Removal of Cu2+ from aqueous solution by activated carbon prepared from sawdust and nutshells

In this study, activated carbons were prepared from waste biomass and were used for the removal of Cu 2+ from water.Two sets of activated carbons (10 each): un-oxidized and oxidized were prepared by carrying out the carbonization of the waste biomass in N 2 atmosphere and normal atmospheric air, respectively.Oxidized activated carbons showed high adsorption capacities for the removal of copper ion from aqueous solutions.Surface functional groups (carboxylic, phenol and lactones) were determined quantitatively using Boehm titration method.Langmuir and Freundlich models were used to analyze the adsorption equilibrium data.Best fit was obtained with Langmuir model as the R 2 values were high for almost all the prepared adsorbents in this study.Pseudo-first and pseudo-second order kinetic models were used to analyze the adsorption kinetics data.Best fits were obtained with pseudo-second order kinetic model.The equilibrium time were in range of 30 to 160 min (C 5 = 30 lowest and C 3 /C 8 = 160, highest).The adsorption parameters such as ΔG°, ΔH° and ΔS° were also determined.The values of ΔG° and ΔH° were negative while that of ΔS° were positive.The negative values of ΔH° show that the adsorption of Cu 2+ ions on prepared adsorbents was an exothermic process while the increase in ΔG° values with temperature shows that the adsorption process is favorable one at high temperature.Amongst the oxidized adsorbents (C 1 to C 10 ), activated carbons prepared from Ber and Poplar were more efficient in removal Cu ++ from aqueous solutions.