Kinetic and adsorptive characterization of biochar in metal ions removal

Kinetic and adsorption studies on the removal of metal ions such as Cu(II), Zn(II), Cd(II) and Pb(II) ions in the biochar (BC) samples have been carried out. The effects of several experimental parameters have been investigated using the batch adsorption technique at different temperature. The effectiveness of Cu(II), Zn(II), Cd(II) and Pb(II) ions removal increases with the increasing initial concentration of biochar and metal ion, pH as well as phase contact time. The maximum adsorption was found in the pH range 5.0–6.0. The kinetics of adsorption was found to be pseudo second order with intraparticle diffusion as one of the rate determining steps. Adsorption studies were also performed at different temperatures and modelled with the Langmuir and Freundlich adsorption isotherms.

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► Biochars effectively removed metal ions from aqueous solutions.
► Pyrolysis at 400 °C seems optimal producing biochar as the effective metal ions sorbent.
► The maximum removal was obtained in the pH range 5–6.
► The adsorption kinetic was described well by the pseudo second order model.
► The intraparticle diffusion was not the only rate controlling step of the adsorption process.