| With modern production and rapid development of science and technology, we have put forward new demand in separating the trace components. On one hand, a lot of valuable materials often exist with very low density, in order to draw these materials, we must solve the separation problem of the trace components in the rare solution. On the other hand, we have put forward very harsh demand for the product quality and purity. For example, in the industries of atomic energy and semiconductor, the purity of argon, helium, silicon, and germanium is 99.99 %, some of them even exceeds 99. 9999%. In terms of environmental protection, we require that the density of such harmful substance as the heavy metal ion and the organic matter, etc. in the water of industry is lower than 0.5mg/L. The separation of trace components is also challenged from the purifying industry. So the traditional separation method seems powerless to the separation of the trace components in the dilute solution.Foam fractionation is known to have potential for separation and concentration of the material of surface activation with the medium of bubbles. It has many property, such as simple craft, low cost, small area of occupation of land, meeting the changes of the quality and flow of the water and recovering many valuable components at same time. Foam fractionation has very good development prospect because of its good effect of separation when it separate of trace components with a rank of ppm.In this dissertation, fractionation of SDBS(sodium dodecyl benzene sulfonate), Ni~2+, Pb~2+ and Cr(VI) in the waste water and the operation parameters are studied. The experimental results show that the effect of separation are influenced by the density of bubbles, pH, the concentration of SDBS and coagulate, the gas-liquid ratio and the operation of circumfluence.The experimental results show that the best condition of fractionations of SDBS is that the gas-liquid ratio is 5 to 1; the best condition of fractionation of Ni~2+is that the gas-liquid ratio is 4 to 1, pH is 9 and the concentration of SDBS is . 15mg/L; the best condition of fractionation of Pb~2+is that the gas-liquid ratio is 3 to 1, pH is 10, the concentration of SDBS is 20mg/L, and the concentration of Al2(SO4)3 is 3 to 1 (the mole ratio of Al3+ to Ni2+); and the best condition of fractionation of Cr(VI)is that the gas-liquid ratio is 3 to 1, pH is 10, the concentration of SDBS is 10mg/L, and the concentrations of FeSO4 is 5 to 1 (themole ratio of Fe2+ to Cr(VI)).Under the best condition, when the density of SDBS, Ni2 + , Pb2+ and Cr(VI)is 30mg/L, 10mg/L , 10mg/L and 10mg/L respectively in the raw materials liquid, the isolation rate of the four components is 91.2%, 96.2%, 97.1% and 97.3%, respectively, and the concentrations of the separated materials in the waste water are lower than that of the standard of discharge of the national sewage.According to the similar of foam fractionation process and chemical reaction process in physical behavior, we applie the theory of chemical reaction progress to the foam fractionation, and then introduce the equivalent chemical reaction constant. The macroscopical dynamics is studied by adopting law of coprecipitiation flotation to get rid of the Cr(VI) in the waste water. The result indicates that under one balance state the process of coprecipitation flotation can be regarded as one grade reaction under the best isolation rate, which equivalent speed constant is k = 0.537 . Through measuring arid analyzing the distribution of resting time, we get its average resting time tm = 9.85min , variance = 0.525 .Combined the relevant experiment, the distribution density functionof resting time is confirmed. The influence factors about the foam fractionation process isolation rate of fluid flowing are studied.
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