Regulating Ga(III) Capture and Selectivity by O-Donor Coordination Environments in Functionalized Conjugated...

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Selective gallium (Ga(III)) enrichment from acidic zinc hydrometallurgical solutions is difficult due to low concentrations and competing ions.
• Existing methods struggle with efficiency and selectivity in complex matrices.

Purpose of the Study:

• To develop and compare novel functionalized porous polymers for selective Ga(III) adsorption.
• To investigate the influence of different oxygen-donor coordination environments on Ga(III) binding.
• To evaluate the performance of these materials for gallium recovery in simulated industrial conditions.

Main Methods:

• Post-synthetic modification of a conjugated microporous polymer (CMP-mCOOCH3) to create hydroxamic acid (CMP-mCONHOH) and carboxyl (CMP-mCOOH) functionalized materials.
• Ga(III) adsorption experiments under acidic conditions (pH 3, 298 K) with varying coexisting metal ions (Al(III), Zn(II), Cu(II), In(III)).
• Kinetic (pseudo-second-order) and isotherm (Langmuir) modeling, adsorption-desorption cycling, spectroscopic analysis, and theoretical calculations.

Main Results:

• Both CMP-mCONHOH and CMP-mCOOH demonstrated efficient Ga(III) uptake with capacities of 174.75 mg g⁻¹ and 249.47 mg g⁻¹, respectively.
• Adsorption followed Langmuir isotherm and pseudo-second-order kinetics, indicating monolayer adsorption driven by coordination.
• CMP-mCOOH showed higher capacity, while CMP-mCONHOH offered superior Ga/In separation, with both materials retaining over 90% efficiency after five cycles.

Conclusions:

• Functionalized conjugated microporous polymers are effective and regenerable adsorbents for Ga(III) recovery from acidic solutions.
• Oxygen-donor coordination is the primary mechanism for Ga(III) binding.
• The tailored design of porous polymers offers a promising strategy for selective metal ion separation in hydrometallurgy.