Preparation method and application of basalt fiber fabric-based electric flocculation composite cathode material

Abstract

The application discloses a preparation method of a basalt fiber fabric-based electric flocculation composite cathode material and application thereof. The preparation method of the basalt fiber fabric-based electric flocculation composite cathode material first immerses basalt fiber fabric into a carbon nanotube dispersion liquid, then performs coating in a self-made silver nanowire solution, and finally obtains a silver nanowire-carbon nanotube-basalt fiber fabric composite cathode material. The method is simple, efficient, green, low in cost, wide in application range and suitable for large-scale application production. The obtained composite cathode material has excellent electrical conductivity, good mechanical strength, and is superior to and can replace traditional electric flocculation metal cathode materials such as aluminum (Al) plates, iron (Fe) plates, magnesium (Mg) plates, titanium (Ti) plates and zinc (Zn) plates in chemical stability, corrosion resistance, specific surface area and flexibility. Meanwhile, the material improves the efficiency of the electric flocculation technology in treating oil-containing wastewater, the oil-water separation effect reaches more than 90%, and expands the application of the basalt fiber fabric-based composite material in important fields such as environmental electrochemistry, energy electronics, sewage treatment and petroleum chemical industry.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of basalt fiber fabric modification and composite electrode materials, and particularly relates to a preparation method of a basalt fiber fabric-based cathode material and application of the basalt fiber fabric-based cathode material in an electric flocculation oil-water separation process. BACKGROUND

[0002] In recent years, new materials with high oil / water separation efficiency and recyclability have attracted extensive attention from researchers at home and abroad. At present, membranes, filters, sponges and various textile fabrics are developed by coating specific chemicals, adding different nanoparticles and organic compounds, and are applied to oil-containing wastewater treatment technologies such as adsorption technology, advanced oxidation process, membrane technology and electrochemical process. However, these materials have the disadvantages of high preparation cost, complex process and no environmental protection, which limit their application in the field of electrochemical oil-water separation methods. Compared with other oil-water separation technologies, the electric flocculation technology has the advantages of simple equipment, convenient operation, green environmental protection, generally no need to add chemical reagents, less sludge production and high treatment efficiency, and it is considered as one of the ideal technologies to realize efficient oil-water separation. Electrode materials (anode and cathode) are the core structural components of the electric flocculation technology. In the electric flocculation process, the anode electrolysis produces metal ions such as iron, aluminum and magnesium. The cathode electrolysis produces hydrogen (H2) and hydroxyl ions. Hydrogen gas has a gas floating effect, which can remove colloids, suspended substances and other substances in wastewater. In addition, the hydroxyl ions react with metal ions and pollutants to form flocculation groups. The flocculation groups migrate directionally under the action of the electric field, so as to achieve the purpose of removing pollutants. Therefore, in the electric flocculation process, the selection of cathode materials will also affect the electric flocculation effect. Generally speaking, the better the conductivity and corrosion resistance (chemical and electrochemical stability) of the electrode material, the better the electric flocculation technology effect.

[0003] At present, there are relatively few research reports and patents about the preparation of electric flocculation composite electrode materials. In recent years, a research result published in (Chemical Engineering Journal, 2022, 428, 131045) shows that using iron anode and carbon nanotube drum cathode material, under the best conditions, a total organic carbon (TOC) removal rate of up to 97% can be achieved. However, this high removal rate can only be achieved when the electric flocculation is combined with the electric Fenton process, and this coupled process is relatively complex and high in cost, which limits its potential in large-scale application.

[0004] Invention patent CN102092821A entitled Application method of high-performance activated carbon fiber in industrial wastewater treatment by electrocoagulation method, the method uses electrocoagulation method to treat industrial wastewater, uses high-performance activated carbon fiber as electrode, the wastewater treatment efficiency of the invention is high, the application range is wide, the use cost is low, and no secondary pollution is generated. But this method needs to adjust the pH of the wastewater to 3-4 in advance, because the electrode conductivity is poor, the power supply (current, power) requirement is high.

[0005] Chinese patent CN104291415A describes an electrocoagulation method for treating emulsified wastewater using traditional aluminum plate as electrode, under optimized conditions, the chemical oxygen demand (COD) removal rate is high. However, this method does not fully consider the energy consumption of the system, the consumption of the electrode, the passivation and corrosion resistance of the electrode material, etc., which directly affect its feasibility in wide practical application. Therefore, it is an international challenging problem to develop a new type of cathode material to replace the traditional metal cathode material.

