CN108892798B

CN108892798B - Preparation method of intelligent polymer embedded particles

Info

Publication number: CN108892798B
Application number: CN201810777849.8A
Authority: CN
Inventors: 万琼; 蒋志强; 张新艳; 鞠恺; 谷拴成; 赵志啸
Original assignee: Xian University of Science and Technology
Current assignee: Xian University of Science and Technology
Priority date: 2018-07-16
Filing date: 2018-07-16
Publication date: 2021-03-16
Anticipated expiration: 2038-07-16
Also published as: CN108892798A

Abstract

The invention relates to a polymer embedded particle with temperature and pH dual intelligent response and a preparation method thereof. The preparation steps of the embedded particles comprise: 1) calcium alginate is used as an embedding inner core; 2) the temperature-sensitive high polymer material acrylic acid and the pH-sensitive high polymer material isopropyl acrylamide are combined to the surface of the inner core through graft copolymerization to form an intelligent sensitive high polymer gel layer, so that intelligent high polymer embedded particles with double sensitivity to temperature and pH value are formed. Compared with the prior embedding technology, the embedded particles prepared by the invention have good biocompatibility and high mechanical strength, can enhance the tolerance capability of microorganisms to temperature and pH value fluctuation, effectively control the transfer and exchange of substances, and provide a stable environment for the growth, metabolism, culture and enrichment of microorganisms.

Description

Preparation method of intelligent polymer embedded particles

Technical Field

The invention belongs to the technical field of polymer composite materials, and particularly relates to a preparation method of intelligent polymer embedded particles.

Background

At present, sewage treatment plants at home and abroad also adopt an activated sludge method as a leading treatment process, and the process has the following problems: first, the share of the various microorganisms in the system is naturally formed by the substrate and the productivity of the microorganisms. Because the metabolism process of the autotrophic bacteria is slow, the growth period is long, and in the conventional activated sludge process, the relative autotrophic bacteria account for extremely low proportion, the relative pollutant removal efficiency is low, and the method becomes a controllable step in the sewage treatment technology. The nitrifying bacteria in the municipal sewage treatment plant are taken as an example for explanation. The concentrations of COD and ammonia nitrogen in the municipal sewage are generally 300-500 mg/L and 30-50 mg/L respectively, the sludge yield coefficients of corresponding heterotrophic bacteria and nitrifying bacteria are 0.2(gVSS/gCOD) and 0.1(gVSS/gNH4+ -N) respectively, and the shares of the corresponding heterotrophic bacteria and nitrifying bacteria in the activated sludge are 70-80% and 3-5% respectively. Although the nutrient conditions and operating conditions of the sewage treatment systems in various cities vary, the approximate ranges are substantially similar. Due to the low proportion of nitrifying bacteria, the removal rate of ammonia needs to be increased by prolonging the hydraulic retention time. Secondly, the sludge ages of different microorganisms in the same sewage treatment system are the same, but the sludge age is not the optimal residence time of various microorganisms, so that the treatment effect of the microorganisms cannot be optimal. Finally, the microorganisms in the sewage biological treatment are influenced by temperature and pH value, the influence on the autotrophic bacteria with small share under different temperature and pH value conditions is particularly obvious, and even the metabolic activity is stopped due to the fluctuation of the temperature and the pH value, so that the effluent of the system does not reach the standard.

