CN109019967B - Resource utilization method of iron mud generated by organic wastewater treatment by Fenton method - Google Patents

Abstract

The invention discloses a resource utilization method of iron mud generated by organic wastewater treatment by a Fenton method, which comprises the following steps: s1, breaking the residual chemical iron mud after the organic wastewater is subjected to Fenton method and activated carbon adsorption treatment into blocks, drying at 40-60 ℃ for 12-24 h, and grinding into powder to obtain primary iron mud; s2, adding sulfuric acid into the primary iron mud obtained in the step S1, stirring for 1.5 hours at the temperature of 65-75 ℃, performing suction filtration, and collecting filtrate and filter residues; s3, drying the filter residue obtained in the step S2 at 40-60 ℃ for 12-24 hours, pyrolyzing the filter residue at 200-800 ℃ for 1-2 hours in a nitrogen atmosphere, and naturally cooling the filter residue to room temperature to obtain carbon powder; and S4, recycling the carbon powder obtained in the step S3 in the process of treating the organic wastewater by activated carbon adsorption to form resource utilization of the iron mud. The method not only makes full use of iron mud resources, but also solves the problem of secondary pollution of iron mud by a Fenton oxidation method.

Description

Resource utilization method of iron mud generated by organic wastewater treatment by Fenton method

Technical Field

The invention belongs to the field of solid waste recycling treatment, and particularly relates to a recycling method of iron mud generated by organic wastewater treatment by a Fenton method.

Background

The Fenton oxidation method is an advanced oxidation technology which is newly raised in recent years, and the adoption of Fe is firstly discovered and adopted in 1894 by H.J.Fenton²⁺/H₂O₂The system can oxidize various organic matters.Since then, a great deal of research has been conducted by various scholars on the treatment of wastewater by the Fenton method. The oxidation mechanism of the Fenton process is that of Fe²⁺And H₂O₂Forming a Fenton reagent to form an oxidation system. It has the main functions as follows: on the one hand, oxidation of organic substances by means of catalytic H₂O₂The oxidation decomposition generates OH with extremely strong oxidability; on the other hand coagulation, Fe (OH) formed in the Fenton oxidation reaction₃The colloid has flocculation and adsorption functions, and can also remove partial organic matters in the wastewater, so the colloid is widely applied to the aspect of wastewater treatment, and has the characteristics of convenient operation, mature treatment process and excellent performance in the aspect of treating complex polluted water bodies, particularly in the paper-making industry, the chemical industry, the metallurgical industry, the pharmaceutical industry and the like. However, a large amount of agglomerated iron mud is generated after the Fenton treatment, and if the iron mud is not treated and recycled, the iron mud is difficult to dehydrate, the amount of the sludge is increased, the treatment cost is increased, the recycling reaction cannot be performed, and the iron mud contains a large amount of organic impurities besides iron and oxides thereof, so that if the iron mud cannot be properly treated, the secondary pollution problem is caused to the environment, and a large amount of iron mud resources are wasted. In order to prevent resource waste and iron sludge pollution, water plants generally dehydrate the iron sludge by methods such as filter pressing, flocculation and the like, and the treatment steps are complicated, the cost is high, and the aim of effective utilization is not achieved. If the iron slime is reasonably utilized, the purposes of environmental friendliness and ecological harmony are fulfilled by changing waste into valuable and extracting and recycling the iron slime. Therefore, the iron sludge resource needs to be reasonably utilized to realize the recycling of the iron sludge.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, provides a resource utilization method of iron mud generated by organic wastewater treatment by a Fenton method, and realizes resource recycling of Fenton iron mud.

In order to achieve the purpose, the invention adopts the technical scheme that:

a resource utilization method of iron mud generated by organic wastewater treatment by a Fenton method is characterized by comprising the following steps:

s1, breaking the residual chemical iron mud after the organic wastewater is subjected to Fenton method and activated carbon adsorption treatment into blocks, drying at 40-60 ℃ for 12-24 h, and then grinding into powder to obtain primary iron mud;

s2, adding dilute sulfuric acid into the primary iron mud obtained in the step S1, stirring for 1-2 hours at the temperature of 65-75 ℃, then performing suction filtration, and collecting filtrate and filter residues, wherein the mass ratio of the primary iron mud to the dilute sulfuric acid is 1: 1-1.5;

s3, drying the filter residue obtained in the step S2 at 40-60 ℃ for 12-24 hours, then putting the filter residue into a ceramic crucible, pyrolyzing the filter residue for 1-2 hours at 200-800 ℃ in a nitrogen atmosphere, and naturally cooling the filter residue to room temperature to obtain carbon powder;

and S4, recycling the carbon powder obtained in the step S3 in the process of treating the organic wastewater by activated carbon adsorption to form resource utilization of the iron mud.

