Application of Hollow Fiber Membrane Contactors for Catalyst Recovery in the WPO Process

Abstract

In this work the use of a membrane based liquid extraction process for recovery of the homogeneous catalyst employed in the wet peroxide oxidation process (WPO) is studied. In the WPO process the oxidation agent is the hydroxyl radical that is obtained by using a combination of hydrogen peroxide and a mixture of Fe(II), Cu(II), and Mn(II) in aqueous solution. The mixture of metallic cations permits the almost total degradation of the refractory organic compounds, but the use of metallic salts as catalysts induces additional pollution. To recover the homogeneous catalyst of the WPO process by means of non-dispersive solvent extraction (NDSX) two hollow fiber membrane contactors are employed, one for the extraction step and the second for the back-extraction step. From the initial assays, the extractant LIX 622N was selected for Cu(II) recovery and Cyanex 272 for Fe(II) and Mn(II) recovery. Selective separation of Fe(II) and Mn(II) can be obtained by adjusting the pH of the feed aqueous phase. The three metals are stripped using sulfuric acid to give concentrated solutions of CuSO(4), FeSO(4), and MnSO(4) that can be recycled to the formulation of the catalyst solution of the WPO process. A mathematical model has been proposed to describe the recovery of Cu. Two design parameters are required: the membrane mass transport coefficient of the extraction and stripping modules (k(m) = 3.07 x 10(-7) m/sec) and the equilibrium parameter of the extraction reaction (K(Ex) = 0.0832).

A mathematical model for release of biologics from porous hollow fibers

“…Hollow fiber membranes have experienced widespread use in industries such as food, juice, pharmaceutical, metal working, dairy, wine and (most recently) municipal drinking water. [1][2][3][4][5][6][7][8][9][10][11] Depending on the application, processes based on hollow fiber membranes can be highly practical and cost effective alternatives to conventional chemical and physical separation processes due to their high surface area to volume ratio and the ability to allow molecules to pass through the membrane in a selective and controllable manner. In the separation technology field, large volumes can be filtered through the fibers, while utilizing minimal space and low power consumption.…”