Adsorption of Uranium(VI) from Aqueous Solution by Modified Rice Stem

Abstract

The biosorption is an effective and economical method to deal with the wastewater with low concentrations of uranium. In this study, we present a systematic investigation of the adsorption properties, such as the kinetics, thermodynamics, and mechanisms, of modified rice stems. The rice stems treated with 0.5 mol/L NaOH solutions show higher removal percentage of uranium than those unmodified under the conditions of initial pH (pH = 4.0), absorbent dosage (5–8 g/L), temperature (T = 298 K), and adsorption equilibrium time (t = 180 min). The removal percentage of uranium(VI) decreases with increasing initial concentration of uranium(VI). The Langmuir isotherm model, which suggests predominant monolayered sorption, is better than Freundlich and Temkin models to elucidate the adsorption isotherm of adsorbed uranium. Kinetic analyses indicate that the uranium(VI) adsorption of the modified rice stem is mainly controlled by surface adsorption. The pseudo-second-order kinetic model, with the correlation coefficient of R2 = 0.9992, fits the adsorption process much better than other kinetic models (e.g., pseudo-second-order kinetic model, Elovich kinetic model, and intraparticle diffusion model). The thermodynamic parameters ΔG0, ΔH0, and ΔS0 demonstrate that the adsorption of uranium(VI) is an endothermic and spontaneous process, which can be promoted by temperature. The adsorption of uranium can change the morphology and the structure characteristics of the modified rice stem through interaction with the adsorption sites, such as O-H, C=O, Si=O, and P-O on the surface.

Critical Rare Earth Element Recovery from Coal Ash Using Microsphere Flower Carbon

“…In acidic solution, thorium can have different charge as at pH < 3 Th 4+ ions exist, then at pH 3–4 Th­(OH) 3+ / Th­(OH) 2 2+ ions, and at pH > 4 thorium can hydrolyze into polynuclear species . Uranium is unique, as it forms UO 2 2+ as the primary ion at pH < 3.2, then begins to form UO 2 (OH) 2 –H 2 O at higher pH . The extraction of rare earth ions at pH 4–5 has been previously reported to be the best pH for REE extraction .…”

“…35 Uranium is unique, as it forms UO 2 2+ as the primary ion at pH < 3.2, then begins to form UO 2 (OH) 2 − H 2 O at higher pH. 44 The extraction of rare earth ions at pH 4−5 has been previously reported to be the best pH for REE extraction. 2 These results indicate a potential for industrially pH-based ion separations of rare earth, thorium, and uranium elements.…”

An effective uranium removal using diversified synthesized cross-linked chitosan bis-aldehyde Schiff base derivatives from aqueous solutions

“…A comparison of q max values demonstrates that synthesized Cs-BFPA, Cs-BFB, and Cs-BODB exhibit a decent aptitude for uranium adsorption. The sorption capacity of CBASB derivatives (Cs-BFPA, Cs-BFB, and Cs-BODB) for uranium(VI) was significantly higher than those acquired from the literature in Table 3 (Oren et al 2000;Venkatesan et al 2004;Wang et al 2009;Kadous et al 2010;Morsy 2015;Orabi et al 2016Orabi et al , 2020Ali and Nouh 2019;Fouad et al 2019;Xiao-teng et al 2019;Orabi et al 2021). Also, as shown in Table 4, although the sorption capacity of CBASB derivatives resin is lower than some novel adsorbents, e.g., graphene oxide (Sun et al 2015), their regeneration has not been considered.…”

Box–Behnken design for removal of uranium(VI) from aqueous solution using poly(ethylene glycol) based dicationic ionic liquid impregnated chitosan

“…During the stages of nuclear fuel production such as mining, purification, and enrichment, large amount of uranium polluted wastewater is produced. Additional uranium sources are natural deposits and depleted uranium ammunitions [1]. Uranium exists mostly in the valence states of uranium(IV) and uranium(VI) depending on the environment.…”