WO2020258863A1

WO2020258863A1 - Method for preparing high-efficiency dyeing wastewater adsorbent from waste goat hair

Info

Publication number: WO2020258863A1
Application number: PCT/CN2020/072395
Authority: WO
Inventors: 侯秀良; 魏世锦; 朱莹; 徐荷澜
Original assignee: 江南大学
Priority date: 2019-06-25
Filing date: 2020-01-16
Publication date: 2020-12-30
Also published as: CN110237828B; AU2020244447A1; CN110237828A; AU2020244447B2

Abstract

The present invention relates a method for preparing a high-efficiency dyeing wastewater adsorbent from waste goat hair and belongs to the field of bio-based adsorption material. The method uses steam flash explosion and liquid nitrogen pulverization to process waste goat hair. After the process, the powder particles of the goat hair are as small as 20 μm, and the crystallization index is as low as 2.6%, which increases the amorphous area of the goat hair powder and facilitates adsorption by goat hair. The goat hair adsorbent prepared by the method adsorbs the dye in the dyeing wastewater. The removal rate of dye is as high as 95%, and the adsorption capacity is as high as 426 mg/g. The goat hair adsorbent can repeat adsorption-desorption cycles 5-6 times.

Description

Method for preparing high-efficiency dyeing wastewater adsorbent from waste goat hair

Technical field

The invention provides a method for preparing an adsorbent for high-efficiency dyeing wastewater from waste goat hair, which belongs to the field of bio-based adsorbent materials.

Background technique

According to data, 1.074 billion goats are raised globally, mainly in Asia and Africa such as China, Mongolia, and Pakistan. Goats provide goat wool and cashmere fibers during growth. Cashmere is a kind of rare special animal fiber, commonly known as "soft gold" and "fiber gem". Its product feels soft, smooth, and has an elegant and noble style. China's cashmere output and quality rank first in the world. However, the 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.

Textile industry enterprises produce a large amount of dye wastewater. The annual consumption of dyes in the world exceeds 70,000 tons, and 45% of these dyes are reactive dyes. These dyes can color cellulose fibers such as cotton and viscose. A large amount of reactive dyes are 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. RB19 is widely used in textile dyeing and is a non-biodegradable pollutant, so it is usually used as a model dye in many studies.

In biological treatment, flocculation, membrane separation process, 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.

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, based on corn cob-xylose Adsorbent for residues, camellia nut shells, fruit peels, etc. Goat wool has a large number of active groups such as amino and carboxyl groups, which can be used as adsorbents. The problem is that the amount of adsorption is small. 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 then modify it with formaldehyde and dimethylamine in two steps after pretreatment with NaOH aqueous solution to prepare a modified keratin adsorbent containing quaternary ammonium salt. However, the modification method is complicated. And not environmentally friendly.

Summary of the invention

In order 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, environmentally friendly and fast pretreatment method, steam flash explosion method, to steam the waste goat hair. Flash explosion pretreatment. Goat wool is subjected to flash explosion and liquid nitrogen pulverization to obtain powder with a particle size of 15 ~ 30um, which can be used as a biological adsorbent for dyeing wastewater for the treatment of reactive dye wastewater. The adsorption capacity of reactive dyes has increased from 55mg/g to 426mg/ g, increased by about 7 times; at the same time, ensure that the yield of goat hair after steam flash explosion is above 85%.

The first object of the present invention is to provide a method for preparing high-efficiency dyeing wastewater adsorbent from waste goat hair, which adopts steam flash explosion and liquid nitrogen pulverization to treat the waste goat hair.

The second object of the present invention is to provide a method for preparing an adsorbent for high-efficiency dyeing wastewater from waste goat hair, which includes the following steps:

(1) Steam flash explosion: steam flash explosion of waste goat hair, freeze-dry after passing through a 200-300 mesh sieve;

(2) Liquid nitrogen pulverization: the goat hair of step (1) is pulverized with liquid nitrogen to obtain goat hair powder with a particle size of 10-30 μm.

In one embodiment of the present invention, the steam flash explosion conditions are: flash explosion pressure 1.3MPa-1.7MPa, flash explosion time 30s-240s.

