Studies on adsorption of p-nitrophenol on charred saw-dust

An effective adsorbent developed from common sawdust has been used for the removal of p-nitrophenol from aqueous solution. It is observed that the degree of agitation has a significant effect on the rate of removal of p-nitrophenol. Higher initial concentration and lower temperature are more favorable for the adsorption of p-nitrophenol. The experimental results confirmed that the intraparticle diffusion has a hindering effect on the adsorption rate. An external mass-transfer model has been applied to interpret the rate data. The values of fluid-particle mass-transfer coefficient obtained from the experimental data have been compared with the predicted value. The mass-transfer coefficient is found to decrease with increasing concentration of p-nitrophenol. Adsorption equilibrium data fit most satisfactorily with the Langmuir adsorption isotherm. (C) 2001 Elsevier Science B.V. All rights reserved.