Recyclable sodium titanate/graphite oxide/polyurethane polymer for efficient removal of radioactive strontium(ii) from contaminated water†

A novel ternary polymer of sodium titanate/graphite oxide/polyurethane (sodium titanate/GO/PUP) was synthesized in this work as an adsorbent for eliminating radioactive strontium from wastewater. Multiple techniques, such as XRD, FT-IR, SEM, TEM, BET and XPS, were used to characterize its morphology and physicochemical properties. Kinetic experimental data on Sr²⁺ fitted better with the pseudo-second-order model, with an adsorption rate of 99.4%, and the adsorption isotherm followed the Langmuir isotherm model, with a maximum adsorption capacity of 104.71 mg g⁻¹. The adsorbed Sr²⁺ ions were trapped permanently in the composite. The possible mechanism for Sr²⁺ removal was found to be ion exchange, with an unexpected mole ratio of nearly 1 : 1 between absorbed Sr²⁺ and exchanged Na⁺. Both pH and temperature were found to influence the adsorption process. Further, the results of phytotoxicity assessment indicated that sodium titanate/GO/PUP had no obvious biotoxicity, and the toxicity of Sr²⁺ wastewater was significantly reduced after treatment. Therefore, sodium titanate/GO/PUP is a safe and effective adsorbent for radioactive wastewater treatment and environmental remediation.