Removal of Sr(II) in Aqueous Solutions Using Magnetic Crayfish Shell Biochar

The cooling water of nuclear power plants and discarded crayfish shells (CS), both containing Sr(II), are waste resources that cause environmental pollution and endanger human health. In this study, magnetic biochar produced by crayfish shells (mag@CSBC) was used as an adsorbent to remove radionuclide Sr(II) in an aqueous solution and under irradiation conditions. Scanning electron microscopy, X-ray diffraction analysis, Fourier-transform infrared spectroscopy and vibration sample magnetometer analysis were used to characterize mag@CSBC. In addition, an isothermal adsorption experiment conducted under irradiation conditions determined that the maximum adsorption capacity of mag@CSBC was 21.902 mg/g, which was 1.896 mg/g higher than that from experiments conducted under conditions without irradiation and more suitable for the Freundlich isotherm model. The kinetic experiment proved that irradiation could improve the adsorption cap acity of mag@CSBC and reduce the adsorption equilibrium time. At the same time, the experiment further proved that, under irradiated conditions, the adsorption rate of mag@CSBC can reach more than 90%, and the adsorption capacity is the highest when the pH is 8 and the reaction process is exothermic. Competitive adsorption with Na(I) has a high selectivity and strong recyclability. Finally, the mechanism of Sr(II) adsorption by mag@CSBC under irradiation was studied. In conclusion, mag@CSBC, as a low-cost, easy-to-synthesize, environmentally friendly and easy-to-recycle adsorbent, can be applied in batches for the removal of Sr(II) in aqueous solutions. In particular, the concept of using irradiation technology to optimize adsorption behavior serves as an inspiration for future research.