Removal and recyclable chitosan nanowires: Application to water soluble dyes

In this research experiment, the potential of chitosan nanowires for the removal of cationic dyes which were Methylene Blue (MB) and Reactive Red l41 (RR-141) from wastewater was investigated. Chitosan powder was prepared from shrimp shells, then, chitosan nanowires were synthesized with the ionic gelation method, using sodium tripolyphosphate as a crosslinking agent under mild conditions. The appearance of functional groups of pure chitosan nanowires, together with 81% degree of acetylation and 110.2 m(2) g(-1), were achieved. TEM image revealed the incorporation of dye within the chitosan structures. The adsorption capacity was affected significantly by the amount of chitosan present, contact time, pH and dye concentration. The highest removal rates of MB and RR-141 were 91.5% and 82.74% respectively, within 60 min with dye solution of 75 mg L-1 at pH 4 and 10 g chitosan, and the uptake capacity remained around 82.3-91.5% for 3 regeneration cycles. The adsorption isotherm correlated well with Langmuir and the Freundlich isotherms. Therefore, eco-friendly bio-chitosan could be applied successfully for dye contaminated wastewater remediation. Rather than a lab scale, further commercial process should be applied for higher effective performances. (C) 2020 The Authors. Published by Elsevier B.V.