Abstract
Low–cost biosorbents (ginkgo leaf, osmanthus leaf, banyan leaf, magnolia leaf, holly leaf, walnut shell, and grapefruit peel) were evaluated in the simultaneous removal of La3+, Ce3+, Pr3+, Nd3+, Sm3+, Eu3+, Gd3+, Yb3+, Lu3+, UO22+, Th4+, Y3+, Co2+, Zn2+, Ni2+, and Sr2+ from aqueous solutions. In single metal systems, all adsorbents exhibited good to excellent adsorption capacities toward lanthanides and actinides. In a simulated multicomponent mixed solution study, higher selectivity and efficiency were observed for Th4+ over other metal cations, with ginkgo leaves providing the highest adsorptivity (81.2%) among the seven biosorbents. Through optimization studies, the selectivity of Th4+ biosorption on ginkgo leaf was found to be highly pH–dependent, with optimum Th4+ removal observed at pH 4. Th4+ adsorption was found to proceed rapidly with an equilibrium time of 120 min and conform to pseudo–second–order kinetics. The Langmuir isotherm model best described Th4+ biosorption, with a maximum monolayer adsorption capacity of 103.8 mg g–1. Thermodynamic calculations indicated that Th4+ biosorption was spontaneous and endothermic. Furthermore, the physical and chemical properties of the adsorbent were determined by scanning electron microscopy, Brunauer–Emmett–Teller, X-ray powder diffraction, and Fourier transform infrared analysis. The biosorption of Th from a real sample (monazite mineral) was studied and an efficiency of 90.4% was achieved from nitric acid at pH 4 using ginkgo leaves.
Highlights
Thorium (Th) is a representative actinide metal element that is usually found alongside lanthanides and other transition metals in rocks and soil [1,2,3,4,5]
All biosorbents exhibited good to excellent adsorption capacities towards the lanthanides, Table 1
AAverage values for three independent adsorption experiments; precision corresponds to ± σn-1, where σn-1 is the standard deviation of the mean
Summary
Thorium (Th) is a representative actinide metal element that is usually found alongside lanthanides and other transition metals in rocks and soil [1,2,3,4,5]. The mineral monazite, the main mineral source of Th4+, is associated with lanthanum, cerium, samarium, yttrium, and other elements [6, 7]. The scientific importance and commercial value of Th has received much research attention because of its extensive use in various areas, including optics, radios, aeronautics, aerospace, metallurgy, chemical and nuclear industries, materials science [8,9,10,11,12], and nuclear medicine. Thorium (IV) biosorption from aqueous solution design, data collection and analysis, decision to publish, or preparation of the manuscript
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