CN110898825A

CN110898825A - Heavy metal super-enriched biomass charcoal catalyst and preparation method and application thereof

Info

Publication number: CN110898825A
Application number: CN201911284720.4A
Authority: CN
Inventors: 丁大虎; 周亮; 蔡天明; 陈立伟
Original assignee: Nanjing Agricultural University
Current assignee: Nanjing Agricultural University
Priority date: 2019-12-13
Filing date: 2019-12-13
Publication date: 2020-03-24

Abstract

The invention discloses a heavy metal hyper-enrichment biomass charcoal catalyst and a preparation method and application thereof, wherein the preparation method comprises the following steps: (1) dissolving carbonate in water to obtain a solution; (2) adding the sedum alfredii powder into the solution, and stirring to obtain a suspension; (3) volatilizing the water in the suspension, and grinding to obtain solid powder; (4) wrapping the solid powder with aluminum foil paper, calcining, cooling and grinding to obtain black powder; (5) soaking black powder in acid solution, stirring, filtering, soaking in water, separating solid and liquid, washing the solid to neutral, drying, grinding, and sieving. Has the advantages that: the heavy metal hyper-enriched biomass charcoal activated hydrogen persulfate has a synergistic effect, the degradation effect is obviously higher than that of a single catalyst and hydrogen persulfate, the specific surface area is large, and more reaction sites can be provided.

Description

Heavy metal super-enriched biomass charcoal catalyst and preparation method and application thereof

Technical Field

The invention belongs to the field of biomass charcoal materials, and particularly relates to a preparation method of a heavy metal hyper-enrichment biomass charcoal catalyst and application of the heavy metal hyper-enrichment biomass charcoal catalyst in organic wastewater treatment.

Background

With the development of industrialization, the problem of water pollution is receiving more and more attention, and the problem of organic pollution is particularly outstanding. The biological treatment method is a commonly used process for removing organic pollutants in wastewater, but for organic wastewater which has strong toxicity, high concentration and difficult biodegradation, the biological treatment method often cannot achieve an ideal removal effect. In recent years, advanced oxidation technologies based on strongly oxidizing radicals (hydroxyl radicals) have received attention from numerous researchers. The free gene has strong oxidizing property, can realize non-toxicity or low-toxicity of refractory organic matters, and can mineralize the organic matters into water and carbon dioxide. The advanced oxidation wastewater treatment technology taking hydroxyl radicals as the leading factor mainly takes Fenton and Fenton-like methods as the leading factors, and is also the advanced oxidation wastewater treatment technology which is applied more in the current engineering.

With the continuous and deep research, the advanced oxidation wastewater treatment technology based on sulfate radicals is found to have better application prospects, and compared with the advanced oxidation water treatment technology taking hydroxyl radicals as the leading factor, the advanced oxidation wastewater treatment technology based on sulfate radicals has more advantages, and is mainly reflected in the following aspects: (1) sulfate radical free radical has stronger selectivity for degrading organic matters, and can almost degrade all organic pollutants in the wastewater; (2) sulfate radicals have higher oxidation potential (2.5-3.1V) and all oxidability is stronger; (3) the pH range applicable to the advanced oxidation technology based on sulfate radicals is wider (2-9); (4) the half-life of the sulfate radical is longer and more stable.

The biomass charcoal is mainly an adsorption material, but the heavy metal super-enriched biomass charcoal not only has better adsorption performance, but also has the characteristics of higher catalytic performance and easy separation because the biomass charcoal contains metal inside, and in addition, the preparation of the biomass charcoal can solve the treatment problem of heavy metal super-enriched plants, and is favorable for solving the problem of heavy metal pollution of soil. At present, no report related to heavy metal super-enriched biomass charcoal for degrading organic matters in wastewater exists.

Disclosure of Invention

The purpose of the invention is as follows: the invention aims to solve the technical problem of the prior art and provides a heavy metal hyper-enrichment biomass charcoal catalyst, a preparation method thereof and application thereof in organic wastewater treatment.

