Preparation, characterization and evaluation of adsorptive properties of leather waste based activated carbon via physical and chemical activation

In this study, utilization of leather waste (LW) as precursor for activated carbon preparation by physical (steam) and chemical (pyrophosphoric acid, H4P2O7) activation in different conditions (carbonization temperature, carbonization time and impregnation ratio) is discussed. Thermal gravimetric analysis of LW-H4P2O7 indicated that H4P2O7 as the activator promotes the formation of carbonaceous material. The activated carbons obtained under the best conditions were characterized using N2 adsorption/desorption isotherms, X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). The preparation principle of activated carbon with different methods was also studied. Batch adsorption studies were performed to evaluate the adsorption properties toward methylene blue (MB). Activated carbon produced by H4P2O7 activation showed higher yield, lower SBET, more functional groups and higher adsorption capacities for MB than the carbons prepared by steam activation. Adsorption experiment indicated that the adsorption data fitted the Langmuir equation better than Freundlich, Temkin and Dubinin–Radushkevich (D–R) isotherms, and the capacity of adsorption for AC-H4P2O7 was superior to AC-steam, indicating the mechanisms of π–π electron-donor–acceptor (EDA) interaction, cation exchange and hydrogen bond were involved due to the more functional groups. The adsorption has been confirmed to be a spontaneous and endothermic process.

► Leather waste was used as the precursor of activated carbon.
► H4P2O7 was used as the activation agent to make the structure of carbons.
► The properties of carbons prepared by steam and H4P2O7 were discussed.
► Carbon activated by H4P2O7 had more functional groups than that activated by steam.
► Adsorption of methylene blue was well fitted to Langmuir isotherm.