Title: Adsorption isotherm and kinetics of paraquat removal using activated carbon/iron oxide composite material

Authors: Jirapat Ananpattarachai; Pattra Aphaiphak; Roongkarn Ard-ong; Puangrat Kajitvichyanukul; Yung-Tse Hung

Addresses: Center of Excellence on Environmental Research and Innovation, Department of Civil Engineering, Faculty of Engineering, Naresuan University, 99 Moo 9 Tambon Tha Pho, Mueang, 65000, Thailand ' Center of Excellence on Environmental Research and Innovation, Department of Civil Engineering, Faculty of Engineering, Naresuan University, 99 Moo 9 Tambon Tha Pho, Mueang, 65000, Thailand ' Center of Excellence on Environmental Research and Innovation, Department of Civil Engineering, Faculty of Engineering, Naresuan University, 99 Moo 9 Tambon Tha Pho, Mueang, 65000, Thailand ' Center of Excellence on Environmental Research and Innovation, Department of Civil Engineering, Faculty of Engineering, Naresuan University, 99 Moo 9 Tambon Tha Pho, Mueang, 65000, Thailand ' Department of Civil and Environmental Engineering, Cleveland State University, Cleveland, Ohio, 44115 USA

Abstract: A composite material between activated carbon (AC) and iron oxide in nanoscale was used to remove paraquat from contaminated water. The surface area of AC/iron oxide nanoparticles was in the range of 754.39 to 775.81 m²/g for the ratio 1:1 to 10:1 AC:iron oxide nanoparticles. The maximum adsorption capacity was found at pH 11. Adsorption of paraquat increases with increase in temperature indicating an endothermic process. Sorption behaviour of paraquat onto AC/iron oxide nanoparticles was evaluated using the Langmuir and Freundlich isotherm. The adsorption behaviour of paraquat was well described by Freundlich isotherm indicated that AC/iron oxide nanoparticles posed heterogeneous surface with heterolayer paraquat coverage on the surface of composite material. First and second order kinetic models were tested. The paraquat adsorption rate fits a pseudo-second-order kinetic model where the rate-limiting step is assumed to be chemical sorption between the adsorbate and adsorbent. The AC/iron oxide nanoparticles can readily be separated from the solution using a permanent magnet.

Keywords: adsorption; activated carbon; iron nanoparticles; nanomaterials; paraquat removal; kinetics; iron oxide; nanocomposites; nanotechnology; water pollution; sorption behaviour; Langmuir and Freundlich isotherm; kinetic modelling.

DOI: 10.1504/IJEWM.2016.078591

International Journal of Environment and Waste Management, 2016 Vol.17 No.3/4, pp.189 - 202

Received: 10 Jun 2015
Accepted: 14 Feb 2016

Published online: 25 Aug 2016 *

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