Strontium ion (Sr2+) separation from seawater by hydrothermally structured titanate nanotubes: Removal vs. recovery

Jungho Ryu; Soonhyun Kim; Hye Jin Hong; Jeongsik Hong; Minsun Kim; Taegong Ryu; In Su Park; Kang Sup Chung; Jum Suk Jang; Byoung Gyu Kim

doi:10.1016/j.cej.2016.06.131

Strontium ion (Sr²⁺) separation from seawater by hydrothermally structured titanate nanotubes: Removal vs. recovery

Jungho Ryu, Soonhyun Kim, Hye Jin Hong, Jeongsik Hong, Minsun Kim, Taegong Ryu, In Su Park, Kang Sup Chung, Jum Suk Jang, Byoung Gyu Kim

Division of Energy Techonology

Research output: Contribution to journal › Article › peer-review

92 Scopus citations

Abstract

Strontium ion (Sr²⁺) separation from seawater has attracted attention for radioactive pollutants removal and for Sr²⁺ recovery. Herein, we synthesized titanate nanotubes (TiNTs) via a simple hydrothermal reaction, characterized their physicochemical properties, and systematically evaluated Sr²⁺ sorption behavior under various reaction conditions corresponding to seawater environments. The synthesized TiNTs exhibited a fibril-type nanotube structure with a high specific surface area (260 m²/g). Sr²⁺ adsorption on TiNTs rapidly occurred following a pseudo-second-order kinetic model and was in good agreement with the Langmuir isotherm model, indicating a maximum adsorption capacity of 97 mg/g. Based on the Sr²⁺ uptake and Na⁺ release with a stoichiometric balance, the Sr²⁺ sorption mechanism on TiNTs was ion exchange between Na⁺ in the TiNT lattice and Sr²⁺ in the solution phase, as confirmed by XRD and Raman analysis. Among the competitive ions, Ca²⁺ significantly hindered Sr²⁺ sorption on TiNTs, whereas Na⁺ only slightly affected Sr²⁺ sorption, despite the Na⁺ exchange sorption mechanism. The effect of Ca²⁺ on Sr²⁺ sorption was evaluated by introducing a distribution coefficient (K_d) as a critical factor in determining the selectivity, which revealed a slightly higher selectivity for Sr²⁺. The Sr²⁺ adsorption-desorption test in a real seawater medium enabled the determination of K_d and the concentration factor (CF) for co-existing matrix ions in seawater; these values were evaluated for Sr²⁺ removal and recovery from seawater. TiNTs were regenerated by acid treatment and reused through consecutive adsorption-desorption experiments. While most studies addressing Sr²⁺ sorption using TiNTs aimed for extraction from wastewater and radioactive wastewater, this study elucidated Sr²⁺ sorption behavior under seawater conditions and provided insights into developing the removal and recovery processes from seawater.

Original language	English
Pages (from-to)	503-510
Number of pages	8
Journal	Chemical Engineering Journal
Volume	304
DOIs	https://doi.org/10.1016/j.cej.2016.06.131
State	Published - 15 Nov 2016

Bibliographical note

Publisher Copyright:
© 2016

Keywords

Recovery
Seawater
Separation
Strontium
Titanate nanotubes

Access to Document

10.1016/j.cej.2016.06.131

Cite this

@article{a054075665dd4ee8b29a463c49446bb9,

title = "Strontium ion (Sr2+) separation from seawater by hydrothermally structured titanate nanotubes: Removal vs. recovery",

abstract = "Strontium ion (Sr2+) separation from seawater has attracted attention for radioactive pollutants removal and for Sr2+ recovery. Herein, we synthesized titanate nanotubes (TiNTs) via a simple hydrothermal reaction, characterized their physicochemical properties, and systematically evaluated Sr2+ sorption behavior under various reaction conditions corresponding to seawater environments. The synthesized TiNTs exhibited a fibril-type nanotube structure with a high specific surface area (260 m2/g). Sr2+ adsorption on TiNTs rapidly occurred following a pseudo-second-order kinetic model and was in good agreement with the Langmuir isotherm model, indicating a maximum adsorption capacity of 97 mg/g. Based on the Sr2+ uptake and Na+ release with a stoichiometric balance, the Sr2+ sorption mechanism on TiNTs was ion exchange between Na+ in the TiNT lattice and Sr2+ in the solution phase, as confirmed by XRD and Raman analysis. Among the competitive ions, Ca2+ significantly hindered Sr2+ sorption on TiNTs, whereas Na+ only slightly affected Sr2+ sorption, despite the Na+ exchange sorption mechanism. The effect of Ca2+ on Sr2+ sorption was evaluated by introducing a distribution coefficient (Kd) as a critical factor in determining the selectivity, which revealed a slightly higher selectivity for Sr2+. The Sr2+ adsorption-desorption test in a real seawater medium enabled the determination of Kd and the concentration factor (CF) for co-existing matrix ions in seawater; these values were evaluated for Sr2+ removal and recovery from seawater. TiNTs were regenerated by acid treatment and reused through consecutive adsorption-desorption experiments. While most studies addressing Sr2+ sorption using TiNTs aimed for extraction from wastewater and radioactive wastewater, this study elucidated Sr2+ sorption behavior under seawater conditions and provided insights into developing the removal and recovery processes from seawater.",

