Seeking the adsorption of tetracycline in water by Fe-modified sludge biochar at different pyrolysis temperatures.

The composite material SBC-Fe-x with sludge and Fe was developed by different calcination temperatures (600, 700, and 800 °C) for the removal of tetracycline (TC). The adsorption rates of SBC-Fe-600, SBC-Fe-700, and SBC-Fe-800 were 77.5%, 89%, and 91%, respectively. Furthermore, the Langmuir model indicated that the maximum adsorption capacity of SBC-Fe-700 (157.93 mg/g) was three times greater than that of SBC-Fe-600. The conclusions were confirmed by a series of characterizations that SBC-Fe-700 showed a larger specific surface area, well-developed pore structure, rich oxygen-containing functional groups and a high degree of graphitization. The results of pH experiments indicated the broad applicability of SBC-Fe-700 for TC adsorption. In addition, SBC-Fe-700 suggested outstanding performance in different water environments. This work produced a feasible adsorbent for the removal of TC, and a new direction for sludge resource utilization was proposed.