Development of a Fluorescent Nanocomposite System (AlgMMT@BDots) Embedding Carbon Quantum Dots Derived From Babassu (Attalea speciosa) Fibers for Optical Detection and Integrated Removal of Water Pollutants

The contamination of water resources by organic and emerging pollutants requires the development of multi-functional materials capable of simultaneous remediation and monitoring. Herein, we report an innovative, eco-friendly dual-functional nanocomposite (AlgMMT@BDots) designed through the strategic immobilization of fluorescent carbon quantum dots derived from Amazonian Babassu ( Attalea speciosa ) fibers into an alginate-montmorillonite hydrogel matrix. Unlike conventional systems, the structural integration of these biopolymer-derived BDots triggers a synergistic morphological rearrangement, promoting clay lamellar disorder and expanding the fibrous network. This architectural shift was quantitatively confirmed by BET analysis, which revealed a massive four-fold increase in specific surface area (from 480.2 to 1063.1 m 2 /g) and a 15-fold expansion in total pore volume, along with an optimized swelling capacity (1045%). Functionally, the AlgMMT@BDots platform demonstrates high coupled efficiency for both remediation and optical sensing: it acts as an effective bulk adsorbent and highly sensitive chemosensor, with methylene blue (MB) exhibiting superior uptake and fluorescence quenching efficiency (K SVa = 8.5 M⁻ 1 ; log K a = 0.33) compared to estradiol valerate (EV) (K SVa = 6.6 M⁻ 1 ; log K a = 0.21) driven by synergistic electrostatic and surface state interactions. The Limit of Detection (LOD) of 0.28 µg/L and Limit of Quantification (LOQ) of 0.93 µg/L to the chemosensor were calculated. The material demonstrated excellent mechanical and optical stability over five consecutive cycles. This study advances the practical design of sustainable biocomposites, bridging circular regional economy with high-performance real-time water monitoring and remediation.