Solubility of C60 in solvent mixtures

Area of Science:

• Environmental Science
• Materials Science
• Chemistry

Background:

• Fullerene C60 (a carbon allotrope) is increasingly used in consumer products, raising concerns about occupational, public, and environmental exposure.
• Understanding fullerene C60's behavior in industrial solvents is crucial for assessing its environmental risk and fate, as solvate formation can alter its properties.

Purpose of the Study:

• To investigate fullerene C60 solvate formation in common industrial solvents by measuring its solubility.
• To provide data for risk assessment and understanding the environmental persistence of fullerene C60.

Main Methods:

• Solubility measurements of fullerene C60 were conducted in pure solvents: toluene, tetrahydrofuran, ethanol, and acetonitrile.
• Solubility was also measured in binary solvent mixtures: toluene-acetonitrile, toluene-ethanol, toluene-tetrahydrofuran, and acetonitrile-tetrahydrofuran.
• The solubility data were modeled using Wohl's equation to analyze solvate formation.

Main Results:

• Fullerene C60 exhibited varying solubilities: 3000 mg/L in toluene, 11 mg/L in tetrahydrofuran, 1.4 mg/L in ethanol, and 0.04 mg/L in acetonitrile.
• Solubility data in mixed solvent systems provided insights into solvate formation.
• Wohl's equation modeled the solubility data with reasonable accuracy.

Conclusions:

• The crystal energy term for fullerene C60 in tetrahydrofuran differed significantly from other solvents.
• This suggests that the solid phase of fullerene C60 in equilibrium with tetrahydrofuran solution may be a solvated crystal.
• Understanding these solvates is key to predicting fullerene C60's environmental impact.