The present invention relates to a carbonaceous material having a silicon element content of less than 200 ppm, a powder conductivity of 10.0 to 22.0 S/cm, a total amount of surface functional groups of 0.22 to 0.36 meq/g, and a pore volume of 0.10 to 0.20 cm.sup.3/g in terms of pores having a pore size of not less than 4 nm as measured by a BJH method.

A solidified porous carbon material uses a plant-derived material as a raw material, a bulk density of the solidified porous carbon material is in the range of 0.2 to 0.4 grams/cm.sup.3, preferably, 0.3 to 0.4 grams/cm.sup.3. A value of a cumulative pore volume in the range of 0.05 to 5 μm in pore size based on a mercury press-in method is in the range of 0.4 to 1.2 cm.sup.3, preferably, 0.5 to 1.0 cm.sup.3 per 1 gram of the solidified porous carbon material.

A solidified porous carbon material uses a plant-derived material as a raw material, a bulk density of the solidified porous carbon material is in the range of 0.2 to 0.4 grams/cm.sup.3, preferably, 0.3 to 0.4 grams/cm.sup.3. A value of a cumulative pore volume in the range of 0.05 to 5 μm in pore size based on a mercury press-in method is in the range of 0.4 to 1.2 cm.sup.3, preferably, 0.5 to 1.0 cm.sup.3 per 1 gram of the solidified porous carbon material.

Smoking article include a smokable material and an activated carbon particle downstream of the smokable material. The activated carbon particle is produced from a whole seed. The activated carbon particle has a length, width and height. At least two of the length width and height are independently in a range from about 1 mm to about 7.5 mm. The particles can be spheroids, in which case the length, width and height would be the same or similar.

Smoking article include a smokable material and an activated carbon particle downstream of the smokable material. The activated carbon particle is produced from a whole seed. The activated carbon particle has a length, width and height. At least two of the length width and height are independently in a range from about 1 mm to about 7.5 mm. The particles can be spheroids, in which case the length, width and height would be the same or similar.

Composite carbon particles including a porous carbon material and a silicon component, the composite carbon particle having an average aspect ratio of 1.25 or less, and a ratio (I.sub.Si/I.sub.G) of a peak intensity (I.sub.Si) in the vicinity of 470 cm.sup.−1 to a peak intensity (I.sub.G) in the vicinity of 1580 cm.sup.−1 as measured by Raman spectroscopy of 0.30 or less, wherein the porous carbon material satisfies V.sub.1/V.sub.0>0.80 and V.sub.2/V.sub.0<0.10, when a total pore volume at a maximum value of a relative pressure P/P.sub.0 is defined as V.sub.0 and P.sub.0 is a saturated vapor pressure, a cumulative pore volume at a relative pressure P/P.sub.0=0.1 is defined as V.sub.1, a cumulative pore volume at a relative pressure P/P.sub.0=10.sup.−7 is defined as V.sub.2 in a nitrogen adsorption test, and has a BET specific surface area of 800 m.sup.2/g or more.

Composite carbon particles including a porous carbon material and a silicon component, the composite carbon particle having an average aspect ratio of 1.25 or less, and a ratio (I.sub.Si/I.sub.G) of a peak intensity (I.sub.Si) in the vicinity of 470 cm.sup.−1 to a peak intensity (I.sub.G) in the vicinity of 1580 cm.sup.−1 as measured by Raman spectroscopy of 0.30 or less, wherein the porous carbon material satisfies V.sub.1/V.sub.0>0.80 and V.sub.2/V.sub.0<0.10, when a total pore volume at a maximum value of a relative pressure P/P.sub.0 is defined as V.sub.0 and P.sub.0 is a saturated vapor pressure, a cumulative pore volume at a relative pressure P/P.sub.0=0.1 is defined as V.sub.1, a cumulative pore volume at a relative pressure P/P.sub.0=10.sup.−7 is defined as V.sub.2 in a nitrogen adsorption test, and has a BET specific surface area of 800 m.sup.2/g or more.

The present invention relates to composite particles containing silicon and carbon, wherein a domain size region of vacancies of 2 nm or less is 44% by volume or more and 70% by volume or less when volume distribution information of domain sizes obtained by fitting a small-angle X-ray scattering spectrum of the composite particles with a spherical model in a carbon-vacancy binary system is accumulated in ascending order, and a true density calculated by dry density measurement by a constant volume expansion method using helium gas is 1.80 g/cm.sup.3 or more and 2.20 g/cm.sup.3 or less.

In a method of preparing an immobilized selenium system or body, a selenium — carbon — oxygen mixture is formed. The mixture is then heated to a temperature above the melting temperature of selenium and the heated mixture is then cooled to ambient or room temperature, thereby forming the immobilized selenium system or body.

In a method of preparing an immobilized selenium system or body, a selenium — carbon — oxygen mixture is formed. The mixture is then heated to a temperature above the melting temperature of selenium and the heated mixture is then cooled to ambient or room temperature, thereby forming the immobilized selenium system or body.