Removal of copper ions from aqueous solution using low temperature biochar derived from the pyrolysis of municipal solid waste.

Sustainable methods to produce filter materials are needed to remove a variety of pollutants found in water including organic compounds, heavy metals, and other harmful inorganic and biological contaminants. This study focuses on the removal of Cu(II) from copper aqueous solutions using non-activated char derived from the pyrolysis of mixed municipal discarded materials (MMDM) using a new heat pipe-based pyrolysis reactor. Adsorption experiments were conducted by adding the char to copper solutions of varying concentration (50-250 mg/L) at a constant temperature of 30 °C. The effect of pH on copper adsorption onto the char was also investigated in the range of pH 3 to 6. Copper removal using the char was found to be heavily dependent on pH, adsorption was observed to decrease below a pH of 4.5. However, the initial copper concentration had a little effect on the sorption of copper at high concentration solutions (above 100 mg/L). Overall, the biochar showed an effective copper adsorption capacity (4-5 mg/g) when using copper solutions with a concentration below100 mg/L and pH >4.5. Copper removal using the char tended to follow the pseudo second order kinetic model. Langmuir isothermal model was shown to be the closest fitting isotherm using the linearized Langmuir equation. However, the variety of feedstock used to produce the char led to a variation in results compared to other studies of more specific feedstocks.