Waste napkin biochar with high-performance designed for antibiotic rapidly removal

In this work, domestic refuse waste napkin (WN) was used as raw material, modified by different dyes and prepared to N-doped biochars via carbonation and activation methods. The results showed that the addition of dyes not only optimized the physicochemical properties of biochars, but also greatly improved the adsorption performances. The specific surface areas of N-doped biochars (BWN-CR, BWN-CV, and BWN-MO) were increased by 5.95–26.6 % compared with that of undoped biochar (BWN, 2173.13 m 2 /g), similarly, the content of nitrogen atoms in the modified biochars increased by 0.50–2.03 times. In the adsorption experiments using tetracycline hydrochloride as adsorption model, the adsorption capacities of all N-doped biochars (938.71–1159.05 mg/g) were greater than that of most adsorbents including BWN (861.33 mg/g). After 10 cycles of use, both all of the biochars can still maintain more than 65 % of the performance, indicating their stable regeneration ability. This work not only prepared a series of biochars that can be used to efficiently remove antibiotics from water, but more importantly provided a new strategy for the high-value utilization of WN and further released the application potential of secondary resources. • Different synthetic dyes were used to modify waste napkin with N-doping. • Biochars with enhanced high-performance were prepared from waste napkin. • N-doped biochars have larger specific surface area and highly total pore volume. • The maximum adsorption capacities of biochars are higher than most adsorbents.