Calcium Silicate Hydrate Cation-Exchanger from Paper Recycling Ash and Waste Container Glass

Synthetic 11 Å tobermorite (Ca5Si6O16(OH)2.4H2O) and its Al-substituted analogue are layer-lattice ion-exchangers with potential applications in nuclear hazardous wastewater treatment. The present study reports the facile one-pot hydrothermal synthesis of an Al-tobermorite-rich cation-exchanger from a combination paper recycling ash, post-consumer container glass, lime, compositional ratios [Ca]/[Si + Al] = 0.81 [Al]/[Si 0.18. reaction products were characterized by powder X-ray diffraction analysis, 29Si magic angle spinning magnetic resonance spectroscopy, scanning electron microscopy. Hydrothermal processing 4 M NaOH(aq) at 100 °C for 7 days yielded product that also contained katoite (Ca3Al2SiO12H8), portlandite (Ca(OH)2), calcite (CaCO3), amorphous silicate gel. was found to have Cs+ cation exchange capacity 59 ± meq g−1 selective distribution coefficients (Kd) 574 13 658 34 cm3 solutions molar [Cs+]:[Na+] [Cs+]:[Ca2+] 1:100. In batch sorption 20 °C, uptakes Pb2+, Cd2+, determined be 1.78 0.04, 0.65 0.06, 0.36 0.03 mmol g−1, respectively. kinetics removal described pseudo-second-order rate model, which gave respective constants (k2) 0.010, 0.027, 1.635 g mmol−1 min−1, corresponding correlation (R2) 0.997, 0.996, 0.999. metal ion properties tobermorite-rich compared favorably those other waste-derived tobermorites reported literature. Potential strategies improve yield, crystallinity, characteristics discussed.