2,4-Dinitrophenol adsorption by date seeds: Effect of physico-chemical environment and regeneration study

The main goal of this research was to evaluate the adsorption capability of non-conventional, low-cost adsorbents at elevated 2,4-dinitrophenol (DNP) concentrations. Commercial activated carbon was also evaluated in an attempt to identify the sorption mechanism. Isotherms for adsorption of 2,4-dinitrophenol from water and basal salt medium onto date seeds and activated carbon were determined. These isotherms were modeled by the Freundlich isotherm. The experimental results showed that only 0.5 g of date seeds, with a 125 ml salt medium. were a suitable adsorbent for the removal of DNP from samples. The studies showed date seeds to be an efficient sorbent material for DNP removal from solutions. Of the parameters investigated, pH was determined to be most crucial, with an optimum pH range of 4.0 to 5.0 for good DNP removal. The DNP adsorption capacity of both adsorbents exceeded the original value of the raw material when regenerated by microwave irradiation. The regeneration efficiency of date seeds was 96% compared to 85% of activated carbon. In addition, the use of basal salt medium solution does not appear to play a significant role in DNP adsorption by activated carbon compared to water medium. However, the basal salt medium was associated with a higher adsorption capacity when used with date seeds. Finally, the treatment of a high DNP concentration with date seeds and activated carbon significantly reduced the toxicity of the DNP effluent. (C) 2009 Published by Elsevier B.V.