| Summary: | Synthetic 11 Å tobermorite (Ca<sub>5</sub>Si<sub>6</sub>O<sub>16</sub>(OH)<sub>2</sub>.4H<sub>2</sub>O) and its Al-substituted analogue are layer-lattice ion-exchangers with potential applications in nuclear and hazardous wastewater treatment. The present study reports the facile one-pot hydrothermal synthesis of an Al-tobermorite-rich cation-exchanger from a combination of paper recycling ash, post-consumer container glass, and lime, with compositional ratios of [Ca]/[Si + Al] = 0.81 and [Al]/[Si + Al] = 0.18. The reaction products were characterized by powder X-ray diffraction analysis, <sup>29</sup>Si magic angle spinning nuclear magnetic resonance spectroscopy, and scanning electron microscopy. Hydrothermal processing in 4 M NaOH<sub>(aq)</sub> at 100 °C for 7 days yielded an Al-tobermorite-rich product that also contained katoite (Ca<sub>3</sub>Al<sub>2</sub>SiO<sub>12</sub>H<sub>8</sub>), portlandite (Ca(OH)<sub>2</sub>), calcite (CaCO<sub>3</sub>), and amorphous silicate gel. The hydrothermal product was found to have a Cs<sup>+</sup> cation exchange capacity of 59 ± 4 meq 100 g<sup>−1</sup> and selective Cs<sup>+</sup> distribution coefficients (<i>K<sub>d</sub></i>) of 574 ± 13 and 658 ± 34 cm<sup>3</sup> g<sup>−1</sup> from solutions with molar ratios [Cs<sup>+</sup>]:[Na<sup>+</sup>] and [Cs<sup>+</sup>]:[Ca<sup>2+</sup>] of 1:100. In a batch sorption study at 20 °C, the uptakes of Pb<sup>2+</sup>, Cd<sup>2+</sup>, and Cs<sup>+</sup> were determined to be 1.78 ± 0.04, 0.65 ± 0.06, and 0.36 ± 0.03 mmol g<sup>−1</sup>, respectively. The kinetics of Pb<sup>2+</sup>, Cd<sup>2+</sup>, and Cs<sup>+</sup> removal were described by the pseudo-second-order rate model, which gave respective rate constants (<i>k</i><sub>2</sub>) of 0.010, 0.027, and 1.635 g mmol<sup>−1</sup> min<sup>−1</sup>, and corresponding correlation coefficients (<i>R</i><sup>2</sup>) of 0.997, 0.996, and 0.999. The metal ion sorption properties of the tobermorite-rich product compared favorably with those of other waste-derived tobermorites reported in the literature. Potential strategies to improve the yield, crystallinity, and sorption characteristics of the product are discussed.
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