Waste cotton-based activated carbon with excellent adsorption performance towards dyes and antibiotics

A novel adsorbent is prepared from waste cotton fiber by a simple pyrolysis-activation process, and it can efficiently adsorb many kinds of organic pollutants (cationic/anionic dyes and antibiotics etc.). The obtained cotton-based activated carbon (CAC) with large specific surface area (3709 m² g^-1) and suitable pore structure provide abundant active sites and fast channels for the adsorption of pollutant molecules. Its saturated adsorption capacities towards methylene blue, Congo Red and tetracycline hydrochloride at room temperature can reach to 2331, 7265 and 1250 mg g^-1, respectively. In addition, the optimal sample also exhibits excellent adsorption ability towards Rhodamine B (1327 mg g^-1), methyl orange (955 mg g^-1) and ciprofloxacin hydrochloride (824 mg g^-1). The adsorption involves a multi-process including pore filling, Van der Waals force interaction, electrostatic attraction, hydrogen bond formation, surface complexation and π-π stacking etc. The CAC adsorbent also exhibits excellent resistance to environmental disturbances (pH, coexisting ions and multicomponent systems etc.) and good regeneration/recycling performance. This study develops a high-efficiency biomass-based adsorbent with excellent adsorption performance and application generality, which has great potential in wastewater treatment.