Selective adsorption of Ga(III) via crosslinked pyrogallol resin: performance and mechanism

Gallium is a critical metal with low natural abundance, making its selective enrichment and separation essential for recycling. This study developed a crosslinked pyrogallol resin (PGNR) as a selective and reusable adsorbent for Ga(III) extraction. Under optimal conditions (318 K, pH = 9.0), PGNR achieved a maximum adsorption capacity of 89.3 mg·g - 1 . PGNR exhibited excellent selectivity, maintaining high efficiency even in multi-component systems containing As(V), Ca(II), and V(V). Notably, PGNR effectively mitigated V(V) interference, selectively adsorbing Ga(III) even when the V(V) concentration exceeded that of Ga(III) by more than fivefold. Reusability tests confirmed its practical value, with PGNR retaining over 85% of its adsorption capacity after five adsorption–desorption cycles. Isotherm analysis indicated monolayer adsorption consistent with the Langmuir model, while thermodynamic results confirmed the process was spontaneous and endothermic. Kinetic studies showed that the adsorption followed a pseudo-second-order model, dominated by chemisorption. FT-IR, XPS, and DFT analyses revealed that Ga(III) adsorption involved coordination with surface –OH groups and electrostatic interactions. These findings demonstrate that PGNR is a promising, efficient, and recyclable material for sustainable gallium extraction, particularly in challenging industrial environments such as Bayer liquor processing.