Optimized self-assembly of ZIF-8 on Haematococcus pluvialis for iodine adsorption

In recent years, the combination of biotemplates and metal – organic frameworks (MOFs) has been frequently applied in environmental remediation. In this study, ZIF-8 was successfully self-assembled on the surface of Haematococcus pluvialis (HP) under room-temperature, and the optimal solvent ratio for assembly was determined. The iodine adsorption performance was evaluated under different conditions, including ionic strength, pH, concentration, and contact time. The results indicated that HP@ZIF-8 with the best morphology and adsorption performance was obtained when the solvent ratio of methanol-to-ethanol was 25%. The optimal adsorption conditions for HP@ZIF-8 were found to be an ionic strength of 0.01 mol·L⁻¹ and pH = 5.5. Thermodynamic and kinetic model analyses indicated that the adsorption process was mainly governed by multilayer chemical adsorption. At 25°C, the adsorption capacity reached 1182 mg•g⁻¹ after 120 min, and the maximum adsorption capacity was 2050 mg•g⁻¹. This study highlights the critical role of solvent polarity in the synthesis of algae-MOF composite materials and provides valuable guidance for the future synthesis of such materials.