In situ fabrication of cellulose-supported aluminum-glutamate complexes for highly efficient adsorption of indigo carmine

Green-synthesized Al-CPs@CMC using CMC and l -glutamic acid. • High IC adsorption capacity (434.783 mg/g), following Langmuir and PSO models. • Excellent reusability (>80% removal after 5 cycles) demonstrates good stability. • Provides a sustainable strategy for anionic dye removal from wastewater. Based on the principles of green chemistry, a novel aluminum-based coordination polymer composite was successfully prepared via a mild aqueous coprecipitation method using carboxymethyl cellulose (CMC) and l -glutamic acid ( l -Glu) as building blocks. The as-prepared material exhibited excellent selective adsorption performance towards the anionic dye indigo carmine (IC). The adsorption behavior was well described by the Langmuir monolayer model and pseudo-second-order kinetic model, with a theoretical maximum adsorption capacity of 434.783 mg/g. Thermodynamic analysis indicated that the adsorption process was spontaneous and exothermic. Mechanism studies revealed that the adsorption was predominantly driven by electrostatic attraction between the protonated amino groups on the composite surface and the dye anions, supplemented by hydrogen bonding and coordination interactions. After five consecutive adsorption–desorption cycles, the removal efficiency for IC remained above 80%, demonstrating good stability. This work provides a new strategy for developing efficient, green, and biodegradable materials for the treatment of dye-containing wastewater.