%0 Journal Article
%T Effect of Physical and Chemical Activation on the Removal of Hexavalent Chromium Ions Using Palm Tree Branches
%A Soheir Khedr
%A Mona Shouman
%A Nady Fathy
%A Amina Attia
%J ISRN Environmental Chemistry
%D 2014
%R 10.1155/2014/705069
%X 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%) H3PO4 and K2CO3, and physical activation was performed using steam. Batch adsorption experiments were carried out to examine the removal process under factors such as pH and . 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% H3PO4. The adsorption efficiency was enhanced with acid treatment (50% H3PO4) and reduced by steam. 1. Introduction The discharge of heavy metals into the environment has been increasing continuously due to rapid industrialization and has created a major global concern. The release of these heavy metals causes a significant hazard to human health and the environment because of their toxicity, accumulation in living tissues, and consequent biomagnifications in the food chain [1, 2]. Among the different heavy metals in concern is chromium. Compounds of chromium mainly occur in the environment as trivalent Cr(III) and hexavalent Cr(VI). Trivalent chromium is an essential element in human nutrition (especially in glucose metabolism) and is less toxic than the hexavalent state, which is recognized as a carcinogenic and mutagenic agent [3]. Acute exposure to high levels of Cr(VI) can produce nervous system damage and liver disorder. EPA (Environmental Protection Agency) has set the maximum level of total Cr concentration allowed in drinking water at 0.1£¿mg£¿L£¿1 [4]. Chromium and its compounds are widely used in electroplating, leather tanning, cement, dying, metal processing, wood preservatives, paint and pigments, textile, steel fabrication, and canning industries. In Egypt, about 2000¨C5000 tons of chromium pollute the environment annually from several industries in the aqueous effluent compared to the recommended permissible discharge limits of 2£¿mg£¿L£¿1 [5]. Conventional methods for removing dissolved heavy metal ions include chemical precipitation, chemical
%U http://www.hindawi.com/journals/isrn.environmental.chemistry/2014/705069/