CN109650602B

CN109650602B - Method for removing antimony ions in water body by using magnetic adsorption material

Info

Publication number: CN109650602B
Application number: CN201910108202.0A
Authority: CN
Inventors: 朱国成; 詹浩
Original assignee: Shiny Materials Science & Technology Inc
Current assignee: SHINY MATERIALS SCIENCE & TECHNOLOGY Inc.
Priority date: 2019-02-03
Filing date: 2019-02-03
Publication date: 2021-11-05
Anticipated expiration: 2039-02-03
Also published as: CN109650602A

Abstract

The invention relates to a method for removing antimony ions in a water body by using a magnetic adsorption material, which comprises the following steps: s1: pretreating a water body: adjusting the pH value of the water body to make the water body alkaline; and/or diluting the water body to reduce the concentration of pollutants in the water body; s2: adding composite material CMC into the water body, and stirring: the ratio of the adding amount of the composite material CMC to the volume of the water body is as follows: 0.2 g/L-1.2 g/L, the adding mass of the composite material CMC and the volume unit of the water body are required to be on an order of magnitude; then quickly stirring for 0.5-3 h, slowly stirring for 0.5-3 h, finally standing for more than 30min, and separating the adsorbent by an external magnetic field. The composite material CMC can be stably distributed in a water body, and can be well recycled by virtue of good magnetic efficiency. And the chitosan is green and nontoxic, has a good adsorption effect, and cannot cause secondary pollution to a water body when being used as a carrier.

Description

Method for removing antimony ions in water body by using magnetic adsorption material

Technical Field

The invention relates to the field of energy environmental protection, in particular to a method for removing antimony ions in a water body by using a magnetic adsorption material.

Background

With the rapid development of industry and agriculture, the problem of water pollution caused by heavy metals has become the focus of social attention. Antimony (Sb) is a toxic and potentially carcinogenic metal element, widely present in the living environment of humans, where the problem of contamination by antimony metal remains to be solved. Antimony contamination formation is widespread in sources such as: the exploitation and smelting of antimony easily causes serious soil pollution near the site, and brings health threat to residents in peripheral areas; antimony and its compounds are widely used in the production of various industrial products (such as ceramics, ammunition, glass, batteries, paints, pyrotechnic materials) with environmental pollution problems associated with the release of heavy metals during the production process; sb present in ammunition and flame retardants is harmful to the human body. Antimony and its compounds, like arsenic and its compounds, have significant health effects in humans, e.g., (1) through the water-soil-crop-human food chain, the transfer of antimony and its compounds into the human body destroys enzymatic activity in the human body, leads to metabolic disorders, damages to the nervous system and other organs; sb contamination in natural surface water has toxic and adverse effects on human blood, gastrointestinal tract and respiratory system; (2) human inhalation of antimony causes irritation of the skin and eyes. Antimony plaque is a rash that infects sweat and sebaceous glands, one of the most severe skin irritations; (3) oral administration of water-soluble antimony salts through drinking water or food can cause irritation of the gastrointestinal mucosa, causing various adverse health effects such as vomiting, abdominal pain, diarrhea and human cardiotoxicity. Sb has a chemical property similar to arsenic and a different morphological structure, but in the environment Sb (iii) and Sb (v) are the predominant oxidation states, and Sb (iii) is 10 times more toxic than Sb (v). The research on the method and the technology for treating the Sb (III) of the water body has practical engineering value.

The prior antimony removal method mainly comprises an electrochemical analysis method, an ion exchange method, an extraction method, a membrane separation method and an adsorption method. The electrochemical method mainly has the functions of coagulation, adsorption, flotation, oxidation, micro-electrolysis and the like, and the processes of coagulation, electro-adsorption, electro-flotation and electro-oxidation are frequently adopted in the sewage treatment process. The mechanism of ion exchange is similar to that of adsorption, both of which are capable of absorbing solutes from solution. Extraction refers to the process of transferring a substance from one solvent to another solvent under conditions of different solubility or partition coefficients, and by repeated transfer extractions, a large fraction of the material can be extracted. The membrane separation technology is a novel water treatment technology, but the energy consumption is high. Compared with the traditional technologies of coagulation, precipitation, ion exchange and membrane separation, the adsorption technology has the advantages of low cost, low sludge yield, simple operation, strong regeneration capacity and the like, and is a high-efficiency antimony purification technology. The adsorption effect depends mainly on two aspects: the chemical nature of the adsorbent and the substance being adsorbed. The method provides a novel method for removing antimony ions in water by using a magnetic adsorption material.

Disclosure of Invention

Aiming at the problems in the prior art, the invention aims to provide a method for removing antimony ions in a water body by using a composite material CMC, which can effectively and quickly remove Sb (III) in the water body by adopting an adsorption method, has high removal rate and does not have secondary pollution to the water body.

