Metals removal from aqueous solution by iron-based bonding agents.
GOAL AND SCOPE AND BACKGROUND: The application of a promising method, termed sorptive flotation, for the removal of chromium(VI) and zinc ions was the aim of the present paper. A special case of sorptive flotation is adsorbing colloid flotation. Suitable sorbent preparation techniques have been developed in the laboratory.


METHODS
Sorptive flotation, consisting of the sorption and flotation processes combined in series, has proved to give fast and satisfactory treatment of the industrial streams and effluents bearing dilute aqueous solutions of zinc and chromium(VI).


CONCLUSIONS
Goethite has proved to be effective for the removal of chromium(VI) and zinc ions. Also, adsorbing colloid flotation with ferric hydroxide (as the co-precipitant) could be an alternative method to the above-mentioned separation of metal ions. In both cases, chromium(VI) (pH=4) and zinc (pH=7) removal was about 100%.


CONCLUSIONS
The reasons for selecting the iron-based bonding materials, like goethite and/or in-situ produced ferric hydroxide, are that they are cheap, easily synthesized, suitable both for cation and anion sorption, and, furthermore, that they present low risks for adding a further pollutant to the system. Promising results were obtained.


CONCLUSIONS
The application of goethite and in-situ produced ferric hydroxide has demonstrated their effectiveness in the removal of heavy metal ions, such as chromium anions and zinc cations. A proposed continuation of current work is the utilization of similar iron oxides, for instance synthesized akaganeite. The comparison between the results reported in this paper with the results reported in the literature, also deserves attention.
Deliyanni
Eleni A
EA
Laboratory of General & Inorganic Chemical Technology, School of Chemistry, Aristotle University, GR-54124 Thessaloniki, Greece.
Lazaridis
Nikolaos K
NK
Peleka
Efrosini N
EN
Matis
Konstantinos A
KA
D000327:Adsorption; D002857:Chromium / Q000737:chemistry*; D003102:Colloids; D005290:Ferric Compounds / Q000737:chemistry; D005296:Ferrous Compounds / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D058085:Iron Compounds / Q000737:chemistry; D008903:Minerals; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000379:methods*; D015032:Zinc / Q000737:chemistry*
D003102:Colloids; D005290:Ferric Compounds; D005296:Ferrous Compounds; D058085:Iron Compounds; D008903:Minerals; D014874:Water Pollutants, Chemical; D002857:Chromium; C094886:goethite; C021024:ferric hydroxide; D015032:Zinc