阅读说明：本技术 一种以黑臭水体底泥为原料制备活性炭的方法 (Method for preparing activated carbon by taking black and odorous water body bottom mud as raw material ) 是由 林志 左静 秦丰林 沈霞 于 2021-09-14 设计创作，主要内容包括：本发明公开了一种以黑臭水体底泥为原料制备活性炭的方法,包括以下具体步骤：制备底泥初级活性炭、制备初级活化炭、制备次级活化炭、制备次级底泥活化炭和制备底泥活化炭。本发明中底泥活性炭经过多次活化可有效提高其比表面积、孔隙度以及吸附性能。(The invention discloses a method for preparing activated carbon by taking black and odorous water body bottom mud as a raw material, which comprises the following specific steps: preparing primary activated carbon of the bottom mud, preparing primary activated carbon, preparing secondary activated carbon of the bottom mud and preparing activated carbon of the bottom mud. The bottom sludge activated carbon can effectively improve the specific surface area, porosity and adsorption performance after being activated for many times.)

1. A method for preparing activated carbon by taking black and odorous water body bottom mud as a raw material is characterized by comprising the following specific steps:

s1, preparing primary activated carbon of bottom mud: dehydrating the black and odorous substrate sludge until the water content is lower than 60%, drying at 105 ℃ for 6-8 h, mixing with agricultural wastes, and adding N₂Carbonizing for 1h at 300 ℃ under protection, then carbonizing for 1h at 650-700 ℃, introducing CO₂Obtaining primary activated carbon of the bottom mud;

s2, preparing primary activated carbon: crushing the primary activated carbon of the bottom mud, sieving the crushed primary activated carbon by a sieve of 60-100 meshes, adding an activating agent, and soaking for 18-24 hours to obtain primary activated carbon;

s3, preparing secondary activated carbon: centrifuging and filtering the primary activated carbon, drying at 105 ℃ for 3 hours, and then performing pyrolysis, oxidation and activation at 800-900 ℃ for 1-2 hours to obtain secondary activated carbon;

s4, preparing secondary sediment activated carbon: adding 3mol/L hydrofluoric acid into the secondary activated carbon, oscillating for 2h at a constant temperature of 80 ℃, performing deliming treatment to obtain delimed carbon, washing the delimed carbon to be neutral by using distilled water, and removing redundant water-soluble ions to obtain secondary bottom mud activated carbon;

s5, preparing bottom sludge activated carbon: adding secondary bottom sludge activated carbon to Fe²⁺And Fe³⁺And (3) magnetically stirring the mixed solution for 30min, carrying out water bath at 70 ℃, dropwise adding a strong alkaline solution, reacting for 1h, washing until the supernatant is neutral, and drying at 60 ℃ to obtain the final substrate sludge activated carbon.

2. The method for preparing activated carbon from black and odorous water body bottom mud as a raw material according to claim 1, wherein in the step S1, the agricultural waste is one or more of wheat straw, corn stalk, straw, corncob, bamboo sawdust, fruit shell, wheat bran, peanut shell, coconut shell, bagasse, wood dust, tree branch and jute waste.

3. The method for preparing activated carbon from black and odorous water body bottom sediment as claimed in claim 1, wherein in the step S1, the agricultural waste has a diameter of 0.2-2 cm and a length of 0.5-2 cm.

4. The method for preparing activated carbon from black and odorous water body bottom mud as a raw material according to claim 1, wherein the mass ratio of the dried black and odorous water body bottom mud to agricultural waste is (1: 3) - (1: 5) in the step S1.

5. The method for preparing activated carbon from black and odorous water body bottom mud as a raw material according to claim 1, wherein in the step S1, the temperature rise rate is 15-20 ℃/min during the carbonization process at 650-700 ℃.

6. The method for preparing activated carbon from black and odorous water body bottom mud as claimed in claim 1, wherein in step S2, the activating agent is K₂CO₃、H₃PO₄And (NH)₄)₂PO₄The concentration of one of the two is 2-3 mol/L.