In order to achieve the purpose, the invention adopts the following technical scheme: a method for removing antimony ions in a water body by using a magnetic adsorption material comprises the following steps:

s1: pretreating a water body:

adjusting the pH value of the water body to make the water body alkaline;

and/or diluting the water body to reduce the concentration of antimony ions in the water body;

s2: adding composite material CMC into the water body, and stirring: the ratio of the adding amount of the composite material CMC to the volume of the water body is as follows: 0.2 g/L-1.2 g/L, the adding mass of the composite material CMC and the volume unit of the water body are required to be on an order of magnitude; then quickly stirring for 0.5-3 h, slowly stirring for 0.5-3 h, finally standing for more than 30min, and separating the adsorbent by an external magnetic field.

As an improvement, the pH value of the water body is adjusted to 11-12 in S1, so that the water body is strong in alkalinity.

As an improvement, the water body is diluted in S1, and the metal Sb in the water body is reduced, so that the concentration of the metal Sb in the water body is 5 mg/L-30 mg/L.

As an improvement, the water body is diluted in the step S1, so that the concentration of metal Sb in the water body is 5 mg/L.

As an improvement, the ratio of the rotating speed of the rapid stirring to the rotating speed of the slow stirring is 3.5: 1.

as an improvement, in the step S2, the mixture is stirred rapidly for 2 hours and then slowly for 2 hours.

Compared with the prior art, the invention has at least the following advantages:

the magnetic organic framework material can enhance the dispersibility of the magnetic organic framework material in the environment and improve the performance of the magnetic organic framework material for adsorbing heavy metals in a certain way. Therefore, the composite material CMC can be stably distributed in the water body, and can be well recycled by virtue of good magnetic efficiency. And the chitosan is green and nontoxic, has a good adsorption effect, and cannot cause secondary pollution to a water body when being used as a carrier. Meanwhile, the magnetic organic framework material has a unique mesoporous structure and excellent adsorption performance, the advantages of the two materials are better exerted by the addition of the chitosan, and the combination of the three materials is accompanied with the physical and chemical reaction of surface functional groups.

Drawings

FIG. 1 shows the effect of CS and MOFs ratios on Sb (III) removal rate.

FIG. 2 is Fe₃O₄Ratio of CS to Sb (III) removal rateThe influence of (c).

FIG. 3 is a graph showing the effect of reaction temperature on the Sb (III) removal rate.

FIG. 4 is a graph showing the effect of reaction time on the Sb (III) removal rate.

FIG. 5 is a graph showing the effect of the initiator on the removal rate of Sb (III).

Fig. 6 is a hysteresis loop for three materials.

FIG. 7 shows the effect of different pH values on the removal of Sb (III) by CMC.

FIG. 8 is a graph of the effect of different initial concentrations on CMC removal of Sb (III).

FIG. 9 is a graph showing the effect of stirring time on removal of Sb (III) by CMC.

Detailed Description

The process of the invention is described in further detail below.

A method for removing antimony ions in a water body by using composite material CMC comprises the following steps:

s1: pretreating a water body:

adjusting the pH value of the water body to make the water body alkaline;

Preferably, the pH value of the water body is adjusted to 11-12 in the S1, so that the water body is strong in alkalinity.

Firstly preparing 1g/L of antimony ion solution, then transferring the antimony ion solution into a 250ml beaker, diluting the solution to 10mg/L, and adjusting the pH of the antimony ion solution to 1, 5, 6, 7, 9 and 11 by using dilute hydrochloric acid and sodium hydroxide. Then dividing the mixture into 3 groups with the same conditions except different pH values, and adding the CMC with the optimal preparation conditions of 100mg, 200mg and 300mg into each group respectively. And finally, placing the mixture on a six-joint stirrer for carrying out an adsorption experiment, quickly stirring for half an hour (210r/min), slowly stirring for half an hour (60r/min), and after settling for half an hour, taking the supernatant of a water sample to measure the concentration of antimony ions.

The effect of pH on Sb (III) removal rate is shown in FIG. 7. It is clear from the figure that the effect of CMC on Sb (iii) removal steadily increases with increasing amounts of CMC added under the same pH conditions. When the CMC addition amount was 100mg, 200mg and 300mg, the removal rate tended to increase first and then decrease and increase again. When the antimony ion solution is acidic and neutral, the removal rate of the CMC to antimony ions is not more than 50%. The removal rate of Sb (III) was the lowest at pH 1. And when the adding amount is 300mg, the removal rate does not exceed 40 percent. This indicates that CMC has a poor effect on Sb (III) removal under strongly acidic conditions. This is probably because the positive charges on the surface of the composite material are repulsive to the positively charged metal ions under acidic conditions. At pH 7, the removal rate was slightly improved under strongly acidic conditions, but the effect of removing Sb (III) was not significant. When the pH value is 11, the CMC has the best effect of removing the antimony ions, and when the adding amount is 100mg, the removal rate reaches 52.03 percent; when the adding amount is 300mg, the removal rate reaches 87.79 percent. This indicates that CMC has a very good effect on Sb (III) removal under strongly alkaline conditions.

