Research On Seepage And Storage Characteristics Of Modified Bentonite And Adsorption Of Pollutants

Bentonite is good at dealing with soil heavy metal ions as adsorption firming agent because of its strong adsorption properties,but the natural bentonite in water is easy to expand,due to its extremely low permeability,it is difficult to save water but also it is difficult for heavy metal ions to enter into bentonite to adsorb.In order to solve this problem,the bentonite composite material with the properties of non-expansion in water,good permeability and adsorption is obtained by using natural bentonite mixed with plant ash,fly ash,cinder,activated carbon and cement respectively and roasting at high temperature.This paper study the infiltration and storage characteristics of modified bentonite and the adsorption law of pollutants by combining experimental,theory and simulation methods.The research work and the main conclusions are as follows:The permeability of modified bentonite is at least 10⁵ times higher than natural bentonite when the seepage fluid is distilled water.When the seepage fluid is polluted water containing heavy metal ions,the pore channels are blocked by heavy metal ions in the water due to adsorption and precipitation,and the permeability decreases as a negative exponential function.When the adsorption reaches saturation equilibrium,the permeability reaches a stable state.The results show that both the water absorption curve and the dehydration curve of modified bentonite meet the bilinear variation law.In the early stage of the water absorption curve,the water absorption rate is fast,and the water content in the later stage increase steadily.In the dehydration curve,the dehydration speed of the specimen is slow,and the water holding capacity is strong.In the later stage of dehydration,the residual water exists in the specimen in the form of water film,and the modified bentonite has a good water storage capacity.Experiment of modified bentonite adsorption,the control variable method is used to study,the influence on the types of modified bentonite composite materials,the initial concentration of heavy metal ion,heavy metal ion species on law of adsorption effects are obtained respectively and adsorption curve is smooth acceleration-bilinear incremental change rule,in the adsorption of Cu²⁺,five kinds of modified bentonite composite ion removal rate of 99%or more,removal rate sorting:plant ash-bentonite>fly ash-bentonite>cinder-bentonite>activated carbon-bentonite>cement-bentonite.Based on the seepage and adsorption experiment of modified bentonite and seepage diffusion theory,the saturated and unsaturated seepage mechanics model of bentonite and the transport convection diffusion mechanics model of pollutant transport are established.According to simulate,the purification rule of heavy metal ions by bentonite is obtained.