New Preparation of Inorganic Ion-exchangers by Reutilizing burned Waste Paper Sludges

Calcium silicate-containing ion-exchangers have been prepared by hydrothermal treatment of reutilizing burned waste paper sludges and cation-exchange characteristics of the prepared products have been investigated. According to the amounts of added CaO, SiO₂ and NaOH to the sludges, tobermorite and three types of zeolites (Analcime, Cancrinite and P-type Zeorite) were synthesized. Tobermorite was prepared at 0.7≦Ca/Si≦1.1, 0.15≦2Na/Si≦0.5 and mixed products (tobermorite and three types of zeolites) were prepared at 0.25≦Ca/Si≦0.4, 0.15≦2 Na/Si≦1.0 at 150~175 °C. Cation-exchange characteristics of Ca²⁺ ions in the prepared products for Cs⁺, Co²⁺ and Zn²⁺ ions in aqueous solution have been investigated at room temperature and atomospheric pressure, using a normal batch method. The prepared tobermorite product was found to easily ion-exchange the lattice Ca²⁺ ions in layer structure for Co²⁺ and Zn²⁺ ions in aqueous solution at room temperature and atomospheric pressure, ie, the product was found to be a “lattice ion ion-exchanger” introduced by one of the authors, Suzuki. From the results, it can be concluded that the synthetic compounds prepared from the burned waste paper sludges have been available for an ion-exchanger.