Removal of Copper and Zinc from Ground Water by Granular Zero-Valent Iron: A Study of Kineticsby Tom M. Statham, Kathryn A. Mumford, Geoffrey W. Stevens

Separation Science and Technology

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Removal of copper and zinc from ground water by granular zero-valent iron: a study of kinetics

Tom M. Stathama, Kathryn A. Mumforda & Geoffrey W. Stevensa a Particulate Fluids Processing Centre, Department of Chemical and Biomolecular

Engineering, University of Melbourne, Australia

Accepted author version posted online: 08 May 2015.

To cite this article: Tom M. Statham, Kathryn A. Mumford & Geoffrey W. Stevens (2015): Removal of copper and zinc from ground water by granular zero-valent iron: a study of kinetics, Separation Science and Technology, DOI: 10.1080/01496395.2015.1014052

To link to this article: http://dx.doi.org/10.1080/01496395.2015.1014052

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Removal of copper and zinc from ground water by granular zero-valent iron: a study of kinetics

Tom M. Statham, Kathryn A. Mumford*, Geoffrey W. Stevens

Particulate Fluids Processing Centre, Department of Chemical and Biomolecular Engineering,

University of Melbourne, Australia * Corresponding author tel.: +613 8344 0048; fax: +613 8344 4153 mumfordk@unimelb.edu.au

Abstract

Three different granular zero-valent iron (ZVI) sources are assessed for the removal of Cu2+ and

Zn2+ ions from aqueous solutions. For initial heavy metal concentrations of 50 µM the observed kinetics could be modelled via first order reaction rates. Differences in the observed kinetic rate of copper and zinc removal for different ZVI sources could not be explained by geometric or nitrogen based adsorption surface areas. Results obtained via varying both temperature and shaker rate indicate that in an environment which contains dissolved oxygen, ion diffusion and hence water flow rate will control the kinetics of copper and zinc removal by granular ZVI.

Keywords heavy metal; low temperature; mass transfer; PRB; Antarctic remediation 1. Introduction

Since the mid 1980s there has been rapid development and deployment in the use of zero-valent iron (ZVI) for environmental remediation [1, 2]. ZVI has been shown to successfully treat water

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Ac ce pte d M an us cri pt 2 contaminated with heavy metals such as arsenic, chromium, copper, manganese, uranium and zinc [3-6]. The contaminants removed from water by ZVI has been expanded to a broader range of pollutants, including freons, radionuclides, pesticides, phosphates, nutrients, explosives, viruses and bacteria [7-10]. A major focus of this research has been the development of ZVI as a media for the treatment of contaminant plumes by permeable reactive barriers (PRBs) [11].

The majority of commercial granular ZVI is produced from industrial scrap iron and steel. The presence of alloying elements and impurities, whether the material is cast, forged, wrought or welded, kiln firing atmosphere, cooling history and milling procedures can all affect the iron morphology and oxide coating on a micro- or macro-scale and hence the corrosion and contaminant removal rates (reactivity) [12]. Most commercial suppliers reprocess a feedstock by combining numerous sources of scrap iron and steel which are subsequently heated in a kiln, cooled, milled and sorted to specific grain size [13]. The resulting contaminant removal rates of the ZVI can be highly variable [12].

The rates of organic carbon degradation and metal removal within ZVI PRBs are generally accepted to be dependent on the surface area of the specific ZVI manufacturing/reprocessing process [13]. However, when comparing different ZVI sources with similar particle size distributions and surface areas which have been produced using different methods, differences in the reactivity and contaminant treatment kinetics have been documented by several research groups [14-18]. Both Pierce et al. and Noubactep have assessed the reactivity of different ZVI sources [12, 19]. The degradation of chlorinated aliphatic hydrocarbons by numerous sources of micro-scale ZVI has also been assessed [18]. Trends with varying carbon and oxygen content