The technique of embedding the target microorganism can effectively solve the above problems. As embedding materials, agar, carrageenan, chitosan, alginate, polyacrylamide (ACAM), polyvinyl alcohol (PVA), and the like are generally used. Agar is thermal gel, is not easy to be degraded by microorganisms, but has low mechanical strength and high price; carrageenan is a thermal/ionic gel containing potassium or calcium ions, and excess potassium ions are toxic to microbial cells during crosslinking. Chitosan is an anionic ionic gel that results in a decrease in microbial cell activity, mostly as a low concentration coating for microcapsules. The alginate is divalent ion gel, the condition for embedding microbial cells is simple and mild, the alginate is nontoxic, the biocompatibility is good, the cost is low, but the stability and the mechanical property of the colloidal beads are poor, and the colloidal beads are easily damaged or dissolved due to the influence of a cation chelating agent and an acidic environment. The polyacrylamide is a synthetic polymer, the hardness of the gel is influenced by the content of acrylamide and the content of embedded cells, the pore size and the stability of the gel are determined by the proportion of the acrylamide and a cross-linking agent, and the gel is very porous and has high water content. However, the cell viability is reduced because the reagents used and the free radical polymerization reactions often severely damage the cell wall. Polyvinyl alcohol (PVA) as a novel microorganism embedding immobilization carrier has higher mechanical strength and better chemical stability. However, researches show that the problems of high water swelling capacity, weak mass transfer capacity, serious damage of boric acid to microorganisms in the cross-linking embedding process and the like exist when PVA is used as an embedding and immobilizing carrier. According to the above documents, when the natural polymer is used for preparing the microbial cell particles, the preparation conditions are milder, the damage to the integrity and the activity of cells is small, the permeability is better, a better substance metabolism channel can be provided for microorganisms, but the mechanical strength is not enough, the chemical stability is poor, and the microorganisms are easy to break and leak. The artificially synthesized polymer can provide higher mechanical strength and chemical stability and strong biological decomposition resistance, but in the process of preparing the microcapsule, because the reaction conditions are too severe, the microbial cells are often seriously damaged, the cell activity is reduced, and the mass transfer effect is not as good as that of the natural polymer.

Disclosure of Invention

In order to overcome the disadvantages of the prior art, the present invention provides a method for preparing an intelligent polymer-embedded microparticle, which can immobilize target microorganisms in the microparticle under mild, non-toxic and biocompatible conditions, and allow the microbial metabolites to be transferred and exchanged with the environment through micropores in the microparticle, thereby realizing the metabolism, growth, reproduction and enrichment of microorganisms. The internal channels of the microparticles for metabolite transport and exchange have characteristics that vary with changes in temperature and pH. As the temperature decreases, the channel pore size increases. Generally, when the ambient temperature is reduced, the growth rate of the microorganism is reduced, and when the pore diameter of the channel is increased, the substrate transmission and exchange capacity is enhanced, so that the influence of temperature reduction on the growth and metabolism of the microorganism is reduced. As the pH increases, the channel pore size increases. Generally, when the concentration of some basic substrates is increased, the pH value is increased, the pore diameter of a channel is increased, the substrate transferring and exchanging capacity is enhanced, the degradation rate of the substrate by the microorganism is increased, and the influence on the growth and metabolism of the microorganism caused by the increase of the concentration of the substrate is reduced. The technology provides a stable environment for the growth metabolism, culture and enrichment of microorganisms, and weakens the impact of external environment change on the growth metabolism of the microorganisms. Meanwhile, as the microorganisms are fixed in the microspheres with larger particle sizes (1-5mm, different particle sizes are obtained by changing granulation conditions according to needs), the target microorganisms are easier to separate from the reaction system and recycle.

In order to achieve the purpose, the invention adopts the technical scheme that:

a preparation method of intelligent polymer embedded particles comprises the following steps:

(1) preparing a sodium alginate solution;

(2) preparing a calcium chloride solution;

(3) dripping the sodium alginate solution prepared in the step (1) into the calcium chloride solution prepared in the step (2) to prepare calcium alginate microspheres;

(4) preparing a temperature response solution;

(5) putting the calcium alginate microspheres prepared in the step (3) into the temperature response solution prepared in the step (4) to fully react to prepare temperature response microspheres;

(6) preparing a pH response solution;

(7) and (4) putting the temperature response microspheres prepared in the step (5) into the pH response solution prepared in the step (6) to perform full reaction to prepare the intelligent polymer embedded microspheres.