[0006] In view of the above problems, the present application provides a preparation method and application of basalt fiber fabric-based electrocoagulation cathode material, which uses basalt fiber fabric as substrate, supplemented by carbon nanotube coating, and silver nanowire as the main conductive coating. The physical contact between the coating and the substrate is crucial to its electrical properties. The introduction of carbon nanotubes promotes the uniform deposition of silver nanowires on the surface of basalt fiber fabric, which pulls the silver atoms at the interface of silver nanowires and carbon nanotubes through van der Waals interaction. SUMMARY

[0007] The present application aims to solve the shortcomings of existing materials and technologies and achieve efficient oil-water separation. The present application provides a preparation method and application of basalt fiber fabric-based electrocoagulation composite cathode material, which immerses basalt fiber fabric in carbon nanotube dispersion liquid first, then coats it in silver nanowire solution, and finally obtains silver nanowire-carbon nanotube-basalt fiber fabric composite cathode material. Basalt fiber is an environmentally friendly and green high-performance fiber material encouraged by the state for development and application, which has high strength, corrosion resistance, high temperature resistance and other excellent properties. The preparation method adopted is simple, efficient, green and environmentally friendly, with low cost, wide application range and suitability for large-scale production. The obtained cathode material is superior to and can replace traditional electrocoagulation metal cathode materials such as aluminum (Al) plate, iron (Fe) plate, magnesium (Mg) plate in terms of electrical conductivity, mechanical strength, chemical stability, corrosion resistance, specific surface area and flexibility. At the same time, the efficiency of electrocoagulation technology for treating oil-containing wastewater is improved, the oil-water separation effect reaches more than 90%, and the application of basalt fiber fabric-based composite materials in important fields of national economy such as electrochemistry, energy electronics, environment and petroleum chemical industry is expanded.

[0008] The preparation method of the basalt fiber fabric-based electroflocculation composite cathode material according to the present application is carried out in the following steps:

[0009] a. Pretreatment of the original basalt fiber fabric: The original basalt fiber fabric is cut into 10*5 cm, and then cleaned with distilled water and ethanol successively, dried at a temperature of 50-80℃ for 20-40 min; the dried basalt fiber fabric is then soaked in a 2 mol / L NaOH solution, placed in an oven at a temperature of 70-90℃, dried for 50-70 min, washed with ultrapure water to remove the residual sodium hydroxide, and dried again in an oven at a temperature of 50-80℃ for 50-70 min;

[0010] b. Preparation of carbon nanotube and silver nanowire dispersion liquid: Carbon nanotubes, cetyltrimethylammonium bromide and sodium alginate are dispersed in distilled water at a mass ratio of 3:1:3, and ultrasonic treatment is performed for 40-70 min to obtain a carbon nanotube dispersion liquid with a concentration of 0.1-0.5 wt%;

[0011] Synthesis of silver nanowires: 0.5-3 g of silver nanowires are dispersed in 100 mL of isopropyl alcohol at a concentration of 0.5-3% w / v, and ultrasonic treatment is performed for 50-70 min to obtain a silver nanowire / isopropyl alcohol dispersion liquid;

[0012] c. Growth of carbon nanotubes on the basalt fiber fabric: The basalt fiber fabric treated in step a is immersed in the carbon nanotube dispersion liquid of step b for 1-3 min, and then dried at a temperature of 40-70℃ for 15-20 min, and this process is repeated for 5 times to obtain a carbon nanotube-basalt fiber fabric CNTs / BF;

[0013] d. Basalt fiber fabric-based electroflocculation composite cathode material AgNws-CNTs / BF: The carbon nanotube-basalt fiber fabric obtained in step c is immersed in the silver nanowire / isopropyl alcohol dispersion liquid of step b, and dried in an oven at a temperature of 50-80℃ until the dispersion liquid is completely evaporated, and uniform deposition of silver nanowires is performed on both sides of the basalt fiber fabric, followed by cleaning with ethanol and ultrapure water, and drying at a temperature of 50-80℃ for 20-40 min to obtain the basalt fiber fabric-based electroflocculation composite cathode material AgNws-CNTs / BF.

