Selective extraction of zinc and iron from passivating baths

Zinc recovery and waste sludge minimization from chromium passivation baths

“…The chromium concentration decrease observed was mainly a dilution effect caused by the addition of sodium hydroxide solution to the feed tank, necessary for the maintenance of constant pH, otherwise, the pH would decrease due to the exchange reaction between metal cations and protons, as explained before. Nevertheless, the influence of pH onto chromium extraction was evaluated in a previous work [26], resulting that the loss of chromium mass at a pH of 2.5 was maintained below 3%. After 4 consecutive cycles, iron is almost completely removed from the feed phase reaching a final concentration in the range of 0.8-2.0 mg L −1 (97-99% iron removal).…”

Membrane Processes

“…Camarillo et al (2010) demonstrated the removal and recovery of copper (II)-loaded aqueous nitrate Water Environment Research, Volume 83, Number 10-Copyright © 2011 Water Environment Federation solutions by utilizing polymer enhanced UF (PEUF) andelectrodeposition. The study showed that PEUF was effective at metal retention with a 99.5% copper(II)retained.The authors also demonstrated that electrodeposition achieves higher recovery of copper without the drawbacks of chemical regeneration Mediavilla et al (2010). demonstrated that zinc and iron (undesired constituents) can be removed from passivating baths while maintaining the desired chromium concentrations by utilizing Emulsion Pertraction Technology (EPT), a liquid-liquid extraction process performed in membrane contactors.…”