AU2020244447B2

AU2020244447B2 - Method for preparing efficient dyeing wastewater adsorbent from waste goat hair

Info

Publication number: AU2020244447B2
Application number: AU2020244447A
Authority: AU
Inventors: Xiuliang HOU; Shijin WEI; Helan Xu; Ying Zhu
Original assignee: Jiangnan University
Current assignee: Jiangnan University
Priority date: 2019-06-25
Filing date: 2020-01-16
Publication date: 2022-06-30
Anticipated expiration: 2040-01-16
Also published as: WO2020258863A1; CN110237828B; CN110237828A; AU2020244447A1

Abstract

Disclosed is a method for preparing an efficient dyeing wastewater adsorbent from waste goat hair, which belongs to the field of bio-based adsorption materials. Steam explosion and disintegration with the liquid nitrogen freezing disintegrator are combined to treat the waste goat hair. The steam explosion and disintegration with the liquid nitrogen freezing disintegrator technology used in the present invention is an efficient and environment-friendly pretreatment method. In addition, after the treatment, the goat hair powder has particles of as low as 20 Im, and a crystal index of as low as 2.6%, which increases an amorphous region of the goat hair powder, thereby facilitating the absorption effect of the goat hair. The goat hair adsorbent prepared by the method of the present invention absorbs dyes in dyeing wastewater, with a dye removal rate up to 95%, and an adsorption capacity up to 426 mg/g, which is an excellent biological adsorbent; the goat hair adsorbent prepared by the method of the present invention can repeat adsorption-desorption cycles 5 to 6 times.

Description

Method for Preparing Efficient Dyeing Wastewater Adsorbent from Waste Goat

Hair

Technical Field

[0001] The present invention relates to a method for preparing an efficient dyeing wastewater

adsorbent from waste goat hair, which belongs to the field of bio-based adsorption materials.

Background

[0002] According to statistics, there are 1.074 billion goats globally, which are fed mainly in

China, Mongolia, and Iran. Goats can provide two kinds of fibers, goat hair and cashmere

respectively. Cashmere is one kind of rare animal fibers and is commonly called as "soft gold"

and "gem in fiber". However, its waste goat hair is non-curly, rough and hard, and has low

utilization value. At present, the method of reducing agent-formic acid is mainly used to

prepare goat hair keratin solution. Due to secondary pollution and high cost, these have not

been actually used. Therefore, further research on the application of goat hair is needed.

[0003] Textile dyeing industry leads to a large amount of wastewater. The annual consumption

of dyes in the world exceeds 70,000 tons, of which 45% are reactive dyes. Reactive dyes can be

used to dye cellulose fibers such as cotton and viscose. A large amount of reactive dyes is not

fixed on the cellulose fibers and enter the water to form reactive dye wastewater. Therefore,

the treatment of reactive dye wastewater has become an important issue. Reactive dye 19 (RB

19) is widely used in textile dyeing and is a non-biodegradable pollutant, so it is commonly used

as a model dye in many studies.

[0004] In biological treatment, flocculation, membrane separation processes, chemical

precipitation, adsorption (using activated carbon) and ion exchange and other dyeing

wastewater treatment methods, adsorption has been proven to be an economical and effective

method. With the strengthening of people's awareness of environmental protection, people have put forward higher requirements for adsorbents for treating dye wastewater, requiring environmental protection, low cost, good adsorption performance and reusable.

[0005] The use of agricultural waste as unconventional adsorbents to treat dye wastewater has

become an important topic at present, such as chitosan, polyethyleneimine cationic modified

persimmon tannin adsorbent, wheat straw, coconut leaves, corncob-xylose-based residue

adsorbent, camellia nut shell, fruit peel, etc. Goat wool has a large number of active groups

such as amino and carboxyl groups, which can be used as an adsorbent. While, the problem is

that the amount of adsorption is small. In order to solve this problem, it appears in the

literature that chicken feathers are used as raw materials to extract keratin and then prepare

sponge absorbents, however, the cost is high. Someone proposed to use hair as the raw

material, and after pretreatment with NaOH aqueous solution, it was modified with

formaldehyde and dimethylamine in two steps to prepare a modified keratin adsorbent

containing quaternary ammonium salt. However, the modification method is complicated and

not environmentally friendly.

[0006] The research showed that the extracted keratin from chicken feathers had good

adsorption properties (Song et al., 2017).

