Metal-Organic Frameworks with Linear and Branched Polyol Backbones for Dye Removal

In this study, novel metal-organic frameworks (MOFs) were synthesized using functionalized polyols as ligands. Polyvinyl alcohol (PVA) and hyperbranched polyglycerol (hPG) were first mesylated and subsequently modified with 5-aminoisophthalic acid. These functionalized polymers were then reacted with iron (III) chloride hexahydrate to form related MOFs including PVA-MOF and hPG-MOF. The resulting MOFs exhibited high adsorption capacities for both cationic dyes (Rhodamine B and Methylene Blue) and an anionic dye (Fluorescein) from aqueous solutions. Adsorption studies revealed that dye removal followed the Langmuir isotherm model, with maximum capacities reaching 128.17–135.34 mg.g ^− 1 depending on the type of dye and MOF. Thermodynamic analysis showed that adsorption was endothermic, with increased entropy, and spontaneous for the anionic dye, while non-spontaneous for the cationic dyes. The materials also demonstrated excellent structural stability and regeneration potential over three adsorption-desorption cycles. Furthermore, performance was confirmed using real water samples, indicating that PVA-MOF and hPG-MOF are promising, reusable adsorbents for efficient dye removal in wastewater treatment.