By analyzing the influence of CMC on the Sb (III) removing effect under different pH values, the Sb (III) removing effect is excellent under the strong alkaline condition; under acidic conditions, the effect of removing Sb (III) is weak. Under acidic conditions, carboxyl and hydroxyl functional groups on the surface of the MOFs are protonated, and protons are reacted with-COO^-and-OH^-The radicals compete for the positively charged metallic antimony ions, so the elimination efficiency of Sb (III) is low. In addition, under weakly acidic conditions, MOFs materials only partially decompose under boiling conditions, whereas at pH 7, MOFs materials already disintegrate at room temperature. When the pH value is under the strong alkali condition, Sb (III) exists in the form of anions, and carboxyl and hydroxyl functional groups on the surface of the MOFs material are represented as-COO^-and-O^-Both ionic forms exist, and it is clear that electrostatic adsorption is not the predominant mode here. The hydrogen bond effect and the pi-pi bond of the imidazole ring and the aromatic ring are one of the main reasons that the organic metal framework material has good adsorption effect on the hydroxyquinone under the alkaline condition. The composite material is similar to the adsorption mechanism under strong alkaline conditions, so that the composite material has a good adsorption effect on Sb (III).

The initial concentration is an important indicator of the effect on heavy metal removal. Firstly, preparing antimony ion solutions with 6 different initial concentrations, such as 5mg/L,10mg/L,15mg/L,20mg/L,25mg/L,30mg/L and the like, transferring the antimony ion solutions into 250ml beakers respectively, regulating the pH values of the solutions with the 6 different initial concentrations to 11 by using sodium hydroxide solutions, wherein the experiments adopt CMC synthesized under the optimal conditions, and the adding amount of the CMC in each beaker is 50mg-300 mg. And finally, placing the materials on a six-connection stirrer, carrying out an adsorption experiment at normal temperature, quickly stirring for half an hour (210r/min), slowly stirring for half an hour (60r/min), and after settling for half an hour, taking a supernatant of a water sample, and determining the concentration of antimony ions.

The effect of the initial concentration on the removal rate of antimony ions is shown in fig. 8. It can be seen from the figure that the initial concentration has a crucial influence on the removal of Sb (iii). At different initial concentrations, the removal rate always shows a steady rising trend as the CMC dosage increases. When the adding amount is 300mg, the removal rate is more than 60 percent. In addition, the CMC has obvious effect of removing antimony ions at the initial concentration of 5 mg/L. When the adding amount is 50-250mg, the removal rate is stably increased; when the amount of addition exceeds 250mg, the removal rate gradually becomes moderate. And the effect on Sb (III) is higher at any adding amount than at other concentrations. Meanwhile, when the adding amount is 300mg, the removal of Sb (III) reaches nearly 100 percent. It is also understood from the graph that the removal rate shows a decreasing tendency to various degrees as the initial concentration increases. At an initial concentration of 30mg/L, the removal rate is lower than that at other initial concentrations under 6 different addition amounts, and the removal effect of CMC on Sb (III) is reduced to the minimum.

First, 3 sets of antimony solutions each having an initial concentration of 10mg/L were prepared, each set being 6 beakers containing 200ml of the antimony solution. Then the pH values of the 3 groups of antimony solutions are respectively adjusted to 5, 7 and 11, and 300mg of CMC synthesized under the optimal condition is added. Then, after the pH is adjusted, 6 beakers in each of the 3 experiments are placed on a six-unit stirrer, the stirring time of which is adjusted to be 210min/r for fast stirring and 60min/r for slow stirring (0.5h, 1h, 1.5h, 2h, 2.5h, 3h and 3h), to carry out adsorption experiments, and the experiments are carried out at normal temperature. And finally, standing the 3 groups of adsorbed antimony solutions for half an hour for settling, separating by an external magnetic field, taking the supernatant of the solution, and detecting the residual antimony ion concentration by the method 2.2.4.

The effect of the stirring time on the Sb (iii) removal rate is shown in fig. 9. As can be seen from the figure, the effect of CMC on Sb (iii) removal becomes more and more pronounced with increasing stirring time. Firstly, under the alkaline condition, the effect of removing Sb (III) by CMC is obvious, the removal rate is increased to a certain extent with the extension of the stirring time, after the stirring time is 3 hours, the removal rate begins to gradually tend to be mild, and the removal rate reaches nearly 97 percent. Under acidic and neutral conditions, when the stirring time is 3 hours before, the removal rate is increased sharply, and the removal effect of CMC on Sb (III) is obviously changed. The removal rate is over 60 percent from 2 hours of stirring time, and gradually becomes gentle after 4 hours, and the removal rate reaches over 80 percent. From the above phenomena, the pH value may restrict the effect of CMC in removing Sb (III) to a certain extent, but the removal rate of Sb (III) under different pH values can be obviously improved along with the extension of the stirring time. Therefore, the removal effect of the CMC on the Sb (III) under the acidic and neutral conditions can be greatly promoted by changing the stirring time.

