CN113457640A

CN113457640A - Method and device for preparing modified sponge with high amino content and algae removal application

Info

Publication number: CN113457640A
Application number: CN202110550297.9A
Authority: CN
Inventors: 叶林顺; 刘洁生; 杨维东; 欧浩楠; 黄隽萍; 梁泽雄; 王雅妮
Original assignee: Jinan University
Current assignee: Jinan University
Priority date: 2021-05-20
Filing date: 2021-05-20
Publication date: 2021-10-01
Anticipated expiration: 2041-05-20
Also published as: CN113457640B

Abstract

The invention belongs to the technical field of polymer adsorption materials, and particularly discloses a method and a device for preparing modified sponge with high amino content and application of the modified sponge in algae removal. According to the invention, a uniform reaction liquid thin layer is formed on the surface of the sponge, and crosslinking of polyethyleneimine and epoxy crosslinking agent in the thin layer is realized under mild conditions, so that a stable and uniform polyethyleneimine-epoxy crosslinking substance is formed on the surface of the sponge. The modified sponge has high amino content, environment friendliness and low sponge modification cost, and has good prospects in the application fields due to the special structure of the sponge. Fast algae removing speed, good algae removing effect, easy recovery and easy regeneration.

Description

Method and device for preparing modified sponge with high amino content and algae removal application

Technical Field

The invention belongs to the technical field of polymer adsorption materials, and particularly relates to a method and a device for preparing modified sponge with high amino content and application of the modified sponge in algae removal.

Background

Polymeric artificial sponges are a class of three-dimensional elastic materials with high porosity, low density and large specific surface area. Compared with the traditional form adsorbent, the artificial sponge has outstanding advantages in adsorption and liquid absorption.

Sponges are made in two routes for adsorption and liquid absorption purposes: firstly, the sponge is modified by taking the existing sponge as a carrier; secondly, a new sponge body is directly manufactured. The direct freeze-drying method and the method using crushed ice crushed to a certain size as a template both require freeze-drying and are extremely expensive. The two methods and the preparation of the porous material by taking the table salt crushed to a certain size as a template both need non-polar or low-polar organic solvents, and are not environment-friendly preparation processes. Although it is worth searching to directly produce a new sponge, the former sponge has far less advantages in terms of production cost, process and unique properties compared with the existing sponge, such as polyurethane PU sponge, melamine sponge, polystyrene sponge and other mature excellent sponges. There is a patent on the direct preparation of sponges from polyethyleneimine and epoxy cross-linking agents. The cross-linked sponge is prepared by cross-linking at a low temperature of-10 to-20 ℃, and only the cross-linking reaction needs 1 to 3 days. Even if sponges can be made, they are expensive to make and have no practical value unless used in very specific applications. The PU sponge in the existing sponge body is the most outstanding, so the PU sponge is a method with great application prospect for modifying the PU sponge.

The amino group is an important adsorption group, and the preparation of solid or sponge with high amino group content and the introduction of high-density amino group on the solid surface are always important research points. From the technical analysis of the introduced amine groups, the macromolecular amine with the highest amine group content is polyethyleneimine, and the monomer of the macromolecular amine is ethyleneimine. The direct polymerization introduction of the macromolecule on the surface of a solid phase has insurmountable inherent defects, such as that the polymerization of the ethyleneimine mainly occurs in a gas phase body, the polymerization proportion on the solid phase is low, and the process is difficult to realize. The method of introducing amido by multiple times of grafting has high cost and the effect is rapidly reduced along with the grafting times. Therefore, the formation of a crosslinked product of polyethyleneimine and a crosslinking agent on the solid surface is a technical choice for introducing a high amine group content. At present, in the polymerization or crosslinking grafting reaction for modifying the surface of a solid, the same reaction inevitably occurs in the liquid phase as the liquid phase main body coexists with the solid phase. Low raw material recovery rate, difficult post-treatment of modified solid and residual liquid treatment and environmental pollution. The ring-opening crosslinking reaction conditions of the polyethyleneimine and some crosslinking agents containing epoxy are mild, the environment is friendly, and the content of the amino group of the crosslinking agent is high. The layer of the cross-linked material must have good stability. Although direct sponges can be prepared by reacting polyethyleneimine with an epoxy-containing cross-linking agent, this approach has far from being advantageous in terms of manufacturing cost, processing, and properties unique to sponges.

