Chromium-containing wastewater adsorption material and preparation method thereof

Abstract

The present application relates to a kind of chromium-containing wastewater adsorption material and its preparation method, belong to heavy metal ion adsorption material technical field.The preparation method of chromium-containing wastewater adsorption material of the present application includes the following steps: first, cellulose acetate fiber and phenylenediamine are subjected to Schiff base reaction, then oxidation polymerization reaction is carried out under the action of oxidizing agent, and chromium-containing wastewater adsorption material is obtained.The preparation method of chromium-containing wastewater adsorption material of the present application is simple and easy to operate, by adjusting the proportion of cellulose acetate fiber and phenylenediamine monomer and the reaction time of cellulose acetate fiber and phenylenediamine monomer, the size and distribution of polyphenylene diamine nanoparticles can be adjusted.The chromium-containing wastewater adsorption material prepared by the present application has the fiber morphology of cellulose acetate fiber, and the adsorption capacity of Cr (Ⅵ) can reach 434.78 mg / g.

Description

TECHNICAL FIELD

[0001] The application relates to a chromium-containing wastewater adsorption material and a preparation method thereof, and belongs to the technical field of heavy metal ion adsorption materials. BACKGROUND

[0002] Chromium-containing wastewater is a main pollutant discharged by electroplating, tanning and metallurgy industries, and the discharge amount is increasing with the acceleration of industrialization in recent years. Among them, Cr(Ⅵ) poses a great threat to the ecological environment and human health due to its strong physiological toxicity and the ability to enrich along the food chain. At present, the main treatment methods for Cr(Ⅵ) wastewater include adsorption, chemical precipitation, electrochemical reduction, flocculation and microbial degradation. Among them, the adsorption method is one of the main methods preferred in practical application due to the advantages of simple operation, easy separation and recovery, low cost and no secondary pollution. The adsorption efficiency of Cr(Ⅵ) mainly depends on the performance of the adsorbent, therefore, developing a chromium-containing wastewater adsorption material with large adsorption capacity, high efficiency, environmental protection and wide source has become the main task and research focus of treating chromium-containing wastewater.

[0003] Polyaromatic amines have gradually attracted attention due to the advantages of high functional group density, stable structure and high Cr(Ⅵ) adsorption performance. Among them, polyphenylenediamine exhibits unique high adsorption capacity and selectivity in adsorbing Cr(VI). Moreover, the morphology of the polymer can be changed by changing the reaction conditions or adding specific active reagents. Polyphenylenediamine is mostly nanoparticles (including spherical nanoparticles, nanobands, nanorods, nanofibers, etc.), which is beneficial to full contact with pollutants and increases the mass transfer rate. However, polyphenylenediamine nanoparticles are difficult to recover due to their small size, which may cause secondary pollution and increase the use cost. Moreover, polyphenylenediamine nanoparticles are prone to agglomeration, resulting in low adsorption efficiency of Cr(VI). SUMMARY

[0004] The purpose of the present application is to provide a preparation method of a chromium-containing wastewater adsorption material, which can solve the problem of low adsorption efficiency of the currently prepared polyaromatic amine chromium-containing wastewater adsorption material.

[0005] Another purpose of the present application is to provide a chromium-containing wastewater adsorption material, which can solve the problem of low adsorption efficiency of the currently prepared polyaromatic amine chromium-containing wastewater adsorption material.

[0006] In order to achieve the above purposes, the technical scheme adopted by the preparation method of the chromium-containing wastewater adsorption material of the present application is as follows:

[0007] The preparation method of the chromium-containing wastewater adsorption material comprises the following steps: first, Schiff base reaction is performed on cellulose acetate fibers and phenylenediamine, and then oxidation polymerization reaction is performed under the action of an oxidizing agent to obtain the chromium-containing wastewater adsorption material.

[0008] The preparation method of the chromium-containing wastewater adsorption material of the present application grafts the phenylenediamine monomer onto the cellulose acetate fiber through Schiff base reaction to obtain a complex, and then realizes in-situ polymerization of the polypyridine nanoparticles on the cellulose acetate fiber by using the amino group on the complex and the oxidative polymerization reaction of the amino group in the phenylenediamine monomer, thereby improving the uniformity of the polypyridine nanoparticles on the cellulose acetate fiber and avoiding agglomeration of the polypyridine nanoparticles. The preparation method of the chromium-containing wastewater adsorption material of the present application is simple and easy to operate, and the particle size and distribution of the polypyridine nanoparticles can be adjusted by adjusting the ratio of the cellulose acetate fiber and the phenylenediamine monomer and the reaction time of the cellulose acetate fiber and the phenylenediamine monomer. The chromium-containing wastewater adsorption material prepared by the present application has the fiber morphology of the cellulose acetate fiber, and the adsorption capacity of Cr(Ⅵ) can reach 434.78 mg / g.

[0009] Preferably, the mass ratio of the phenylenediamine to the cellulose acetate fiber is 1:(1-50).

[0010] Preferably, the mass ratio of the phenylenediamine to the cellulose acetate fiber is 1:(10-20).

[0011] Preferably, the time of the Schiff base reaction is 0.5-3 h.

[0012] Preferably, the phenylenediamine is m-phenylenediamine.

[0013] Preferably, the molar ratio of the phenylenediamine to the oxidizing agent is 1:(1-3).

[0014] Preferably, the oxidizing agent is potassium persulfate, sodium persulfate, ammonium persulfate, hydrogen peroxide or ferric chloride.

[0015] Preferably, the oxidizing agent is added in the form of a solution, and the pH of the reaction system is controlled to be 4-7 during the process of adding the oxidizing agent and the oxidative polymerization reaction.

[0016] Preferably, the cellulose acetate fiber is prepared by a method comprising the following steps: ultrasonic dispersion of cigarette filter fibers and water, solid-liquid separation, washing, impurity removal by soaking the washed solid in lye, then washing the soaked solid, freeze-drying to obtain cellulose acetate fiber; the cigarette filter fibers are fiber bundles with a length of 0.5-1 cm and a diameter of 1-5 μm.

[0017] The technical scheme of the chromium-containing wastewater adsorption material of the present application is as follows:

[0018] A chromium-containing wastewater adsorption material prepared by the preparation method of the chromium-containing wastewater adsorption material as described above.

