Adsorptive particle electrode for wastewater treatment and preparation method thereof

Abstract

The application belongs to the technical field of wastewater treatment and specifically relates to an adsorption granular electrode for wastewater treatment and a preparation method thereof. The preparation method comprises the following steps: zinc salt, vanadium salt, scandium salt and cetyltrimethylammonium bromide are added into water and stirred, and after pH is adjusted at 70-80 DEG C, the stirring is continued, and then the modified mesoporous zinc oxide is obtained through filtration, drying and calcination; the modified mesoporous zinc oxide is dispersed in water, and then composite aerogel is added for soaking, and the adsorption granular electrode is obtained through filtration, washing, drying and grinding. The adsorption granular electrode prepared by the application can be used for degradation of printing and dyeing wastewater, and has excellent performances such as high degradation rate, fast degradation rate and reusability.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wastewater treatment, and particularly relates to an adsorption granular electrode for wastewater and waste liquid treatment and a preparation method thereof. BACKGROUND

[0002] Under the background of rapid industrialization and urbanization, the output of urban domestic wastewater and industrial wastewater continues to rise. Among them, printing and dyeing wastewater becomes a problem in wastewater treatment because it contains complex and difficult-to-degrade pollutants such as dyes and auxiliaries. If the printing and dyeing wastewater is directly discharged without effective treatment or incomplete treatment, it will cause serious damage to the water ecology and trigger a water resource crisis. At present, conventional water treatment technologies mainly include physical, chemical and biological methods. The physical method has limited effect on the removal of dissolved pollutants in printing and dyeing wastewater; the chemical method can degrade part of the pollutants, but may cause secondary pollution and has high cost; the biological method has low treatment efficiency for difficult-to-degrade printing and dyeing wastewater due to the influence of wastewater biodegradability. Overall, the conventional technologies have problems such as poor removal effect or high cost in the treatment of printing and dyeing wastewater.

[0003] Electrochemical catalysis technology is an emerging wastewater and waste liquid treatment technology, which has the advantages of convenient operation, high cost-effectiveness and environmental friendliness. With the development of technology, on the basis of traditional two-dimensional electrode reactors, three-dimensional electrode reactors are formed by filling granular electrodes, a large number of micro-electrodes are formed under the action of an electric field, the electrolytic cell area ratio and electrocatalytic active sites of the reactor are increased, the migration distance of the reactants is shortened, the mass transfer rate is increased, and the current efficiency and treatment effect can be effectively improved. The commonly used granular electrodes mainly include activated carbon, metal and its oxide particles, etc. These materials have the disadvantages of low conductivity, low electrochemical oxidation efficiency, poor acid and alkali resistance, etc., which easily leads to problems such as low current efficiency, insufficient stability and performance decline of the electrode reactor, so these materials need to be compounded or modified to make the materials have higher electrocatalytic performance and chemical stability, and better apply to the field of wastewater and waste liquid treatment. SUMMARY

[0004] The first object of the present application is to provide a preparation method of an adsorption granular electrode for wastewater and waste liquid treatment.

[0005] The second object of the present application is to provide an adsorption granular electrode for wastewater and waste liquid treatment, which has high wastewater degradation rate, fast reaction rate and stable repeated use performance.

[0006] In order to achieve the above objects, the technical scheme adopted by the present application is as follows:

[0007] A preparation method of an adsorption granular electrode for wastewater and waste liquid treatment, comprising the following steps:

[0008] (1) zinc salt, vanadium salt, scandium salt and cetyltrimethylammonium bromide are added into water and stirred, and after pH is adjusted at 70-80 DEG C, the stirring is continued, and then the modified mesoporous zinc oxide is obtained after filtration, drying and calcination;

[0009] (2) the modified mesoporous zinc oxide is dispersed in water to obtain a dispersion liquid, and the composite aerogel is soaked in the dispersion liquid for 20-30h, and then the adsorption particle electrode is obtained after filtration, washing, drying and grinding.

[0010] Further, in step (1), the molar ratio of the zinc salt, vanadium salt, scandium salt and cetyltrimethylammonium bromide is 1:(0.05-0.15):(0.05-0.1):(0.3-0.5).

[0011] Further, in step (1), the pH value is adjusted to 7.5-8.5, and the stirring is continued for 1-3h.

[0012] Further, in step (1), the calcination is carried out at a temperature of 500-700 DEG C for 3-5h.

