AU2021105316A4

AU2021105316A4 - Preparation Method and Application of Novel Quinone Mediator Material

Info

Publication number: AU2021105316A4
Application number: AU2021105316A
Authority: AU
Inventors: Jie Ding; Hanjun Sun; Guangyuan WANG; Guojun Xie; Shanshan Yang
Original assignee: Harbin Institute of Technology
Current assignee: Harbin Institute of Technology
Priority date: 2021-08-11
Filing date: 2021-08-11
Publication date: 2021-10-07
Anticipated expiration: 2029-08-11

Abstract

The invention discloses a preparation method and application of a novel quinone mediator material. According to the invention, the waste sludge-based biochar of a sewage plant is used as a carrier, and anthraquinone compounds are connected to the surface of the biochar in a chemical bonding mode. Therefore, the loaded anthraquinone compounds are not easy to fall off from the surface of the biochar, and have high stability and can be recycled. The application of the loaded material in an anaerobic bioreactor can catalyze the anaerobic biotransformation of pollutants and improve the treatment efficiency. The preparation method provided by the invention is simple in process, strong in adaptability. It is capable of large-scale production, capable of realizing resource utilization of excess sludge. It has high efficiency in treating printing and dyeing wastewater.

Description

Preparation Method and Application of Novel Quinone Mediator Material

TECHNICAL FIELD

The invention belongs to the field of sewage treatment and sewage treatment materials, and

particularly relates to a preparation method and application of a novel quinone mediator

material.

BACKGROUND

With the development of economy, printing and dyeing industry plays a very important

role in the world economy and daily life. At the same time, however, it produces a large

amount of colored printing and dyeing wastewater, and the discharge of printing and dyeing

wastewater poses a great threat to the water environment. Azo dye is a kind of dye. Because

its molecule contains azo group -N=N-chromophore, it is called azo dye. Azo dye ranks

first among all kinds of dyes with wide chromatogram, uniform variety, large output and

wide application. If the wastewater containing reactive azo dye is effectively treated, it

means that most problems of dye wastewater treatment will be solved.

Biological method is the most widely used method to treat printing and dyeing wastewater

at present, especially the anaerobic+aerobic process is the most effective method to treat

this kind of wastewater. The low redox potential, complex structure and space obstruction

of dye molecules make the reduction and bond breaking reaction become the speed-limiting

step in the whole mineralization process of azo dyes. Therefore, the transfer of azo dyes

from the initial electron donor (co-metabolite) to the final electron acceptor is usually the

control step of anaerobic reduction of azo dyes.

Some compounds containing quinonyl can effectively accelerate the biological reduction

and transformation process of azo dyes. However, the redox mediator containing quinonyl

has strong water solubility, and it is easy to be discharged with water when directly added

into the reaction system, thus bringing secondary pollution and high cost.

SUMMARY

In view of the above situation, the present invention provides a preparation method and

application of a novel quinone mediator material, aiming at loading a soluble quinone

mediator into an insoluble carrier material to prepare a new quinone mediator material. The

insoluble carrier material is biochar prepared from excess sludge. This method can provide

a new way for recycling excess sludge. This method is also used in the treatment

technology of azo dye wastewater to improve the anaerobic biological treatment effect of

azo dye, thus can avoid the loss of quinone mediator and reuse it repeatedly.

In order to achieve the above technical purpose, the present invention provides the

following technical scheme.

A preparation method of a quinone mediator material comprises the following steps.

The pretreated sludge-based biochar is immersed in a hydrochloric acid solution containing

zinc chloride for modification. It is taken out after standing for reaction. Then it is washed

to neutrality, and dried to obtain modified sludge-based biochar.

The modified sludge-based biochar is added to the anthraquinone compound solution for

reaction. The surface of the modified sludge-based biochar is washed and dried to obtain

the quinone mediator material.

Further, the sludge-based biochar is prepared by drying the excess sludge after gravity

concentration, pyrolyzing at high temperature under the condition of isolating air, and then

cooling, grinding and sieving.

Further, the excess sludge is gravity concentrated at 4°C and dried at 40-60°C.

Further, the high-temperature pyrolysis conditions are as follows. Putting the sludge-based

biochar into a tubular furnace, and pyrolyzing at a temperature of 350-950°C for 60-180

min under the atmosphere of carbon dioxide and nitrogen gas.

Further, the cooled sludge-based biochar is ground to pass through a 1-2 mm sieve.

Further, the pretreatment is to use deionized water to wash the surface of the sludge-based

biochar to neutrality and then dry it.

