An Innovative Geopolymer Composite Insulation Material Based on Phytoremediation Biowaste: Solidification/Stabilization of Potentially Toxic Metals

Phytoremediation biowaste without proper disposal might release potentially toxic metals (PTMs) back into the environment and pose a serious threat to environmental safety and human health.A composite geopolymer based on phytoremediation biowastes (PBWs) was used to effectively solidify/stabilize toxic heavy metals and served as an insulation material in the present study.For the solidification/stabilization of PTMs, the optimum proportion of biowastes in the geopolymer insulation material was 3%, at which the compressive strength of the geopolymer reached a maximum of 32.6 MPa and the thermal conductivity of the geopolymer was 0.11 W/(m•K), meeting the requirements of insulation materials.The leaching results indicated that the solidification efficiency of PTMs in the geopolymer materials was over 98%.The leaching concentration of all samples was within the standard limits and decreased with the extension of curing time.The XRD and FT-IR spectra of the biowaste-geopolymer confirmed the effective solidification/stabilization of PTMs in the geopolymer composite, where Zn was immobilized as carbonate and silicate.The geopolymer technique can stabilize the PTMs and prepare insulation materials simultaneously.Hence, this research provided a helpful insight and theoretical support for the post-treatment and the reutilization of plant waste accumulated with heavy metals.