Preferably, in S2, the mass fraction of dilute sulfuric acid is 25%.

Preferably, in S3, the pyrolysis temperature is 400 ℃ and the pyrolysis time is 1 h.

Preferably, in S2, the filtrate is reduced by iron powder to obtain ferrous sulfate solution, and the ferrous sulfate solution is concentrated and reused in the process of oxidation treatment of organic wastewater by the Fenton method.

Compared with the prior art, the invention has the following beneficial effects:

(1) according to the invention, moisture in the iron mud can be removed through drying, so that the sludge amount is reduced, the treatment cost is reduced, and the water content of the iron mud sample is determined to be 41.14%;

(2) according to the invention, the iron mud is treated by using sulfuric acid and pyrolyzed, so that the N, C content in the organic filter residue is increased, the aperture of the prepared carbon powder is reduced, the number of apertures is increased, and the adsorption effect on organic pollutants in the wastewater is improved;

(3) the formed iron mud system can be self-circulated, no discharged solid waste exists, the iron mud resource is fully utilized, and the problem of secondary pollution of iron mud by a Fenton oxidation method is solved;

(4) the method can recycle the ferrous sulfate solution and the carbon powder, reduce the cost of raw materials and waste treatment, and has better economic value.

(5) The method provided by the invention has the advantages of simple equipment, convenience in operation and easiness in realization of industrialization.

Drawings

FIG. 1 is a nitrogen adsorption graph of carbon powder obtained in examples 1 to 5 of the present invention;

FIG. 2 is an adsorption isotherm diagram of 2-amino-4-methylbenzothiazole with carbon powder obtained in examples 1 to 5 of the present invention.

Detailed Description

Specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but it should be understood that the scope of the present invention is not limited to the specific embodiments. Test methods in which specific conditions are not specified in the following examples are generally carried out under conventional conditions or under conditions recommended by the respective manufacturers.

In the following specific examples, excessive iron powder is added into the filtrate obtained in S2, stirred for 1h, filtered to obtain a ferrous sulfate solution, and concentrated and reused in the process of oxidation treatment of organic wastewater by a Fenton method.

Example 1

A resource utilization method of iron mud generated by organic wastewater treatment by a Fenton method specifically comprises the following steps:

s1, breaking residual blocky chemical iron mud after the organic wastewater is subjected to Fenton method and activated carbon adsorption treatment into small blocks, drying the small blocks in a 50 ℃ blast drying oven for 24 hours, and then grinding the small blocks into powder to obtain primary iron mud;

s2, adding 200mL of 25% sulfuric acid into 5g of the primary iron mud obtained in the step S1, stirring for 1.5h at 70 ℃ on an electromagnetic stirrer, then carrying out suction filtration by using a circulating water type multipurpose vacuum pump, and collecting filtrate and filter residues;

s3, drying the filter residue obtained in the step S2 at 50 ℃ for 24 hours, then putting the filter residue into a ceramic crucible, pyrolyzing the filter residue in a muffle furnace at 200 ℃ for 1 hour in a nitrogen atmosphere, and naturally cooling the filter residue to room temperature to obtain black carbon powder TNC-200;

and S4, recycling the black carbon powder TNC-200 obtained in the S3 in the process of treating the organic wastewater by using activated carbon adsorption to form resource utilization of the iron mud.

Example 2

A resource utilization method of iron mud generated by organic wastewater treatment by a Fenton method is the same as that in example 1, and only the differences are that the pyrolysis temperature used in S3 is 400 ℃, and dark brown powder TNC-400 is obtained.