The preparation method and the properties of the composite material CMC are introduced as follows:

a preparation method of composite material CMC comprises the following steps:

s1: mixing nano Fe₃O₄Ultrasonically dispersing in a three-neck flask containing deionized water to form a suspension A;

dissolving MOFs and CS in a beaker, and fully stirring to form a stable suspension B, wherein the mass ratio of the MOFs to the CS is 1: 4-4: 1, and in the specific implementation, the mass ratio of the MOFs to the CS can be selected from 1:4, 1:2, 1:1, 2:1 or 4: 1;

s2 according to Fe₃O₄And the mass ratio of the suspension B to CS is 1: 4-4: 1, the suspension B is dropwise added into the suspension A, the suspension A is rapidly stirred to form uniform and stable suspension, and pure N is used₂Bubbling to completely deoxygenate the reaction solution, in the case of particular embodiments, Fe₃O₄The mass ratio of the CS to the CS can be selected from 1:4, 1:2, 1:1, 2:1 or 4: 1;

s3: adding initiator 2, 2-aza-bis (2-imidazoline) dihydrochloride into the reaction solution which is completely deoxidized in S2, and stirring in a constant-temperature water bath at 40-80 ℃ for 30-150 min, wherein the constant-temperature water bath temperature can be 40 ℃, 50 ℃, 60 ℃, 70 ℃ or 80 ℃, and the reaction time can be 30min, 40min, 60min, 100min, 120min, 140min or 180 min; the initiator concentration is 0.5 mmoL.L^-1～1.5mmoL·L^-1Naturally cooling and continuously crosslinking for more than 2 hours after the reaction is finished; in specific implementation, the initiator concentration can be selected to be 0.25 mmoL.L^-1、0.6mmoL·L^-1、0.8mmoL·L^-1、1.0mmoL·L^-1、1.2mmoL·L^-1、1.25mmoL·L^-1Or 1.5 mmoL.L^-1；

S4: and (3) pouring the suspension obtained in the step (S3) into a container, purifying the suspension by using absolute ethyl alcohol and distilled water for a plurality of times, separating the suspension by using a magnet, putting the separated suspension into a vacuum oven, and continuously drying the suspension in vacuum for 12 hours at the temperature of 40 ℃ until the suspension does not contain moisture, thus obtaining the composite material CMC.

As an improvement, Fe₃O₄The magnetic nanoparticles are synthesized by the following method:

weighing ferric trichloride hexahydrate and anhydrous sodium acetate, adding the ferric trichloride hexahydrate and the anhydrous sodium acetate into ethylene glycol, stirring at normal temperature to fully dissolve and mix the ferric trichloride hexahydrate and the anhydrous sodium acetate and the ethylene glycol, wherein the mass-to-volume ratio of the ferric trichloride hexahydrate to the anhydrous sodium acetate and the ethylene glycol is 1g:2.67g:37.04mL, transferring the solution into a polytetrafluoroethylene-lined high-pressure kettle, reacting for 8 hours at 200 ℃, cooling to room temperature, respectively washing for several times by using pure water and ethanol, collecting black magnetic nanoparticles by using a magnet, and finally continuously drying for 12 hours in vacuum at 60 ℃ to obtain Fe₃O₄And (3) nanoparticles. The obtained Fe₃O₄Soaking the nano particles into a prepared mixed solution of 3- (methacryloyloxy) propyl tri (trimethylsiloxane) silane and ethanol, stirring and reacting for 12 hours at 30 ℃, collecting a product under an external magnetic field, washing the product with distilled water and ethanol for several times, putting the product into a vacuum oven, adjusting the temperature to 40 ℃, and continuously drying for 12 hours to obtain Fe₃O₄Magnetic nanoparticles.

For the following examples Fe₃O₄The method of magnetic nanoparticles is specifically as follows: ferric trichloride hexahydrate (21.6g) and anhydrous sodium acetate (57.6g) were accurately weighed and added to ethylene glycol (800ml), and stirred at room temperature for 30 minutes to be sufficiently dissolved and mixed. Then transferring the solution into an autoclave with a polytetrafluoroethylene lining, reacting for 8 hours at 200 ℃, after cooling to room temperature, washing with pure water and ethanol for several times respectively, and then collecting black magnetic nanoparticles with a magnet. Finally drying was continued under vacuum at 60 ℃ for 12 hours.

Forming Fe₃O₄Nanoparticles (0.77g) were immersed in a mixed solution of 3- (methacryloyloxy) propyltris (trimethylsiloxane) silane and ethanol, which was prepared, and reacted with stirring at 30 ℃ for 12 hours. The product was then collected under an external magnetic field, washed several times with distilled water and ethanol, placed in a vacuum oven and dried for 12 hours at a temperature of 40 ℃ for further use.

Fe₃O₄Has low toxicity and biocompatibility, small particle size and relatively large surface area, and has the functions of superparamagnetism, easy modification and the like.

Nano Fe₃O₄The properties of (A) are closely related to the particle size and specific surface area thereof. Nano Fe₃O₄Has good crystallinity, surface contains carboxyl and other active groups, and has good colloid stability, low toxicity and protein resistance. Modified nano Fe₃O₄Has higher electrostatic binding affinity with anticancer drug doxorubicin hydrochloride with positive charges and has good pH release characteristic.

