Dissolved organic matters-enhanced Pb releases from nano- or submicron Pb sulfides and oxides

Authors：Kong, Yu; Zhao, Bing; Zhao, Jingjing; Lei, Lei; Zhao, Qing; Zhang, Xuejiao; Li, Haibo; Sun, Hongyu; Zhang, Siyu^*

Source：Science of the Total Environment, 2022, 850: 157972.

DOI：10.1016/j.scitotenv.2022.157972

• Pb particles
• Dissolved organic matters
• Dissolved Pb
• Ligand exchange
• DFT calculation

Diverse lead (Pb) particles possess different ecological risks not only due to their own toxicity differences but also be-cause of different abilities to release toxic dissolved Pb. Dissolved organic matter (DOM) was a key factor influencing dissolution processes of metal particles. However, impacts of DOM on dissolution of different Pb nano-or submicron particles were not known yet. Herein, impacts of DOM on dissolution kinetics of lead sulfide (PbS), lead sulfate (PbSO4), lead monoxide (PbO), lead tetroxide (Pb3O4) and lead dioxide (PbO2) nano-or submicron particles were firstly investigated taking Pahokee Peat humic acid (PPHA) as an example. Results indicated PPHA improved the suspending stability of Pb particles through electrostatic repulsion, and enhanced releases of dissolved Pb. Final con-centration of dissolved Pb was raised by 1.22-8.82 times with PPHA. This was attributed to ligand exchange interac-tions between PPHA and Pb particles. Theoretical computations indicated that not only sorption or ligand exchange energy, but also numbers of ligands on the surface of particles were key factors governing impacts of PPHA on dis-solved Pb. This study provided a new mechanism insight into dissolution behavior of various Pb particles and will be beneficial to their ecological risk assessment.

• Institution
  江南大学; 东北大学; 中国科学院