Algae removal from water is still a long-felt need worldwide. The existing algae removal technology cannot meet the requirements of continuous and stable rapid algae removal, low cost, strong algae removal capacity, use of small water bodies and large water bodies and less secondary pollution.

The method can efficiently and quickly take out the algae cells from the water and separate the algae cells, and the off-line harmless treatment of the algae cells is an effective way for reducing secondary pollution in algae removal, and particularly has special significance for preventing microcystic aeruginosa from releasing microcystic toxins. The adsorption method is used for removing algae, and the adsorbent is required to be easily recycled and regenerated. At present, no algae removal adsorbent exists.

Disclosure of Invention

In order to overcome the disadvantages and shortcomings of the prior art, the invention provides a method for preparing a modified sponge with high amine group content.

The invention also aims to provide the modified sponge with high amino group content prepared by the method,

the invention further aims to provide application of the modified sponge with high amino group content in the field of algae removal.

The invention also aims to provide a method for removing algae by using the modified sponge with high amino group content

Still another object of the present invention is to provide an apparatus for preparing a modified sponge having a high amine group content.

The purpose of the invention is realized by the following scheme:

a method for preparing modified sponge with high amino group content specifically comprises the following preparation steps:

(1) putting the pre-cooled sponge into a wetting and extruding device from an inlet, mixing the pre-cooled polyethyleneimine solution with a 1, 4-butanediol diglycidyl ether ethanol solution to obtain a mixed solution, and adding the mixed solution into the wetting and extruding device from a feeding port;

(2) pushing a piston in the wetting and extruding device from bottom to top to extrude the sponge and the mixed solution, so that the surface of the sponge is completely immersed in the mixed solution; after the extrusion state is kept, the pressure is released, the natural state of the sponge is recovered, and reaction liquid films which are uniformly distributed are formed on the surface of the sponge;

(3) standing the sponge with the reaction liquid film uniformly distributed on the surface under a closed condition for a crosslinking reaction; and after the reaction is finished, washing until the pH value is unchanged, and drying to obtain the modified sponge with high amino group content.

The sponge in the step (1) is a sponge with a surface rich in hydrogen bonds, and is preferably PU sponge.

The concentration of the polyethyleneimine solution in the step (1) is 0.05-0.5 g/mL, preferably 0.1-0.4 g/mL, and more preferably 0.1 g/mL; the content of imine chain links in the polyethyleneimine solution is 2.33-9.32 g/mL, and preferably 2.33 mmol/mL; the molecular weight of the polyethyleneimine is 1800-70000, and is preferably 20000; the solvent of the polyethyleneimine solution is a mixed solvent of water and ethanol, and the volume ratio of the ethanol to the water is 0.5-1, preferably 1.

The concentration of the 1, 4-butanediol diglycidyl ether ethanol solution in the step (1) is 0.15-0.25 g/mL, and preferably 0.157 g/mL; the epoxy concentration of the 1, 4-butanediol diglycidyl ether ethanol solution is 1.0-1.5 mmol/mL, preferably 1.16mmol/mL calculated by the epoxy number of 0.74.

The molar ratio of the number of moles of imine chain links in the polyethyleneimine to the number of moles of epoxy groups in the 1, 4-butanediol diglycidyl ether in the mixed solution in the step (1) is 8-16: 1, and preferably 10: 1.

The pre-cooling in step (1) is preferably carried out by means of an ice-salt bath.

The density of the PU sponge in the step (1) is 20-80 mg/mL, preferably 22-60 mg/mL, more preferably 22mg/L and 60 mg/L. PU sponges with densities of 22mg/L and 60mg/L were respectively fully-perforated and semi-perforated correspondingly. The porosity is greater than 99%. And cooling the PU sponge, and then putting the cooled PU sponge into the mixed solution for soaking, extruding and uniformly wetting the surface.

