Chitosan/CNTs green nanocomposite membrane: Synthesis, swelling and polyaromatic hydrocarbons removal Saira Bibi a,b , Tariq Yasin a, ⁎, Safia Hassan a , Muhammad Riaz c , Mohsan Nawaz b a Pakistan Institute of Engineering and Applied Sciences, Islamabad, Pakistan b Department of Chemistry, Hazara University, Mansehra, Pakistan c Chemistry Division, PINSTECH, Islamabad, Pakistan abstract article info Article history: Received 11 July 2014 Received in revised form 6 September 2014 Accepted 21 October 2014 Available online 23 October 2014 Keywords: Chitosan Carbon nanotubes Radiation Adsorption Polyaromatic hydrocarbons Carbon nanotubes (CNTs) were irradiated in air at 100 kGy under gamma radiations. The Raman spectroscopy of γ-treated CNTs showed distinctive changes in the absorption bands. The CNTs were mixed with blend of chitosan (Cs)/poly (vinyl alcohol) (PVA) and crosslinked with silane. The chemical reactions between the components af- fected the position and intensities of the infrared bands. Scanning electron micrograph of Cs/CNTs nanocompos- ite membrane showed the homogeneous dispersion of CNTs in the polymer matrix. The addition of CNTs lowered its swelling in water. Naphthalene (NAPH) was selected as a model compound and its removal was studied using HPLC technique. This membrane showed fast uptake of NAPH and 87% was removed from water within 30 min. The NAPH loaded membrane showed strong chemical interactions and cannot be desorbed. The fast uptake of PAHs and the green nature of this membrane made them suitable candidates for clean-up purposes. © 2014 Elsevier B.V. All rights reserved. 1. Introduction A large number of hydrophobic organic compounds such as polyaromatic hydrocarbons (PAHs) are considered as toxic and hazard- ous pollutants. Environment protection agency has classified PAHs among the priority pollutants due to their potential mutagenic, terato- genic and carcinogenic effects on animals [1,2]. Therefore, it is very im- portant to remove these compounds from environment and different methods were used for clean-up purposes [3]. Adsorption process con- taining appropriate adsorbent is an easy and effective process used in many applications. Many natural and synthetic polymers are used as ad- sorbent. Chitosan, a natural polysaccharide has also been used as adsor- bent material for the removal of toxic metals, dyes and organic pollutants etc. [4–6]. Different modifications of chitosan were made for specific applications which include: blending it with other polymers, crosslinking, grafting of chitosan on inorganic support, functionalization and addition of nanofillers [7–10]. Atif et al. showed that the addition of PVA and its crosslinking with silanes improved its stability and mechan- ical strength [9]. Recently, CNTs have gained great importance due to their exception- al properties such as: large specific area, highly porous, hollow struc- ture, good antifouling, reinforcing properties, biocompatibility and biodegradability [11,12]. They are excellent additives and are being used to modify the polymer properties [13]. The main issue is their uni- form dispersion in polymer matrix that presents a major impediment to its effective utilization. They tend to bundle up and form agglomerates due to the presence of Van der Waal interactions [14]. Different methods/treatments were used to overcome these problems [15]. The most common one is the chemical modifications of the graphene sur- face of CNTs by oxidation in a concentrated acidic media. This treatment affected the mechanical and electrical performance of the CNTs. The modification of CNTs with high energy radiations is a fast and more ef- fective method [16]. Radiation has many advantages such as: easy con- trol over its modification, low reaction temperatures, chemical free solvent and time saving [17–19]. This study aims at developing rapid performance Cs/CNTs mem- brane by incorporating γ-treated CNTs for the adsorption of PAHs from water. CNTs were modified using gamma radiations. Naphtha- lene (NAPH) is taken as a model compound and its removal was studied using high performance liquid chromatography (HPLC) technique. 2. Experimental 2.1. Materials Chitosan (C3646 degree of deacetylation ca 75%, viscosity N 200 cP), PVA (Mw: 146,000–186,000), poly (vinyl pyrrolidone) (PVP) tetraethyl orthosilicate, 98% (TEOS), triethoxy-vinylsilan, 97% (VTES), potassium Materials Science and Engineering C 46 (2015) 359–365 ⁎ Corresponding author. E-mail address: yasintariq@yahoo.com (T. Yasin). http://dx.doi.org/10.1016/j.msec.2014.10.057 0928-4931/© 2014 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Materials Science and Engineering C journal homepage: www.elsevier.com/locate/msec