Abstract: The kinetic and thermodynamics of juglone sorption onto yak hair as a model system were investigated.It was found that the sorption kinetics of juglone on hair followed a pseudo-second-order kinetic model.The equilibrium sorption capacity increased as the temperature increasing from 303 to 333 K.The maximum equilibrium sorption capacity was 18.957 mg/g at T = 333 K.By the combination of experiment and theory,Freundlich and Langmuir isothermal equation can fit adsorption data well.But the adsorption of juglone onto hairs was better described by the Freundlich isothermal equation.In addition,according to the adsorption thermodynamics parameters,the adsorption of juglone onto hairs was spontaneous,endothermic and increasing entropy process.The process of adsorption was mainly physical adsorption.During the isothermal equation,the negative ΔG suggested that the adsorption process was spontaneous,ΔH was greater than 0,indicating that the adsorption was exothermic.An activation energy of sorption had also been evaluated with the pseudo-second order rate constants,the E_a in this study was 30.09 kJ/mol,indicating that the adsorption was a typical physical adsorption.

Key words: juglone, adsorption kinetics, adsorption isotherm, Freundlich, thermodynamics, activation energy