Adsorption-pyrolysis technology for recovering heavy metals in solution using contaminated biomass phytoremediation

- Adsorption-pyrolysis technology by phytoremediation biomass was proposed for recovery the heavy metals Cd and Cu from soil and solution.
- Heavy metals in the biomass were mainly retained in the solid products after pyrolysis and the content of heavy metals was more than 6.58 wt%.
- Compare with Cu, Cd in biomass was more volatilized under 950 °C while both of them can be recovered under 450 °C.

Feasibility of adsorption-pyrolysis technology to recover metals from solution using contaminated biomass phytoremediation was discussed. The technology can meet three objectives: the disposal of metals-contaminated biomass from phytoremediation, the adsorption of metals from wastewater and the reuse of metals-saturated biomass. In this study, the recovery of Cd and Cu in metals-containing solution from contaminated biomass of phytoremediation was achieved through adsorption and pyrolysis technology. The results showed that pH value of the metals-containing solution and the pyrolysis temperature for metals concentration are the key factors of the novel technology. When the pH of the metals-containing solution was 6, the content of Cd and Cu in the saturated biomass after approximately 30 min adsorption was 2.7 wt% and 1.25 wt%. Next, the saturated biomass is pyrolyzed at 450 °C, and the final content of Cd and Cu in the solid phase product was 7.13 wt% and 6.58 wt%, respectively. The concentration of metals from the adsorption-pyrolysis process for bio-ore was primarily due to the redox reaction of Cd and Cu salts and the volatilizing properties of elements. The results suggested that the adsorption-pyrolysis technology is feasible for recovery of Cd and Cu in solution.