[0014] The basalt fiber fabric-based electroflocculation composite cathode material obtained by the method is applied in oil-water separation.

[0015] This invention discloses a method for preparing and applying a basalt fiber fabric-based electrocoagulation cathode material. The method involves immersing basalt fiber fabric in a carbon nanotube (CNT) dispersion for coating, followed by immersion in a self-made silver nanowire (AgNws) solution for coating to form a conductive layer. The resulting composite cathode material exhibits a uniform coating, excellent conductivity, and superior oil-water separation efficiency. It is then applied as a cathode material in an electrocoagulation system for oil-water emulsion separation.

[0016] Silver nanowires were synthesized using silver nitrate (AgNO3) as a precursor, ethylene glycol as a reducing agent and solvent (reducing agents include, but are not limited to, ascorbic acid, glucose, and ethylene glycol), and polyvinylpyrrolidone as a growth control agent.

[0017] Carbon nanotube basalt fiber fabric is immersed in silver nanowire / isopropanol dispersion solution and dried in an oven at 50-80℃ until the dispersion is completely evaporated. This process needs to be carried out on both sides of the basalt fiber fabric to ensure uniform deposition of silver nanowires, thus obtaining a conductive basalt fiber fabric-based cathode. The obtained conductive basalt fiber fabric can be used as a cathode material in electrocoagulation process.

[0018] The application of the basalt fiber fabric-based electrocoagulation cathode material described in this invention in oil-water separation is carried out according to the following steps:

[0019] Preparation of oily wastewater: Pour 700mL of deionized water into a 1000mL dry reagent bottle, dissolve 0.5g of nonionic surfactant Tween 80 in 300mL of deionized water, transfer all of it to the reagent bottle, add 10mL of benzene and 10mL of toluene, stir at 1500 rpm for 12 hours until the solution is mixed evenly.

[0020] Construction of electrocoagulation device: such as Figure 3 As shown, the electrocoagulation device consists of a power source 1, an oil / water emulsion 2, a basalt fiber fabric-based cathode material 3, a magnetic stirrer 4, and an anode material 5. A rectangular acrylic glass reactor containing the oil / water emulsion 2 is placed on the magnetic stirrer 4. The oil-water separation experiment uses a rectangular acrylic glass reactor measuring 10cm × 10cm × 16cm. The aluminum plate 5 of the anode material and the newly developed highly conductive basalt fiber fabric-based cathode electrode material 3 are both 10cm long and 5cm wide. The pH of the solution is adjusted to 7, and 1g of sodium chloride is added to 1000mL of the oil / water emulsion 2. The electrode spacing between the anode material 5 and the basalt fiber fabric-based cathode material 3 is adjusted to 2cm. The applied voltage is 25V, and the experiment lasts for 30min. A chemical oxygen demand (COD) detector is used to evaluate the treatment effect of electrocoagulation on oily wastewater.

[0021] Compared with the prior art, the method provided by the application has the following advantages:

[0022] 1. A certain amount of NaOH is used to pretreat the original basalt fiber fabric, while the chemical and mechanical properties of the basalt fiber fabric base material are retained;

[0023] 2. The transition from insulator (basalt fiber fabric) to conductor, the prepared basalt fiber fabric composite cathode material performs well as an electrocoagulation cathode in oil-water separation. In addition, the method is easy to expand and suitable for large-scale industrial production;

[0024] 3. The application solves the challenging problems of high energy consumption, poor corrosion resistance, and generation of side chemical and electrochemical reactions in the use of traditional metal electrode materials such as Al, Fe, etc.

[0025] 4. By controlling the concentration of silver nanowires to be 0.5%-3% w / v, the conductivity of the composite cathode material is controlled to be between 10 2 -10 4 S / m, as shown in Table 1.

[0026] Table 1: Basalt fiber fabric-based composite cathode material conductivity table

[0027]

[0028] BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 (A) is the original basalt fiber fabric, (B) is the pretreated basalt fiber fabric, (C) is the direct growth of carbon nanotubes on the basalt fiber fabric (CNTs / BF), and (D) is the SEM image of the surface morphology of AgNws-CNT / BF.

