**1. Historic perspective**

Carbon is the main element of the entire world's flora, and its atomic structure allows unique bonding possibilities leading to various structures with distinct properties. As consequence, carbon materials are used for so long that it is hard to determine the very first moment.

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At the beginning, carbon was used in the form of charcoal that consists of carbonized wood, coal or partially devolatilized coals, and also carbon black obtained by incomplete burning of vegetable oil. After centuries of use of these man-made forms of carbon, the discovery of the processes to perform the activation of charcoal allowed to greatly improve the properties and performances of carbon materials. These new materials where pores (voids) are enclosed by carbon atoms are known as activated carbons or active carbons and, more recently, also named as nanoporous carbons.

of charcoal for decolorizing sugar-beet liquor contributing for the growth of this industry in France [9]. In 1808, all European sugar refineries were using charcoal as a decolorizer [9]. The discovery of bone-derived char as a more efficient raw sugar syrups decolorizing agent was made by Figuier in 1811, and quickly the sugar industry replaced wood charcoal by this improved material [5, 9]. The regeneration of bone-derived char by heating was discovered in 1811, and sometime later granular bone-derived char started to be produced, thus enabling an easier regeneration [9]. In 1815, the majority of sugar refining facilities were using granular bone-derived char [9]. The dependence of the decolorizing properties on the char's source, the thermal processing and particle size was demonstrated by Bussy in 1822 [9]. He also produced a carbon material with higher decolorizing ability than bone-derived char by heating blood with potash, being this the first recorded example of an "activated carbon" material

Nanoporous Carbon Synthesis: An Old Story with Exciting New Chapters

http://dx.doi.org/10.5772/intechopen.72476

39

The first large-scale application in gas phase took place in 1854 [8], with the installation of carbon filters in London sewage ventilation systems. In 1872, carbon filters were also used in the masks of the chemical industry workers for preventing the inhalation of mercury vapors. Besides thousands of years of history, and the already large range of applications for charcoals, it was only in the beginning of the twentieth century that one of the most outstanding abilities of carbon materials was explored: the possibility of enclosing a huge porosity into the carbon material structure. This "revolution" was due to the discoveries of Raphael von Ostrejko that, between 1900 and 1903, patented two different methods for the industrial activation of charcoal and the production of activated carbon materials [10]. This set of patents mentions the bases of the chemical activation process (carbonization of lignocellulosic materials with metallic chlorides) and of the thermal or physical activation (slight gasification of chars with water vapor or carbon dioxide at elevated temperatures) and also the specific equipment for thereof. The factory for full-scale activated carbon production was built by that time in Ratibor, now named Raciborz (Poland), and still operates, being so the world's oldest

Although sugar industry was the first to apply activated carbons, in this case for whitening purposes, the starting point for the great development in the production and application of activated carbons was undoubtedly World War I, when these materials were used in gas masks [7, 8]. The production and search for new activated carbons has been boosted decade after decade due to their fundamental role in various technological applications which are related to, namely, restricted environmental regulations, recovery of valuable chemical com-

Nowadays, the driving forces for the research in nanoporous carbons are related with the properties of the most recent carbon materials: fullerenes [15], carbon nanotubes [16] and graphene [17]. However, the excellent properties of these novel carbon forms also fostered the interest in the traditional porous carbons and, in the recent years, a considerable number of studies searching for new synthetic approaches have been published. The main objective is the preparation of highly porous materials with controlled porosity, and often also with tuned surface chemistry, to present enhanced behavior as, for example, electrode materials

obtained by thermal and chemical processes [5, 9].

industrial activated carbon manufacturing plant [10, 11].

pounds, and catalysts support [8, 12–14].

for supercapacitors.