Furthermore, the content of zinc chloride in the hydrochloric acid solution is 250 g/L, and

the mass fraction of the hydrochloric acid is 37%.

Furthermore, the modification conditions are as follows. The temperature is 25-35°C, and

the time is 36-48 h.

Furthermore, the anthraquinone compound is anthraquinone 2 sodium sulfonate (AQS),

and its solution concentration is 1000 mg/L . The anthraquinone compound can also be

benzoquinone, anthraquinone and naphthoquinone compounds containing sulfonate

groups.

The reaction is carried out in a shaking table at a temperature of 25-35°C, a rotating speed

of 80-120 rpm and a time of 48 h. The drying temperature is 40-60°C.

The invention also discloses an application of the quinone mediator material obtained by

the preparation method in dye wastewater treatment technology.

Compared with the prior art, the invention has the beneficial effects as follows.

The invention provides a preparation method of a novel quinone mediator material. The

method adopts excess sludge as a substrate to prepare sludge biochar, and modifies the

surface of the sludge biochar. The method makes the sludge biochar have higher surface

loading performance, more developed void structure, and more surface functional groups.

Therefore, the method provides an effective material for biological treatment of azo dye

pollution. For sewage treatment facilities, the disposal cost of excess sludge accounts for

about 20-30% of its operating cost. Therefore, preparing the excess sludge into biochar

material to improve the operation and treatment effect of sewage plants is an ideal disposal

method of energy internal circulation.

According to the invention, the efficiency of loading anthraquinone compounds on the

sludge-based biochar is improved by adopting a pretreatment mode of hydrochloric acid

solution containing zinc chloride, so that the strong biocatalytic efficiency of the biochar

is realized. The main action mechanism is that chlorine atoms replace hydroxyl functional

groups (-OH) on the surface of the biochar to form chlorine substituents. Then sulfonic

acid groups in anthraquinone 2 sodium sulfonate are combined with chlorine substituents

to form covalent structures with high stability. After being fixed on biochar, anthraquinone

2 sodium sulfonate can effectively avoid secondary pollution, and can be recycled. It has

excellent economy, environmental friendliness and excellent mechanical properties. It can be used as a filler in a bioreactor to enhance the anaerobic biological treatment efficiency of azo dyes.

The preparation method provided by the invention is simple in process, strong in

adaptability. It is capable of large-scale production, capable of realizing resource utilization

of excess sludge. It has high efficiency in treating printing and dyeing wastewater.

BRIEF DESCRIPTION OF THE FIGURES

In order to explain the embodiments of the present invention or the technical scheme in the

prior art more clearly, the figures needed in the embodiments will be briefly introduced

below. Obviously, the figures in the following description are only some embodiments of

the present invention, and for ordinary technicians in the field, other figures can be obtained

according to these figures without paying creative labor.

Figure 1 A Fourier transform infrared spectrum of modified sludge-based biochar and

quinone mediator material prepared in Embodiment 1

Figure 2 A SEM image of the surface of modified sludge-based biochar and quinone

mediator material prepared in Embodiment 1

Figure 3 An x-ray diffraction pattern of modified sludge-based biochar and quinone

mediator material prepared in Embodiment 1

Figure 4 An electron transfer capability measurement chart of modified sludge-based

biochar and quinone mediator material prepared in Embodiment 1

Figure 5 The application of quinone mediator material prepared in Embodiment 1 in

anaerobic biological treatment of reactive red 2 in a bioreactor (AnSBR)

Figure 6 The application of quinone mediator material prepared in Embodiment 1 in

anaerobic biological treatment of reactive red 2 dye in upflow fixed bed biofilm reactor

(UAFB). DESCRIPTION OF THE INVENTION

Various exemplary embodiments of the present invention will now be described in detail,

which should not be regarded as a limitation of the present invention, but rather as a more

detailed description of certain aspects, characteristics and embodiments of the present

invention.

It should be understood that the terms described in the present invention are only for

describing specific embodiments, and are not intended to limit the present invention. In

addition, as for the numerical range in the present invention, it should be understood that

every intermediate value between the upper limit and the lower limit of the range is also

specifically disclosed. Intermediate values within any stated value or stated range and every

smaller range between any other stated value or intermediate values within the stated range

are also included in the present invention. The upper and lower limits of these smaller

ranges can be independently included or excluded from the range.

