Insights into thallium adsorption onto the soil,bamboo-derived biochar,and biochar amended soil in Pomelo orchard

Little information is available on thallium(Tl)adsorption onto biochar amended soil for a relatively long term.In this study,bamboo-derived biochar(BDB),soil in pomelo orchard(SP),and biochar amended soil in pomelo orchard(BSP)were thus used to evaluate the potential remediation of thallium(Tl)using batch-adsorption techniques.Furthermore,we characterized the above-mentioned sorbents’properties related to Tl adsorption to understand Tl’s adsorption mechanisms.The results showed that BDB,SP,and BSP achieved equilibrium adsorption capacity of 96.9,95.43,and 96.76%,respectively,within the initial 15 min.This means that compared to other sorbents,BSP exhibited an efficient sorbent for Tl remediation even when applied in the agricultural field for one year.Multi-layer adsorption played a dominant role in the adsorption of Tl,which was supported by the suitability of Freundlich model for describing the adsorption behavior of Tl onto the selected sorbents.In addition,the pseudo-second kinetic order models strongly fitted Tl’s adsorption onto BDB,SP,and BSP,indicating that the process was accompanied by chemical adsorption.Observed on the surface of BDB by a Fourier Transform Infrared Spectrometer(FTIR)and an X-ray photoelectron spectroscopy(XPS),the presence of O-H groups and PO_(4)^(3−)might promote chemical adsorption of Tl onto BDB.Overall,these findings can provide insights into comprehensively developed bamboo-derived biochar technology to remediate Tl contamination in agricultural soils.