7. The method for preparing activated carbon from black and odorous water body bottom mud as a raw material according to claim 1, wherein in the step S2, the mass ratio of the primary activated carbon of the bottom mud to the activating agent is 1: (1-3).

8. The method for preparing activated carbon from black and odorous water body bottom mud as claimed in claim 1, wherein in step S5, Fe²⁺And Fe³⁺The mixed solution is FeSO₄And FeCl₃Mixed solution of (2), FeSO₄With FeCl₃The molar ratio of (1: 2) to (1: 3).

9. The method for preparing activated carbon from black and odorous water body bottom mud as claimed in claim 1, wherein in step S5, Fe²⁺And Fe³⁺The mass ratio of the mixed solution to the secondary bottom mud activated carbon is (3-5): 1.

Technical Field

The invention belongs to the technical field of water environment treatment, and particularly relates to a method for preparing activated carbon by taking black and odorous water body bottom mud as a raw material.

Background

The treatment of black and odorous water is the most popular problem in water environment treatment at present and is the most difficult environmental problem to treat. The odor and bad sensory experience generated by urban black and odorous water directly influence the normal production and life of nearby residents, and the problem of secondary pollution caused by the release of nitrogen and phosphorus nutrients, oxygen consuming substances, heavy metals, refractory organic pollutants and the like in the bottom sediment is the main reason for the difficulty in water treatment.

The black and odorous bottom sludge is prepared into the activated carbon, so that the reduction and harmlessness of the bottom sludge can be facilitated, the economic value and the social value of the bottom sludge are improved, and the conventional preparation method of the sludge activated carbon mainly comprises pyrolysis, chemical activation and physical and chemical activation methods. Patent CN106560236A discloses a sludge activated carbon with continuous pore size distribution characteristics for sewage treatment and a preparation method thereof, wherein the average specific surface area of the sludge activated carbon is 400-450 m²The method comprises the following steps of (1)/g, the pore diameters are continuously distributed at 0.5-50 nm, sludge and a compound activator aqueous solution are uniformly mixed and soaked, a binder is added for forming, a forming raw material is prepared, carbonization is carried out in nitrogen, a mixed gas of water vapor and nitrogen is introduced into a reaction system, the mixed gas of water vapor and nitrogen is stopped being introduced after the reaction is finished, the nitrogen is continuously introduced into the reaction system, natural cooling is carried out, and washing is carried out to be neutral. In view of the above, there is a need for an improvement of the conventional sludge activated carbon preparation method.

Disclosure of Invention

In order to solve the defects of the prior art, the invention aims to provide a method for preparing activated carbon by taking black and odorous water body bottom mud as a raw material.

In order to achieve the above object, the present invention adopts the following technical solutions:

a method for preparing activated carbon by taking black and odorous water body bottom mud as a raw material comprises the following specific steps:

s1, preparing primary activated carbon of bottom mud: dehydrating the black and odorous substrate sludge until the water content is lower than 60%, drying at 105 ℃ for 6-8 h, mixing with agricultural wastes, and adding N₂Carbonizing for 1h at 300 ℃ under protection, then carbonizing for 1h at 650-700 ℃, introducing CO₂Obtaining primary activated carbon of the bottom mud;

s2, preparing primary activated carbon: crushing the primary activated carbon of the bottom mud, sieving the crushed primary activated carbon by a sieve of 60-100 meshes, adding an activating agent, and soaking for 18-24 hours to obtain primary activated carbon;

s3, preparing secondary activated carbon: centrifuging and filtering the primary activated carbon, drying at 105 ℃ for 3 hours, and then performing pyrolysis, oxidation and activation at 800-900 ℃ for 1-2 hours to obtain secondary activated carbon;

s4, preparing secondary sediment activated carbon: adding 3mol/L hydrofluoric acid into the secondary activated carbon, oscillating for 2h at a constant temperature of 80 ℃, performing deliming treatment to obtain delimed carbon, washing the delimed carbon to be neutral by using distilled water, and removing redundant water-soluble ions to obtain secondary bottom mud activated carbon;

s5, preparing bottom sludge activated carbon: adding secondary bottom sludge activated carbon to Fe²⁺And Fe³⁺And (3) magnetically stirring the mixed solution for 30min, carrying out water bath at 70 ℃, dropwise adding a strong alkaline solution, reacting for 1h, washing until the supernatant is neutral, and drying at 60 ℃ to obtain the final substrate sludge activated carbon.

