Superior adsorption of thallium(I) on titanium peroxide: Performance and mechanism

- Titanium peroxide was facilely synthesized via oxidation and precipitation method.
- Titanium peroxide was very effective for Tl(I) sorption.
- Titanium peroxide had high selectivity of sorption towards Tl(I).
- Tl(I) formed inner-surface complex on the surface of titanium peroxide.
- Titanium peroxide is a promising sorbent for thallium removal.

Thallium is a highly toxic pollutant to mammals and its removal from water is increasingly gaining attention. In order to effectively remove thallium(I), a much more mobile and difficult to be removed thallium species, nanostructured titanium peroxide was facilely synthesized via an oxidation coupled with precipitation process in this study. The morphology and surface properties of the titanium peroxide were analyzed by TEM, XRD, BET, FTIR and XPS techniques. The obtained amorphous peroxide consists of nanoparticles, with a surface area of 13.6 m2/g. The adsorption of Tl(I) is pH-dependent and increases with increasing pH-value. The titanium peroxide is very effective in removing Tl(I) from water, with a maximal adsorption capacity of 412 mg/g at pH 7.0. The present Ca2+, Mg2+, K+, Cu2+, Zn2+, fulvic acid and humic acid had no significant effect on Tl(I) adsorption, indicating the high adsorption selectivity of Tl(I) on titanium peroxide. Furthermore, Tl(I) uptake might be mainly achieved through ion-exchange reaction between Tl(I) ions and hydroxyl groups on the surface of the peroxide, resulting in the formation of inner-surface complex of Ti-O-Tl(I). The as-prepared titanium peroxide could be a promising alternate for thallium removal from water, due to its excellent Tl(I) removal performance, high selectivity and facile synthesis process.

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