阅读说明：本技术 一种固定化酵母凝胶及其制备方法和应用 (Immobilized yeast gel and preparation method and application thereof ) 是由 傅丽君 于 2019-11-05 设计创作，主要内容包括：本发明公开了一种固定化酵母凝胶及其制备方法和应用,其包括丙烯酸酯凝胶和固定于该丙烯酸酯凝胶中的啤酒酵母。本发明以丙烯酸酯凝胶作为包埋剂固定化酵母,吸附重金属离子具有良好的吸附效果,在适当的条件下,对Pb～(2+)和Cd～(2+)的吸附率分别为97.15％和92.25％,且吸附后容易过滤除去,同时可对重金属进行回收,并减少对环境二次污染。(The invention discloses an immobilized yeast gel and a preparation method and application thereof, wherein the immobilized yeast gel comprises acrylate gel and beer yeast fixed in the acrylate gel. The invention takes the acrylate gel as the embedding agent to immobilize the yeast, has good adsorption effect on adsorbing heavy metal ions, and can adsorb Pb under proper conditions 2+ And Cd 2+ The adsorption rates of the metal oxide particles are respectively 97.15% and 92.25%, and the metal oxide particles are easy to filter and remove after adsorption, and meanwhile, the heavy metal can be recovered, and the secondary pollution to the environment is reduced.)

1. An immobilized yeast gel characterized by: the beer yeast is limited and enriched in folds of the acrylate gel, and carboxyl on the surface of the beer yeast and amino in the acrylate gel are subjected to amidation reaction and connected; the acrylate gel is prepared from raw materials including NaOH, deionized water, acrylamide, N-methylene bisacrylamide, acrylic acid and Irgacure1173, wherein the mass ratio of the N, N-methylene bisacrylamide to the acrylic acid to the acrylamide is 1: 15-17: 3-5, and the concentration of beer yeast in the acrylate gel is 4-6 g/L.

2. An immobilized yeast gel according to claim 1, wherein: the mass ratio of the N, N-methylene bisacrylamide to the acrylic acid to the acrylamide is 1: 16: 3.6.

3. An immobilized yeast gel according to claim 1, wherein: the concentration of the beer yeast in the acrylate gel is 5 g/L.

4. A process for the preparation of an immobilized yeast gel according to any one of claims 1 to 3, characterized in that: the method comprises the following steps:

(1) dissolving NaOH in deionized water at 0-4 ℃, and then adding acrylic acid to react for 0.4-0.6 h;

(2) adding acrylamide into the material obtained in the step (1), uniformly mixing, adding a proper amount of N, N-methylene bisacrylamide, ultrasonically dispersing and dissolving, then adding beer yeast, uniformly stirring, finally adding Irgacure1173, and fully and uniformly ultrasonically treating to obtain a suspension;

(3) and (3) placing the suspension in a mould, curing and drying to obtain the immobilized yeast gel.

5. The method of claim 4, wherein: the drying temperature is 65-75 ℃, and the drying time is 20-25 h.

6. Use of an immobilized yeast gel according to any one of claims 1 to 3 for the treatment of wastewater containing heavy metal ions.

7. The use of claim 6, wherein: the heavy metal ion comprises Pb²⁺And Cd²⁺。

8. The use of claim 7, wherein: specific conditions of the treatment include: the pH value of the waste water is 3.8-4.0, the initial concentration of heavy metal ions in the waste water is 95-105mg/L, the environmental temperature is 24-26 ℃, the treatment time is 1.8-2.2h, and the concentration of beer yeast in the waste water is 8-10 g/L.

9. The use of claim 8, wherein: specific conditions of the treatment include: the pH value of the wastewater is 4.0, the initial concentration of heavy metal ions in the wastewater is 100mg/L, the environmental temperature is 25 ℃, the treatment time is 2h, and the concentration of beer yeast in the wastewater is 9 g/L.

Technical Field

The invention belongs to the technical field of yeast immobilization, and particularly relates to immobilized yeast gel and a preparation method and application thereof.

