A kind of hydrophobic activated carbon fiber felt and preparation method thereof

Abstract

The present invention discloses a hydrophobic activated carbon fiber felt and a preparation method thereof, comprising an activated carbon fiber felt and a porous hydrophobic layer wrapped around the outer fiber wall of the activated carbon fiber felt. The hydrophobic activated carbon fiber felt is characterized in that the porous hydrophobic layer wrapped around the outer fiber wall of the activated carbon fiber felt is prepared by a process of fiber flame retardant and hydrophobic treatment, needle punching into felt, pre-oxidation, and carbonization activation treatment. The hydrophobic layer has a certain thickness. The preparation process of the hydrophobic activated carbon fiber felt includes the following materials: viscose fiber, a hydrophobic agent, a flame retardant, and water vapor. Compared with the existing technology of post-hydrophobic treatment, the preparation method of the activated carbon fiber felt has improved hydrophobic performance and firmness. At the same time, the process adopts a process of direct flame retardant and hydrophobic treatment of the fiber, which improves the uniformity of the treatment and production efficiency. The product quality is significantly improved, the specific surface area is large, the strength is high, the ignition point is high, the hydrophobicity is strong, and the adsorption force on VOCs is enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of carbon fibers, in particular to a hydrophobic activated carbon fiber felt and a preparation method thereof. Background Art

[0002] Activated carbon fiber is an activated carbon fiber. A certain carbon fiber (such as phenolic-based fiber, PAN-based fiber, viscose-based fiber, asphalt-based fiber, etc.) is activated at high temperature (different activation methods have different activation temperatures) to produce nano-scale pores on its surface, increase the specific surface area, and thus change its physical and chemical properties. Activated carbon fiber has a large specific surface area (1000-3000m2 / g) and abundant micropores, with the micropore volume accounting for more than 90% of the total pore volume. Activated carbon fiber has a larger adsorption capacity and faster adsorption kinetics than granular activated carbon. It has high adsorption efficiency for organic matter and anions and cations in liquid and gas phases, fast adsorption and desorption rates, and can be recycled. It is also resistant to acid, alkali, high temperature, strong adaptability, good conductivity and chemical stability. It is an ideal environmentally friendly material that can selectively adsorb pollutants in gas or aqueous solution. The activated carbon fiber after use also has good reproducibility, making ACF (activated carbon fiber) and its deep-processed products widely used in the field of environmental purification. At present, it has been widely used in the purification of gas, water and organic solvent recovery.

[0003] Activated carbon or activated carbon fibers have problems with poor selectivity and water resistance when adsorbing dichloromethane. In response to existing technical problems, the preparation method of activated carbon fiber felt provided by the present invention improves the hydrophobicity and firmness compared with the existing technology of subsequent hydrophobic treatment, and increases the adsorption efficiency of dichloromethane; at the same time, this process adopts the process of direct flame retardant and hydrophobic treatment of the fibers, which improves the uniformity of the treatment and the production efficiency, and significantly improves the product quality. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the present invention provides a hydrophobic activated carbon fiber felt and a preparation method thereof, which solves the technical problems of poor selectivity and water resistance of the existing activated carbon fiber felt when adsorbing dichloromethane.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: a hydrophobic activated carbon fiber felt, comprising an activated carbon fiber felt and a porous hydrophobic layer wrapped around the fiber outer wall of the activated carbon fiber felt, the porous hydrophobic layer wrapped around the fiber outer wall of the activated carbon fiber felt is prepared by a process of fiber flame retardant and hydrophobic treatment, needle punching into felt, pre-oxidation, and carbonization activation treatment, the hydrophobic layer has a certain thickness, and the preparation process of the hydrophobic activated carbon fiber felt includes the following materials: viscose fiber, hydrophobic agent, flame retardant, and water vapor.