[0019] The chromium-containing wastewater adsorption material of the present application comprises cellulose acetate fibers and polyphenylene diamine nanoparticles chemically bonded on the cellulose acetate fibers, has a fiber form, can avoid agglomeration of the polyphenylene diamine nanoparticles during use, has a Cr(Ⅵ) adsorption capacity of 434.78 mg / g, and is easy to recover. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 Scanning electron microscope images of the chromium-containing wastewater adsorption materials prepared in Examples 1-9 of the present application;

[0021] Figure 2 Transmission electron microscope image of the chromium-containing wastewater adsorption material prepared in Example 8 of the present application;

[0022] Figure 3 Infrared spectra of cellulose acetate, poly-m-phenylene diamine and the chromium-containing wastewater adsorption materials prepared in Examples 1-6 of the present application;

[0023] Figure 4 Raman spectra of the chromium-containing wastewater adsorption materials prepared in Examples 1-5 of the present application;

[0024] Figure 5 Raman spectrum area scan of the chromium-containing wastewater adsorption materials prepared in Examples 1-9 of the present application;

[0025] Figure 6 Saturated adsorption capacity of the chromium-containing wastewater adsorption materials prepared in Examples 1-9 of the present application for Cr(Ⅵ) in K2Cr2O7 solutions with different concentrations;

[0026] Figure 7 Adsorption kinetics experimental results of the chromium-containing wastewater adsorption materials prepared in Examples 1-9 of the present application for Cr(Ⅵ) in K2Cr2O7 solutions;

[0027] Figure 8 Saturated adsorption capacity of the chromium-containing wastewater adsorption material prepared in Example 8 of the present application for Cr(Ⅵ) in K2Cr2O7 solutions with different pH values;

[0028] Figure 9 Recovery and regeneration test of the chromium-containing wastewater adsorption material prepared in Example 8 of the present application. DETAILED DESCRIPTION

[0029] The present invention's method for preparing a chromium-containing wastewater adsorbent material is a groundbreaking invention. Addressing the current problem of polyphenylenediamine nanoparticles easily agglomerating, resulting in low Cr(VI) adsorption efficiency, the method grafts polyphenylenediamine nanoparticles onto cellulose acetate molecular chains to prevent agglomeration and improve their uniformity of dispersion, thereby enhancing the material's Cr(VI) adsorption efficiency.

[0030] The polyphenylenediamine nanoparticles in the present invention are obtained by polymerizing phenylenediamine monomers. The structure and reaction mechanism of the polymer are as follows:

[0031]

[0032] The preparation method of the chromium-containing wastewater adsorbent material of the present invention comprises the following steps: subjecting the amino groups in the phenylenediamine monomer and the carbonyl groups on the cellulose acetate fiber to a Schiff base reaction to obtain a composite, and then subjecting the amino groups on the composite and the amino groups in the phenylenediamine monomer to an oxidative polymerization reaction under the action of an oxidant to obtain the chromium-containing wastewater adsorbent material.

[0033] In the present invention, the cellulose acetate fiber can be obtained from the market or prepared from cigarette filter fibers.

[0034] In some preferred embodiments, the cellulose acetate fiber is prepared by a method comprising the following steps: ultrasonically dispersing cigarette filter fibers and water, separating the solid and the liquid, washing, soaking the washed solid in an alkali solution, then washing the soaked solid, and freeze-drying to obtain the cellulose acetate fiber; the soaking temperature is 50 to 90° C., and the time is 6 to 12 hours; the alkali solution is a sodium hydroxide solution with a mass fraction of 35 to 45%.

[0035] In some preferred embodiments, the cigarette filter fibers have a length of 0.5 to 1 cm and a diameter of 1 to 5 μm.

[0036] The chromium-containing wastewater adsorption material prepared by the present invention can deposit the fibers into a uniform membrane material by simple filtration. By controlling the mass of the composite fibers per unit area, membrane materials with different thicknesses, porosities and mechanical properties can be obtained. Preferably, the mass of the composite fibers per unit area is 0.1 g / cm 2 .

[0037] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0038] Specific embodiments of the chromium-containing wastewater adsorbent material and its preparation method of the present invention are as follows:

[0039] Example 1

[0040] The preparation method of the chromium-containing wastewater adsorption material of the embodiment specifically comprises the following steps:

[0041] (1) Preparation of cellulose acetate fibers

[0042] The tobacco and the outer paper of the discarded cigarette butt are removed, and the filter fiber part is reserved. The filter fiber is cut into a fiber bundle with a length of 0.5-1 cm and a diameter of 1-5 μm, and is mechanically separated by using a ball mill. 1 g of the filter fiber is dispersed in 200 mL of deionized water, and is ultrasonically dispersed for 3 h by using an ultrasonic crusher. The dispersed fiber is washed and then dispersed in a 40% NaOH aqueous solution at 50°C for 12 h to remove impurities such as oil and grease. The fiber is washed with deionized water and ethanol three times in sequence, and then is subjected to solvent exchange with t-butanol (solvent exchange with t-butanol can maintain the stable structure of the fiber). The fiber is freeze-dried at-78°C for 24 h to obtain cellulose acetate (CA).

[0043] (2) Preparation of the chromium-containing wastewater adsorption material

[0044] 0.1 g of the cellulose acetate fiber prepared in step (1) is dispersed in a three-necked flask containing 100 mL of a m-phenylenediamine solution with a concentration of 1 mg / mL. Immediately (here, immediately means that the Schiff base reaction time between the cellulose acetate fiber and the m-phenylenediamine is approximately 0), 25 mL of an (NH4)2S2O8 solution with a concentration of 8.44 mg / mL (the molar ratio of ammonium persulfate to m-phenylenediamine is 1:1) is added to the three-necked flask at a speed of 0.5 mL / s. While the ammonium persulfate solution is being added, the pH value of the material in the three-necked flask is adjusted to 4-7 by using a 2 mol / L NaOH solution. After the ammonium persulfate solution is added, the material in the three-necked flask is heated to 30°C, and the reaction is continuously stirred at a constant temperature for 5 h. During the heating and stirring reaction, the pH value of the material in the three-necked flask is adjusted to 4-7 by adding a 2 mol / L NaOH solution. After the reaction is completed, the material in the three-necked flask is filtered and separated by using a 120-mesh screen, and the obtained solid is repeatedly washed by ultrasonic waves until the filtrate is colorless. The solid is then washed with ammonia water (the mass fraction of the ammonia water is 25%-28%) and anhydrous ethanol three times in sequence (the ammonia water is used to neutralize the sulfuric acid produced in the reaction, and the ethanol is used to remove oligomers). The washed solid is then washed with t-butanol to replace the solvent adsorbed by the solid. Finally, the washed solid is freeze-dried at-26°C for 12 h to obtain cellulose acetate@poly-m-phenylenediamine composite fibers, which are the chromium-containing wastewater adsorption material.

