| In this study,a novel method of foam separation has been proposed to dispose chromium(Ⅵ) and manganese(Ⅶ) in water.In the experiment of chromium(Ⅵ) separation,systematic study was done respectively by intermittent and continuous experimental equipments.At the intermittent study,the effects of liquid feed concentration,pH value,air flow rate,and surfactant concentration on the removal efficiency of chromium(Ⅵ) were conducted by orthogonal experiment.And at the continuous experiment,operating parameters such as circumfluence ratio,liquid feed rate and liquid phase height were researched based on the former study.In the research of manganese(Ⅶ),the effects of liquid feed concentration,surfactant concentration,pH value and ionic strength on the removal efficiency of manganese(Ⅶ) were mainly conducted by intermittental experiment.The experiment for the removal of chromium(Ⅵ) from aqueous solutions had been done by foam fractionation intermittently.When the liquid feed concentration was 10 mg/L,the optimal operating parameters gained by analyzing the orthogonal experimental results were:the pH value of feed solution was 4.0, air flow rated 0.9L/min,and surfactant dosage was 300 mg/L.And the maximum removal efficiency of chromium(Ⅵ) reached 97.80%,which can be discharged directly.The kinetic test indicated that the foam separation of chromium was a first order process.The equivalent rate constant calculated from the slope was 0.4064h-1,and the equivalent rate equation wasν=0.4064C.Removal of chromium(Ⅵ) dissolved in water by continuous foam separation was conducted.The experimental results show that when the pH value of feed solution was 4.00,air flow rated 0.9m3/h,circumfluence flux was 15L/h, liquid feed rated 1L/h,surfactant concentration was 300 mg/L,liquid phase height was 105cm,the maximum removal efficiency of chromium(Ⅵ) reached 88.5%.It indicated that foam separation can remove chromium(Ⅵ) from aqueous solution steadily,but the size of setup and air bubble may influence it.Removal of manganese(Ⅶ) dissolved in water by intermittent foam separation was conducted.The experimental results show that the optimal operating parameters were:pH was nearly 4.0;air velocity was 1.0L/min.The best surfactant concentration(C2) was determined by the manganese(Ⅶ) concentration of liquid raw materials(C1),which can be calculated by beeline equation C2=7.4811C1-3.3019,and the correlation coefficient R2=0.9964.With the increase of the concentration of NO3-,the removal efficiency of manganese (Ⅶ) decreased,but the best surfactant concentration added. |
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