A practical and environmentally sustainable approach to dye removal: Synthesis and characterization of a highly efficient crosslinked chitosan-Schiff base adsorbent for Eriochrome Black T removal.

The removal of dyes from aquatic environments is crucial amidst the growing demands of industrialization and environmental sustainability. This study focuses on fabricating a novel crosslinked chitosan adsorbent with high adsorption capacity to remove EBT dye effectively. The synthesis of the adsorbent involved a two-step process: condensation with pyridine-3-carbaldehyde followed by crosslinking with 1,1'-(piperazine-1,4-diyl)bis(2-chloroethan-1-one). The synthesized adsorbent, designated as Cs-Py1-Pz, was characterized using techniques such as TGA, H NMR, BET, SEM, EDX, XPS, XRD, and FTIR. The effects of controlling factors, including initial concentration, temperature, pH, contact time, and dosage, on adsorption performance were investigated. Based on the Langmuir isotherm model, the Cs-Py1-Pz adsorbent exhibited a maximum adsorption capacity of 1640.04 mg g for EBT dye removal at 298 K. Furthermore, the pseudo-first-order model best described the experimental kinetic data. While the intraparticle diffusion mechanism influenced the adsorption process, it was not the sole controlling factor. Combined theoretical and experimental thermodynamic studies suggested that the interaction between EBT dye and Cs-Py1-Pz is likely governed by a physical process occurring spontaneously and exothermically. Reusability studies demonstrated successful regeneration of the adsorbent using NaOH as an eluent. Notably, Cs-Py1-Pz exhibited significant antibacterial activity against E. coli growth, with a 66.7 % inhibition rate. Overall, these findings highlight Cs-Py1-Pz as a promising adsorbent with a high capacity for the effective removal of EBT dye from aqueous solutions.