Coating of PET Textiles with Anionic Cyclodextrin Polymer for Paraquat Removal from Aqueous Solution

Polyethylene terephthalate (PET) textile was coated with anionic cyclodextrin polymer issued by crosslinking between β-CD (β-Cyclodextrin) and BTCA (1,2,3,4-butanetetracarboxylic acid) for paraquat (PQ) removal from aqueous solution. The polymer covering operated by the thermofixation method (170 ºC and 30 minutes) comprised 23.52 % of weight gain, which was related to 0.76 mmol/g of ionic exchange capacity. The functionalized textile was also characterized by FTIR, SEM and TGA. Adsorption experiment was performed employing different parameters such as the pH of the solution, adsorption time, the initial concentration of paraquat and the adsorption temperature. The suitable pH was equal to 8 and the equilibrium time was 420 minutes. At 30 ºC, the adsorption capacity of PQ was increased (5.0, 20.4, and 25.9 mg/g) when the initial concentration of paraquat was enhanced (10, 50, and 250 mg/l). Adsorption kinetics was appropriated to the pseudo-second-order model and adsorption isotherm was fitted to the Langmuir model. Thermodynamic parameters were studied at different temperatures (30, 40, and 50 ºC), in which the negative ΔH displayed an exothermic adsorption process, the negative ΔG showed a spontaneous adsorption process and the positive ΔS revealed an enhanced disorder. Eventually, the recyclability of the modified textile in methanol reached 85 % after four reusability cycles.