ORIGINAL PAPER Chemical and biological treatment of waste water with a novel silver/ordered mesoporous alumina nanocomposite B. Yahyaei • S. Azizian • A. Mohammadzadeh • M. Pajohi-Alamoti Received: 29 January 2014 / Accepted: 14 May 2014 Ó Iranian Chemical Society 2014 Abstract One of the serious problems in the present century is chemical and biological pollution of the envi- ronment. Nanocomposites are multiphase solid materials that have been used as adsorbent of pollutants such as dyes, pesticides, anions and etc. in the last decades. In this study, a novel nanocomposite including silver nanoparticles and ordered mesoporous alumina (OMA) has been synthesized and used for the removal of dyes pollutants (methyl orange, bromothymol blue and reactive yellow) from aqueous solution. The characterization of synthesized nanocom- posite has been performed by TEM, N 2 adsorption/ desorption, XRD and energy dispersive X-ray spectroscopy analysis. The adsorption kinetic and equilibrium data have been obtained by UV–vis spectroscopy. The results show that the silver/OMA nanocomposite (Ag/OMA nanocom- posite) is good adsorbent for the removal of anionic dyes from aqueous solution, and also this nanocomposite has a biocidal action against both Gram-negative and Gram- positive bacteria. Keywords Ordered mesoporous alumina  Ag nanoparticles  Rapid adsorption  Adsorption  Antibacterial Introduction The pollution of ground waters by industries is the serious danger for organisms and ecosystems. So the treatment of waste water is necessary for chemical and biological point of view especially for drinking water. The disposal of industries such as textile, plastic, paper and food industries contains plenty of aromatic organic colorants. Various methods such as ozonation [1, 2], flocculation [3], adsorption [4] and decolorization [5, 6] have been used to treat waste water. Among these methods, adsorption is the most effective and low-cost method. Due to the multifunctional properties of nanocompos- ites, these materials gain the researchers attention, recently. Different nanocomposites were used as adsorbent of dif- ferent types of pollutants. For example, CuFe 2 O 4 /sawdust nano magnetic composite has been used to remove cyanine acid [7]. Malana et al. [8] synthesized polyaniline/ Co 1-x Mg x Fe 2 O 4 nanocomposite (x = 0, 0.5, 1) and used it as the adsorbent of toxic dyes from waste water. Poly-o- toluidine Zr(IV) phosphate was synthesized by Khan et al. [9] and used as pesticide sensitive membrane electrode to remove 2,4,5-trichlorophenoxy acetic acid. Recently, we have shown that ordered mesoporous alumina (OMA) has a high potential for the removal of anionic dye pollutants from aqueous solutions [4] with high rate of adsorption and high adsorption capacity [4]. Since the OMA showed high affinity for dye removal, the syn- thesis of a composite of OMA with bifunctional property (simultaneous dye removal and antibacterial) will be interested from practical point of view, especially for the preparation of drinking water. So in the present study, a novel nanocomposite, consists of OMA and silver nano- particles (Ag NPs), has been synthesized by the combina- tion of two new procedures and used for the removal of dye B. Yahyaei  S. Azizian (&) Department of Physical Chemistry, Faculty of Chemistry, Bu-Ali Sina University, Hamedan, Iran e-mail: sdazizian@yahoo.com; sazizian@basu.ac.ir A. Mohammadzadeh  M. Pajohi-Alamoti Faculty of Paraveterinary Science, Bu-Ali Sina University, Hamedan, Iran 123 J IRAN CHEM SOC DOI 10.1007/s13738-014-0470-2