Nano Fe₃O₄Colloidal solutionMagnetic attraction exists in the alloy, and the alloy has obvious aggregation effect due to small particle size and nano Fe₃O₄Is easy to be oxidized in the air during the preparation process. Physical and chemical method is adopted to carry out treatment on nano Fe₃O₄The surface of the nano-Fe is modified to solve the problem of nano-Fe₃O₄The problem of agglomeration and oxidation is of great significance.

According to different classifications of modified raw materials, nano Fe₃O₄The modifying materials are generally classified into 3 types, including inorganic small molecules, organic small molecules, and organic polymers. The specific classification is shown in Table A.

Nano Fe₃O₄The catalyst has the characteristics of small particle size, large specific surface area, more surface active center points and the like, and has stronger selectivity and catalytic activity than common materials. Meanwhile, the modified nano Fe₃O₄Can be used as an anti-tumor drug carrier, and has good specificity and targeting property in the field of external magnetic field. Nano Fe modified by sodium oleate₃O₄Can be used as drug carrier for osteosarcoma chemotherapy. The magnetic field and the basic drug can be combined with the anti-cancer drug targeting the tumor body part for use, so that the physiological toxicity brought by the drug is reduced. Nano Fe₃O₄Has good biocompatibility and magnetic effect, and has wide application in tumor treatment, magnetic resonance imaging and other aspects. The application of the nano iron oxide in rat hydrocephalus CT imaging can be used as a photographic developer to analyze nano Fe₃O₄Distribution in different organs of rat, no accumulation in different organs is found, indicating that nano Fe₃O₄Has biocompatibility.

TABLE A Fe₃O₄And advantages of

Modified nano Fe₃O₄The surface reacts with heavy metal ions, can be used for removing pollutants in a water system, and is magnetic Fe₃O₄The granule has high solution separation ability and low costAn antimony contaminant adsorbent.

The MOFs are synthesized by adopting the following method:

weighing trimesic acid and FeCl hexahydrate₃Solution, benzenetricarboxylic acid and FeCl hexahydrate₃The mol ratio of the solution is 1:1, then water is added to the solution and stirred to fully dissolve the solution and uniformly mix the solution and the solution, then the mixture is added into a high-pressure kettle and placed in an oven at 200 ℃ to continuously react for 8 hours, after the mixture is cooled to room temperature, the mixture is respectively centrifuged for three times by ethanol, N-dimethylformamide and water, the centrifugation is carried out for 8 minutes at 6000 rotating speed, finally the mixture is dried in vacuum at 80 ℃ to synthesize the Fe-centered organic framework material, namely the MIFs-100 (Fe).

The specific preparation method of MOFs is as follows: accurately weigh 2.0mmol of trimesic acid and 2.0mmol of FeCl hexahydrate₃The solution was then stirred for half an hour with 60ml of water to mix well. It was then added to a 75ml autoclave and placed in an oven at 200 ℃ for a reaction time of 8 h. After cooling to room temperature, the mixture was centrifuged three times with ethanol, N-dimethylformamide and water, respectively, and centrifuged at 6000 rpm for 8 min. Finally, the organic framework material taking Fe as the center is synthesized by drying at 80 ℃ in vacuum, and the mil-100(Fe) of the organic framework is synthesized.

The MOFs synthesized by the method has good stability and can interact with functional groups such as amino groups on chitosan to form a film.

Metal-organic framework Materials (MOFs) are porous crystalline materials with unique properties such as high pore volume, regular porosity and tunable pore size due to their spatial structure, large specific surface area and pore volume, and can be widely applied to extracts. Among MOFs, Fe-based metal-organic framework materials have the advantages of high chemical stability, no toxicity, low cost, good photosensitivity and the like, and are promising photocatalysts.

Despite the numerous advantages of organometallic framework materials, they have several drawbacks in their own right. For example, the MOFs have low mechanical strength, are very insoluble in aqueous solutions and some organic solvents, and have small particle size, so that the application range is greatly limited. After the MOFs treat pollutants in water, the pollutants are difficult to recycle, and secondary pollution is easily caused.Therefore, functional modifications to MOFs are important. Fe₃O₄The magnetic material is combined with the MOFs, so that on one hand, the two adsorption materials are combined together, the removal effect on pollutants can be greatly improved, and the adsorption capacity is increased; on the other hand, the magnetic substance is introduced into the organic metal framework material, so that the defects that MOFs are difficult to recover and easily cause environmental pollution can be well overcome, and the cost is saved.

In order to illustrate the chemical properties of the composite material CMC prepared by the invention and the application of the composite material CMC in removing metal Sb, the invention adopts an adsorption test method to test the removal rate of the composite material CMC on the metal Sb (III), so that an antimony ion solution is specially prepared, a stirrer 210r/min is adopted to stir for 30min, a stirrer 60r/min is adopted to stir for 30min, after half an hour of precipitation, a magnet is used for separating an adsorption material, and a water sample at 2cm of a supernatant is taken by a 0.45 mu m filter membrane to measure the concentration of the Sb (III).

