Insights into properties of activated carbons prepared from different raw precursors by pyrophosphoric acid activation.

Low-cost activated carbons (ACs) were prepared from four kinds of solid wastes: petroleum coke, Enteromorpha prolifera, lignin from papermaking black liquid and hair, by pyrophosphoric acid (H4P2O7) activation. Thermo-gravimetric analysis of the pyrolysis of H4P2O7-precursor mixtures implied that H4P2O7 had different influences on the pyrolysis behavior of the four raw materials. N2 adsorption/desorption isotherms, scanning electron microscopy, Fourier transform infrared spectroscopy and adsorption capacities for dyes were used to characterize the prepared activated carbons. AC derived from E. prolifera exhibited the highest surface area (1094m(2)/g) and maximum monolayer adsorption capacity for malachite green (1250mg/g). Kinetic studies showed that the experimental data were in agreement with the pseudo-second-order model. The adsorption isotherms were well described by the Langmuir isotherm model, indicating the adsorption of dye onto the ACs proceeded by monolayers.