Mass Transfer and Extraction of Zinc from Rinse Water of Zinc Phosphate Coating via A Hollow Fiber Supported Liquid Membrane

The extraction of Zn(II) ions from phosphating rinsing waters in automotive assembly process was investigated though a hollow fiber supported liquid membrane (HFSLM) by using di(2-ethyhylhexyl) phosphoric acid (D2EHPA)as a highly selective carrier for the transfer of zinc ions which diluted in kerosene and sulfuric acid solution have been used as the stripping solution. The various chemical parameters, such as the pH of the initial feed solution, the concentration of carrier, the concentration of stripping solution, the flow rate of feed and stripping solution were investigated. The optimum condition have been determined. The extraction of Zn(II) from feed phase was achieved at 91% by 8%(v/v) or 0.25 molar of D2EHPA. Mass transfer modeling in the system was developed to predict the extent of Zn(II) extraction at different time. Extraction equilibrium constant (Kex), distribution ratio (D), permeability (P) and mass transfer were determined. The aqueous-phase mass-transfer coefficient (Ki) and organic-phase mass-transfer coefficient (Km) were calculated.