AU2021104566A4

AU2021104566A4 - Preparation method of oily sludge-based adsorbing carbon materials for oily sewage disposal

Info

Publication number: AU2021104566A4
Application number: AU2021104566A
Authority: AU
Inventors: Mingming DU; Haijie HU; Linxin QIN; Chengtun QU; Bo Yang; Tao Yu
Original assignee: Xian Shiyou University
Current assignee: Xian Shiyou University
Priority date: 2021-07-26
Filing date: 2021-07-26
Publication date: 2021-09-23
Anticipated expiration: 2029-07-26

Abstract

OF THE DISCLOSURE The present disclosure provides a preparation method of oily sludge-based adsorbing carbon materials for oily sewage disposal, in which oily sludge that is produced in oil exploitation and refining processes and has been treated through reduction is used as the raw material and mixed with nutshells and seeds to improve the carbon content of oily sludge and the porosity of carbides, ethanolamine is used as the chemical pore-enlarging agent and industrial alkali waste is used as the activating agent, so as to prepare oily sludge-based adsorbing carbon materials by the combination of a chemical pore-enlarging method and an activation method. The present disclosure has the advantages of low reaction temperature, simple process, and a reduced preparation cost, there are a high proportion of mesopores in the resulting carbon materials, which are suitable for adsorption of petroleum substances in oily sewage, and can effectively remove suspended oil and emulsified oil in the oily sewage, enabling the in-situ utilization of oily sludge-based adsorbing carbon materials, thus realizing the stabilization, harmless and recycling treatment of the oily sludge. 17910824_1 (GHMatters) P116825.AU

Description

PREPARATION METHOD OF OILY SLUDGE-BASED ADSORBING CARBON MATERIALS FOR OILY SEWAGE DISPOSAL TECHNICAL FIELD

[01] The present disclosure belongs to the technical field of environmental

protection, and specifically relates to a preparation method of oily sludge-based

adsorbing carbon materials for oily sewage disposal.

BACKGROUNDART

[02] Oily sludge is the major waste produced in oil and petrochemical enterprises,

which has become one of the hot spots of pollution control in oil and petrochemical

enterprises because it contains a large amount of petroleum hydrocarbons, heavy metals,

pathogenic bacteria and the like. Common disposal methods of oily sludge include

incineration, pyrolysis and biological treatment, etc. Oily sludge contains a large

amount of petroleum hydrocarbons, so it is a good raw material for the preparation of

activated carbon due to its high carbon content. However, the preparation of carbon

materials from oily sludge is limited by the production region, production process and

oil content of the oily sludge; if the carbon materials prepared from oily sludge are

applied in removing the pollutants produced in the oil exploitation and processing (e.g.,

being applied in oily sewage disposal), the transportation and disposal costs can be

reduced to some extent, thus having good environmental and economic benefits.

[03] At present, the research on the preparation of adsorbing carbon materials from

oily sludge is mainly focus on improving the specific surface area of the prepared

carbon materials. During the preparation, zinc chloride, potassium hydroxide and

concentrated sulfuric acid are employed as the activating agents. During the activation

of the above substances, oily sludge is transformed into carbon materials with abundant

micropores through a series of crosslinking, polycondensation and elution of chemicals.

1 17910824_1(GHMtters) P116825.AU

However, there are some limitations in the practical application of carbon materials with

abundant micropores, for example, pollutants of higher molecular weight are difficult to

remove. Therefore, the carbon materials with abundant micropores should be

pore-enlarged so as to improve the porosity and control the pore size distribution, which

is conducive to improving the removal rate of particular pollutants. Currently, the main

way to improve the porosity of carbon materials is to conduct pore-enlarging on the

existing activated carbon under high pressure, high temperature and in the case of

injecting gas, which belongs to the scope of physical pore-enlarging, and its main

advantages are in that the micropores of the activated carbon could be further enlarged,

and the injected gas can dredge the blocked pore channels. However, the pore-enlarging

process consumes much energy, and it proposes high requirement on the strength of the

equipment. Relative to physical pore-enlarging, chemical pore-enlarging requires low

temperature and has lower requirement on the strength of the equipment, so the energy

consumption in the pore-enlarging process can be greatly reduced, but the usage amount

of the pore-enlarging agent is relatively large.