In order to solve the technical problem, the invention discloses a preparation method of a heavy metal hyper-enrichment biomass charcoal catalyst, which comprises the following steps:

(1) dissolving carbonate in water, and stirring uniformly to completely dissolve the carbonate to obtain a solution;

(2) adding rhodiola rosea powder into the solution obtained in the step (1), and magnetically stirring to obtain a suspension;

(3) volatilizing the water in the suspension obtained in the step (2), and grinding to obtain matcha solid powder;

(4) placing the solid powder obtained in the step (3) in a crucible, wrapping the crucible with inner and outer aluminum foil paper, placing the crucible in a muffle furnace for calcining, cooling and grinding to obtain black powder;

(5) and (4) soaking the black powder obtained in the step (4) in an acid solution, magnetically stirring, filtering, soaking in water again, carrying out solid-liquid separation, washing the solid to be neutral, drying, grinding and sieving to obtain the black powder.

In the step (1), the carbonate is potassium carbonate or sodium carbonate; the concentration of the carbonate is 0.1 to 0.3g/mL (preferably 0.2 g/mL).

In the step (2), the mass ratio of the carbonate to the sedum alfredii powder is 1-3: 1 (preferably 2: 1); the stirring speed is 100-300 rpm (preferably 200rpm), and the time is 3.5-4.0 h.

In the step (2), the atomic content of Zn in the sedum alfredii hance is 0.05-0.45%, and the atomic content of Cu is 0.05-0.50%; wherein, the preferable content is 0.25 percent of Zn, 0.13 percent of Cu, 86.7 percent of C, 4.52 percent of N and 8.40 percent of O; in the sedum alfredii hance, other metal Cd also exists, but the Cd does not have a catalytic effect. Before use, the sedum alfredii plants are washed by pure water for a plurality of times, dried in an oven at 80 ℃ for 12 hours and then crushed to have the particle size of less than 60 meshes.

Wherein said Zn and Cu are present in the form of oxides ZnO and CuO, which can act as catalysts to activate Persulfates (PS) or Peroxodisulfates (PMS) or H₂O₂Sulfate radicals or hydroxyl radicals are generated to degrade pollutants, and metal addition is not shown in the synthesis method, namely, no external metal is doped, so that the advantage is cost saving.

And (3) putting the suspension obtained in the step (2) into an oven at 80 ℃, and drying for 24 hours until the water is completely volatilized.

In the step (4), the calcining temperature is 400-800 ℃; the calcining time is 1.5-4 h, and the heating rate is 10 ℃/min.

Wherein the calcination temperature is preferably 400 ℃, 500 ℃, 600 ℃, 700 ℃ and 800 ℃; the calcination time is preferably 2 h.

In the step (5), the acid is 2M hydrochloric acid solution; the volume mass ratio of the acid dosage to the carbonate in the step (1) is 15-25 mL: 1g, to make it excessive, ensure K in the material₂CO₃Complete removal of (1); the stirring time is 4 hours, and the stirring speed is 100-200 rpm; soaking in water for 24 hr.

In the step (5), washing is carried out by using distilled water; the drying is air atmosphere drying; preferably, the drying temperature is 80 ℃, and the drying time is 24 hours; the mesh number of the screen is 80-120 meshes (preferably 100 meshes); .

The heavy metal hyper-enriched biomass charcoal catalyst prepared by the method is also within the protection scope of the invention.

The application of the heavy metal hyper-enrichment biomass charcoal catalyst in treating organic wastewater is also within the protection scope of the invention.

The application comprises the steps of adding a heavy metal hyper-enrichment biomass charcoal catalyst into waste water containing organic pollutants at room temperature to enable the solid content of the catalyst to be 0.01-0.3 g/L, and adding an oxidant to enable the catalyst to beThe concentration is 4 to 6mM, and the treatment is carried out for 1.5 to 3.0 hours under the neutral condition; wherein the oxidant is H₂O₂Or Persulfate (PS) or Peroxodisulfate (PMS), preferably persulfate and peroxodisulfate, more preferably peroxodisulfate.

Preferably, a heavy metal super-enriched biomass charcoal catalyst is added to enable the solid content to be 0.1 g/L; adding an oxidant to make the concentration of the oxidant 5.0 mM; the treatment time was 3 h.

