Self-assembly biochar colloids mycelial pellet for heavy metal removal from aqueous solution

To effectively improve the heavy metal removal efficiency and stability of biomass adsorbents, a novel biochar colloids-mycelial pellets (BC-MP) composite was prepared via a biological assembly method. BC-MP was successfully produced with increased surface area and multisorption sites by physical adsorption, electrostatic interaction and hydrogen-bond formation between BC and extracellular polymers on MP. To investigate the performance and mechanisms of heavy metal adsorption by BC-MP, batch experiments were conducted with cadmium (Cd (II)) as the model pollutant. Results showed that BC-MP had higher removal efficiency (57.66%) compared to BC (5.45%) and MP (38.45%), respectively, due to the synergistic effect. The maximum adsorption capacity of Cd (II) on BC-MP was 102.04 mg/g based on Langmuir isotherm model. Adsorption kinetics analysis indicated that chemical sorption was the key factor controlling the adsorption of Cd (II) onto BC-MP. Multiple characterization tests revealed that the main mechanisms of the adsorption process were surface complexation, cation exchange and precipitation. The BC-MP composite showed excellent heavy metal removal efficiency with long-term adsorption stability, suggesting its potential as a promising biosorbent for heavy metal removal from industrial wastewater.