Author : Mohamed M. Marei
Publisher :
ISBN 13 :
Total Pages : 174 pages
Book Rating : 4.:/5 (926 download)
Book Synopsis Electrochemical and Microfabrication Strategies for Remotely Operated Heavy Metal Sensor Networks for Water Analysis by : Mohamed M. Marei
Download or read book Electrochemical and Microfabrication Strategies for Remotely Operated Heavy Metal Sensor Networks for Water Analysis written by Mohamed M. Marei and published by . This book was released on 2014 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt: Current heavy metal monitoring in water utilizes sophisticated instrumental methods at centralized laboratories. For many applications, a preferable approach is the deployment of remote sensor networks. To this end, electrochemical methods in conjunction with microfabricated sensors potentially offer the required sensitivity and practical advantages including inexpensive sensors, reduced need for manual operation, reduced energy requirements, and also takes advantage of existing technologies such as communications networks for real-time data acquisition. The remote sensor platform developed herein consists of a photo-lithographically patterned gold electrode on SiO2 substrate within a custom stopped-flow thin-layer cell (TLC). Metal concentrations were evaluated by anodic stripping coulometry (ASC), where it was possible to pre-concentrate all dissolved metals from the finite TLC volume in about a minute. Unlike previously reported ASC approaches which rely on either linear sweep voltammetry or chronopotentiometry, the ASC variant described herein utilizes a potential step to simultaneously strip all deposited metals. The use of a double potential step ASC method also allowed in situ blank subtraction without the need for a separate blank solution. To achieve selectivity, several deposition potentials are used to pre-concentrate only those metals which can be reduced at a given potential. This method is demonstrated to be capable of measuring 500 ppb As(III) to better than 10% error even in the presence of high interferent levels (1.3 ppm Cu2+, 500 ppb Cd2+, 500 ppb Pb2+, and 5 ppm Zn2+). Similar performance was possible for As(III) spiked Ohio River water after pH adjustment. For more negatively reduced metals, dissolved oxygen (DO) reduction interferes with stripping analysis. An indirect in-line electrochemical DO removal device (EDOR), utilizing a silver cathode to reduce DO in a fluidically isolated chamber from the sample stream, was therefore developed. This device is capable of 98 % DO removal at flow rates approaching 50 μL/min with power consumption as low as 165 mW hr L-1. Besides our specific stripping application, this device is well suited for Lab on Chip (LOC) applications where miniaturized DO removal and/or regulation are desirable.