The application of the biomass charcoal catalyst in treating organic wastewater is to activate hydrogen persulfate, persulfate and hydrogen peroxide to generate strong-oxidizing sulfate radicals or hydroxyl radicals or singlet oxygen by the biomass charcoal catalyst, so as to oxidize organic matters in the wastewater.

After the treatment by the method, the removal rate of the peroxodisulfate/MBK 800 system on organic pollutants can reach over 90 percent. Under the condition of proper conditions, the removal rate of the organic pollutants can reach nearly 100 percent, and the effect is very obvious.

Has the advantages that: compared with the prior art, the invention has the following advantages:

(1) the heavy metal hyper-enrichment biomass charcoal catalyst belongs to a water-insoluble system, and an organic wastewater system for activating peroxydisulfate to degrade belongs to a heterogeneous catalytic oxidation system.

(2) The heavy metal hyper-enriched biomass charcoal activated hydrogen persulfate has a synergistic effect, the degradation effect is obviously higher than that of a single catalyst and hydrogen persulfate, and the heavy metal hyper-enriched biomass charcoal has a large specific surface area and can provide more reaction sites.

(3) The heavy metal super-enriched biomass charcoal contains more metal oxides such as CuO and ZnO, and the heavy metal super-enriched biomass charcoal can be used as a catalyst to activate PMS or PS or H₂O₂The method generates sulfate radicals or hydroxyl radicals to degrade pollutants, thereby not only avoiding the doping of external metals, saving the cost, but also improving the catalytic effect to a great extent.

(4) The catalyst of the invention has less usage amount, can be carried out at normal temperature, does not need external energy, has simple operation and convenient recovery, and is suitable for the treatment of organic wastewater difficult to degrade.

Drawings

FIG. 1 is an electron micrograph of MBK800 prepared in example 1.

FIG. 2 is a comparison of the degradation effects of ciprofloxacin in example 2.

FIG. 3 is a comparison of the effect of ciprofloxacin treatment in example 3.

FIG. 4 is a comparison of the effect of ciprofloxacin treatment in example 4.

FIG. 5 is a comparison of the effect of ciprofloxacin treatment in example 5.

FIG. 6 is a mechanism study of degradation of ciprofloxacin in example 6.

Detailed Description

The invention will be better understood from the following examples. However, those skilled in the art will readily appreciate that the description of the embodiments is only for illustrating the present invention and should not be taken as limiting the invention as detailed in the claims.

Example 1: preparation of catalyst with sedum alfredii as raw material

(1) Weigh 12.0g K₂CO₃Dissolving the mixture in 60mL of distilled water, and uniformly stirring to completely dissolve the mixture to obtain a first mixed solution;

(2) adding 6.0g of sedum alfredii plant powder into the first mixed solution obtained in the step (1), and magnetically stirring for 4 hours at the rotating speed of 200rpm to obtain a suspension;

(3) drying the suspension obtained in the step (2) in an oven at 80 ℃ for 24 hours to completely volatilize the water, and grinding to obtain matcha solid powder;

(4) placing the solid brown powder obtained in the step (3) in a crucible, wrapping the inside and outside aluminum foil paper, placing the crucible in a muffle furnace for calcining for 2 hours at the temperature rising rate of 10 ℃/min and the calcining temperatures of 400 ℃, 500 ℃, 600 ℃, 700 and 800 ℃ respectively, cooling and grinding to obtain black powder;

(5) and (3) soaking the black powder obtained in the step (4) in 250mL of 2M HCl acid solution, magnetically stirring for 4h, filtering, soaking in distilled water for 24h, performing suction filtration and washing until the filtrate is neutral, drying at 80 ℃ for 24h, grinding, and sieving with a 100-mesh sieve to obtain the required catalyst, so as to obtain MBK400, MBK500, MBK600, MBK700 and MBK800(x represents the calcination temperature).

Comparative example 1: preparation of other Biomass charcoal catalysts

In the same way as in the example 1, the sedum alfredii plant powder in the step (2) is respectively replaced by peanut shells, wheat straws and activated sludge; and (4) the calcining temperature in the step (4) is 700 ℃, and the required catalyst is obtained and is respectively expressed by PSK700, WSK700 and ASK 700.

