Analysis of influence of process conditions on kinetics of malachite green biosorption onto beech sawdust

Beech sawdust was used as cheap and productive biosorbent enabling removal of cationic dye, malachite green, from water solutions. Impact of many process parameters upon malachite green biosorption was investigated to explain mechanism of the process. Process kinetics was carried out with various values of pH (3–12), temperature (20–50 °C), sorbent concentration (1.25–5 g L−1), dye concentration (10–100 mg L−1), ionic strength (0–5% w/w NaCl), anionic surfactant concentration (0–5 mM SDBS). Models based on reaction order and model based on diffusive transport in sorbent pores described well the kinetics. Redlich–Peterson model correlated best with equilibrium points. The maximum adsorption capacity of beech sawdust was 83.21 mg g−1 in 20 °C. There were also determined thermodynamic parameters which prove that malachite green biosorption is spontaneous, feasible and endothermic within investigated temperature range.

► Beech sawdust as a sorbent of cationic dyes.
► Environmental factors influence biosorption.
► Removal of dyes from wastewater.