Summary

[0007] In an attempt to improve the utilization rate of waste goat hair resources and provide a

low-cost green adsorbent for the treatment of reactive dye wastewater, the present invention

adopts an efficient, environment-friendly and fast pretreatment method, i.e. a steam explosion

method, to perform steam explosion pretreatment on the waste goat hair. After the goat hair is

steam exploded and liquid nitrogen disintegrated, powder with a particle size of 10 to 30 um (in

some embodiments, 15 to 30 um) is obtained, which can be used as a dyeing wastewater

biological adsorbent for treating reactive dye wastewater. The adsorption capacity to reactive dyes is increased from 55 mg/g to 426 mg/g, which increases by about 7 times; and meanwhile, it is ensured that the yield of the goat hair after being steam exploded is 85% or above.

[0008] The present invention discloses a method for preparing an efficient dyeing wastewater

adsorbent from waste goat hair, which adopts steam explosion and disintegration with the

liquid nitrogen freezing disintegrator to treat the waste goat hair.

[0008a] In an embodiment of the present invention, steam explosion conditions are: an

explosion pressure of 1.3 MPa to 1.7 MPa, and an explosion time of 30 s to 240 s.

[0008b] In an embodiment of the present invention, the method comprises the following steps:

(1) steam explosion: performing steam explosion on the waste goat hair, and freeze-drying; and

(2) disintegration with the liquid nitrogen freezing disintegrator: performing the liquid nitrogen

freezing disintegrator on the goat hair in step (1) to obtain the goat hair powder.

[0009] In an embodiment of the present invention, the method comprises the following steps:

[0010] (1) steam explosion: performing steam explosion on the waste goat hair, sieving with a

200 to 300 mesh sieve, and then freeze-drying; and

[0011] (2) disintegration with the liquid nitrogen freezing disintegrator: performing the liquid

nitrogen freezing disintegrator on the goat hair in step (1) to obtain goat hair powder with a

particle size of 10 to 30 Iim.

[0012] Paragraph [0012] is intentionally deleted.

[0013] In an embodiment of the present invention, the freeze-drying in step (1) is to place the

steam-exploded sample at -60 to -80°C for freezing for 1 to 4 h, and then dry the goat hair by

using vacuum freeze-drying.

[0014] In an embodiment of the present invention, vacuum freeze-drying conditions are: a

vacuum degree of 5 to 15 Pa, a temperature of -40 to -60°C, and a drying time of 36 to 72 h.

[0014a] In an embodiment of the present invention, the method comprises the following steps:

(1) steam explosion: performing steam explosion on the waste goat hair, wherein a steam

explosion pressure is 1.5 MPa, and a steam explosion time is 150 s; filtering to remove water in

the steam-exploded goat hair with a 200 mesh screen; placing the steam-exploded sample in an

ultra-low temperature refrigerator at -80°C for 2 h, and then drying the goat hair by a vacuum

freeze-drying method with a vacuum degree of 9.5 Pa, a temperature of -50°C, and a drying

time of 48 h; and

freezing disintegrator on the steam-exploded and dried goat hair to obtain goat hair powder

with a particle size of 20 Iim.

[0014b] The present invention discloses goat hair powder obtained through the method above.

[0015] The present invention discloses a goat hair adsorbent, containing the goat hair powder

obtained through the method above.

[0016] The present invention discloses application of the goat hair adsorbent above in dyeing

wastewater.

[0017] The present invention discloses a method for treating dyeing wastewater with a goat

hair adsorbent, wherein the goat hair powder obtained through the method above is placed

into reactive dye dyeing wastewater for adsorption.

[0018] In an embodiment of the present invention, adsorption conditions are: pH=2 to 5, and a

time of 6 to 10 h.

[0019] In an embodiment of the present invention, a material-to-liquid ratio of the goat hair

powder to the reactive dye dyeing wastewater is 1: (50 to 100).

[0020] Beneficial effects of the present invention are as follows.

[0021] (1) The combined treatment of steam explosion and disintegration used in the present

invention is an efficient and environment-friendly pretreatment method, and compared with

waste goat hair, the treated goat hair has the powder particles of as low as 15 im and the

4a crystal index of as low as 2.6%, which increases the amorphous region of the goat hair powder,

the BET specific surface area of steam exploded and liquid nitrogen disintegrated goat hair is

increased from 0.6777 to 8.5829 m 2 g-1, the BJH adsorption cumulative surface area of pores is

increased from 0.269 m2 g-1 to 5.539 m 2g-1, the volume of pores is increased from 0.170 to 5.41

mm3 g-1, which is superior to the sum of the improvement effects of steam explosion alone and

disintegration alone on the BET specific surface area, the BJH adsorption cumulative surface

area of pores, and BJH adsorption cumulative volume of pores, indicating that the steam

explosion and the disintegration support each other and complement each other in increasing

the specific surface area and pore volume of the goat hair, and are beneficial to the adsorption

of the goat hair.

