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Bentonite is one of the most commonly used raw materials in the water treatment processes because of its low cost, easily availability and high mechanical and chemical stability. In this study, natural bentonite was modified with a large organic surfactant, which is hexadecyltrimethyl ammonium (HDTMA) bromide. The modified bentonite was called organobentonite. The surface characterization of natural bentonite and HDTMA-bentonite was examined by Fourier transform infrared (FTIR) spectroscopy, X-ray diffractometry (XRD), Brunauer-Emmett-Teller (BET) and thermogravimetric (TG) analysis. FTIR spectroscopy showed the existence of HDTMA functional groups on bentonite surface. XRD results revealed randomly lateral-monolayer arrangements of the intercalated alkylammonium cation. The BET surface area significantly decreased after the modification due to the coverage of the pores of natural bentonite. Differences in the differential thermogravimetric (DTG) peaks for naturaland HDTMA-bentonite were observed and interpreted. HDTMA-bentonite was then tested as an adsorbent for the removal of organic compounds such as dibenzofuran (DBF) from aqueous solutions. The amount of adsorption for HDTMA-bentonite was found to be around 20 times higher than that of natural bentonite in 10 mg dm −3 DBF solution at 20• C. The adsorption kinetics of DBF onto HDTMA-bentonite was also studied at 20, 30 and 40• C and thermodynamic parameters were calculated. The overall adsorption process was exothermic and physical in nature. The results indicate that HDTMA-bentonite is an effective and a low-cost adsorbent for the removal of heterocyclic aromatic compounds such as DBF.

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In this study, poly[(N-vinyl imidazole)-co-(2-dimethylaminoethyl methacrylate)] hydrogels with various mole percentages of monomers were prepared by free radical solution polymerization in aqueous media. N,N'-methylenebisacrylamide and 2,2'-azobisisobutyronitrile were used as cross-linker and initiator, respectively. A Fourier transform infrared spectrophotometer, scanning electron microscope and thermogravimetric analyzer were used for the characterization of the hydrogels. The swelling behavior of the hydrogels in aqueous solution was investigated at pH 6.0 and 25°C. The results showed that swelling characteristics were affected by the 2-dimethylaminoethyl methacrylate content of the copolymeric hydrogel. The swelling degree of hydrogels increased from 4.2 g g -1 to 25.4 g g -1 by increasing the 2-dimethylaminoethyl methacrylate concentration from 0 to 15% with respect to the total moles of the monomers.