Basic knowledge of activated carbon

1. 活性炭分類－由于原料來(lái)源、制造方法、外觀形狀和應(yīng)用場(chǎng)合不同,活性炭品種不下千種。 

1.1 按原料來(lái)源分，可分為木質(zhì)活性炭(如椰殼活性炭、杏殼活性炭、木質(zhì)粉炭等)、 礦物質(zhì)原料活性炭(各種煤和石油及其加工產(chǎn)物為原料制成的活性炭)、其它原料制成的活性炭(如廢橡膠、廢塑料等制成的活性炭)。

1.2 按制造方法分，可分為化學(xué)法活性炭(化學(xué)炭)

      將含碳原料與某些化學(xué)藥品混合后進(jìn)行熱處理，制取活性炭的方法叫化學(xué)法。用化學(xué)法生產(chǎn)的活性炭又稱為化學(xué)法活性炭或化學(xué)炭。

      可以作為化學(xué)法的化學(xué)藥品又稱作活化劑，活化劑有氯化鋅、氯化鈣、碳酸鉀、磷酸、磷酸二氫鉀、硫化鉀、硫酸、氫氧化鉀、氫氧化鈉、硼酸等，總之許多酸、堿、鹽都可以用作活化劑，主要從活性炭的性能和經(jīng)濟(jì)性來(lái)考慮采用何種活化劑。

      一般說(shuō)來(lái)，化學(xué)炭的孔隙中次微孔、中孔（即孔直徑或孔寬大于1.5納米的孔隙）較發(fā)達(dá)，主要用于液相吸附精制和溶劑回收的氣相（蒸汽）吸附場(chǎng)合。 

      化學(xué)法制造活性炭由于加入了化學(xué)藥品在制造過(guò)程中應(yīng)當(dāng)極其重視環(huán)境保護(hù)以及產(chǎn)品中可能存在微量非原料帶入的元素的影響問(wèn)題。

 1.2.2 物理法活性炭

      以炭為原料用水蒸汽、二氧化碳、空氣（主要是氧）或它們的混合物（煙道氣）為活化介質(zhì)，在高溫下（600～1000℃）進(jìn)行活化制取活性炭的方法叫物理法。物理法制造的活性炭叫物理法活性炭，也稱作物理炭。一般說(shuō)來(lái)物理炭的微孔（孔直徑或孔寬小于1.5納米的孔隙）發(fā)達(dá)，主要用于氣相吸附場(chǎng)合或小分子液相吸附場(chǎng)合。

1.2.3 化學(xué)--物理法或物理--化學(xué)法活性炭

      在了解化學(xué)炭和物理炭的同時(shí)，還應(yīng)當(dāng)提及化學(xué)--物理法或物理--化學(xué)法活性炭。選用不同的原料和采用不同的化學(xué)法與物理法的組合可以對(duì)活性炭的孔隙結(jié)構(gòu)進(jìn)行調(diào)控，從而制取許多性能不同的活性炭。這種化學(xué)--物理法或物理--化學(xué)法是許多年來(lái)及今后相當(dāng)長(zhǎng)時(shí)期內(nèi)世界各國(guó)活性炭工作者非常關(guān)注的活性炭制取方法。

1.3 按外觀形狀分

     1.3.1 粉狀活性炭

      一般將90%以上通過(guò)80目標(biāo)準(zhǔn)篩或粒度小于0.175mm的活性炭通稱粉狀活性炭或粉狀炭。粉狀炭在使用時(shí)有吸附速度較快，吸附能力使用充分等優(yōu)點(diǎn)，但需專有的分離方法。隨著分離技術(shù)的進(jìn)步和某些應(yīng)用要求的出現(xiàn)，粉狀炭的粒度有越來(lái)越細(xì)化的傾向，有的場(chǎng)合已達(dá)到微米甚至納米級(jí)。 

      1.3.2 顆�；钚蕴�

      通常把粒度大于0.175mm的活性炭稱作顆粒活性炭。

      顆料活性炭又分為下列幾種。

      1.3.2.1 不定型顆料活性炭

      不定型顆料活性炭一般由顆料狀原料經(jīng)炭化、活化，然后破碎篩分至需要粒度制成，也可以用粉狀活性炭加入適當(dāng)?shù)恼辰Y(jié)劑經(jīng)適當(dāng)加工而成。

