Extraction of p-Nitroaniline from Aqueous Solutions onto Activated Carbon Prepared from Treated Camphor Wood

In this study, the residues of camphor wood were used to produce activated carbon by pyrolysis. The prepared carbon was treated by potassium dihydrogen phosphate and then used as a solid phase adsorbent for the removal of p-nitroaniline (PNA) from aqueous solutions. A commercial camphor activated carbon (CC) adsorbent was selected for comparison purposes. Liquid phase adsorption experiments were conducted, and the maximum adsorptive capacity was determined. The effect of pH, electrolyte, temperature, and grain size on the adsorption process was also studied. The obtained experimental data were fitted with the Langmuir and Freundlish models to describe the equilibrium isotherms. The kinetic rates were modeled by using the pseudo-first order and the pseudo second order equations. The results indicated that treated camphor wood activated carbon (TCC) is an effective adsorbent for the removal of PNA from aqueous solution. The maximum adsorption capacity of 160 mg g-1 (~80% removal) was achieved at initial PNA concentration of 200 mg L-1 at pH=7.0 and 250C. The presence of ammonium chloride proved to be favorable for the adsorption process. The Langmiur model was found to best represent the equilibrium data. The kinetic rates followed closely the pseudo-second order equation. The thermodynamic study showed that the adsorption was a spontaneous exothermic physical process. KeywordsCommercial camphor activated carbon; pnitroaniline; Solid phase extraction; Adsorption capacities.