The mass concentration of the sodium alginate solution is 2-5%, the preparation temperature is 30-60 ℃, and the sodium alginate solution is fully dissolved at the temperature of DEG C.

The mass concentration of the calcium chloride solution is 1-6%.

And (3) dripping the calcium alginate microspheres with the height of 4-10cm into the solution, and storing the calcium alginate microspheres at low temperature for later use.

The temperature response solution in the step (4) comprises the following components: NIPPAm with mass concentration of 1-4%, MBA with mass concentration of 0.1-0.6 ‰, APS with mass concentration of 0.1-0.6 ‰, and TMEDA with volume concentration of 0.5-3 ‰.

And (5) putting the calcium alginate microspheres into a temperature response solution to perform a crosslinking reaction, wherein the reaction time is controlled within 1-4 h.

The pH response solution in the step (6) comprises the following components: AA with the mass concentration of 1-5 percent, MBA with the mass concentration of 0.1-0.6 thousandth, APS with the mass concentration of 0.1-0.6 thousandth and SBS with the mass concentration of 0.1-0.6 thousandth.

And (7) putting the temperature response microspheres into the pH response solution to react for 10-40min to obtain the dual-response intelligent polymer embedded microspheres, and then storing the dual-response intelligent polymer embedded microspheres in 1-6% calcium chloride solution.

Compared with the prior art, the invention uses alginate as the embedded inner core, and the conditions for embedding the microbial cells are simple and mild, non-toxic, good in biocompatibility and low in cost. On the basis, the temperature-sensitive high polymer material acrylic acid and the pH-sensitive high polymer material isopropyl acrylamide are combined to the surface of the inner core through graft copolymerization to form an intelligent sensitive high polymer gel layer, and finally intelligent high polymer embedded particles with double sensitivity to temperature and pH value are formed. The alginate used in the invention has good biocompatibility and low cost, and the polymer gel layer has an intelligent response function to temperature and pH value, and simultaneously, the polymer gel layer enhances the mechanical strength of the alginate pellets. The method has the advantages of realizing mild microorganism fixation, enhancing the tolerance of microorganisms to temperature and pH value fluctuation, realizing intelligent response of the microspheres to the temperature and the pH value, and enabling the mechanical strength of the microspheres to be higher and prolonging the service life through composite material granulation. Finally, the effective culture, enrichment and separation of different strains are realized. The microsphere can be applied to a fixed separation culture system of various microorganisms and a biological sewage treatment system of specific pollutants.

Drawings

FIG. 1 is a schematic diagram (40 times magnification) of the internal structure of temperature and pH dual-responsive microspheres obtained in example 1.

FIG. 2 is a schematic diagram (60 times magnification) of the internal structure of temperature and pH dual-responsive microspheres obtained in example 1.

FIG. 3 is a schematic diagram (5000 times magnified) of the internal structure of temperature and pH dual-responsive microspheres obtained in example 1.

FIG. 4 is a structural diagram (magnified 10000 times) of the internal structure of a temperature and pH dual-responsive microsphere obtained in example 1.

Figure 5 is a graph of blank calcium alginate, pH response, temperature response, and dual response microparticle infrared spectra.

Detailed Description

The embodiments of the present invention will be described in detail below with reference to the drawings and examples.

The invention relates to a preparation method of polymer embedded particles with dual intelligent responses of temperature and pH, wherein the required raw materials are shown in a table 1:

table 1: raw material table for preparing particles

The preparation method comprises the following steps:

(1) preparing a sodium alginate solution with the mass concentration of 2-5 percent: weighing a certain amount of sodium alginate powder, weighing a certain amount of deionized water according to the proportion that the mass percentage concentration is 2-5%, heating the mixture in a water bath to 30-60 ℃, adding the sodium alginate powder into the deionized water at 30-60 ℃, and continuously stirring the mixture by using a stirrer until the sodium alginate powder is completely dissolved for later use.