[0013] Further, in step (2), the composite aerogel is prepared by the following process:

[0014] (a) nickel salt, iron salt and urea are added into water, and after pH is adjusted to 9-12, a hydrothermal reaction is carried out, and then nickel-iron hydrotalcite is obtained after filtration and drying;

[0015] (b) the nickel-iron hydrotalcite and cerium sulfide are dispersed in N-methylpyrrolidone, and after poly-pyrrole is added and stirred, the composite aerogel is obtained after freeze-drying.

[0016] Further, in step (a), the molar ratio of the nickel salt, iron salt and urea is 1:(3-4):(12-24), and the hydrothermal reaction is carried out at a temperature of 130-160 DEG C for 8-12h.

[0017] Further, in step (b), the mass ratio of the nickel-iron hydrotalcite, cerium sulfide and poly-pyrrole is 10:0.5-1.5:1-2, and the stirring is carried out for 1-5h.

[0018] Further, in step (2), the mass ratio of the modified mesoporous zinc oxide and the composite aerogel is 1:8-10.

[0019] An adsorption particle electrode for wastewater treatment is prepared by the above method.

[0020] The beneficial technical effects of the present application are as follows:

[0021] 1.The present application is to load scandium vanadium bimetallic doped mesoporous zinc oxide in the particle electrode, which can produce hydroxyl radicals by electrocatalysis, and can also generate electron-hole pairs under the catalysis of light to form superoxide radicals and hydroxyl radicals, respectively, which can decompose pollutants in water into CO2 and H2O; and the mesoporous structure has a large specific surface area, which can provide abundant active sites and enhance the adsorption capacity of pollutants, realizing the adsorption and photoelectric synergistic catalytic treatment of wastewater. However, the light response range of zinc oxide is narrow, and it is easy to cause photo corrosion in the cycle process, the present application uses scandium vanadium co-doping to modify it, which can control the energy band structure of zinc oxide, expand its light response range and improve the degradation rate.

[0022] 2.The present application uses nickel-iron hydrotalcite and cerium sulfide composite aerogel as a carrier, nickel-iron hydrotalcite has a two-dimensional layered structure and abundant active sites, which can adsorb pollutants in water through interlayer anion exchange, and catalytically degrade through the oxidation and reduction of nickel and iron ions; cerium sulfide has good conductivity and redox properties, and can improve the electron transport rate and catalytic activity when combined with nickel-iron hydrotalcite, and can form sulfur vacancies to inhibit the attachment and growth of microorganisms, and maintain the long-term stability of the particle electrode; the aerogel has a stable porous network structure, which not only provides an adsorption channel, but also ensures the cycle stability of the particle electrode. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 SEM image of the adsorption particle electrode prepared in Example 1 of the present application;

[0024] Figure 2 Performance comparison chart of the adsorption particle electrodes prepared in Examples 1-3 and Comparative Examples 1-3 for degrading rhodamine B. DETAILED DESCRIPTION

[0025] The following is a further detailed description of the present application in conjunction with specific preferred embodiments, which cannot be considered as limiting the specific implementation of the present application to these descriptions. For ordinary skilled persons in the technical field to which the present application belongs, without departing from the concept of the present application, a number of simple deductions or substitutions can be made, which should be considered as belonging to the protection scope of the present application. The specific conditions not mentioned in the examples are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used, such as those not specifically mentioned, are conventional products obtained through market channels.

[0026] (I) Preparation Example

[0027] Preparation Example 1

[0028] Preparation Example 1 provides a composite aerogel, which is prepared by the following preparation process:

[0029] (a) according to the amount ratio of nickel nitrate, iron nitrate, urea and water 1 mmol: 3 mmol: 18 mmol: 45 mL, the nickel nitrate, iron nitrate and urea are ultrasonically dispersed in water, 18wt% ammonia water is used to adjust the pH to 10, then hydrothermal reaction is carried out at 140℃ for 10h, after filtration and drying, the nickel-iron hydrotalcite is obtained;

[0030] (b) according to the amount ratio of nickel-iron hydrotalcite, cerium sulfide, polypyrrole and N-methyl pyrrolidone 10mg: 1mg: 1mg: 50mL, the nickel-iron hydrotalcite and cerium sulfide are ultrasonically dispersed in N-methyl pyrrolidone, the polypyrrole is added and uniformly mixed, stirring reaction is carried out for 3h, after freeze-drying, the composite aerogel is obtained.

