous solution, and adjust the pH value of the solution under constant temperature conditions; after packaging in a vacuum-sealed bag, put it into the medium (water) of the cylinder of a high hydrostatic pressure (HHP) equipment of 600~800Mpa, and use high hydrostatic pressure technology to gel Arabic gum 30~45min, and then ultrasonically treated for 1~3min to obtain gum arabic nanoparticles. AM and distilled water were added to the obtained nanoparticles, the mass ratio of gum arabic to AM was 1~1.5:1, and the mixture was homogenized with an ultra-high-speed homogenizer with a rotating speed of 6000~8000 r/min to obtain the particle concentration It is a colloidal dispersion of gum arabic concentration before gelation; adding 0.2~0.6% photoinitiator azobisisobutylimidazoline hydrochloride (VA-044) and thermal initiator cerium nitrate in a ratio of 1~1.5:1 amine (CAN), and use nitrogen to drive oxygen. After sealing, put the reactor into a transparent incubator at 40~60°C, and irradiate it with an ultraviolet lamp. The polymerization reaction is initiated by photothermal synergistic initiation for 1~2h. After curing and purification, it is A gum arabic high polymer synthesized by a complex initiation system was obtained. 2 . The method for synthesizing a gum arabic high polymer by a composite initiation system according to claim 1 , wherein after the gum arabic is dissolved, the pH value of the solution is adjusted to be 6.5-7.5 at a constant temperature of 25-30° C. 3 . 3. a kind of method for synthesizing gum arabic high polymer by composite initiation system according to claim 1, is characterized in that, ultra-high-speed homogenizer carries out homogenization treatment time to mixture is 3～5min.