The proportion of ethanol and water in the mixed solvent in step (1) is selected depending on the requirement that the crosslinking agent is completely dissolved even at low temperature.

The volume ratio of the mixed solution in the step (2) to the PU sponge is 0.144-0.313: 1;

in the extrusion state in the step (2), the sponge extrusion rate is 65-87.5%. Preferably 65% and 87.5%;

and (3) keeping the extrusion state for 1-3 min. And (4) decompressing to enable the sponge to reach a normal shape, and repeating the steps until the mixed solution forms a uniform liquid film layer on the surface of the sponge.

And (3) the crosslinking temperature is 35-50 ℃, and the crosslinking time is 90-120 min. Preferably, the temperature is 40 ℃. The cross-linking time is 90min and 120min, and the time is determined by the heat transfer affecting property and structural parameters of the reaction vessel and the sponge and the thickness of the liquid film. More preferably, the sponge is turned over for 180 degrees every 3-6 min before 25-35 min in the cross-linking process. Therefore, before the polyethyleneimine and the cross-linking agent in the liquid film are not fully cross-linked, the phenomenon that reactants are unevenly distributed due to downward flow of the liquid film gravity is reduced.

And (3) drying at the temperature of 45-50 ℃ under normal pressure or reduced pressure to constant weight.

The process parameters in the above modification step are further explained:

the molecular weight of the polyethyleneimine is 20000. Modification with two polyethyleneimines of molecular weight 70000, 1800 was also performed, and both of these polyethyleneimines of molecular weight were not suitable in comprehensive analysis of the swelling property of the crosslinked product, the molecular weight of the crosslinked product, and the fluidity of the reactant molecules in the liquid film layer. The crosslinking reaction is carried out in the liquid film thin layer under a mild condition, the requirement on a crosslinking agent is higher, and the original basic form of the sponge is still required to be maintained in the modified sponge. Experiments compare the modification effects of 1, 4-butanediol diglycidyl ether and polyethylene glycol diglycidyl ether, and the former is better.

The selection of the weight concentration of polyethyleneimine or the concentration of imine chain links, the weight concentration of 1, 4-butanediol diglycidyl ether ethanol solution and the epoxy concentration needs to ensure that no crosslinking reaction occurs in wetting, so that the reaction solution is uniformly wetted at low temperature. These several concentration options are also related to the amount of cross-linking formed in the thin layer of liquid film per unit area of sponge surface and also to the fluidity of the thin layer of reaction liquid film. The fluidity will affect the uniformity of the cross-links in the liquid film. In addition, the effects on the swellability of the crosslinked product, pore size and washing effect are also considered.

The ratio of the number of imine chain links to the number of epoxy groups is 10:1, which is a reasonable parameter derived from the degree of crosslinking and the amine group content of the crosslinker. Obviously less than 10:1, is not beneficial to ensuring the higher content of amino groups in the cross-linked substance, obviously more than 10:1, is not beneficial to forming the cross-linked substance with high molecular weight and reducing the stability of the cross-linked substance on the surface of the sponge.

The sponge extrusion rate operation value is related to the density of the sponge, the ratio of the volume (mL) of the reaction mixed liquid to the volume (mL) of the sponge, the opening rate of the sponge, the size of the sponge in operation, the swelling performance of the sponge by the solvent and the reactants, and the pore connectivity.

The crosslinking time is related to the molecular weight of the crosslinking substance, the stability of the crosslinking substance attached to the surface of the sponge, the shape maintenance of the sponge, the preheating time required by different sponge sizes, the geometric size of the sponge, the heat transfer effect of the reactor and the like.

The washing compression shrinkage is different from the wetting operation, and is related to the swelling property of the wet crosslinking matter, the opening rate of the sponge, the pore connectivity, the density of the sponge and the like.

A modified sponge with high amino group content is prepared by the method.