The oldest known man-made carbon forms—charcoal and carbon black—were used in the Stone Age as a black color pigment for cave painting [1]. For example, charcoal was used as color pigment to draw the black lines of the illustrations in the Cave of Altamira (Spain) that represents the apogee of Paleolithic cave painting art developed across Europe, from 35,000 to 11,000 BC. At about 8,000 BC, charcoal was used in metal production [1]. In 3,750 BC, the Egyptians and Sumerians used it in the reduction of copper, tin, and zinc minerals in the bronze manufacturing process and also as smokeless fuel [2–4]. The first proof of the medicinal use of carbons was found in an Egyptian papyrus, dated of 1,550 BC, where it is reported the use of charcoal for the adsorption of odors from putrefying wounds and also to treat problems of the intestinal tract [5, 6]. The therapeutic value of carbon was later explored by the Greeks (Hippocrates, ca. 460–370 BC) and Romans (Pliny the Elder, AD 23–79) in the treatment of various diseases, including food poisoning, epilepsy, chlorosis, and anthrax [1, 7]. Hippocrates also recommended that the water should be filtered with carbonized wood before its consumption, so as to eliminate bad flavor and odor [8]. Also, Hindu documents from 450 BC mention the use of sand and charcoal filters for drinking water purification [5, 6]. Recent studies also concluded that in Phoenicians ships (460 BC) drinking water was stored in carbonized wood barrels to keep it fresh, a practice that was continued until the eighteenth century. In 157 AD, a medical treatise from Claudius Galvanometer indicated the use of carbons of both vegetable and animal origin for the treatment of various diseases [9]. A Sanskrit document (AD 200) recommended that after being stored in copper vessels and exposed to sunlight, water should be filtrated with coal [6]. This is most probably one of the earliest manuscripts describing the degradation of contaminants from water to assure its disinfection.

It was only during the eighteenth century that the mechanisms underlying the properties of charcoals started to be recognized. In 1773, Scheele measured the adsorptive properties of charcoals from distinct sources using various gases; a decade later, Lowitz studied the abilities of charcoals to adsorb odors from wounds [7, 9]. This author published results regarding the adsorption of a range of organic vapors and also studied systematically the adsorption in various aqueous solutions, namely in the decolorization of contaminated tartaric acid solutions. The discussion of the contribution of charcoals to control odors from gangrenous ulcers was made by Kehl, in 1793, who also discovered that charcoal from animal origin (animal tissues) could be used to remove color from solution, including from sugar solutions [7, 9]. The introduction of carbon materials in industrial processes took place in England, in 1794, when wood charcoals were applied as bleaching agents in the processing of sugar. By that time, the method for preparing the wood charcoals was kept a secret [9]. In 1805, the first large-scale sugar refining facility was introduced in France by Gruillon, working with ground and washed wood char [9]. Between 1805 and 1808, Delessert demonstrated the effectiveness of charcoal for decolorizing sugar-beet liquor contributing for the growth of this industry in France [9]. In 1808, all European sugar refineries were using charcoal as a decolorizer [9]. The discovery of bone-derived char as a more efficient raw sugar syrups decolorizing agent was made by Figuier in 1811, and quickly the sugar industry replaced wood charcoal by this improved material [5, 9]. The regeneration of bone-derived char by heating was discovered in 1811, and sometime later granular bone-derived char started to be produced, thus enabling an easier regeneration [9]. In 1815, the majority of sugar refining facilities were using granular bone-derived char [9]. The dependence of the decolorizing properties on the char's source, the thermal processing and particle size was demonstrated by Bussy in 1822 [9]. He also produced a carbon material with higher decolorizing ability than bone-derived char by heating blood with potash, being this the first recorded example of an "activated carbon" material obtained by thermal and chemical processes [5, 9].

At the beginning, carbon was used in the form of charcoal that consists of carbonized wood, coal or partially devolatilized coals, and also carbon black obtained by incomplete burning of vegetable oil. After centuries of use of these man-made forms of carbon, the discovery of the processes to perform the activation of charcoal allowed to greatly improve the properties and performances of carbon materials. These new materials where pores (voids) are enclosed by carbon atoms are known as activated carbons or active carbons and, more recently, also

