The Adsorption And Blocking Effects Of Weihe Sediments On Polltants

Weihe is the mother of Shaanxi, the riverside water source of which provides a certain amount of living and production water to coastal cities. Weihe has been polluted seriously, but the quality of its riverside water is good, for there are a few pollutants in groundwater, or no pollution components. Maybe the reason is that the adsorption and blocking effects of Weihe sediments on polltants play an important role in the protection of groundwater. According to pollution situation of Weihe and taking into account the impact on human health, three types of pollutants Pb2+, anthracene, NO3- were selected to do adsorption experiment on Weihe typical sediments(clay, silt, fine sand, medium sand, coarse sand); the blocking coefficients of Weihe sediments on Pb2+, anthracene, NO3- were calculated and analyzed, and the effects of adsorption capacity, permeability, organic content, pH value on blocking effect were studied. The results obtained are as follows:1.The adsorption kinetics of Pb2+, anthracene on Weihe sediments are consistent with second-order kinetic equation; the adsorption rate order: coarse sand> medium sand> fine sand> silt> clay; the adsorption equilibrium time of Pb2+ and anthracene is about 2h,24h respectively.2.The results of isothermal adsorption research are as follows:â‘ The isothermal adsorption curves of Pb2+ on Weihe sediments are in line with Langmuir equation; the maximum adsorption capacity of Pb2+ on clay deposit is 21g/kg, and when the initial concentration is less than 50mg/L, the adsorption ratio is greater than 93%.â‘¡The isothermal adsorption curve of anthracene on clay layer deposit is in accordance with Henry equation, and the isothermal adsorption curves of anthracene on silt layer, fine sand layer, medium sand layer, coarse sand layer deposit conform Henry, Freundlich equation; when the initial concentration of anthracene is 0.08-2.5mg/L, the adsorption ratio of anthracene on clay sediment is between 98-99%.â‘¢It is not easy for NO3- to adsorp on Weihe sediments.3.The adsorption capacity of Pb2+ on sediments rises with the increasing of temperature and pH; the adsorption capacity of anthracene on sediments falls with the increasing of temperature,and the pH value has a weak effect on the adsorption of anthracene. 4.Known from the blocking coefficients of Pb2+,anthracene,NO3- in Weihe sediments,the blocking effect of Weihe different deposition layers on Pb2+ and anthracene is good, and the blocking ability of anthracene is greater than Pb2+,however,no blocking effect on NO3-.The paper provides a basis theoretical support for further studying of relations between polluted river and the quality of groundwater.