Adsorption-desorption characteristics and mechanisms of Pb(II) on natural vanadium, titanium-bearing magnetite-humic acid magnetic adsorbent

Lead (Pb) ions are chronically detected in soil, underground and natural water, there is a need for low-cost in situ remediation techniques. A novel mineral based magnetic adsorbent, consisting of natural vanadium, titanium-bearing magnetite particles coated by humic acid (abbr. VTM-HA), was developed for removing Pb(II) from wastewater. In this study, adsorption-desorption characteristics and mechanisms of Pb (II) on the VTM-HA adsorbent were investigated. The regeneration and reuse feasibility of the VTM-HA adsorbent were also conducted. The adsorption tests further verified that Pb(II) was removed rapidly and efficiently by the VTM-HA adsorbent. Moreover, Pb (II) adsorbed on the VTM-HA adsorbent could be easily eluted using a small amount of acidic eluent, and the desorption of Pb (II) could reach 99.3 wt% in 0.1 M HNO3 (pH = 1). After five adsorption-desorption regeneration cycles, the magnetism and Pb(II) adsorption capacity of the regenerated VTM-HA adsorbent almost kept unchanged. The results indicated that the VTM-HA adsorbent had excellent adsorption capacity and regenerative ability, which could be used as ideal adsorbents for removing Pb (II) from acid wastewater in commercial application. The mechanisms of Pb (II) adsorption and desorption were explored by FTIR, XPS analysis and DFT calculation. (C) 2019 Elsevier B.V. All rights reserved.