New insights into the interactions between Pb(II) and fruit waste biosorbent

Qian Wang*, Yunlong Wang, Junjie Tang, Zi Yang, Li Zhang, Xiaowu Huang*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Fruit waste is a sustainable biosorbent for heavy metal removal from wastewater. Elucidation of adsorption mechanism is imperative for the process control and development of effective adsorbents. In this study, watermelon rind (WR) exhibited selective and efficient Pb(II) adsorption with a maximum uptake of 230.5 mg/g at pH 5.0. The WR-packed bed column showed high Pb(II) uptake and robust durability over 10 adsorption-desorption cycles with long breakthrough time of 8–13 h (89–144 bed volume), and 95% of sequestered Pb(II) was rapidly desorbed in 1–2 h by 0.05 M HCl. Spectroscopic characterization by FTIR and XPS identified hydroxyl, carboxyl, amine, and ether groups as the binding sites for Pb(II) via the binding force of complexation. Physicochemical analysis showed that ion exchange with Mg2+ and Ca2+ accounted for 19% of Pb(II) adsorption by WR; electrostatic attraction and microprecipitation jointly contributed. Quantum chemistry simulation verified the interactions between Pb(II) and binding sites and revealed carboxyl was the preferential functional group. The findings corroborate the applicability of WR in scale-up Pb(II) removal/recovery from wastewater and elaborate the mechanisms of Pb(II) adsorption by the WR-biosorbent. This also provides insights into the behavior of heavy metals in other liquid/solid interfaces.
Original languageEnglish
JournalChemosphere
DOIs
StateE-pub ahead of print - 22 May 2022

Keywords

  • Fruit waste
  • Heavy metal
  • Adsorption mechanism
  • Column study
  • Circular economy

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