Abstract:
The adsorption and desorption hysteresis of
110Ag
m on marine sediment interfaces under various particle concentrations, initial concentrations and adsorption kinetics were studied using traditional batch experiments. The results show that the adsorption and desorption process of
110Ag
m on marine sediments can be well described by the Freundlich isothermal model. The adsorption rate of
110Ag
m increases exponentially in 0.24 h, with a high adsorption rate immediately, and then gradually tends to be gentle. There is particle concentration effect phenomenon. Because with the increase of particle concentration, the isotherms tend to decrease. Desorption hysteresis is described by hysteresis angle (
θ) and thermodynamic index (TII). With the particle concentrations increasing from 0.1 g/L to 3.0 g/L, the values of TII and
θ first increase and then decrease. The adsorption expresses less reversible because as the adsorption of
110Ag
m to adsorption-sites of different combinations and particles could integrate after collision, this would decrease the specific adsorption surface area and sites. With the initial
110Ag
m concentration increasing, the value of TII first decreases and then increases, and the desorption hysteresis of
110Ag
m first decreases and then increases. There are two main reasons. Firstly, these phenomena are possibly caused by different microscopic structures of
110Ag
m on the marine sediment. Secondly, it is due to the diffusion restriction of narrow pore throat induced by the imbedded
110Ag
m molecules during high –concentration gradient force.Thus the adsorption system shows a certain degree of desorption hysteresis.