SUMMARY

[04] In order to realize the harmless and recycling treatment of oily sludge, improve

the carbon content of oily sludge-based carbon materials and the porosity of carbides,

the present disclosure, with nutshells and seeds as pore-enlarging materials and

carburants, with ethanolamine as the chemical pore-enlarging agent, and with industrial

alkali waste as the activating agent, prepares oily sludge-based adsorbing carbon

materials that can remove suspended oil and emulsified oil in the oily sewage, thus

realizing the in-situ preparation and utilization of the oily sludge-based adsorbing

carbon materials.

[05] With respect to the above purpose, the present disclosure employs a technical

solution consisting of the following steps:

[06] 1. Oily sludge that is produced in oil exploitation and refining processes and

has been treated through reduction is dried to a moisture content less than 10%, to get

dry sludge; the dry sludge is mixed evenly with nutshells and seeds that have been 2 17910824_1 (GHMatters) P116825.AU crushed respectively, to get a mixture of raw materials, wherein the mass ratio of nutshells to seeds is 1-6:1, and the mass ratio of the total mass of nutshells and seeds to the dry sludge is 1:1-5.

[07] 2. The mixture of raw materials is mixed evenly with ethanolamine at a mass

ratio of 2-5:1, and thermostatically heated at 80-150°C for 3-6 h.

[08] 3. The heat treated products obtained from step 2 are impregnated in an

industrial alkali waste solution at normal temperature for 12-24 h, and upon the

completion of impregnation, they are oven-dried to a constant weight, to prepare

activated carbon precursors.

[09] 4. The activated carbon precursors are placed into a tubular furnace and

thermostatically carbonized at 510-590°C for 1.5-4 h, to prepare carbides.

[10] 5. The carbides are cooled to room temperature and soaked with hydrochloric

acid, and then washed with deionized water until neutral; the washed products are

oven-dried and ground to obtain the oily sludge-based adsorbing carbon materials.

[11] In the above step 1, the oily sludge that is produced in oil exploitation and

refining processes and has been treated through reduction has a moisture content of

%-65% and an oil content of 5%-10%.

[12] In the above step 1, it is preferable to crush the dry sludge and the nutshells,

seeds into grain sizes of 20-40 meshes respectively, then mix the dry sludge with the

nutshells and seeds evenly according to that the mass ratio of nutshells to seeds is 2-3:1

and the mass ratio of the total mass of nutshells and seeds to the dry sludge is 1:1-3, in

which the nutshells are any one or more of Badam shells, pistachio nut shells, walnut

shells, and cottonseed hulls, and the seeds are any one or more of cotton seeds, grape

seed, watermelon seeds, and passion fruit seeds.

[13] In the above step 2, it is preferable to mix the mixture of raw materials with

ethanolamine evenly at a mass ratio of 2.5-4:1, and heat them thermostatically at

100-120°C for 3.5-5 h.

[14] In the above step 3, it is preferable that the mass-to-volume ratio of the heat

treated products to the industrial alkali waste solution is 1 g:1.5-2.5 mL, the main alkali 3 17910824_1 (GHMatters) P116825.AU ingredients in the industrial alkali waste solution are sodium hydroxide and sodium carbonate, and the total mass concentration of sodium hydroxide and sodium carbonate is 30%-40%.

[15] In the above step 4, it is preferable to place the activated carbon precursors obtained from step 3 into the tubular furnace, in which nitrogen is employed as the

protective gas, the gas flow rate is 100-150 mLmin, and the temperature is raised to

530-570°C at a heating rate of 10-15°C/min, and then carbonize thermostatically for 2-3

h to prepare the carbides.

[16] In the above step 5, it is preferable to cool the carbides to room temperature and soak with hydrochloric acid at a mass concentration of 5%-10% for 20-30 min, then wash with deionized water until neutral; and the washed products are oven-dried and

ground into grain sizes of 60-80 meshes, to obtain the oily sludge-based adsorbing

carbon materials.

