Facile and clean separation of Pb(II) from soil and recycling by pH-triggered microbial technology

Developing an efficient method to recover and reuse soil-base lead (Pb) poses significant challenges. Herein, we designed a remediation method to achieve the dual goal of separating and reusing Pb from soil based on Bacillus megaterium-secreted surfactin with pH-response. Under weakly alkaline, B. megaterium-secreted surfactin efficiently captured Pb(II) from soil and also converted it into biological Pb/PbO nanoparticles (bio-Pb/PbO NPs). Further, surfactin's sensitivity to pH enables bio-Pb/PbO NPs to be readily separated from the soil through simple pH adjustments. The highest yield of bio-Pb/PbO NPs (77.54%) was achieved at an initial concentration of 1 mg/g Pb(II). The recovered bio-Pb/PbO NPs showed a mesoporous structure and an average size of similar to 47 nm. More importantly, bio-Pb/PbO NPs exhibited highly efficient catalytic activity for the hydrogen evolution reaction in 1 M KOH. These results demonstrated that this method efficiently recovered and converted Pb into high valueadded NPs, and was thereby a sustainable and feasible technique for Pb(II) recovery and reuse. As such, this methodology offers a new, efficient, and practical approach for sustainable remediation of heavy metal contamination in soils.