Removal of heavy metal ions from water using ion flotation

•Synthesis of several single-chain cysteine-based surfactants.•Determination of removal efficiency of heavy metal ions by ion flotation system.•Octanoyl-cysteine surfactant was found to be the most effective collector for heavy metal ions.

The effects of different single-chain surfactants obtained by reacting cysteine with octanoyl (C8), decanoyl (C10) and dodecanoyl (C12) chloride were investigated for their use in ion flotation removal of low levels of arsenic, mercury, lead, cadmium and chromium ions from aqueous solution. Re-crystallized octanoyl-cysteine (octanoyl-cys) surfactant showed the highest removal efficiency at 99.9%, for Hg ions, using pure nitrogen gas. Successful removal results of most other ions was found to be in the range 99.1-99.7%,using either air or nitrogen gas. Characterization of the octanoyl-cys surfactant was also carried out using elemental analysis, 1H NMR, FT-IR, melting point (MP) and critical micelle concentration (CMC) determination.

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