Comparative example 2:

the step (1) was removed as in example 1; the calcination temperature in the step (4) is 700 ℃, and the required catalyst is obtained and is represented by MBC 700.

The catalysts obtained in example 1, comparative example 1 and comparative example 2 were compared, and the results are shown in Table 1. Table 1 shows the results for K₂CO₃The specific surface area and the empty volume of the biomass charcoal material can be effectively improved through activation; with the increase of the calcining temperature, the specific surface area of the carbon material is continuously increased, and the specific surface area and the pore volume of the MBK800 are maximum; comparing the specific surface areas of different biomass carbon materials ASK700 (activated sludge), PSK700 (peanut shell) and WSK700 (wheat straw) calcined at 700 ℃, the specific surface area (figure 1) of the carbon material calcined by the sedum alfredii hance is the largest, and the sedum alfredii hance plant has a large amount of metal particles for different biomasses, so that the specific surface area of the carbon material can be increased, and the sedum alfredii hance plant has more prominent performance.

TABLE 1 specific surface area and pore volume of carbon materials prepared in example 1, comparative example 1 and comparative example 2

Sample (I)	Specific surface area (m)²/g)	Pore volume (cm)³/g)
			MBK400	584.9508	0.384316
MBK500	667.9625	0.395353
			MBK600	807.5189	0.462546
MBK700	973.8366	0.551942
			MBK800	1090.6835	0.609829
MBC700	427.8724	0.349682
			ASK700	791.3717	0.493941
PSK700	575.6295	0.400600
			WSK700	873.7361	0.548056

Example 2

The following three experiments were performed on the tests of treating ciprofloxacin wastewater by activating different oxidants with the heavy metal hyper-enrichment biomass charcoal catalyst MBKx prepared in example 1.

Test I: the conical flask is used as a reactor, the volume of the ciprofloxacin wastewater is 100mL, and the initial concentration of the ciprofloxacin is 80mg^-1Initial pH 7.04; the catalyst MBKx prepared in example 1 was added to the reactor to a solid content of 0.1g/L, magnetically stirred at 150rpm for 80min to reach adsorption equilibrium, 2.0mL of each different oxidizing agent was added to a concentration of 5.0mM, the reaction was carried out at room temperature, sampling was carried out periodically, and the residual ciprofloxacin concentration was determined by liquid chromatography.

Test II: no oxidant was added and the other conditions were the same as in test I.

Test III: the conical flask is used as a reactor, the volume of the ciprofloxacin wastewater is 100mL, and the initial concentration of the ciprofloxacin is 80mg^-1Initial pH 7.04; 2.0mL of each oxidizing agent was added to the reaction vessel to a concentration of 5.0mM, the reaction was carried out at room temperature, sampling was carried out at regular intervals, and the concentration of the remaining ciprofloxacin was measured by a liquid chromatograph.

The results in FIG. 2 show that the results are for H and H₂O₂Or sodium Persulfate (PS) or potassium hydrogen Persulfate (PMS), which both show a tendency that the catalytic effect of the catalyst increases with an increase in the preparation temperature; among them, MBK800 has the best removal efficiency on ciprofloxacin and shows the best catalytic performance. For three oxidation systems, the PMS oxidation system has the best removal effect on ciprofloxacin, and the PMS oxidation system has the worst effect on H₂O₂And (3) an oxidation system. Therefore, the PMS/MBK800 system can achieve the best treatment effect when used for treating ciprofloxacin waste water.

Example 3

And (3) a test for treating ciprofloxacin wastewater by activating hydrogen persulfate through the heavy metal super-enriched biomass charcoal catalyst MBKx prepared in example 1.

By using conical flasks as counterboresReactor, ciprofloxacin wastewater volume 100mL, ciprofloxacin initial concentration 80mg.L^-1Initial pH 7.04; the catalyst MBKx prepared in example 1 was charged into a reactor to a solid content of 0.1g/L, magnetically stirred at 150rpm for 80min to reach adsorption equilibrium, 2.0mL of each potassium hydrogen persulfate solution was added to a concentration of 5.0mM, the reaction was carried out at room temperature, samples were taken at regular intervals, and the residual ciprofloxacin concentration was measured by liquid chromatography.