Background

Modern industry is rapidly developing, and a large amount of wastewater containing heavy metals is generated, which causes serious pollution to water body structures. Heavy metals are harmful to human health through food chain enrichment due to their characteristics of strong toxicity, easy enrichment, difficult biological metabolism and the like. At present, the commonly used remediation methods for heavy metal pollution of water bodies comprise biological adsorption, electrochemistry, ion exchange, chemical precipitation, reverse osmosis, filtration and the like. The bioadsorption method uses organisms or their derivatives to adsorb metal ions in water, and has the advantages of good selectivity, wide material source, high adsorption rate, low cost, no secondary pollution, etc., and thus has attracted much attention. The microorganism species that have been developed for heavy metal adsorption in water bodies are bacteria, molds, yeasts, algae and the like. The yeast has the advantages of strong tolerance to external conditions, low price, easy obtainment and the like, so that the yeast has great potential when being used as the biological adsorbent.

In recent years, researches show that the dead yeast cells have the same adsorption performance as the living yeast cells, the selection of the adsorption materials is expanded from single living organisms to 'semi-living', 'semi-intact' organisms and even dead cells, and many scholars find that the dead cells or the 'semi-living', 'semi-intact' cells can adsorb metals with equal or higher efficiency, so that the problem that the application of the dead yeast cells is limited due to the toxic effect of high-concentration metal ions on the living organisms is solved. However, the free or suspended yeast has low mechanical strength and is difficult to separate and regenerate after adsorbing heavy metal ions. Meanwhile, the mechanical strength of the gel serving as the adsorbent is not strong due to the inherent structural nonuniformity and the insufficient effective energy dissipation mechanism, so that the development of the gel is limited to a great extent. If the gel is adopted to immobilize the yeast cells, the porosity, the stability and the hydrophilicity of the gel adsorbent can be increased, the adsorption efficiency of the adsorbent can be improved, the separation of the yeast cells and an adsorbate is facilitated, and secondary pollution is not easy to cause. The acrylate gel is a polymer, has high conductivity and good stability, and has better water absorption and swelling property than sodium alginate, so that the research adopts an acrylate gel embedding method to fix the saccharomycetes to develop the heavy metal Pb of the water body²⁺And Cd²⁺The pollution adsorption research shows that the prepared immobilized yeast adsorbent has the advantages of large treatment capacity, simple and convenient solid-liquid separation operation, convenient metal recovery and adsorbent regeneration and the like, and provides technical support for the development of novel biomass adsorbents.

Disclosure of Invention

The present invention aims to provide an immobilized yeast gel.

Another object of the present invention is to provide a method for producing the above-mentioned immobilized yeast gel.

It is still another object of the present invention to provide use of the above immobilized yeast gel.

The technical scheme of the invention is as follows:

an immobilized yeast gel comprises an acrylate gel and a beer yeast fixed in the acrylate gel, wherein the beer yeast is limited and enriched in folds of the acrylate gel, and carboxyl on the surface of the beer yeast and amino in the acrylate gel are subjected to amidation reaction and connected; the acrylate gel is prepared from raw materials including NaOH, deionized water, acrylamide, N-methylene bisacrylamide, acrylic acid and Irgacure1173, wherein the mass ratio of the N, N-methylene bisacrylamide to the acrylic acid to the acrylamide is 1: 15-17: 3-5, and the concentration of beer yeast in the acrylate gel is 4-6 g/L.

In a preferred embodiment of the invention, the mass ratio of N, N-methylenebisacrylamide, acrylic acid and acrylamide is 1: 16: 3.6.

In a preferred embodiment of the present invention, the concentration of the lager brewing yeast in the acrylate gel is 5 g/L.

The other technical scheme of the invention is as follows:

the preparation method of the immobilized yeast gel comprises the following steps:

(1) dissolving NaOH in deionized water at 0-4 ℃, and then adding acrylic acid to react for 0.4-0.6 h;

(2) adding acrylamide into the material obtained in the step (1), uniformly mixing, adding a proper amount of N, N-methylene bisacrylamide, ultrasonically dispersing and dissolving, then adding beer yeast, uniformly stirring, finally adding Irgacure1173, and fully and uniformly ultrasonically treating to obtain a suspension;

(3) and (3) placing the suspension in a mould, curing and drying to obtain the immobilized yeast gel.

