Preparation of Active Carbon from Phenol-Formaldehyde Resin

Abstract

Phenol-formaldehyde resin was carbonized at 700°C and then activated with steam under fluidized conditions. The experimental conditions were as follows, activation temperature: 920°C; activation time: 2-5 hours; nitrogen flow rate: 5 //min; steam flow rate: 0.7 g-H₂0/ g-char, hr.
Specific surface area, pore size distribution, equilibrium adsorption isotherms and adsorption rate of methylene blue and sodium dodecylbenzene sulfonate (DBS) were measured for each active carbons.
More than 90% of pore volume consisted of pores smaller than 100Å in radius. Values of pore volume smaller than 100Å in radius were 0.379-0.978 ml/g.
The values of specific surface area of active carbon increased with decreasing weight and reached 2000 m²/g at about 75% weight loss. The reactivity of phenol-formaldehyde resin char with steam was lower than that of coal char.
Both equilibrium adsorption amount and effective pore diffusivity of methylene blue and DBS increased with activation. For the adsorption of methylene blue and DBS, the ratio of effective pore diffusivity to free diffusivity were of the order of 10-⁷-10-⁵ and 10-⁵-10-⁴, respectively.
Volume of pores smaller than 100Å in radius appeared to be very important for these adsorbates.
Active carbons whose specific surface area were more than 1500 m²/g showed higher adsorption properties than commercial ones.