Background and Aims: Cresol is an extremely toxic phenolic compound even at low concentrations which can be found in industrial effluents. The aim of this study was, therefore, to assess the ability of modified Azolla and Lemna minor in p-cresol removal from aqueous solution.Materials and Methods: In the present empirical-bench scale study, we activated the Azolla and Lemna minor by 0.1M HCl and dried in the oven at 105 °C for 24 h. The effects of contact time, pH, initial cresol concentration and biomass amount on adsorption performance were investigated. Adsorption isotherms and kenitics were then used to explain the gathered experimental data. The concentration of p-cresol wasmeasured by UV-VIS spectrophotometer at 280 nm.Results: The results indicated that although the efficiency of p-cresol removal increased by increasing both contact time and the amount of bioadsorbent, the adsorption capacities [qe], however, decreased either in the case of Azolla or Lemna minor. The adsorption capacity also decreased by increasing initial p-cresol concentration. The optimum pH of p-cresol removal was 3. The adsorption process followed the Langmuir isotherm and pseudo-second-order kinetic.Conclusion: According to our results, Azolla and Lemna minor can be used as effective and affordable adsorbents for the removal of phenolic compounds from industrial effluents.Key words: Adsorption, Azolla, Lemna minor, p-creso