[0030] Figure 2 (A) is the original basalt fiber fabric, (B) is the pretreated basalt fiber fabric, (C) is the direct growth of carbon nanotubes on the basalt fiber fabric (CNTs / BF), and (D) is the XRD image of AgNws-CNT / BF.

[0031] Figure 3 (A) is the original basalt fiber fabric, (B) is the pretreated basalt fiber fabric, (C) is the direct growth of carbon nanotubes on the basalt fiber fabric (CNTs / BF), and (D) is the XRD image of AgNws-CNT / BF. DETAILED DESCRIPTION

[0032] In order to make the technical solution of the present application more clear to those skilled in the art, the present application will be described clearly and completely in combination with the embodiments. However, these embodiments do not limit the scope of the present application, and these only represent some embodiments of the present application, but do not cover all possible embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work also belong to the protection scope of the present application.

[0033] It should be noted that, in the following examples, the experimental methods described, unless otherwise specified, are conventional methods; the reagents and materials used, unless otherwise specified, can be purchased in the market.

[0034] Example 1

[0035] a, raw basalt fiber fabric pretreatment: cut the raw basalt fiber fabric into 10*5cm, wash with distilled water and ethanol in turn, dry at 60℃ for 30min; then immerse the dried basalt fiber fabric in 2mol / L NaOH solution, put it into the oven at 90℃, dry for 60min, wash with ultrapure water several times to remove the residual sodium hydroxide, and dry it again in the oven at 60℃ for 50min;

[0036] b, preparation of carbon nanotube and silver nanowire dispersion liquid: disperse carbon nanotube, cetyltrimethylammonium bromide and sodium alginate in distilled water at a mass percentage of 3:1:3, and treat with ultrasonic wave for 40min to obtain a carbon nanotube dispersion liquid with a concentration of 0.5wt%; synthesis of silver nanowire: disperse 0.5g silver nanowire in 100mL isopropanol 0.5%w / v, silver nanowire / isopropanol, and treat with ultrasonic wave for 50min to obtain a silver nanowire / isopropanol dispersion liquid;

[0037] c, growth of carbon nanotube on basalt fiber fabric: immerse the basalt fiber fabric pretreated in step a in the carbon nanotube dispersion liquid in step b for 1min, then dry at 40℃ for 15min, repeat this process 5 times to obtain carbon nanotube-basalt fiber fabric CNTs / BF;

[0038] d, basalt fiber fabric-based electroflocculation composite cathode material (AgNws-CNTs / BF): immerse the carbon nanotube basalt fiber fabric CNTs / BF obtained in step c in the silver nanowire / isopropanol dispersion liquid in step b, dry in a 50℃ oven until the dispersion liquid is completely evaporated, and uniformly deposit silver nanowire on both sides of the basalt fiber fabric, then wash with ethanol and ultrapure water, and dry at 50℃ for 30min to obtain the basalt fiber fabric-based electroflocculation cathode material (AgNws-CNT / BF).

[0039] Conclusion: The average conductivity of the basalt fiber fabric cathode obtained is 5.7 x 10 2 S / m.

[0040] Example 2

[0041] a, raw basalt fiber fabric pretreatment: the raw basalt fiber fabric is cut into 10 x 5 cm, washed with distilled water and ethanol in turn, dried at a temperature of 50°C for 20 min; then the dried basalt fiber fabric is immersed in a 2 mol / L NaOH solution, placed in an oven at a temperature of 70°C, dried for 50 min, washed with ultrapure water to remove residual sodium hydroxide, and dried again in an oven at a temperature of 50°C for 60 min;

[0042] b, preparation of carbon nanotube and silver nanowire dispersion liquid: carbon nanotubes, cetyltrimethylammonium bromide and sodium alginate are dispersed in distilled water at a mass percentage of 3:1:3, and ultrasonic treatment is performed for 50 min to obtain a carbon nanotube dispersion liquid with a concentration of 0.1 wt%; synthesis of silver nanowires: 1 g of silver nanowires is dispersed in 100 mL of isopropyl alcohol 1% w / v, and ultrasonic treatment is performed for 60 min to obtain a silver nanowire / isopropyl alcohol dispersion liquid;