(2) Preparing a calcium chloride solution with the mass concentration of 1-6 percent: weighing a certain amount of calcium chloride, weighing a certain amount of deionized water according to the mass percentage concentration of 1-6%, adding the calcium chloride into the deionized water, and continuously stirring by using a stirrer until the calcium chloride is completely dissolved.

(3) Adding the corresponding solution into a granulator, dripping sodium alginate into calcium chloride solution, setting the rotating speed and dripping height of the granulator according to the requirement of the target microspheres, and preparing microspheres with the diameter of 1-5mm (prepared according to the requirement). Taking out the obtained microparticles, washing with 1-6% calcium chloride solution, placing in 1-6% calcium chloride solution, and storing at low temperature (4 deg.C) for use.

(4) Temperature response solution preparation: preparing NIPAAm (monomer) solution with mass concentration of 1-4% (when preparing the solution, fully stirring and mixing until completely dissolving), adding MBA according to 0.1-0.6 per mill of mass concentration, adding APS according to 0.1-0.6 per mill of mass concentration, adding TMEDA according to 0.5-3 per mill of volume percentage, fully stirring and mixing the obtained mixed solution at normal temperature until completely dissolving to prepare temperature response solution, and storing at normal temperature and shade for later use.

(5) And (3) placing the prepared calcium alginate particles in a temperature response solution, carrying out crosslinking reaction for 1-4h, and combining a temperature response high polymer material to the calcium alginate microspheres to obtain the temperature response intelligent microspheres for later use.

(6) preparation of pH response solution: preparing 1-5% AA solution (fully stirring to be completely mixed when preparing the solution), adding MBA into the solution according to 0.1-0.6 per mill of mass concentration, respectively adding APS and SBS according to 0.1-0.6 per mill of mass concentration, fully stirring and mixing the obtained mixed solution at normal temperature until completely dissolving to prepare pH response solution, and storing at normal temperature in shade for later use.

(7) And (3) washing the temperature response microspheres taken out of the temperature response system with deionized water, putting the temperature response microspheres into the pH response solution to react for 10-40min to obtain intelligent double-response microspheres, taking out the intelligent double-response microspheres, and storing the intelligent double-response microspheres in 1-6% calcium chloride solution for later use.

The following are two specific examples.

Example 1

(1) Preparing calcium alginate solution with mass concentration of 3% and calcium chloride solution with mass concentration of 5%. Titrating to obtain the calcium alginate inner core.

(2) Preparing a temperature response solution, putting the calcium alginate inner core into the solution, and reacting for two hours to obtain the temperature response microsphere.

(3) Preparing a pH response solution, putting the temperature response microspheres into the solution, and reacting for twenty minutes to obtain the temperature and pH response particles.

As shown in fig. 1, fig. 2, fig. 3 and fig. 4, fig. 1 shows that the surface and the internal structure of the prepared particles with dual temperature and pH responses are different, and a thin structural layer is formed on the surface of the particles, so that the intelligent dual response function can be realized; FIG. 2 shows that the presence of pockets, both on the surface and within the internal structure, provides sufficient space for microbial growth and mass exchange; FIG. 3 shows that the surface of the intelligent dual-response particle is discontinuous and non-uniform, and the material composition is non-uniform; fig. 4 shows that the microstructure of the surface of the intelligent dual-response particles is a three-dimensional network structure, and can provide an effective substance diffusion channel for metabolic substrates and products metabolized by microorganisms. Along with the change of temperature and pH, the size of the three-dimensional network structure pores can also be changed, thereby achieving the purpose of controlling the diffusion speed.

