Tobermorite ion-exchanger from paper recycling ash and waste glass

Å tobermorite (Ca5(Si)6O16(OH)2.4H2O) and its Al-substituted counterpart are layer-lattice cation-exchangers that are of interest with respect to their applications in nuclear and hazardous wastewater treatment [1-3]. In 2015, the European Declaration on Paper Recycling reported that 71.5% of all paper consumed in Europe was recycled, corresponding to 1.2 million tonnes more than their 70% target [4]. Waste paper recycling ash (PRA) arising from this activity contains reactive calcium aluminosilicate phases that can be used for the hydrothermal synthesis of tobermorite when stoichiometrically adjusted with additional silicate-bearing reagents [1]. Waste soda-lime-silica container glass (SCG) has also been used as a partial feedstock for the preparation tobermorite in alkaline media [2]. This research tested the feasibility of a one-step synthesis of tobermorite from a combination of PRA and SCG under alkaline hydrothermal conditions at 100 °C. Reaction products were analysed by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). This study also evaluated the Cs+ cation-exchange capacity (CEC), selective Cs+ distribution coefficients (Kd, from Na+ and Ca2+ background solutions) and the uptake kinetics of Cd2+ and Pb2+ by the waste-derived tobermorite produc