Effect of silver loaded sodium zirconium phosphate (nanoAgZ) nanoparticles incorporation on PES membrane performance Jian Huang a , Gangasalam Arthanareeswaran b , Kaisong Zhang a, ⁎ a Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China b Membrane Research Laboratory, Department of Chemical Engineering, National Institute of Technology, Tiruchirappalli, 620015, India abstract article info Article history: Received 11 August 2011 Received in revised form 26 September 2011 Accepted 27 September 2011 Available online 22 October 2011 Keywords: PES membrane NanoAgZ Antifouling Anti-biofouling Polyethersulfone (PES) based ultrafiltration membranes were fabricated via phase inversion by adding silver- loaded sodium zirconium phosphate nanoparticles (nanoAgZ) in PES casting solutions. The effect of nanoAgZ concentration on the membrane performance, i.e., morphology, hydrophilicity, thermal stability, permeation and antifouling properties was investigated. The results of thermal gravitational analysis (TGA) showed that the thermal stability of the hybrid membrane had been improved by the addition of nanoAgZ particles. Con- tact angle results indicated that the hydrophilicity of the modified membranes was enhanced. The contact angle of the membrane decreased from 71.5° to 52.6° with the increase of the nanoparticle content in the casting solution. Permeation experiment results showed that the modified PES membranes demonstrate bet- ter separation performance over the pure PES membrane. The pure water flux of PES membrane increased from 82.1 L/m 2 h to 100.6 L/m 2 h with the addition of the nanoparticles. Most importantly, the incorporation of the nanoAgZ particles enhanced the BSA fouling resistance and also the anti-biofouling performance of the membrane. © 2011 Elsevier B.V. All rights reserved. 1. Introduction As the increase of demand for water and wastewater treatment, membrane filtration process has been increasingly used to produce fresh water in wastewater reuse. However, biofouling is recognized as the main problem in the application of membrane filtration tech- nologies, especially in the treatment of wastewater with relative high biological components. For membrane systems, biofouling has severe impacts on the membrane performance, such as decreasing the permeate flux, increasing energy costs and shorting the mem- brane lifetime [1–3]. Unlike other kinds of fouling, bio-fouling is much more difficult to be cleaned by pretreatment of the feed due to the self-replicating nature of biofouling organisms. Even 99.99% removal of bacteria from a feed stream will leave some cells alive and can grow and multiply rapidly [4].The main strategies to control bio-fouling including “anti-adhesion” approaches to reduce initial adsorption of bacteria and “antimicrobial” approaches to suppress the activity of attached organisms. It has often been observed that membranes with a hydrophilic surface are much less likely to be attached with bacteria than with hydrophobic surfaces. However, most of the industrial polymeric membranes materials are usually hydrophobic. As a result, many studies focus on modifying the con- ventional membranes to increase their hydrophilicity so as to reduce membrane biofouling [5–6] or on exploring new membrane materials with reduced bacterial affinity to prevent or slow the initial organism attachment [7]. For “antimicrobial” approaches, some biocides can be directly incorporated into the membrane which aims at effectively killing bacteria that have already attached on the membrane surface and thus preventing their growth [8]. Biocides such as heavy metals, including copper [9] or silver, have been demonstrated for their effec- tiveness in anti-bacterial performance. Among them, silver is of special interest because of its high toxicity toward many types of bacteria, but low toxicity for humans and animals [10–11]. Silver nanoparticles have been incorporated to cellulose acetate [12], polyimide [13], polyamide [14] and polyethersulfone [15–16]. However, most of the works conducted on incorporating silver into polymers reported leaching problems due to the poor compati- bility of the silver and the polymer [12, 17]. To overcome such losses it is necessary to design a carrier to release the silver slowly. For silver loaded inorganic antibacterial materials, the release time of Ag can be delayed for a long time so that silver-supported materials have great potential for antibacterial applications [18]. So far, several kinds of sil- ver carried antibacterial agents using different inorganic carriers, such as zeolite [19], mesoporous silica [20], titanium dioxide [21], and carbon fiber [22] have been developed. Silver carried sodium zir- conium phosphate has been developed as various commercial prod- ucts due to its excellent color stability [23]. PES was an extensively Desalination 285 (2012) 100–107 ⁎ Corresponding author. Tel.: + 86 592 6190782; fax: + 86 592 6190977. E-mail address: kszhang@iue.ac.cn (K.S. Zhang). 0011-9164/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.desal.2011.09.040 Contents lists available at SciVerse ScienceDirect Desalination journal homepage: www.elsevier.com/locate/desal