Nanocomposites Based on Ionene–Bentonite Used to Treat Oily Water Claudia R. E. Mansur, Roberta S. Oliveira, Vanessa Akeda, Yure G. C. Queiro ´s, Luciana S. Spinelli, Elizabete F. Lucas Federal University of Rio de Janeiro, Institute of Macromolecules, Rio de Janeiro, RJ, Brazil Received 30 December 2010; accepted 3 March 2011 DOI 10.1002/app.34477 Published online 26 July 2011 in Wiley Online Library (wileyonlinelibrary.com). ABSTRACT: A large number of processes are used to treat the oily water (oil emulsions in water) produced in the petroleum industry. The treatment strategy depends not only on the strictness of the environmental require- ments in the jurisdiction where the water is discharged, but also on the relative treatment cost. The present study reports tests to assess the effectiveness of removing oil from oily water by adsorption in polymer nanocom- posites. These composites were prepared from ionenes (cationic polyelectrolytes) and sodium bentonite or orga- nophilic bentonite. They were characterized by infrared spectrometry, thermogravimetry, X-ray fluorescence, and X-ray diffraction. The oil-removal effectiveness was eval- uated by mixing nanocomposites and oily water in a shaker bath (batch test). In the tests conducted only with treated sodium bentonite and organophilic bentonite, the oil removal was  70%, whereas the use of polymer nanocomposites raised the adsorption of oil to  90%. These values depended on the mass of material, con- centration of oil in the contaminated water, and the contact time. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 123: 218–226, 2012 Key words: nanocomposites; contaminated water; ionenes INTRODUCTION Clay minerals are generally crystalline hydrous alu- minum phyllosilicates, in some cases containing other elements such as Mg, Fe, Ca, Na, K, and Li. All types of bentonite contain one or more clay min- erals of the smectite group, with montmorillonite as the predominant clay mineral. The clays that contain the highest percentage of montmorillonite are ben- tonite and Fuller’s earth. 1,2 Bentonite has the capacity to exchange the cations naturally present on its internal and external surfa- ces with other cations from aqueous solutions of inorganic and organic salts. This property is mainly responsible for bentonite’s great adsorption power, especially for ions in solution. This property can be used to chemically modify a natural bentonite (NB) to obtain a homoionic bentonite, which is a type that enables exchange of cations with a single cation of a selected inorganic salt. This allows obtaining homo- ionic bentonites of Na, K, Ca, Al, Cr, etc. 3 When NB is in contact with aqueous solutions of quaternary ammonium salts, the exchangeable cati- ons of the clay are replaced by organic cations. The compounds obtained are called organophilic benton- ites or just organobentonites. 4 A new class of composite materials has been developed in recent years by combining inorganic metal alkoxides with polymers or organic materials having low molecular weight (frequently functional- ized). Nanocomposites are defined as a new class of composites, in which at least one dimension of the dispersed particles have nanometric size. 5 Polymer–clay composites are divided into three general classes according to the arrangement of their constituents: conventional composites, in which the clay acts as a conventional filler; intercalated nano- composites, consisting of a regular insertion of the polymer between the clay layers; and delaminated nanocomposites, in which 1-nm thick layers are dis- persed in the matrix to form a monolithic structure in microscale. 6 Various characteristics have been observed for the materials prepared with clays and polymers: various composite species are synthesized by combining a large variety of polymers and host materials 2 ; poly- mers can be accommodated in the interlamellar region with retention of the structural factors and the lamellae; the interlamellar spaces are adaptable to the size of the polymer accommodated; the species aggregated in the interlamellar spaces are Correspondence to: C. R. E. Mansur (celias@ima.ufrj.br). Contract grant sponsors: The Brazilian National Research Council (CNPq), Carlos Chagas Filho Foundation for Research Support (FAPERJ), and the Coordinating Office for Improvement of University Researchers (CAPES). Journal of Applied Polymer Science, Vol. 123, 218–226 (2012) V C 2011 Wiley Periodicals, Inc.