The influence of biomass species and pyrolysis temperature on carbon-retention ability and heavy metal adsorption property during biochar aging

The variation of heavy metals (HMs) adsorption characteristics and carbon retention efficiency during aging are indispensable for evaluating the effectiveness of biochar during the remediation of HMs contaminated soil, but the effect of aging on retention efficiency in multiple systems and correlation relation between preparation process and biochar characteristics are still not clear. In this study, the influence and correlation characteristic of biomass species, pyrolysis temperature on the carbon-retention ability and HMs adsorption property in both single and binary systems of lead and copper during aging were investigated. The results illustrated that the content of oxygen-containing functional groups increased by 21.90% for bamboo biochar (BBC), 39.65% for rice husk biochar (RHC) and 16.99% for corncob biochar (CSC) after aging, as well as the ratio of O/C and (O + N/C), whereas the ratio of H/C and pH decreased. RHC500 exhibited the best anti-aging and carbon-retention ability due to the high pyrolysis temperature and SiC coating layer formed. Furthermore, the functional group complexation and π bond interaction increased after aging, whereas the inorganic precipitation and ion exchange decreased, increasing the competitive adsorption capacity of Cu and decreasing the adsorption stability of HMs.