Styrene N-vinylpyrrolidone metal-nanocomposites as antibacterial coatings against Sulfate Reducing Bacteria M. Fathy a , A. Badawi b , A.M. Mazrouaa c , N.A. Mansour c , E.A. Ghazy d , M.Z. Elsabee e, ⁎ a Analysis and Evaluation Department, Egyptian Petroleum Research Institute (EPRI), 1 Ahmed El-Zomor St., Nasr City, 11727 Cairo, Egypt b Petrochemical Department, Surfactant Laboratory, Egyptian Petroleum Research Institute (EPRI), 1 Ahmed El-Zomor St., Nasr City, 11727 Cairo, Egypt c Petrochemical Department, Polymer Laboratory, Egyptian Petroleum Research Institute (EPRI), 1 Ahmed El-Zomor St., Nasr City, 11727 Cairo, Egypt d Department of Microbial Biotechnology, Genetic Engineering Division National Research Center, Dokki, Cairo, Egypt e Department of Chemistry, Faculty of Science, Cairo University, 12613 Giza, Egypt abstract article info Article history: Received 25 September 2012 Received in revised form 9 May 2013 Accepted 24 May 2013 Available online 2 June 2013 Keywords: Styrene/vinylpyrrolidone copolymer Nanometal oxide Nanocomposite SRB Biocidal activity Copolymer of styrene, and vinylpyrrolidone was prepared by various techniques. Different nanometals and nanometal oxides were added into the copolymer as antimicrobial agents against Sulfate Reducing Bacteria (SRB). The nanocomposite chemical structure was confirmed by using FTIR, 1 H NMR spectroscopy and thermogravimetric analysis (TGA). The biocidal action of these nanocomposites against the SRB was detected using sulfide determination method in Postgate medium B. The data indicated that the nanocomposites had an inhibitory effect on the growth of SRB and reduced the bacterial corrosion rate of mild steel coupons. The prepared nanocomposites have high inhibition efficiency when applied as coatings and show less efficiency when applied as solids or solution into SRB medium. The copolymer and its nanocomposites effectively re- duced the total corrosion rate as determined by total weight loss method. © 2013 Elsevier B.V. All rights reserved. 1. Introduction Iron materials are corroded in aqueous environments, not only by purely chemical or electrochemical reactions but also by microorgan- isms or the products of their metabolic activities including enzymes, organic and inorganic acids as well as volatile compounds such as hy- drogen sulfide. This process is termed Microbiologically Induced Cor- rosion (MIC) [1]. The direct cost of the MIC is estimated to be $30–50 billion per year around the world. In the UK, it was suggested that 50% of corro- sion failures in pipelines involved MIC [2] and the replacement costs for bio-corroded gas pipes were recently reported to be 250 million per annum [3]. Also, the American industries spend $1.2 billion annu- ally on biocidal chemicals to fight MIC. The MIC may account for 15 to 30% of corrosion related pipeline failures in the natural gas industry as a whole. The petroleum industries in Egypt suffer from MIC. It was estimated that one company (Gulf Suez Petroleum Company, GUPCO) spends more than one million $/year to combat MIC [4]. Bacterial activity, mainly Sulfate Reducing Bacteria (SRB) activity, is responsible for over 75% of the corrosion in productive oil wells and for more than 50% of the buried pipeline and cable failure. It is also deem an agent for extensive corrosion of drilling and pumping machinery and storage tanks [5]. The Sulfate Reducing Bacteria (SRB) represent a large group of anaer- obic (oxygen free) organisms which play an important role in many bio- geochemical processes. They are widely distributed in the environment particularly in petroleum reservoirs and oil production facilities [6]. The two most common species of these bacteria are Desulfovibrio desulfuricans and Desulfotomaculum nigrificans. These organisms favor an anaerobic environment. The presence of SRB in oil environments was readily recognized as responsible for the production of hydrogen sulfide, which is a toxic and corrosive gas responsible for reservoir souring (increase sulfur content) [7] and a variety of other environmental problems which have economic consequences. SRB decreases the quality and value of oil, and natural gas. It causes corrosion of metal surfaces, and con- tributes to plugging of reservoirs due to the precipitation of metal sul- fides in the fluid flow paths [8–10]. As the detrimental effects of SRB in the oil industry are significant, they have been the most commonly studied group in that realm [1]. Considerable efforts have been directed toward controlling SRB growth and corrosion inhibition induced by its activity. Corrosion in- hibition is a process to slowdown the corrosion reaction by adding substances in small amounts, to decrease the rate of attack by these bacteria on a metal [11]. A number of methods for controlling SRB sul- fide production in different oil and gas facilities have been utilized using the biocides [12]. Although biocide treatments are widely used to decrease biofoul- ing and MIC in steel pipes and in closed systems, the results are far Materials Science and Engineering C 33 (2013) 4063–4070 ⁎ Corresponding author. Tel.: +20 2 26352316, +20 1006680474(Mobile). E-mail address: mzelsabee@yahoo.com (M.Z. Elsabee). 0928-4931/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.msec.2013.05.048 Contents lists available at ScienceDirect Materials Science and Engineering C journal homepage: www.elsevier.com/locate/msec