Equilibrium and kinetic studies in remediation of heavy metals in landfill leachate using wood-derived biochar

Effective removal of heavy metals from landfill leachate is of great concern due to the fact that toxic metals can seriously threaten soil and water resources, and therefore the human health. The adsorption of lead(II), zinc(II), and nickel(II) in fresh landfill leachate onto wood-derived biochar was studied and modeled. The influence of contact time, adsorbent dosage as well as particle size was investigated. Wood-derived biochar produced under the pyrolytic temperature of about 740 degrees C was used in two forms i.e. pulverized (PWB) and crushed (CWB) as adsorbent in this study. The kinetics of Pb, Zn, and Ni adsorption onto PWB and CWB were excellently represented by the pseudo second- order model with very high values of determination coefficient (R-2 = 0.999) and low sum of error square (SSE). The Langmuir, Freundlich, Elovich and Temkin models were applied to the experimental data to predict the adsorption parameters. Linearization technique for the Langmuir isotherm which can alter the error structure was also studied in the present work. The Temkin isotherm best represents the equilibrium adsorption data for both PWB and CWB. Other used isotherms unable to describe adsorption of Pb, Zn, and Ni onto CWB. PWB was found to uptake the studied heavy metals more effective than CWB in leachate system. Findings of this research demonstrated the applicability of wood-derived biochar as an alternative to activated carbon for the effective adsorption of the heavy metals from landfill leachate system.