| Organic pollution matters such as phenols and PAHs in soil is aggravating, which is due to the use of chemical fertilizers, sewage irrigation, solid waste land and so on. The ability of soil retaining organic pollutants is in a very limited range, organic pollutants will transport downward into groundwater and cause water pollution. Therefore, it is essential to establish the technical means, which is on the premise of not impede the soil water infiltration, set up the blockages of adsorption pollutants in the soil, aimming at preventing and controlling pollutants migrating down.In saturated soil column transport experiments, non reactive ion Cl- was used to explore the soil column parameters, and these column parameters were used to calculate the transport parameters of the reactive solute phenol. It aims to explore retarding effect of the cetyltrimethylammonium bromide(CTMAB) modification and raw soil on phenol by migration parameters of phenol, and the effect of modification ratio, the thickness of the soil, height of water and environment such as pH, ionic strength and the concentration of phenol on migration in soil column, then through simulation test to simulate the migration of phenol in soil column, the following conclusions:(1) The greater the modification ratio was, the later the flow time of Cl- and phenol was, and the greater the retardation coefficient Rc was. With the modified ratio increasing from 0 to 100%, both the retardation coefficient Rc and average penetration time T0.5 follow the order: 100%CT>50%CT> 25%CT > 10%CT >> CK. In addition, both the retardation coefficient Rd and unit holding amount of phenol in soil increases with the increase of modified ratio in elution process. With the increase of soil thickness, the block ability of soil samples to Cl- was weaken, while the block ability of soil samples to phenol was enhancement. With the increase of height of water, the block ability of raw soil to phenol was weakened, however the block ability of 100% and 50% modified soil to phenol had no obvious change.(2) With the pH increasing from 4.0 to 10.0, the block ability of soil samples to Clwas decreasing, effects of modified soils to block phenol migration had almost no transformation, except the block ability of 100% modified soil to phenol in pH 4.0 is larger. In addition, both the retardation coefficient Rd and unit holding amount of phenol in soil had no obvious change with the increase of pH in elution process.With the ionic strength increasing from 0.001 to 0.1 mol/L, the flow time of phenol in raw soil was advanced from 4.07 pv to 3.42 pv, and the retardation coefficient Rc dropped from 0.56 to 0.37. The flow time of phenol in 100% modified soil was advanced from 130.47 pv to 55.27 pv, the retardation coefficient Rc dropped from 17.57 to 8.71, and the amount of unit holding of raw soil and 100% modified soil were reduced. With the increase of pollutants concentration, the block ability of low proportion modified soil were no obvious change, but the block ability of high proportion modified soil is enhance. The unit holding amount to phenol of soil samples were increased with the increase of phenol concentration.(3) It is confirmed that the block ability to organic pollutants of subsurface soil modified by CTMAB was enhanced through simulation test, subsurface soil after modification can significantly slow the speed of organic pollutants infiltration with soil water. When phenol concentration is 100 mg/L, the raw soil can be penetrated is about 72 days, if subsurface farmland soil is modified with 100% of CEC in 5 cm deep, penetrating time needs about 1204 days, even subsurface farmland soil is modified with 50% of CEC in 5 cm deep also need to about 706 days, it can won the time for effective engineering repair measures, and provide an arena for microbial decomposition of organic matter. |
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