The modified sponge with high amino group content is applied to algae removal; the phylum algae is preferably blue algae, green algae and diatoms.

A method for removing algae through the modified sponge with high amino group content comprises the following steps: and (3) placing the modified sponge with high amino group content in the water body polluted by the algae to adsorb the algae.

Preferably, the modified sponge after the algae adsorption is recovered, regenerated and subjected to amine protonation for recycling.

A device for realizing the preparation method of the modified sponge with high amino group content comprises the following steps:

a wetting and extruding device and an auxiliary device;

the wetting and extruding device comprises a device wall, a piston in tight contact with the device wall, a pressurizing device, a feed inlet and a liquid outlet.

Preferably, the auxiliary device comprises a buffer bottle, a safety bottle and a tail gas washing and absorbing device.

The device can be used for forming other uniform reaction liquid films on the surface of the sponge or for manufacturing modified sponge by a dip coating method and washing sponge. In actual operation, the piston extrudes the sponge from bottom to top until the sponge is completely immersed in the reaction liquid, so that the reaction liquid is uniformly distributed on the surface of the sponge.

The invention has the beneficial effects that:

according to the invention, a uniform reaction liquid thin layer is formed on the surface of the PU sponge, and crosslinking of polyethyleneimine and an epoxy crosslinking agent in the thin layer is realized under mild conditions, so that a stable and uniform polyethyleneimine-epoxy crosslinking substance is formed on the surface of the sponge. The modified sponge has high amino content, environment friendliness and low sponge modification cost. Due to the special structure of the sponge, the modified sponge has good prospect in the application field. Fast algae removing speed, good algae removing effect, easy recovery and easy regeneration.

Drawings

FIG. 1 is a diagram of an apparatus used in the present invention.

FIG. 2 shows the change in the N-H and C-H infrared absorption intensities before and after sponge modification.

FIG. 3 is a comparison of the infrared characteristic absorption peaks of O-H, N-H in the sponge modification and in the starting material.

FIG. 4 shows the change in the infrared absorption peak of epoxy before and after the reaction of the raw material B.

FIG. 5 is a plot of pore size changes for an intact sponge and a modified sponge, wherein (a) is the intact sponge having a density of 22mg/mL, (b) is the modified sponge prepared in example 2, (c) is the intact sponge having a density of 60mg/mL, and (d) is the modified sponge prepared in example 3.

FIG. 6 shows the sponge before and after modification and the crosslinked material.

FIG. 7 is a graph showing the ratio (V) of the volume of water to the volume of sponge_w/V_s) And an intuitive map of the algae removal effect; from left to right are control group without sponge, V_w/V_s＝18.75、V_w/V_s＝9.38、V_w/V_s＝6.25、V_w/V_s＝4.69、V_w/V_s＝3.13。

FIG. 8 is a visual chart of adsorption time and algae removal effect; from left to right, respectively 0min, 1min, 5min, 10min, 20min, 30min, 60min, and 90 min.

FIG. 9 is a comparison of the algae removal effect of sponges of different densities; wherein (a) is a water sample image of the sponge in the example 1 after the algae removal at different time, (b) is a water sample image of the sponge in the example 3 after the algae removal at different time, (c) is a real image of the sponge in the example 1 after the algae removal, and (d) is a real image of the sponge in the example 3 after the algae removal.

FIG. 10 is a comparison of the color of the algae solution eluted by the regeneration solution and the color of the algae solution eluted by the modified sponge obtained in example 1.

FIG. 11 shows the algae removal effect of the raw solution and the modified sponge obtained in example 1 after 1-5 regeneration cycles from left to right.

FIG. 12 shows the appearance of the modified sponge obtained in example 1, after regeneration 1 to 5 times, as it is, from left to right.

FIG. 13 is a comparison of the algae removal effect before and after the amine group protonation treatment of two density modified sponges; wherein (a) is the modified sponge prepared in example 1; (b) the modified sponge prepared in example 3.