In a preferred embodiment of the present invention, the temperature of the drying is 65-75 ℃ and the time is 20-25 h.

The invention adopts another technical scheme as follows:

the immobilized yeast gel is applied to the treatment of wastewater containing heavy metal ions.

In a preferred embodiment of the present invention, the heavy metal ion includes Pb²⁺And Cd²⁺。

Further preferably, the specific conditions of the treatment include: the pH value of the waste water is 3.8-4.0, the initial concentration of heavy metal ions in the waste water is 95-105mg/L, the environmental temperature is 24-26 ℃, the treatment time is 1.8-2.2h, and the concentration of beer yeast in the waste water is 8-10 g/L.

Still more preferably, the specific conditions of the treatment include: the pH value of the wastewater is 4.0, the initial concentration of heavy metal ions in the wastewater is 100mg/L, the environmental temperature is 25 ℃, the treatment time is 2h, and the concentration of beer yeast in the wastewater is 9 g/L.

The invention has the beneficial effects that:

1. the invention takes the acrylic ester gel as the embedding agent to immobilize the yeast to adsorb heavy metal ions, has good adsorption effect and can adsorb Pb under proper conditions²⁺And Cd²⁺The adsorption rates of the metal oxide particles are respectively 97.15% and 92.25%, and the metal oxide particles are easy to filter and remove after adsorption, and meanwhile, the heavy metal can be recovered, and the secondary pollution to the environment is reduced.

2. The acrylate gel has better water absorption and swelling property, has good adsorption effect on heavy metal ions, can provide an adsorption channel for beer yeast fixed in the acrylate gel, and has a promotion effect on the adsorption effect of the heavy metal ions.

Drawings

FIG. 1 is an infrared picture of yeast in example 1 of the present invention.

FIG. 2 is an infrared image of an acrylate immobilized yeast gel and an acrylate blank gel in example 1 of the present invention.

FIG. 3 is a SEM image (600X) of the surface of the acrylate blank gel in example 1 of the present invention.

FIG. 4 is an SEM photograph (1200X) of the surface of the gel of acrylate-immobilized yeast in example 1 of the present invention.

FIG. 5 shows the adsorption of heavy metal Pb by the blank acrylate gel in example 1 of the present invention²⁺Graph of the effect.

FIG. 6 shows that the blank acrylate gel absorbs heavy metal Cd in example 1 of the present invention²⁺Graph of the effect.

FIG. 7 is a graph showing the effect of pH on the adsorption rate of heavy metal ions in example 1 of the present invention.

FIG. 8 is a graph showing the influence of adsorption temperature on the adsorption rate of heavy metal ions in example 1 of the present invention.

FIG. 9 is a graph showing the effect of the initial concentration of heavy metal ions on the adsorption of heavy metal ions in example 1 of the present invention.

FIG. 10 is a graph showing the influence of adsorption time on the adsorption rate of heavy metal ions in example 1 of the present invention.

FIG. 11 is a graph showing the effect of yeast usage on the adsorption of heavy metal ions in example 1 of the present invention.

Detailed Description

The technical solution of the present invention will be further illustrated and described below with reference to the accompanying drawings by means of specific embodiments.

Example 1

1 materials and methods

1.1 Experimental materials and instruments

Experimental materials: CY beer active dry yeast (Angel Yeast Co., Ltd.); 2-hydroxy-2-methyl-1-phenyl-1-propanone (Irgacure1173), Acrylamide (AM), N-Methylenebisacrylamide (MBA), Acrylic Acid (AA) are all AR (Tianjin chemical Co.); sodium hydroxide (NaOH) AR (tianjin red rock chemical reagent plant); cadmium chloride, lead nitrate, nitric acid, absolute ethyl alcohol AR (national drug group chemical Co., Ltd.); the lead standard solution and the cadmium standard solution are GR (national analysis and test center for nonferrous metals and electronic materials).