      1.3.2.2 園柱形活性炭

      園柱形活性炭又稱柱狀炭，一般由粉狀原料和粘結(jié)劑經(jīng)混捏、擠壓成型再經(jīng)炭化、活化等工序制成。也可以用粉狀活性炭加粘結(jié)劑擠壓成型。柱狀炭又有實(shí)心和中空之分，中空柱狀炭是柱狀炭?jī)?nèi)有人造的一個(gè)或若干個(gè)有規(guī)則的小孔。

      1.3.2.3 球形活性炭

      球形活性炭故名思義是園球形的活性炭，它的制取方法與柱狀炭類似，但有成球過(guò)程。也可以用液態(tài)含碳原料經(jīng)噴霧造粒、氧化、炭化、活化制成，還可以用粉狀活性炭加粘結(jié)劑成球加工而成。球形活性炭也有實(shí)心和空心球形活性炭之分。

      1.3.3 其它形狀的活性炭

      除了粉狀活性炭和顆粒活性炭?jī)纱箢愅猓�還有其他形狀的，如活性炭纖維、活性炭纖維毯、活性炭布、蜂窩狀活性炭、活性炭板等等。

      1.4 按應(yīng)用場(chǎng)合分

      前已述及活性炭廣泛應(yīng)用于幾乎所有國(guó)民經(jīng)濟(jì)部門和人們的日常生活，正因?yàn)槿绱�，按活性炭�?yīng)用場(chǎng)合進(jìn)行分類是很困難的，問(wèn)題在于同一種活性炭可以應(yīng)用于多種場(chǎng)合，而某種場(chǎng)合又可以用多種活性炭達(dá)到相同的目的。人們往往是由應(yīng)用來(lái)獲得對(duì)活性炭的認(rèn)識(shí)的，所以往往在活性炭詞語(yǔ)前冠似×××活性炭也作為的定俗成的活性炭的模糊分類方法。如糖用活性炭、針劑活性炭、味精活性炭、凈水活性炭等等。

      活性炭由于具有吸附、催化和一定的化學(xué)反應(yīng)性能，同時(shí)又具有物理、化學(xué)的相對(duì)穩(wěn)定性。廣泛應(yīng)用于幾乎所有國(guó)民經(jīng)濟(jì)部門和人們的目常生活。

      3.1 活性炭在氣（汽）相吸附中的應(yīng)用

      活性炭在氣（汽）相吸附中的大規(guī)模應(yīng)用是從第一次世界大戰(zhàn)中的毒氣防護(hù)開(kāi)始的。此后，逐漸向其他領(lǐng)域擴(kuò)展，歸納起來(lái)其主要應(yīng)用如下。

      3.1.1 有毒或有害氣體的防護(hù)

      防毒面具、口罩和防護(hù)服是活性炭應(yīng)用的典型代表。

      3.1.2 氣（汽）體的凈化、精制和分離

      空氣凈化、空氣的氮、氧吸附分離和純化；工業(yè)氫的度壓吸附分離和提純；溶劑回收；煙氣中去除二氧化硫和氮氧化合物；空調(diào)；航天和深海潛艇的工作環(huán)境的氣體凈化等部離不開(kāi)活性炭。

      3.2 活性炭在液相吸附中的應(yīng)用

      活性炭最早的應(yīng)用是從歐洲人精制糖液開(kāi)始的�，F(xiàn)在活性炭在液相吸附中的應(yīng)用乙遍及許多工業(yè)部門和人們的日常生活。

      3.2.1 食品工業(yè)中的應(yīng)用

      所有甜味劑、調(diào)味品、食用油脂、飲料都使用活性炭進(jìn)行脫色精制。到目前為止，這方面的應(yīng)用仍然是活性炭最廣闊的市場(chǎng)之一，特別是正在實(shí)現(xiàn)工業(yè)化的我國(guó)和許多發(fā)展中國(guó)家。

