Efficient removal of tylosin by nitrogen-doped mesoporous carbon nanospheres with tunable pore sizes

Efficient and selective removal of antibiotics from wastewater is quite important but challenging. In this work, the nitrogen-doped mesoporous carbon nanospheres (NMCN) with different pore size (from 2.67 to 4.62 nm) were successfully prepared by changing the hydrothermal condition, and their removal performance on tylosin was evaluated. The adsorption experimental data were fitted well with the pseudo-second-order kinetic model. Besides, Langmuir isotherm model could better describe the adsorption process. Notably, the NMCN with medium pore size (3.36 nm) exhibited the highest adsorption capacity (1333 mg g^-1), which was 24% and 14% higher than that of NMCNs with smaller and larger pore size, respectively. In order to study the adsorption mechanism, the mesoporous carbon nanospheres without N-doped was prepared, and the comparison of nitrogen adsorption-desorption isotherms was conducted. The result proved that in addition to the modified surface property, large specific surface area, and high pore volume, the pore size could precisely influence the adsorption performance of the proposed adsorbent. Furthermore, the proposed NMCN material possessed a selective adsorbing ability toward tylosin in the presence of tetracycline. Clearly, the NMCN was a promising alternative to be used as high efficient and selective adsorbent in practical environment pollution treatment, especially in large-size molecule adsorption.