Examensarbeten på grundnivå

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    Investigating the corrosive effect of KCl on the low alloyed steel T22 at 400°C
    (2022) Warvne, Jonathan; Chalmers tekniska högskola / Institutionen för kemi och kemiteknik; Liske, Jesper; Lindmark, Hampus
    Substituting fossil-fuels with waste- and biomass during combustion for heat-and power production has proven to be a viable, more environmentally friendly energy source. It does however come with new problems, one being the release of a diverse flue gas containing different chlorine species such as KCl, HCl and PbCl2 which are known to greatly accelerate the corrosion of low-alloyed steels commonly used in the waterwall region of waste-fired boilers. To solve this problem a better understanding of the corrosive mechanisms at play during chlorine-assisted corrosion of low alloyed steels at high temperatures is required. This thesis aims to investigate the corro sive effect of KCl on the low-alloyed steel T22 at 400°C through the use of several analytical techniques such as SEM, EDX and XRD. The results reveal that KCl greatly increases the magnitude of corrosion under these conditions as can be seen by both mass-gain data, SEM images and by the extensive crack formation found on salt affected samples after 168h of exposure. XRD-data confirmed the forma tion of Hematite(Fe2O3) and Magnetite(Fe3O4) on nearly all samples. EDX results indicate that Cl can diffuse through the oxide scale and reach the metal interface where it is proposed to form volatile metal-chlorides according to the chlorine cycle mechanism.
  • Post
    lektrokemisk undersökning av katalysatorlagret i PEM-bränsleceller
    (2022) Hurtig, Adam; Eriksson, Joel; Chalmers tekniska högskola / Institutionen för kemi och kemiteknik; Karlsson, Maths
    The fuel cell industry is an industry with tremendous potential, but before it can reach new heights and mainstream use in society there are some obstacles to be overcome. One of these is the heavy price tag of the used Platinum catalyst and therefore the need to improve and optimize the use of said catalyst. A way of eva luating this optimisation is by analysing the electrochemically active surface area (ECSA) of a catalyst coating, using a rotating disc electrode (RDE). This was done for this project, where the effect of the dispersion on the catalyst ink and coating was analysed using an RDE and a reliable method for the analysis is proposed. In the beginning the results showed big fluctuations of ECSA and the method was therefore considered too unreliable. A new method with 60 cleaning scans, run 2 times was therefore proposed and tested. This new method was deemed to achieve reproducible results and was therefore used in subsequent analyses. These analyses showed that dispersion of the ink is required for reproducible results and they in dicated that the ECSA decreases with increasing amplitude during dispersion and increasing dispersion energy after a certain threshold. Although further investiga tion is required in order to confirm these indications. The maximum ECSA of 77,6 m2/gP t was found after dispersing an ink with 60% amplitude to a total energy of 6300 Ws.
  • Post
    Evaluating the properties of recycled polyethylene films from the construction industry
    (2022) Nord Nilsson, Hannes; Andersson, Julia; Chalmers tekniska högskola / Institutionen för kemi och kemiteknik; Petranikova, Martina
    The construction industry generates tonnes of plastic waste every year and only a small minority of this is recycled. This study looks into possible new film products in the construction industry, if the waste is collected, by evaluating the properties of the mechanically recycled film. The plastic in question is transparent polyethylene (PE) film from a construction specialist shop, sorted into four categories; shrink and stretch films, clean film, dirty film, and thick film. The evaluation of the properties was done through various tests, these were; Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), melt flow index (MFI), oxidative induction time (OIT), tensile strength test, density and thickness measurements, falling dart, and tear strength and the results were analyzed separately. The results show that it is possible to turn all categories into covering film, hoods, and garbage bags, although the clean film is the only one that does not require any extra measures. The others need to be washed or mixed with virgin material to stabilize some property in order to be made into new products. In addition, an environmental system analysis was performed which revealed that it is environmentally beneficial to recycle PE in terms of carbon dioxide (CO2) equivalents.
  • Post
    Synthesis of lactide using residual product from Kraft process
    (2022) Strömberg, Bryan; Josoph, Nuura; Chalmers tekniska högskola / Institutionen för kemi och kemiteknik; Westman, Gunnar
  • Post
    Recycling of steel swarf via hydrometallurgy. Purification of iron chloride solution via solvent extraction, cementation, and ion exchange – a comparative study
    (2021) Saami, Melis Yudzhel; Chalmers tekniska högskola / Institutionen för kemi och kemiteknik; Retegan Volmer, Teodora; Petranikova, Martina
    Several methods for purification and recovery of metals present in a swarf solution obtained from steel production and manufacturing waste are being tested in this study. The valuable elements originally present in the waste are Fe, Mn, Ni, and a small amount of Cr. The purification methods include solvent extraction with acidic and solvating extractants, cementation with an iron plate and ion exchange with the chelating resin Dowex M-4195. The extractants Cyanex 272 and D2EHPA extracted the highest amounts of Fe in comparison to the other acidic extractants. Both Cyanex 272 and D2EHPA reached 45% of Fe extraction at pH=3. Coextraction of Mn and Ni did occur in both cases indicating that solvent extraction is not the best approach for purification of the swarf. The solvating extractants TBP, Cyanex 923 and Aliquat 336 were tested at the same conditions, without adjusting the pH. Cyanex 923 extracted mostly Fe that reached 14% with less than 1% co-extraction of Mn and Ni. TBP and Aliquat 336 were inefficient in this case. A cementation technique with a piece of iron plate did not give any significant difference in metal concentration before and after the experiments. The best results are obtained from the ion exchange experiments with Dowex M-4195 at 25°C, 40°C and 60°C, shaking speed at 150 rpm for a total of 4h. Increasing amounts of Ni adsorption were observed at higher temperatures and longer shaking time. More than 95% of Ni got adsorbed by the resin at 60°C after 4h, the absorption reached 96% at room temperature after 48h. Co-extraction of the other metals decreased with increasing temperature concluding that ion exchange at temperatures above 40°C is the best method for purification of the swarf in comparison to solvent extraction and cementation.