Adsorption mechanisms of thallium(I) and thallium(III) by titanate nanotubes: Ion-exchange and co-precipitation

JOURNAL OF COLLOID AND INTERFACE SCIENCE

卷:423

Article

Liu, Wen^1,2  Zhang, Pan³  Borthwick, Alistair G. L.⁴  Chen, Hao³  Ni, Jinren^1,2 

[1] Peking Univ, Shenzhen Grad Sch, Sch Environm & Energy, Shenzhen Key Lab Heavy Met Pollut Control & Reuti, Shenzhen 518055, Peoples R China

[2] Peking Univ, Dept Environm Engn, Key Lab Water & Sediment Sci, Minist Educ, Beijing 100871, Peoples R China

[3] China Agr Univ, Coll Resources & Environm Sci, Beijing 100193, Peoples R China

[4] Univ Edinburgh, Sch Engn, Inst Energy Syst, Edinburgh EH9 3JL, Midlothian, Scotland

关键词: Thallium;    Titanate nanotubes;    Adsorption;    Ion-exchange;    Co-precipitation;   

DOI  :  10.1016/j.jcis.2014.02.030

来源: Elsevier

【 摘 要 】

Hydrothermally-synthesized titanate nanotubes (TNTs) are found to be excellent at adsorption of highly toxic thallium ions. Uptake of both thallium ions is very fast in the first 10 min. The adsorption isotherm of Tl(I) follows the Langmuir model with maximum adsorption capacity of 709.2 mg g(-1). Ion-exchange between Tl+ and Na+ in the interlayers of TNTs is the primary mechanism for Tl(1) adsorption. Excess Tl+ undergoes further exchange with W. The adsorption mechanism is different for Tl(III), and involves either ion-exchange with Na+ at low Tl(III) concentration or co-precipitation in the form of Tl(OH)(3) with TNTs at high Tl(III) concentration. XPS analysis indicates that the ion-exchange process does not change the basic skeleton [TiO6] of TNTs, whereas Tl(OH)(3) precipitation increases the percentage composition of O within the surface hydroxyl groups. XRD analysis also confirms the formation of Tl(OH)(3) on TNTs at high initial concentration of TI(III). Coexisting Ne and Ca2+ hardly inhibit adsorption, indicating good selectivity for thallium by TNTs. Furthermore, TNTs can be reused efficiently after HNO3 desorption and NaOH regeneration, making TNTs a promising material to remove thallium from wastewaters. This study also confirms that co-precipitation is another important adsorption mechanism for easily hydrolytic metals by TNTs. (C) 2014 Elsevier Inc. All rights reserved.

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