In one embodiment of the present invention, the freeze-drying in the step (1) is to put the sample after the steam flash explosion into -60～-80℃ for 1～4h, and then use vacuum freeze-drying to freeze the goat hair drying.

In one embodiment of the present invention, the vacuum freeze-drying conditions are as follows: vacuum degree is 5-15 Pa, temperature is -40--60°C, and drying time is 36-72h.

The third object of the present invention is to provide a goat hair adsorbent containing goat hair powder obtained by the above method.

The fourth objective of the present invention is to provide an application of the above goat hair adsorbent in dyeing wastewater.

The fifth object of the present invention is to provide a method for treating dyeing wastewater with goat hair adsorbent. The goat hair powder obtained by the above method is put into reactive dye dyeing wastewater for adsorption.

In one embodiment of the present invention, the adsorption condition is pH=2-5, and the time is 6-10h.

In one embodiment of the present invention, the material-to-liquid ratio of the goat hair powder to the reactive dye dyeing wastewater is 1: (50-100).

The beneficial effects of the present invention:

(1) The combined treatment of steam flash explosion and liquid nitrogen pulverization used in the present invention is an efficient and environmentally friendly pretreatment method. Compared with waste goat hair, the goat hair powder particles are as low as 15 μm and the crystallization index is as low as 2.6. %, increased the amorphous area of goat hair powder, the BET specific surface area of steam flash explosion + liquid nitrogen crushed goat hair increased from 0.6777 to 8.5829m ² g ^-1 , and the cumulative specific surface area of its BJH adsorption pores increased from 0.269m ² g ^-1 increased to 5.539m ² g ^-1 , and its pore volume increased from 0.170 to 5.41mm ³ g ^-1 , which is more effective than steam flash explosion and liquid nitrogen smashing alone on BET specific surface area, BJH adsorption pore cumulative specific surface area, and BJH adsorption cumulative The sum of the effect of increasing the pore volume is more superior, indicating that steam flash explosion and liquid nitrogen crushing support each other in increasing the specific surface area and pore volume of goat hair, complement each other, and facilitate the adsorption of goat hair;

(2) The goat hair adsorbent prepared by the method of the present invention adsorbs the dye RB19 in the dyeing wastewater, and the adsorption capacity can reach 426mg/g, which is an excellent biological adsorbent;

(3) The goat hair adsorbent prepared by the method of the present invention can repeat adsorption and desorption cycles for 5-6 times.

Description of the drawings

Figure 1 SEM images of different treatments of goat hair; the pressure and time shown in the figure are the conditions of steam flash explosion, which are all samples after the combined treatment of steam flash explosion + liquid nitrogen crushing; CGH: photo of waste goat hair; FDGH: alone Liquid nitrogen crushing treatment; EGHP: steam flash explosion + liquid nitrogen crushing combined treatment.

Figure 2 XRD spectra of goat hair under different steam flash explosion conditions.

Figure 3 BET adsorption-desorption isotherm; among them, a: waste goat hair, b: liquid nitrogen crushed goat hair, c: steam flash explosion + liquid nitrogen crushed goat hair-1.3MPa, d: steam flash explosion + liquid nitrogen Goat wool crushed -1.5MPa, e: steam flash explosion + liquid nitrogen crushed goat wool -1.7MPa.

Figure 4 The effect of flash explosion conditions on adsorption capacity.

Figure 5 The relationship between the number of cycles of adsorption and the amount of adsorption.

Figure 6: Adsorption performance of different treatment goat hair: (a)～(c) are the influence of initial dye concentration on the adsorption performance and dye removal efficiency of different treatment goat hair; among them, (a) waste goat hair; (b) liquid nitrogen Smash goat hair; (c) steam flash explosion + liquid nitrogen to smash goat hair; (d)～(f) are Langmuir adsorption isotherms of different treatment goat hair adsorbing reactive blue 19; among them, (d) waste goat hair; (e) ) Liquid nitrogen crushes goat hair; (f) Steam flash explosion + liquid nitrogen crushes goat hair.

Detailed ways

Use Segal equation to calculate the crystal index (CI) of the sample:

CI(%)=(I ₉ °-I ₁₄ °)/I ₉ °×100 (1)

I ₉ ° is the absorption peak intensity at 2θ=9°, and I ₁₄ ° is the absorption valley intensity at 2θ=14°.