keywords = "Recovery, Seawater, Separation, Strontium, Titanate nanotubes",

author = "Jungho Ryu and Soonhyun Kim and Hong, {Hye Jin} and Jeongsik Hong and Minsun Kim and Taegong Ryu and Park, {In Su} and Chung, {Kang Sup} and Jang, {Jum Suk} and Kim, {Byoung Gyu}",

note = "Publisher Copyright: {\textcopyright} 2016",

year = "2016",

month = nov,

day = "15",

doi = "10.1016/j.cej.2016.06.131",

language = "English",

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journal = "Chemical Engineering Journal",

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TY - JOUR

T1 - Strontium ion (Sr2+) separation from seawater by hydrothermally structured titanate nanotubes

T2 - Removal vs. recovery

AU - Ryu, Jungho

AU - Kim, Soonhyun

AU - Hong, Hye Jin

AU - Hong, Jeongsik

AU - Kim, Minsun

AU - Ryu, Taegong

AU - Park, In Su

AU - Chung, Kang Sup

AU - Jang, Jum Suk

AU - Kim, Byoung Gyu

PY - 2016/11/15

Y1 - 2016/11/15

N2 - Strontium ion (Sr2+) separation from seawater has attracted attention for radioactive pollutants removal and for Sr2+ recovery. Herein, we synthesized titanate nanotubes (TiNTs) via a simple hydrothermal reaction, characterized their physicochemical properties, and systematically evaluated Sr2+ sorption behavior under various reaction conditions corresponding to seawater environments. The synthesized TiNTs exhibited a fibril-type nanotube structure with a high specific surface area (260 m2/g). Sr2+ adsorption on TiNTs rapidly occurred following a pseudo-second-order kinetic model and was in good agreement with the Langmuir isotherm model, indicating a maximum adsorption capacity of 97 mg/g. Based on the Sr2+ uptake and Na+ release with a stoichiometric balance, the Sr2+ sorption mechanism on TiNTs was ion exchange between Na+ in the TiNT lattice and Sr2+ in the solution phase, as confirmed by XRD and Raman analysis. Among the competitive ions, Ca2+ significantly hindered Sr2+ sorption on TiNTs, whereas Na+ only slightly affected Sr2+ sorption, despite the Na+ exchange sorption mechanism. The effect of Ca2+ on Sr2+ sorption was evaluated by introducing a distribution coefficient (Kd) as a critical factor in determining the selectivity, which revealed a slightly higher selectivity for Sr2+. The Sr2+ adsorption-desorption test in a real seawater medium enabled the determination of Kd and the concentration factor (CF) for co-existing matrix ions in seawater; these values were evaluated for Sr2+ removal and recovery from seawater. TiNTs were regenerated by acid treatment and reused through consecutive adsorption-desorption experiments. While most studies addressing Sr2+ sorption using TiNTs aimed for extraction from wastewater and radioactive wastewater, this study elucidated Sr2+ sorption behavior under seawater conditions and provided insights into developing the removal and recovery processes from seawater.

AB - Strontium ion (Sr2+) separation from seawater has attracted attention for radioactive pollutants removal and for Sr2+ recovery. Herein, we synthesized titanate nanotubes (TiNTs) via a simple hydrothermal reaction, characterized their physicochemical properties, and systematically evaluated Sr2+ sorption behavior under various reaction conditions corresponding to seawater environments. The synthesized TiNTs exhibited a fibril-type nanotube structure with a high specific surface area (260 m2/g). Sr2+ adsorption on TiNTs rapidly occurred following a pseudo-second-order kinetic model and was in good agreement with the Langmuir isotherm model, indicating a maximum adsorption capacity of 97 mg/g. Based on the Sr2+ uptake and Na+ release with a stoichiometric balance, the Sr2+ sorption mechanism on TiNTs was ion exchange between Na+ in the TiNT lattice and Sr2+ in the solution phase, as confirmed by XRD and Raman analysis. Among the competitive ions, Ca2+ significantly hindered Sr2+ sorption on TiNTs, whereas Na+ only slightly affected Sr2+ sorption, despite the Na+ exchange sorption mechanism. The effect of Ca2+ on Sr2+ sorption was evaluated by introducing a distribution coefficient (Kd) as a critical factor in determining the selectivity, which revealed a slightly higher selectivity for Sr2+. The Sr2+ adsorption-desorption test in a real seawater medium enabled the determination of Kd and the concentration factor (CF) for co-existing matrix ions in seawater; these values were evaluated for Sr2+ removal and recovery from seawater. TiNTs were regenerated by acid treatment and reused through consecutive adsorption-desorption experiments. While most studies addressing Sr2+ sorption using TiNTs aimed for extraction from wastewater and radioactive wastewater, this study elucidated Sr2+ sorption behavior under seawater conditions and provided insights into developing the removal and recovery processes from seawater.

KW - Recovery

KW - Seawater

KW - Separation

KW - Strontium

KW - Titanate nanotubes

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