Removal of arsenic from contaminated water by foam flotation

Z. Pan, L. Zhang and P. Somasundaran*

NSF-Industry/University Cooperative Research Center for Advanced Studies in Novel Surfactants, Langmuir Center for Colloids and Interfaces, Columbia University, New York, N Y 10027, U.S.A.

Received 23 January 2002; accepted 18 June 2003


Foam flotation has been employed in this work for enhanced removal of arsenic species from water. The method involves interactions between arsenic species or arsenic-hydrolysable multi-cation complexes and surfactants, and removal of the hydrophobic complexes formed by air bubbles under quiescent conditions. The system in our experiments consisted of arsenic(V) oxide hydrate, aluminum chloride, sodium dodecyl sulfate (CH3(CH2)11OSO3Na), dodecylamine (CH3(CH2)11NH2), and frothers. It was found that as much as 99% removal of arsenic species can be obtained by adsorbing colloid flotation, the removal being depended upon the solution pH, the ratio of arsenic to aluminum chloride and the interactions between the arsenic-multication species and the surfactants used as collectors. The low removal (less than 10%) of arsenic species by ion flotation in our experiments suggests that the interactions between arsenic species and oppositely charged surfactants may be weak, and therefore an activator is needed to transform arsenic species into more ionic forms for the ionic flotation of arsenic species. These results show that flotation based on the interactions between arsenic-multication species and surfactants is a new effective method either by itself or in combination with other techniques for the removal of arsenic from effluents.

Keywords: Arsenic removal; Foam flotation; Aluminum chloride; Surfactants

* Corresponding author
   E-mail : ps24@columbia.edu