[0006] A method for preparing hydrophobic activated carbon fiber felt, the method comprising the following steps:

[0007] S1: Viscose fiber diameter is 1.33dtex to 13.3dtex or one or more diameter specifications are mixed in proportion;

[0008] S2: The ratio of viscose fiber, flame retardant and hydrophobic agent can be reasonably adjusted;

[0009] S3: The pre-oxidation temperature of activated carbon fiber felt is 150~400℃, and the carbonization activation temperature of activated carbon fiber felt is 800~1200℃;

[0010] S4: Activated carbon fiber felt can be made of viscose fiber or other bio-based and synthetic fibers.

[0011] Preferably, the hydrophobic agent is sodium silicate or silicon dioxide, and the flame retardant is diammonium hydrogen phosphate or ammonium dihydrogen phosphate.

[0012] Preferably, the water vapor is saturated water vapor or superheated steam.

[0013] Preferably, the hydrophobic layer attached to the outer wall of the activated carbon fiber felt has a thickness of 15 to 120 nm.

[0014] Preferably, the concentration of the hydrophobic agent is 0.1%∽5%.

[0015] Preferably, the flame retardant concentration is 2%∽15%, and the water vapor pressure is 2bar∽8bar. Beneficial effects

[0016] The present invention provides a hydrophobic activated carbon fiber and a method for preparing the same. Compared to existing methods that require post-hydrophobic treatment, the method improves hydrophobicity and durability of the activated carbon fiber felt. Furthermore, the process employs direct flame retardancy and hydrophobic treatment of the fibers, enhancing treatment uniformity and production efficiency. This significantly improves product quality, resulting in a large specific surface area, high strength, a high flash point, strong hydrophobicity, and enhanced VOC adsorption. The activation process utilizes only water vapor, eliminating the need for other inert gases, thereby reducing production costs. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0018] The present invention provides a technical solution: a hydrophobic activated carbon fiber felt, comprising an activated carbon fiber felt and a porous hydrophobic layer wrapped around the fiber outer wall of the activated carbon fiber felt, wherein the porous hydrophobic layer wrapped around the fiber outer wall of the activated carbon fiber felt is prepared by a process of fiber flame retardant and hydrophobic treatment, needle punching into felt, pre-oxidation, and carbonization activation treatment, wherein the hydrophobic layer has a certain thickness, and the preparation process of the hydrophobic activated carbon fiber felt includes the following materials: viscose fiber, a hydrophobic agent, a flame retardant, and water vapor.

[0019] A method for preparing hydrophobic activated carbon fiber felt, the method comprising the following steps:

[0020] S1: Viscose fiber diameter is 1.33dtex to 13.3dtex or one or more diameter specifications are mixed in proportion;

[0021] S2: The ratio of viscose fiber, flame retardant and hydrophobic agent can be reasonably adjusted;

[0022] S3: The pre-oxidation temperature of activated carbon fiber felt is 150~400℃, and the carbonization activation temperature of activated carbon fiber felt is 800~1200℃;

[0023] S4: Activated carbon fiber felt can be made of viscose fiber or other bio-based and synthetic fibers.

[0024] This embodiment is further configured such that the hydrophobic agent is sodium silicate or silicon dioxide, and the flame retardant is diammonium hydrogen phosphate or ammonium dihydrogen phosphate.

[0025] This embodiment is further configured such that the water vapor is saturated water vapor or superheated steam.

[0026] This embodiment is further configured such that the hydrophobic layer attached to the outer wall of the activated carbon fiber felt has a thickness of 15 to 120 nm.

[0027] This embodiment is further configured such that the concentration of the hydrophobic agent is 0.1%∽5%.

[0028] This embodiment is further configured such that the flame retardant concentration is 2%∽15%, and the water vapor pressure is 2 bar∽8 bar.

[0029] The detailed connection means are well-known technologies in this field. The following mainly introduces the working principle and process. The specific work is as follows.