Unless otherwise stated, all technical and scientific terms used herein have the same

meanings as commonly understood by those skilled in the art to which the present invention

relates. Although the present invention only describes preferred methods and materials,

any methods and materials similar or equivalent to those described herein may be used in

the practice or testing of the present invention. All documents mentioned in this

specification are incorporated by reference to disclose and describe methods and/or materials related to the documents. In case of conflict with any incorporated documents, the contents of this specification shall prevail.

Without departing from the scope or spirit of the invention, it is obvious to those skilled in

the art that many modifications and changes can be made to the specific embodiments of

the specification of the invention. Other embodiments derived from the description of the

present invention will be apparent to the skilled person. The specification and embodiments

of this application are only exemplary.

As used herein, "including", "comprising", "having", "containing", etc. are all open terms,

which means including but not limited to.

Embodiment 1

The excess sludge was gravity concentrated at 4°C for 24 h after being retrieved. The

concentrated excess sludge was dried at 60°C. After being dried, 20g of dry sludge was

weighed and placed in a crucible boat, and then the crucible boat was put into a pyrolysis

furnace for pyrolysis treatment. The ambient gas wasC02, the flow rate was 0.8 L/min, the

heating rate was 5°C/min, and the temperature was 550°C. After cooling to room

temperature, the sludge was ground and screened by 1-2 mm to obtain sludge-based

biochar.

The prepared sludge-based biochar was washed to neutrality by deionized water and then

dried at 60°C for 24 h. Weighed 5g of sludge-based biochar and soaked it in 50 mL of

hydrochloric acid with mass fraction of 37%. The content of zinc chloride in hydrochloric

acid solution was 250 g/L, the reaction conditions were 30°C and standing for 48 h. After

the reaction, the sludge-based biochar was separated from the hydrochloric acid solution containing zinc chloride. The sludge-based biochar was repeatedly washed to neutrality with deionized water, and dried at 60°C to obtain modified sludge-based biochar.

The modified sludge-based biochar was put into 1000 mg/L anthraquinone 2 sodium

sulfonate solution. The reaction was carried out in a shaking table with conditions of 30°C,

120 rpm and 48 h. After the reaction, the surface was washed with deionized water to

neutrality, and dried at 60°C to obtain quinone mediator material.

Figure 1 is a Fourier transform infrared spectrum of modified sludge-based biochar and

quinone mediator material prepared in this embodiment. It can be seen from the figure that

the modified sludge-based biochar and quinone mediator material all have characteristic

peaks at 3420-3440 cm-1, 1700-1750 cm-1, 1630-1650 cm-1 and 1420-1440 cm-1,

representing oxygen-containing functional groups (carboxyl, aldehyde, ketone and

quinonyl), respectively. The characteristic peak of sulfonic acid group (-SO 3 ) in

anthraquinone 2 sodium sulfonate is at 1215 cm- 1, indicating that anthraquinone 2 sodium

sulfonate has been successfully loaded on the surface of biochar.

Figure 2 is a scanning electron micrograph of the surface of modified sludge-based biochar

and quinone mediator material prepared in this embodiment. It can be seen from the figure

that the surface of modified sludge-based biochar is rough, and the surface morphology

presents granular structure. After loading quinone mediator, the granular structure on the

surface of the material becomes smaller, the surface becomes coarser, and pore structure

appears, indicating that a more favorable surface structure for loading quinone mediator is

provided.

Figure 3 is an x-ray diffraction pattern of modified sludge-based biochar and quinone

mediator material prepared in this embodiment. It can be seen from the figure that there

are vibration peaks of quinone (531.2 eV), carbonyl (532.5 eV), hydroxyl (533.7 eV) and

carboxyl (534.3-535.4 eV). After loading anthraquinone, the contents of carboxyl,

hydroxyl, carbon and quinonyl on the surface of quinonyl materials are 3.35%, 2.73%,

47.21% and 46.70%, respectively. The content of corresponding groups on the surface of

modified sludge-based biochar is 3.90%, 27.54%, 43.98% and 24.58% respectively. After

loading anthraquinone 2 sodium sulfonate, the quinonyl and carbonyl content on the

surface of the modified sludge-based biochar increased by 47.34 and 6.83%, respectively,

while the hydroxyl content decreased by 90.05% after loading. This indicates that sodium

anthraquinone 2 sodium sulfonate is loaded on the surface of modified sludge-based

biochar and replaces the original hydroxyl structure.

Figure 4 is the measurement of electron transfer ability of biochar and quinone mediator

material prepared in this embodiment. It can be seen from the figure that before loading

anthraquinone 2 sodium sulfonate, the electron gain ability of biochar is 0.528 and 0.972

mmol e- g-1 , and the electron donating capacity is 0.269 and 0.760 mmol e- g-1 , respectively.

