Crosslinked electrospinning fibers with tunable swelling behaviors: A novel and effective adsorbent for Methylene Blue

The novel pH and temperature-responsive swellable electrospinning fibers, composed of p( N -Isopropyl acrylamide- co -β-cyclodextrin) (p(NIPAM- co -β-CD)) and p( N -Isopropyl acrylamide- co -Methacrylic acid) (p(NIPAM- co -MAA)), have been fabricated via electrospinning method and the followed ecofriendly thermal-treatment technology for the removal of Methylene Blue (MB). Introduced Acryloyl-β-CD and MAA offered the copolymers active groups for the crosslinking reaction within the fibers, providing improved water resistance in the pH range from 3 to 11 and higher swelling capacity reaching to 6942.2%. In the batch adsorption experiment, the adsorption capacity of the fibers for MB increased by 60% approximately as the temperature increasing from 25 °C to 55 °C, and the maximum adsorption capacity reached to 1834.97 mg/g. And the regeneration efficiency of the fibers kept above 84% after six times adsorption+desorption cycles. The adsorption process fitted well pseudo-second-order kinetic model, indicating the chemisorption process driven by the electrostatic interaction between –COOH groups of the fibers and MB molecules. And the Weber-Morris diffusion model demonstrated that the intra-particle diffusion was not the only rate-determining step during the adsorption process. Furthermore, the Langmuir model revealed that the monolayer adsorption occurred on the energy-homogenous surface. These characteristics make the stimuli-responsive fibers promising candidates as adsorbent for the purification of wastewater.