Enhanced visible-light removal of Auramine O using carbon dots–integrated MIL-100(Fe) photocatalyst

The removal of Auramine O (AO), a carcinogenic and persistent cationic dye, remains a significant challenge in wastewater treatment. Accordingly, carbon dots (CDs) were combined with the Fe-based metal–organic framework (MOF), MIL-100(Fe), through water-assisted liquid-assisted grinding to produce a hybrid photocatalyst. CDs were derived from henna ( Lawsonia inermis ) using a one-step hydrothermal method and subsequently integrated into the MOF at varying loadings (1–10 wt%). Characterization by XRD, FTIR, and FE-SEM confirmed the successful incorporation of CDs, revealing a preserved crystalline structure with enhanced surface interactions. The optimized composite containing 5 wt% CDs removed 93 % of AO within 240 min, with an empirical rate constant (k) of 0.0013 L mg⁻¹ min⁻¹, and outperformed pristine MOF. The improvement was associated with broader visible-light absorption and reduced radiative charge recombination following CD incorporation. This work presents a facile, green mechanochemical strategy for fabricating MOF-based composites for effective wastewater remediation.