阅读说明：本技术 一种活性炭表面含氧官能团选择性还原方法 (Selective reduction method for oxygen-containing functional groups on surface of activated carbon ) 是由 李新勇 甘国强 王亮 范诗迎 王婧 张祎曼 郭学成 于 2020-04-09 设计创作，主要内容包括：一种活性炭表面含氧官能团选择性还原方法,以活性炭为反应物,以水为溶剂,以二氧化硫脲、硼氢化钠、抗坏血酸中的一种或几种为还原剂,碱性条件下,于30-150℃进行还原反应。本发明可通过调节还原剂的种类以及还原条件选择性的去除活性炭表面含氧官能团,得到不同还原程度的活性炭,满足不同需求,适应活性炭应用的多样性要求。同时,本发明采用的还原剂成本低、无毒、环境友好,并且该方法工艺操作简单、效率高、无需复杂设备,适合工业实际应用。(A selective reduction method of oxygen-containing functional groups on the surface of activated carbon takes activated carbon as a reactant, water as a solvent, one or more of thiourea dioxide, sodium borohydride and ascorbic acid as a reducing agent, and performs reduction reaction at 30-150 ℃ under an alkaline condition. The method can selectively remove oxygen-containing functional groups on the surface of the activated carbon by adjusting the type of the reducing agent and the reduction conditions to obtain the activated carbon with different reduction degrees, meet different requirements and adapt to the diversity requirements of the application of the activated carbon. Meanwhile, the reducing agent adopted by the method is low in cost, non-toxic and environment-friendly, and the method is simple in process operation, high in efficiency, free of complex equipment and suitable for industrial practical application.)

1. A selective reduction method of oxygen-containing functional groups on the surface of activated carbon is characterized in that: taking activated carbon as a reactant, taking water as a solvent, taking one or more of thiourea dioxide, sodium borohydride and ascorbic acid as a reducing agent, and carrying out reduction reaction at 30-150 ℃ under an alkaline condition.

2. The method for selectively reducing oxygen-containing functional groups on the surface of activated carbon according to claim 1, wherein: the pH value of the alkaline condition is 9-14.

3. The method for selectively reducing oxygen-containing functional groups on the surface of activated carbon according to claim 1, wherein: the time of the reduction reaction is 6-24 h.

4. The method for selectively reducing oxygen-containing functional groups on the surface of activated carbon according to claims 1 to 3, wherein the method comprises the following steps:

1) dissolving the reducing agent in deionized water to obtain a reducing agent solution, and adding NaOH to adjust the pH value;

2) adding granular activated carbon into the reducing agent solution with the adjusted pH value to obtain a mixture, and transferring the mixture into a reaction kettle for reaction;

3) after the reaction is finished, filtering to obtain reduced active carbon, washing the reduced active carbon to be neutral by deionized water, drying in vacuum, drying and storing.

5. The method for selectively reducing oxygen-containing functional groups on the surface of activated carbon according to claim 4, wherein: the concentration of the reducing agent solution is 0.01-1.0M.

Technical Field

The invention belongs to the technical field of active carbon material modification, and particularly relates to a selective reduction method for oxygen-containing functional groups on the surface of active carbon.

Background

The activated carbon material is paid much attention due to its excellent physicochemical properties, and is widely used in various industries such as chemical industry and environment. Especially in the field of prevention and treatment of pollution of Volatile Organic Compounds (VOCs) in the atmosphere, activated carbon adsorption is currently the most effective and simple process. However, the surface of the activated carbon material contains a large amount of oxygen-containing functional groups, including hydroxyl, epoxy, carbonyl, carboxyl and the like, which not only make the activated carbon hydrophilic, but also cause bacteria and mildew due to the adsorption of a large amount of water in a humid environment, reduce the service life of the activated carbon, and seriously affect the adsorption performance of the activated carbon. Therefore, the removal of the oxygen-containing functional groups on the surface of the activated carbon has important significance for the application of the activated carbon in the field of VOCs adsorption.