[0022] (2) The goat hair adsorbent prepared by the method of the present invention adsorbs

dye RB19 in the dyeing wastewater, and the adsorption capacity can reach 426 mg/g, which is

an excellent biological adsorbent.

[0023] (3) The goat hair adsorbent prepared by the method of the present invention can repeat

adsorption-desorption cycles 5-6 times.

Brief Description of Figures

[0024] Fig.1 is SEM images (x800) of different treatments of goat hair; the pressure and time

shown in the figure are the conditions of steam explosion, which are all samples after the

combined treatment of steam explosion and disintegration; CGH is the image of waste goat hair;

FDGH is alone disintegration treatment; EGHP is the combined treatment of steam explosion

and disintegration.

[0025] Fig.2 is XRD spectra of goat hair after the different steam explosion conditions.

[0026] Fig.3 is BET adsorption-desorption isotherm. Including, a: waste goat hair, b: liquid

nitrogen disintegrated goat hair, c: goat hair treated by steam explosion and disintegration

under 1.3MPa, d: goat hair treated by steam explosion and disintegration under 1.5MPa, e:

goat hair treated by steam explosion and disintegration under 1.7MPa.

[0027] Fig.4 is the effect of explosion conditions on adsorption capacity.

[0028] Fig.5 is the relationship between the number of cycles of adsorption and the amount of

adsorption.

[0029] Fig.6 is the adsorption performance of different treatments of goat hair: (a) ~(c) are the

effects of initial dye concentration on the Removal efficiency and adsorption at equilibrium of

different treatments of goat hair. (a) waste goat hair; (b) liquid nitrogen disintegrated goat hair;

(c) goat hair treated by steam explosion and disintegration; (d) ~ (f) are Langmuir and

Freundlich adsorption isotherm curves toward RB19. Including, (d) waste goat hair, (e) liquid

nitrogen disintegrated goat hair and (f) goat hair treated by steam explosion and disintegration.

Detailed Description

[0030] The crystal index (CI) of the samples was calculated based on the Segal's equation.

I o-Io

[0031] CI(%) 914 x 100 (1)

[0032] Where I9 is the intensity of absorption peak at 20 =9 and I 4is the intensity of

absorption valley at 20 =14.

Example 1

[0033] Using steam explosion and disintegration with the liquid nitrogen freezing disintegrator

to treat waste goat hair, comprising the following steps:

[0034] Step 1: Using steam explosion to pretreat waste goat hair:

[0035] (1) performing steam explosion on the waste goat hair, wherein the steam explosion

pressure is 1.5 MPa, and the steam explosion time is 150 s; and

[0036] (2) filtering to remove water in the steam-exploded goat hair with a 200 mesh screen;

and

[0037] (3) placing the steam-exploded sample in an ultra-low temperature refrigerator at -80°C

for 2 h, and then drying the goat hair by a vacuum freeze-drying method with a vacuum degree

of 9.5 Pa, a temperature of -50°C, and a drying time of 48 h; and

[0038] Step 2: disintegration with the liquid nitrogen freezing disintegrator: performing the

liquid nitrogen freezing disintegrator on the steam-exploded and dried goat hair to obtain goat

hair powder with a particle size of 20 im. The goat hair has a small size and small voids inside,

which has a strong adsorption effect.

[0039] Step 3: Using the goat hair powder prepared above to treat dyeing wastewater:

[0040] (1) placing the goat hair powder by steam-exploded and disintegrated into reactive dye

19 dyeing wastewater for adsorption, which adsorption conditions are pH=2, 8 hours at 21°C,

and the amount of the steam-exploded goat hair is 10g/L;

[0041] (2) Using the No. 5 sand core funnel to filter to obtain purified water and goat hair

adsorbing reactive blue 19 dye.

Example 2: Effect of different steam explosion conditions on the properties of goat wool

powder

[0042] 1. The influence of different steam pressure on goat hair performance:

[0043] The method of Example 1 was used to treat waste goat hair. The only difference was

that the steam flash explosion pressure was 1.3 MPa and 1.7 MPa, and the particle size of the

goat hair obtained after treatment was about 36im and 18 pm, respectively. The adsorption

performance and the crystal index of goat hair are shown in Fig. 4, Table 1 and Table 2.