Preferably, in the step S1, the agricultural waste is one or more of wheat straw, corn stalk, straw, corncob, bamboo sawdust, fruit shell, wheat bran, peanut shell, coconut shell, bagasse, wood chip, tree branch and jute waste.

More preferably, in step S1, the agricultural waste has a diameter of 0.2-2 cm and a length of 0.5-2 cm.

More preferably, in the step S1, the mass ratio of the black odorous bottom mud to the agricultural waste after drying is (1: 3) - (1: 5).

Further preferably, in the step S1, the temperature increase rate is 15 to 20 ℃/min during the carbonization process at 650 to 700 ℃.

Specifically, in the foregoing step S2, the activating agent is K₂CO₃、H₃PO₄And (NH)₄)₂PO₄The concentration of one of the two is 2-3 mol/L.

Preferably, in the foregoing step S2, the mass ratio of the sediment primary activated carbon to the activating agent is 1: (1-3).

Still preferably, in the aforementioned step S5, Fe²⁺And Fe³⁺The mixed solution is FeSO₄And FeCl₃Mixed solution of (2), FeSO₄With FeCl₃The molar ratio of (1: 2) to (1: 3).

More preferably, in the aforementioned step S5, Fe²⁺And Fe³⁺Mixing the solution with secondary bottom mudThe mass ratio of the charcoal is (3-5): 1.

the invention has the advantages that:

(1) the agricultural and forestry waste particles are added, so that the bottom mud carbonization rate can be accelerated, the carbonization effect and the carbon content are improved, a carbon skeleton is formed, the specific surface area and the porosity of the bottom mud biomass carbon are improved, and the energy consumption and the carbonization cost in the carbonization process are reduced;

(2) in the invention, CO is introduced in the carbonization process₂The primary activation is finished, the activating agent is infiltrated into the bottom mud carbon, the secondary activation is finished, the porosity and the specific surface area of the activated carbon are improved through the two-time activation, the adsorption performance is effectively improved, and the FeSO is infiltrated₄And FeCl₃And activating the activated carbon for the third time, wherein the specific surface area, the porosity and the adsorption performance of the activated carbon can be effectively improved through multiple times of activation, and the iodine adsorption value of the obtained substrate sludge activated carbon is higher than 1000 mg/g.

Drawings

FIG. 1 is an SEM photograph of a sediment-activated carbon obtained in example 1 of the present invention;

FIG. 2 is an SEM photograph of the bottom sediment activated carbon obtained in example 2 of the present invention;

FIG. 3 is an SEM photograph of the bottom sediment-activated carbon obtained in example 3 of the present invention.

Detailed Description

The invention is described in detail below with reference to the figures and the embodiments.

Example 1

A method for preparing activated carbon by taking black and odorous water body bottom mud as a raw material comprises the following specific steps:

s1, preparing primary activated carbon of bottom mud: dehydrating the black and odorous substrate sludge until the water content is lower than 60%, drying at 105 ℃ for 6-8 h, mixing with agricultural waste wheat straws, wherein the mass ratio of the dried black and odorous substrate sludge to the wheat straws is 1: 3, the diameter of the wheat straw is 0.2-2 cm, the length of the wheat straw is 0.5-2 cm, and the wheat straw is in the range of N₂Carbonizing for 1h at 300 ℃ under protection, then carbonizing for 1h at 650-700 ℃, wherein the temperature rise rate is 15-20 ℃/min in the carbonization process, and introducing CO₂Obtaining primary activated carbon of the bottom mud;

