Development of a triazine-pyrone Schiff base methacrylate adsorbent for the selective recovery of beryllium ions from hazardous industrial sludge.

The extreme hydration, small ionic size, and high charge density of Be2+ ions make their recovery from hazardous industrial sludge a challenge, raising environmental concerns. Using a newly developed method, we synthesized triazine-pyrone Schiff base methacrylate (TP-SB-MA), a new chelating adsorbent, and evaluated its effectiveness for Be2+ separation. A two-step process was employed to synthesize TP-SB-MA. The first step involved changing the Schiff base from 1,3,5-tris(4-aminophenyl)triazine to 3-acetyl-4-hydroxy-6-methyl-2H-pyran-2-one. Then, a urethane link was used to functionalize the methacrylate. The material primarily displays nitrogen and oxygen donor sites, and its pore size ranges from 0.8 to 1.3 nm. The network of persistent micropores is another feature. The data fitted the Langmuir isotherm model (q m = 169.56 mg g-1) with the highest R 2 value and the lowest SSE and χ 2 values among the isotherm models studied, consistent with the monolayer surface coverage; together with the pseudo-second-order kinetics and Dubinin-Radushkevich adsorption energy, this supports a chemisorption-dominated uptake mechanism. Batch adsorption experiments demonstrated an experimental maximum capacity of 165.7 mg g-1 at pH 3.5, with a theoretical monolayer capacity of up to 175.19 mg g-1 predicted by Dubinin-Radushkevich isotherm modeling, and the equilibrium period was approximately 30 minutes. The spontaneous endothermic reaction (ΔH° = +9.0 kJ mol-1; ΔG° < 0) was demonstrated by the thermodynamic results. FTIR spectroscopic and XPS analyses provided converging evidence that the imine, carbonyl, and urethane groups were directly involved in Be2+ binding. Under optimal elution conditions (0.4 M H2SO4), TP-SB-MA achieved a desorption efficiency of 87.15% and retained approximately 80% of its adsorption capacity after 9 cycles, demonstrating its high reusability, as confirmed by post-cycling XPS, which revealed the retention of both its Schiff-base structure and Be2+-coordinating sites. The acid leaching of real sludge, followed by TP-SB-MA adsorption, selective acid stripping, and pH-controlled precipitation-calcination, successfully recovered wurtzite-phase BeO with an experimentally verified chemical purity of 98.48 ± 0.33 wt% (confirmed by PXRD and ICP elemental assay). This study is the first to show that methacrylate-tuned Schiff base chelating ligands may be used for beryllium remediation and sustainable high-scopic recovery as a part of a circular resource management strategy.