Example 3

A resource utilization method of iron mud generated by organic wastewater treatment by a Fenton method is the same as that in example 1, and only the difference is that the pyrolysis temperature used in S3 is 500 ℃, and dark brown powder TNC-500 is obtained.

Example 4

A resource utilization method of iron mud generated by organic wastewater treatment by a Fenton method is the same as that in example 1, and only the difference is that the pyrolysis temperature used in S3 is 600 ℃, and dark brown powder TNC-600 is obtained.

Example 5

A resource utilization method of iron mud generated by organic wastewater treatment by a Fenton method is the same as that in example 1, and only the difference is that the pyrolysis temperature used in S3 is 800 ℃, and dark brown powder TNC-800 is obtained.

Comparative example 1

A resource utilization method of iron mud generated by organic wastewater treatment through a Fenton method is the same as that in example 1, and is different in that primary iron mud obtained from S1 is directly subjected to S3 pyrolysis without being treated with S2, and dark brown powder TN-200 is obtained.

Comparative example 2

A resource utilization method of iron mud generated by organic wastewater treatment through a Fenton method is the same as that in example 2, and is different in that primary iron mud obtained from S1 is directly subjected to S3 pyrolysis without being treated with S2, and brown powder TN-400 is obtained.

Comparative example 3

A resource utilization method of iron mud generated by organic wastewater treatment by a Fenton method is the same as that in example 3, and only the difference is that primary iron mud obtained from S1 is directly subjected to S3 pyrolysis without being treated by S2, and brick red powder TN-500 is obtained.

Comparative example 4

A resource utilization method of iron mud generated by organic wastewater treatment through a Fenton method is the same as that in example 4, and the difference is that primary iron mud obtained from S1 is directly subjected to S3 pyrolysis without being treated with S2, and brick red powder TN-600 is obtained.

Comparative example 5

A resource utilization method of iron mud generated by organic wastewater treatment through a Fenton method is the same as that in example 5, and is different in that primary iron mud obtained from S1 is directly subjected to S3 pyrolysis without being treated with S2, and dark brown powder TN-800 is obtained.

In the specific embodiment of the present invention, the elemental analysis was performed using a Vario MACRO CUBE model elemental analyzer, and the pore size was measured using a quanorasorb SI model fully automatic multi-station specific surface and porosity analyzer.

First, water content measurement

And (3) drying the iron mud sample to determine the water content, wherein the water content is reduced firstly quickly and then slowly in the drying process, the water content tends to be gentle in 35 to 65 hours, and the iron mud quality is stable in 65 hours. The water content of the iron mud sample was calculated to be 41.14%.

Second, elemental analysis

The results of elemental analysis of the carbon powders obtained in examples 1 to 5 of the present invention and comparative examples 1 to 5 are shown in table 1, and it can be seen from table 1 that the amount of N, C in the carbon powders obtained in examples 1 to 5 is increased as compared with comparative examples 1 to 5, because the organic matter in the iron sludge reacts with the acid, the carbon powders form a substance similar to activated carbon, and the amount of N, C, H in the carbon powders obtained in examples 1 and 2 is the largest. In addition, TN-800 and TNC-200 have large carbon-to-hydrogen ratio and consume less oxygen than other samples.

TABLE 1 elemental analysis results of carbon powders obtained in examples 1 to 5 and comparative examples 1 to 5

Third, specific surface area and pore size analysis

FIG. 1 is a nitrogen adsorption graph of carbon powders obtained in examples 1 to 5 of the present invention, and it can be seen from FIG. 1 that TNC-400 obtained in example 2 hasHighest N₂The adsorption capacity, namely the nitrogen adsorption capacity of the TNC-400 is almost three times that of the TNC-400, which also indicates that the TNC-400 has a developed pore structure, and meanwhile, the adsorption effect of the TNC-400 is obviously increased when the relative pressure is in the range of 0.5 to 1.0, which indicates that the most main pore structure form of the TNC-400 is micropores, and indicates that the TNC-400 can be used as an adsorbent.