[17] The present disclosure has the following beneficial effects:

[181 1. The present disclosure employs oily sludge that is produced in oil exploitation and refining processes and has been treated through reduction as the raw

material and mixes it with nutshells and seeds to improve the carbon content of oily

sludge and the porosity of the carbides; and employs ethanolamine as the chemical pore-enlarging agent and utilizes industrial alkali waste as the activating agent so as to

prepare oily sludge-based adsorbing carbon materials by the combination of a chemical

pore-enlarging method and an activation method. Such a method transforms oily sludge

into adsorbing carbon materials of certain economic value, by which oily sludge is

recycled, thus realizing the stabilization, harmless and recycling treatment of the oily

sludge.

[19] 2. The present disclosure requires low reaction temperature, the process is simple, the surface of the carbon materials prepared from oily sludge as the raw material

is highly lipophilic, which can adsorb a large amount of petroleum substances, thus

having a good oil removal performance; By using nutshells with a certain porosity of

their own such as Badam shells and pistachio nut shells and ethanolamine as the 4 17910824_1 (GHMatters) P116825.AU pore-enlarging materials, and using seeds with high carbon content such as cotton seeds and grape seeds as the carburants, the porosity and pore size of the carbon materials can be improved; by using biomass as the pore-enlarging material, both the usage amount of the chemical pore-enlarging agent and the preparation cost of the carbon materials can be reduced; industrial alkali waste is used as the activating agent, which is cheap relative to commonly used activating agents such as zinc chloride and potassium hydroxide, thus greatly reducing the preparation cost of the carbon materials.

[20] 3. With regard to the oily sewage produced in oil exploitation and refining

processes, the present disclosure utilizes oily sludge to prepare carbon materials with a

high proportion of mesopores, which are suitable for adsorption of petroleum

substances in oily sewage, and can effectively remove suspended oil and emulsified oil

in the oily sewage; the experimental results showed that when the carbon materials

prepared in the present disclosure are added into oily sewage with an oil content of

1500-3200 mg/L at an adding quantity of 2 g/L, the oil content in the sewage can be

reduced to 500-800 mg/L. The present disclosure realizes the in-situ utilization of oily

sludge-based adsorbing carbon materials, so the carbon materials are cheaper to use and

more practical.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[21] The present disclosure will be further illustrated in detail in combination with

the following embodiments, but the protection scope of the present disclosure is not

limited to these embodiments.

[22] Embodiment 1

[23] 1. Oily sludge with a moisture content of 62.2% and an oil content of 8% that

is produced in oil exploitation and refining processes and has been treated through

reduction was dried to a moisture content of 9% and an oil content of 7.2%, to get dry

sludge; the dry sludge, Badam shells and cotton seeds were crushed into grain sizes of

-40 meshes respectively, then 5.0 g dry sludge particles, 3.5 g Badam shell particles,

and 1.5 g cotton seed particles were mixed evenly to get a mixture of raw materials.

5 17910824_1 (GHMatters) P116825.AU

[24] 2. The mixture of raw materials obtained from step 1 was mixed evenly with 4

g ethanolamine, and thermostatically heated at 80°C for 4 h.

[25] 3. At a solid-liquid ratio of 1 g:1.5 mL, the heat treated products obtained from

step 2 were added into an industrial alkali waste solution and impregnated at normal

temperature for 24 h, the total mass concentration of sodium hydroxide and sodium

carbonate in the used industrial alkali waste solution was 30%; and upon the completion

of impregnation, they were oven-dried at 105°C to a constant weight, to prepare

activated carbon precursors.

[26] 4. The activated carbon precursors obtained from step 3 were placed into the

tubular furnace, into which nitrogen was injected at a flow rate of 100 mL/min and the

temperature was raised to 530°C at 10°C/min, and carbonized thermostatically for 2 h,

and then cooled to room temperature under the protection of nitrogen to prepare

carbides.

[27] 5. The carbides obtained from step 4 were soaked with hydrochloric acid at a

mass concentration of 5% for 30 min, and then washed with deionized water until

neutral; the washed products were oven-dried at 80°C and ground into particle sizes of

-80 meshes, to obtain the oily sludge-based adsorbing carbon materials.