FIG. 14 is a front and back comparison of modified sponges of different sizes for removing copper and green microcystis; wherein (a) and (c) are the modified sponge prepared in example 2, the left is before algae removal, and the right is after algae removal; (b) and (d) is the modified sponge prepared in example 1.

Detailed Description

The present invention will be described in further detail with reference to examples and drawings, but the embodiments of the present invention are not limited thereto. The reagents used in the examples are commercially available without specific reference.

In the examples, the sponge weight W₀The weight gain delta W, the weight gain beta and the reaction yield zeta of the modified sponge are calculated by the following formula:

sponge extrusion rate η:

in the formula: v₀-volume of sponge before extrusion; v_s-volume of sponge after extrusion.

Example 1

The preparation method of the aminated low-density modified sponge specifically comprises the following preparation steps:

(1) feeding in a moistening and extruding device

The polyethyleneimine (ethanol: water ═ 1) solution with molecular weight of 20000 is used as the reaction solution of the raw material A, the weight concentration is 0.1g/mL, and the concentration of imine chain is 2.33 mmol/mL. The 1, 4-butanediol diglycidyl ether ethanol solution is used as a raw material B reaction solution, the weight concentration is 0.157g/mL, and the epoxy concentration is 1.16mmol/mL according to the epoxy number of 0.74. And (3) taking the reaction liquid A and the reaction liquid B with corresponding volumes according to the ratio of the number of imine chain links to the number of epoxy resin being 10:1, mixing and stirring uniformly under the cooling of an ice salt bath. A pre-cooled PU sponge of size 2X 2cm and density 22mg/mL was placed in the wet-pressing apparatus from the sponge inlet. The reaction mixture was fed from the feed port to the wetting apparatus as shown in FIG. 1. The ratio of volume of the reaction mixture (mL)/volume of the sponge (mL) was 0.144;

(2) wetting treatment for forming liquid film on surface of sponge

The PU sponge and the reaction mixture were pressed from bottom to top in the apparatus shown in FIG. 1, with a sponge pressing rate of 87.5%, so that the surface of the sponge was completely immersed in the reaction mixture. When the piston is at the extrusion position, the piston stays for 1min, then the pressure is relieved, and the sponge returns to the normal shape. When the pressure is released, the point C is closed, and the point A is communicated with the point B. This was repeated three times to form a uniform liquid film layer on the surface of the sponge.

(3) Microscopic characterization of cross-linking reaction in sponge surface liquid film layer and cross-linking reaction

Placing the sponge uniformly wetting the reaction mixture into a sealed reactor preheated at 40 deg.C and having good heat transfer performance, and crosslinking at 40 deg.C for 90 min. Turning the sealed reactor 180 degrees up and down once every 5min for the first 30min, wherein the cross-linking chemical reaction formula is shown as formula I.

(4) Washing of modified sponges

And transferring the product into an ice salt cooling bath for cooling after the reaction is finished, transferring the cooled sponge into a washing device, adding washing water according to 2 times of the volume of the sponge, washing for 15min in a shaking table (rotary type, shaking speed of 140r/min), taking out the sponge after the washing time is up, extruding the modified sponge in an extrusion device, wherein the sponge extrusion rate is 25%, and then adding the washing water for washing. And washing and extruding for 3-4 times until the pH value of the washing liquid is unchanged and the pH value of the effluent is slightly larger than 7.

(5) Drying modified sponge

After washing, sponge is extruded, and drying is carried out at the temperature of 45-50 ℃ under normal pressure or reduced pressure (the drying time can be influenced by the vacuum degree) until the weight is constant.

Example 2

The difference between the embodiment and embodiment 1 is that the size of the sponge is 10 multiplied by 2cm, the density is 22mg/mL, the sponge extrusion rate is 87.5%, and the crosslinking time is 120 min; the wash extrusion rate was 25%.

Example 3

The difference between the embodiment and the embodiment 1 is that the size of the sponge is 2 multiplied by 2cm, the density is 60mg/mL, the sponge extrusion rate is 65%, and the crosslinking time is 110 min; the wash extrusion rate was 50%.