      3.2.2 制藥工業(yè)中的應(yīng)用

      所有人工合面和生物制藥的原料藥，尤其是西藥都采用活性炭進(jìn)行脫色精制�；钚蕴课�附的主要作用是去除雜質(zhì)、提高純度和去除致熱源。這是活性炭又一廣大市場(chǎng)之一。

      3.2.3 活性炭在化學(xué)工業(yè)和其他工業(yè)中的應(yīng)用

      活性炭在石化工業(yè)中的油品精制、脫硫、脫臭、催化劑載體；無(wú)機(jī)化工中的含用和醫(yī)藥級(jí)制品的精制提純；治金工業(yè)中特別是濕法冶金中的金、鉑等貴金屬的提取以及染織工業(yè)中的染料、媒染劑等都逐漸使用活性炭，是近幾十年來(lái)活性炭新開(kāi)發(fā)的市場(chǎng)。

      3．3 活性炭在環(huán)境保護(hù)中的應(yīng)用

      活性炭的應(yīng)用中，從上世紀(jì)六、七十年代起環(huán)境保護(hù)逐漸成為活性炭最大的消費(fèi)領(lǐng)域，包括氣、液相吸附的環(huán)保用活性炭往往占發(fā)達(dá)國(guó)家總用量的60%以上。環(huán)保中的氣相處理是各種工業(yè)生活廢氣的凈化和回收有用溶劑。環(huán)保中的液相汲附處理中主要用于人們生活的上、下水和工業(yè)廢水的處理上。發(fā)達(dá)國(guó)家的人們的飲用水、城市生活廢水、工業(yè)廢水基本上都采用包括活性炭處理在內(nèi)的三級(jí)凈化，發(fā)達(dá)國(guó)家用于水處理的活性炭約占其總用量的40～50%。我國(guó)開(kāi)始重視環(huán)境問(wèn)題，預(yù)期不遠(yuǎn)將來(lái)，活性炭在我國(guó)水處理中將獲得躍式的發(fā)展。

      3.4 活性炭在高新技術(shù)領(lǐng)域中的應(yīng)用進(jìn)展

      近二十年來(lái)高新技術(shù)已成國(guó)世界各國(guó)經(jīng)濟(jì)發(fā)展的競(jìng)技物。科技的迅速發(fā)展促進(jìn)了活性炭的發(fā)高比表面、高孔容、高吸附容量的高性能活性炭、超細(xì)活性炭、活性炭各種各樣的制品不斷涌現(xiàn)。而這些活性炭新品系在高新電子電極、新型催化劑截體、電能和高能量密度物質(zhì)（如壓縮或液化氫氣、天然氣等）和貯存。電動(dòng)汽車、功能性綠色環(huán)保等諸多領(lǐng)域的應(yīng)用都屢見(jiàn)有關(guān)文獻(xiàn)，不少已投放市場(chǎng)。我國(guó)的活性炭工作者也在不懈努力，有些方面已取得突破，可以預(yù)期在新世紀(jì)里我國(guó)活性炭在高新技術(shù)領(lǐng)域?qū)⒄加幸幌�之地�?/span>

