“One-can” strategy for the synthesis of hydrothermal biochar modified with phosphate groups and efficient removal of uranium(VI)

A Review on the Removal of Heavy Metals from Water by Phosphorus-Enriched Biochar

“…It increases steric hindrance and intensifies competition for available adsorption sites, ultimately leading to a decline in the adsorption capacity for heavy metal ions [41,82].The ion strength significantly associated with adsorption capacity can prove the mechanism underlying the capture of heavy metal ions is governed by either ion exchange or outer-sphere complexation. Conversely, if the correlation is absent, it substantiates that the primary mode of heavy metal adsorption onto the surface of PBC is through inner-sphere complexation [73]:…”

“…The electrostatic interaction between heavy metals and PBC is influenced by pH and zeta potential. When the pH exceeds the point of zero charge (ZPC), deprotonation results in a negatively charged surface on the PBC, allowing for the capture of heavy metal cations through electrostatic interaction [73]. As the pH increases, the absolute value of the zeta potential also increases, leading to an enhanced attraction between PBC and positively charged heavy metal cations.…”

“…− and UO 2 (OH) 3 − . Due to the weak Coulombic effect, the electrostatic adsorption performance of PBC diminishes [73], and divalent heavy metals also gradually precipitate as hydroxides [39].…”

“…The incorporation of phosphorus further enhances the aromatization of PBC compared to the original biochar and improves its ability to act as an electron donor [41]. The intensity of characteristic peaks of the aromatic C-H bond and the H/C value are crucial indicators for evaluating the degree of aromatization [73,77].…”