S2preparing primary activated carbon: crushing the primary activated carbon of the bottom mud, sieving the crushed primary activated carbon with a 60-mesh sieve, and adding an activating agent K with the concentration of 2-3 mol/L₂CO₃The mass ratio of the primary activated carbon of the bottom mud to the activating agent is 1: 1, dipping for 20h to obtain primary activated carbon;

s3, preparing secondary activated carbon: centrifuging and filtering the primary activated carbon, drying at 105 ℃ for 3 hours, and then performing pyrolysis, oxidation and activation at 800-900 ℃ for 1-2 hours to obtain secondary activated carbon;

s4, preparing secondary sediment activated carbon: adding 3mol/L hydrofluoric acid into the secondary activated carbon, oscillating for 2h at a constant temperature of 80 ℃, performing deliming treatment to obtain delimed carbon, washing the delimed carbon to be neutral by using distilled water, and removing redundant water-soluble ions to obtain secondary bottom mud activated carbon;

s5, preparing bottom sludge activated carbon: adding the secondary bottom mud activated carbon to 0.1mol/L FeSO₄And FeCl₃In the mixed solution of (1), wherein Fe²⁺And Fe³⁺The mass ratio of the mixed solution to the secondary bottom sediment activated carbon is 3: 1, FeSO₄With FeCl₃The molar ratio of (1: 2) - (1: 3), magnetically stirring for 30min, carrying out water bath at 70 ℃, dropwise adding 30mL of 2mol/L NaOH solution, reacting for 1h, washing with water until the supernatant is neutral, and drying at 60 ℃ to obtain the final sediment activated carbon.

Example 2

A method for preparing activated carbon by taking black and odorous water body bottom mud as a raw material comprises the following specific steps:

s1, preparing primary activated carbon of bottom mud: dehydrating the black and odorous substrate sludge until the water content is lower than 60%, drying at 105 ℃ for 8h, mixing with agricultural waste bamboo chips, wherein the mass ratio of the dried black and odorous substrate sludge to the bamboo chips is 1: 4, the diameter of the bamboo dust is 0.2-2 cm, the length is 0.5-2 cm, and the content of the bamboo dust is N₂Carbonizing for 1h at 300 ℃ under protection, then carbonizing for 1h at 650-700 ℃, wherein the temperature rise rate is 15-20 ℃/min in the carbonization process, and introducing CO₂Obtaining primary activated carbon of the bottom mud;

s2, preparing primary activated carbon: crushing the primary activated carbon of the bottom mud, sieving the crushed primary activated carbon with a 80-mesh sieve, and adding an activating agent H with the concentration of 2-3 mol/L₃PO₄The mass ratio of the primary activated carbon of the bottom mud to the activating agent is 1: 2, soaking inSoaking for 18h to obtain primary activated carbon;

s3, preparing secondary activated carbon: centrifuging and filtering the primary activated carbon, drying at 105 ℃ for 3 hours, and then performing pyrolysis, oxidation and activation at 800-900 ℃ for 1-2 hours to obtain secondary activated carbon;

s4, preparing secondary sediment activated carbon: adding 3mol/L hydrofluoric acid into the secondary activated carbon, oscillating for 2h at a constant temperature of 80 ℃, performing deliming treatment to obtain delimed carbon, washing the delimed carbon to be neutral by using distilled water, and removing redundant water-soluble ions to obtain secondary bottom mud activated carbon;

s5, preparing bottom sludge activated carbon: adding the secondary bottom mud activated carbon to 0.1mol/L FeSO₄And FeCl₃In the mixed solution of (1), wherein Fe²⁺And Fe³⁺The mass ratio of the mixed solution to the secondary bottom sediment activated carbon is 4: 1, FeSO₄With FeCl₃The molar ratio of (1: 2) - (1: 3), magnetically stirring for 30min, carrying out water bath at 70 ℃, dropwise adding 30mL of 2mol/L NaOH solution, reacting for 1h, washing with water until the supernatant is neutral, and drying at 60 ℃ to obtain the final sediment activated carbon.