[0045] Example 2

[0046] The preparation method of the chromium-containing wastewater adsorption material of the embodiment specifically comprises the following steps:

[0047] (1) Preparation of cellulose acetate fiber

[0048] The tobacco and wrapping paper of discarded cigarette butts were removed, retaining the filter fiber portion. The filter fibers were sheared into fiber bundles with a length of 0.5-1 cm and a diameter of 1-5 μm and mechanically separated using a ball mill. One gram of filter fiber was dispersed in 200 mL of deionized water and ultrasonically dispersed for 3 hours using an ultrasonic disruptor. The dispersed fibers were washed and then further dispersed in a 40% sodium hydroxide solution at 50°C for 12 hours. The fibers were then washed three times with deionized water and then ethanol, respectively. After solvent exchange with tert-butyl alcohol, they were freeze-dried at -78°C for 24 hours to obtain cellulose acetate fibers (CA).

[0049] (2) Preparation of chromium-containing wastewater adsorption materials

[0050] 0.1 g of the cellulose acetate fiber prepared in step (1) was dispersed in a three-necked flask containing 100 mL of a 1 mg / mL m-phenylenediamine solution, and the mixture was stirred at 600 rpm at 50° C. for 0.5 h in a N2 atmosphere. After the reaction was completed, 25 mL of a 8.44 mg / mL (NH4)2S2O8 solution (the molar ratio of ammonium persulfate to m-phenylenediamine was 1:1) was added dropwise to the three-necked flask at a rate of 0.5 mL / s. While adding the ammonium persulfate solution, the pH value of the material in the three-necked flask was adjusted to 4-7 with a 2 mol / L NaOH solution. After the addition of the ammonium persulfate solution was completed, the material in the three-necked flask was heated to 30° C. and the reaction was continued by stirring at a constant temperature. The reaction mixture was stirred for 5 hours, and 2 mol / L NaOH solution was added dropwise during the reaction to adjust the pH value of the material in the three-necked flask to 4-7. After the reaction, the material in the three-necked flask was filtered and separated with a 120-mesh sieve, and the filtered solid was repeatedly ultrasonically washed with deionized water until the filtrate was colorless. The solid was then washed three times with ammonia water (the mass fraction of ammonia water was 25% to 28%) and anhydrous ethanol (ammonia water was used to neutralize the sulfuric acid produced by the reaction, and ethanol was used to remove oligomers). The washed solid was then rinsed with tert-butanol to replace the solvent adsorbed by the solid. Finally, the rinsed solid was freeze-dried at -26°C for 12 hours to obtain cellulose acetate @ poly(m-phenylenediamine) composite fiber, which is the chromium-containing wastewater adsorption material.

[0051] Example 3

[0052] The preparation method of the chromium-containing wastewater adsorbent of the present embodiment specifically comprises the following steps:

[0053] (1) Preparation of cellulose acetate fiber

[0054] The tobacco and the outer paper of the discarded cigarette are removed, and the filter fiber part is reserved. The filter fiber is cut into a fiber bundle with a length of 0.5-1 cm and a diameter of 1-5 μm, and is mechanically separated by using a ball mill. 1 g of the filter fiber is dispersed in 200 mL of deionized water, and is ultrasonically dispersed for 3 h by using an ultrasonic crusher. The dispersed fiber is washed and then dispersed in a 40% NaOH aqueous solution at 50°C for 12 h. After being washed with deionized water and ethanol for three times, respectively, the fiber is subjected to solvent exchange by using t-butyl alcohol, and is freeze-dried at -78°C for 24 h to obtain cellulose acetate (CA).

[0055] (2) Preparation of the chromium-containing wastewater adsorption material

[0056] The 0.1 g of the cellulose acetate fiber prepared in step (1) is dispersed in a three-necked flask containing 100 mL of a m-phenylenediamine solution with a concentration of 1 mg / mL, and is subjected to stirring reaction at 50°C under N2 atmosphere at a speed of 600 rpm for 1 h. After the reaction is completed, 25 mL of an (NH4)2S2O8 solution with a concentration of 8.44 mg / mL (the molar ratio of ammonium persulfate to m-phenylenediamine is 1:1) is added dropwise into the three-necked flask at a speed of 0.5 mL / s. At the same time, the pH value of the material in the three-necked flask is adjusted to 4-7 by using a 2 mol / L NaOH solution. After the dropwise addition of the ammonium persulfate solution is completed, the material in the three-necked flask is warmed to 30°C, and is subjected to constant temperature stirring reaction for 5 h. During the warming and stirring reaction, the pH value of the material in the three-necked flask is adjusted to 4-7 by dropwise adding a 2 mol / L NaOH solution. After the reaction is completed, the material in the three-necked flask is filtered and separated by using a 120 mesh screen, and the obtained solid is repeatedly washed by using deionized water under ultrasonic condition until the filtrate is colorless. Then, the solid is washed with ammonia water (the mass fraction of the ammonia water is 25%-28%) and anhydrous ethanol for three times, respectively (the ammonia water is used for neutralizing the sulfuric acid generated in the reaction, and the ethanol is used for removing the oligomers). Then, the washed solid is washed with t-butyl alcohol to replace the solvent adsorbed by the solid. Finally, the washed solid is freeze-dried at -26°C for 12 h to obtain cellulose acetate-poly-m-phenylenediamine composite fiber, which is the chromium-containing wastewater adsorption material.

[0057] Example 4

[0058] The preparation method of the chromium-containing wastewater adsorption material of the present example specifically includes the following steps.

[0059] (1) Preparation of cellulose acetate fiber

[0060] The tobacco and wrapping paper of discarded cigarette butts were removed, retaining the filter fiber portion. The filter fibers were sheared into fiber bundles with a length of 0.5-1 cm and a diameter of 1-5 μm and mechanically separated using a ball mill. One gram of filter fiber was dispersed in 200 mL of deionized water and ultrasonically dispersed for 3 hours using an ultrasonic disruptor. The dispersed fibers were washed and then further dispersed in a 40% sodium hydroxide solution at 50°C for 12 hours. The fibers were then washed three times with deionized water and then ethanol, respectively. After solvent exchange with tert-butyl alcohol, they were freeze-dried at -78°C for 24 hours to obtain cellulose acetate fibers (CA).