Preferably, the Fe₃O₄: CS: the MOFs is prepared by mixing the following components in a mass ratio of 1: 2: 2.

provided with Fe₃O₄The quality of the CMC is a fixed value, the reaction temperature is 60 ℃, the pH value is 6.2, the reaction time is 1 hour, CMC with different properties is prepared by changing the mixture ratio of CS and MOFs, after the preparation reaction is finished, an external magnetic field is used for separation, and the CMC is dried for 12 hours, which is shown in examples 1 to 5:

composite CMC was prepared according to the above preparation method of composite CMC, except for the selection of the respective parameters S1, S2 and S3, as shown in table 1:

TABLE 1

An adsorption test was performed using 10mg/L of the prepared antimony solution as test water, and the removal rate of Sb (III) was determined, as shown in FIG. 1: as can be seen, CMC has a significant effect on Sb (III) removalAnd (5) fruit. The removal effect of the metal antimony is reduced along with the reduction of the ratio of CS to MOFs, and the removal rate of Sb (III) is increased firstly and then reduced. When the ratio of CS to MOFs is 1: at 1 time, Fe₃O₄The CS-MOFs has the best effect on removing Sb (III) and has the highest removal rate; when the ratio of CS to MOFs reaches 1: after 1, in the investigation range, whether the ratio of CS to MOFs is increased or reduced, the removal rate of Sb (III) has an obvious descending trend, and when the ratio of CS to MOFs is 1: at 4, the effect of removing antimony ions is minimal. Meanwhile, it can be seen from the figure that when the specific gravity occupied by CS or MOFs is too large, the Sb (iii) removal effect is greatly affected. In summary, the ratio of CS to MOFs is 1:1 is the best mixture ratio.

Setting the mass ratio of CS to MOFs as 1:1, the reaction temperature is 50 ℃, the reaction time is 60min, the pH value is 6.2, and Fe with different mixture ratios is used₃O₄And CS, preparing CMC, after the preparation reaction is completed, separating by using an external magnetic field, and drying for 12 hours, see examples 6 to 10.

Composite CMC was prepared according to the above preparation method of composite CMC, except for the selection of the respective parameters S1, S2 and S3, as shown in table 2:

TABLE 2

An adsorption test was performed using 10mg/L of the prepared antimony solution as test water, and the removal rate of Sb (III) was determined, the results of which are shown in FIG. 2: fe₃O₄The effect of the ratio of C to CS on the Sb (III) removal rate is shown in FIG. 2. As can be seen, with Fe₃O₄And the CS ratio is reduced, and the Sb (III) removal rate shows a curve that the Sb (III) removal rate is increased and then reduced. When Fe₃O₄And the ratio of CS is from 4: reduction of 1 to 2:1, the removal rate is increased sharply; and when the ratio thereof is from 2:1 is reduced to 4: when 1, the increasing trend of the removal rate tends to be gentle, and the increasing rate is about 1 percent; when the ratio of 1:1 continues to decrease to 1:2, the growth rate is sharply increased while in Fe₃O₄And CS is 1: at 2 timeThe removal rate is highest; when the mixture ratio is reduced to 1: at 4, the growth rate had a tendency to slide down sharply. Thus, Fe as described above₃O₄: CS: the optimal mass ratio of the three materials of the MOFs is 1: 2: 2.

as a modification, the temperature of the thermostatic water bath is 60 ℃.

Taking Fe in example 9₃O₄: CS: the optimal proportion of the three MOFs materials is 1: 2: 2, reaction time of 60min, pH 6.2, preparing CMC at different water bath temperatures ranging from 40 ° to 80 °, after the reaction is finished, separating with a magnet, and then drying under vacuum for 12 hours, see examples 11 to 15.

Composite CMC was prepared according to the above preparation method of composite CMC, except for the selection of the respective parameters S1, S2 and S3, as detailed in table 3.

TABLE 3

Taking Fe₃O₄: CS: the optimal mass ratio of the three materials of the MOFs is 1: 2: and 2, reacting for 60min, wherein the pH value is 6.2, preparing the CMC at different water bath temperatures, wherein the reaction temperature ranges from 40 ℃ to 80 ℃, separating by using a magnet after the reaction is finished, and drying for 12 hours under a vacuum condition.

An adsorption test was carried out using 10mg/L of the prepared antimony solution as test water, and the Sb (III) removal rate was measured, the results of which are shown in FIG. 3.

The effect of the reaction temperature on the Sb (iii) removal rate is shown in fig. 3. As can be seen from the graph, the reaction temperature has a large influence on the removal of antimony ions, and the removal rate tends to increase first and then decrease as the reaction temperature increases. When the reaction temperature is increased from 40 ℃ to 60 ℃, the removal rate has a remarkable increasing trend, and when the reaction temperature reaches 60 ℃, the removal rate is increased to the maximum; in the changing process that the reaction temperature exceeds 60 ℃ and is continuously increased to 80 ℃, the removal rate is sharply reduced, and when the reaction temperature is 80 ℃, the removal rate is reduced to the minimum. Therefore, 60 ℃ is taken as the optimal reaction temperature.

As an improvement, the reaction time of the thermostatic waterbath is 90 min.