The oldest known man-made carbon forms—charcoal and carbon black—were used in the Stone Age as a black color pigment for cave painting [1]. For example, charcoal was used as color pigment to draw the black lines of the illustrations in the Cave of Altamira (Spain) that represents the apogee of Paleolithic cave painting art developed across Europe, from 35,000 to 11,000 BC. At about 8,000 BC, charcoal was used in metal production [1]. In 3,750 BC, the Egyptians and Sumerians used it in the reduction of copper, tin, and zinc minerals in the bronze manufacturing process and also as smokeless fuel [2–4]. The first proof of the medicinal use of carbons was found in an Egyptian papyrus, dated of 1,550 BC, where it is reported the use of charcoal for the adsorption of odors from putrefying wounds and also to treat problems of the intestinal tract [5, 6]. The therapeutic value of carbon was later explored by the Greeks (Hippocrates, ca. 460–370 BC) and Romans (Pliny the Elder, AD 23–79) in the treatment of various diseases, including food poisoning, epilepsy, chlorosis, and anthrax [1, 7]. Hippocrates also recommended that the water should be filtered with carbonized wood before its consumption, so as to eliminate bad flavor and odor [8]. Also, Hindu documents from 450 BC mention the use of sand and charcoal filters for drinking water purification [5, 6]. Recent studies also concluded that in Phoenicians ships (460 BC) drinking water was stored in carbonized wood barrels to keep it fresh, a practice that was continued until the eighteenth century. In 157 AD, a medical treatise from Claudius Galvanometer indicated the use of carbons of both vegetable and animal origin for the treatment of various diseases [9]. A Sanskrit document (AD 200) recommended that after being stored in copper vessels and exposed to sunlight, water should be filtrated with coal [6]. This is most probably one of the earliest manuscripts describing the degradation of contaminants from water to assure its disinfection. It was only during the eighteenth century that the mechanisms underlying the properties of charcoals started to be recognized. In 1773, Scheele measured the adsorptive properties of charcoals from distinct sources using various gases; a decade later, Lowitz studied the abilities of charcoals to adsorb odors from wounds [7, 9]. This author published results regarding the adsorption of a range of organic vapors and also studied systematically the adsorption in various aqueous solutions, namely in the decolorization of contaminated tartaric acid solutions. The discussion of the contribution of charcoals to control odors from gangrenous ulcers was made by Kehl, in 1793, who also discovered that charcoal from animal origin (animal tissues) could be used to remove color from solution, including from sugar solutions [7, 9]. The introduction of carbon materials in industrial processes took place in England, in 1794, when wood charcoals were applied as bleaching agents in the processing of sugar. By that time, the method for preparing the wood charcoals was kept a secret [9]. In 1805, the first large-scale sugar refining facility was introduced in France by Gruillon, working with ground and washed wood char [9]. Between 1805 and 1808, Delessert demonstrated the effectiveness

named as nanoporous carbons.

38 Porosity - Process, Technologies and Applications

The first large-scale application in gas phase took place in 1854 [8], with the installation of carbon filters in London sewage ventilation systems. In 1872, carbon filters were also used in the masks of the chemical industry workers for preventing the inhalation of mercury vapors.

Besides thousands of years of history, and the already large range of applications for charcoals, it was only in the beginning of the twentieth century that one of the most outstanding abilities of carbon materials was explored: the possibility of enclosing a huge porosity into the carbon material structure. This "revolution" was due to the discoveries of Raphael von Ostrejko that, between 1900 and 1903, patented two different methods for the industrial activation of charcoal and the production of activated carbon materials [10]. This set of patents mentions the bases of the chemical activation process (carbonization of lignocellulosic materials with metallic chlorides) and of the thermal or physical activation (slight gasification of chars with water vapor or carbon dioxide at elevated temperatures) and also the specific equipment for thereof. The factory for full-scale activated carbon production was built by that time in Ratibor, now named Raciborz (Poland), and still operates, being so the world's oldest industrial activated carbon manufacturing plant [10, 11].

Although sugar industry was the first to apply activated carbons, in this case for whitening purposes, the starting point for the great development in the production and application of activated carbons was undoubtedly World War I, when these materials were used in gas masks [7, 8]. The production and search for new activated carbons has been boosted decade after decade due to their fundamental role in various technological applications which are related to, namely, restricted environmental regulations, recovery of valuable chemical compounds, and catalysts support [8, 12–14].

Nowadays, the driving forces for the research in nanoporous carbons are related with the properties of the most recent carbon materials: fullerenes [15], carbon nanotubes [16] and graphene [17]. However, the excellent properties of these novel carbon forms also fostered the interest in the traditional porous carbons and, in the recent years, a considerable number of studies searching for new synthetic approaches have been published. The main objective is the preparation of highly porous materials with controlled porosity, and often also with tuned surface chemistry, to present enhanced behavior as, for example, electrode materials for supercapacitors.