[0031] Preparation Example 2

[0032] Preparation Example 2 provides a composite aerogel, which is prepared by the following preparation process:

[0033] (a) according to the amount ratio of nickel nitrate, iron nitrate, urea and water 1 mmol: 3 mmol: 12 mmol: 40 mL, the nickel nitrate, iron nitrate and urea are ultrasonically dispersed in water, 15wt% ammonia water is used to adjust the pH to 9, then hydrothermal reaction is carried out at 130℃ for 8h, after filtration and drying, the nickel-iron hydrotalcite is obtained;

[0034] (b) according to the amount ratio of nickel-iron hydrotalcite, cerium sulfide, polypyrrole and N-methyl pyrrolidone 10mg: 0.5mg: 1mg: 40mL, the nickel-iron hydrotalcite and cerium sulfide are ultrasonically dispersed in N-methyl pyrrolidone, the polypyrrole is added and uniformly mixed, stirring reaction is carried out for 1h, after freeze-drying, the composite aerogel is obtained.

[0035] Preparation Example 3

[0036] Preparation Example 3 provides a composite aerogel, which is prepared by the following preparation process:

[0037] (a) according to the amount ratio of nickel nitrate, iron nitrate, urea and water 1 mmol: 4 mmol: 24 mmol: 50 mL, the nickel nitrate, iron nitrate and urea are ultrasonically dispersed in water, 20wt% ammonia water is used to adjust the pH to 12, then hydrothermal reaction is carried out at 160℃ for 12h, after filtration and drying, the nickel-iron hydrotalcite is obtained;

[0038] (b) according to the amount ratio of nickel-iron hydrotalcite, cerium sulfide, polypyrrole and N-methyl pyrrolidone 10mg: 1.5mg: 2mg: 60mL, the nickel-iron hydrotalcite and cerium sulfide are ultrasonically dispersed in N-methyl pyrrolidone, the polypyrrole is added and uniformly mixed, stirring reaction is carried out for 5h, after freeze-drying, the composite aerogel is obtained.

[0039] Preparation Example 4

[0040] Preparation Example 4 provides a composite aerogel, which is only different from Preparation Example 1 in that cerium sulfide is omitted in step (b).

[0041] (II) Examples

[0042] Example 1

[0043] Example 1 provides a preparation method of an adsorption particle electrode for wastewater treatment, comprising the following steps:

[0044] (1) According to the usage ratio of zinc nitrate, vanadium nitrate, scandium nitrate, cetyltrimethylammonium bromide and water, 1 mol: 0.1 mol: 0.08 mol: 0.4 mol: 13 L, zinc nitrate, vanadium nitrate, scandium nitrate and cetyltrimethylammonium bromide are added to water, stirred and dissolved at 70°C, 1 mol / L lithium hydroxide solution is used to adjust the pH to 8 and incubate and stir for 2 h, the solid material is filtered, dried and calcined at 600°C for 4 h to obtain modified mesoporous zinc oxide;

[0045] (2) According to the usage ratio of modified mesoporous zinc oxide, composite aerogel and water, 1 mg: 9 mg: 1.2 mL, the modified mesoporous zinc oxide is added to water and ultrasonically dispersed to obtain a dispersion liquid; the composite aerogel of Preparation Example 1 is soaked in the dispersion liquid for 25 h, the solid material is filtered out, washed repeatedly and dried, and the dried solid material is ground and sieved through a 100 mesh sieve.

[0046] The present example also provides an adsorption particle electrode for wastewater treatment, which is prepared by the above preparation method; the scanning electron microscope image of the adsorption particle electrode is shown in Figure 1 .

[0047] Example 2

[0048] Example 2 provides a preparation method of an adsorption particle electrode for wastewater treatment, comprising the following steps:

[0049] (1) According to the usage ratio of zinc nitrate, vanadium nitrate, scandium nitrate, cetyltrimethylammonium bromide and water, 1 mol: 0.05 mol: 0.05 mol: 0.3 mol: 10 L, zinc nitrate, vanadium nitrate, scandium nitrate and cetyltrimethylammonium bromide are added to water, stirred and dissolved at 70°C, 1 mol / L lithium hydroxide solution is used to adjust the pH to 7.5 and incubate and stir for 1 h, the solid material is filtered, dried and calcined at 500°C for 3 h to obtain modified mesoporous zinc oxide;

[0050] (2) According to the mass ratio of modified mesoporous zinc oxide to composite aerogel 1:8, the modified mesoporous zinc oxide was added into water and uniformly dispersed by ultrasonic to obtain a dispersion liquid; the composite aerogel prepared in Preparation Example 2 was soaked in the dispersion liquid for 20 h, and the solid substance was filtered out, washed repeatedly and dried, and then ground and sieved through a 100-mesh sieve to obtain the product.