After loading anthraquinone 2 sodium sulfonate, the electron gain ability and electron

donating ability are increased by 45.68 and 64.61%, respectively. The electron gain and

loss ability of biochar before and after loading is the absolute sum of the electron gain

ability and electron loss ability, which is 0.937 and 2.114, respectively. The electron gain

and loss ability is improved by 55.68%, indicating that quinone mediator material has good

electron transfer ability.

Test example 1

Experiment of treatment effect of biochar-based anthraquinone (BC-AQS) mediator on

reactive red 2 dye wastewater. The quinone mediator material prepared in Embodiment 1

was put into an anaerobic sequencing batch bioreactor (AnSBR) (as shown in Figure 5).

The middle and lower parts of the reactor are equipped with stirring paddles. The quinone

mediator material was added into the reactor and naturally settled to the bottom. The

addition concentration was 20 g/L, and the particle size was 1-2 mm. Anaerobic flocculent

sludge (MLSS is 4000 mg/L) which has been domesticated in advance was added into the

reaction system. The lower part of the side of the reactor is equipped with a water outlet.

The upper side of the reactor is provided with a water inlet, and the top of the reactor is

provided with a vent and a sampling port. The sampling port extends below the reaction

liquid level to realize the water sealing function. The hydraulic retention time of the reactor

was 24 h, drainage was 10 min, water inflow was 10 min, sedimentation was 30 min, the

rest of the time was mixing and stirring in the reaction system, the stirring speed was 30

rpm, and the temperature was controlled at 30°C. The quinone mediator material can

naturally settle into the reaction system, and there is no requirement for AnSBR structure.

This application method has a wide application prospect in upgrading sewage treatment

facilities. The experimental results of biodegradation of reactive red 2 during the actual

operation of the reactor show that when the influent concentration of reactive red 2 was

100-400 mg/L, the average decolorization rates of the materials with quinone mediator and

without quinone mediator in the reaction system were 81-92% and 22-39%, respectively.

This indicates that bio-carbon based quinone mediator material can enhance the biological

treatment of azo dyes and significantly accelerate the extracellular electron transfer process

of microorganisms on its surface.

Test example 2

The quinone mediator material prepared in Embodiment 1 was put into an upflow fixed

bed biofilm (UAFB) reactor for biological treatment experiment of reactive red 2 dye (as

shown in Figure 6). The applied UAFB reactor is provided with a water inlet at the bottom,

an air outlet at the upper part, a water outlet at the top side, an internal reflux port at the

upper side and sampling ports. In order to prevent the bottom of the filler layer from being

blocked, a cobblestone cushion layer is arranged at the bottom of the filler layer. The height

of the cushion layer accounts for about 10% of the total cushion layer. The upper part of

cobblestone is a quinone mediator filler layer, and the side part of the packing layer is

provided with three sampling ports of solid filler, namely upper, middle and lower. The

sampling ports extend to the outside. Isolation columns are arranged between the outermost

parts of the sampling ports and the filler layer to prevent the filler from entering the

sampling tube to cause short circuit in the treatment area and affect the evaluation of the

actual performance of the quinone mediator filler. ORP electrode is arranged on the upper

part of filler layer, and liquid sampling ports are arranged on the side of reactor. The particle

size of quinone mediator in the filler layer was 2-3mm. After the quinone mediator was

filled into the reactor, the filler was inoculated by beating mud hanging method to speed

up the formation time of biofilm. The anaerobic sludge was anaerobic flocculent sludge

domesticated in advance. After 7 days of domestication, the sludge was completely

discharged and the biofilm domestication was started. The reactor adopted internal

circulation to increase the ascending flow rate to 1 m/L, and after 15 days of cultivation,

the biofilm was formed. The concentration of reactive red 2 in influent water was 100-400

mg/L. After long-term operation, the removal rate of reactive red 2 by the reaction system could reach 83-95%. The reaction system has a good decolorization effect on reactive red

2.

To sum up, after the biochar material in the present invention is pretreated by the

hydrochloric acid zinc chloride solution, the loading rate of the quinone mediator is

increased, thereby accelerating the treatment of azo dyes in the anaerobic biological

reaction system. Moreover, the surface of the material is easy to form biofilm content while

promoting the treatment of pollutants.

