Adsorptive Sequestration of Nitrophenol from Phenol Mixture onto Locust Bean Tree Sawdust

The efficacy of an adsorbent prepared from sawdust of Locust bean tree to remove 4-Nitrophenol
(4NP), from its aqueous solution and from binary and ternary mixture of phenols (with phenol or / and
chlorophenol) was studied. Batch adsorption procedures were carried out to investigate the kinetics,
isotherms and thermodynamics of the adsorptive removal, as well as the influence of sawdust
dosage, pH, initial concentration of the phenols and temperature on the efficiency of the process.
Equilibrium was attained at 12 hours, with the optimum sawdust concentration of 5 g/L. The kinetics of
the adsorption could best be described by pseudo-second order model, while Freundlich isotherm
gave the best fit in all the systems studied. The adsorption process was thermodynamically nonspontaneous
at low temperatures as ΔG was positive; but it was endothermic in the single, binary and
ternary systems.