Harnessing Renewable Enteromorpha: Development of a Magnetic Biochar Composite for Enhanced Cs+ Adsorption and Sustainable Wastewater Remediation

The presence of radioactive nuclides has garnered widespread attention, particularly cesium (Cs), which serves as a common radioactive element that enters water bodies through industrial wastewater, nuclear power plant discharges, and nuclear accidents, posing a serious threat to water source safety and the ecological environment. To effectively remove radioactive components from wastewater, the selection of appropriate adsorbents is crucial. Therefore, this study developed a thiourea-doped Prussian blue magnetic porous Enteromorpha biochar (PB/Fe3O4/MEC) for efficient cesium (Cs+) removal from radioactive wastewater. The adsorbent was synthesized through KOH assisted carbonization, thiourea doping, magnetic modification, and in-situ PB anchoring. PB/Fe3O4/MEC exhibited a high Cs+ adsorption capacity of 37.04 mg/g and a saturation magnetization of 17.93 emu/g, enabling rapid magnetic separation. The modified biochar exhibited a porous structure with increased specific surface area (371.49 m2/g) and abundant sulfur-containing functional groups. The adsorption mechanism of Cs+ by PB/Fe3O4/MEC composite involves a multi-pathway synergistic process, which mainly includes ion exchange and lattice trapping through the cubic lattice of PB, complexation reaction through the surface functional groups of biochar, mesoporous adsorption on the surface of biochar, and Lewis acid-base interaction. This work offers a sustainable strategy for algal biomass valorization and effective treatment of Cs+ contaminated water.