[0043] c, growth of carbon nanotubes on basalt fiber fabric: the basalt fiber fabric pretreated in step a is immersed in the carbon nanotube dispersion liquid in step b for 2 min, then dried at a temperature of 50°C for 18 min, and the process is repeated 5 times to obtain carbon nanotube-basalt fiber fabric CNTs / BF;

[0044] d, basalt fiber fabric-based electroflocculation composite cathode material AgNws-CNTs / BF: the carbon nanotube basalt fiber fabric CNTs / BF obtained in step c is immersed in the silver nanowire / isopropyl alcohol dispersion liquid in step b, dried in a 60°C oven until the dispersion liquid is completely evaporated, and uniform deposition of silver nanowires is performed on both sides of the basalt fiber fabric, followed by cleaning with ethanol and ultrapure water, and drying at a temperature of 70°C for 30 min to obtain the basalt fiber fabric-based electroflocculation cathode material AgNws-CNTs / BF.

[0045] Conclusion: The average conductivity of the basalt fiber fabric cathode material obtained is 1.56 x 10 3 S / m.

[0046] Example 3

[0047] a, raw basalt fabric pretreatment: the raw basalt fabric is cut into 10*5 cm, and is washed with distilled water and ethanol in turn, dried at 80 °C for 40 min; then the dried basalt fabric is immersed in 2 mol / L NaOH solution, placed in an oven at 90 °C, dried for 70 min, washed with ultrapure water for several times to remove residual sodium hydroxide, and dried in an oven at 80 °C for 70 min again;

[0048] b, preparation of carbon nanotube and silver nanowire dispersion liquid: carbon nanotubes, cetyltrimethylammonium bromide and sodium alginate are dispersed in distilled water at a mass ratio of 3:1:3, and ultrasonic treatment is performed for 70 min to obtain a carbon nanotube dispersion liquid with a concentration of 0.5 wt%; synthesis of silver nanowire: 2 g of silver nanowire is dispersed in 100 mL of 2% w / v isopropanol, and ultrasonic treatment is performed for 70 min to obtain a silver nanowire / isopropanol dispersion liquid;

[0049] c, carbon nanotube growth on basalt fabric: the basalt fabric pretreated in step a is immersed in the carbon nanotube dispersion liquid in step b for 3 min, and then dried at 70 °C for 40 min, and the process is repeated for 5 times to obtain a carbon nanotube-basalt fabric CNTs / BF;

[0050] d, basalt fabric-based electroflocculation composite cathode material AgNws-CNTs / BF: the carbon nanotube-basalt fabric CNTs / BF obtained in step c is immersed in the silver nanowire / isopropanol dispersion liquid in step b, and dried in an oven at 80 °C until the dispersion liquid is completely evaporated, and uniform deposition of silver nanowire is performed on both sides of the basalt fabric, followed by cleaning with ethanol and ultrapure water, and drying at 80 °C for 40 min to obtain a basalt fabric-based electroflocculation cathode material.

[0051] Conclusion: the average conductivity of the obtained basalt fabric composite cathode material is 6.43*10 3 S / m.

[0052] Example 4

[0053] a, raw basalt fabric pretreatment: the raw basalt fabric is cut into 10*5 cm, and is washed with distilled water and ethanol in turn, dried at 70 °C for 30 min; then the dried basalt fabric is immersed in 2 mol / L NaOH solution, placed in an oven at 80 °C, dried for 60 min, washed with ultrapure water for several times to remove residual sodium hydroxide, and dried in an oven at 70 °C for 60 min again;

[0054] b. Preparation of carbon nanotube and silver nanowire dispersion: Carbon nanotubes, cetyltrimethylammonium bromide and sodium alginate were dispersed in distilled water at a mass percentage of 3:1:3, and ultrasonic treatment was performed for 50 min to obtain a carbon nanotube dispersion with a concentration of 0.4 wt%; synthesis of silver nanowires: 3 g of silver nanowires were dispersed in 100 mL of isopropyl alcohol at 3% w / v, and ultrasonic treatment was performed for 70 min to obtain a silver nanowire / isopropyl alcohol dispersion;

[0055] c. Growth of carbon nanotubes on basalt fiber fabric: The basalt fiber fabric pretreated in step a was immersed in the carbon nanotube dispersion of step b for 2 min, and then dried at a temperature of 70°C for 20 min, and this process was repeated 5 times to obtain a carbon nanotube-basalt fiber fabric CNTs / BF;

