In my master's thesis, I investigated the preparation, functionalization, and characterization of porous polyHIPE polymer materials and their application in the photocatalytic degradation of bisphenol A (BPA) in an aqueous solution. The polyHIPE materials were prepared using glycidyl methacrylate (GMA) and ethylene glycol dimethacrylate (EGDMA) as monomers through the polymerization of a high internal phase emulsion. I modified the monolithic supports using two different methods: by adding titanium dioxide (TiO₂) to the aqueous phase of the emulsion during synthesis and by subsequently treating the polyHIPE materials with titanium(IV) butoxide (TiBu). I then investigated the influence of the modification conditions on the properties of the resulting materials.
The morphology and elemental composition of the samples were analyzed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). I evaluated the flow properties of the polymers using chromatographic measurements, while the inorganic content was determined by thermogravimetric analysis. The results showed that the concentration of TiBu significantly affects the formation and quantity of titanium-containing structures, which are preferentially deposited on the outer surface of the polyHIPE materials. At a higher flow rate of the titanium precursor, particles were also observed within the internal porous structure of the polymer. For samples with TiO₂ added directly during synthesis, I found that the characteristic porous structure was preserved. At a lower TiO₂ concentration, the particles were relatively uniformly distributed, whereas at a tenfold higher concentration, larger agglomerates formed on the pore walls. The presence of titanium was also confirmed by EDS analysis. Thermogravimetric analysis further showed an increase in the proportion of inorganic residue with increasing concentrations of the precursor or the amount of added titanium dioxide.
When investigating the interactions between BPA and the polyHIPE materials, I found that the pH of the solution significantly affects BPA retention on the polymer column. At the unadjusted pH of the solution, all the injected BPA was retained on the polymer, whereas at pH 12, almost no BPA was retained. The photocatalytic degradation of BPA was monitored using UV–Vis spectrophotometry, which showed that the flow-through system was ineffective due to insufficient residence time. Therefore, a batch system was used in subsequent experiments, in which the BPA concentration decreased by 86 % after 300 minutes of UV irradiation. The time-dependent change in BPA concentration was described using a pseudo-first-order kinetic model, with an apparent rate constant of 0.0070 min⁻¹.
|