1. Classification of Activated Carbon - Due to differences in raw material sources, manufacturing methods, appearance forms, and application scenarios, there are no fewer than a thousand types of activated carbon.   1.1 Classified by Raw Material Source   They can be divided into wood-based activated carbon (such as coconut shell activated carbon, apricot shell activated carbon, wood powder carbon, etc.), mineral raw material activated carbon (activated carbon made from various coals, petroleum and their processed products as raw materials), and activated carbon made from other raw materials (such as activated carbon made from waste rubber, waste plastics, etc.).   1.2 Classified by Manufacturing Method   1.2.1 Chemical Method Activated Carbon (Chemical Carbon)   The method of preparing activated carbon by mixing carbon-containing raw materials with certain chemicals and then performing heat treatment is called the chemical method. Activated carbon produced by the chemical method is also known as chemical method activated carbon or chemical carbon.   Chemicals that can be used in the chemical method are also called activators. Activators include zinc chloride, calcium chloride, potassium carbonate, phosphoric acid, potassium dihydrogen phosphate, potassium sulfide, sulfuric acid, potassium hydroxide, sodium hydroxide, boric acid, etc. In short, many acids, alkalis, and salts can be used as activators, and the choice of which activator to use mainly depends on the performance and economy of the activated carbon.   Generally speaking, the mesopores and macropores (pores with a diameter or width greater than 1.5 nanometers) in the pores of chemical carbon are well-developed, and they are mainly used in liquid-phase adsorption refining and gas-phase (vapor) adsorption occasions for solvent recovery.   In the production of activated carbon by the chemical method, due to the addition of chemicals, great attention should be paid to environmental protection during the manufacturing process, as well as the impact of possible trace elements in the product that are not brought in by the raw materials.   1.2.2 Physical Method Activated Carbon   The method of preparing activated carbon by using carbon as the raw material and steam, carbon dioxide, air (mainly oxygen) or their mixtures (flue gas) as the activation medium, and performing activation at high temperatures (600-1000°C) is called the physical method. Activated carbon produced by the physical method is called physical method activated carbon, also known as physical carbon. Generally speaking, the micropores (pores with a diameter or width less than 1.5 nanometers) of physical carbon are well-developed, and they are mainly used in gas-phase adsorption occasions or small-molecule liquid-phase adsorption occasions.   1.2.3 Chemical-Physical Method or Physical-Chemical Method Activated Carbon   While understanding chemical carbon and physical carbon, it is also necessary to mention chemical-physical method or physical-chemical method activated carbon. By selecting different raw materials and using different combinations of chemical and physical methods, the pore structure of activated carbon can be adjusted, thereby producing many types of activated carbon with different properties. This chemical-physical method or physical-chemical method has been and will be a method for preparing activated carbon that has attracted great attention from activated carbon researchers around the world for many years and for a long time to come.   1.3 Classified by Appearance Form   1.3.1 Powdered Activated Carbon   Generally, activated carbon with more than 90% passing through an 80-mesh standard sieve or with a particle size smaller than 0.175mm is commonly referred to as powdered activated carbon or powdered carbon. Powdered carbon has the advantages of fast adsorption speed and full utilization of adsorption capacity during use, but it requires a proprietary separation method. With the advancement of separation technology and the emergence of certain application requirements, the particle size of powdered carbon tends to become more and more refined, and in some cases, it has reached the micron or even nanometer level.   1.3.2 Granular Activated Carbon   Activated carbon with a particle size larger than 0.175mm is usually called granular activated carbon.   Granular activated carbon can be further divided into the following types:   1.3.2.1 Unshaped Granular Activated Carbon   Unshaped granular activated carbon is generally made from granular raw materials through carbonization, activation, then crushing and sieving to the required particle size. It can also be made by adding an appropriate binder to powdered activated carbon and processing it appropriately.   1.3.2.2 Cylindrical Activated Carbon   Cylindrical activated carbon, also known as columnar carbon, is generally made from powdered raw materials and binders through kneading, extrusion molding, then carbonization, activation and other processes. It can also be made by extrusion molding with powdered activated carbon and binders. Columnar carbon can be solid or hollow; hollow columnar carbon has one or several regular small holes artificially made inside.   1.3.2.3 Spherical Activated Carbon   As the name suggests, spherical activated carbon is spherical activated carbon. Its preparation method is similar to that of columnar carbon, but with a pelletizing process. It can also be made from liquid carbon-containing raw materials through spray granulation, oxidation, carbonization, and activation, or from powdered activated carbon with binders through pelletizing. Spherical activated carbon can also be divided into solid and hollow spherical activated carbon.   