Fiber-based adsorption material, preparation method thereof and removal of trivalent chromium in water body
Technical Field
The invention belongs to the field of heavy metal wastewater treatment, and particularly relates to a fiber-based adsorption material, a preparation method thereof and removal of trivalent chromium in a water body.
Background
A series of dyeing treatments exist in industries such as tanning, metal processing, electroplating and the like, and due to the wide use of heavy metal-containing dyes, a large amount of produced dyeing wastewater contains a large amount of heavy metal pollutants, wherein chromium is the most toxic and is the most difficult to treat. Because chromium belongs to the first category of priority control pollutants, the national environmental protection standard requires separate diversion chromium removal treatment, if the chromium is not treated or is not treated, the chromium is discharged, river water and underground water are seriously polluted, farmland and human health are harmed, and huge harm is generated to ecological environment and human survival. Therefore, it is important to study the treatment of chromium-containing wastewater. The chromium-containing wastewater is treated by a plurality of methods, and currently, an electrolytic method, a chemical method, an ion exchange method, a membrane separation method and the like are commonly used. Wherein, the chemical method needs to add excessive medicament to easily cause secondary pollution and generate large amount of sludge. The ion exchange method is to use the high molecular synthetic resin to exchange ions with chromium in the wastewater, and has the disadvantages of high cost, complex operation management, difficult resin regeneration and short service life. The membrane separation method has the problems of electrodialysis, reverse osmosis, electrodeionization and the like, the service life and the cost of the membrane are still in the stage of research and trial, the electrolysis method is widely applied due to the characteristics of small volume, small occupied area, low power consumption, convenient management, good effect and the like, but the chromium-containing wastewater treated by the electrolysis technology is difficult to reach the discharge standard, the energy consumption is increased linearly for the wastewater with lower chromium concentration, and the method is not economical and feasible from the cost perspective.
Disclosure of Invention
The invention aims to overcome the defects of high treatment cost of chromium-containing wastewater, difficult resin regeneration and short service life in the prior art, and provides a fiber-based adsorbing material (material A) which can adsorb trivalent chromium in an aqueous solution and has higher adsorption rate and longer service life compared with the adsorbing material in the prior art.
Except for special description, the parts are parts by weight, and the percentages are mass percentages.
The invention adopts the following technical scheme:
a fiber-based adsorption material (material A) is characterized in that the fiber-based adsorption material is prepared by the reaction of amino fiber and perfluorooctanoic acid under the action of a condensing agent Dicyclohexylcarbodiimide (DCC) for 8-16h at the temperature of 50-80 ℃; the amino fiber is prepared by irradiation grafting of polypropylene.
Further, the amino fiber adopts the following preparation method: (1) pretreatment: washing polypropylene with acetone, then washing with deionized water, and drying at 50 ℃ for later use; (2) pre-irradiation: pre-irradiating the polypropylene fiber in air for 6h by adopting an electron beam, wherein the irradiation step is completed by adopting an ELV-8 type electron accelerator; (3) irradiation grafting: weighing 10g of pre-irradiated fiber, placing the fiber in a 100mL flask, adding 50mL of mixed solution of methanol and allyl amine (V/V = 1), irradiating and grafting for 4h at 50 ℃, and washing with ethanol after the reaction is finished, thus obtaining the amino fiber of the invention.
According to a second aspect of the present invention, the present invention provides a method for producing the above-described fiber-based adsorbent material (material a).
The preparation method of the fiber-based adsorption material (material A) adopts the following steps:
(1) Pretreatment: washing polypropylene with acetone, then washing with deionized water, and drying at 50 ℃ for later use;
(2) Pre-irradiation: pre-irradiating the polypropylene fiber in air for 6 hours by adopting an electron beam, wherein the irradiation step is completed by adopting an ELV-8 type electron accelerator;
(3) Irradiation grafting: weighing 10g of pre-irradiated fiber, placing the fiber in a 100mL flask, adding 50mL of a mixed solution of methanol and allyl amine (V/V = 1), irradiating and grafting the fiber for 4h at 50 ℃, and washing the fiber by using ethanol after the reaction is finished to obtain amino fiber;
(4) Chemical grafting: dissolving amino fiber by using N, N-Dimethylformamide (DMF), then adding perfluorooctanoic acid and a condensing agent Dicyclohexylcarbodiimide (DCC), reacting for 12 hours at the temperature of 60 ℃, fully washing by using ethanol after the reaction is finished, and drying at the temperature of 50 ℃ to obtain the fiber-based adsorbing material.
