| Daqing oilfield has entered high water cut development late now,on a large scale using oil recovery of polymer flooding and asp flooding,so polyacrylamide(PAM)as oil displacement in polymer is a wide range of applications in the field.Polyacrylamide can enhance the recovery efficiency of oilfield to some extent,but its production,transportation,oil production in the event of leaking into the soil,will lead to soil harden and even more serious environmental pollution problems.Soil is the most basic human production,life and also the most important resources,and daqing-a city born because of oil,the earth is full of petrochemical enterprises,PAM large-scale use of local soil caused serious pollution.The soil type of daqing is dominated by chernozem.Therefore,the study of the adsorption law of polyacrylamide in chernozem has important guiding significance for the restoration and protection of soil ecological environment.Experiments in a certain area of daqing oil field production plant is the production line measurement results show that PAM content in soil around station configuration,asp flooding around the injection well PAM content in soil is less,high failure of surrounding content,production is the main link of polymer leak.After discussion,the pollution standard of PAM was set as 1000 mg/L,and the amount of PAM in the soil surrounding the polymer injection well and the well was seriously exceeded,so it was very important to study the adsorption behavior of PAM in soil.Then in the laboratory average molecular weight of 5 million was studied by static adsorption characteristics of polyacrylamide in daqing chernozem soil adsorption kinetics and thermodynamics of the adsorption of polyacrylamide in chernozem rule has carried on the system research,and examines the oil extraction wastewater contains oil and alkali and surfactant on the absorption of polyacrylamide.According to the variation of concentration with time,the type,kinetics equation,isothermal adsorption curve,isothermal adsorption equation and adsorption equilibrium constant of static adsorption are fitted.This study also examines the temperature on the adsorption and the effect of polyacrylamide in each experimental temperature isothermal adsorption curve fitting,get each temperature adsorption equilibrium constant,then the thermodynamic parameters were calculated.The experimental results show that the adsorption process of polyacrylamide in chernozem fits a pattern of typical Langmuir type adsorption,adsorption process is very quick,two hours before the stage of PAM adsorption quantity can reach about 90% of the saturated adsorption amount,adsorption rate is gradually slow down after,eventually saturated adsorption in 4-5 hours.The adsorption process of PAM in the soil adsorption capacity increased with the increase of equilibrium concentration increased,and a significant increase in low balance concentration range,then the equilibrium concentration increased,soil adsorption quantity increase of decrease of polyacrylamide,eventually flatten out,infinite close to a constant value.Dynamic experimental results show that with the adsorption of PAM on chernozem in accordance with first order kinetics model,namely the adsorption rate and adsorption mass concentration of a direct ratio,the linear correlation coefficient reaches 0.9 above.The adsorption equilibrium constants of Langmuir isothermal adsorption at different temperatures were obtained,and the thermodynamic parameters were calculated according to the temperature and the adsorption equilibrium constants at the corresponding temperature.?H=29.28KJ/mol,indicating that the adsorption process absorbs heat and absorbs heat;It is shown that the adsorption of polyacrylamide in soil is spontaneous.The entropy change of ?S >0 indicates that the adsorption reaction of polyacrylamide on soil samples will increase the disorder of the system and increase the entropy value.Experiment investigates the asp flooding produced water in the oil,alkalinity and surfactants on the absorption of polyacrylamide in chernozem,the experimental results show that because of the oil with PAM adsorption in the soil of compete,the presence of certain amount of oil will reduce PAM adsorption in the soil,oil content increases to a certain value,PAM adsorption quantity not to reduce.The experiment showed that the adsorption of polyacrylamide in the soil under neutral conditions was the most,and the partial acidity or alkalinity would decrease the adsorption capacity.The presence of surfactants has no effect on the adsorption of polyacrylamide. |
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