Title: Carboxylic acids-modified palm stones as sorbents for metal ions using single and multi-metal aqueous solutions

Authors: Sameer Al-Asheh, Ahmad Belal

Addresses: Department of Chemical Engineering, Jordan University of Science and Technology, P.O. Box 3030, Irbid 22110, Jordan. ' Department of Chemical Engineering, University of Qatar, P.O. Box 2713, Doha, Qatar

Abstract: Natural palm stone has been modified in order to enhance its sorption capacity for different metal ions. The palm stone (PS), or date-pits, was treated with different carboxylic acids, namely carboxylic acid (CA), tartaric acid (TA), salicylic acid (SA), oxalic acid (OA), mandelic acid (MND) and malic acid (MA). Batch sorption tests were carried out using single, binary or tertiary metal systems composed from copper, zinc and cadmium. In single metal systems, the sorption of metal ions by modified date-pits stone was always higher than that of the unmodified date-pits. The best sorbents used in this work for the removal of Cu, Zn and Cd from their individual solution are SA-PS, CA-PS and MA-PS, respectively. For multi-metal systems, OA-PS and TA-PS can be considered as the best candidates for metal removal. Equilibrium is achieved in a contact time of about an hour. The amount adsorbed was dependent on the process conditions; it increased with an increase in pH, initial metal concentration and amount of sorbet. The Freundlich model agreed very well with the equilibrium isotherm experimental data.

Keywords: palm stone; adsorption; carboxylic acid; tartaric acid; salicylic acid; oxalic acid; mandelic acid; malic acid; batch sorption; biosorption; date pits; metal removal; copper; zinc; cadmium; heavy metals; equilibrium; isotherms; wastewater treatment; water pollution.

DOI: 10.1504/IJEP.2008.020807

International Journal of Environment and Pollution, 2008 Vol.34 No.1/2/3/4, pp.412 - 426

Available online: 16 Oct 2008

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