Example 4

The difference between the embodiment and the embodiment 1 is that the size of the sponge is 10 multiplied by 2cm, the density is 60mg/mL, the sponge extrusion rate is 65%, and the crosslinking time is 120 min; the wash extrusion rate was 50%.

TABLE 1 Effect of modification of modified sponges obtained in examples 1 to 4

In examples 2 and 3, the IR spectra before and after modification of the starting material, the crosslinked material, and the sponge having two densities are shown in FIGS. 2 to 4. Wherein 22 sponge as such refers to the unmodified sponge of example 2, 22 modified sponge refers to the modified sponge prepared from example 2, 60 sponge as such refers to the unmodified sponge of example 3, and 60 modified sponge refers to the modified sponge prepared from example 3. From FIG. 2 and FIG. 3, it is seen that after the sponge is modified, the absorption peak of hydroxyl newly generated after the ring opening of epoxy is superposed with the absorption peak of N-H to form 3600cm^-1The absorption intensity is obviously increased to the wide peak of the N-H absorption wave number position, and the maximum absorption is at the N-H absorption wave number position. The intensity of the C-H characteristic absorption peak is obviously increased. It can be seen from figure 3 that the primary colour materials B are at 3499cm^-1The absorption peak of hydroxyl is shown, unlike modified sponge and the superposition peak of absorption of two groups of hydroxyl and N-H of a cross-linked substance, which indicates that a small amount of hydroxyl in butanediol in the raw material B is not completely etherified by glycidol. From FIG. 4, it can be seen that the characteristic absorption peak of epoxy in raw material B has disappeared in both the crosslinked material and the modified sponge, demonstrating that the epoxy groups in the crosslinking agent have reacted sufficiently with the amine groups in the polyethyleneimine. Examples 2 and 3 sponge modified front and rear holesThe gap structure is varied as shown in fig. 5. As can be seen from fig. 5, the sponge of both densities had smaller pores overall. FIG. 6 shows a schematic representation of the sponge as such, the modified sponge and the crosslinked material. The cross-linked product was also white in color and insoluble in water. No obvious change before and after sponge modification was seen in color.

The modified sponges of examples 1-4 were soaked in water, 0.5M aqueous sulfuric acid, and 0.5M aqueous sodium hydroxide for 48 hours at room temperature without weight loss. The crosslinked material attached to the sponge surface was a crosslinked product of polyethyleneimine and a crosslinking agent (number of imine links/number of epoxy groups: 10: 1). Although this crosslinked material contains a large number of hydrophilic amine groups and hydroxyl groups newly generated after ring opening, it is insoluble in water, indicating that the crosslinked material has a large molecular weight and that there are abundant hydrogen bonds between the amine groups and the hydroxyl groups in the crosslinked material molecule. Abundant hydrogen bonds also exist between amino groups and hydroxyl groups in the cross-linked substances and a structural unit-NHCOO-on the surface of the PU sponge. Therefore, the layer of the crosslinked material adhered to the surface of the PU sponge is excellent in stability. Therefore, the sponge modification is not limited to PU sponge, and the cross-linked substance modified layer with similar stability can be prepared by the invention as long as the surface of the sponge has abundant hydrogen bonds with the cross-linked substance. After the sponge is modified and extruded for 50 times, the included angle and the side length of the square are measured, and the shape is proved to be unchanged.

Example 5

And (3) completely squeezing the obtained modified sponge, then carrying out squeezing and wetting treatment on the modified sponge for 15min by using a dilute hydrochloric acid solution with the volume of 1/4 sponge and the concentration of 0.25M, completely protonating the amino group of the modified sponge, and putting the protonated modified sponge into the water body polluted by algae. The algae-containing water samples of the following (1) to (5) have algae phyla mainly including blue algae, green algae and diatoms. The modified sponges used in the following (1) to (5) were each a square of 2X 2cm in size. (6) The water sample is a copper-containing green microcystis water sample.