Embodiment 2

concentrated excess sludge was dried at 40°C. After being dried, 20g of dry sludge was

furnace for pyrolysis treatment. The ambient gas was N2, the flow rate was 0.8 L/min, the

heating rate was 5°C/min, and the temperature was 950°C. After cooling to room

biochar.

dried at 40°C for 24 h. Weighed 5g of sludge-based biochar and soaked it in 50 mL of

the reaction, the sludge-based biochar was separated from the hydrochloric acid solution

containing zinc chloride. The sludge-based biochar was repeatedly washed to neutrality

with deionized water, and dried at 40°C to obtain modified sludge-based biochar.

The modified sludge-based biochar was put into 1000 mg/L naphthoquinone (2- hydroxyl

-1,4- naphthoquinone) solution, and the reaction was carried out in a shaking table with

conditions of 35°C, 120 rpm and 48 h. After the reaction, the surface was washed with

deionized water to neutrality, and dried at 40°C to obtain quinone mediator material.

The removal rate of reactive red 2 in UAFB reactor used by this quinone mediator material

was 93%.

Embodiment 3

concentrated excess sludge was dried at 50°C. After being dried, 20g of dry sludge was

heating rate was 5°C/min, and the temperature was 300°C. After cooling to room

biochar.

dried at 50°C for 24 h. Weighed 5g of sludge-based biochar and soaked it in 50 mL of

with deionized water, and dried at 50°C to obtain modified sludge-based biochar.

The modified sludge-based biochar was put into 1000 mg/L anthraquinone solution, and

the reaction was carried out in a shaking table with conditions of 25°C, 80 rpm and 48 h.

After the reaction, the surface was washed with deionized water to neutrality, and dried at

°C to obtain quinone mediator material.

was 84%.

Comparative example 1

Same as Embodiment 1, except that the modified sludge-based biochar was replaced by

sludge-based biochar. The prepared quinone mediator material was put into an upflow

fixed bed biofilm reactor (UAFB) for biological treatment experiment of reactive red 2

dye. It was found that the removal rate of reactive red 2 was 63%, and the removal rate

decreased significantly.

Comparative example 2

Compared with Embodiment 1, the difference lied in that the solution of anthraquinone 2

sodium sulfonate was directly added to the upflow fixed bed biofilm reactor (UAFB) for

biological treatment experiment of reactive red 2 dye. The results showed that the removal

rate of reactive red 2 was 98%, but anthraquinone 2 sodium sulfonate flowed out with

water, causing secondary pollution.

Comparative example 3

Compared with Embodiment 1, the difference is that the biological treatment experiment

of reactive red 2 dye was carried out in an upflow fixed bed biofilm reactor (UAFB) without adding quinone mediator material. The results showed that the removal rate of reactive red

2 was 33%, and the removal rate dropped obviously.

The above is only a preferred embodiment of the present invention, and is not intended to

limit the present invention. Any modifications, equivalent substitutions and improvements

made within the spirit and principles of the present invention shall be included in the scope

of protection of the present invention.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A preparation method of quinone mediator material, characterized by comprising the

following steps:

zinc chloride for modification; then it is washed to neutrality, and dried to obtain modified

sludge-based biochar;

reaction; then it is washed and dried to obtain the quinone mediator material.

2. The preparation method according to Claim 1, characterized in that the sludge-based

biochar is prepared by drying the excess sludge after gravity concentration, pyrolyzing at

high temperature under the condition of isolating air, and then cooling, grinding and

sieving.

3. The preparation method according to Claim 2, characterized in that the excess sludge is

gravity concentrated at 4°C and dried at 40-60°C.

4. The preparation method according to Claim 2, characterized in that the high-temperature

pyrolysis conditions are carbon dioxide gas atmosphere, temperature of 300-950°C, and

time of 60-180 min.

5. The preparation method according to Claim 2, characterized in that the cooled sludge

based biochar is ground to pass through a 1-2 mm sieve.

6. The preparation method according to Claim 1, characterized in that the pretreatment is

washing to neutrality and then drying.

7. The preparation method according to Claim 1, characterized in that the content of zinc

chloride in the hydrochloric acid solution is 250 g/L, and the mass fraction of the

hydrochloric acid is 37%.

8. The preparation method according to Claim 1, characterized in that the modification

conditions are temperature of 25-35°C. and time of 36-48 h.

9. The preparation method according to Claim 1, characterized in that the anthraquinone

compound is anthraquinone 2 sodium sulfonate; the reaction conditions are as follows: the

temperature is 25-35°C, the rotating speed is 80-120 rpm, and the time is 48 h.

10. Application of a quinone mediator material obtained by the preparation method

according to any one of Claims 1 to 9 in dye wastewater treatment technology.