Example 1:

Use steam flash explosion and liquid nitrogen crushing technology to process waste goat hair, the specific steps are as follows:

Step 1: Use steam flash explosion to pre-treat waste goat hair:

(1) Perform steam flash explosion on discarded goat hair, the steam flash explosion pressure is 1.5MPa, and the steam flash explosion time is 150s;

(2) Use a 200-mesh screen to filter and remove the water in goat hair after steam flash explosion;

(3) Put the sample after the steam flash explosion into an ultra-low temperature refrigerator at -80℃ for 2h, and then use a vacuum freeze-drying method to dry goat hair with a vacuum degree of 9.5Pa, a temperature of -50℃, and a drying time of 48h;

Step 2: Liquid nitrogen freezing and crushing: The flash-exploded and dried goat hair is pulverized with liquid nitrogen to obtain goat hair powder with a particle size of 20 μm. The goat hair is small in size and has small voids inside, which has a strong adsorption effect.

Step 3: Use the goat hair powder prepared above to treat dyeing wastewater:

(1) Put the flash-exploded and crushed powdered goat hair into reactive blue dye 19 dyeing wastewater for adsorption, adsorption conditions: pH=2, 8 hours at 21°C, dosage of flash-exploded goat hair: 10g/L;

(2) Use 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 flash explosion conditions on the properties of goat hair powder

1. The influence of different flash explosion pressure on goat hair performance:

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 36 μm and 18 μm, respectively. The adsorption performance and crystallization of goat hair The index is shown in Figure 4 and Table 1 and Table 2.

2. The effect of different flash explosion time on goat hair performance:

The method of Example 1 was used to treat waste goat hair. The only difference was that the steam holding time was 30s, 90s and 240s, and the particle size of the goat hair obtained after the treatment was 42μm, 38μm, 19μm, respectively. The adsorption performance and The crystallization index is shown in Figure 4 and Table 2.

Table 1 The influence of different steam flash explosion conditions on the properties of goat hair powder

It can be seen from Figure 1 that the surface scales of goat hair are destroyed after certain steam flash explosion conditions (1.3, 1.5, 1.7MPa). As the steam flash explosion pressure increases, the microscopic surface scales of goat hair are more severely damaged. Therefore, it is expected that in the process of adsorption of RB19 by steam flashed 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, after the scales are destroyed, more adsorption sites on goat hair are exposed. This is also an important factor in improving the adsorption performance of steam flashed goat hair. After a certain holding time (30, 90, 150, 240s) of goat hair, the microscopic surface scales of goat hair are destroyed. However, the length of holding time affects the microstructure of goat hair. The effect is not obvious. After the goat hair is pulverized with liquid nitrogen, the size becomes smaller and the specific surface area of goat hair increases, exposing more adsorption sites, and the adsorption performance will be further improved. At the same time, small adsorbent particles usually have a higher specific surface area than large particles, which can expose more available adsorption active sites, thus leading to higher adsorption. In this study, compared with centimeter-sized goat hair, goat hair of smaller size (<150μm) has stronger adsorption performance for RB19. Particle size is only one aspect, scale destruction, crystallinity, and pore size are also reasons for the increase in adsorption capacity.

It can be seen from Figure 4 that the steam flash explosion pressure is increased from 1.3 MPa to 1.7 MPa, and the adsorption capacity of goat hair is significantly increased. The adsorption capacity of flash explosion goat hair after 1.3MPa, 1.5MPa, 1.7MPa is 286.4, 385.8, 426.7mg/g, and steam flash explosion + liquid nitrogen crushed goat hair 1.3MPa, 1.5MPa, 1.7MPa The adsorption capacity is about 5, 7, 8 times that of waste goat hair. However, the extension of the holding time will not bring about a significant increase in the adsorption capacity.

