Development and validation of a dynamic model for regeneration of passivating baths using membrane contactors

Zinc Chloride and Hydrochloric Acid Coextraction from Galvanizing Pickling Waste in the Presence of Iron(II). Results with Hollow Fiber Membrane Contactors

“…They have a very high surface area-to-volume ratio, leading to a reduced footprint. A number of studies have been conducted on the use of these HFM contactors; with respect to zinc extraction from spent pickling liquor, published works include both experimental and modeling results. − We have also previously demonstrated successful selective zinc recovery using membrane-based solvent extraction at a bench scale level . However, these studies focused only on zinc extraction even though tri- n -butyl phosphate (TBP) is known to also extract hydrochloric acid (HCl). − Earlier studies have shown HCl coextraction is small at such conditions, , and our intent is not to recover this acid as a valuable byproduct.…”

“…A useful summary of the mathematical modeling of HFM contactors is provided in Bringas et al In terms of the extraction of zinc from chloride solutions, the HFM modeling work by Torz et al, , Samaniego et al, and Polyga et al relied on mass transfer coefficients fitted to experimental data. On the other hand, Bringas et al derived their model from first principles, and hence no fitted parameters were required other than equilibrium constants. However, the computational approach involved solving of simultaneous partial differential equations and did not account for the baffled geometry and flow in the commercial HFM that was used.…”

Environmental Sustainability Assessment of an Innovative Cr (III) Passivation Process

“…7 The fact that the target components are extracted while others remain in the solution is based on the selection of the operational variables (pH) and the extractant. 4 Added advantages are its flexible and compact design.…”

“…The in situ removal of Zn (II) and Fe (III) impurities from the Cr (III) bath during the passivation is essential in order to avoid the loss of efficiency, reduce waste, and promote the resource efficiency of the process. Emulsion pertraction technology (EPT) enables the separation of Zn (II) and Fe (III) in acidic media while maintaining the concentration of Cr (III) constant. − EPT is a liquid–liquid extraction technology in which the extraction and back-extraction are conducted in a single membrane contactor. The membrane contactor consists of hollow fiber membranes that are microporous and hydrophobic, allowing the nondispersive contact between the passivation fluid and extractant phase.…”

“…The pores of the fiber are filled with the extractant because of the hydrophobic character of the membrane material . The fact that the target components are extracted while others remain in the solution is based on the selection of the operational variables (pH) and the extractant . Added advantages are its flexible and compact design.…”