Study Of Recovery Of Chromium From Electroplating Wastewater By Solvent Extraction

The process condition of treating electroplating wastewater containing high chromium by solvent extraction has been studied. Thermodynamics and kinetics of extraction process were discussed through single factor method.Tributylphosphate has been chosen as extractant and kerosene as diluents through consulting a large amount of documents and a certain experiments. High concentration of chromium as a model contaminant for wastewater treatment by solvent extraction has been investigated through single factor method. Various influence factors such as extraction temperature, aqueous equilibrium acidity, original concentration of extractant and the original concentration of Cr(VI) on equilibria of extraction were discussed. The results indicated that the distribution ratio was not influenced obviously by extraction temperature and diluents; but aqueous acidity, original concentration of extractant and original concentration of Cr(VI) effect greatly to the distribution ratio; The thermodynamic function value ΔH of the process was measured as 17.99kJ/mol. The solvent extraction mechanism to Cr(VI) by TBP in hydrochloric acid was discussed. The effect of extraction influenced by Various kinds of factors was discussed with orthogonal method such as temperature,the original liquid diluting the multiple, Organics volume/Water volume and concentration of TBP .The optimum process conditions were determined as follows: normal temperature,diluting the multiple 1.5 ,organics volume/Water volume1, concentration of TBP60%.Mass transfer kinetics of extracting chromium(VI) from hydrochloric acid media by TBP has been studied by the method of stationary interface stirring cell. The mass-transfer rate equation of the process is established as: The optimum process conditions of back extraction were determined as follows: stripping agent 5%NaOH,normal temperature, organics volume/Water volume 1.