According to a third aspect of the invention, the invention provides the use of the above-described fibre-based adsorption material (material a) in the treatment of trivalent chromium-containing waste water.
According to a fourth aspect of the present invention, the present invention provides a fiber-based adsorbent material (material B) that adsorbs trivalent chromium in aqueous solutions with higher adsorption rates and lifetimes relative to prior art adsorbent materials.
A fiber-based adsorption material (material B) is characterized in that the fiber-based adsorption material is prepared by the reaction of amino fiber and trifluorobenzoic acid for 10-18h at the temperature of 50-80 ℃ under the action of a condensing agent Dicyclohexylcarbodiimide (DCC);
the preparation method of the amino fiber is the same as that of the amino fiber, and the amino fiber is prepared by polypropylene irradiation grafting.
According to a fifth aspect of the present invention, there is provided a method for producing the above-mentioned fiber-based adsorbent material (material B).
The preparation method of the fiber-based adsorbing material (material B) adopts the following steps:
(1) Pretreatment: washing polypropylene with acetone, then washing with deionized water, and drying at 50 ℃ for later use;
(2) Pre-irradiation: pre-irradiating the polypropylene fiber in air for 6h by adopting an electron beam, wherein the irradiation step is completed by adopting an ELV-8 type electron accelerator;
(3) Irradiation grafting: weighing 10g of pre-irradiated fiber, placing the fiber in a 100mL flask, adding 50mL of mixed solution of methanol and allyl amine (V/V = 1), irradiating and grafting for 4h at 50 ℃, and washing with ethanol after the reaction is finished to obtain amino fiber;
(4) Chemical grafting: dissolving amino fiber with N, N-Dimethylformamide (DMF), adding trifluorobenzoic acid and a condensing agent Dicyclohexylcarbodiimide (DCC), reacting for 16h at 60 ℃, fully washing with ethanol after the reaction is finished, and drying at 50 ℃ to obtain the fiber-based adsorbing material.
According to a sixth aspect of the present invention, the present invention provides the use of the above-described fiber-based adsorbing material (material B) in the treatment of wastewater containing trivalent chromium.
Has the advantages that:
the invention provides a fiber-based adsorption material, which is prepared by taking polypropylene as a matrix, firstly introducing amino in an irradiation grafting manner and then chemically grafting. The surface of the adsorption material prepared by the invention has stronger electrostatic attraction, and the deep removal of trivalent chromium in a water body can be realized. The preparation method is simple and suitable for industrial production. The method has the advantages of low operation cost, simple operation and stable operation, and the adsorbing material can be regenerated and recycled, so that the trivalent chromium-containing wastewater can be discharged up to the standard, and the chromium ions in the wastewater can be recovered, thereby realizing the resource utilization of the trivalent chromium-containing wastewater.
Drawings
FIG. 1 is a scanning electron micrograph of a commercial polypropylene;
FIG. 2 is a scanning electron micrograph of a fiber-based adsorbent material (Material A) prepared in example 2;
FIG. 3 is an infrared spectrum of the fiber-based adsorbent material (Material A) prepared in example 2;
FIG. 4 is a scanning electron micrograph of a fiber-based adsorbent material (Material B) prepared in example 3;
FIG. 5 is an infrared spectrum of the fiber-based adsorbent material (material B) prepared in example 3;
FIG. 6 is a statistical chart of the adsorption capacity of the fiber-based adsorbent (Material A) as an adsorbent for trivalent chromium in wastewater in example 4;
FIG. 7 is a statistical chart of the adsorption capacity of the fiber-based adsorbent (Material B) as an adsorbent for trivalent chromium in wastewater in example 5.
Detailed Description
The present invention is described in detail below with reference to specific examples, which are given for the purpose of further illustrating the invention and are not to be construed as limiting the scope of the invention, and the invention may be modified and adapted by those skilled in the art in light of the above disclosure. The raw materials and reagents used in the invention are all commercial products.
Example 1
Preparation of amino fibres
(1) The pretreatment method comprises the following steps: commercial polypropylene (9 mm, from the firm-maturing Xibo fiber Co., ltd.) was washed with acetone several times, then washed with deionized water several times, and then dried at 50 ℃ for use.
