High-efficiency adsorption of tetracycline by the prepared waste collagen fiber-derived porous biochar

Porous biochar (PBC) derived from Cr-containing waste collagen fibers was prepared by two-step pyrolysis to 800 degrees C (PBC-800) and alkali activation. Brunauer-Emmet-Teller (BET) analysis, scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), X-ray fluorescence (XRF), thermogravimetric analysis (TGA) and zeta potential analysis were used to characterize PBC-800. Batch experiments showed that PBC-800 had an excellent removal effect on tetracycline (TC), and the maximum adsorption capacity was 593.84 mg g(-1). Meanwhile, PBC-800 was found to be suitable for a wide pH range. The isothermal adsorption and kinetic model fitting proved that the TC adsorption by PBC-800 occurred via 5 types of chemical adsorption. The main rate-limiting step was closely related to the initial concentration of TC. The total release of Cr was less than 0.05 mg L-1, which indicated that PBC-800 was stable and did not cause serious secondary pollution. Compared to the conventional metal-free biomass, Cr in a waste collagen fiber (WCF) played an important role in carbon formation and adsorption. The excellent adsorption properties of PBC-800 indicated that it could enrich low concentrations of TC in water. Thus, WCF can be used to prepare cost-effective PBC, which supplies a new process to reuse Cr-containing waste.