Ecofriendly, selective removal of radioactive strontium ions in aqueous solutions using magnetic banana peels

Radionuclide Sr²⁺ in aqueous solution was removed using a large amount of banana peel (BP). Magnetized BP, mag@BP, was synthesized for recovery after the adsorption process. The synthesis was a very simple process of precipitation of BP with a magnetic substance. The synthesized adsorbent was thoroughly examined by performing Fourier-transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction analysis, and vibration sample magnetometer analysis. Moreover, mag@BP has a Sr²⁺ maximum adsorption capacity of 23.827 mg/g according to isothermal adsorption, which is the best fit for the Langmuir isotherm model. In the pH effect experiment, the highest Sr²⁺ adsorption capacity was found at pH 9, and it has a spontaneous adsorption mechanism through experiments on temperature, time, and selectivity, and it reaches adsorption equilibrium within a short time and has high selectivity through competitive adsorption with Na⁺. In addition, an adsorption mechanism accompanied by ion exchange with K⁺ on the surface of BP, bonding with various functional groups, and electrical attraction were established. Therefore, mag@BP is suitable for use an environmentally friendly, low cost, and recoverable adsorbent for magnetic removal of Sr²⁺ from aqueous solutions. Further, unlike other carbon-based adsorbents, it does not cause cytotoxicity.