Taking Fe in example 9₃O₄: CS: the optimal ratio of the three MOFs materials is 1: 2: and 2, preparing the CMC at the reaction temperature of 60 ℃ and the pH value of 6.2 under different reaction times, wherein the reaction time ranges from 30min to 150 min. After the reaction was completed, the reaction mixture was separated with a magnet and then dried under vacuum at 60 ℃ for 12 hours, as in examples 16 to 20.

Composite CMC was prepared according to the above preparation method of composite CMC, except for the selection of the respective parameters S1, S2 and S3, as shown in table 4:

TABLE 4

An adsorption test was carried out using 10mg/L of the prepared antimony solution as test water, and the Sb (III) removal rate was measured, the result of which is shown in FIG. 4.

The effect of the reaction time on the Sb (iii) removal rate is shown in fig. 4. From the figure, it can be seen that the reaction time has a large influence on the removal rate of metallic antimony. The removal rate peaks with increasing reaction time, so that a suitable reaction time is required for the synthesis of CMC. When the reaction time is increased from 30min to 90min, the removal rate is obviously increased, which may be that in the stage, the generated active free radicals are gradually increased, and the unreacted components are more, so that the removal rate of Sb (III) is correspondingly increased. And when the reaction time exceeds 90min, the active free radicals in the system are gradually reduced, and the unreacted components are also reduced, so that the polymerization degree of the components is reduced, and the removal rate of Sb (III) is correspondingly reduced. Therefore, 90min is taken as the optimal reaction time. As an improvement, the concentration of the initiator in the reaction system is 1.25 mmoL.L^-1。

Taking Fe in example 9₃O₄: CS: the optimal ratio of the three material components of the MOFs is 1: 2: 2, the reaction temperature is 60 ℃, the pH value is 6.2, and the reaction time isPreparing CMC at different initiator concentrations of 0.5 mmoL.L for 90min^-1～1.25mmoL·L^-1. After the reaction was completed, it was separated with a magnet and then dried under vacuum at 60 ℃ for 12 hours, see examples 21 to 25.

Composite CMC was prepared according to the above preparation method of composite CMC, except for the selection of the respective parameters S1, S2 and S3, see in particular table 5.

TABLE 5

An adsorption test was carried out using 10mg/L of the prepared antimony solution as test water, and the Sb (III) removal rate was measured, the results of which are shown in FIG. 5.

The effect of initiator concentration on Sb (iii) removal rate is shown in fig. 5 above. It can be seen from the figure that the initiator concentration also has a significant effect on the removal rate, and that the Sb (iii) removal rate increases and then decreases with increasing initiator concentration, indicating that there is also a suitable range for the initiator concentration. When the initiator concentration is from 0.5 mmoL.L^-1Increase to 1.25 mmoL.L^-1Shows a steady rising trend in the Sb (III) removal rate during the change, and increases to 1.25 mmoL.L in the initiator concentration^-1The removal rate is highest; when the concentration of the initiator exceeds 1.25 mmoL.L^-1In this case, the Sb (iii) removal rate showed a sharp decrease. Therefore, 1.25 mmoL.L is taken^-1For optimal initiator concentration.

Magnetic Properties of CMC

Referring to fig. 6, the magnetic field strength of all three materials rises slowly with the increase of the magnetic field, and the influence of the magnetic field strength is obvious. Wherein Fe₃O₄The magnetization intensity of the magnetic field has obvious effect under the action of the magnetic field, and in the process of increasing the magnetic field, Fe₃O₄The magnetization of (a) begins to slowly approach equilibrium. When the magnetic field extends forwards, the maximum saturation magnetic strength value of the three materials is 98.9 emu/g; the maximum saturation magnetic strength value is-98.9 emu/g when the magnetic field extends reversely. In contrast to Fe₃O₄The magnetization of the final product CMC is somewhat reduced, but the forward saturation magnetization is still 20.6emu/g, and the reverse and magnetization are-20.6 emu/g. The possible reasons are: fe₃O₄As a monomer of polymer, during the synthesis of CMC, part of Fe is lost by heating and stirring reaction₃O₄Magnetic strength of, or part of Fe₃O₄During the polymerization reaction for preparing CMC, the CMC is coated with other matters and has small property change, so that the original magnetic strength is weakened. Meanwhile, as can be seen from the figure, the hysteresis loop of the CMC after the adsorption of the heavy metal antimony is basically the same as that of the CMC before the adsorption, which shows that the magnetic strength of the CMC in the process of the adsorption of the heavy metal antimony is not changed, the magnetic strength is stable, and the CMC is favorable for separation from the water body after the adsorption of the heavy metal antimony. Further, Fe₃O₄The curves of the materials all resemble the "S" hysteresis curves in the soft magnetic range, which indicates that the Fe synthesized₃O₄The material is super magnetic.

Finally, the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all of them should be covered in the claims of the present invention.