[28] Comparative embodiment 1

[29] Oily sludge with a moisture content of 62.2% and an oil content of 8% that is

produced in oil exploitation and refining processes and has been treated through

sludge. 10 g of the dry sludge was added into 15 mL of the industrial alkali waste

solution and impregnated at normal temperature for 24 h, the total mass concentration

of sodium hydroxide and sodium carbonate in the used industrial alkali waste solution

was 30%; and upon the completion of impregnation, they were oven-dried at 105°C to a

constant weight, to prepare activated carbon precursors. After then, carbonization and

post-treatment were performed following the methods in steps 4 and 5 of embodiment 1,

to obtain oily sludge-based adsorbing carbon materials.

[30] Comparative embodiment 2 6 17910824_1 (GHMatters) P116825.AU

[31] Oily sludge with a moisture content of 62.2% and an oil content of 8% that is

sludge. 10 g of the dry sludge was mixed evenly with 4 g ethanolamine, and

thermostatically heated at 80°C for 4 h. After then, activation, carbonization and

post-treatment were performed following the methods in steps 3, 4 and 5 of

embodiment 1, to obtain oily sludge-based adsorbing carbon materials.

[32] Embodiment 2

[33] 1. Oily sludge with a moisture content of 64.1% and an oil content of 6.7% that

reduction was dried to a moisture content of 8% and an oil content of 6.1%, to get dry

sludge; the dry sludge, Badam shells and grape seeds were crushed into grain sizes of

-40 meshes respectively, then 6.0 g dry sludge particles, 3.0 g Badam shell particles,

and 1.0 g grape seed particles were mixed evenly to get a mixture of raw materials.

[34] 2. The mixture of raw materials obtained from step 1 was mixed evenly with 3

g ethanolamine, and thermostatically heated at 100°C for 3 h.

[35] 3. At a solid-liquid ratio of 1 g:2.5 mL, the heat treated products obtained from

carbonate in the used industrial alkali waste solution was 35%; and upon the completion

activated carbon precursors.

[36] 4. The activated carbon precursors obtained from step 3 were placed into the

temperature was raised to 530°C at 10°C/min, and carbonized thermostatically for 2.5 h,

and then cooled to room temperature under the protection of nitrogen to prepare

carbides.

[37] 5. The carbides obtained from step 4 were soaked with hydrochloric acid at a

mass concentration of 5% for 30 min, and then washed with deionized water until 7 17910824_1 (GHMatters) P116825.AU neutral; the washed products were oven-dried at 80°C and ground into particle sizes of

-80 meshes, to obtain the oily sludge-based adsorbing carbon materials.

[38] Embodiment 3

[391 1. Oily sludge with a moisture content of 61.5% and an oil content of 9.8% that is produced in oil exploitation and refining processes and has been treated through

reduction was dried to a moisture content of 7.5% and an oil content of 8.9%, to get dry

sludge; the dry sludge, pistachio nut shells, cotton seeds, and watermelon seeds were

crushed into grain sizes of 20-40 meshes respectively, then 5.0 g dry sludge particles,

3.5 g pistachio nut shell particles, 0.75 g cotton seed particles and 0.75 g watermelon

seed particles were mixed evenly to get a mixture of raw materials.

[40] 2. The mixture of raw materials obtained from step 1 was mixed evenly with 3 g ethanolamine, and thermostatically heated at 120°C for 5 h.

[41] 3. At a solid-liquid ratio of 1 g:2 mL, the heat treated products obtained from step 2 were added into an industrial alkali waste solution and impregnated at normal

activated carbon precursors.

[42] 4. The activated carbon precursors obtained from step 3 were placed into the tubular furnace, into which nitrogen was injected at a flow rate of 100 mL/min and the

temperature was raised to 550°C at 10°C/min, and carbonized thermostatically for 3 h,

and then cooled to room temperature under the protection of nitrogen to prepare

carbides.

[43] 5. The carbides obtained from step 4 were soaked with hydrochloric acid at a mass concentration of 5% for 30 min, and then washed with deionized water until

-80 meshes, to obtain the oily sludge-based adsorbing carbon materials.

[44] Embodiment 4

[45] 1. Oily sludge with a moisture content of 62.4% and an oil content of 7.4% that 8 17910824_1 (GHMatters) P116825.AU is produced in oil exploitation and refining processes and has been treated through reduction was dried to a moisture content of 8.8% and an oil content of 6.8%, to get dry sludge; the dry sludge, pistachio nut shells, cotton seeds, and grape seeds were crushed into grain sizes of 20-40 meshes respectively, then 6.0 g dry sludge particles, 3 g pistachio nut shell particles, 0.6 g cotton seed particles and 0.4 g grape seed particles were mixed evenly to get a mixture of raw materials.