Example 3

A method for preparing activated carbon by taking black and odorous water body bottom mud as a raw material comprises the following specific steps:

s1, preparing primary activated carbon of bottom mud: dehydrating the black and odorous bottom mud until the water content is lower than 60%, drying at 105 ℃ for 6-8 h, mixing with branches of agricultural wastes, wherein the mass ratio of the dried black and odorous bottom mud to the branches is 1: 5, the diameter of the branch is 0.2-2 cm, the length is 0.5-2 cm, and the branch is in the N range₂Carbonizing for 1h at 300 ℃ under protection, then carbonizing for 1h at 650-700 ℃, wherein the temperature rise rate is 15-20 ℃/min in the carbonization process, and introducing CO₂Obtaining primary activated carbon of the bottom mud;

s2, preparing primary activated carbon: crushing the primary activated carbon of the bottom mud, sieving the crushed primary activated carbon with a 100-mesh sieve, and adding an activating agent (NH) with the concentration of 2-3 mol/L₄)₂PO₄The mass ratio of the primary activated carbon of the bottom mud to the activating agent is 1: 3, dipping for 20 hours to obtain primary activated carbon;

s3, preparing secondary activated carbon: centrifuging and filtering the primary activated carbon, drying at 105 ℃ for 3 hours, and then performing pyrolysis, oxidation and activation at 800-900 ℃ for 1-2 hours to obtain secondary activated carbon;

s4, preparing secondary sediment activated carbon: adding 3mol/L hydrofluoric acid into the secondary activated carbon, oscillating for 2h at a constant temperature of 80 ℃, performing deliming treatment to obtain delimed carbon, washing the delimed carbon to be neutral by using distilled water, and removing redundant water-soluble ions to obtain secondary bottom mud activated carbon;

s5, preparing bottom sludge activated carbon: adding the secondary bottom mud activated carbon to 0.1mol/L FeSO₄And FeCl₃In the mixed solution of (1), wherein Fe²⁺And Fe³⁺The mass ratio of the mixed solution to the secondary bottom sediment activated carbon is 5: 1, FeSO₄With FeCl₃The molar ratio of (1: 2) - (1: 3), magnetically stirring for 30min, carrying out water bath at 70 ℃, dropwise adding 30mL of 2mol/L NaOH solution, reacting for 1h, washing with water until the supernatant is neutral, and drying at 60 ℃ to obtain the final sediment activated carbon.

Performance test

(1) Scanning the bottom sediment activated carbon obtained in the embodiments 1 to 3 by using an SEM electron microscope, wherein electron microscope images are shown in figures 1 to 3, and the figures 1 to 3 show that the prepared bottom sediment activated carbon has a pore structure, so that the adsorption performance of the activated carbon is effectively improved.

(2) Properties of the bottom sediment activated carbon obtained in examples 1 to 3 and a comparative example (a commercially available general activated carbon) were measured, and the results of the measurements are shown in Table 1.

TABLE 1 determination of the Properties of the activated carbon samples

As can be seen from table 1, compared with the comparative example, the bottom sediment activated carbon prepared in examples 1 to 3 has higher iodine adsorption value, specific surface area and pore volume, and can effectively improve the adsorption performance of the activated carbon.

(3) Four portions of black and odorous water 1L are collected, 20g of the activated carbon in the examples 1-3 and the comparative example (the common activated carbon sold in the market) are respectively added, the dissolved oxygen content, the ammonia nitrogen content and the chemical oxygen demand are detected, and the detection results are shown in Table 2.

TABLE 2 indexes of black smelly water after adsorption by activated carbon

As can be seen from Table 2, compared with the comparative example, the bottom sediment activated carbon prepared in the examples 1 to 3 can effectively reduce the chemical oxygen demand and the ammonia nitrogen content in the black and odorous water body, and improve the dissolved oxygen content in the water body.

The foregoing illustrates and describes the principles, general features, and advantages of the present invention. It should be understood by those skilled in the art that the above embodiments do not limit the present invention in any way, and all technical solutions obtained by using equivalent alternatives or equivalent variations fall within the scope of the present invention.