Adsorption Kinetics, Equilibrium and Thermodynamics of Naphthalene onto Loess Soil

Adsorption behavior of naphthalene onto loess soil was investigated based on adsorption kinetic and adsorption isothermal experiments. The saturated adsorption capacity of naphthalene onto soil from Lanzhou (LZ) was higher than those onto loess soil from Jiayuguan (JYG). The soil properties have an obvious influence on adsorption of naphthalene on loess soil. The naphthalene adsorption equilibrium was reached within 24h, and the adsorption kinetics was well described by the pseudo-second-order model, and also followed the intraparticle diffusion model. The adsorption processes were controlled by the external liquid film diffusion, surface adsorption, intra-particle diffusion, etc. Besides, the adsorption equilibrium data were fitted well with the Henry and Freundlich isothermal model. The saturated adsorption capacity was weakened with the decrease of temperature, suggesting a spontaneous endothermic process. The results of thermodynamic parameters analysis showed the adsorption was mainly a physical process and was enhanced by chemical adsorption.