[0061] (2) Preparation of chromium-containing wastewater adsorption materials

[0062] 0.1 g of the cellulose acetate fiber prepared in step (1) was dispersed in a three-necked flask containing 100 mL of a 1 mg / mL m-phenylenediamine solution, and the mixture was stirred at 600 rpm at 50° C. for 2 h in a N2 atmosphere. After the reaction was completed, 25 mL of a 8.44 mg / mL (NH4)2S2O8 solution (the molar ratio of ammonium persulfate to m-phenylenediamine was 1:1) was added dropwise to the three-necked flask at a rate of 0.5 mL / s. While adding the ammonium persulfate solution, the pH value of the material in the three-necked flask was adjusted to 4-7 with a 2 mol / L NaOH solution. After the addition of the ammonium persulfate solution, the material in the three-necked flask was heated to 30° C. and the reaction was continued under constant temperature stirring. 5h, during the heating and stirring reaction process, 2mol / L NaOH solution was added dropwise to adjust the pH value of the material in the three-necked flask to 4-7. After the reaction, the material in the three-necked flask was filtered and separated with a 120-mesh sieve, and the filtered solid was repeatedly ultrasonically washed with deionized water until the filtrate was colorless, and then washed three times with ammonia water (the mass fraction of ammonia water was 25%-28%) and anhydrous ethanol (ammonia water was used to neutralize the sulfuric acid produced by the reaction, and ethanol was used to remove oligomers). The washed solid was then rinsed with tert-butanol to replace the solvent adsorbed by the solid. Finally, the rinsed solid was freeze-dried at -26°C for 12h to obtain cellulose acetate @ poly(m-phenylenediamine) composite fiber, which is the chromium-containing wastewater adsorption material.

[0063] The preparation method of the chromium-containing wastewater adsorbent of Examples 5-9 specifically comprises the following steps:

[0064] (1) Preparation of cellulose acetate fiber

[0065] The tobacco and the outer paper of the discarded cigarette are removed, and the filter fiber part is reserved. The filter fiber is cut into a fiber bundle with a length of 0.5-1 cm and a diameter of 1-5 μm, and is mechanically separated by using a ball mill. 1 g of the filter fiber is dispersed in 200 mL of deionized water, and is ultrasonically dispersed for 3 h by using an ultrasonic crusher. The dispersed fiber is washed and then dispersed in a 40% NaOH aqueous solution at 50°C for 12 h. The fiber is washed with deionized water and ethanol for three times, respectively, and then is subjected to solvent exchange with t-butyl alcohol. Finally, the fiber is freeze-dried at -78°C for 24 h to obtain cellulose acetate (CA).

[0066] (2) Preparation of the chromium-containing wastewater adsorption material

[0067] The 0.1 g of the cellulose acetate fiber prepared in step (1) is dispersed in a three-necked flask containing 100 mL of the m-phenylenediamine solution, and is subjected to stirring reaction at 50°C and 600 rpm for 3 h in a N2 atmosphere. After the reaction, 25 mL of an (NH4)2S2O8 solution with a concentration of 8.44 mg / mL (the molar ratio of ammonium persulfate to m-phenylenediamine is 1:1) is added dropwise to the three-necked flask at a rate of 0.5 mL / s. The pH value of the material in the three-necked flask is adjusted to 4-7 by using a 2 mol / L NaOH solution while the ammonium persulfate solution is being added dropwise. After the addition of the ammonium persulfate solution is completed, the material in the three-necked flask is heated to 30°C, and is subjected to constant-temperature stirring reaction for 5 h. The pH value of the material in the three-necked flask is adjusted to 4-7 by using a 2 mol / L NaOH solution during the heating and stirring reaction. After the reaction is completed, the material in the three-necked flask is filtered and separated by using a 120-mesh screen, and the obtained solid is repeatedly washed by using deionized water under ultrasonic condition until the filtrate is colorless. The solid is washed with ammonia water (the mass fraction of the ammonia water is 25%-28%) and anhydrous ethanol for three times, respectively (the ammonia water is used to neutralize the sulfuric acid generated in the reaction, and the ethanol is used to remove the oligomers). The washed solid is washed with t-butyl alcohol to replace the solvent adsorbed by the solid. Finally, the washed solid is freeze-dried at -26°C for 12 h to obtain cellulose acetate@poly-m-phenylenediamine composite fiber, which is the chromium-containing wastewater adsorption material.

[0068] In the preparation method of the chromium-containing wastewater adsorption material in examples 5-9, the mass fraction of the m-phenylenediamine solution is 1 mg / mL, 5 mg / mL, 10 mg / mL, 20 mg / mL and 50 mg / mL, respectively.

[0069] In other examples, the molar ratio of ammonium persulfate to m-phenylenediamine is 1:3, or ammonium persulfate is replaced by potassium persulfate, sodium persulfate, hydrogen peroxide or ferric trichloride.

[0070] Example 10

[0071] The preparation method of the chromium-containing wastewater adsorption material of the embodiment specifically comprises the following steps:

[0072] (1) Preparation of cellulose acetate fibers

[0073] The tobacco and the outer paper of the discarded cigarette butt are removed, and the filter fiber part is reserved. The filter fiber is cut into a fiber bundle with a length of 0.5-1 cm and a diameter of 1-5 μm, and is mechanically separated by using a ball mill. 1 g of the filter fiber is dispersed in 200 mL of deionized water, and is ultrasonically dispersed for 3 h by using an ultrasonic crusher. The dispersed fiber is washed and then dispersed in a 40% NaOH aqueous solution at 50°C for 12 h. After being washed with deionized water and ethanol for three times, respectively, the fiber is subjected to solvent exchange by using t-butanol, and is freeze-dried at -78°C for 24 h to obtain cellulose acetate (CA).