The main apparatus is as follows: scanning electron microscope (Hitachi high and New technology Co.); flame atomic absorption spectrophotometer model AA-3510 (Shimadzu corporation, Japan); a hand-held UV curing machine (28095;, Baiside science and technology development, Inc., State); tencor 27 fourier type infrared spectrometer (BRUKER, germany); DGG-9053A electric heating constant temperature air-blast drying oven (Shanghai Sensin instruments laboratories, Inc.); a diaphragm vacuum pump (Tianjin Saiprui laboratory instruments Co., Ltd.); a constant temperature shaking incubator (Shanghai Mingzhi experiment Equipment Co., Ltd.); an ultrasonic vibration cleaner (ultrasonic instruments ltd, kunshan).

1.2 test methods

1.2.1 preparation of acrylate blank gel

Preparing a solidified gel sample, weighing 4.2500g of NaOH, dissolving in 13.948g of deionized water at 4 ℃, then adding an appropriate amount of AA, reacting for 0.5h, adding an appropriate amount of AM into the mixed solution, uniformly mixing, adding an appropriate amount of MBA, ultrasonically vibrating to dissolve, uniformly stirring, adding 0.1241g of Irgacure1173, and fully and ultrasonically treating to be uniform. Pouring the suspension into a glass mold, and curing for 5s by a curing machine to obtain the gel with a certain shape. Drying in an electrothermal constant temperature blast drying oven at 70 deg.C for 1d, and storing the slices in a drier.

1.2.2 preparation of acrylate-immobilized Yeast gel

Adding 5g/L of beer yeast into the acrylic ester gel suspension prepared in the step 1.2.1, stirring uniformly, adding 0.1241g of Irgacure1173, and fully performing ultrasonic treatment until the mixture is uniform. Pouring the suspension into a glass mold, and curing for 5s by a curing machine to obtain the gel with a certain shape. Drying in a drying oven at 70 deg.C for 24 hr, and storing in a drier.

1.2.3 acrylate blank gel and immobilized Yeast gel Infrared Spectroscopy scanning

Placing the prepared acrylate blank gel (see below), acrylate immobilized yeast gel (see below), and free yeast in an electrothermal constant temperature blast drying oven at 70 deg.C for 24h, grinding into powder with agate mortar, and drying at 400-4000cm^-1The absorption peaks of the spectrum are analyzed by scanning with Fourier infrared spectrum.

1.2.4 acrylate blank gel and immobilized Yeast gel Electron microscopy

And (3) placing the prepared acrylate blank gel, the acrylate immobilized yeast gel and the free yeast in an electrothermal constant-temperature air drying oven at 70 ℃ for drying for 1d, drying, grinding into powder, spraying gold on the sample powder, and performing scanning analysis on the sample through an electron microscope.

1.2.5 optimization of preparation process of acrylate immobilized yeast gel

Taking the quality (A) of N, N-methylene bisacrylamide, the quality (B) of acrylic acid and the quality (C) of acrylamide as influencing factors, selecting three levels for orthogonal test of each factor to obtain the optimal proportion of the embedding material with the optimal adsorption effect, wherein the orthogonal factor levels are shown in Table 1

TABLE 1 acrylic ester blank gel preparation Process factor horizon

1.2.6 adsorption of Pb by acrylate-immobilized Yeast gels under different conditions²⁺、Cd²⁺Test of

