Abstract: A multi-layer member of corrugated board made of active carbon fibers having an equilibrium adsorption amount of benzene of not less than 200 mg/g and a benzene adsorption rate constant of not less than 0.2 min.sup.-1.

Abstract: An adsorptive filter material having deodorizing, degassing and decolorizing properties which comprises an adsorptive sheet layer of active carbon fibers of which the active carbon fiber content is not less than about 20% by weight and reinforcing sheet layers of fibers having a single yarn strength of not less than about 2 g/denier and an elongation of not less than about 2% provided on the surfaces of the adsorptive sheet layer, the adsorptive sheet layer and the reinforcing sheet layers each weighing from about 20 to 2,000 g/m.sup.2.

Abstract: A process for preparing active carbon fibers which comprises (a) providing a cellulose fiber with a phosphorus compound reactive thereto, (b) subjecting the resulting fiber to heat treatment at about 200.degree. to 350.degree.C until the decreased percentage of fiber becomes about 40 to 75 % (W/W) and then (c) subjecting the resultant fiber to activation treatment at about 450.degree. to 1000.degree.C in an atmosphere containing not less than about 5 % (V/V) of steam until the decreased percentage of fiber becomes about 65 to 95 % (W/W), the said phosphorus compound showing a residual percentage of phosphorus of not less than about 70 % (W/W) after the heat treatment of the step (b) and a residual percentage of phosphorus of not more than about 10 % (W/W) after the activation treatment of the step (c).