Adsorption of estrogenic hormones in aqueous solution using electrospun nanofibers from waste cigarette butts: Kinetics, mechanism, and reusability

This study emphasizes rapid and simultaneous adsorptive removal of estrogenic hormones (EH): estrone (E1), estradiol (E2), ethinylestradiol (EE2), and estriol (E3) from wastewater using recycled waste cigarette electrospun fibers (WCENFs). The submicron fibers exhibited a strong affinity towards all EH due to abundant hydrogen bonding interactions. The adsorption kinetics pseudo-first-order, pseudo-second-order, intra-particle diffusion, Elovich, and fractional power models were explored and fitted towards optimum conditions for the large-scale removal process of the EH. Results showed that E1, E2, and EE2 followed pseudo-second-order kinetics while E3 followed the pseudo-first-order kinetic model. In combination, the total adsorption capacity achieved was 2.14 mg/g, whereas the individual values for E1, E2, EE2, and E3 were 0.551, 0.532, 0.687, and 0.369 mg/g, respectively. The percentage efficiency of WCENFs was highest with EE2 ~64.3% and least with E3 ~34.6%. The WCENFs could repeatedly be used for four adsorption-desorption cycles as an effective adsorbent for the simultaneous removal of four EH via batch adsorption studies. According to the results obtained, the repurposing of waste cigarette butts to WCENFs presented itself as a suitable alternative for removing EH and possibly other organic pollutants from water.