Kinetics of the remediation of Arsenic-contaminated groundwater using nanoscale magnetite particles
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1045-V03-08
Kinetics of the remediation of Arsenic-contaminated groundwater using nanoscale magnetite particles Parameswar Hari1, Aaron Isley2, Greg Medders2, and Gordon Purser2 1 Physics and Engineering Physics, University of Tulsa, 800 S. Tucker Avenue, L-165, Keplinger Hall, Physics Department, Tulsa, OK, 74104-3189 2 Chemistry Department, University of Tulsa, Tulsa, OK, 74104 ABSTRACT Arsenate species are toxic compounds widely found as contaminants in industrial and metallurgical environments. Environmental health problems related to industrial waste streams and related drinking water contaminations commonly occur. Around the world, from Bangladeshi water wells to metal plating sites in Oklahoma, toxic levels of arsenic (As) leach into potable water. This paper describes a flow loop system that utilizes magnetite (Fe3O4) particles for the removal of these toxic metals. Nanoscale magnetite particles are used as they have an extremely high surface area which allows for the rapid removal of toxic species. Perhaps even more importantly, magnetite has a unique advantage in that it can easily be removed and concentrated using inexpensive low field magnetic (125 mT) separation techniques. In this study the results of treating arsenic-contaminated water with 50 nm and 26 nm nanoparticles are presented. INTRODUCTION Metal plating sites having toxic levels of arsenic in water systems pose a significant problem worldwide. However, as discussed in a recent paper in the American Chemical Society’s Chemical and Engineering News, arsenic compounds in drinking water can be successfully removed to EPA accepted levels by utilizing separation techniques based on simple technology employing a low field magnet and magnetite particles [1]. Recently, a research group at Rice University has been able to generate and separate dispersed nanocrystalline magnetite particles using low magnetic fields [2]. Previously reported studies have employed magnetic particles dispersed in stagnant water [3]. In order to remove arsenic efficiently and quickly and attain arsenic level at or below the EPA accepted standard of 10 micrograms per liter, a continuous flow loop system has been built and its effectiveness studied. The flow loop system consists of a pump, low field magnets for magnetic filtration of the nanoscale iron particles, and a reservoir for dispersing the nanoparticles in arsenic-contaminated water. This paper describes the results of our recent studies using the flow loop system and magnetic filtration. EXPERIMENT Experiments were performed by adding nanoscale magnetite particles (26 nm -50 nm) to arseniccontaminated water samples. The particles were dispersed via ultrasonic mixing for 10 minutes. The mixture was allowed to stand for a period of time and then pumped using a paristaltic pump through a glass column positioned in the magnetic field of four high quality neodynium-ironboron magnets. The main components of the flow loop system are illustrated in Figure 1. The main objectives of flow-loop studies were: 1) to demonstrate the
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