1.3.3 Activated Carbon of Other Shapes   In addition to the two major categories of powdered activated carbon and granular activated carbon, there are other shapes, such as activated carbon fiber, activated carbon fiber blanket, activated carbon cloth, honeycomb activated carbon, activated carbon plate, etc.   1.4 Classified by Application Scenario   As mentioned earlier, activated carbon is widely used in almost all national economic sectors and people's daily lives. Because of this, it is very difficult to classify activated carbon according to its application scenarios. The problem is that the same type of activated carbon can be used in multiple scenarios, and a certain scenario can also use multiple types of activated carbon to achieve the same purpose. People often gain an understanding of activated carbon through its applications, so they often prefix the term "activated carbon" with a modifier (e.g., sugar-use activated carbon, injection-use activated carbon, monosodium glutamate-use activated carbon, water purification activated carbon, etc.) as a customary vague classification method for activated carbon.   Activated carbon has adsorption, catalytic, and certain chemical reaction properties, as well as relative physical and chemical stability. It is widely used in almost all national economic sectors and people's daily lives.   3.1 Application of Activated Carbon in Gas (Vapor) Phase Adsorption   The large-scale application of activated carbon in gas (vapor) phase adsorption began with gas protection during World War I. Since then, it has gradually expanded to other fields. To summarize, its main applications are as follows:   3.1.1 Protection Against Toxic or Harmful Gases   Gas masks, face masks, and protective clothing are typical examples of the application of activated carbon.   3.1.2 Purification, Refining, and Separation of Gases (Vapors)   Air purification, adsorption separation and purification of nitrogen and oxygen in air; pressure swing adsorption separation and purification of industrial hydrogen; solvent recovery; removal of sulfur dioxide and nitrogen oxides from flue gas; air conditioning; gas purification in the working environments of aerospace and deep-sea submarines, etc., all rely on activated carbon.   3.2 Application of Activated Carbon in Liquid Phase Adsorption   The earliest application of activated carbon started with the refining of sugar solutions by Europeans. Now, the application of activated carbon in liquid phase adsorption has spread to many industrial sectors and people's daily lives.   3.2.1 Application in the Food Industry   All sweeteners, condiments, edible oils, and beverages use activated carbon for decolorization and refining. So far, this application remains one of the largest markets for activated carbon, especially in China and many developing countries that are undergoing industrialization.   3.2.2 Application in the Pharmaceutical Industry   All raw materials for artificial synthesis and biopharmaceuticals, especially western medicines, use activated carbon for decolorization and refining. The main role of activated carbon adsorption is to remove impurities, improve purity, and remove pyrogens. This is another large market for activated carbon.   3.2.3 Application of Activated Carbon in the Chemical Industry and Other Industries   In the petrochemical industry, activated carbon is used for oil product refining, desulfurization, deodorization, and as a catalyst carrier; in the inorganic chemical industry, it is used for the refining and purification of industrial and pharmaceutical-grade products; in the metallurgical industry, especially in hydrometallurgy, it is used for the extraction of precious metals such as gold and platinum; and in the dyeing and weaving industry, it is used for dyes, mordants, etc. These are newly developed markets for activated carbon in recent decades.   3.3 Application of Activated Carbon in Environmental Protection   In the application of activated carbon, environmental protection has gradually become the largest consumption field of activated carbon since the 1960s and 1970s. Activated carbon used for environmental protection in gas and liquid phase adsorption often accounts for more than 60% of the total consumption in developed countries. The gas-phase treatment in environmental protection involves the purification of various industrial and domestic waste gases and the recovery of useful solvents. The liquid-phase adsorption treatment in environmental protection is mainly used for the treatment of domestic water, sewage, and industrial wastewater. In developed countries, domestic drinking water, urban domestic wastewater, and industrial wastewater are basically treated with tertiary purification including activated carbon treatment. Activated carbon used for water treatment in developed countries accounts for about 40-50% of their total consumption. China has begun to attach importance to environmental issues, and it is expected that in the near future, the application of activated carbon in water treatment in China will achieve leapfrog development.   3.4 Application Progress of Activated Carbon in High-Tech Fields   In the past 20 years, high technology has become a key area for economic development in countries around the world. The rapid development of science and technology has promoted the development of activated carbon. High-performance activated carbon with high specific surface area, high pore volume, and high adsorption capacity, ultra-fine activated carbon, and various products of activated carbon are constantly emerging. These new types of activated carbon have been frequently mentioned in the literature for their applications in many fields such as high-tech electronic electrodes, new catalyst carriers, storage of electrical energy and high-energy-density substances (such as compressed or liquefied hydrogen, natural gas, etc.), electric vehicles, and functional green environmental protection. Many of them have been put on the market. Chinese researchers of activated carbon are also making unremitting efforts, and breakthroughs have been made in some aspects. It is expected that China's activated carbon will occupy a place in the high-tech field in the new century.