[0044] 2. The influence of different steam treatment time on goat hair performance:

[0045] The method of Example 1 was used to treat waste goat hair. The only difference was

that the steam treatment time was 30 s, 90 s, and 240 s, and the particle sizes of the goat hair

obtained after treatment were 42 m, 38 pm, and 19 m. The adsorption performance and

crystal index of goat hair are shown in Fig. 4 and Table 2.

[0046] Table 1 Effect of different steam explosion conditions on the properties of goat wool

powder

Steam pressure Steam treatment Crystal Relative Crystal Group Ii Iii /MPa time/s Index Index Control 0 150 3342 2337 30.1 100 Al 1.3 150 2189 2012 8.1 27 A2 (Example 1.5 150 2062 1951 5.4 18 1)

A3 1.7 150 2011 1959 2.6 8.6 Control 1.5 0 3342 2337 30.1 100 BI 1.5 30s 2138 1977 8 26.5 B2 1.5 90s 2063 1935 6.2 20.6 B3 1.5 240s 2067 1959 5.2 17.3

[0047] It can be seen from Fig. 1 that the scales of goat hair are destroyed under the steam

condition of 1.3 MPa, 1.5 MPa and 1.7 MPa. As the steam pressure increases, the scales of goat hair are damaged more seriously. Therefore, it is expected that in the process of adsorption of

RB19 by steam exploded goat hair, the dye will more easily enter the amorphous region of goat

hair without the hindrance of scales to improve the adsorption performance. At the same time,

more adsorption sites of goat hair are exposed after the scales are destroyed. This is also an

important factor of improving the adsorption performance of steam exploded goat hair. The

microscopic surface scales of goat wool are destroyed when treated with 30s, 90s, 150s and

240s, however, the damage of scales slightly increased with the extended steam treatment

time. After the goat hair treated with liquid nitrogen, the size becomes smaller, and the specific

surface area of goat hair increases, leading to exposing more adsorption sites and further

improvement of the adsorption performance. At the same time, adsorbent with small particles

usually have a higher specific surface area than that with large particles, which can expose

more available adsorption active sites, thus leading to higher adsorption. In this study, the goat

hair with smaller size (<150pim) has stronger adsorption performance for RB19 than the

centimeter-sized goat hair. Particle size is only one aspect, scale destruction, crystallinity, and

pore size are also reasons for the increase in adsorption capacity.

[0048] As can be seen from Fig. 4, the adsorption capacity of goat hair obviously increased with

the increased steam pressure from 1.3 to 1.8 MPa. The adsorption capacity of goat hair under

the steam explosion of 1.3 MPa, 1.5 MPa and 1.7 MPa is 286.4 mg/g, 385.8 mg/g and 426.7

mg/g, respectively. The adsorption capacity of the goat hair treated with steam explosion and

liquid nitrogen under 1.3 MPa, 1.5 MPa, 1.7 MPa, is about 5, 7, 8 times of waste goat hair.

However, the extension of the treatment time will not bring about a significant increase in the

adsorption capacity.

[0049] It can be seen from Table 1 and 2 that the crystal index of waste goat hair is 30.1%, and

the crystal index of goat hair decreases after a certain steam pressure. The crystallization

indices of the goat hair treated with steam explosion under the pressure of 1.3 MPa, 1.5 MPa and 1.7 MPa and treatment time of 150 s are 8.1%, 5.4%, and 2.6%, respectively. Therefore, it indicated that the amorphous region of goat hair expanded after the steam explosion, so that more RB19 molecules could be adsorbed into the expanded amorphous region of exploded goat hair, and the adsorption capacity improved. Moreover, as the steam pressure changes from 1.3

MPa to 1.7 MPa, the crystal index of flash goat hair is further reduced, and the internal

amorphous region of exploded goat hair is further expanded. This promotes the further

improvement of the adsorption capacity of exploded goat hair to RB19. However, under a

certain steam pressure, the crystal index of steam explosion goat hair does not decrease

significantly with the extension of the treatment time. Therefore, it can be said that treatment

time has no obvious promoting effect on the ability of exploded goat hair to absorb dyes.

Generally speaking, as for goat hair, steam pressure is the key factor to improve the adsorption

capacity of goat hair to RB19.

