Sub-theme
4. Supporting Aquatic Ecosystem Health and Functions
Topic
4-8. Water quality improvement
Body
Cr(VI) is one of the most toxic heavy metals in aquatic systems, which is seriously destructive to life and the environment and can persist for decades after the source of pollution has ceased, therefore, it is crucial to study the complex phenomenon of controlling the transfer of Cr(VI) in the environment and to develop new removal techniques. In this regard, the synthesis of materials that can absorb Cr(VI) directly from water systems without causing secondary pollution is a research direction with great potential. In this study, Fe3O4 nanoparticles were prepared by chemical precipitation method, and amorphous SiO2 shells were coated with superparamagnetic nanospheres using the modified Sol-Gel method and finally silica-coated Fe3O4 particles (MS) were prepared. The structural characteristics were analyzed by combining SEM, XRD and VSM characterization, and a series of simulated adsorption experiments were designed to investigate the effects of changes in solution environment (e.g. time, temperature, pH and coexisting ions) on the adsorption effect, and its ability to remove Cr(VI) from water was comprehensively evaluated. The experimental data showed that the adsorption of Cr(VI) on MS materials followed the Langmuir isotherm model and the kinetic adsorption was in accordance with the pseudo-secondary kinetic model. Under these conditions, the synthesized strong magnetic nanoscale materials exhibited extremely high removal rates (64.8%) for Cr(VI) adsorption in water, and the adsorption capacity of MS(13.6mg·g-1)was much higher than that of the Mobil Composition of Matter No.48 (4.0mg·g-1), coconut shell activated carbon (5.5mg·g-1) and bentonite (1.9mg·g-1), which are conventional nanoscale adsorption materials. The adsorption effect was the most obvious when the pH = 2 but the adsorption effect was not good under alkaline conditions. This study is not only a reference value for the study of wastewater remediation technology for the removal of Cr(VI) from water by new ecological nanomaterials, but also reveals the great prospect of removing heavy metal ions from wastewater by magnetic adsorption separation.