Respectively taking 50m of Pb with 1 concentration of 100mg/L²⁺And Cd²⁺Placing the solution in 5 conical flasks, adjusting pH to 2, 3, 4, 5 and 6 with 0.1mol/L NaOH and HCl, adding 1g of immobilized yeast gel with concentration of 5g/L, placing in a constant temperature shaking incubator at 180r/min and 25 deg.C for adsorption for 2h, filtering, and measuring heavy metal Pb with atomic absorption spectrophotometer²⁺And Cd²⁺Analyzing the influence of different pH values on the effect of adsorbing heavy metal ions by the acrylate immobilized yeast gel; controlling other conditions to be unchanged, setting the temperature of the constant-temperature oscillation incubator to be 10 ℃, 15 ℃, 20 ℃, 25 ℃ and 30 ℃ respectively, and analyzing the influence of the temperature on the effect of adsorbing heavy metal ions by the acrylate immobilized yeast gel; selecting the initial concentration of heavy metal ions as an influencing factor, preparing the concentrations of ions by using heavy metal salts to be 20mg/L, 40mg/L, 60mg/L, 80mg/L and 100mg/L, and analyzing the influence of different initial concentrations of the heavy metal ions on the effect of the acrylate immobilized yeast gel on adsorbing the heavy metal ions; controlling other factors to be unchanged, sampling at intervals, setting the time of the constant-temperature shaking incubator to be 1h, 1.5h, 2h, 2.5h and 3h, and analyzing the shaking time to fix the acrylate yeast gelThe effect of adsorbing heavy metal ions; and (3) controlling other conditions to be unchanged, selecting the concentration of the added yeast within the range of 3-12 g/L, and analyzing the influence of the concentration of the yeast on the effect of the acrylate immobilized yeast gel on adsorbing heavy metal ions.

1.3 data processing

Determination of heavy metal Pb in solution after adsorption by atomic absorption spectrophotometer²⁺And Cd²⁺Concentration of (b), Pb²⁺Equation A of the standard curve is 0.0258C₀+0.0027，(R²＝0.9976)，Cd²⁺Standard curve equation of (A) ═ 0.6110C₀+0.0002，(R²＝0.9983)。

Specific adsorption rate of gel^[12]The calculation formula of (a) is as follows:

A＝(Co-C)/Co

in the formula: a: unit gel adsorption rate%

C₀: initial concentration of heavy metal ions, mg/L

C: concentration of heavy metal ion after completion of adsorption, mg/L

2 results and analysis

2.1 characterization of Yeast, acrylate blank gel, acrylate immobilized Yeast gel

2.1.1 Infrared Spectroscopy

As can be seen from FIG. 1, there is a significant absorption over the entire wavenumber range, 3296.38cm^-1The strong broad peaks are associated O-H stretching vibration peaks and-NH stretching vibration peaks; 2962.79cm^-1And 2931.04cm^-1Is represented by CH₂And CH₃The asymmetric stretching vibration peak of (1); 1452.10cm^-1And 1400.72cm^-1Is represented by CH₂And CH₃Asymmetric bending vibration peak of (a); 1655.94cm^-1The position is an amide C ═ O stretching vibration peak; 1540.70cm^-1The peak of the bending vibration of the amide N-H and the peak of the stretching vibration of the amide C-N are shown; 1236.07cm^-1Is the stretching vibration peak of amide C-N, and possibly P ═ O stretching vibration; 1057.43cm^-1And the position is an expansion vibration peak of S ═ O.

As can be seen from FIG. 2, the blank gel of acrylate was 3000-3600cm^-1One wide suctionCollecting band with maximum absorption of 3400cm^-1Where, caused by H-O stretching vibration, is 1039cm^-1The characteristic absorption peak is polysaccharide skeleton vibration absorption band at 1338cm^-1The characteristic absorption peak is caused by cyclic C-H and is 1086cm^-1The absorption peak is caused by C-O stretching vibration in alcohol, and is 1615cm^-1The characteristic absorption peak nearby is mainly caused by H-O bending vibration and is 2941cm^--1The characteristic absorption peak is-CH in the acrylate₂- (macromolecular six-ring) asymmetric stretching vibration at 1421cm^-1The characteristic absorption peak is caused by-COO-symmetric stretching vibration.

The absorption peak of the acrylate immobilized yeast gel is basically unchanged from the infrared spectrum of the acrylate blank gel, and is 3400cm^-1Nearby broadband absorption peaks may also result from stretching vibrations of-OH in chitin and N-H in secondary amines, but at 954cm^-1An absorption peak is added and is a characteristic peak of ester carboxyl, which indicates that carboxyl on the surface of the yeast cell can be subjected to esterification reaction with alcohol, and the main components and the structure of the esterified yeast still keep complete.