TABLE 2 results of specific surface area and pore diameter characteristics of the carbon powders obtained in examples 1 to 5 and comparative examples 1 to 5

Table 2 shows the results of the specific surface area and pore diameter characteristics of the carbon powders obtained in examples 1 to 5 of the present invention and comparative examples 1 to 5. As can be seen from Table 2, the specific surface area of the regenerated iron sludge (TN-200 to TN-800) produced by the comparative examples 1 to 5 is first reduced and then increased with the increase of the pyrolysis temperature, while the specific surface area of the regenerated iron sludge (TNC-200 to TNC-800) produced by the examples 1 to 5 of the present invention is first increased and then reduced with the increase of the pyrolysis temperature, which indicates that the specific surface area of the carbon powder is independent of the temperature. Wherein the carbon powder TNC-400 obtained in example 2 had the largest specific surface area, pore area and pore volume of 562.58m²/g、456.73m²G and 0.19cm³In terms of/g, and the average pore diameter was the smallest, 2.28nm, in accordance with the results of FIG. 1. From the above results, it is understood that the carbon powder TNC-400 obtained in example 2 has micropores with a large area and a large volume and a large specific surface area.

Fourth, study of adsorption experiment

Weighing 5 parts of each of carbon powder TNC-200, TNC-400, TNC-500, TNC-600 and TNC-800 obtained in examples 1-5 of the invention, placing 0.100g of each part in a conical flask, sequentially adding 100mL of 2-amino-4-methylbenzothiazole solution with initial concentrations of 100mg/L, 200mg/L, 300mg/L, 400mg/L and 500mg/L, oscillating for 24 hours at 303K in a constant temperature oscillator at the rotating speed of 130r/min, sucking 1.5mL of oscillated solution by using a 2.5mL needle cylinder after oscillation is finished, transferring the solution into a liquid chromatography sample bottle, analyzing the equilibrium concentration by adopting HPLC, and calculating the equilibrium adsorption capacity of each resin.

FIG. 2 shows the adsorption isotherms of TNC-200, TNC-400, TNC-500, TNC-600 and TNC-800 on 2-amino-4-methylbenzothiazole in an aqueous solution at 303K, respectively, and it can be seen from FIG. 2 that TNC-400 at 303K has the best adsorption effect on 2-amino-4-methylbenzothiazole in an aqueous solution.

In conclusion, the carbon powder TNC-400 treated by the method provided by the embodiment 2 of the invention has the best adsorption effect on the 2-amino-4-methylbenzothiazole in the wastewater, and the regenerated iron mud obtained by the other embodiments can also adsorb the 2-amino-4-methylbenzothiazole in the wastewater, but the adsorption effect is slightly worse.

It should be noted that when the following claims refer to numerical ranges, it should be understood that both ends of each numerical range and any value between the two ends can be selected, and since the steps and methods used are the same as those of the embodiments, the preferred embodiments and effects thereof are described in the present invention for the sake of avoiding redundancy, but once the basic inventive concept is known, those skilled in the art may make other changes and modifications to the embodiments. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims (2)

1. A resource utilization method of iron mud generated by organic wastewater treatment by a Fenton method is characterized by comprising the following steps:

s1, breaking the residual chemical iron mud after the organic wastewater is subjected to Fenton method and activated carbon adsorption treatment into blocks, drying at 40-60 ℃ for 12-24 h, and then grinding into powder to obtain primary iron mud;

s2, adding dilute sulfuric acid into the primary iron mud obtained in the step S1, stirring for 1-2 hours at the temperature of 65-75 ℃, then performing suction filtration, and collecting filtrate and filter residues, wherein the mass ratio of the primary iron mud to the dilute sulfuric acid is 1: 1-1.5;

reducing the filtrate by using iron powder to obtain a ferrous sulfate solution, and recycling the ferrous sulfate solution after concentration in the process of oxidizing and treating organic wastewater by using a Fenton method;

s3, drying the filter residue obtained in the step S2 at 40-60 ℃ for 12-24 hours, then putting the filter residue into a ceramic crucible, pyrolyzing the filter residue for 1 hour at 400 ℃ in a nitrogen atmosphere, and naturally cooling the filter residue to room temperature to obtain carbon powder;

and S4, recycling the carbon powder obtained in the step S3 in the process of treating the organic wastewater by activated carbon adsorption to form resource utilization of the iron mud.

2. The method for recycling iron sludge produced by treating organic wastewater by the Fenton method according to claim 1, wherein in S2, the mass fraction of the dilute sulfuric acid is 25%.

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