Effect of Physical and Chemical Activation on the Removal of Hexavalent Chromium Ions Using Palm Tree Branches

Abstract

Nowadays the removal of heavy metals from wastewater is essential due to their high toxicity and impact on human health. In the present study, branches of palm trees were converted into activated carbon by chemical and physical activation. The prepared samples were used for the removal of Cr(VI) from their aqueous solution. Chemical activation was carried out using (20 and 50%) H 3 PO 4 and K 2 CO 3 , and physical activation was performed using steam. Batch adsorption experiments were carried out to examine the removal process under factors such as pH and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mtext>p</mml:mtext><mml:msub><mml:mrow><mml:mtext>H</mml:mtext></mml:mrow><mml:mrow><mml:mtext>pzc</mml:mtext></mml:mrow></mml:msub></mml:math>. The metal ion removal was pH dependent and reached maximum removal at pH 2. Experimental data were analyzed using Langmuir, Freundlich, and Flory-Huggins isotherms. The adsorption studies revealed that the removal of Cr(VI) ions was well fitted with Langmuir isotherm. The adsorption kinetics well fitted using a pseudo second-order kinetic model. Column studies revealed that the highest bed volume (60 BV) was observed for the sample activated with 50% H 3 PO 4 . The adsorption efficiency was enhanced with acid treatment (50% H 3 PO 4 ) and reduced by steam.