[0050] Example 3: Reuse of goat hair adsorbent

[0051] Desorption and repeated adsorption of goat hair adsorbent include the following steps:

[0052] (1) Wash the goat hair after adsorbing the dye inO.1g/L NaOH for 30 minutes to achieve

desorption;

[0053] (2) subsequently washed with distilled water till neutral, and freeze-dry the collected

desorbed goat hair again;

[0054] (3) Repeatedly adsorb the desorbed goat hair. The adsorption conditions are the same

as those in step 3 in Example 1. The result is shown in Fig. 5 that goat wool adsorbent can

repeat the adsorption and desorption cycle 5-6 times.

[0055] Comparative example 1:

[0056] The original abandoned goat hair without any treatment, the SEM image, XRD image,

adsorption performance and crystal index of goat hair are shown in Figure 1, 2, 6 and Table 1-3.

[0057] Comparative example 2: separate treatment of steam explosion

[0058] The method of Example 1 was used to treat waste goat hair. The difference is that the

waste goat hair was treated separately by steam explosion under 1.5MPa and 150s. The size of

the goat hair obtained was 20 pm. The SEM image, XRD image, performance of adsorption and

crystal index are shown in Figure 1, 2, 6 and Table 1-3.

[0059] Comparative example 3: separate treatment of the liquid nitrogen freezing

disintegrator

[0060] The method of Example 1 was used to treat waste goat hair. The difference is that the

waste goat hair was treated separately by the liquid nitrogen freezing disintegrator. The

particle size of the obtained goat hair was 150 m. The SEM image and specific surface area

adsorption performance of goat hair are shown in Fig. 1 and Table. 3 and Fig. 4.

[0061] Table. 2 surface area and pore size of goat wool after different treatment

BET specific BJH adsorption BJH adsorption BJH adsorption Sample surface Area cumulative surface cumulative volume of average pore width m 2 /g area of pores m 2/g pores cm 3/g (4V/A)

Comparative 0.6777 0.269 0.000170 25.332A example 1

Comparative 1.0544 0.310 0.00175 22.601A example 2

Comparative 0.7777 0.369 0.000270 26.132A example 3

Al 3.0520 2.187 0.002091 38.244A

Example 1 4.4102 3.189 0.003405 42.720A

A3 8.5829 5.539 0.005419 39.134A

[0062] Table. 3 adsorption ability of goat wool after different treatment

BJH adsorption Adsorption Sample Diameter /pm Crystal index cumulative volume of poresm 3 /g capacity (mg/g) pores cm 3/

Comparative 1001pm 30.1 0.000170 55 example 1

Comparative 60 8.5 0.00175 180 example 2

Comparative 150 29.5 0.000175 124 example 3

Al 36 8.1 0.002091 286

Example 1 20 5.4 0.003405 426

A3 18 2.6 0.005419 326

[0063] It can be seen from Table 2 that compared with Comparative Example 1 (blank group),

the BET specific surface area and BJH adsorption cumulative surface area of pores of the steam

exploded goat hair powder in Comparative Example 2 increased by 0.3767 m 2 /g and 0.041

m 2/g, respectively. Comparing with Comparative Example 1 (blank group), the BET specific

surface area and BJH adsorption cumulative surface area of pores of the liquid nitrogen

disintegrated goat hair powder in Comparative Example 3 increased by 0.1 m 2 /g and 0.1m 2/g,

respectively. While, Comparing with Comparative Example 1 (blank group), the BET specific

surface area and BJH adsorption cumulative surface area of pores of steam exploded and liquid

nitrogen disintegrated goat hair powder in Example 1 were increased by 3.7325 m 2 /g and 1.918

m 2/g, respectively. It is superior to the sum of the improvement effects of steam explosion

alone and disintegration alone on the BET specific surface area and the BJH adsorption

cumulative surface area of pores (0.4767 m 2 /g and 0.141 m 2/g), indicating that the steam

explosion and the disintegration support each other and complement each other in increasing the specific surface area and pore volume of the goat hair, and are beneficial to the adsorption of the goat hair.

