Chitosan/Carbon Nanotube Composite Beads: Preparation, Characterization, and Cost Evaluation for Mercury Removal from Wastewater of Some Industrial Cities in Egypt Hosam A. Shawky, 1,2 Abdel Hameed M. El-Aassar, 1 Dalia E. Abo-Zeid 3 1 Water Treatment & Desalination Unit, Desert Research Center, El-Matariya, P. O. Box 11753, Cairo, Egypt 2 Center of Nanotechnology, School of Engineering & Applied Sciences, Nile University, Smart Village, Cairo, Egypt 3 Socio-Economic Division, Desert Research Center, El-Matariya, P. O. Box 11753, Cairo, Egypt Received 20 March 2011; accepted 10 September 2011 DOI 10.1002/app.35628 Published online 27 December 2011 in Wiley Online Library (wileyonlinelibrary.com). ABSTRACT: Composite beads composed of chitosan (CS) with different carbon nanotubes (CNTs) were pre- pared by the incorporation of single-walled carbon nano- tubes (SWCNTs), multiwalled carbon nanotubes (MWCNTs), and carboxylic multiwalled carbon nanotubes (MWCNT-COOHs). A protected crosslinking method was used for the preparation of the CS/CNTs beads by the reaction of the beads with Hg(II) as the protector. Scan- ning electron microscopy, Fourier transform infrared spec- troscopy, and thermogravimetric analysis were used to characterize the prepared beads. The adsorption perform- ance of the prepared beads was investigated for the re- moval of Hg(II). The results show that beads prepared by the protected crosslinking technique removed 2.5 times more Hg(II) from solution than beads prepared by normal crosslinking. The maximum Hg(II) removal values were 148.7, 183.2, 167.5, and 172.7 mg/g by CS, MWCNT- COOH-impregnated CS beads, MWCNT-impregnated CS beads, and SWCNT-impregnated CS composite beads, respectively. The optimum removal conditions were pH ¼ 4, contact time ¼ 40 min, and temperature ¼ 70  C. The equilibrium adsorption isotherm data of the beads exhib- ited a better fit to the Langmuir isotherm model. The reus- ability of Hg(II) sorption by the prepared beads was investigated to evaluate their repeated availability per- formance in water treatment. Quantitative removal of mer- cury from industrial wastes was demonstrated. A statistical analysis of the replacement cost of these sorbents revealed that SWCNTs, MWCNTs, and MWCNT-COOH could possibly be cost-effective sorbents in water treat- ment, regardless of their high unit cost at this time. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 125: E93–E101, 2012 Key words: adsorption; blends; crosslinking; nanotechnology INTRODUCTION The pollution of water resources due to the indis- criminate disposal of metal ions has been causing worldwide concern. Wastewater from many indus- tries, such as the metallurgical, tannery, chemical manufacturing, mining, and battery manufacturing industries, contains one or more toxic metal ions. 1 Mercury is one of the common pollutants of water; it results from the burning of coal by power plants and the inappropriate disposal of batteries, paints, lights, and industrial byproducts. 2 Mercury poison- ing remains an infrequently considered clinical syn- drome, even though mercury is the second most common cause of heavy-metal poisoning. 3,4 Mercury poisoning is becoming more important because of the extensive contamination of water and fish and the increasing consumption of fish in the human diet. 5 Mercury is cytotoxic, exerting its effect by depleting thiol reserves in the mitochondria, which results in cell death. It is extremely neurotoxic and leads to dizziness, irritability, tremors, depression, and memory loss. 6 The removal of metal ions, especially mercury, from wastewaters before they are released into the environment has become a must because there is the possibility of the entry of toxic metal ions into the food chain through waste discharge into water bodies. There are many conventional methods that are being used to remove metal ions, including oxida- tion, reduction, precipitation, membrane filtration, ion exchange, and adsorption. Nowadays, adsorption has been recognized as the most popular treatment pro- cess for the removal of metal ions from aqueous solu- tion because of its simplicity, high efficiency, easy recovery, and reusability of the adsorbent. 7,8 Carbon nanotubes (CNTs), a fascinating new member of the carbon family, have attracted strong Correspondence to: H. A. Shawky (shawkydrc@hotmail. com). Journal of Applied Polymer Science, Vol. 125, E93–E101 (2012) V C 2011 Wiley Periodicals, Inc.