Electrically Controlled Adsorptive Membranes with Tunable Affinity for Selective Chromium (VI) Separation from Water

Area of Science:

• Materials Science
• Environmental Science
• Electrochemistry

Background:

• Hexavalent chromium (Cr(VI)) is a toxic ionic contaminant challenging water purification.
• Existing membrane technologies suffer from low permeability and selectivity for Cr(VI).

Purpose of the Study:

• To develop and evaluate an electrically controlled adsorptive membrane (ECAM-L) for efficient Cr(VI) separation.
• To investigate the Cr(VI) separation mechanisms using electrochemical and computational methods.

Main Methods:

• Fabrication of an ECAM-L using a Cl-doped polypyrrole layer on a carbon nanotube substrate.
• Electrochemical quartz crystal microbalance measurements.
• Molecular dynamics and density functional theory calculations.
• Performance evaluation for Cr(VI) removal, capacity, and water flux.

Main Results:

• ECAM-L demonstrated tunable adsorption/desorption of Cr(VI) via potential control, enabling cyclic use without additives.
• High Cr(VI) removal efficiency (<50 μg/L) and treatment capacity (>3500 L/m²).
• Achieved high water flux (283 L/m²/h) with membrane reusability.

Conclusions:

• The ECAM-L design provides an efficient method for water decontamination.
• Selective Cr(VI) separation is achievable through a brief electrical stimulus.
• This electrically controlled membrane offers a promising solution for Cr(VI) removal.