Demystifying the interfacial aquatic geochemistry of thallium(I): New and old data reveal just a regular cation

Coup, K; Swedlund, Peter J.

doi:10.1016/j.chemgeo.2015.02.003

Cited by 40 publications

(19 citation statements)

References 16 publications

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“…In the solution with a pH value higher than the PZC, the adsorption capacity of iron oxides/hydroxides increases as it can favor the electrostatic attraction between them and Tl(I) ions. This is consistent with the adsorption behavior of Tl(I) on ferrihydrite which is only appreciable at alkaline pH [40]. Since Tl(I) is converted to TlOH (aq) at high pH (11.7), as suggested by Lin and Nriagu [25], an excessive pH, i.e., intensified converting, will reduce the adsorption efficiency of Tl species.…”

Section: Effect Of Initial Phsupporting

confidence: 87%

“…The EC removal of Tl(I) from wastewater, especially that with low Tl(I) concentration, has been rarely studied. Besides, the Tl(I) sorption is appreciable at alkaline pH [40]. To evaluate EC treatment effects, a series of experiments were performed to treat low Tl(I) samples with a comparatively broader initial pH range of 7-12.…”

Section: Effect Of Initial Phmentioning

confidence: 99%

“…Metal oxides/hydroxides generated in the EC process have much higher adsorption capacity than the pre-synthetized ones, which guaranteed the removal efficiency [28], especially in the treatment of heavy metals [33,34,39]. Although the affinity of Tl(I) cation to iron oxides/hydroxides is usually expected to be weak because it has low logK MOH of 10 −13.2 , study [40] shows that Tl(I) can adsorb well on ferrihydrite in alkaline solutions (pH > 8). Therefore, besides the eight potential feasible technology schemes for different Tl industry wastewater recommended by Xu et al [7], EC may be another feasible solution for low Tl concentration industrial wastewater treatment.…”

Section: Introductionmentioning

confidence: 99%

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Removal of Trace Thallium from Industrial Wastewater by Fe0-Electrocoagulation

Yang

et al. 2020

Water

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As thallium (Tl) is a highly toxic heavy metal, there are compulsory environmental regulations in many countries on minimizing its release. This research investigated the treatment of real industrial wastewater with low Tl(I) concentration by Fe0-electrocoagulation (Fe0-EC) in a batch aeration-forced pump cycle reactor. The effects of pH (7–12), current density (8.3–33.3 mA/cm2), dissolved oxygen (DO) in wastewater, and initial Tl(I) concentration (66–165 µg/L) on Tl(I) removal efficiency were investigated. The removal efficiency of Tl(I) is pH-dependent, to be exact, it increases significantly with pH rising from 8 to 11. Initial pH of influent and DO concentration were the key operation parameters which strongly affect Tl(I) removal. After the water sample with initial Tl(I) concentration of 115 µg/L was treated for 12 min by a single-step process at pH of 11 and current density of 16.7 mA/cm2, the residual Tl(I) concentration was decreased to beneath the emission limit in China (2 µg/L) with a low energy consumption of 0.82 kWh/m3. By prolonging the operation time, the concentration was further reduced to 0.5 µg/L or even lower. The main composition of the flocculent sludges is iron oxyhydroxide, yet its crystal structure varies dependent on pH value which may result in different Tl(I) removal efficiency. Feroxyhyte nanosheets generate in situ by Fe0-EC, which contributes to the rapid and effective removal of Tl(I), while the speedy oxidation under DO-enriched conditions benefits the feroxyhyte formation. The mechanism of Tl(I) removal by Fe0-EC is attributed to the combination of electrostatic attraction and the formation of inner-sphere complexes. As shown in the technical and mechanical studies, Fe0-EC technology is an effective method for low Tl concentration removal from wastewater.

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Section: Effect Of Initial Phsupporting

confidence: 87%

Section: Effect Of Initial Phmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Removal of Trace Thallium from Industrial Wastewater by Fe0-Electrocoagulation

Yang

et al. 2020

Water

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“…Few studies have addressed Tl(I) sorption processes, mostly on manganese oxides and iron oxihydroxides (Bidoglio et al, 1993;Lin and Nriagu, 1998;Casiot et al, 2011;Peacock and Moon, 2012;Coup and Swedlund, 2015) so far. Nevertheless, Peacock and Moon (2012) identified two types of interaction depending on the bearing phases.…”

Section: Comparison To Other Bearing Phasesmentioning

confidence: 99%

Thallium (Tl) sorption onto illite and smectite: Implications for Tl mobility in the environment

Martin

Wissocq

Benedetti

et al. 2018

Geochimica et Cosmochimica Acta

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Clay minerals play a relevant role in the transport and fate of trace elements in the environment. Though illite has been referred as an important Thallium (Tl) bearing phase in soils, mechanisms and affinity of thallium for clay minerals remain poorly known. This study investigated the sorption behavior of thallium as Tl(I) onto illite and smectite, two clay minerals occurring mainly in soils and sediments. Different sorption experiments were carried out under various pH conditions and Tl concentrations, in competition with sodium and calcium at a constant ionic strength of 0.01 mol L À1. Our results showed that illite displayed more affinity than smectite for thallium. With illite, the distribution coefficients (K d in L kg À1) varied between 10 2.75 ± 0.17 and 10 4.0 ± 0.17 in Na solutions versus between 10 2.25 ± 0.17 and 10 3.0 ± 0.17 in Ca solutions, depending on pH. With smectite, K d (in L kg À1) ranged between 10 2.50 ± 0.16 and 10 3.20 ± 0.16 and between 10 1.25 ± 0.16 and 10 1.95 ± 0.16 in Na and Ca solutions, respectively. Sorption behavior was described with the Multi-Site Ion Exchanger model and selectivity coefficients with respect to protons were calculated for the first time. In all cases, independently of clay mineral and background electrolyte, low capacity but highly reactive sites were dominant in thallium uptake, highlighting Tl affinity for those sites. Moreover, the exchangeable and reversible interactions between Tl + and clays reactive sites suggested that in changing conditions, thallium could be released in solution. The role of clay minerals in thallium environmental cycle is evident and confirmed illite to be a dominant Tl bearing phase, in some environment competing with manganese oxides. Compared to others Tl bearing mineral phases, clays are ranked as follows: MnO 2 > illite > smectite $ ferrihydrite ! Al 2 O 3 $ goethite > SiO 2. Finally, over the three monovalent cations (Tl, Rb, Cs) Tl is the one less sorbed on illite independently of the background cations.

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“…Besides surface protonation/deprotonation reactions, hydrolysis reactions may also control the behavior of trace elements. Hydrolysis is, likewise, pH‐dependent (e.g., Coup & Swedlund, 2015). For example, the hydrolysis of Cd at pH > 9 can change the Cd species from Cd 2+ to Cd(OH) 2 0 , and the latter can easily form inner‐sphere complexes on clay surfaces and thus increase the adsorption of Cd on clays (Hao et al., 2020).…”

Section: Discussionmentioning

confidence: 99%