[0074] (2) Preparation of the chromium-containing wastewater adsorption material

[0075] 0.1 g of the cellulose acetate fiber prepared in step (1) is dispersed in a three-necked flask containing 100 mL of a m-phenylenediamine solution with a concentration of 1 mg / mL, and is subjected to stirring reaction at 50°C under N2 atmosphere at a speed of 600 rpm for 3 h. The pH value of the reaction system is measured by using a pH meter during the stirring reaction. After the reaction is completed, 25 mL of a K2S2O8 solution with a concentration of 10 mg / mL (the molar ratio of potassium persulfate to m-phenylenediamine is 1:1) is added dropwise into the three-necked flask at a speed of 0.5 mL / s. The pH value of the material in the three-necked flask is adjusted to 4-7 by using a 2 mol / L NaOH solution while the potassium persulfate solution is being added dropwise. After the dropwise addition is completed, the material in the three-necked flask is heated to 30°C, and is subjected to constant-temperature stirring reaction for 5 h. After the reaction is completed, the material in the three-necked flask is filtered and separated by using a 120-mesh screen, and the obtained solid is repeatedly washed by using deionized water under ultrasonic condition until the filtrate is colorless. The solid is washed with ammonia water (the mass fraction of the ammonia water is 25%-28%) and anhydrous ethanol for three times, respectively (the ammonia water is used for neutralizing the sulfuric acid generated in the reaction, and the ethanol is used for removing the oligomers). The washed solid is washed by using t-butanol to replace the solvent adsorbed by the solid. Finally, the washed solid is freeze-dried at -26°C for 12 h to obtain cellulose acetate@poly-m-phenylenediamine composite fibers, which are the chromium-containing wastewater adsorption material.

[0076] Example 11

[0077] The preparation method of the chromium-containing wastewater adsorption material of the embodiment specifically comprises the following steps:

[0078] (1) Preparation of cellulose acetate fibers

[0079] The tobacco and the outer paper of the discarded cigarette are removed, and the filter fiber part is reserved. The filter fiber is cut into a fiber bundle with a length of 0.5-1 cm and a diameter of 1-5 μm, and is mechanically separated by using a ball mill. 1 g of the filter fiber is dispersed in 200 mL of deionized water, and is ultrasonically dispersed for 3 h by using an ultrasonic crusher. The dispersed fiber is washed and then dispersed in a 40% NaOH aqueous solution at 50°C for 12 h. After being washed with deionized water and ethanol for three times, respectively, the fiber is subjected to solvent exchange by using t-butyl alcohol, and is freeze-dried at -78°C for 24 h to obtain cellulose acetate (CA).

[0080] (2) Preparation of the chromium-containing wastewater adsorption material

[0081] The 0.1 g of the cellulose acetate fiber prepared in step (1) is dispersed in a three-necked flask containing 100 mL of a m-phenylenediamine solution with a concentration of 1 mg / mL, and is subjected to stirring reaction at 50°C under N2 atmosphere at a speed of 600 rpm for 3 h. The pH value of the reaction system is measured by using a pH meter during the stirring reaction. After the reaction is completed, a certain amount of H2O2 solution with a concentration of about 0.004 mol / L is added dropwise into the three-necked flask at a speed of 0.5 mL / s (the H2O2 solution is prepared before the experiment, and the concentration is determined by using the potassium permanganate titration method, and the amount is controlled to ensure that the molar ratio of the m-phenylenediamine to the H2O2 is 1:1). Then, 25 mL of FeSO4 solution with a concentration of 4×10 -4 mol / L and 10 mL of sulfuric acid solution with a concentration of 1.0 mol / L are continuously added dropwise. After the addition is completed, the material in the three-necked flask is heated to 30°C, and is subjected to constant temperature stirring reaction for 5 h. After the reaction is completed, the material in the three-necked flask is filtered and separated by using a 120-mesh screen, and the obtained solid is repeatedly washed by using deionized water under ultrasonic condition until the filtrate is colorless. Then, the solid is washed with ammonia water (the mass fraction of the ammonia water is 25%-28%) and anhydrous ethanol for three times, respectively (the ammonia water is used to neutralize the sulfuric acid generated in the reaction, and the ethanol is used to remove the oligomers). The washed solid is washed with t-butyl alcohol to replace the solvent adsorbed by the solid. Finally, the washed solid is freeze-dried at -26°C for 12 h to obtain cellulose acetate@poly-m-phenylenediamine composite fiber, i.e., the chromium-containing wastewater adsorption material.

[0082] Example 12

[0083] The preparation method of the chromium-containing wastewater adsorption material of the present example specifically includes the following steps.

[0084] (1) Preparation of cellulose acetate fiber

[0085] The tobacco and the outer paper of the discarded cigarette are removed, and the filter fiber part is reserved. The filter fiber is cut into a fiber bundle with a length of 0.5-1 cm and a diameter of 1-5 μm, and is mechanically separated by using a ball mill. 1 g of the filter fiber is dispersed in 200 mL of deionized water, and is ultrasonically dispersed for 3 h by using an ultrasonic crusher. The dispersed fiber is washed and then dispersed in a 40% NaOH aqueous solution at 50°C for 12 h. After being washed with deionized water and ethanol respectively for three times, the fiber is subjected to solvent exchange by using t-butyl alcohol, and is freeze-dried at -78°C for 24 h to obtain cellulose acetate fiber (CA).

[0086] (2) Preparation of the chromium-containing wastewater adsorption material

[0087] The cellulose acetate fiber prepared in step (1) is dispersed in a three-necked flask containing 100 mL of a m-phenylenediamine solution with a concentration of 1 mg / mL. The stirring reaction is carried out at 50°C under N2 atmosphere at a speed of 600 rpm for 3 h. The pH value of the reaction system is measured by using a pH meter during the stirring reaction. After the reaction is completed, a certain amount of FeCl3 solution with a concentration of about 0.004 mol / L is added dropwise into the three-necked flask at a speed of 0.5 mL / s (the FeCl3 solution is prepared before the experiment, and the concentration is determined by using o-diazenephthalene-spectrophotometer. The molar ratio of m-phenylenediamine to FeCl3 is ensured to be 1:1 by controlling the volume). After the dropwise addition is completed, the material in the three-necked flask is heated to 30°C, and the constant-temperature stirring reaction is continued for 5 h. After the reaction is completed, the material in the three-necked flask is separated by using a 120-mesh screen, and the obtained solid is repeatedly washed by using deionized water under ultrasonic condition until the filtrate is colorless. Then, the solid is washed with ammonia water (the mass fraction of the ammonia water is 25%-28%) and anhydrous ethanol respectively for three times (the ammonia water is used to neutralize the sulfuric acid produced in the reaction, and the ethanol is used to remove the oligomers). Then, the washed solid is washed with t-butyl alcohol to replace the solvent adsorbed by the solid. Finally, the washed solid is freeze-dried at -26°C for 12 h to obtain cellulose acetate@poly-m-phenylenediamine composite fiber, i.e. the chromium-containing wastewater adsorption material.

