Gallium extraction from Bayer liquor using hydroxamic acid-functionalized poly(ethyl acrylate) adsorbents with oriented porous structures.

As a waste resource from the aluminum industry, Bayer liquor contains a large amount of gallium (Ga) ions. The recovery of Ga from Bayer liquor is of great significance for resource utilization and obtaining high-value metals. Poly(ethyl acrylate) (PEA) with an oriented porous structure was prepared by the ice-templating method. Hydroxamic acid groups were grafted onto the pore surfaces to construct specific adsorption sites, forming efficient mass transfer channels and abundant specific functional groups. The novel PEA adsorbent, which contained regular vertically arranged oriented pores, had a specific surface area as large as 10.96 m2 g-1 available for metal adsorption. Its rich hydroxamic acid groups were evenly distributed within the adsorbent. The extensive chelation of Ga(iii) was achieved on the surface of the pores, exhibiting excellent adsorption performance. In the simulated Bayer liquor, the equilibrium adsorption capacity for Ga(iii) reached 27.35 mg g-1. The adsorption followed a chemisorption mechanism with homogeneous monolayer characteristics. The porous PEA adsorbents also exhibited excellent adsorption performance over a wide concentration range. In the real Bayer liquor containing coexisting ions such as vanadium, the equilibrium capacity slightly decreased to 19.46 mg g-1 due to competitive adsorption. This work provides a novel strategy for designing high-performance porous adsorbents for Ga recovery in complex industrial wastewater systems.