In 2015, the U.S. Government Accountability Office reported that the Bureau of Land Management had identified at least 7013 contaminated and potentially contaminated federal sites. The sites may pose a risk to human health or the environment. The estimated total liability for environmental cleanup was over $350 billion for the identified areas. Although many cleaning and remediation methodologies exist, nanotechnology using carbonaceous materials presents significant advantages concerning efficiency and performance. One of such nanomaterials is carbon nano-onions (CNOs). CNOs consist of a hollow spherical fullerene core surrounded by larger concentric fullerene layers forming quasi-spherical multilayers. Pristine CNOs are insoluble in polar and nonpolar solvents. Thus their study is only possible after surface functionalization. In the project herein, CNOs were utilized in the removal of organic molecules from aqueous solutions. To this end, CNOs were synthesized by arc discharge underwater, and magnetite nanoparticles were incorporated into its surface, leading to a composite having magnetic properties. The study of the applicability of mag-CNOs for environmental remediation consisted of removing known compounds from a water sample. In the experiment, dyes blue #1, yellow#4, and red #40 were used as the targets for removal. The adsorption isotherms were investigated for different magnetite-CNOs composites. The experiments consisted of mixing the magnetite-CNOs composites with the target molecules (known concentration’s solution) for 48 hours. After the adsorption time, the concentration of the target was determined via UV-visible spectroscopy. The study results showed differential absorption capacities for pristine and magnetized-CNOs materials, and the results were contrasted against commonly used carbon substrates (i.e., activated carbon). The experiment shows the potential for the CNOs’ usage in the adsorption removal of organic molecules from water samples. Findings from the study contribute to the existing body of knowledge on environmental remediation of anthropogenic chemicals in the water supply, particularly of chemicals with known bioaccumulation potential.

Thermodynamic studies of dyes’ adsorption of magnetite-carbon nano-onions composites for environmental remediation applications

ACS Spring 2022

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