Facile and Scalable Fabrication of Antibacterial CO₂-Responsive Cotton for Ultrafast and Controllable Removal of Anionic Dyes

Abstract

A novel CO₂-responsive cotton as an eco-friendly adsorbent derived from poly(4-acryloyloxybenzophenone-<i>co</i>-2-(dimethylamino) ethyl methacrylate) and cotton was fabricated via a facile and fast dip-coating method. As expected, upon CO₂ stimulation, the protonated cotton presented CO₂-induced "on-off" selective adsorption behaviors toward anionic dyes owing to electrostatic interactions. The adsorption isotherms and kinetics of the CO₂-responsive cotton toward anionic dyes obeyed the Langmuir isotherm and pseudo-second-order kinetics models, respectively. It is noteworthy that the CO₂-responsive cotton exhibited high adsorption capacity and ultrafast adsorption rate toward anionic dyes with the maximum adsorption capacities of 1785.71 mg g^-1 for methyl orange (MO), 1108.65 mg g^-1 for methyl blue (MB), and 1315.79 mg g^-1 for naphthol green B (NGB), following the adsorption equilibrium times of 5 min for MO, 3 min for MB, and 4 min for NGB. Moreover, the CO₂-responsive cotton also exhibited high removal efficiency toward anionic dyes in synthetic dye effluent. Additionally, the CO₂-responsive cotton could be facilely regenerated via heat treatment under mild conditions and presented stable adsorption properties even after 15 cycles. Finally, the as-prepared CO₂-responsive cotton exhibited outstanding antibacterial activity against <i>E. coli</i> and <i>S. aureus</i>. In summary, this novel CO₂-responsive cotton can be viewed as a promising eco-friendly adsorbent material for potential scalable application in dye-contaminated wastewater remediation.