Adsorptive efficacy analysis of lignocellulosic waste carbonaceous adsorbents toward different mercury species

•Lignocellulosic wastes derived adsorbents were successfully synthesized.•Activated carbon shows high adsorptive efficacy toward Hg2+.•Char shows high adsorptive efficacy toward MeHg+.•Isotherm and kinetic data obeyed the Langmuir and PSO models, respectively.•Adsorption process was governed by reaction kinetic and diffusion mechanisms.

Adsorptive efficacy of lignocellulosic waste char (LW-CHAR) and activated carbon (LW-AC) toward inorganic (Hg2+) and organic (MeHg+) mercury ions was studied. The LW-CHAR and LW-AC were, respectively, prepared by carbonization and KOH activation processes of lignocellulosic waste (LW) carried out at 700 °C. The Hg2+ adsorption onto the LW-CHAR was lower than LW-AC, however, an opposite result was observed for the MeHg+ indicating the nature of the surface interactions of both mercury ions to respective adsorbent surfaces was significantly different. The adsorption data analysis of both mercury ions was found however to only follow the Langmuir isotherm and pseudo-second order kinetic models whereby a combination of chemisorption and diffusional process was the governing mercury ions adsorption mechanism.