TY - THES

T1 - Degradation of model reactants as a chemical probe for cavitation induced hot spots in water treatment devices

AU - Vallant, Daniel

N1 - embargoed until 09-03-2021

PY - 2016

Y1 - 2016

N2 - Cavitation is the formation, growth and implosion of vapor bubbles in a liquid medium (Capocelli et al. 2014, S. 2566) causing localized high temperature (1000 - 10000 K) and pressure (100 - 500 bar) for a few nanoseconds (Kenneth S. Suslick 1990). A number of studies show that these so called “hot spots” lead to the generation of free radicals like( OH) ̇ and H ̇. They are produced through the homolytic dissociation of water and used to oxidize complex contaminants in waste water streams (Advanced Oxidation Process (AOP)). This is the point where in this thesis the term cavitation is strictly differentiated from the damaging event of cavitation. Two different kinds of cavitation are considered: The first, hydrodynamic cavitation (HC) is performed with the patented cavitation unit from Arisdyne systems Inc., which is implemented into a closed loop. The second is ultrasonic cavitation (UC) which is realized through an ultrasonic horn. To investigate the degradation and the existence of cavitation induced hot spots, three different model reactants are used for the experiments: The liberation of iodine (Weissler reaction), the oxidation of sulfite to sulfate and the metabolization of PNP (p-nitrophenol). Samples are prepared for photometric measurement (UV/VIS spectrometer) and the performance of the HC loop is compared with the UC setup. The HC is studied over the pressure range 1000 - 15000 psi and the results of all three model reactants demonstrate that an applied pressure of 1000 psi shows the biggest degradation effect. All HC results are compared with the UC under the same operating parameters like temperature and pH. On the one hand the findings of this study indicate the existence of cavitation induced hot spots through HC and on the other hand it provides a possibility to monitor them quantitatively. Future investigation will be about the scale-up of the used HC system and if it is suitable for different applications like the cracking of long-chained hydrocarbons in the oil industry or the removal of persistent contaminants in waste water streams.

AB - Cavitation is the formation, growth and implosion of vapor bubbles in a liquid medium (Capocelli et al. 2014, S. 2566) causing localized high temperature (1000 - 10000 K) and pressure (100 - 500 bar) for a few nanoseconds (Kenneth S. Suslick 1990). A number of studies show that these so called “hot spots” lead to the generation of free radicals like( OH) ̇ and H ̇. They are produced through the homolytic dissociation of water and used to oxidize complex contaminants in waste water streams (Advanced Oxidation Process (AOP)). This is the point where in this thesis the term cavitation is strictly differentiated from the damaging event of cavitation. Two different kinds of cavitation are considered: The first, hydrodynamic cavitation (HC) is performed with the patented cavitation unit from Arisdyne systems Inc., which is implemented into a closed loop. The second is ultrasonic cavitation (UC) which is realized through an ultrasonic horn. To investigate the degradation and the existence of cavitation induced hot spots, three different model reactants are used for the experiments: The liberation of iodine (Weissler reaction), the oxidation of sulfite to sulfate and the metabolization of PNP (p-nitrophenol). Samples are prepared for photometric measurement (UV/VIS spectrometer) and the performance of the HC loop is compared with the UC setup. The HC is studied over the pressure range 1000 - 15000 psi and the results of all three model reactants demonstrate that an applied pressure of 1000 psi shows the biggest degradation effect. All HC results are compared with the UC under the same operating parameters like temperature and pH. On the one hand the findings of this study indicate the existence of cavitation induced hot spots through HC and on the other hand it provides a possibility to monitor them quantitatively. Future investigation will be about the scale-up of the used HC system and if it is suitable for different applications like the cracking of long-chained hydrocarbons in the oil industry or the removal of persistent contaminants in waste water streams.

KW - Cavitation

KW - Hydrodynamic cavitation

KW - Ultrasonic cavitation

KW - model reactants

KW - model reactions

KW - cavitation induced hot spots

KW - waste water treatment

KW - Advanced Oxidation Process

KW - AOP

KW - liberation of iodine

KW - sulfite oxidation

KW - degradation of PNP

KW - Kavitation

KW - Hydrodynamische Kavitation

KW - Akustische Kavitation

KW - Modellreaktanten

KW - Modellreaktionen

KW - Abwasserreinigung

KW - Hot Spots

KW - Freisetzung von Jod

KW - Oxidation von Sulfit

KW - Abbau von PNP

M3 - Master's Thesis

ER -