Characteristics and applications of the Lagergren's first-order equation for adsorption kinetics

Adsorption kinetic curves of the Lagergren's first-order (LFO) equation were classified into four zones according to their rising characteristics. Of the 85 adsorption systems described by LFO equation, 46% of the kinetic curves belonged to zone II and 29% to zone III, these being good and fast. Activated carbons with a BET surface area of 626–1009 m2/g and a micropore volume fraction of 57.5–88.0% were prepared from plum kernels, pinewood, pistachio shells, and Moso bamboo with steam activation. The adsorption kinetics of methylene blue, tannic acid, humic acid, and phenol on these activated carbons were studied. Normalized standard deviations were shown that the adsorption of methylene blue, tannic acid, and humic acid was better described by LFO equation and that of phenol by PSO equation. Also, the value of k1tref was obviously affected by physical properties and particle sizes of the adsorbents as well as molecular weights of the adsorbates.