[0051] The present embodiment also provides an adsorbing particle electrode for wastewater treatment, which is prepared by the above preparation method.

[0052] Example 3

[0053] Example 3 provides a preparation method of an adsorbing particle electrode for wastewater treatment, which comprises the following steps:

[0054] (1) According to the ratio of zinc nitrate, vanadium nitrate, scandium nitrate, cetyltrimethylammonium bromide and water 1 mol:0.15 mol:0.1 mol:0.5 mol:16 L, the zinc nitrate, vanadium nitrate, scandium nitrate and cetyltrimethylammonium bromide were added into water, stirred and dissolved at 80°C, the pH was adjusted to 8.5 using 1 mol / L lithium hydroxide solution and incubated and stirred for 3 h, the solid substance was filtered out, dried and calcined at 700°C for 5 h to obtain modified mesoporous zinc oxide;

[0055] (2) According to the mass ratio of modified mesoporous zinc oxide to composite aerogel 1:10, the modified mesoporous zinc oxide was added into water and uniformly dispersed by ultrasonic to obtain a dispersion liquid; the composite aerogel prepared in Preparation Example 3 was soaked in the dispersion liquid for 30 h, and the solid substance was filtered out, washed repeatedly and dried, and then ground and sieved through a 100-mesh sieve to obtain the product.

[0056] The present embodiment also provides an adsorbing particle electrode for wastewater treatment, which is prepared by the above preparation method.

[0057] Comparative Example 3

[0058] Comparative Example 1

[0059] Comparative Example 1 is basically the same as Example 1, except that no vanadium nitrate and scandium nitrate are added in step (1) for preparing the modified mesoporous zinc oxide, i.e., mesoporous zinc oxide is used instead of the modified mesoporous zinc oxide.

[0060] Comparative Example 2

[0061] Comparative Example 2 is basically the same as Example 1, except that no vanadium nitrate and scandium nitrate are added in step (1) for preparing the modified mesoporous zinc oxide, and vanadic oxide and scandium oxide in equal molar amounts of vanadium nitrate and scandium nitrate are additionally added in the dispersion liquid in step (2).

[0062] Comparative Example 3

[0063] Comparative Example 3 is basically the same as Example 1, except that the composite aerogel in step (2) is replaced by the composite aerogel of Preparation Example 4.

[0064] (IV) Test Examples

[0065] The adsorptive particulate electrodes prepared in Examples 1-3 and Comparative Examples 1-3 above were subjected to the following performance tests.

[0066] Pollutant degradation test: 500 mL of simulated wastewater with an initial concentration of 25 mg / L of Rhodamine B was used, with a Ti plate as the cathode and a RuO2 / Ti plate as the anode, the working area in the solution was 3 cm*5 cm, the distance between the cathode and anode was 4 cm, 0.05 mol of sodium sulfate was added as an electrolyte, and 10 g / L of each adsorptive particulate electrode was added; a bias of 0.5 V was applied, and a xenon lamp light source with an AM1.5G filter was used for vertical irradiation, the absorbance was tested every 10 min using a UV-Vis spectrophotometer and the degradation rate was calculated, the degradation rate = (1-A t / A0) x 100%, where A0 is the absorbance of the solution before irradiation, and A t is the absorbance of the solution at irradiation time t; the degradation rate after 1 h was calculated, and the results are shown in Table 1 and Figure 2 .

[0067] Stability test: to investigate the reusability of the adsorptive particulate electrodes prepared in Examples 1-3 and Comparative Examples 1-3, after each degradation test, the adsorptive particulate electrodes were removed and dried in a forced air drying oven, and then reused, and the degradation rate of the organic pollutant Rhodamine B was calculated after the 10th use, and the results are shown in Table 1.

[0068] Table 1: Results of degradation and stability tests of adsorptive particulate electrodes

[0069]

[0070] As can be seen from Table 1, the adsorptive particulate electrodes prepared in Examples 1-3 of the present application have excellent performance in removing Rhodamine B from wastewater, with high degradation rate, fast degradation rate, and reusability.

