Supported liquid membrane system for Cr(III) separation from Cr(III)/Cr(VI) mixtures

Area of Science:

• Environmental chemistry
• Separation science

Background:

• Chromium contamination poses significant environmental and health risks.
• Effective separation of chromium species is crucial for remediation and resource recovery.

Purpose of the Study:

• To investigate the transport of chromium(III) ions from Cr(III)/Cr(VI) mixtures using supported liquid membranes (SLMs).
• To evaluate the performance of dinonylnaphthalene sulfonic acid (DNNSA) and di(2-ethylhexyl) phosphoric acid (D2EHPA) as carriers in SLMs for chromium separation.

Main Methods:

• Utilized supported liquid membranes (SLMs) with DNNSA and D2EHPA carriers.
• Analyzed the transport of Cr(III) and Cr(VI) ions under varying conditions.
• Investigated the influence of Cr(VI) concentration and interaction time on Cr(III) separation.

Main Results:

• Both DNNSA and D2EHPA membranes acted as selective barriers for Cr(VI) ions.
• Increased Cr(VI) concentration and interaction time hindered Cr(III) separation due to carrier deactivation by Cr(VI).
• The DNNSA membrane was ineffective for Cr(III) separation from the mixture.
• The D2EHPA membrane demonstrated efficient Cr(III) transport under strict conditions (Cr(VI) < 10(-3)M, intensive mixing).

Conclusions:

• Supported liquid membranes can selectively barrier Cr(VI) ions.
• The D2EHPA-based SLM offers potential for Cr(III) separation but requires precise control over process parameters to mitigate Cr(VI) interference.
• Further optimization is needed for robust Cr(III) separation in complex chromium mixtures.