The results of FIG. 3 show that adsorption is performed before-40-0 min, which aims to saturate the adsorption of the carbon material and facilitate the analysis of the respective functions of adsorption and catalysis, the trend of the change at the front section is caused by adsorption, and the trend at the rear end is caused by catalytic degradation; the subsequent time is catalytic degradation, the catalytic reaction is mainly 10min before the reaction, and the catalytic reaction rate constant k value of MBK800 is the maximum and reaches 0.1926min^-1Is obviously higher than the heavy metal super-enriched biomass charcoal material prepared at other preparation temperatures. The combination of figure 3 shows that MBK800 can achieve good removal effect by activating the hydrogen persulfate to catalytically degrade ciprofloxacin, and the removal rate can reach more than 90% within 3 hours. Therefore, the heavy metal hyper-enriched biomass charcoal catalyst of example 1 is successfully prepared, and good catalytic degradation effect is obtained.

Example 4

The conical flask is used as a reactor, the volume of the ciprofloxacin wastewater is 100mL, and the initial concentration of the ciprofloxacin is 80mg^-1Initial pH 7.04; the catalysts MBK700, ASK700, PSK700 and WSK700 prepared in example 1 were charged into a reactor to have a solid content of 0.1g/L, magnetically stirred at 150rpm for 40min to reach adsorption equilibrium, 2.0mL of potassium hydrogen persulfate solution was added to have a concentration of 5.0mM, reacted at room temperature, sampled at regular intervals, and the remaining ciprofloxacin concentration was measured by a liquid chromatograph.

The specific treatment results are shown in fig. 4, and the results in fig. 4 show that the adsorption effect of MBK700 on ciprofloxacin is the best, and 53% of ciprofloxacin can be adsorbed within 40 min. After the peroxydisulfate is activated, the catalytic degradation of the ciprofloxacin is mainly carried out 5-10min before the reaction, and the maximum degradation rate constant K of MBK700 is 0.1427, which indicates that the reaction is fastest. The removal rate of ciprofloxacin within 40min is also the highest MBK700 and can reach more than 90%.

The catalytic performance of the catalyst of the invention is obviously superior to that of carbon materials prepared by other biomasses.

Example 5

In order to verify whether the heavy metal super-enriched biomass carbon MBK800 and the peroxydisulfate have a synergistic effect, the following three groups of experiments are carried out.

Test I: the conical flask is used as a reactor, the volume of the ciprofloxacin wastewater is 100mL, and the initial concentration of the ciprofloxacin is 80mg^-1Initial pH 7.04; the catalyst MBK800 prepared in example 1 was charged into a reactor to have a solid content of 0.1g/L, magnetically stirred at 150rpm for 40min to reach adsorption equilibrium, 2.0mL of a potassium hydrogen persulfate solution was added to have a concentration of 5.0mM, reacted at room temperature, sampled at regular intervals, and the residual ciprofloxacin concentration was measured by a liquid chromatograph.

Test II: the catalyst was not added and the other conditions were the same as in test I.

Test III: the conditions were otherwise the same as for test I, without the addition of potassium hydrogen persulfate solution.

The treatment result is shown in fig. 5, as can be seen from fig. 5, the monopersulfate can only oxidize and remove about 15% of organic pollutants (ciprofloxacin), the monolithium charcoal MBK800 can remove about 60% of organic pollutants (ciprofloxacin), while the removal rate of the MBK800/PMS system on ciprofloxacin can reach about 90%, which is obviously superior to the sum of the removal rates of the monolithium charcoal MBK800 and the monopersulfate on ciprofloxacin, and the synergistic effect exists between the heavy metal super-enriched biomass charcoal MBK800 and the peroxodisulfate. The reason is that adsorption is saturated first, active sites on the surface of the carbon material are almost completely covered by pollutants, and when an oxidant is added, the slow removal rate is shown due to the reduction of active sites participating in the reaction; when the catalyst and the pollutant are added simultaneously, more reaction sites are exposed, so that the reaction is faster, and a synergistic effect is generated.

