title: Enhanced removal of nitrate from water using amine-grafted agricultural wastes.
abstract: Adsorption using low-cost adsorbents is a favourable water treatment method for the removal of water contaminants. In this study the enhanced removal of nitrate, a contaminant at elevated concentration affecting human health and causing eutrophication of water, was tested using chemically modified agricultural wastes as adsorbents. Batch and fixed-bed adsorption studies were performed on corn cob and coconut copra that were surface modified by amine-grafting to increase the surface positive charges. The Langmuir nitrate adsorption capacities (mgN/g) were 49.9 and 59.0 for the amine-grafted (AG) corn cob and coconut copra, respectively at pH6.5 and ionic strength 1×10(-3)M NaCl. These values are higher than those of many commercially available anion exchange resins. Fixed-bed (15-cm height) adsorption capacities (mgN/g) calculated from the breakthrough curves were 15.3 and 18.6 for AG corn cob and AG coconut copra, respectively, for an influent nitrate concentration 20mg N/L at a flow velocity 5m/h. Nitrate adsorption decreased in the presence of sulphate, phosphate and chloride, with sulphate being the most competitive anion. The Thomas model fitted well to the fixed-bed adsorption data from four repeated adsorption/desorption cycles. Plug-flow model fitted well to the data from only the first cycle.
authors.affiliation: Faculty of Engineering, University of Technology Sydney (UTS), P.O. Box 123, Broadway, NSW 2007, Australia.
authors.forename: Mahatheva
authors.initials: M
authors.lastname: Kalaruban
authors.affiliation: Faculty of Engineering, University of Technology Sydney (UTS), P.O. Box 123, Broadway, NSW 2007, Australia.
authors.forename: Paripurnanda
authors.initials: P
authors.lastname: Loganathan
authors.affiliation: Faculty of Engineering, University of Technology Sydney (UTS), P.O. Box 123, Broadway, NSW 2007, Australia; Department of Polymer Science and Engineering, Sunchon National University, 255 Jungang-ro, Suncheon, Jeollanam-do, Republic of Korea.
authors.forename: W G
authors.initials: WG
authors.lastname: Shim
authors.affiliation: Faculty of Engineering, University of Technology Sydney (UTS), P.O. Box 123, Broadway, NSW 2007, Australia.
authors.forename: Jaya
authors.initials: J
authors.lastname: Kandasamy
authors.affiliation: Faculty of Engineering, University of Technology Sydney (UTS), P.O. Box 123, Broadway, NSW 2007, Australia.
authors.forename: H H
authors.initials: HH
authors.lastname: Ngo
authors.affiliation: Faculty of Engineering, University of Technology Sydney (UTS), P.O. Box 123, Broadway, NSW 2007, Australia. Electronic address: s.vigneswaran@uts.edu.au.
authors.forename: Saravanamuthu
authors.initials: S
authors.lastname: Vigneswaran
mesh_terms: D000327:Adsorption; D000383:Agriculture; D004785:Environmental Pollutants / Q000032:analysis* / Q000737:chemistry; D009566:Nitrates / Q000032:analysis* / Q000737:chemistry; D018505:Waste Management / Q000379:methods; D018508:Water Purification / Q000379:methods*; D060753:Water Quality; D003313:Zea mays
chemical_list: D004785:Environmental Pollutants; D009566:Nitrates
keywords: Adsorption models; Agricultural wastes adsorbents; Nitrate; Water treatment