ADSORPTION CHARACTERISTICS OF CARBONIZED BARK FOR PHENOL AND PENTACHLOROPHENOL

The potential of using carbonized slash pine bark as a substitute for activated carbon was examined in this study. The bark was carbonized b y slow heating in nitrogen for 6.5 h to 672 degrees C. The BET-N-2 sur face area, average micropore and mesopore diameter, and micropore volu me were 332 m(2) g(-1) 21.7 Angstrom, and 0.125 cm(3) g(-1), respectiv ely. The adsorption capacities for phenol and pentachlorophenol (PCP) at pH 2 and pH 8 were evaluated. The Langmuir equation provided a slig htly better fit than the Freundlich equation to two sets of phenol dat a. The calculated Freundlich constants, K = 0.41 - 0.58 mmol/g/(mmol d m(-3))(1/n) and 1/n = 0.30 - 0.41, were lower and higher, respectively , than literature values for activated carbons. The adsorption capacit y of the carbonized bark was much lower for PCP than for phenol. The p rotonated and anionic PCP isotherms were Type II or III, respectively, in the Brunauer classification. The BET equation provided the best fi t to protonated PCP isotherm data. The anionic PCP data were fitted to both the BET model and an equation used in the literature to represen t phosphate adsorption on activated carbons. Nonlinear regression of t he data for both phenol and PCP adsorption with the Freundlich, Langmu ir and BET equations generally gave more accurate parameters, compared with the use of linearized equations to obtain the parameters. (C) 19 98 SCI.