Na2co3

Poly(sodium 4‐styrenesulfonate) (PSS, average molecular weight ≈ 1 000 000 and ≈ 70 000) was purchased from Sigma‐Aldrich (USA). Polyethylenimine (PEI, branched, linear formula: (CH₂CH₂NH)_n, average molecular weight ≈ 70 000, 50 wt% in H₂O), a Fe₃O₄ nanoparticle suspension and UO₂(NO₃)₂·6H₂O were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd (China). Ethanol (anhydrous, purity of 99.5%), HCl, Na₂CO₃, concentrated nitric acid and NaCl (purity of 99.5%) were obtained from Sinopharm Chemical Reagent Co., Ltd (China). Deionized water was purified by a ULUP water purification system with a minimum resistivity of 18.25 mΩ cm⁻¹ and used in all the processes. A stock solution of U(IV) (1000 mg L⁻¹) was prepared by dissolving UO₂(NO₃)₂·6H₂O in concentrated nitric acid (2 mL) and deionized water (98 mL). The stock solution was then diluted to a desired concentration prior to the uranium adsorption experiment with the pH being adjusted by Na₂CO₃.

All chemicals and reagents used were of analytical grade. The water was double distilled (ddH₂O). Methanol and acetonitrile of chromatographic purity were purchased from Sigma-Aldrich (St. Louis, MO, USA). N-hexane, ethyl acetate, gallic acid, NaOH, Folin–Ciocalteu, Na₂CO₃, Trolox, 2,2-diphenyl-1-picrylhydrazyl (DPPH), FeCl₃, HCl, NaAc, and 2,4,6-tris (2-pyridyl)-s-triazine (TPTZ) were purchased from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China).

The KNN piezoelectric ceramic powder was synthesized by solid state reaction using the raw materials of sodium carbonate (Na₂CO₃, 99.8%, Sinopharm Chemical Reagent Co. Ltd., Shanghai, China), potassium carbonate (K₂CO3, 99.0%, Sinopharm Chemical Reagent Co. Ltd., Shanghai, China), and niobium oxide (Nb₂O₅, 99.9%, Shanghai Aladdin, Shanghai, China) at the mole ratio of r(K:Na:Nb) = 0.5:0.5:1. After drying at 120 °C for 5 h, the raw materials were weighed and added to a Teflon bottle along with agate balls of 6 mm and 10 mm in diameter. The ratio of powder mixtures to balls to liquid was approximately 1:4:4 by mass. Then the mixtures were ball-milled by planetary using ethanol as medium for 4, 8 and 16 h, respectively. The dried mixtures were calcined in an alumina crucible at different temperature of 600, 700, 800, and 900 °C for 2 h, respectively. Adding 8 wt % of polyvinyl alcohol as binder, the calcined powder mixtures were then die-pressed into discs (diameter 10 mm, thickness 3 mm) under 150 MPa without second ball milling and sintered in air at 1050 °C for 2 h in a loosely-covered Al₂O₃ crucible.

The cation exchange membranes and anion exchange membranes used in the experiments were CJ-MC-3 and CJ-MA-2, respectively (Hefei ChemJoy Polymers Co., Ltd., Hefei, China). The main properties of the ion exchange membranes are listed in Table 3. Before the experiments, the cation and anion exchange membranes were immersed in a 0.5 mol·L⁻¹ NaCl solution for 24 h to change them into corresponding Na⁺ and Cl⁻ form. The reagents used in the study, including NaCl, NH₄Cl, NaHCO₃, Na₂CO₃, K₃[Fe(CN)₆], and K₄[Fe(CN)₆], were all analytical grade and purchased from Sinopharm Chemical Reagent Co., Ltd., Shanghai, China. Deionized water was used throughout the experiments.

The PG with the nominal composition (in mol%) of SANGL was prepared via the conventional melt-quenching route. The analytical-grade reagents of SiO₂ (Sinopharm Chemical Reagent Co., Ltd), Al₂O₃ (Sinopharm Chemical Reagent Co., Ltd), Na₂CO₃ (Sinopharm Chemical Reagent Co., Ltd), Ga₂O₃ (Nanjing Xinuo Tech. Co., Ltd), Li₂CO₃ (Sinopharm Chemical Reagent Co., Ltd) and MnCO₃ (Sinopharm Chemical Reagent Co., Ltd) were weighed, mixed and ground as raw materials in an agate mortar. The obtained mixtures were then placed in a sealed alumina crucible and melted at 1640 °C for 30 min under ambient atmosphere. Subsequently, the glass melt was poured into a 300 °C preheated copper mould and annealed at 450 °C for 5 h to relinquish the internal stress. Ultimately, the obtained bulk glasses were cut into square coupons, polished and heat treated at 750 °C for different periods of time to induce crystallization of the LiGa₅O₈ nanophase.