2.1.2 scanning Electron microscopy analysis of acrylate blank gels and acrylate immobilized Yeast gels

The morphology of the acrylate blank gel and the acrylate immobilized yeast gel by scanning electron microscopy is shown in FIG. 3 and FIG. 4.

The acrylate gel is prepared by using NaOH, deionized water, acrylic acid, acrylamide, N-methylene bisacrylamide and Irgacure 1173. The mass ratio of N, N-methylene bisacrylamide, acrylic acid and acrylamide in the acrylate gel is 1: 16: 3.6, 5ml of 5g/L yeast is added in the preparation process of the acrylate to prepare the acrylate immobilized yeast gel, and the surface morphology observation graphs are compared with those shown in figures 3 and 4, so that the acrylate blank gel and the acrylate immobilized yeast gel have no difference in visual morphology and are both polymer gels. According to the surface morphology chart of the acrylate immobilized yeast gel, the gel surface after yeast immobilization presents more folds, and the folds are beneficial to yeast enrichment, so that the adsorption effect on heavy metal ions is improved. M. Fomina et alThe yeast is proved to be Zn by using Scanning Electron Microscope (SEM) and X-ray absorption spectroscopy (XAS)²⁺、Cu²⁺And Pb²⁺The oxygen-containing functional groups (such as phosphate group, carboxyl group, etc.) on the surface of yeast cells play an important role in the interaction of (1) and an ion coordination model is proposed.

2.2 optimization results of preparation Process of acrylate-immobilized Yeast gel

2.2.1 acrylate gel pair after optimization for Pb²⁺Adsorption rate of (2)

By means of L₉(3³) Orthogonal table develops the acrylate blank gel for Pb²⁺The adsorption test of (2) and the test results are shown in Table 2.

TABLE 2 acrylate blank gel L₉(3³) Adsorption effect of orthometric test on heavy metal lead

The magnitude of the range may reflect the magnitude of the effect on the test results when the factor level is changed. From the range values in table 2, the primary and secondary sequence of each factor is: a (N, N-methylene bisacrylamide) > B (acrylic acid) > C (acrylamide) shows that the mass of N, N-methylene bisacrylamide has a significant influence on the lead adsorption capacity of the acrylamide blank gel, and the mass fractions of acrylic acid and acrylamide have a small influence on the lead adsorption capacity of the acrylamide blank gel. Therefore, it can be judged that A is the best at the level 1, B is the best at the level 2, and C is the best at the level 2, namely the best condition is that N, N-methylene bisacrylamide is 0.5g, acrylic acid is 8g, and acrylamide is 1.8g, and the adsorption rate of the acrylic ester blank gel on lead reaches 73.2 percent under the condition. The effect of each factor is shown in graph 5.

FIG. 5 shows the adsorption of Pb on blank acrylate gel by three-factor level quality change²⁺Graph of effects of (a). As shown in the figure, the mass effect curve of N, N-methylene-bisacrylamide decreases with increasing mass, the best adsorption effect is achieved when the mass of acrylic acid is 8g, and the mass effect curve of acrylamide increases first and then decreases with increasing mass.

2.2.2 acrylate blank gel Pair Cd²⁺Adsorption rate of (2)

By means of L₉(3³) Orthogonal table develops the blank gel pair Cd of acrylate²⁺The adsorption test of (2) and the test results are shown in Table 3.

From the difference values in table 3, the primary and secondary sequence of each factor is: the mass fraction of the acrylic acid has larger influence on the adsorption performance of the blank acrylic ester gel for adsorbing heavy metal cadmium, and the mass of the N, N-methylene bisacrylamide and the acrylamide has smaller influence on the adsorption performance of the blank acrylic ester gel for adsorbing heavy metal cadmium. Through the values of K1, K2 and K3, the adsorption rate of the heavy metal cadmium reaches 65.3%, and the effect curve chart of each factor is shown in FIG. 6, wherein A is the best at the level 1, B is the best at the level 2, and C is the best at the level 2, namely the best condition is A1B2C 2.

