Ing. Dominik Pilnaj

Pyrolysis is a promising way of waste transformation into new valuable products. Pyrolytic oil is a mixture of hundreds of compounds and it requires detailed and accurate characterization for future applications. One of the most widely used techniques is mass spectrometry in combination with electron ionization. Tuneable ionization provides benefits including additional structural information and validation of molecular ion due to limited fragmentation at lower energies compared to conventional 70 eV, which provides spectral matches towards libraries. This approach was applied to the compounds identification and group characterization of virgin plastics polyvinyl chloride (PVC), polypropylene (PP), polystyrene (PS), high-density polyethylene (HDPE), low-density polyethylene (LDPE) and their mixture. The use of lower ionization energy was beneficial for distinction of alkanes, iso-alkanes and aromatics. On the contrary to 70 eV, significantly higher fragmentation in branching of iso-alkanes at 12 eV was observed with higher yield of molecular ion also for n-alkane. More than 50 % of detected peaks were identified up to the retention time of icosane. The main analytes of produced pyrolysis oil were monoaromatic (from PVC and PS), alkene/cycloalkane (from PP and mixture). In the case of HDPE and LDPE the main compounds were 1-n-alkenes and n-alkanes. The applied methodology reveals compound group, carbon chain length and degree of unsaturation with higher confidence and success rate compared to traditional nominal mass 70 eV datasets.

3D printing is an extensively used manufacturing technique that can pose specific health concerns due to the emission of volatile organic compounds (VOC). Herein, a detailed characterization of 3D printing-related VOC using solid-phase microextraction-gas chromatography/mass spectrometry (SPME-GC/MS) is described for the first time. The VOC were extracted in dynamic mode during the printing from the acrylonitrile-styrene-acrylate filament in an environmental chamber. The effect of extraction time on the extraction efficiency of 16 main VOC was studied for four different commercial SPME arrows. The volatile and semivolatile compounds were the most effectively extracted by carbon wide range-containing and polydimethyl siloxane arrows, respectively. The differences in extraction efficiency between arrows were further correlated to the molecular volume, octanol-water partition coefficient, and vapour pressure of observed VOC. The repeatability of SPME arrows towards the main VOC was assessed from static mode measurements of filament in headspace vials. In addition, we performed a group analysis of 57 VOC clas-sified into 15 categories according to their chemical structure. Divinylbenzene-polydimethyl siloxane ar-row turned out to be a good compromise between the total extracted amount and its distribution among tested VOC. Thus, this arrow was used to demonstrate the usefulness of SPME for the qualification of VOC emitted during printing in a real-life environment. A presented methodology can serve as a fast and reliable method for the qualification and semi-quantification of 3D printing-related VOC.

Environmental concerns push for a reduction in greenhouse gas emissions and technologies with a low carbon footprint. In the transportation sector, this drives the transition toward electric vehicles (EVs), which are nowadays mainly based on lithium-ion batteries (LIBs). As the number of produced EVs is rapidly growing, a large amount of waste batteries is expected in the future. Recycling seems to be one of the most promising end-of-life (EOL) methods; it reduces raw material consumption in battery production and the environmental burden. Thus, this work introduces a comprehensive pre-recycling material characterization of waste nickel-manganese-cobalt (NMC) LIB cells from a fully electric battery electric vehicle (BEV), which represents a basis for cost-effective and environmentally friendly recycling focusing on the efficiency of the implemented technique. The composition of the NCM 622 battery cell was determined; it included a LiNi0.6Co0.2Mn0.2O2 spinel on a 15 μm Al-based current collector (cathode), a graphite layer on 60 μm copper foil (anode), 25 μm PE/PVDF polymer separator, and a LiPF6 salt electrolyte with a 1:3 ratio in primary solvents DMC and DEC. The performed research was based on a series of X-ray, infrared (IR) measurements, gas chromatography–mass spectrometry (GC-MS), and inductively coupled plasma–optical emission spectrometry (ICP-OES) characterization of an aqueous solution with dissolved electrolytes. These results will be used in subsequent works devoted to optimizing the most suitable recycling technique considering the environmental and economic perspectives.

The popularity of lithium-ion batteries (LIBs) as crucial power sources has increased in recent years. LIBs represent a perspective technology for recycling because they comprise a high portion of valuable metals, such as nickel, manganese, cobalt, or lithium, and other metals, including aluminium, copper, and iron. Battery discharging represents an essential step in end-of-life (EOL) pretreatment, as it reduces the risk of fire or explosion in further processing. As a simple, quick, and inexpensive technique, an electrochemical discharging process via salt-based solutions is preferred for cylindrical cells. Nevertheless, it is necessary to consider the composition of obtained waste products and the possible environmental risks leading to their safe and non-hazardous EOL processing. This work evaluated discharging efficiency and environmental perspective for cylindrical LIB cells, which were treated using NaCl solution. All battery cells were discharged to the safe voltage limit (0.75 V) within 24 hours. Major organic components, including volatile solvents with high toxic hazards, such as carbonic acid esters, methyl salicylate, and propanoic acid esters, were identified in the waste solutions using gas chromatography with mass spectrometry (GC-MS). Moreover, the metal proportion in the solution was determined using inductively coupled plasma - optical emission spectrometry (ICP-OES) analysis; it is recommended to recover metals from the wastewater before EOL or cleaning treatment.

Poly(vinyl chloride) is widely used in the field of electrical engineering as an insulating material. Its properties are significantly dependent on the content of the plasticisers. In this work we identify plasticisers in commercially available insulated electrical wire. We quantify and qualify released hydrogen chloride and qualify volatile organic compounds at enhanced temperatures by thermogravimetric analysis, potentiometric titration, and gas chromatography-mass spectrometry system. Changes in glass transition temperatures and mechanical properties caused by enhanced temperatures are measured by dynamic mechanical analysis. The data show a significant release of hydrogen chloride above 180 °C, which has a significant effect on the mechanical properties.

The ever-increasing requirements for global carbon dioxide CO2 emission reduction decrease the production of new internal combustion engine vehicles (ICEVs). On the contrary, the demand for electric vehicles (EVs) increases along with the number of spent lithium-ion batteries (LIBs). Recycling LIBs seems to be one of the most promising options for end-of-life (EOL) treatment solutions; however, many process effects of currently used battery compounds are still being addressed, e.g., the safety and potential risks of wastewater, battery scrap, or leaks into the air. In this work, the LIB nickel-manganese-cobalt (NMC) cell electrolyte was characterized in wastewater using gas chromatography with mass spectrometry (GC-MS), inductively coupled plasma with optical emission spectrometer (ICP-OES), and the residues of toxic substances bound to nm-μm valuable metal particles in battery scrap were determined by x-ray fluorescence (XRF).