Development of flow-through chemical sensors for process control

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The purpose of this project is to develop a potentiometric- and a spectrophotometric sensor systems for process control of chemical industry. The sensor system is flow-though type sensors for pH,metal ions and redox species sensor based on the reaction with a pH,metal and redox potential buffer solution. Followings are the summary of results of this project.(1) Potentiometric sensorsA flow system for determination of acids and bases was designed by using a pH buffer solution prepared from polyacrylic acid or polyethyleneimine, a dialysis unit and a flow-through type pH glass electrode detector. The sensitivity of the detector to acids and bases was found to depend on the concentration of polyelectrolytes and a sample volume injected into the flow system. Concentrated hydrochloric acid and sodium hydroxide solution up to about 10 M could be successfully determined by the developed sensor system. A flow system for determination of heavy metal ions was also designed by using a cupper (II) … More ion buffer solution prepared by polyacrylic acid or polyethyleneimne and cupper (II), the dialysis unit and a flow-through thpe cupper (II) ion selective electrode detector. The sensor was found to respond to many metal ions such as zinc, nickel, cobalt and lead ions. A flow-through-type redox electrode was developed by using an Fe (II) and Fe (III) form polystirenesuflonic acid solution as an inner solution of a redox electrode. The inner solution was covered with a dialysis membrane. The potential change of the inner electrode is the measure of the concentration of redox species to be determined. Hydrogen peroxide and ascorbic acid were successfully determined by the developed sensor.(2) Spectrophotometric sensorsA flow system for determination of acids, bases and metal ions was designed by using a pH buffer solution and a flow-through cell packed with controlled pored glass beads immobilized with a pH indicator, fluorescein. Fluorescence intensity was found to be proportional to the concentration of hydrochloric acid and sodium hydroxide. A flow system for determination of Mg^<2+> and La^<3+> was designed by using a NTA solution or EDTA solution and a flow-through cell prepared by a tubular type anion exchange membrane immobilized with Calmagite or ArsenazoIII.A flow through cell immobilized Calmagite in to plasticized poly (vinyl chloride) membrane was also prepared. The detector signal from the flow cell was proportional to the concentration of Mg^<2+> and La^<3+> and the response was reversible. Less