Utilization of corn fibers and luffa peels for extraction of pollutants from water Ramakrishna Mallampati a , Kuang Shing Tan b , Suresh Valiyaveettil a, b, * a NUS Environmental Research Institute National University of Singapore,117411, Singapore b Department of Chemistry, National University of Singapore, 3 Science Drive 3,117543, Singapore article info Article history: Received 15 November 2014 Received in revised form 26 March 2015 Accepted 26 March 2015 Available online 27 April 2015 Keywords: Adsorption Luffa peels Corn fibers Dyes Metal ions abstract Corn fibers and luffa peels were evaluated for removing toxic heavy metal ions and dissolved organic dyes from water. Fresh peels were pretreated to remove all soluble components before using them for extraction studies. Presence of eOH and eCO 2 H functional groups on the surface of the peels and rough morphologies were characterized using Fourier transform infrared spectroscopy and scanning electron microscopy investigations, respectively. Corn fibers and luffa peels showed maximum extraction effi- ciencies within the pH range of 4e10 and adsorption reached a steady state within 2e3 h. Prewashed corn fibers and luffa peals extracted 159 mg g 1 and 90 mg g 1 of alcian blue, 70 mg g 1 and 124 mg g 1 of methylene blue, 50 mg g 1 and 108 mg g 1 of neutral red as well as 35 mg g 1 and 40 mg g 1 of coomassie brilliant blue from water, respectively. Both materials did not show significant extraction affinity towards heavy metal ions such as Pb 2þ (1 mg g 1 ), Ni 2þ (4 mg g 1 for corn fiber and 12 mg g 1 for luffa peels), and chromate (3 mg g 1 for corn fibers and 6 mg g 1 for luffa peels) ions from water. The Langmuir and Freundlich isotherms were used to understand the adsorption process on the surface of the adsorbents. Langmuir isotherm model yielded the best fit for the data obtained in the study, indi- cating a monolayer adsorption of pollutants on the adsorbent surface. Both adsorbents can be regen- erated at acidic pH and could be reused for up to five cycles without significant loss of efficiency. Our experimental results suggest that both natural materials are effective towards removing dissolved dyes from water. © 2015 Elsevier Ltd. All rights reserved. Introduction Pollutants such as heavy metal ions and dissolved organic compounds are highly toxic to living systems (Veglio and Beolchini, 1997; Ghimire et al., 2003). Such pollutants often get into local water supply chain from industrial effluents and agricultural usage and cause health hazards to living organisms (Vandevivere et al., 1998; O'Neill et al., 1999). Water purification methods such as chemical coagulation, precipitation, flocculation, activated sludge bioreactors, membrane separation and ion exchange methods have been developed to remove pollutants from water (Nawar and Doma, 1989; Veglio and Beolchini, 1997; Ghimire et al., 2003; Kumar and Bandyopadhyay, 2006b). But no single technique or ideal material exists for the removal of all pollutants from water. Biosorbents are considered as renewable adsorbents and show potential application towards removal of a range of pollutants from water. Banana peel (Hossain et al., 2012), orange peel (Nawar and Doma, 1989; Ghimire et al., 2003; Biswas et al., 2008), grape waste, rice husk (Kumar and Bandyopadhyay, 2006a,b), tea waste (Malkoc and Nuhoglu, 2005, 2007), maize corn cob, sugarcane bagasse (Garg et al., 2007) and pine bark (Al-Asheh et al., 2000) were proposed as potential adsorbents for water purification. However, many of these studies are limited to specific pollutants and not applied for a range of toxic pollutants, which includes metal ions, dissolved organics or other pollutants. The main dis- advantages for bioadsorbents are low stability and release of sol- uble organic compounds into water during treatment which limits their use in large scale applications. This warrants the development of efficient adsorbents that will not contaminate water by releasing soluble components during the purification. Adsorption of pollut- ants on the surface of biosorbents involves one or more factors such as ion exchange, complexation and electrostatic interactions (Biswas et al., 2008; Gadd, 2009). Plant based materials consisting * Corresponding author. Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore. E-mail address: chmsv@nus.edu.sg (S. Valiyaveettil). Contents lists available at ScienceDirect International Biodeterioration & Biodegradation journal homepage: www.elsevier.com/locate/ibiod http://dx.doi.org/10.1016/j.ibiod.2015.03.027 0964-8305/© 2015 Elsevier Ltd. All rights reserved. International Biodeterioration & Biodegradation 103 (2015) 8e15