The Effect of Temperature on the Zeta Potential of Magnetite Particles in Ammonia, Morpholine and Ethanolamine Solutions

Research output: ThesisMaster's thesis

Abstract

In nuclear power plants, flow accelerated corrosion releases magnetite particles from the surfaces of the feed water pipes. When these colloidal particles reach the steam generator, they can deposit to the surfaces of the steam generator and produce possibly dangerous and expensive material and thermal degradation phenomena. This deposition is presumed to be affected by the surface charge of the particles, which can be described with the zeta potential. In this thesis, the zeta potential of magnetite particles in ammonia, morpholine and ethanolamine solutions were measured at the temperatures from 23˚C to 248˚C. The zeta potential measurements were conducted with a streaming potential measuring equipment designed for these measurements. The change in the pressure difference over the column containing magnetite powder and the change in the potential difference between platinum electrodes situated at the both ends of the column were measured as a function of the velocity of the water flow. The resulting ΔE/ΔP was then multiplied with a calculation constant which consisted of the dimensions of the magnetite column, the resistance of the column and the viscosity and the actual permittivity of the solution. In order to conclude these measurements, the measuring equipment was first updated for higher measuring temperatures. The aim of this thesis was to determine how the zeta potential of magnetite particles changes as a function of temperature when the pH at room temperature is 9.2. It was found out that at room temperature magnetite has a negative zeta potential in ammonia, morpholine and ethanolamine solutions. Increasing temperature resulted in a decrease of the zeta potential magnitude. Near the operational temperature of the steam generator, zeta potential seemed to approach a small but still negative value in all cases. A low zeta potential value can be interpreted as an indication of rather weak repulsive forces between the colloidal magnetite particles and an increased possibility for coagulation and deposition.
Original languageEnglish
QualificationMaster Degree
Awarding Institution
  • Aalto University
Supervisors/Advisors
  • Forsén, O., Supervisor, External person
  • Saario, Timo, Advisor
Award date9 Dec 2013
Publisher
Publication statusPublished - 11 Feb 2014
MoE publication typeG2 Master's thesis, polytechnic Master's thesis

Keywords

  • zeta potential
  • magnetite
  • steam generator
  • PWR
  • pressurized water reactor
  • ethanolamine
  • ammonia

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