Study On The Transport And Interaction Of Vanadium And Soil Colloids In Saturated Porous Media

Vanadium pollution in soil has posed the serious long-term threat to the natural environment and human health gradually, the harm caused by high concentration of vanadium accumulating toxic and carcinogenic has also attracted people’s great attention, further study on the migration behavior of vanadium and its ecological effect to the environment do have significant meaning. The study on the migration of soil colloid has become a focus, also, mobile soil colloid plays a vital role on the behavior of pollutants in environment.The research on the interaction mechanism between vanadium、soil colloid and porous media will strengthen the understanding of the pollutant colloid-facilitated transport in porous media, providing the important scientific theoretical guidance to the vanadium pollution prevention in soil.This study selected two kinds of different structure colloid of kaolinite and montmorillonite and collected four kinds of typical soils in China(Loessal soil、Aeolian sandy soil 、 Lou soil and Yellow-cinnamon soils). Using laboratory experiments and mathematical model simulation to investigate the effects of flowrate、solution pH and ion strength on heavy metal and soil colloid transport in saturated porous media. On this basis, the study mainly focused on the migration mechanism of interaction between vanadium and soil colloid in saturated porous media. The results of the study are as follows:(1)The increase on the flowrate will reduce the vanadium deposition in sand column, promoting its transport; as the variation of pH from 4-8, the migration of vanadium will be improved correspondingly; using HYDRUS – ID model could mimic the transport of vanadium in saturated porous media, and fitting result achieves a prominent correlationship with measurement data.(2)Aeolian sandy soil colloid and Yellow-cinnamon soil colloid showed stronger transport ability under alkaline conditions, while high acidic condition will reduce, compared to them, Loessal soil and Lou soil colloid was more likely to deposit, and both of them showed stronger ability in neutral and alkaline conditions.In general, kaolinite and montmorillonite colloid had the strongest ability of migration in porous media within the change of the different solution pH.(3)Except the Lou soil colloid, the peak of other five colloids breakthrough curve reduced as the ionic strength increased. Compared with the montmorillonite, kaolinite colloid was easier to strand with the ionic strength of 0.01 mol/L、0.1 mol/L in porous medium, reducing its ability to migrate.(4)The co-transport between soil colloid and vanadium showed that correlation of vanadium and soil colloid in vanadium-contaminated column was higher than that vanadium-soil colloid complexus. This was mainly caused by the different adsorption and desorption process, including the facilitation of vanadium adsorption and retention of vanadium desorption.