[0064] It can be seen from Table 3 that compared with Comparative Example 1 (blank group),

the goat hair obtained by steam explosion treatment alone (comparative example 2) has an

adsorption capacity of 180 mg/g for dyes, which is 125 mg/g higher than that of comparative

example 1 (blank group). The goat hair obtained by disintegration alone (Comparative Example

3) has an adsorption capacity of 124mg/g for dyes, which is 69 mg/g higher than that of

Comparative Example 1 (blank group). Example 1 was obtained by the combined treatment of

steam flash explosion and disintegration has an adsorption capacity of 426 mg/g for dyes,

which has an increase of 371 mg/g compared with Comparative Example 1 (blank group). It is

superior to the sum of the improvement effects of steam explosion alone and disintegration

alone on the dye adsorption capacity (194 mg /g), indicating that the steam explosion and the

disintegration support each other and complement each other in increasing the specific surface

area and pore volume of the goat hair, and are beneficial to the adsorption of the goat hair. The

crystallization index of goat hair treated by steam explosion alone is 8.5, and the crystallization

index of goat hair by disintegration alone is 29.5, while the steam exploded and liquid nitrogen

disintegrated goat hair is 5.4. It indicates that disintegration alone does not change the

crystallinity of goat hair.

[0065] The reference to any prior art in this specification is not, and should not be taken as, an

acknowledgement or any form of suggestion that such prior art forms part of the common

general knowledge.

[0066] It will be understood that the terms "comprise" and "include" and any of their

derivatives (e.g. comprises, comprising, includes, including) as used in this specification, and the

claims that follow, is to be taken to be inclusive of features to which the term refers, and is not

meant to exclude the presence of any additional features unless otherwise stated or implied.

[0067] In some cases, a single embodiment may, for succinctness and/or to assist in

understanding the scope of the disclosure, combine multiple features. It is to be understood

that in such a case, these multiple features may be provided separately (in separate

embodiments), or in any other suitable combination. Alternatively, where separate features are

described in separate embodiments, these separate features may be combined into a single

embodiment unless otherwise stated or implied. This also applies to the claims which can be

recombined in any combination. That is a claim may be amended to include a feature defined in

any other claim. Further a phrase referring to "at least one of" a list of items refers to any

combination of those items, including single members. As an example, "at least one of: a, b, or

c" is intended to cover: a, b, c, a-b, a-c, b-c, and a-b-c.

[0068] It will be appreciated by those skilled in the art that the disclosure is not restricted in its

use to the particular application or applications described. Neither is the present disclosure

restricted in its preferred embodiment with regard to the particular elements and/or features

described or depicted herein. It will be appreciated that the disclosure is not limited to the

embodiment or embodiments disclosed, but is capable of numerous rearrangements,

modifications and substitutions without departing from the scope as set forth and defined by

the following claims.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A method for preparing an efficient dyeing wastewater adsorbent from waste goat hair,

comprising: treating the waste goat hair using a combination of steam explosion and

disintegration with the liquid nitrogen freezing disintegrator to obtain goat hair powder as the

adsorbent for treating dyeing wastewater.

2. The method according to claim 1, wherein steam explosion conditions are: an explosion

pressure of 1.3 MPa to 1.7 MPa, and an explosion time of 30 s to 240 s.

3. The method according to either claim 1 or claim 2, wherein the method comprises the

following steps:

4. The method according to claim 3, wherein the method comprises the following steps:

(1) steam explosion: performing steam explosion on the waste goat hair, sieving with a 200 to

300 mesh sieve, and then freeze-drying; and

freezing disintegrator on the goat hair in step (1) to obtain goat hair powder with a particle size

of 10 to 30 pm.

5. The method according to either claim 3 or claim 4, wherein the freeze-drying in step (1) is to

freeze the steam-exploded sample at -60 to -80°C for 1to 4 h, and then dry the goat hair by

vacuum freeze-drying.

6. The method according to claim 5, wherein vacuum freeze-drying conditions are: a vacuum

degree of 5 to 15 Pa, a temperature of -40 to -60°C, and a drying time of 36 to 72 h.

7. The method according to any one of claims 1 to 6, wherein the method comprises the

following steps:

time of 48 h; and

with a particle size of 20 im.

8. Goat hair powder prepared by applying the method according to any one of claims 1 to 7.

9. A goat hair adsorbent, containing the goat hair powder according to claim 8.

10. Use of the goat hair adsorbent according to claim 9 in dyeing wastewater.

11. A method for treating dyeing wastewater with a goat hair adsorbent, comprising: placing

the goat hair powder according to claim 8 into reactive dye dyeing wastewater for adsorption.

12. The method according to claim 11, wherein adsorption conditions are: pH=2 to 5, and a

time of 6 to 10 h.

13. The method according to either claim 11 or claim 12, wherein a material-to-liquid ratio of

the goat hair powder to the reactive dye dyeing wastewater is 1: (50 to 100).