FIG. 5 is an infrared spectrum of blank calcium alginate microparticles, pH responsive microparticles, temperature responsive microparticles, dual responsive microparticles. Four kinds of microcapsules with the wavelength of 1700cm^-1On the left and right, a peak of absorption of carboxyl groups appears due to the fact that alginic acid itself has carboxyl groups. The temperature response calcium alginate microcapsule and the intelligent double response calcium alginate microcapsule have the wavelength of 3050cm^-1On the left and right sides, absorption peaks of amino groups are shown. The molecular structure of the temperature response microcapsule and the double response microcapsule contains amide group because of NIPAM in the molecule. The infrared spectrogram of the temperature and pH intelligent double-response calcium alginate particles is identical to the sum of the infrared spectrograms of the pH response particles and the temperature response particles. The double-response microsphere can be analyzed through Fourier transform infrared spectroscopy, and no more complex chemical bonds or copolymerization are generated in the internal molecular structure. Illustrating that the dual response is formed by both the pH response and the temperature response.

The appearance research of temperature response is carried out on the intelligent double-response macromolecule embedded particles, the color change of the particles in deionized water at 25 ℃ and 40 ℃ is respectively observed, the color change is a reversible process, and the color alternation can be controlled by changing the temperature.

The pH response appearance research is carried out on the intelligent dual-response macromolecule embedded particles, the color change of the particles in acidic and alkaline buffer solutions is respectively observed, the color change is a reversible process, and the color alternation can be controlled by changing the pH value.

Example 2

Example 2 preparation of embedded particles and control of conditions in the same manner as in example 1, the intelligent dual-response polymer embedded particles were subjected to appearance observation analysis of temperature response and pH response.

The microparticles were placed in purified water and heated, gradually increasing the temperature from 0 ℃ to 45 ℃ and the gradual transition from colorless to opalescent was observed. When the temperature is reduced from 45 ℃ to 0 ℃, the color is gradually changed from milky white to colorless and transparent. The color change is a reversible process.

In the solution at 25 ℃, the color of the particles is observed to gradually become lighter and transparent along with the increase of the acidity of the solution, and the color of the particles is gradually deepened into milky white along with the increase of the alkalinity of the solution. The process of response of the particle color change to pH is also a reversible process. The transparency of the particles is gradually reduced along with the reduction of the acidity of the solution, the transparency of the particles is gradually enhanced along with the reduction of the alkalinity of the solution, and the milky white color is gradually reduced.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.

Claims

1. A preparation method of intelligent polymer embedded particles is characterized by comprising the following steps:

(1) preparing a sodium alginate solution;

(2) preparing a calcium chloride solution;

(4) preparing a temperature response solution; the temperature response solution comprises the following components: NIPPAm with mass concentration of 1-4%, MBA with mass concentration of 0.1-0.6 ‰, APS with mass concentration of 0.1-0.6 ‰, and TMEDA with volume concentration of 0.5-3 ‰;

(5) putting the calcium alginate microspheres prepared in the step (3) into the temperature response solution prepared in the step (4) to carry out a crosslinking reaction, controlling the reaction time within 1-4h, and fully reacting to prepare the temperature response microspheres;

(6) preparing a pH response solution; the pH response solution comprises the following components: AA with the mass concentration of 1-5 percent, MBA with the mass concentration of 0.1-0.6 per mill, APS with the mass concentration of 0.1-0.6 per mill and SBS with the mass concentration of 0.1-0.6 per mill;

2. The method for preparing the intelligent polymer embedded particle as claimed in claim 1, wherein the mass concentration of the sodium alginate solution is 2-5%, the preparation temperature is 30-60 ℃, and the dissolution is sufficient.

3. The method for preparing intelligent polymer-embedded particles according to claim 1, wherein the mass concentration of the calcium chloride solution is 1-6%.

4. The method for preparing intelligent polymer-embedded particles according to claim 1, wherein in the step (3), the dripping height is 4-10cm, and the obtained calcium alginate microspheres are stored at low temperature for later use.

5. The method for preparing intelligent polymer-embedded particles according to claim 1, wherein in the step (7), the temperature-responsive microspheres are put into the pH-responsive solution to react for 10-40min, so as to obtain the dual-response intelligent polymer-embedded microspheres, and then the dual-response intelligent polymer-embedded microspheres are stored in 1-6% calcium chloride solution.