It can be seen from Tables 1 and 2 that the crystallization index of waste goat hair is 30.1%, and the crystallization index of goat hair decreases after flash explosion at a certain steam pressure. The crystallization indices of flash goat hair treated with steam pressures of 1.3 MPa, 1.5 MPa, and 1.7 MPa and a pressure holding time of 150 s were 8.1%, 5.4%, and 2.6%, respectively. Therefore, it can be explained that the amorphous area of goat hair is expanded after flash explosion at a certain steam pressure, so that more RB19 enters the amorphous area of flash goat hair, and the adsorption capacity of flash goat hair to RB19 is improved. Moreover, as the vapor pressure changes from 1.3 MPa to 1.7 MPa, the crystallization index of flash goat hair is further reduced, and the internal amorphous area of flash goat hair is further expanded. This promotes the further improvement of the adsorption capacity of flash explosion goat hair to RB19. However, under a certain vapor pressure, the crystallization index of flash explosion goat hair does not decrease significantly with the extension of the holding pressure time. Therefore, it can be said that holding pressure time has an effect on the flash explosion mountain. The ability of wool to absorb dyes has no obvious promoting effect. Generally speaking, for goat hair, steam pressure is the key factor to improve the adsorption capacity of goat hair to RB19.

Example 3: Reuse of goat hair adsorbent.

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

(1) Wash the goat hair after adsorbing the dye in 0.1g/L NaOH for 30 minutes to achieve desorption;

(2) Wash the desorbed goat hair with deionized water until it is neutral, and freeze-dry the collected desorbed goat hair again;

(3) The desorbed goat hair was repeatedly adsorbed, and the adsorption conditions were the same as those in step 3 in Example 1, and the result is shown in FIG. 6. Goat wool adsorbent can repeat the adsorption and desorption cycle 5-6 times.

It can be seen from Figure 5 that the goat hair adsorbent can repeat the adsorption and desorption cycle 5-6 times.

Comparative example 1:

The original abandoned goat hair without any treatment, the SEM image, XRD image, adsorption performance and crystallization index of goat hair are shown in Figure 1, 2, 6 and Table 1-3.

Comparative example 2: separate treatment of steam flash explosion

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 flash explosion (1.5MPa, 150s). The size of the goat hair obtained was 20μm. The SEM image, XRD image and adsorption performance of goat hair And crystallization index is shown in Figure 1, 2, 6 and Table 1-3.

Comparative example 3: Liquid nitrogen crushed separately

The method of Example 1 was used to treat waste goat hair. The difference is that the waste goat hair was treated separately by liquid nitrogen pulverization. The particle size of the obtained goat hair was 150 μm. The SEM image and specific surface area adsorption performance of goat hair are shown in Figure 1 and Table 3. With Figure 4.

Table 2 Specific surface area and pore size of goat hair with different treatments

Table 3 Absorption performance of goat hair with different treatments

It can be seen from Table 2 that the BET specific surface area and the cumulative specific surface area of the BJH adsorption pores of goat hair powder obtained by the separate steam flash explosion treatment (Comparative Example 2) are increased by 0.3767m ^{2 /} g and 0.041m respectively compared with Comparative Example 1 (blank group). ² / g; crushed in liquid nitrogen alone (Comparative Example 3) BET goat hair powder was accumulated BJH adsorption pore specific surface area and specific surface area compared with Comparative Example 1 (control group) were increased by 0.1m ^² /g,0.1m ² /g; and the BET specific surface area and the cumulative specific surface area of the BJH adsorption pores of the goat hair powder obtained by the combined treatment of steam flash explosion and liquid nitrogen pulverization in Example 1 were increased by 3.7325m ² /g, compared with Comparative Example 1 (blank group). 1.918m ² / g, and the steam explosion than either alone accumulated pulverized in liquid nitrogen surface area and to enhance the effect of the BET specific surface area and BJH adsorption pore (respectively 0.4767m ^² /g,0.141m ² / g) superior described Steam flash explosion and liquid nitrogen crushing support each other and complement each other in increasing the specific surface area and pore volume of goat hair.