TABLE 3 acrylate gel L₉(3³) Adsorption effect of orthogonal test on heavy metal cadmium

FIG. 6 shows adsorption of Cd on blank acrylate gel by three factors of mass change²⁺The effect is influenced to present an effect curve diagram. From this figure, it is understood that the increase in the mass of acrylic acid suppresses the adsorption of heavy metal ions by the acrylic acid ester blank gel, and that the adsorption effect is the best when the mass of N, N-methylenebisacrylamide is 0.5g, and the acrylamide mass effect curve fluctuates smoothly as a whole.

2.3 adsorption of Cd on acrylate immobilized Yeast gel under different conditions²⁺、Pb²⁺Influence of (2)

2.3.1 Effect of pH on adsorption

As can be seen from FIG. 7, when the pH is in the range of 2 to 5, the adsorption rate of heavy metal ions tends to increase as the pH increases. The pH value is increased, the adsorption effect of the acrylate immobilized yeast gel on heavy metal ions is promoted, and Pb is obtained when the pH value is 5²⁺The adsorption effect is optimal, and the adsorption rate is 80.6%. Cd [ Cd ]²⁺With Pb²⁺Slightly different, Cd²⁺The adsorption effect is best when the pH value is 6, and the adsorption rate is 76.5%.

Simulating a large amount of H when the pH value in the heavy metal polluted wastewater sample is lower₂O³⁺Compete with heavy metal ions for active adsorption sites on the cell surface, resulting in a decrease in adsorption rate, and functional groups such as-COOH and-OH also hinder Pb at low pH²⁺Adsorption of (3). With the increase of pH, the protonation on the cell surface dissociates the functional groups, and more negatively charged sites are exposed, so that the combination with heavy metal ions is facilitated; when the pH value is higher, the metal ions are easy to form insoluble precipitate particles such as oxides, hydroxides and the like and cover the cell surface, the yeast cannot be combined with the heavy metal ions, the adsorption of the heavy metal ions is not facilitated, and the adsorption can be even stopped

2.3.2 Effect of temperature on adsorption

As can be seen from fig. 8, the temperature also has an important influence on the adsorption efficiency in the process of adsorbing heavy metal ions by yeast. With increasing temperature, Pb²⁺With Cd²⁺The adsorption rate of (A) gradually increases, the increase range is large in the range of 20-25 ℃, and Pb is large in the temperature of 25 DEG C²⁺With Cd²⁺The adsorption effect of the adsorbent is optimal, and the adsorption rates are respectively 83.2% and 79.3%. Zeia glans et al consider that biosorption is an exothermic process, and a large increase in temperature is detrimental to biosorption. Meanwhile, the saturation adsorption rate is reduced due to the over-high temperature or the under-low temperature.

2.3.3 different Pb²⁺、Cd²⁺Influence of the initial concentration on the adsorption

As can be seen from FIG. 9, it follows Pb²⁺And Cd²⁺As the initial concentration increases, the adsorption rate tends to increase. The adsorption effect is best when the concentration is 100mg/L, and the adsorption rates are 84.6 percent and 83.9 percent respectively. When the amount of the adsorbent is a certain amount, the adsorption rate of the metal ions generally becomes gentle with the increase of the initial concentration, which indicates that when the metal ions reach a certain concentration, although a large amount of metal ions remain in the adsorption system, the yeast cells can be bondedThe metal ion sites are saturated, and the adsorption rate of the thalli to the metal ions is not obviously increased.

When the concentration of heavy metal ions is higher, active free radicals in cells are increased, the original balance of the active free radicals is broken, the free radicals react with unsaturated fatty acid on cell membranes to be overoxidized, the permeability and the structure of the cell membranes are changed, the normal metabolism of the cells is hindered, and the heavy metal ions also inhibit the activity of enzyme after entering the cells in large quantity, so that the activity of the enzyme for eliminating the action of the free radicals is reduced, the lipid peroxidation of the cell membranes is intensified, the structure of yeast is damaged, and the acrylate immobilized yeast gel is used for treating Pb²⁺With Cd²⁺The adsorption effect of (2) is decreased.

