Removal of 2,4,6-trichlorophenol from aqueous solutions using agricultural waste as low-cost adsorbents

Agricultural waste products including sunflower seed hulls, pumpkin seed shells, walnut shells and peanut shells were used as low-cost adsorbents for the removal of 2,4,6-trichlorophenol (TCP) from aqueous solutions. The effects of adsorbent dosage, pH and ionic strength on the adsorption of TCP were investigated. The results showed that the adsorption of TCP was pH dependent and increased upon increasing the ionic strength of the solution. The adsorption kinetics was found to follow a pseudo-second order kinetics. The equilibrium adsorption data were fitted to the Langmuir, Freundlich and Sips isotherms and the best results were achieved with the Freundlich model. The desorption of TCP using deionized water, water/methanol mixture or 5% sodium hydroxide was also studied. The results suggest that the tested materials may be used as an effective adsorbents without any treatment or any other modification for removal of TCP from the aqueous medium.