It can be seen from Table 3 that the goat hair obtained by steam flash explosion treatment (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 dye adsorption capacity of goat hair obtained in proportion 3) was 124 mg/g, which was 69 mg/g higher than that of comparative example 1 (blank group); in Example 1, the goat hair powder obtained by the combined treatment of steam flash explosion and liquid nitrogen crushing The dye adsorption capacity is 426mg/g, which is an increase of 371mg/g compared to Comparative Example 1 (blank group), which is superior to the sum of the effect of steam flash explosion and single liquid nitrogen crushing on the dye adsorption capacity (194mg/g). It shows that steam flash explosion and liquid nitrogen crushing support each other and complement each other in enhancing the adsorption effect of goat hair on dyes. The crystallization index of goat hair treated by steam flash explosion alone is 8.5, the crystallization index of goat hair pulverized by liquid nitrogen alone is 29.5, steam flash explosion + liquid nitrogen pulverization treatment is 5.4, indicating that liquid nitrogen pulverization alone does not change the crystallinity of goat hair. Big.

Although the present invention has been disclosed as above in preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. The protection scope of the present invention should be defined by the claims.

Claims

A method for preparing a high-efficiency dyeing wastewater adsorbent from waste goat hair, which is characterized in that the waste goat hair is combined with steam flash explosion and liquid nitrogen pulverization to obtain goat hair powder as an adsorbent for treating dyeing wastewater; the steam flash explosion conditions are ：Flash explosion pressure 1.3MPa-1.7MPa, flash explosion time 30s-240s; the method includes the following steps:

(1) Steam flash explosion: steam flash explosion of waste goat hair, freeze-dry after passing through a 200-300 mesh sieve;

(2) Liquid nitrogen pulverization: the goat hair of step (1) is pulverized with liquid nitrogen to obtain goat hair powder with a particle size of 10-30 μm.
A method for preparing high-efficiency dyeing wastewater adsorbent from waste goat hair is characterized in that the waste goat hair is combined with steam flash explosion and liquid nitrogen crushing to obtain goat hair powder as an adsorbent for treating dyeing wastewater.
The method according to claim 1, characterized by comprising the following steps:

(1) Steam flash explosion: steam flash explosion of discarded goat hair and freezing;

(2) Liquid nitrogen pulverization: the goat hair of step (1) is pulverized with liquid nitrogen to obtain goat hair powder.
The method according to claim 2 or 3, wherein the steam flash explosion conditions are: flash explosion pressure 1.3MPa-1.7MPa, flash explosion time 30s-240s.
The method according to claim 3, wherein the freeze-drying in the step (1) is to freeze the sample after the steam flash explosion at -60 to -80°C for 1 to 4 hours.
The method according to claim 5, wherein the vacuum freeze-drying conditions are: a vacuum degree of 5-15 Pa, a temperature of -40--60°C, and a drying time of 36-72h.
The method according to claim 3, characterized in that said comprises the following steps:

(1) Steam flash explosion: steam flash explosion of waste goat hair, freeze-dry after passing through a 200-300 mesh sieve;

(2) Liquid nitrogen pulverization: the goat hair of step (1) is pulverized with liquid nitrogen to obtain goat hair powder with a particle size of 10-30 μm.
The method according to claim 3, characterized in that said comprises the following steps:

(1) Steam flash explosion: perform steam flash explosion on waste goat hair, the steam flash explosion pressure is 1.5MPa, and the steam flash explosion time is 150s; a 200 mesh screen is used to filter and remove the water in the goat hair after the steam flash explosion; the steam The flash-exploded samples were placed in an ultra-low temperature refrigerator at -80°C for 2 hours, and then the goat hair was dried by a vacuum freeze-drying method with a vacuum of 9.5 Pa, a temperature of -50°C, and a drying time of 48 hours;

(2) Liquid nitrogen pulverization: pulverize the flashed and dried goat hair with liquid nitrogen to obtain goat hair powder with a particle size of 20 μm.
Goat wool powder prepared by the method of any one of claims 1-8.
A goat hair adsorbent, characterized in that it contains the goat hair powder according to claim 9.
The use of the goat hair adsorbent of claim 10 in dyeing wastewater.
A method for treating dyeing wastewater with goat hair adsorbent, characterized in that the goat hair powder according to claim 9 is put into reactive dye dyeing wastewater for adsorption.
The method according to claim 12, characterized in that the adsorption conditions are pH=2-5, and the time is 6-10h.
The method according to claim 12, wherein the material-liquid ratio of the goat hair powder to the reactive dyeing wastewater is 1: (50-100).