In-situ Glycine Sensor Development Based ZnO/Al2
O3
/Cr2
O3
 Nanoparticles

Disinfection by chloramination of water systems is an alternative to chlorination that is frequently used in North America. In such a case, monochloramine is used as the primary source of chlorine for disinfection. Regular monitoring of the residual concentrations of this species is crucial to ensure adequate disinfection. An amperometric sensor for monochloramine would provide fast, reagent free analysis, however the presence of dissolved oxygen in water complicates sensor development. In this work, we have explored the use of in-situ pH control as a method of eliminating oxygen as an interferent by conversion of monochloramine to dichloramine. The electrochemical reduction of dichloramine occurs outside the oxygen reduction window and is therefore not affected by oxygen concentration. Potential sweep methods were used to investigate the conversion of monochloramine to dichloramine at pH 3. The pH control method was used to calibrate monochloramine concentrations between 1 and 10 ppm, with a detection limit of 0.03 ppm. Tests were carried out in high alkalinity samples, wherein it was found that the sensitivity of this method effectively remained unchanged. Monochloramine was also quantified in the presence of common interferents (copper, phosphate and iron) which had no significant impact on the analysis

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Elimination of Oxygen Interference in the Electrochemical Detection of Monochloramine, Using In-Situ pH Control at Interdigitated Electrodes

10.26434/chemrxiv.12743720.v1 ◽

2020 ◽

Author(s):

Ian Seymour ◽

Benjamin O'sullivan ◽

Pierre Lovera ◽

Alan O'Riordan ◽

James Rohan

Keyword(s):

Control Method ◽

Primary Source ◽

Ph Control ◽

Water Systems ◽

Potential Sweep ◽

Sensor Development ◽

Concentration Potential ◽

Copper Phosphate ◽

High Alkalinity

Disinfection by chloramination of water systems is an alternative to chlorination that is frequently used in North America. In such a case, monochloramine is used as the primary source of chlorine for disinfection. Regular monitoring of the residual concentrations of this species is crucial to ensure adequate disinfection. An amperometric sensor for monochloramine would provide fast, reagent free analysis, however the presence of dissolved oxygen in water complicates sensor development. In this work, we have explored the use of in-situ pH control as a method of eliminating oxygen as an interferent by conversion of monochloramine to dichloramine. The electrochemical reduction of dichloramine occurs outside the oxygen reduction window and is therefore not affected by oxygen concentration. Potential sweep methods were used to investigate the conversion of monochloramine to dichloramine at pH 3. The pH control method was used to calibrate monochloramine concentrations between 1 and 10 ppm, with a detection limit of 0.03 ppm. Tests were carried out in high alkalinity samples, wherein it was found that the sensitivity of this method effectively remained unchanged. Monochloramine was also quantified in the presence of common interferents (copper, phosphate and iron) which had no significant impact on the analysis

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Rendez vous with Saturn's rings

International Astronomical Union Colloquium ◽

10.1017/s0252921100101885 ◽

1984 ◽

Vol 75 ◽

pp. 743-759 ◽

Cited By ~ 2

Author(s):

Kerry T. Nock

Keyword(s):

Solar Energy ◽

Electric Propulsion ◽

Power Source ◽

Propulsion System ◽

Low Thrust ◽

Ring Plane ◽

The Earth ◽

Total Impulse ◽

Saturn's Rings

ABSTRACTA mission to rendezvous with the rings of Saturn is studied with regard to science rationale and instrumentation and engineering feasibility and design. Future detailedin situexploration of the rings of Saturn will require spacecraft systems with enormous propulsive capability. NASA is currently studying the critical technologies for just such a system, called Nuclear Electric Propulsion (NEP). Electric propulsion is the only technology which can effectively provide the required total impulse for this demanding mission. Furthermore, the power source must be nuclear because the solar energy reaching Saturn is only 1% of that at the Earth. An important aspect of this mission is the ability of the low thrust propulsion system to continuously boost the spacecraft above the ring plane as it spirals in toward Saturn, thus enabling scientific measurements of ring particles from only a few kilometers.

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