title: Kinetic studies on the adsorption of phenol, 4-chlorophenol, and 2,4-dichlorophenol from water using activated carbons.
abstract: This study uses rate parameters in pseudo-first-order (PFO) and pseudo-second-order (PSO) equations (k(1) and k(2)q(e), respectively) to judge the extent for approaching equilibrium in an adsorption process. Out of fifty-six systems collected from the literature, the adsorption processes with a k(2)q(e) value between 0.1 and 0.8 min(-1) account for as much as 70% of the total. These are classified as fast processes. This work compares the validity of PFO and PSO equations for the adsorption of phenol, 4-chlorophenol (4-CP), and 2,4-dichlorophenol (2,4-DCP) on activated carbons prepared from pistachio shells at different NaOH/char ratios. The activated carbons, recognized as microporous materials, had a surface area ranging from 939 to 1936 m(2)/g. Findings show that the adsorption of phenol, 4-CP, and 2,4-DCP on activated carbons had a k(2)q(e) value of 0.15-0.58 min(-1), reflecting the fast process. Evaluating the operating time by rate parameters revealed that k(2)q(e) was 1.6-1.8 times larger than k(1). These findings demonstrate the significance of using an appropriate kinetic equation for adsorption process design.
authors.affiliation: Department of Safety, Health and Environmental Engineering, National United University, 1 Lien Da, Kung-Ching Li, Miao-Li 360, Taiwan.
authors.forename: Ru-Ling
authors.initials: RL
authors.lastname: Tseng
authors.forename: Keng-Tung
authors.initials: KT
authors.lastname: Wu
authors.forename: Feng-Chin
authors.initials: FC
authors.lastname: Wu
authors.forename: Ruey-Shin
authors.initials: RS
authors.lastname: Juang
mesh_terms: D001673:Biodegradation, Environmental; D002606:Charcoal / Q000737:chemistry*; D002733:Chlorophenols / Q000493:pharmacokinetics*; D010636:Phenols / Q000493:pharmacokinetics*; D027927:Pistacia; D012972:Sodium Hydroxide; D013499:Surface Properties; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
chemical_list: D002733:Chlorophenols; D010636:Phenols; D014874:Water Pollutants, Chemical; D002606:Charcoal; D012972:Sodium Hydroxide