There are two main methods for removing oxygen-containing functional groups on the surface of activated carbon. One of them is that a layer of hydrophobic substance is loaded on the surface of active carbon, and the oxygen-containing functional group is wrapped in the inner layer. The method has good effect, and can greatly reduce oxygen-containing functional groups on the surface, but the method is easy to cause the blockage of the pore channel of the activated carbon, so that the specific surface area is obviously reduced, and the adsorption capacity of the material is further influenced. The second one is that reducing agent and oxygen-containing functional group on the surface are used to produce redox reaction, so as to remove the oxygen-containing functional group on the surface and repair the carbon atom arrangement structure on the surface. The reduction method not only has small influence on the structure of the material, can obviously improve the surface chemical property of the activated carbon on the basis of keeping the microstructure of the activated carbon, but also can select different reducing agents according to the requirement, change the reduction condition and achieve the effect of selective reduction. At present, relatively few reports are reported on the reduction of oxygen-containing functional groups on the surface of activated carbon, and meanwhile, the research on achieving the selective reduction effect is few.

Disclosure of Invention

The invention aims to provide a selective reduction method for oxygen-containing functional groups on the surface of activated carbon, which can selectively remove the oxygen-containing functional groups on the surface of the activated carbon according to different reducing agents and reducing conditions, and is simple in process, low in cost and environment-friendly. The surface hydrophobicity of the activated carbon is changed by adjusting the amount of the oxygen-containing functional groups on the surface, so that the use of the activated carbon in a high-humidity environment is possible.

The invention adopts thiourea dioxide, sodium borohydride and ascorbic acid with different reducibility as reducing agents, and establishes a selective reduction method for oxygen-containing functional groups on the surface of active carbon by optimizing reduction conditions.

The technical scheme of the invention is as follows:

a selective reduction method of oxygen-containing functional groups on the surface of activated carbon takes activated carbon as a reactant, water as a solvent, one or more of thiourea dioxide, sodium borohydride and ascorbic acid as a reducing agent, and performs reduction reaction at 30-150 ℃ under an alkaline condition. The surface of the activated carbon contains oxygen-containing functional groups such as C-O, C-O-C, C ═ O and O-C ═ O.

Based on the scheme, preferably, the concentration of the reducing agent in the solvent is 0.01-1.0M.

Based on the scheme, preferably, the pH value of the alkaline condition is 9-14.

Based on the scheme, preferably, the time of the reduction reaction is 6-24 h.

Based on the above scheme, preferably, the method comprises the following steps:

1) dissolving the reducing agent in deionized water to obtain a reducing agent solution, and adding NaOH to adjust the pH value;

2) adding granular activated carbon into the reducing agent solution with the adjusted pH value to obtain a mixture, and transferring the mixture into a reaction kettle for reaction;

3) after the reaction is finished, filtering to obtain reduced active carbon, washing the reduced active carbon to be neutral by deionized water, drying in vacuum, drying and storing.

Based on the scheme, the concentration of the reducing agent solution is preferably 0.01-1.0M.

The selective reduction mechanism of the oxygen-containing functional groups on the surface of the activated carbon is as follows: the oxygen-containing functional group on the surface of the activated carbon and a reducing agent are subjected to redox reaction, so that the oxygen-containing functional group is removed; different oxygen-containing functional groups have different reactivity, and meanwhile, the type of the reducing agent, the pH value of the solution, the reaction temperature and the reaction time all influence the removal effect of the functional groups, and different types of oxygen-containing functional groups can be selectively removed by controlling the type of the reducing agent and the reaction conditions.

Compared with the prior art, the invention has the following advantages:

(1) the method can selectively reduce and remove oxygen-containing functional groups on the surface of the activated carbon according to different requirements, and can meet the diversity requirements of the application of the activated carbon.

(2) The reducing agent adopted by the invention has low cost, no toxicity and environmental protection, and is suitable for industrial practical application.

(3) The method has the advantages of simple process operation, high efficiency and no need of complex equipment.

Detailed Description

The present invention is described in detail below with reference to examples, which are only for the understanding of the present invention and should not be construed as specifically limiting the present invention.