Aminated waste paper membrane for efficient and rapid filtration of anionic dyes and antibiotics from water

Remediation of wastewater with solid waste-based adsorbents is of great environmental significance, but most current waste-based adsorbents suffer from low efficiency. In this work, aminated waste paper (WP-NH₂) membrane is successfully prepared by oxidation of various types of waste paper followed by grafting and crosslinking polyethyleneimine (PEI). WP-NH₂ shows extremely high adsorption for various anionic dyes and antibiotics. Specifically, the adsorption amount for methyl orange (MO) and tetracycline (Tc) are 2156.2 mg·g⁻¹ and 253.7 mg·g⁻¹, respectively. WP-NH₂ is stable enough to be regenerated several times and still maintains high adsorption efficiency. Mechanistic studies show that the adsorption toward anionic MO is mainly through electrostatic interaction and hydrogen bonding, and the adsorption of antibiotic Tc relies on hydrogen bonding and Lewis acid-base reaction. Grafting PEI on the fiber surface enables efficient exposure of adsorption sites. Therefore, WP-NH₂ membrane can quickly, continuously and efficiently filter out MO and Tc from water. After 5800 L·m⁻² MO and 3150 L·m⁻² Tc filtration, the interception rate of the two contaminants is still higher than 90 %. Moreover, WP-NH₂ shows high selectivity and can be used for efficient separation of dye mixture. These results reveal that this advanced adsorbent made from waste paper has great potential application in industrial dye and antibiotic wastewater remediation.