Extraction of arsenic-containing anions by supercritical CO"2 with ion-pairing [An article from: Chemical Engineering Journal]

This digital document is a journal article from Chemical Engineering Journal, published by Elsevier in 2005. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
The extraction of arsenic-containing anions from solid matrices by supercritical CO"2 (sc-CO"2) extraction coupled with ion-pairing was investigated. Tetra-butylammonium bromide (Bu"4NBr), tetra-hexylammonium bromide (Hex"4NBr), tetra-octylammonium bromide (Oct"4NBr), dodecyltrimethylammonium bromide (Dod(Me)"3NBr), myristyltrimethylammonim bromide (Myr(Me)"3NBr) and hexadecyltrimethylammonium bromide (Hex(Me)"3NBr) were used as the ion-pairing reagents. A model of the extraction of the arsenic-containing anions by supercritical CO"2 extraction with pre-ion-pairing was proposed, and verified with experimental results. The extraction efficiency depends on two parameters, which are the theoretical extraction efficiency (E"m"a"x) and the rate constant (k). The effects of the molecular structure and size of the ion-pair reagent on E"m"a"x and k were discussed. The process parameter effects on the extraction efficiency, including the temperature, pressure, the mole flow rate of CO"2, the mole ratio of alcohol to CO"2 and the dosage of the ion-pair reagent were investigated using But"4NBr and Myr(Me)"3NBr as the ion-pairing reagents.