2.3.4 Effect of different times on adsorption

As can be seen from fig. 10, the adsorption rate of the acrylate-immobilized yeast gel to the heavy metal ions increased with the increase of the adsorption time, but the adsorption rate did not increase because the yeast could completely adsorb the heavy metal ions in a short time and reached saturation. After the adsorption rate reaches the maximum at 2h, the adsorption rate tends to be saturated, and Pb is²⁺And Cd²⁺The adsorption rates of (A) were 87.5% and 85.9%, respectively. At the time of initial adsorption, Pb²⁺And Cd²⁺The heavy metal ions are firstly adsorbed on the surface of the cell, and then gradually enter the interior of the cell by permeating the cell membrane at a very slow speed, and gradually reach the adsorption balance, but the heavy metal ions can also be desorbed along with the continuous extension of the treatment time.

2.3.5 influence of Yeast dosage on adsorption

As can be seen from FIG. 11, the increase in the concentration of yeast resulted in immobilization of heavy metal ions Pb by the yeast²⁺、Cd²⁺The adsorption rate of (2) was gradually increased, but the adsorption rate was not continuously increased when the adsorption sites were saturated, and the adsorption reached equilibrium at a concentration of 9.0g/L, with adsorption rates of 94.5% and 90.3%, respectively. Probably because the constituent structures of yeast cells are mostly amphiphatic groups, and the increase of the concentration of yeast increases the probability of interaction between adsorption sites, thereby occupying a part of the effective sitesSo that the optimum concentration for yeast adsorption was 9.0 g/L.

Example 2

From the results of example 1, it was confirmed that the specific preparation process of the acrylate-immobilized yeast gel used in this example included: weighing 4.2500g of NaOH, dissolving the NaOH in 13.948g of deionized water at 4 ℃, adding an appropriate amount of acrylic acid, reacting for 0.5h, adding an appropriate amount of acrylamide into the mixed solution, uniformly mixing, adding an appropriate amount of N, N-methylene bisacrylamide, ultrasonically vibrating to dissolve, adding 5g/LCY beer active dry yeast, uniformly stirring, adding 0.1241g of Irgacure1173, and fully and ultrasonically treating to be uniform; pouring the suspension into a glass mold, and curing for 5s by a curing machine to obtain gel with a certain shape; drying at 70 deg.C for 1d, and storing the slices in a drier. Wherein the mass ratio of the N, N-methylene bisacrylamide to the acrylic acid to the acrylamide is 1: 16: 3.6.

The preparation of an acrylate blank gel for comparison included: 4.2500g of NaOH is weighed and dissolved in 13.948g of deionized water at 4 ℃, then added into a proper amount of acrylic acid, after 0.5h of reaction, a proper amount of acrylamide is added into the mixed solution and mixed evenly, a proper amount of N, N-methylene bisacrylamide is added for dissolving by ultrasonic oscillation, 0.1241g of Irgacure1173 is added after even stirring, and the mixture is fully and ultrasonically treated to be even. Pouring the suspension into a glass mold, and curing for 5s by a curing machine to obtain the gel with a certain shape. Drying in an electrothermal constant temperature blast drying oven at 70 deg.C for 1d, and storing the slices in a drier. Wherein the mass ratio of the N, N-methylene bisacrylamide to the acrylic acid to the acrylamide is 1: 16: 3.6.

And (3) carrying out wastewater treatment comparison on the prepared acrylate immobilized yeast gel, the acrylate blank gel and the CY beer active dry yeast under the following process conditions: the pH of the wastewater was 4.0, and heavy metal ions (Pb)²⁺And Cd²⁺) The initial concentration in the wastewater is 100mg/L, the environmental temperature is 25 ℃, the treatment time is 2h, and the concentration of the beer yeast in the wastewater is 9 g/L; the comparative results are shown in table 4 below:

TABLE 4 three adsorbents for heavy metals Pb²⁺And Cd²⁺Comparison of adsorption Effect

And 5 adsorption-desorption tests of the acrylate immobilized yeast gel on Pb²⁺And Cd²⁺The adsorption rates of (A) are still higher than 70% and 60%, respectively.

The above description is only a preferred embodiment of the present invention, and therefore should not be taken as limiting the scope of the invention, which is defined by the appended claims.