Dynamic benzene adsorption performance of microporous TMA+-exchanged montmorillonite: The role of TMA+ cations

Tetramethylammonium (TMA+) exchanged montmorillonites (TMA-Mts) of various surfactant (TMA+) dosages were prepared, and the roles of TMA+ cations in the microstructure and dynamic benzene adsorption performance of TMA-Mts were investigated. TMA+ cations were intercalated into the interlayer space of montmorillonite (Mt), and they exhibited dual effects on the benzene adsorption by TMA-Mts. For one thing, the intercalated TMA+ cations arranged loosely, creating an interlayer microporous structure. The interlayer micropores were important benzene adsorption sites, and the dynamic benzene adsorption capacity (q value) positively correlated to the microporous surface area (Smicro). The optimized dosage of TMA+ was 1.5 times the cation exchange capacity of Mt itself, which resulted in a TMA-Mt with the largest Smicro and q values of 65.0 m2/g and 425.3 mg/g, respectively. On the other hand, the intercalated TMA+ cations could interact with benzene molecules, further increasing the benzene adsorption performance of TMA-Mt but decreasing the diffusion and mass transfer of benzene molecules through TMA-Mt. In addition, TMA-Mt displayed remarkable regenerability, with a recycling efficiency exceeding 90%. These results indicated that modifying montmorillonite with small quaternary ammonium cation is an effective strategy to enhance the adsorption of volatile organic compounds (VOCs) by Mt and the TMA-Mts are promising adsorbents for VOCs remediation.