[Adsorption kinetics of phenol on organic modified Lou soil]

Using batch experiment, the adsorption kinetics of phenol on both tillage layer (TL) and clay layer (CL) of Lou soil modified with cetyltrimethylammonium bromide (CTMAB, CB) at various ratio (100 CB and 50 CB) and cetyltrimethylammonium bromide + sodium dodecylsulphonate (CTMAB + SDS, CS) mixture were carried out, and its mechanism was discussed also. The results showed that two adsorption velocity parameters of phenol, total-adsorption-velocity (Vt) and fast-adsorption-velocity (Vf), on both layers of modified soil are 2.64-3.31 microg x (g x h)(-1), 39.19-61.23 microg (g x h)(-1) at low added phenol concentration respectively and 13.09-16.30 microg (g x h)(-1), 247.87-325.64 microg (g x h)(-1) at high added phenol concentration respectively at two experimental temperature, moreover, the two velocity parameters have a same sequence in different modification treatments, i.e., ordered by 100 CB > 120 CS > 50 CB > CK in TL treatment and by 100 CB > 50 CB > 120 CS> CK in CL treatment. These outcomes indicated that the modification on the both layers of Lou soil increases significantly the adsorption velocity of phenol. The adsorption of phenol is divided into two stages, fast adsorption and slow adsorption, in which the adsorption of phenol is primarily decided by the fast adsorption while it is affected little by slow adsorption. Therefore, the velocity parameters that relate with the fast adsorption have better correlation between them. The time of conversion (t(c)) between fast adsorption and slow adsorption in modified soil is less than 2 h, and shows a reverse sequence in different modification treatments compared to the adsorption velocity parameters. The adsorption velocity of modified CL to phenol is higher than that of modified TL. The adsorption velocity of organic modified soil to phenol can be increased by an increase of both temperature and added concentration of phenol. The exponential II kinetic model is the best model to describe the adsorption kinetic curves of phenol on modified soil, furthermore, the fitted parameter A has better correlation with the velocity parameters related to the fast adsorption while the fitted parameter--B, which can become a characteristic parameter to describe the adsorption velocity, has better correlation with the time of conversion to. The adsorption of phenol on the modified soil is primarily decided by the hydrophobic adsorption of organic phase on the surface of modified soil.