Extraction of Cr (VI) by pickering emulsion liquid membrane using amphiphilic silica nanowires (ASNWs) as a surfactant

Abstract

Pickering emulsion is the replacement of surfactants with solid, often nano-sized particles. The particle-stabilized emulsions have good thermodynamic and kinetic stability. Pickering emulsion liquid membrane (PELM) was prepared using mahua oil as a diluent, aliquat 336 (Trioctyl methylammonium chloride) as a carrier and amphiphilic silica nanowires (ASNWs) (10–40 ml ethanol addition) as a surfactant. Sodium hydroxide (NaOH) was used as stripping phase in the concentration range from 0.1 to 0.5 M for the extraction of hexavalent chromium [Cr (VI)] from aqueous solution. The variety of edible and non-edible oils was investigated for the stability of water in oil emulsion. Factors that influence silica-stabilized Pickering emulsions are pH, agitation speed, stripping phase concentration, the volume ratio of membrane to stripping phase (M/S), initial feed concentration, treat ratio(feed to emulsion volume ratio) and surfactant concentration for better PELM stability. And also, the extraction efficiency of Cr (VI) was investigated using aliquat as a carrier. The physicochemical properties of ASNWs were studied using Scanning Electron Microscopy (SEM), Fourier Transforms Infrared Spectroscopy (FTIR) and Dynamic Light Scattering (DLS) techniques. At an optimum condition, 99.69% of Cr (VI) removal from aqueous solution was obtained.

Graphical Abstract

Keywords:

• ASNWs
• diluent
• extraction
• stripping phase
• surfactant

Acknowledgment

The authors wish to express their thanks to the financial support of Kerala State Council for Science, Technology and Environment (KSCSTE), Trivandrum, Kerala, India.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Kerala State Council for Science, Technology and Environment (Project Ref No: 69/SPS/60/2016/KSCSTE), Trivandrum, Kerala, India.