Claims

1. A method for removing antimony ions in a water body by using composite material CMC is characterized by comprising the following steps: the method comprises the following steps:

s1: pretreating a water body:

adjusting the pH value of the water body to make the water body alkaline;

s2: adding composite material CMC into the water body, and stirring: the ratio of the adding amount of the composite material CMC to the volume of the water body is as follows: 0.2 g/L-1.2 g/L, the adding mass of the composite material CMC and the volume unit of the water body are required to be on an order of magnitude; then quickly stirring for 0.5-3 h, slowly stirring for 0.5-3 h, finally standing for more than 30min, and separating the adsorbent by an external magnetic field;

the preparation method of the composite material CMC comprises the following steps:

1) mixing nano Fe₃O₄Ultrasonically dispersing in a three-neck flask containing deionized water to form a suspension A;

dissolving MOFs and CS in a beaker, and fully stirring to form a stable suspension B, wherein the mass of the MOFs and the CS is 1:4, 1:2, 1:1, 2:1 or 4: 1;

2) dropwise adding the suspension B into the suspension A, rapidly stirring to form uniform and stable suspension, and adding pure N₂Bubbling to deoxidize the reaction solution completely, and obtaining nano Fe₃O₄And CS in a mass ratio of 1:4, 1:2, 1:1, 2:1 or 4: 1;

3) adding initiator 2, 2-aza-bis (2-imidazoline) dihydrochloride into the completely deoxidized reaction solution in the step 2), and stirring in a constant-temperature water bath at the temperature of 40 ℃, 50 ℃, 60 ℃, 70 ℃ or 80 ℃ for 30min, 40min, 60min, 100min, 120min or 140 min; after the reaction is finished, the mixture is naturally cooled and continuously crosslinked for more than 2 hours, and the initiator concentration is 0.6 mmoL.L^-1、0.8mmoL·L^-1、1.0mmoL·L^-1、1.2mmoL·L^-1、1.25mmoL·L^-1Or 1.5 mmoL.L^-1；

4) Pouring the suspension obtained in the step 3) into a container, purifying the suspension by using absolute ethyl alcohol and distilled water for a plurality of times, separating the suspension by using a magnet, putting the separated suspension into a vacuum oven, and continuously drying the suspension in vacuum for 12 hours at the temperature of 40 ℃ until the suspension does not contain moisture, thus obtaining the composite material CMC;

the nano Fe₃O₄The method comprises the following steps:

weighing ferric trichloride hexahydrate and anhydrous sodium acetate, adding the ferric trichloride hexahydrate and the anhydrous sodium acetate into ethylene glycol, stirring at normal temperature to fully dissolve and mix the ferric trichloride hexahydrate and the anhydrous sodium acetate and the ethylene glycol, wherein the mass-to-volume ratio of the ferric trichloride hexahydrate to the anhydrous sodium acetate and the ethylene glycol is 1g:2.67g:37.04mL, transferring the solution into a polytetrafluoroethylene-lined high-pressure kettle, reacting for 8 hours at 200 ℃, respectively washing with pure water and ethanol for several times after cooling to room temperature, and collecting black with a magnetMagnetic nanoparticles, finally dried for 12 hours in vacuum at 60 ℃ to obtain Fe₃O₄Nanoparticles of Fe to be obtained₃O₄Soaking the nano-particles into a prepared mixed solution of 3- (methacryloyloxy) propyl tri (trimethylsiloxane) silane and ethanol, stirring and reacting for 12 hours at 30 ℃, collecting a product under an external magnetic field, washing the product with distilled water and ethanol for several times, putting the product into a vacuum oven, adjusting the temperature to 40 ℃, and continuously drying for 12 hours to obtain the nano-Fe₃O₄；

The MOFs are synthesized by adopting the following method:

weighing trimesic acid and FeCl hexahydrate₃Solution, trimesic acid and FeCl hexahydrate₃The mol ratio of the solution is 1:1, then water is added to the solution and stirred to fully dissolve the solution and uniformly mix the solution and the solution, then the mixture is added into a high-pressure kettle and placed in an oven at 200 ℃ to continuously react for 8 hours, after the mixture is cooled to room temperature, the mixture is respectively centrifuged for three times by ethanol, N-dimethylformamide and water, the centrifugation is carried out for 8 minutes at 6000 rotating speed, finally the mixture is dried in vacuum at 80 ℃ to synthesize the Fe-centered organic framework material, namely the MIFs-100 (Fe).

2. The method for removing antimony ions from a water body by using the composite material CMC as claimed in claim 1, wherein: and in the step S1, the pH value of the water body is adjusted to 11-12, so that the water body is strong in alkalinity.

3. The composite CMC of claim 1 or 2, wherein the method for removing antimony ions from a water body comprises: and diluting the water body in the S1 to reduce the metal Sb in the water body, so that the concentration of the metal Sb in the water body is 5-30 mg/L.

4. The method for removing antimony ions from a water body by using the composite material CMC as claimed in claim 3, wherein: and diluting the water body in the S1 to ensure that the concentration of the metal Sb in the water body is 5 mg/L.

5. The method for removing antimony ions from a water body by using the composite material CMC as claimed in claim 2, wherein: the ratio of the rotating speed of the rapid stirring to the rotating speed of the slow stirring is 3.5: 1.

6. the method for removing antimony ions from a water body by using the composite material CMC as claimed in claim 5, wherein: in the step S2, the mixture is stirred rapidly for 2 hours and then slowly for 2 hours.