<p>Biochar (BC) has been widely used for the lead (Pb(II)) immobilization in soil remediation. However, the mechanisms of dissolution-driven removal of Pb(II) by BC are still poorly understood. Herein, Pb(II) removal was investigated by differentiating BC- and dissolved organic carbon (DOC)-systems. As per the kinetics and isotherms, Pb(II) removal ranged from 31.11% to 80.92% in BC-system. This removal process was significantly influenced by dissolution-driven precipitation which contributed from 23.42% to 84.03% in DOC-system. During Pb(II) removal, an obvious reduction was observed in the released inorganic anions including carbonate (CO<sub>3</sub><sup>2−</sup>), sulfate (SO<sub>4</sub><sup>2−</sup>), and phosphate (PO<sub>4</sub><sup>3−</sup>). The CO<sub>3</sub><sup>2−</sup> was a predominant contributor to facilitate Pb(II) precipitation. X-ray diffraction further confirmed the formation of cerussite (PbCO<sub>3</sub>) and anglesite (PbSO<sub>4</sub>) on BC surface after Pb(II) removal. Moreover, the decreased fluorescence responses of humic-like and fulvic-like substances were detected in DOC-system with the addition of Pb(II). At the same anion concentration, the enhanced Pb(II) amount was removed with increasing DOC concentration from 1 mg·L<sup>− 1</sup> to 5 mg·L<sup>− 1</sup>. These results indicated that released DOC exerted a significant contribution on Pb(II) precipitation due to its coagulation effect. This research provides mechanistic insights into the contributions of adsorption and dissolution-driven precipitation in overall Pb(II) removal through BC application.</p>

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Quantitative contribution of dissolution-driven precipitation to Pb(II) removal by biochars during adsorption process

  • Anila Sikandar,
  • Jing Zhao,
  • Shakeel Ahmad,
  • Gang Chu,
  • Bo Pan,
  • Zhaofeng Chang,
  • Yang Liu,
  • Danping Wu,
  • Audil Rashid

摘要

Biochar (BC) has been widely used for the lead (Pb(II)) immobilization in soil remediation. However, the mechanisms of dissolution-driven removal of Pb(II) by BC are still poorly understood. Herein, Pb(II) removal was investigated by differentiating BC- and dissolved organic carbon (DOC)-systems. As per the kinetics and isotherms, Pb(II) removal ranged from 31.11% to 80.92% in BC-system. This removal process was significantly influenced by dissolution-driven precipitation which contributed from 23.42% to 84.03% in DOC-system. During Pb(II) removal, an obvious reduction was observed in the released inorganic anions including carbonate (CO32−), sulfate (SO42−), and phosphate (PO43−). The CO32− was a predominant contributor to facilitate Pb(II) precipitation. X-ray diffraction further confirmed the formation of cerussite (PbCO3) and anglesite (PbSO4) on BC surface after Pb(II) removal. Moreover, the decreased fluorescence responses of humic-like and fulvic-like substances were detected in DOC-system with the addition of Pb(II). At the same anion concentration, the enhanced Pb(II) amount was removed with increasing DOC concentration from 1 mg·L− 1 to 5 mg·L− 1. These results indicated that released DOC exerted a significant contribution on Pb(II) precipitation due to its coagulation effect. This research provides mechanistic insights into the contributions of adsorption and dissolution-driven precipitation in overall Pb(II) removal through BC application.