Thallium separation from wastewater using α-FeOOH@Biochar: Efficacy and mechanism

KOH-modified bamboo charcoal loaded with α-FeOOH for efficient adsorption of copper and fluoride ions from aqueous solution

“…5 The peaks at 1580 cm −1 and 1364 cm −1 are respectively related to the tension of –COOH and symmetric stretching of the carboxyl group, and peaks at 877 cm −1 and 815 cm −1 are attributed to the extension and in-plane bending of surface hydroxyl groups on α-FeOOH. 52 After Cu 2+ and F − adsorption, these peaks underwent corresponding changes. During Cu 2+ adsorption, the oxygen atoms in –OH and –COOH groups share their non-bonding electron pairs with Cu 2+ , thereby reacting to form surface complexes (such as COO–Cu, Fe–O–Cu, C–O–Cu) and substituting H in these groups.…”

“…60 In addition, the peak at 613 cm −1 is attributed to Fe–O bending vibrations. 52 After Cu 2+ adsorption, the peak weakens, preliminarily indicating that Cu may replace some Fe in α-FeOOH. Moreover, after the F − adsorption, the peak at 613 cm −1 changes slightly, and a new absorption peak appears at 467 cm −1 , possibly due to Fe–F formation.…”

“… 37 The linear curves do not traverse the origin, revealing that the adsorption rate is determined by intraparticle-dispersion and physical and chemical processes. 52 …”

“…Cu 2+ and F − may have rst diffused on the FKBC surface at a high rate and then diffused into micropores at a lower rate 37. The linear curves do not traverse the origin, revealing that the adsorption rate is determined by intraparticle-dispersion and physical and chemical processes 52.…”