17 / 2021-06-23 09:46:48

An innovative geopolymer composite insulation material based on phytoremediation plant wastes: Solidification/stabilization of potentially toxic metals (PTMs)

Phytoremediation plant wastes; Potentially toxic metals; Geopolymer; Solidification/stabilization; Insulation

In this study, a composite geopolymer based on the phytoremediation plant wastes (PPWs) was used to effectively solidify/stabilize toxic heavy metals (Cd, Pb, and Zn) and can be applied as insulation material. The optimum proportion of biowastes in the geopolymer insulation material for the solidification/stabilization of potentially toxic metals (PTMs) was 3%, of which the compressive strength reached a maximum of 32.6 MPa and the thermal conductivity was 0.11 W/(m·K) meeting the requirements of insulation material. The leaching results indicated that the solidification efficiency of PTMs in the geopolymer materials was over 98%. The leaching concentration of PTMs decreased with the extension of curing time, which were all below the standard limits. The XRD and FT-IR spectra of the biowaste-geopolymer confirmed the solidification/stabilization of PTMs in the geopolymer composite, where Zn was immobilized as carbonate and silicate. The solidification/stabilization mechanism of Cd and Pb was complicated, involving the charge balance, silicate formation, and physical encapsulation. The geopolymer technique can stabilize the PTMs and prepare insulation materials simultaneously. Hence, this research provided a helpful insight and important theoretical support for the post-treatment and the reutilization of plants waste accumulated with heavy metals.