[0056] d. Basalt fiber fabric-based electroflocculation composite cathode material AgNws-CNTs / BF: The carbon nanotube basalt fiber fabric CNTs / BF obtained in step c was immersed in the silver nanowire / isopropyl alcohol dispersion of step b, and dried in an oven at a temperature of 80°C until the dispersion was completely evaporated, and uniform deposition of silver nanowires was performed on both sides of the basalt fiber fabric, followed by cleaning with ethanol and ultrapure water, and drying at 80°C for 40 min to obtain the basalt fiber fabric-based electroflocculation cathode material AgNws-CNTs / BF.

[0057] Conclusion: The average conductivity of the obtained basalt fiber fabric composite cathode material was 1.66 x 10 4 S / m.

[0058] The surface morphology and structure of the prepared material were analyzed, as shown in Figure 1 , Figure 2 .

[0059] Example 5

[0060] Application of basalt fiber fabric-based electroflocculation composite cathode material AgNws-CNTs / BF:

[0061] The sample prepared in Example 4 was selected as the cathode material in the electroflocculation process due to its high conductivity of 1.66 x 10 4 S / m, and the initial concentration of the oil-water emulsion was 23065.33 mg / L. After electroflocculation treatment of the obtained basalt fiber fabric-based electroflocculation composite cathode material for 30 min, the chemical oxygen demand (COD) was reduced to 2247.3 mg / L, achieving a removal rate of 90.2%, and the average energy consumption was 1.28 kWh / kg chemical oxygen demand (COD).

[0062] In summary, the present application provides a simple, efficient and low-cost method for preparing basalt fiber fabric-based electric flocculation composite cathode material, which is suitable for electric flocculation oil-water separation process. The composite cathode material achieves a chemical oxygen demand (COD) removal rate of 90.2% in treating oil-water emulsion, and the energy consumption and material consumption are lower than those of the electric flocculation reactor with traditional metal electrode, and has the advantages of convenient operation, low energy consumption, no corrosion, no pollution and no side chemical reaction.

Claims

1. Application of basalt fiber fabric-based electroflocculation composite cathode material in oil-water separation, characterized in that The following steps are taken: a. Pretreatment of raw basalt fiber fabric: The raw basalt fiber fabric is cut into 10 x 5 cm, washed with distilled water and ethanol in turn, dried at a temperature of 50-80℃ for 20-40 min; then the dried basalt fiber fabric is immersed in a 2 mol / L NaOH solution and placed in an oven at a temperature of 70-90℃ for 50-70 min, washed with ultrapure water to remove residual sodium hydroxide, and then dried in an oven at a temperature of 50-80℃ for 50-70 min; b. Preparation of carbon nanotube and silver nanowire dispersion: Carbon nanotubes, cetyltrimethylammonium bromide, and sodium alginate are dispersed in distilled water at a mass percentage of 3:1:3, and ultrasonic treatment is performed for 40-70 min to obtain a carbon nanotube dispersion with a concentration of 0.1-0.5 wt%; Synthesis of silver nanowires: 0.5-3 g of silver nanowires are dispersed in 100 mL of isopropyl alcohol at a concentration of 0.5-3% w / v, and ultrasonic treatment is performed for 50-70 min to obtain a silver nanowire / isopropyl alcohol dispersion; c. Growth of carbon nanotubes on basalt fiber fabric: The basalt fiber fabric treated in step a is immersed in the carbon nanotube dispersion of step b for 1-3 min, then dried at a temperature of 40-70℃ for 15-20 min, and this process is repeated 5 times to obtain a carbon nanotube-basalt fiber fabric CNTs / BF; d. Basalt fiber fabric-based electrocoagulation composite cathode material AgNws-CNTs / BF: The carbon nanotube-basalt fiber fabric obtained in step c is immersed in the silver nanowire / isopropyl alcohol dispersion of step b, dried in an oven at a temperature of 50-80℃ until the dispersion is completely evaporated, and uniform deposition of silver nanowires is performed on both sides of the basalt fiber fabric, followed by washing with ethanol and ultrapure water, and drying at a temperature of 50-80℃ for 20-40 min to obtain a basalt fiber fabric-based electrocoagulation composite cathode material AgNws-CNTs / BF.

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