Porous carbon derived from MOF-235 for the adsorption of methyl orange with high capacity

The increasing presence of synthetic dyes in wastewater poses a serious environmental threat, necessitating the development of efficient adsorbents for their removal. In this study, a highly porous carbonaceous adsorbent, Fe@C-350, was synthesized through direct carbonisation of MOF-235 under an argon atmosphere for efficient removal of methyl orange from wastewater. Compared to MOF-235, Fe@C-350 retains the inherent structure of MOF-235 while exhibiting a larger BET surface area and increased pore size. The use of Fe@C-350 as an adsorbent in methyl orange adsorption demonstrates exceptional adsorption capabilities over a broad pH range with a maximum adsorption capacity of 1666.7 mg·g⁻¹. The isotherm analyses indicate that the adsorption process is primarily determined by monolayer physical adsorption. The kinetic studies revealed a rapid adsorption rate, characterized by a high-rate constant of 0.025 g·mg⁻¹·min⁻¹. This can be attributed to the suitable pore size and abundant adsorption sites that facilitate the removal of methyl orange. Further investigation confirmed that Fe@C-350 retained over 98 % of its initial adsorption capacity after 10 regeneration cycles, thus confirming physical adsorption as the fundamental mechanism. Based on these findings, it can be concluded that Fe@C-350 is of significant potential as a promising candidate for the efficient removal of methyl orange from dye-containing wastewater. However, future research is necessary to show its application to the removal of a broader range of contaminants, aiming at enhancing its environmental impact and industrial viability.