[0071] Compared with example 1, comparative example 1 replaces the scandium-vanadium bimetallic doped mesoporous zinc oxide with unmodified mesoporous zinc oxide, comparative example 2 directly mixes the mesoporous zinc oxide with scandium oxide and vanadium oxide, and comparative example 3 omits cerium sulfide in the composite aerogel. The degradation effect and the 10th degradation rate of comparative examples 1-3 all decrease to different degrees. Specific analysis shows that: on the one hand, the mesoporous zinc oxide doped with scandium and vanadium bimetallic is loaded in the particle electrode, the zinc oxide can generate hydroxyl radicals through electrocatalysis, and can also generate electron-hole pairs under the catalysis of light to form superoxide radicals and hydroxyl radicals, respectively, which can decompose pollutants in water into CO2 and H2O; and the mesoporous structure has a large specific surface area, which can provide rich active sites and enhance the adsorption capacity of pollutants, realizing the adsorption and photoelectric synergistic catalytic treatment of wastewater. However, the light response range of zinc oxide is narrow, and it is easy to cause photo corrosion in the cycle process. The present application modifies it by using scandium and vanadium co-doping, which can adjust the energy band structure of zinc oxide, expand its light response range and improve the degradation rate. On the other hand, the present application uses nickel-iron hydrotalcite and cerium sulfide composite aerogel as a carrier. The nickel-iron hydrotalcite has a two-dimensional layered structure and rich active sites, which can adsorb pollutants in water through interlayer anion exchange and catalytically degrade through the oxidation and reduction of nickel and iron ions; the cerium sulfide has good conductivity and redox properties, and can improve the electron transport rate and catalytic activity when combined with nickel-iron hydrotalcite, and can form sulfur vacancies to inhibit the attachment and growth of microorganisms, maintaining the long-term stability of the particle electrode; the aerogel has a stable porous network structure, which not only provides an adsorption channel, but also ensures the cycle stability of the particle electrode.

[0072] Finally, it should be pointed out that the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit it. The basic principles and main features of the present application have been described in the above specific embodiments, and some modifications or replacements can be made on the basis of the present application, but these modifications or replacements do not make the corresponding technical solutions deviate from the scope of the present application.

Claims

1. A method for preparing an adsorption particle electrode for wastewater and waste liquid treatment, characterized in that, Includes the following steps: (1) Add zinc salt, vanadium salt, scandium salt and hexadecyltrimethylammonium bromide to water and stir. Adjust the pH at 70-80℃ and continue stirring. After filtration, drying and calcination, modified mesoporous zinc oxide is obtained. (2) The modified mesoporous zinc oxide is dispersed in water to obtain a dispersion; The composite aerogel was immersed in the dispersion for 20-30 hours, and then filtered, washed, dried, and ground to obtain the adsorption particle electrode. The composite aerogel is prepared by the following process: (a) Add nickel salt, iron salt and urea to water, adjust the pH to 9-12 and carry out hydrothermal reaction, filter and dry to obtain nickel-iron hydrotalcite; (b) The nickel-iron hydrotalcite and cerium sulfide were dispersed in N-methylpyrrolidone, polypyrrole was added and stirred to react, and the composite aerogel was obtained after freeze-drying.

2. The method for preparing the adsorption particle electrode for wastewater and waste liquid treatment according to claim 1, characterized in that, The molar ratio of zinc salt, vanadium salt, scandium salt and hexadecyltrimethylammonium bromide in step (1) is 1:(0.05-0.15):(0.05-0.1):(0.3-0.5).

3. The method for preparing the adsorption particle electrode for wastewater and waste liquid treatment according to claim 1, characterized in that, The pH value in step (1) is adjusted to 7.5-8.5; the stirring time is 1-3 hours.

4. The method for preparing the adsorption particle electrode for wastewater and waste liquid treatment according to claim 1, characterized in that, The calcination temperature in step (1) is 500-700℃ and the time is 3-5h.

5. The method for preparing an adsorption particle electrode for wastewater and waste liquid treatment according to claim 1, characterized in that, The molar ratio of nickel salt, iron salt and urea in step (a) is 1:(3-4):(12-24); the hydrothermal reaction temperature is 130-160℃ and the time is 8-12h.

6. The method for preparing the adsorption particle electrode for wastewater and waste liquid treatment according to claim 1, characterized in that, The mass ratio of nickel-iron hydrotalcite, cerium sulfide and polypyrrole in step (b) is 10:0.5-1.5:1-2; the stirring reaction time is 1-5 h.

7. The method for preparing the adsorption particle electrode for wastewater and waste liquid treatment according to claim 1, characterized in that, The mass ratio of the modified mesoporous zinc oxide to the composite aerogel in step (2) is 1:8-10.

8. An adsorption particle electrode for wastewater and waste liquid treatment, characterized in that, It is prepared by the method for preparing adsorption particulate electrode for wastewater and waste liquid treatment according to any one of claims 1-7.

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