(1) Ratio (V) of water volume to sponge volume_w/V_s)

V_w/V_sThe modified sponges obtained in example 1 were protonated at room temperature in the absence of light, with settings of 3.13, 4.69, 6.25, 9.38, and 18.75, and with no sponge added as a control groupThe resultant was put into algae-contaminated water having a pH of about 7, and shaken at a low speed of 50r/min for 20min to conduct an adsorption test. FIG. 7 is V_w/V_sAnd an intuitive map of the algae removal effect.

(2) Different algae suction time

The time for absorbing algae was set to 0, 1min, 5min, 10min, 20min, 30, 60min, and 90min, and the modified sponge protonated in example 1 was put into algae-contaminated water with pH of about 7 at room temperature without light, and V_w/V_sThe adsorption test was carried out at 6.25 by shaking at a low speed of 50 r/min.

From fig. 8, it can be seen that when the algae suction time is 20min, although the best algae removal rate is not achieved, the algae removal effect is good, and the algae removal rate is 82% calculated according to the chroma removal rate. The rapid algae removal is beneficial to meeting the time requirement of emergency algae removal. The method has the advantages that the light-proof algae removal is avoided, the in-situ algae removal condition is realized, the algae removal effect is good, and the algae absorption speed of the modified sponge is proved to be in competitive advantage on the natural propagation speed of the algae.

(3) Comparison of algae-sucking effects of different sponge densities

The algae sucking time is set to be 0, 5min, 15min, 30, 60min and 90 min. The amine group protonated modified sponges of examples 1 and 3 were placed in an algae-contaminated water body at pH 7 at room temperature without being shaded from light, V_w/V_sThe adsorption test was carried out at 6.25 by shaking at a low speed of 50r/min for 20 min. The modified algae removal effect for the two examples at a density of 22mg/mL sponge and a density of 60mg/mL is shown in FIG. 9. After reaching algae absorption balance, the chroma removal rate is 86.2 percent and 85.3 percent. It is also seen from fig. 9 that the original sponges of both densities have a color reduction of about 8% after the same time contact with the algae-containing water sample, and the original sponges (unmodified sponges) have little color change. FIG. 9 is a comparative graph showing the appearance of a sponge having a density of 22mg/mL and a modified sponge having a density of 60mg/mL after adsorbing algae. It can be seen from the figure that the color of the sponge after absorbing algae with the low density of 22mg/mL in the initial stage of the absorption is darker than that of the sponge with the high density of 60mg/mL, but the colors are closer to each other in the later stage of the absorption. The reason is that the pore size of the low-density sponge is larger than that of the high-density sponge, so that the diffusion resistance is smaller and the algae absorption speed is higher. FromIn terms of cost, it is preferable to remove algae by using a low-density sponge.

(4) Regeneration of sponge and complete renewed protonation of sponge

And extruding and wetting the recovered sponge by using 0.25M sodium hydroxide solution for 15min, wherein the volume of the solution is 10% more than that of the protonized 0.25M hydrochloric acid solution, and extruding the sponge after alkali treatment after wetting to finish the regeneration operation. FIG. 10 is a comparison of the color of the algae solution eluted by the regeneration solution for sponge-adsorbed algae cells and the color of the original solution.

The regenerated modified sponge was completely protonated with 0.25M dilute hydrochloric acid solution and the alkali left in the liquid film layer after the regeneration treatment was just neutralized. FIG. 11 is a graph showing the effect of regenerating the modified sponge obtained in example 1 for 1 to 5 times. (pH 7 or so at room temperature, V_w/V_sShake at low speed at 50r/min for 20min 6.25, 50r/min, not protected from light). FIG. 12 is the appearance of the sponge after 1-5 regenerations.

