Preparation of high surface area-activated carbon from lignin of papermaking black liquor by KOH activation for Ni(II) adsorption

Low-cost activated carbon with high surface area was prepared from lignin of papermaking black liquor (BL) by KOH activation with pre-carbonization method. The effects of lignin/KOH ratio, activation temperature and activation time on the BET surface area were investigated. In addition, the adsorption capacity of Ni(II) on BLAC was also studied. Through BET surface area, scanning electron microscopy, Fourier transformed infrared spectroscopy and thermo gravimetric analysis, the BL-activated carbon (BLAC) was discovered to have porous structure with a high surface area up to 2943 m2/g. The results showed that the lignin/KOH ratio was the main factor influencing the surface area and the maximum surface area activated carbon was obtained at lignin/KOH ratio of 3:1, the activation temperature of 750 °C and the activation time of 1 h. The sorption experiments indicated that the pseudo-second-order model was well fitted the kinetic data and the adsorption equilibrium data were better simulated by Langmuir model. The adsorption ability of Ni(II) increased with increasing pH, indicating the electrostatic attraction mechanism.

► KOH activation is used to prepare lignin activated carbon.
► The lignin-activated carbon exhibits high specific surface area.
► The pre-carbonization is adopted to prepare activated carbon.
► Sorption kinetics, isotherm and pH influencing factor are investigated.
► Nonlinear curve-fitting is introduced for analysis.