Adsorption of Sr(II) cations onto phosphated mesoporous titanium dioxide: Mechanism, isotherm and kinetics studies

In this work, phosphate-modified titanium dioxide nanoparticles with mesoporous structure were synthesized and utilised as an efficient nanoadsorbent for Sr(II) removal from aqueous environment. The globular titania particles with a 3–4 nm diameter with chemosorbed on their surfaces phosphate groups = Ti(O2POOH) have been obtained by liquid-phase synthesis. The characterization of titania nanoparticles were performed using XRD, TEM, IR-spectroscopy and Brunauer-Emmett-Teller analyses. The synthesized modified adsorbents exhibited SBET = 396–410 m2 g−1 and mesopore volume of 0.262 – 0.275сm3 g−1. The isotherm and kinetic models were used for the description of Sr(II) adsorption. The sample 4P-TiO2 showed the best adsorption ability for strontium ions removal. The adsorption capacity of Sr(II) onto modified 2P-TiO2, 4P-TiO2 and 8P-TiO2 samples was found to be 94.1, 172.5, 128.9 mg/g, respectively. An adsorption mechanism for Sr(II) removal was proposed. The adsorption/desorption studies were conducted to find the reusability of phosphated adsorbents. A titanium dioxide-based mesoporous material possesses a significant adsorption activity due to high content of surface acid sites. All the outcomes revealed that the phosphate modified titania showed great potential in Sr(II) removal from aqueous environment and nuclear effluents.