Enhancing volatile organic compounds (VOC) adsorption and electrothermal regeneration of CuBTC using carbonaceous and metallic modifiers

Abstract

This study aimed to enhance the adsorption capacity for volatile organic compounds (VOCs) and the electrical conductivity of a metal-organic framework (MOF) CuBTC to enable electrothermal regeneration after VOC exposure. CuBTC was modified by integrating carbonaceous materials using sonication-assisted synthesis, solvothermal techniques, and post-synthesis physical mixing, as well as incorporating metallic modifiers using sonication-assisted synthesis. X-ray diffraction (XRD) confirmed the samples' structural integrity, and thermogravimetric analysis (TGA) provided insights into thermal stability up to 250 °C and modifier content in the final product. Nitrogen and n-heptane adsorption isotherms assessed adsorption properties and surface characteristics, while transmission electron microscopy (TEM) evaluated the dispersion of the modifiers. Electrical resistivity measurements indicated that graphene was the most effective in reducing resistivity (achieving resistivity of 0.04 Ω m), followed by CNT-modified samples. Although most modified samples had reduced surface areas and porosities, physically mixing CuBTC with 50 wt% PC (porous carbon) yielded a sample with a surface area of 1294 m²/g, surpassing the 1228 m²/g of unmodified CuBTC, with a resistivity of 0.42 Ω m, within the suitable range for electrothermal regeneration (0.2–0.8 Ω m). The electrothermal regeneration of this sample consumed 71 kJ/g.hr, less than the 300 kJ/g.hr required for conventional regeneration, and reached a desorption temperature of 120 °C in 30 min, compared to 60 min for conventional regeneration. This proof-of-concept study demonstrates the potential for modifying CuBTC to produce electrically conductive MOFs suitable for electrothermal regeneration. It offers an energy-efficient approach to pollution control and remediation.