[0088] Experimental Example 1

[0089] This experiment is used to analyze the mass percentage of the poly-m-phenylenediamine nanoparticles in the chromium-containing wastewater adsorption material. The calculation formula of the mass percentage of the poly-m-phenylenediamine nanoparticles in the chromium-containing wastewater adsorption material is as follows:

[0090]

[0091] wherein, w 产物 is the mass of the chromium-containing wastewater adsorption material, and the unit is g, w CA is the mass of the cellulose acetate fiber, and the unit is g.

[0092] The results show that the mass percentage of poly-m-phenylenediamine nanoparticles in the chromium-containing wastewater adsorption materials prepared in Examples 1-9 is 1.96%, 11.11%, 17.23%, 21.26%, 21.88%, 59.18%, 73.16%, 77.19% and 74.25%, respectively. This result shows that the amount of poly-m-phenylenediamine nanoparticles attached to the surface of the cellulose acetate fibers increases with the increase of the adsorption reaction time of m-phenylenediamine monomers. Examples 5-9 show that the amount of poly-m-phenylenediamine nanoparticles attached to the surface of the cellulose acetate fibers increases with the decrease of the mass ratio of cellulose acetate fibers to m-phenylenediamine monomers, but when the mass ratio exceeds 1:20, the mass percentage of poly-m-phenylenediamine nanoparticles in the adsorption material tends to be stable. This shows that the loading amount of m-phenylenediamine in the in-situ polymerization reaction depends on the total amount of m-phenylenediamine monomers adsorbed by the fibers, and when the fibers adsorb m-phenylenediamine monomers to saturation, increasing the concentration of m-phenylenediamine monomers cannot increase the loading amount.

[0093] Experimental Example 2

[0094] In this experimental example, the appearance and morphology of the chromium-containing wastewater adsorption materials prepared in Examples 1-9 were analyzed. The chromium-containing wastewater adsorption materials prepared in Examples 1-9 were analyzed by scanning electron microscopy (SEM), and the results are shown in Figure 1 Figure 1 a-1i are scanning electron microscope images of the chromium-containing wastewater adsorption materials prepared in Examples 1-9. In addition, the appearance of the chromium-containing wastewater adsorption material prepared in Example 8 was analyzed and characterized by transmission electron microscopy (TEM), and the results are shown in Figure 2 Figure 2 a is a picture of poly-m-phenylenediamine nanoparticles attached to the surface of the fibers, Figure 2 b is a picture of poly-m-phenylenediamine nanoparticles grown inside the fiber bundle, Figure 2 c and 2d are pictures of the interface between cellulose acetate fibers and poly-m-phenylenediamine nanoparticles at different resolutions.

[0095] As can be seen from Figure 1 , after in-situ polymerization of polyaniline on cellulose acetate fibers, poly-m-phenylenediamine nanoparticles with a diameter of tens to hundreds of nanometers are observed on the cellulose acetate fibers Figure 1 (a-1i). With the increase of the adsorption reaction time of m-phenylenediamine monomers, the poly-m-phenylenediamine nanoparticles are more uniformly attached to the surface of the cellulose acetate fibers. When the mass ratio of cellulose acetate fibers to m-phenylenediamine monomers decreases from 1:1 to 1:5, the diameter of the poly-m-phenylenediamine nanoparticles increases significantly (about 3 times). In addition, with the increase of the ratio of cellulose acetate fibers to m-phenylenediamine monomers, the diameter of the poly-m-phenylenediamine nanoparticles tends to be uniform. However, when m-phenylenediamine monomers are added in excess, the poly-m-phenylenediamine nanoparticles agglomerate and accumulate Figure 1 ​​i)。Therefore, by changing the reaction time of m-phenylenediamine monomer with cellulose acetate fibers and the mass ratio of m-phenylenediamine monomer to cellulose acetate fibers, the diameter and number of poly-m-phenylenediamine nanoparticles loaded on cellulose acetate fibers can be controlled. The large number of carbonyl groups on cellulose acetate can undergo addition reaction with m-phenylenediamine monomer to form Schiff base structure, making the combination of poly-m-phenylenediamine and cellulose acetate fibers more stable and thus avoiding nanoparticle shedding.

[0096] From Figure 2 It can be seen that the poly-m-phenylenediamine nanospheres are formed by in-situ polymerization on cellulose acetate fibers and can be combined into cellulose acetate fibers in two ways, as shown in Figure 2 a and 2b. Poly-m-phenylenediamine nanoparticles grow on the surface of cellulose acetate fibers Figure 2 a) and embed into the interior of cellulose acetate fibers Figure 2 b). This phenomenon may be due to the addition of part of the -NH2- of m-phenylenediamine monomer to the C=O of cellulose acetate to form a Schiff base structure, which then enters the cellulose acetate fiber bundle, inducing the generation of poly-m-phenylenediamine nanoparticles wrapped by fiber belts, which can effectively prevent the nanoparticles from falling off the cellulose acetate fibers. Microscopic images Figure 2 c and 2d) confirm the uneven boundary fusion or combination of poly-m-phenylenediamine nanoparticles and cellulose acetate fibers, further proving the stable combination of the two.

[0097] Experimental Example 3

[0098] In this experimental example, the structure of the chromium-containing wastewater adsorption material prepared in Examples 1-9 was characterized. Cellulose acetate, poly-m-phenylenediamine, and the chromium-containing wastewater adsorption material prepared in Examples 1-6 were characterized by infrared analysis and Raman spectrum analysis, and the results are shown in Figure 3 , Figure 4 and Figure 5 . Figure 3 In the figures, 1 represents cellulose acetate, 2 represents poly-m-phenylenediamine, 3 represents the chromium-containing wastewater adsorption material prepared in Example 1, 4 represents the chromium-containing wastewater adsorption material prepared in Example 2, 5 represents the chromium-containing wastewater adsorption material prepared in Example 3, 6 represents the chromium-containing wastewater adsorption material prepared in Example 4, 7 represents the chromium-containing wastewater adsorption material prepared in Example 5, and 8 represents the chromium-containing wastewater adsorption material prepared in Example 6. Figure 4 In the figures, 1 represents the chromium-containing wastewater adsorption material prepared in Example 1, 2 represents the chromium-containing wastewater adsorption material prepared in Example 2, 3 represents the chromium-containing wastewater adsorption material prepared in Example 3, 4 represents the chromium-containing wastewater adsorption material prepared in Example 4, and 5 represents the chromium-containing wastewater adsorption material prepared in Example 5. Figure 5 a-5i are Raman spectrum area scans of the chromium-containing wastewater adsorption materials prepared in Examples 1-9, respectively.

