Please cite this article in press as: K. Nath, et al., Performance characteristics of surfactant treated commercial polyamide membrane in the nanofiltration of model solution of reactive yellow 160, J. Water Process Eng. (2015), http://dx.doi.org/10.1016/j.jwpe.2015.02.002 ARTICLE IN PRESS G Model JWPE-115; No. of Pages 11 Journal of Water Process Engineering xxx (2015) xxx.e1–xxx.e11 Contents lists available at ScienceDirect Journal of Water Process Engineering journal h om epage: www.elsevier.com/locate/jwpe Performance characteristics of surfactant treated commercial polyamide membrane in the nanofiltration of model solution of reactive yellow 160 Kaushik Nath ∗ , Tejal M Patel, Haresh K Dave Department of Chemical Engineering, G H Patel College of Engineering & Technology, Vallabh Vidyanagar, Gujarat, India a r t i c l e i n f o Article history: Received 31 October 2014 Received in revised form 11 January 2015 Accepted 9 February 2015 Available online xxx Keywords: Nanofiltration Surfactants Rejection Flux decline a b s t r a c t Top surface modification of commercial PA-NF 150 membrane was carried out by dip-soaking the mem- brane swatches with predetermined concentration of aqueous solutions of sodium dodecyl sulphonate (SDS), cetyltrimethylammonium bromide (CTAB) and Triton X-100 as anionic, cationic and non-ionic sur- factants, respectively. The modified flat sheet membranes were used in the nanofiltration of the Reactive yellow 160 dye waste water in a pilot plant. AFM, FTIR-ATR, and water contact angle measurements were employed to characterize the prepared membranes. Addition of surfactants resulted in membranes with superior dye rejection in comparison to untreated membranes. The percent rejection of dye was in the vicinity of 95% for both CTAB and SDS treated membranes, however the results were different for Triton X-100. CTAB treated PA-NF membrane was observed to have marginally less extent of volumetric flux reduction with time compared to other two surfactant treated membranes. Substantial removal of color was achieved in the nanofiltration experiments with a marked reduction in COD and TDS. The process allowed the production of permeate stream with great reutilization possibilities. © 2015 Published by Elsevier Ltd. 1. Introduction In the past few decades nanofiltration (NF) has evolved from a novel approach into a reliable and commercially attractive standard unit operation for reclamation of waste water. The lower operating pressures compared to reverse osmosis and unique selectivity of the membranes render NF a less energy-intensive and eco-friendly downstream operation for the treatment of effluents containing many different components such as inorganic/organic salts, amino acids and peptides, oligosaccharides, molasses, reactive dyes and so on. It can significantly reduce the levels of dissolved solids, col- ors, organics, hardness, turbidity, divalent and multivalent ions and facilitate the required desalting of permeate streams [1,2]. While NF has a myriad of advantages and benefits to its credit, there is a flip side as well. One of the most important drawbacks of nanofiltration is the decline in flux due to concentration polariza- tion and membrane fouling during the operation. The accumulation of solutes at the membrane surface adversely affects the mem- brane performance. Several studies in recent literature report the effects of the operational parameters including ionic strength, feed ∗ Corresponding author. Tel.: +91 2692231651; fax: +91 2692236896. E-mail address: kaushiknath2003@yahoo.co.in (K. Nath). concentration and feed pressure on flux decline, which typically leads to higher energy requirements and ultimately reducing the lifetime of the membrane [3,4]. However, besides the operational parameters, the mem- brane properties such as the molecular weight cut off (MWCO), pure water permeability, surface charge, surface roughness and membrane hydrophilicity play a paramount role in separation per- formance of the nanofiltration membranes. Solutes are prone to get adsorbed on to the membrane surface through hydropho- bic interaction, hydrogen bonding, van der Waals attraction and electrostatic interaction. Thus, an effective method to reduce membrane fouling aims at the alleviation of these adsorptive interactions and enhancing the repulsive interaction between the foulant molecules and membrane surfaces by modulating the membrane surface properties [5,6]. Membranes with a smooth and hydrophilic surface of similar charge to the foulant seem to pos- sess good anti-fouling property [7,8]. Modified membranes with lower contact angles and lower average surface roughness com- pared to unmodified ones exhibit improved fouling resistances [9]. Both the top layer chemistry and surface coating can strongly affect the properties like surface charge and roughness of a thin film composite membrane, which in turn determines the membrane’s long term performance [10]. Therefore, a good understanding of the impacts of surface-treated membrane properties on the http://dx.doi.org/10.1016/j.jwpe.2015.02.002 2214-7144/© 2015 Published by Elsevier Ltd.