(2) Pre-irradiation: before introducing amino group by irradiation grafting, the polypropylene fiber is pre-irradiated for 6h in the air by adopting an electron beam, and the irradiation step is completed by adopting an ELV-8 type electron accelerator.
(3) Irradiation grafting (amino is introduced on the surface of the fiber to form amino fiber): weighing 10g of pre-irradiated fiber, placing the fiber in a 100mL flask, adding 50mL of mixed solution of methanol and allyl amine (V/V = 1), irradiating and grafting for 4h at 50 ℃, washing the fiber for multiple times by using ethanol after the reaction is finished, and removing unreacted raw materials to obtain amino fiber, wherein the weight gain rate is about 15%.
Example 2
Preparation of fiber-based adsorbent Material (Material A)
Weighing 10g of amino fiber prepared according to the method in the embodiment 1, placing the amino fiber in a 100ml three-neck flask, adding 50ml of N, N-Dimethylformamide (DMF), adding 4.3g of perfluorooctanoic acid and 1.0g of Dicyclohexylcarbodiimide (DCC), reacting for 12h at 60 ℃, fully washing with ethanol after the reaction is finished, and drying at 50 ℃ to obtain the target product, namely the fiber-based adsorption material (material A). The scanning electron microscope of the fiber-based adsorbent material (material a) fiber prepared in example 2 is shown in fig. 2, and the fiber is significantly different from the scanning electron microscope of the commercial polypropylene (fig. 1). The IR spectrum of the fiber-based adsorbent material (material A) prepared in example 2 is shown in FIG. 3, and it is apparent from the IR spectrum that amino groups, carbonyl groups and fluorine-containing groups were introduced.
Example 3
Preparation of fiber-based adsorbent Material (Material B)
Weighing 10g of amino fiber prepared according to the method in the embodiment 1, placing the amino fiber in a 100ml three-neck flask, adding 50ml of N, N-Dimethylformamide (DMF), adding 5.5g of trifluorobenzoic acid and 1.0g of Dicyclohexylcarbodiimide (DCC) to react for 16h at the temperature of 60 ℃, fully washing the amino fiber with ethanol after the reaction is finished, and drying the amino fiber at the temperature of 50 ℃ to obtain a target product, namely a fiber-based adsorption material (material B). The scanning electron microscope of the fiber-based adsorbent material (material B) fiber prepared in example 3 is shown in fig. 4, and the fiber is significantly different from the scanning electron microscope of commercial polypropylene (fig. 1). The infrared spectrum of the fiber-based adsorbent material (material B) prepared in example 3 is shown in FIG. 5, and it is apparent from the infrared spectrum that amino groups, carbonyl groups and fluorine-containing groups were introduced.
Example 4
2.0g of the fiber-based adsorbent material (material A) prepared according to the method of example 2 was weighed as a fiber adsorbent material, and loaded in an adsorption column having a diameter of 10mm and a height of 10cm, and subjected to Cr-containing adsorption in a manner of bottom-in-top-out 3+ And (5) carrying out adsorption treatment on the aqueous solution. The adsorption results are shown in table 1 below; for Cr 3+ Maximum dynamic adsorption capacity ofAs shown in FIG. 6, for Cr 3+ The maximum dynamic adsorption capacity of the catalyst can reach 218mg/g, and Cr in effluent liquid 3+ The content is less than 0.3ppm, and reaches Cr in the sewage discharge standard 3+ And (4) requiring.
TABLE 1 Cr in the effluent at different adsorption times 3+ Concentration of
Example 5
2.0g of the fiber-based adsorbing material (material B) prepared according to the method of example 3 was weighed as a fiber adsorbing material, and the fiber adsorbing material was filled in an adsorbing column having a diameter of 10mm and a height of 10cm, and the adsorption column containing Cr was aligned in a manner of bottom-in and top-out 3+ And (5) carrying out adsorption treatment on the aqueous solution. The adsorption results are shown in table 2 below; for Cr 3+ The maximum dynamic adsorption capacity of (d) is shown in fig. 7.
TABLE 2 Cr in the effluent at different adsorption times 3+ Concentration of
The material is used for treating Cr under the condition that 1.5mol/L hydrochloric acid is used as an eluent 3+ The maximum dynamic saturated adsorption capacity can reach 192mg/g and can reach 184mg/g after repeated use for 6 times, and the Cr in the effluent liquid 3+ The content is less than 0.3ppm, and reaches Cr in the sewage discharge standard 3+ The requirements of (1).