Sensors for Continuous Monitoring of Toxic Ions,Nutrients,and Dissolved Gases in Water,

摘要

Ion-selective electrodes and a new type of dissolved gas sensor based on piezoelectric crystals were assessed for use in continuous monitoring of water quality. Relevant stream and effluent water quality standards were reviewed in order to define the constraints on the use of these sensors. The use of sensors in continuous monitoring programs in the United States and other countries was also examined and reviewed. The state-of-the-art of ion-selective electrodes for toxic ions,nutrients and dissolved gases in water was reviewed. A tabular summary of electrode characteristics and an extensive bibliography were compiled. Recommendations for the use of these sensors were made with consideration of the practical problems encountered in continuous monitoring. A dissolved gas sensor for carbon dioxide utilizing a coated piezoelectric crystal was fabricated and evaluated. Didodecylamine and dioctadecylamine were useful coating materials but were also sensitive to water vapor and sulfur dioxide. A probe was designed with the crystal isolated from the aqueous sample by a film of polyvinyl chloride,cast Teflon or by a microporous Teflon filter.