Chitosan-coated nonwoven polyethylene terephthalate material for efficient removal of cationic and anionic dyes from aqueous solution

A simple dye adsorbent based on polyethylene terephthalate - PET functionalised by chitosan'Chit-Pet-T' was developed to remove cationic (MG, CV) and anionic (SY, DB71, AY17) synthetic dyes from aqueous solutions. In the first part of this study, the surface of the non-woven PET material was activated by using an aqueous solution of NaOH (0.5 M), and then the surface of the alkaline activated PET was functionalised by treatment with an acidic aqueous solution of chitosan. The Chit-Pet-T was then characterised by physicochemical methods: X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), zeta potential,energy-dispersive X-ray spectroscopy (EDS), air permeability and water contact angle measurements (WCA). The physicochemical characterisation of Chit-Pet-T confirmed the successful immobilisation of the chitosan on the surface of the non-woven PET with a coating ratio of 46%. The dye adsorption studies show that the capacity of Chit-Pet-T to adsorb the studied dyes is affected significantly by the initial pH, Chit-Pet-T dose, ionic strength, temperature and initial dye concentration. The removal rate (R) reached the maximum value at pH = 11 and pH = 2 for the cationic (MG: 91%, CV: 90%) and anionic (SY: 95%, DB71: 96%, AY17: 94%) dyes, respectively, within 300 min, under a wide range of temperature, with dye solution of 0.1 M. The Langmuir isotherm model could be best adequate to describe the dye adsorption onto Chi-Pet-T and the thermodynamic parameters indicated that the adsorption was a spontaneous exothermic process. The excellent performance and regeneration capabilities demonstrate that Chi-Pet-T can be used as a potential efficient and recyclable adsorbent for removal of cationic and anionic dyes from wastewaters.