Study On Vertical Migration And Desorption Of Chemically Dispersed Oil On Beach

Spraying dispersants to control the oil spill pollution is one of commonlyemergency measures. The dispersants disperse oil components into small droplets andspread into water, which could accelerate decomposition rate of the oil spill fromseawater, but cannot completely make them disappeared. The formation of chemicallydispersed oil drifts to coastal drift, which migrates and releases into sand inside on theeffect of precipitation and seawater, may make the whole coast line polluted.Meanwhile，chemically dispersed oil contaminants release chronically and slowlypetroleum hydrocarbons, which pose a great threat to the offshore waters.Therefore,studying deeply the process of adsorption, migration and desorption of dispersed oilpolluted contaminants in sands will have important significance to furthermanagement and remediation of sands oil pollution.Firstly, study static adsorption and desorption of chemically dispersed oilcontaminants on gravels and main factors by erlenmeyer flask batch experiments;then, study the dynamic process of vertical migration and desorption of chemicallydispersed oil contaminants in sands by sand column. The following conclusions:(1) The adsorption of chemically dispersed oil contaminants on gravels conformto secondary dynamic model of Lagergren. The adsorption isotherm belongs toHenry’s equation. The equilibrium adsorption capacity increases with the increase ofsalinity, and with the decrease of pH and temperature.(2) Chemically dispersed oil polluted gravels in the seawater to release oilconform to secondary dynamic model of Lagergren. The high temperature and alkalipH is benefit for chemically dispersed oil polluted gravels in the seawater to releaseoil,but equilibrium desorption capacity has little change with the increase of salinity.(3) Adding the dispersant can promote migration ability of oil in the sand column,but the adsorption capacity decreases. Majority of oil contaminants are mainly trappedin the30cm upper layer by gravels. The retention rate is above93%. Theconcentration of chemically dispersed oil and particle sizes of gravels has an important influence on migration ability of oil in the sand column. The concentrationof chemically dispersed oil is higher, its migration depth is deeper. Migrationsituation of different particle sizes of gravels in the sand column are basically thesame, but the oil concentration of gravels is big different at the same depth. in theshallow layer gravel: the oil concentration of a（0.56~1.00mm）<the oil concentrationof b（0.25~0.56mm）<the oil concentration of c（0.15~0.25mm）; and in the lowerlayer gravel: the oil concentration of a（0.56~1.00mm）> the oil concentration of b（0.25~0.56mm）> the oil concentration of c（0.15~0.25mm）.(4)The initially quick process and the subsequently slow process occurs duringoil polluted gravels released in the column，the release rate of chemically dispersed oilpolluted gravels (34.40%) is higher than which of oil polluted gravels(8.90%). Thissuggests that the dispersant can promote the release of oil. Height of water and oilcontent of sand has an important influence on the release of oil in the sand column.The increase of height of water and oil content of sand can promote the release of oil.