[0030] Examples: (1) Flame retardant and silicon-based hydrophobic agent impregnation pretreatment: Using viscose fiber felt as raw material, the raw material is sprayed and impregnated with diammonium hydrogen phosphate and sodium silicate solutions of different concentrations in an impregnation production line for multiple times, squeezed for dehydration, and dried; (2) Needle punching: The fiber treated in (1) is needled into a needle-punched felt of the required specifications through a needle-punching machine and rolled for standby use; (3) Pre-oxidation: The needle-punched felt is unrolled, flattened, and continuously put into a pre-oxidation furnace for pre-oxidation to form a pre-oxidized felt with a heat-resistant structure; (4) Carbonization and activation: The pre-oxidized felt body is continuously placed in an activation furnace passing through superheated steam to complete the carbonization and activation processes at the same time, and after cooling out of the furnace, a hydrophobic activated carbon fiber felt is obtained.

[0031] The specific surface area of ​​the same weight prepared by this process is 1280m 2 / g hydrophobic activated carbon fiber felt and ordinary activated carbon fiber felt without hydrophobic agent (control group) were compared at a temperature of 25 ° C and a concentration of 3500 mg / m 3 The saturated adsorption capacity of dichloromethane under different relative humidity conditions was compared, and the results are shown in the following table:

[0032] Under dry conditions RH=50% RH=75% RH=95% Saturated adsorption capacity of hydrophobic activated carbon fiber felt (mg / g) 608 582 553 519 Saturated adsorption capacity of the control group (mg / g) 610 541 487 410

[0033] It is concluded that the hydrophobic activated carbon fiber felt exhibits different adsorption capacities under different humidity environments, and the saturated adsorption capacity is basically the same under dry conditions, with an 11% increase at RH50%, a 13.5% increase at RH75%, and a 26.5% increase at RH95%. Based on the experiment, it is concluded that the preparation method of hydrophobic activated carbon fiber felt has improved hydrophobic performance and firmness compared with the existing technology of post-hydrophobic treatment. At the same time, this process adopts the process of direct flame retardant and hydrophobic treatment of fibers, which improves the uniformity of treatment and production efficiency, and the product quality is significantly improved, with high strength, high ignition point, strong hydrophobicity, and enhanced adsorption of VOCs.

[0034] It should be noted that, in this document, relational terms such as first and second, etc. are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.

Claims

1. A hydrophobic activated carbon fiber felt, comprising an activated carbon fiber felt and a porous hydrophobic layer wrapped around the outer fiber wall of the activated carbon fiber felt, characterized in that: The porous hydrophobic layer wrapped around the outer wall of the activated carbon fiber felt is prepared by a process of fiber flame retardant and hydrophobic treatment, needle punching into felt, pre-oxidation, and carbonization activation treatment. The hydrophobic layer has a certain thickness. The preparation process of the hydrophobic activated carbon fiber felt includes the following materials: viscose fiber, hydrophobic agent, flame retardant, and water vapor; Wherein, the hydrophobic agent is hydrophobic sodium silicate or hydrophobic silicon dioxide, and the flame retardant is diammonium hydrogen phosphate or ammonium dihydrogen phosphate.

2. A hydrophobic activated carbon fiber felt according to claim 1, characterized in that , as described: The diameter of viscose fiber ranges from 1.33dtex to 13.3dtex; The pre-oxidation temperature of activated carbon fiber felt is 150~400℃, and the carbonization activation temperature of activated carbon fiber felt is 800~1200℃; Activated carbon fiber felt is prepared using viscose fiber.

3. The hydrophobic activated carbon fiber felt according to claim 1, characterized in that , the water vapor is saturated water vapor or superheated steam.

4. The hydrophobic activated carbon fiber felt according to claim 1, characterized in that The thickness of the hydrophobic layer attached to the outer wall of the activated carbon fiber felt is 15~120nm.

5. The hydrophobic activated carbon fiber felt according to claim 1, characterized in that , the concentration of the hydrophobic agent is 0.1%∽5%.

6. The hydrophobic activated carbon fiber felt according to claim 3, characterized in that , the flame retardant concentration is 2%∽15%, and the water vapor pressure is 2bar∽8bar.