Pistachio shells as remediating agents for uranium in contaminated industrial seawater

Younes, Ali; Ali, Jafar Sunga; Nur, Mohamed Tousif; Duda, Artem; Wang, Jasmine; Samson, Jacopo; Kawamura, Akira; Francesconi, Lynn C.; Alexandratos, Spiro D.; Drain, Charles Michael

doi:10.1016/j.jenvrad.2020.106209

Cited by 14 publications

(7 citation statements)

References 40 publications

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“…The intraparticle models showed no linear correlation and a y-intercept C that was not close to 0, indicating that intraparticle pore diffusion is not the sole rate controlling step. 21,35 From our obtained results, a release of calcium ions was observed at low pH, 0.5 μmol/mg of HAP materials after contact with uranyl vs before, and appears to decrease as pH increases. This is explained by the high adsorption of the hydronium ion at low pH, and more prominently, the dissolution of the HAP material.…”

Section: ■ Discussionmentioning

confidence: 61%

“…This observation is in agreement with the suggested mechanism of uranyl complexation reported by Fuller et al, as discussed in the FT-IR Characterization section. The intraparticle models showed no linear correlation and a y -intercept C that was not close to 0, indicating that intraparticle pore diffusion is not the sole rate controlling step. , …”

Section: Discussionmentioning

confidence: 91%

“…The Freundlich isotherm describes multilayer adsorption sites for uranyl distributed among the heterogeneous HAP interface, and therefore, the findings are in agreement with HAP's classification as a Type III isotherm, which adsorbs via an unrestricted multilayer formation process. 23 The n values of 0.998 for TRIS/NaCl and 1.0049 for PBS can indicate that the adsorption is directly proportional to pressure and that, upon increased loading and increased concentration, the relative adsorption by the biomass decreases, 21 a behavior shown by Figure 3. In general, it appears that TRIS buffer does not compete with uranyl uptake, while PBS buffer provides a competitor to uranyl for uptake.…”

Section: ■ Discussionmentioning

confidence: 99%

“…Sum squared deviations were calculated by taking the difference between model and experimental y -values for both pseudo-first-order and pseudo-second-order and then squaring the resulting difference. This allowed for comparison between the two kinetic models and for determination of which kinetic model best fit the experimental data …”

Section: Methodsmentioning

confidence: 99%

“…This allowed for comparison between the two kinetic models and for determination of which kinetic model best fit the experimental data. 21 Intraparticle diffusion was used to investigate whether pore or film diffusion was the rate controlling step of adsorption. The equation for intraparticle diffusion is defined as…”

Section: +mentioning

confidence: 99%

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Uptake and Removal of Uranium by and from Human Teeth

Younes

Ali

Duda

et al. 2021

Chem. Res. Toxicol.

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Uranium-238 ( 238 U), a long-lived radiometal, is widespread in the environment because of both naturally occurring processes and anthropogenic processes. The ingestion or inhalation of large amounts of U is a major threat to humans, and its toxicity is considered mostly chemical rather than radiological. Therefore, a way to remove uranium ingested by humans from uraniumcontaminated water or from the air is critically needed. This study investigated the uranium uptake by hydroxyapatite (HAP), a compound found in human bone and teeth. The uptake of U by teeth is a result of U transport as dissolved uranyl (UO 2 2+) in contaminated water, and U adsorption has been linked to delays in both tooth eruption and development. In this present work, the influence of pH, contact time, initial U concentration, and buffer solution on the uptake and removal of U in synthetic HAP was investigated and modeled. The influence of pH (pH of human saliva, 6.7−7.4) on the uptake of uranyl was negligible. Furthermore, the kinetics were extremely fast; in one second of exposure, 98% of uranyl was uptaken by HAP. The uptake followed pseudosecond-order kinetics and a Freundlich isotherm model. A 0.2 M sodium carbonate solution removed all the uranyl from HAP after 1 h. Another series of in vitro tests were performed with real teeth as targets. We found that, for a 50 mg/L U in PBS solution adjusted to physiological pH, ∼35% of the uranyl was uptaken by the tooth after 1 h, following pseudo-first-order kinetics. Among several washing solutions tested, a commercially available carbonate, as well as a commercially available fluoride solution, enabled removal of all the uranyl taken up by the teeth.

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Section: ■ Discussionmentioning

confidence: 61%

Section: Discussionmentioning

confidence: 91%