[0099] From Figure 3 It is known that cellulose acetate fiber exhibits several infrared absorption peaks, which are -OH stretching vibration (3200-3500 cm -1 ), -CH2- stretching vibration (2893 cm -1 ) and C-O-C asymmetric stretching vibration (1159 cm -1 ), respectively. For poly-m-phenylenediamine, the main absorption peaks are -NH- at 3500-3000 cm -1 , quinonimine at 1625 cm -1 , aniline structure at 1500 cm -1 , and C-N at 1257 cm -1 , respectively. Similar characteristic peaks of poly-m-phenylenediamine are observed in the cellulose acetate / poly-m-phenylenediamine composite fiber sample, indicating that poly-m-phenylenediamine is complexed with cellulose acetate fiber. With the increase of adsorption reaction time, the intensity of -NH-, quinonimine and aniline relatively increases due to more poly-m-phenylenediamine formed. In addition, the relative intensity of the characteristic peaks of poly-m-phenylenediamine in the product increases when the mass ratio of cellulose acetate to m-phenylenediamine monomer decreases from 1:1 to 1:5. It is worth noting that the C-N absorption peak of poly-m-phenylenediamine after complexation shifts from 1257 cm -1 to 1281 cm -1 , and the intensity increases. This is due to the formation of Schiff base structure by the addition reaction of -NH2 of m-phenylenediamine monomer and C=O on the molecular chain of cellulose acetate, which confirms the strong interaction between cellulose acetate fiber and poly-m-phenylenediamine nanoparticles.

[0100] From Figure 4 It is known that for cellulose acetate, the peak at 1095 cm -1 is the asymmetric stretching vibration of C-O-C in the glycosidic ring and polysaccharide. The strong peak at 2900 cm -1 is the symmetric C-H stretching vibration. For poly-m-phenylenediamine, the two strong peaks at 1573 cm -1 and 1352 cm -1 belong to the characteristic absorption bands of aniline and quinonimine, respectively. In order to study the relative distribution of poly-m-phenylenediamine nanoparticles in the cellulose acetate fiber matrix, and considering that the peak intensity at 1573 cm -1 is higher, the Raman mapping is carried out according to this peak position (as shown in Figure 5 ). Red indicates relatively high density of poly-m-phenylenediamine nanoparticles. The results show that poly-m-phenylenediamine nanoparticles can be uniformly distributed on the fiber only when m-phenylenediamine monomer is fully reacted with cellulose acetate.

[0101] Experimental Example 4

[0102] In this experimental example, the chromium-containing wastewater adsorbents prepared in Examples 1-9 were used to treat chromium-containing wastewater. The chromium-containing wastewater adsorbents prepared in Examples 1-9 were named CA@PmPD(1:1)0, CA@PmPD(1:1) 0.5 , CA@PmPD(1:1)1, CA@PmPD(1:1)2, CA@PmPD(1:1)3, CA@PmPD(1:5)3, CA@PmPD(1:10)3, CA@PmPD(1:20)3, CA@PmPD(1:50)3.

[0103] ① Constant temperature adsorption experiment

[0104] 25 mg of chromium-containing wastewater adsorption material was added to 50 mL of K2Cr2O7 solution with an initial concentration of 100-500 mg / L and pH = 2, and the solution was shaken at a speed of 150 rpm at 30°C for 4 hours (at this time, the chromium-containing wastewater adsorption material reached saturation in the adsorption of chromium ions). The solution was then filtered with a filter membrane with a pore size of 0.45 μm, and the filtrate was collected. The concentration of Cr(VI) in the filtrate was determined by diphenylcarbazide-spectrophotometry at a wavelength of 540 nm.

[0105] After the experiment, the adsorption amount was calculated according to the following formula:

[0106]

[0107] Where C0 is the initial concentration of the solution, m is the mass of the adsorbent added, V is the volume of the solution, q e is the saturated adsorption capacity of the adsorbent, C e is the concentration of the solution when adsorption reaches saturation.

[0108] The saturated adsorption capacity of Cr(VI) in K2Cr2O7 solutions with different concentrations by different chromium-containing wastewater adsorption materials is as follows: Figure 6 And as shown in Table 1. Among them, Figure 6 a is a schematic diagram showing the adsorption capacity of chromium ions in K2Cr2O7 solutions of different concentrations by the chromium-containing wastewater adsorbent prepared in Examples 1-5. Figure 6 b is a schematic diagram showing the adsorption of chromium ions in K2Cr2O7 solutions of different concentrations by the chromium-containing wastewater adsorbent prepared in Examples 5-9. The Langmuir adsorption isotherm model was used to fit the experimental data. Langmuir is a classic single-layer adsorption isotherm model, and its mathematical expression is as follows:

[0109]

[0110] Among them, C e is the equilibrium solution concentration (mg / L), q eq is the adsorption capacity of the adsorbent (mg / g) at equilibrium time t, C0 is the initial concentration of the solution, C is the concentration of the solution at equilibrium time t, m is the mass of the adsorbent, and V is the volume of the solution. m q is the maximum adsorption capacity of the adsorbent (mg / g), and b is the thermodynamic constant (L / mg).

[0111] Table 1 Isothermal adsorption data of different adsorbents for Cr(Ⅵ) in wastewater containing chromium

[0112]

[0113] From Table 1 and Figure 6 It can be seen that the adsorption process of the adsorbents for Cr(Ⅵ) in wastewater containing chromium prepared in Examples 1-9 conforms to the Langmuir model, indicating that the adsorption mechanism is monolayer adsorption, and the maximum saturated adsorption capacity of the adsorbents for Cr(Ⅵ) in wastewater containing chromium prepared in Examples 1-9 can reach 434.78 mg / g.

[0114] ② Adsorption kinetics experiment

[0115] 25 mg of the adsorbent for Cr(Ⅵ) in wastewater containing chromium was added to 50 mL of a K2Cr2O7 solution with an initial concentration of 500 mg / L and pH = 2, and the solution was oscillated at 30°C and a speed of 150 rpm for 0.5-4 h. Then, the solution was filtered with a filter membrane with a pore size of 0.45 μm, the filtrate was collected, and the concentration of Cr(Ⅵ) in the filtrate was determined by the diphenylcarbazide-spectrophotometric method at a wavelength of 540 nm.

