Projects and grants

Conventional polymers and their more sustainable alternatives for air and water purification

SP2026/080

The project focuses on gaining a deeper understanding of the most common polymers, both conventional and greener ones, namely polyvinylidene fluoride (PVDF) and cellulose acetate, in air and water decontamination applications. PVDF is one of the most widely used polymers in membrane separation, but the disposal of used PVDF membranes is still the subject of research. PVDF polymer is inherently resistant due to the presence of a very strong covalent C-F bond, which gives this polymer great mechanical stability but also low degradability. For the above reasons, PVDF was selected as the model material for the first topic of this project proposal, which will focus on the degradation of PVDF in the form of a nanofiber fabric that could be used for the production of respirators. Given the growing number of detected released fragments of synthetic polymers (i.e., micro- and nanoplastics) in the environment, it is necessary to investigate the rate of its degradation. Therefore, it was selected as the material for one of the two topics of the project proposal, which will focus in particular on its degradation after the use of FFP2 respirators, in which PVDF serves in the form of a nanofiber layer for capturing particles at the level of tens to hundreds of nm. In the second topic of the application sphere, the project will focus on a more sustainable alternative, namely cellulose acetate and its use in its porous and nanofiber form for water purification and separation of micropollutants using its physicochemical modification. In the second topic of the application sphere, the project will focus on a more sustainable alternative, namely cellulose acetate and its use in its porous and nanofiber form for water purification and separation of micropollutants using its physicochemical modification. The suitability of materials will be evaluated in terms of functionality and sustainability with regard to the entire life cycle of a potential product, i.e., in individual steps from preparation through application to final degradation. Both topics within the project have common indicators: the preparation and characterization of polymer membranes, but their application differs with regard to the physicochemical properties of the selected polymers. Methodology Topic 1: Air decontamination application – use of PVDF nanofibrous membranes in FFP2 respirators and their post-application behavior with respect to the release of submicro- and nanoplastics after physicochemical exposure Preparation of PVDF polymer membrane: electrospinning Characterization (SEM, FTIR, contact angle) Stability assessment – UV degradation, rate of polymer particle release and their detection using STEM, ATR-FTIR, DLS Nanotextiles will be prepared in the laboratory using the electrospinning method (Nanospider technology) from PVDF polymers and compared with commercially available products. The polymers will be dissolved in suitable solvents (dimethylacetamide, acetone), considering purity and evaporation rate. At the same time, optimal dissolution of PVDF in so-called green solvents will be tested as alternatives to the above-mentioned ones. The solutions will be processed via electrospinning, optimizing parameters such as voltage, emitter–collector distance, temperature, humidity, and feed rate. The aim is to obtain nanotextiles with an optimal fiber diameter and reproducible properties. The prepared samples will be wrapped in aluminum foil, stored in glass containers, and analyzed using SEM (fiber morphology and diameter distribution) and FTIR (verification of chemical composition and possible structural changes). A scenario for the release of micro- and nanoplastics (MPs/NPs), i.e., particles ranging in size from tens of nm to hundreds of μm, from the initial PVDF textile will be designed and simulated. This includes UV irradiation (λ = 365 nm), which represents a component of solar radiation reaching the Earth's surface. The simulation will be carried out in quartz cuvettes, where membrane fragments will be exposed to UV radiation over several days. Subsequently, the membrane will be transferred into an aqueous environment, where ultrasound will be used to disperse its fragments into the liquid. This step is necessary for better handling of the sample and to prevent airborne release. The irradiated membrane will be characterized using the same techniques as before irradiation. Released fragments (sub-MPs/NPs) will be analyzed using DLS and STEM. STEM analysis is suitable for objects in both micrometric and nanometric ranges; morphology and partial size parameters (length, width) of sub-MPs and NPs will be evaluated. FTIR analysis will also be performed to identify potential changes in functional groups, particularly in submicron particles, which determine their reactivity. The size distribution of fibers and released particles will be evaluated using software tools such as ImageJ, Origin, or MATLAB. A time-dependent release curve of sub-MPs/NPs will be established by sampling at defined time intervals (hours to days) to quantify the number of released particles/fragments. Quantification in the submicron and nanometer range is challenging; therefore, the project will focus on developing suitable methods providing quantitative evaluation. One approach is particle counting from SEM or HRTEM images using ImageJ. All obtained data will be subjected to statistical analysis. Topic 2: Water decontamination application – use of cellulose acetate-based membranes for micropollutant degradation and study of their stability Preparation of polymer membranes from cellulose derivatives, specifically cellulose acetate (CA), using casting and electrospinning Modification of prepared membranes with selected photocatalysts (e.g., g-C3N4, modified TiO2, selected MOFs) Characterization (SEM, ATR-FTIR, TGA, contact angle measurement, XRD) Testing (water flux over time, separation efficiency) – indirect indicator of degradation Testing of degradation and mechanical stability after use – by periodic sampling and analysis of water CA membranes will be prepared using both casting and electrospinning methods. The polymer will be dissolved in two solvents: one conventional and one “green” alternative, selected with respect to their suitability for the given methods (e.g., evaporation rate, water miscibility). The aim is to compare the casting and electrospinning methods and evaluate the efficiency of both membrane types in terms of separation performance. Based on this comparison, the more suitable method will be selected for further preparation of modified membranes. Specifically, composite materials incorporating photocatalysts active under visible light (e.g., g-C3N4, modified TiO2, selected MOFs) will be prepared. The objective is to assess whether the photocatalytic materials negatively affect the structure of the CA matrix and whether they contribute to its degradation during water treatment. Another investigated aspect will be the photocatalytic degradation of selected micropollutants and its efficiency. All samples—both initial ones for method comparison and subsequent composites—will be characterized using the methods mentioned above and tested for separation efficiency and water flux. For photocatalytically active composites, photocatalytic performance will also be evaluated.

2026

2026

Ministry of Education, Youth and Sports

SGS

Specifický výzkum VŠB-TUO

Olšovská Eva Ing., Ph.D.