(5) Comparison of the algae removal Effect of acid-treated and non-acid-treated modified sponges

The amine group is a group with strong protonation capability, the amine group protonation is one of the basic conditions for absorbing algae, and V is carried out at normal temperature without avoiding light_w/V_sThe modified sponges of examples 1 and 3, which were amine group-protonated and non-amine group-protonated, were put into algae-contaminated water at a pH of about 7 at 6.25, and subjected to an adsorption test by shaking at a low speed of 50r/min for 60 min. The algae removal effect is shown in the figure. As can be seen from FIG. 13, the effect of the protonation treatment was not significant, and the effect of removing algae was excellent. Therefore, the modified sponge of the invention can be used for removing algae without acid treatment. Squeezing the sponge after algae absorption, and then regenerating the sponge by using dilute alkali liquor. The sponge for eluting and adsorbing algae cells is squeezed, but a layer of dilute alkali liquor is still on the surface of the sponge. In order to reduce the cost of washing, dilute acid solution can be directly used for neutralizing the dilute alkali of the liquid film, and the protonation state of the sponge amine group can be recovered.

In summary, the algae removal operation and preferred conditions:

the first algae removal sponge may be without protonation. After the regeneration of the sponge, acid treatment is needed to recover the protonation state of the sponge amino group. Preferred conditions are: at normal temperature, pH 7 or so、V_w/V_sShaking at low speed of 50r/min for 20-60 min, without light shielding, 3-9.38. Aiming at the actual water sample containing algae, the algae removal rate can reach 82-86.2%.

(6) Modified sponge with different sizes for removing copper and green microcystis

The protonated amine group is a small group, and can effectively prevent the cells of the microcystis aeruginosa from being damaged when the microcystis is adsorbed and removed, thereby reducing the risk of releasing microcystin into a water body. The modified sponge has high algae removal speed and is favorable for preventing the risk of releasing microcystin into water.

The square pieces of modified sponge of example 1, size 2X 2cm and example 2, size 10X 2cm were directly put into a water sample containing microcystis aeruginosa without protonation treatment. The water sample containing copper-green microcystis has an algal cell density of 6.53 × 10⁶And measuring the absorbance of the algae/mL at a wavelength of 682nm to calculate the algae removal rate. The algae removal conditions are as follows: normal temperature, pH 7 or so, V_w/V_sShaking at low speed of 6.25 and 50r/min for 20min without light. The algae removal rate of the former obtained from the chromaticity removal rate reaches 83 percent, and the algae removal rate of the latter obtained from the chromaticity removal rate reaches 89 percent. See fig. 14.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

Claims

1. A method for preparing modified sponge with high amino group content is characterized by comprising the following preparation steps:

2. The method of claim 1, wherein:

the molar ratio of the number of moles of imine chain links in the polyethyleneimine in the mixed solution in the step (1) to the number of moles of epoxy groups in the 1, 4-butanediol diglycidyl ether is 8-16: 1.

3. The method of claim 1, wherein:

the sponge in the step (1) is PU sponge;

the concentration of the polyethyleneimine solution in the step (1) is 0.05-0.5 g/mL;

the concentration of the 1, 4-butanediol diglycidyl ether ethanol solution in the step (1) is 0.15-0.25 g/mL.

4. The method of claim 3, wherein: the density of the PU sponge in the step (1) is 22-80 mg/mL; the volume ratio of the mixed solution in the step (2) to the PU sponge is 0.144-0.313: 1.

5. The method of claim 1, wherein: in the extrusion state in the step (2), the sponge extrusion rate is 65-87.5%; and (3) keeping the extrusion state for 1-3 min.

6. The method of claim 1, wherein: and (3) the crosslinking temperature is 35-50 ℃, and the crosslinking time is 90-120 min.

7. A modified sponge with high amine content, which is prepared by the method of any one of claims 1 to 6.

8. Use of the modified sponge with high amine group content according to claim 7 for algae removal.

9. A method for removing algae from the high amine group content modified sponge of claim 7, comprising the steps of: and (3) placing the modified sponge with high amino group content into the water body polluted by algae to adsorb the algae.

10. An apparatus for implementing the method for preparing a modified sponge with high amine content according to any one of claims 1 to 6, which comprises a wet extrusion apparatus, wherein the wet extrusion apparatus comprises: the device wall, a piston closely contacted with the device wall, a pressurizing device, a feed inlet and a liquid outlet.