[0116] After the experiment, the adsorption capacity of the adsorbent for Cr(Ⅵ) in wastewater containing chromium prepared in Examples 1-9 was calculated according to the following formula:

[0117]

[0118] wherein q is the adsorption capacity of the adsorbent (mg / g) at equilibrium time t, C0 is the initial concentration of the solution, C is the concentration of the solution at equilibrium time t, m is the mass of the adsorbent, and V is the volume of the solution. t t wherein q is the adsorption capacity of the adsorbent (mg / g) at equilibrium time t, C0 is the initial concentration of the solution, C is the concentration of the solution at equilibrium time t, m is the mass of the adsorbent, and V is the volume of the solution.

[0119] The mathematical expression of the pseudo-first-order kinetic model is as follows:

[0120]

[0121] wherein q is the saturated adsorption capacity, q is the adsorption capacity of the adsorbent (mg / g) at equilibrium time t, and k1 is the pseudo-first-order kinetic constant. e t wherein q is the saturated adsorption capacity, q is the adsorption capacity of the adsorbent (mg / g) at equilibrium time t, and k1 is the pseudo-first-order kinetic constant.

[0122] The mathematical expression of the pseudo-second-order kinetic model is as follows:

[0123]

[0124] wherein q is the saturated adsorption capacity, q is the adsorption capacity of the adsorbent (mg / g) at equilibrium time t, and k1 is the pseudo-first-order kinetic constant. e ​​q is the saturated adsorption capacity, qe is the adsorption capacity of the adsorbent at time t (mg / g), k2 is the pseudo-second order kinetics constant. t qe is the adsorption capacity of the adsorbent at time t (mg / g), k2 is the pseudo-second order kinetics constant.

[0125] The experimental data were fitted according to the pseudo-first order kinetics model and the pseudo-second order kinetics model, and the values of the parameters in the model were obtained. The adsorption kinetics data of the adsorbents for Cr(Ⅵ) in K2Cr2O7 solution are shown in Table 2 and Figure 7

[0126] Table 2 Adsorption kinetics data of the adsorbents for Cr(Ⅵ) in K2Cr2O7 solution

[0127]

[0128] From Table 2 and Figure 7 it can be seen that the adsorbents are more suitable for the pseudo-second order kinetics model. It can be known that the chemical adsorption is the rate-controlling step in the adsorption process of Cr(Ⅵ) by the polymeric Schiff base and its reduced product. The adsorbents prepared in Examples 1-9 can reach 67% of the saturated adsorption capacity within 0.5 h, and have a high adsorption rate.

[0129] 3. Effect of solution pH on saturated adsorption capacity

[0130] 25 mg of the adsorbent prepared in Example 8 was added into 7 bottles of 50 mL K2Cr2O7 solution with an initial concentration of 500 mg / L, respectively, and the pH of the solution was adjusted to 0, 1, 2, 3, 4, 5 and 6, respectively. The solution was oscillated at 30°C at a speed of 150 rpm for 4 h. After oscillation, the solution was filtered and the filtrate was collected. The concentration of Cr(Ⅵ) in the filtrate was determined by the diphenyl carbazide-spectrophotometric method at a wavelength of 540 nm. The experimental results are shown in Figure 8 From Figure 8 it can be seen that the adsorbent prepared in Example 8 has good acid resistance and the saturated adsorption capacity is the largest at pH = 2.

[0131] Experimental Example 5

[0132] This experimental example is a recovery and regeneration test of the adsorbent. The experimental steps are as follows: 100 mg of the adsorbent prepared in Example 8 was added into 200 mL K2Cr2O7 solution with an initial concentration of 500 mg / L, and the pH of the solution was adjusted to 2. The solution was oscillated at 30°C at a speed of 150 rpm for 4 h. After oscillation, the adsorbent was recovered by vacuum filtration using a filter membrane with a diameter of 50 mm (as shown in the left side of Figure 9 After being added into water (as shown in the middle picture of Figure 9 ), the adsorbent can be dispersed in water again by stirring (as shown in the right side of Figure 9 ​The adsorbent was dispersed in 1 mol / L NaOH solution and ultrasonically desorbed for 2 h. After the regeneration of the adsorbent, the adsorbent was washed with deionized water, and then washed with tert-butyl alcohol to replace the solvent adsorbed by the solid adsorbent. Finally, the regenerated adsorbent was freeze-dried at -26℃ for 12 h and used for the second adsorption. The method was the same as that of the constant temperature adsorption experiment in Experimental Example 4. After five cycles, the adsorption capacity of Cr(VI) remained at 98%, 89%, 82%, 78% and 73% of the initial adsorption capacity, respectively, indicating that the synthesized adsorbent had good regeneration performance.

Claims

1. A method for preparing a chromium-containing wastewater adsorption material, characterized in that: The method comprises the following steps: first subjecting cellulose acetate fiber and phenylenediamine to a Schiff base reaction, and then subjecting them to an oxidative polymerization reaction under the action of an oxidant to obtain a chromium-containing wastewater adsorption material; the phenylenediamine is m-phenylenediamine; the oxidant is potassium persulfate, sodium persulfate, ammonium persulfate, hydrogen peroxide or ferric chloride; the oxidant is added in the form of a solution, and during the process of adding the oxidant and the oxidative polymerization reaction, the pH of the reaction system is controlled to be 4-7.

2. The method for preparing the chromium-containing wastewater adsorbent according to claim 1, wherein: The mass ratio of the phenylenediamine to the cellulose acetate fiber is 1:(1-50).

3. The method for preparing the chromium-containing wastewater adsorbent material according to claim 2, wherein: The mass ratio of the phenylenediamine to the cellulose acetate fiber is 1:(10-20).

4. The method for preparing the chromium-containing wastewater adsorbent according to claim 1, wherein: The reaction time of the Schiff base is 0.5 to 3 hours.

5. The method for preparing the chromium-containing wastewater adsorbent according to claim 1, wherein: The molar ratio of the phenylenediamine to the oxidant is 1:(1-3).

6. The method for preparing the chromium-containing wastewater adsorbent material according to claim 1, wherein: The cellulose acetate fiber is prepared by a method comprising the following steps: ultrasonically dispersing cigarette filter fibers and water, separating the solid and the liquid, washing, soaking the washed solid in an alkali solution to remove impurities, then washing the soaked solid, and freeze-drying to obtain the cellulose acetate fiber; the cigarette filter fiber is a fiber bundle with a length of 0.5 to 1 cm and a diameter of 1 to 5 μm.

7. A chromium-containing wastewater adsorption material prepared by the method for preparing a chromium-containing wastewater adsorption material according to any one of claims 1 to 6.

Images