[46] 2. The mixture of raw materials obtained from step 1 was mixed evenly with 3.5 g ethanolamine, and thermostatically heated at 150°C for 5 h.

[47] 3. At a solid-liquid ratio of 1 g:2 mL, the heat treated products obtained from step 2 were added into an industrial alkali waste solution and impregnated at normal temperature for 24 h, the total mass concentration of sodium hydroxide and sodium

carbonate in the used industrial alkali waste solution was 38%; and upon the completion

activated carbon precursors.

[48] 4. The activated carbon precursors obtained from step 3 were placed into the tubular furnace, into which nitrogen was injected at a flow rate of 100 mL/min and the

temperature was raised to 570°C at 10°C/min, and carbonized thermostatically for 3 h,

and then cooled to room temperature under the protection of nitrogen to prepare carbides.

[49] 5. The carbides obtained from step 4 were soaked with hydrochloric acid at a mass concentration of 5% for 30 min, and then washed with deionized water until

-80 meshes, to obtain the oily sludge-based adsorbing carbon materials.

[50] The inventors have analyzed the physicochemical data, including specific surface area and pore structure, of the oily sludge-based adsorbing carbon materials

prepared in the above embodiment 1 and comparative embodiments 1 and 2, with the

results shown in Table 1 below.

[51] Table 1 Pore structure data analysis of different adsorbing carbon materials

9 17910824_1 (GHMatters) P116825.AU

[521

Samples Specific Total pore Pore volume of Proportion of

surface area volume (cm 3/g) mesopores mesopores(%)

(m 2/g) (cm 3/g)

Comparative 58.3 0.115329 0.05696 49.39

embodiment 1

Comparative 158.215 0.372734 0.270654 73.42

embodiment 2

Embodiment 1 313.505 0.502816 0.472345 93.94

[53] As can be seen from Table 1, relative to carbon materials prepared from pure

oily sludge, after pore-enlarging treatment with ethanolamine, the total pore volume and

mesoporous volume of adsorbing carbon materials were both increased; after

pore-enlarging treatment with ethanolamine as well as adding nutshell and seed

particles as the pore-enlarging materials, the pore volumes of the prepared adsorbing

carbon materials were further increased, and the proportion of mesopores reached up to

93.94%. Thus, it can be seen that, as a pore-enlarging agent, ethanolamine is beneficial

to increase the pore volume of the adsorbing carbon materials, while adding nutshell

and seed particles as the pore-enlarging materials can take the effect of pore-enlarging

together with ethanolamine, and the synergetic pore-enlarging effect was superior to that

of single ethanolamine.

[54] In order to confirm the beneficial effect of the present disclosure, the inventors

utilized the oily sludge-based adsorbing carbon materials prepared in embodiments 1-4

in the disposals of oily sewage with different oil contents, in which the adding quantity

of the oily sludge-based adsorbing carbon materials was 2 g/L, and the adsorption was

kept at 25°C for 30 min, with the disposal effects shown in Table 2 below.

[55] Table 2 Disposal effects on sewage by the adsorbing carbon materials prepared

in embodiments 1-4

10 17910824_1 (GHMatters) P116825.AU

[561

Adsorbing Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4

carbon

materials

Oil content in 1503.71 2273.83 3042.17 3198.24

sewage (mg/L)

Oil content in 510.90 630.23 680.88 773.32

sewage after

disposal (mg/L)

[57] The oily sludge-based adsorbing carbon material prepared in embodiment 3

was added into the oily sewage at adding quantities of 2 g/L and 4 g/L respectively, and

the adsorption was kept at 25°C for 30 min, with the disposal effects shown in Table 3

below.

[58] Table 3 Disposal effects on sewage by the adsorbing carbon material prepared

in embodiment 3 at different adding quantities

[59]

Adding quantity 2 g/L 4 g/L

Oil content in sewage 3042.17 3042.17

(mg/L)

Oil content in sewage after 680.88 505.21

disposal (mg/L)

[60] It is to be understood that, if any prior art publication is referred to herein, such

reference does not constitute an admission that the publication forms a part of the

common general knowledge in the art, in Australia or any other country.

