Synthesis and Filtration Dewatering of Model Colloids in the μm Range

Student thesis: Master thesis (including HD thesis)

  • Søren Lorenzen
4. term, Chemistry, Master (Scient) (Master Programme)
When a membrane filtration process is to be used, a preceding model of the interactions between the suspended solids and the membrane is often required. Most of the mathematical models used today, stem from experiments using inorganic particles and are often inadequate in describing complex systems, such as municipal and industrial waste water. Filter cakes composed of such organic solids are often both compressible and negatively charged. To improve these models, organic particles with controllable properties, are in need.
This work investigates the dispersion polymerization, of methyl methacrylate with polyvinyl-pyrrolidone as stabilizer, as well as styrene with poly(acrylic acid), as a possible method to produce particles with the wanted properties.
The first part of this work describes the dispersion polymerization employed and is a combination of literature studies and experimental work. The second part is dead end dewatering filtration of the produced particles and are composed of a description of the mathematical models used today, to predict the specific resistance to filtration, α, followed by the results from the filtration experiments.
It was found that the values of α, when filtering particles made from methyl methacrylate and polyvinylpyrrolidone, are quite close to the predicted value, whereas α is significantly higher for the particles produced from styrene and poly(acrylic acid), probably due to the interactions taking place between the charged surface of the particles and the surrounding water.
In addition to this, only one of the particles showed a slight pressure dependency of α and only at longer filtration times (larger volumes). This is possibly caused by the addition of surface active monomer during the synthesis, which might create a higher osmotic pressure around the particle.
When smaller and larger particles were mixed, the resistance was shown to mainly be governed by the smaller particles, probably due to blinding effects, where the smaller particles fill the voids between the larger.
Publication date31 May 2012
Number of pages59
ID: 63478607