Example 6

The conical flask is used as a reactor, the volume of the ciprofloxacin wastewater is 100mL, and the initial concentration of the ciprofloxacin is 80mg^-1Initial pH 7.04; the reactor is charged with the product prepared in example 1Adding methanol, tert-butyl alcohol (TBA) and a lycopene quencher into MBK800 catalyst with solid content of 0.1g/L, magnetically stirring at 150rpm for 40min to reach adsorption balance, adding 2.0mL potassium hydrogen persulfate solution with concentration of 5.0mM, reacting at room temperature, sampling at regular time, and measuring the residual ciprofloxacin concentration by using a liquid chromatograph.

As shown in FIG. 6, it can be seen from FIGS. 6(a) and (b) that the MBK800/PMS system is not dominated by hydroxyl radicals and sulfate radicals, and FIG. 6(c) shows more significant degradation inhibition effect as the lycopene concentration increases, so that singlet oxygen in the reaction system can be found to play a major role in oxidatively degrading pollutants.

The invention provides a heavy metal hyper-enrichment biomass charcoal catalyst, a preparation method and an application concept and method thereof, and a plurality of methods and ways for realizing the technical scheme are provided, the above description is only a preferred embodiment of the invention, and it should be noted that, for a person skilled in the art, a plurality of improvements and decorations can be made without departing from the principle of the invention, and the improvements and decorations should also be regarded as the protection scope of the invention. All the components not specified in the present embodiment can be realized by the prior art.

Claims

1. A preparation method of a heavy metal hyper-enrichment biomass charcoal catalyst is characterized by comprising the following steps:

(1) dissolving carbonate in water to obtain a solution;

(2) adding rhodiola rosea powder into the solution obtained in the step (1), and stirring to obtain a suspension;

(3) volatilizing the moisture in the suspension obtained in the step (2), and grinding to obtain solid powder;

(4) wrapping the solid powder obtained in the step (3) with aluminum foil paper, calcining, cooling and grinding to obtain black powder;

(5) and (4) soaking the black powder obtained in the step (4) in an acid solution, stirring, filtering, soaking in water again, carrying out solid-liquid separation, washing the solid to be neutral, drying, grinding and sieving to obtain the black powder.

2. The method according to claim 1, wherein in the step (1), the carbonate is potassium carbonate or sodium carbonate; the concentration of the carbonate is 0.1-0.3 g/mL.

3. The preparation method according to claim 1, wherein in the step (2), the mass ratio of the carbonate to the sedum alfredii powder is 1-3: 1; the stirring speed is 100-300 rpm, and the time is 3.5-4.0 h; the content of Zn in the sedum alfredii hance is 0.05-0.45%, and the content of Cu is 0.05-0.50%.

4. The preparation method according to claim 1, wherein in the step (3), the suspension obtained in the step (2) is placed in an oven at 80 ℃ and dried until the moisture is completely volatilized.

5. The preparation method according to claim 1, wherein in the step (4), the calcining temperature is 400-800 ℃; the calcining time is 1.5-4 h.

6. The method according to claim 1, wherein in the step (5), the acid is a 2M hydrochloric acid solution; the volume mass ratio of the acid dosage to the carbonate in the step (1) is 15-25 mL: 1g of a compound; the mesh number of the sieve is 80-120 meshes.

7. The heavy metal super-enriched biomass charcoal catalyst prepared by the method of any one of claims 1 to 6.

8. The use of the heavy metal hyper-enriched biomass charcoal catalyst of claim 7 in the treatment of organic wastewater.

9. The application of the heavy metal hyper-enrichment biomass charcoal catalyst is characterized in that the heavy metal hyper-enrichment biomass charcoal catalyst is added into the waste water containing organic pollutants at room temperature to enable the solid content to be 0.01-0.3 g/L, the oxidant is added to enable the concentration to be 4-6 mM, and the waste water is treated for 1.5-3.0 hours under the neutral condition.

10. The application of the method as claimed in claim 9, wherein the heavy metal super-enriched biomass charcoal catalyst is added to make the solid content of the heavy metal super-enriched biomass charcoal catalyst be 0.1 g/L; adding an oxidant to make the concentration of the oxidant 5.0 mM; the oxidant is any one or combination of more of hydrogen peroxide, persulfate and hydrogen persulfate.