[61] In the claims which follow and in the preceding description of the invention,

except where the context requires otherwise due to express language or necessary

implication, the word "comprise" or variations such as "comprises" or "comprising" is

used in an inclusive sense, i.e. to specify the presence of the stated features but not to

11 17910824_1 (GHMatters) P116825.AU preclude the presence or addition of further features in various embodiments of the invention.

12 17910824_1 (GHMatters) P116825.AU

Claims

WHAT IS CLAIMED IS:

1. A preparation method of oily sludge-based adsorbing carbon materials for oily

sewage disposal, wherein:

(1) oily sludge that is produced in oil exploitation and refining processes and has

been treated through reduction is dried to a moisture content less than 10%, to get dry

sludge; the dry sludge is mixed evenly with nutshells and seeds that have been crushed

respectively, to get a mixture of raw materials, wherein the mass ratio of nutshells to

seeds is 1-6:1, and the mass ratio of the total mass of nutshells and seeds to the dry

sludge is 1:1-5;

(2) the mixture of raw materials is mixed evenly with ethanolamine at a mass ratio

of 2-5:1, and thermostatically heated at 80-150°C for 3-6 h;

(3) the heat treated products obtained from step (2) are impregnated in an industrial

alkali waste solution at normal temperature for 12-24 h, and upon the completion of

impregnation, they are oven-dried to a constant weight, to prepare activated carbon

precursors;

(4) the activated carbon precursors are placed into a tubular furnace and

thermostatically carbonized at 510-590°C for 1.5-4 h, to prepare carbides;

(5) the carbides are cooled to room temperature and soaked with hydrochloric acid,

and then washed with deionized water until neutral; the washed products are oven-dried

and ground to obtain the oily sludge-based adsorbing carbon materials.

2. The preparation method of oily sludge-based adsorbing carbon materials for oily

sewage disposal according to claim 1, wherein: in step (1), the oily sludge that is

reduction has a moisture content of 60%-65% and an oil content of 5%-10%.

3. The preparation method of oily sludge-based adsorbing carbon materials for oily

sewage disposal according to claim 1, wherein: in step (1), the mass ratio of nutshells to

seeds is 2-3:1, and the mass ratio of the total mass of nutshells and seeds to the dry

sludge is 1:1-3.

13 17910824_1 (GHMatters) P116825.AU

4. The preparation method of oily sludge-based adsorbing carbon materials for oily

sewage disposal according to claim 1, wherein: in step (1), the nutshells are any one or

more of Badam shells, pistachio nut shells, walnut shells, and cottonseed hulls;

wherein: in step (1), the seeds are any one or more of cotton seeds, grape seeds,

watermelon seeds, and passion fruit seeds.

5. The preparation method of oily sludge-based adsorbing carbon materials for oily

sewage disposal according to claim 1, wherein: in step (1), the dry sludge, the nutshells,

and the seeds are crushed into grain sizes of 20-40 meshes respectively;

wherein: in step (2), the mixture of raw materials is mixed evenly with

ethanolamine at a mass ratio of 2.5-4:1, and thermostatically heated at 100-120°C for

3.5-5 h;

wherein: in step (3), the mass-to-volume ratio of the heat treated products to the

industrial alkali waste solution is 1 g:1.5-2.5 mL, the main alkali ingredients in the

industrial alkali waste solution are sodium hydroxide and sodium carbonate, and the

total mass concentration of sodium hydroxide and sodium carbonate is 30%-40%;

wherein: in step (4), the activated carbon precursors obtained from step (3) are

placed into the tubular furnace, where nitrogen is employed as the protective gas, the

gas flow rate is 100-150 mLmin, and the temperature is raised to 530-570°C at a

heating rate of 10-15°C/min, and the carbonization is performed thermostatically for 2-3

h, to prepare the carbides;

wherein: in step (5), the carbides are cooled to room temperature and soaked with

hydrochloric acid at a mass concentration of 5%-10% for 20-30 min, and then washed

with deionized water until neutral; the washed products are oven-dried and ground into

grain sizes of 60-80 meshes, to obtain the oily sludge-based adsorbing carbon materials.

14 17910824_1 (GHMatters) P116825.AU