Reusable nanofibrous adsorbent functionalized with MIL-101(Fe)/Graphene oxide for Azo dye remediation from textile effluents: functionalization, kinetics, and mechanism insights

Water scarcity and declining water quality, fueled by uncontrolled industrialization and population growth, have rendered water security a critical global challenge. A principal contributor to this ecological threat is the indiscriminate discharge of industrial effluents, especially dyes, into aquatic systems. As a remedial strategy, electrospun polyacrylonitrile nanofibers integrated with MIL-101(Fe) and graphene oxide (E-spun PAN/MIL-101(Fe)/GO NFs) were engineered as a high-performance and cost-effective adsorbent. Its analytical applicability was demonstrated using a thin-film solid-phase microextraction (TF-SPME) platform, followed by UV-Vis detection, for the sequestration of methyl orange (MO) and congo red (CR), two anionic azo dyes, from textile industry wastewaters (TIWWs). The integration of these materials into the polymeric network imparted exceptional attributes, including a satisfactory specific surface area (SSA, 21.48 m² g^-1), augmented functionalities, enhanced extractability (2.27-fold for MO and 2.54-fold for CR), desirable adsorption capacities (108.015 mg g^-1 for MO and 102.704 mg g^-1 for CR), and exemplary reusability (< 5% loss after 15 cycles). Electrostatic interactions, hydrogen bonding, and π-π stacking were identified as the predominant driving forces governing this mechanism. The proposed methodology offered satisfactory analytical merits, including an expansive linear dynamic range (LDR: 0.05-3.0 mg L^-1), low limits of detection (LODs: 0.017 mg L^-1 for MO and 0.026 mg L^-1 for CR), a low limit of quantification (LOQ: 0.05 ​​mg L^-1), and adequate precision (RSD%: 2.52-4.60%). The experimental outcomes validated that the proposed TF-SPME/UV-Vis technique, employing E-spun PAN/MIL-101(Fe)/GO NFs, offers a promising approach for the sequestration of pollutant dyes and the remediation of contaminated waters.