# Inverse Gas Chromatography for Characterization of Adsorption Ability of Carbon–Mineral Composites for Removal of Antibiotics from Water

## TL;DR

This study uses inverse gas chromatography to show that surface properties of carbon-mineral composites are more important than structural ones for removing antibiotics from water.

## Contribution

The study demonstrates that surface energetic and acid-base properties, not bulk structure, correlate with antibiotic removal efficiency.

## Key findings

- No clear correlation exists between bulk structural characteristics and antibiotic removal efficiency.
- Antibiotic removal is correlated with the dispersive component of surface free energy and the Ka/Kb ratio.
- Surface energetic parameters and acid-base properties are more important for adsorption than structural characteristics.

## Abstract

In this study, inverse gas chromatography (IGC) was applied to characterize the key surface physicochemical properties of carbon–mineral composites and to clarify how these properties relate to removal efficiencies of selected antibiotics, with particular emphasis on surface energetic and acid–base characteristics rather than bulk structural parameters. The dispersive component of surface free energy and the acid–base characteristics (Ka/Kb ratio) were determined, alongside measurements of carbon content, while specific surface areas were compared with data reported previously. We found that there is no clear correlation between bulk structural characteristics and the removal efficiency of ciprofloxacin, doxycycline, sulfamethoxazole, and tetracycline. In contrast, the removal of all investigated antibiotics was found to be correlated with the dispersive component of surface free energy and the Ka/Kb ratio. The results suggest that surface energetic parameters and acid–base properties are more closely associated with antibiotic adsorption behavior than basic structural characteristics alone. These findings demonstrate that IGC provides valuable insight into adsorption processes and highlight the importance of surface physicochemical properties for interpreting and predicting the adsorption properties of carbon–mineral composites.