Browsing by Author "Petrik, L"
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Item Modification of polyethylene terephthalate track etched membranes by planar magnetron sputtered Ti/TiO2 thin films(Elsevier, 2021) Petrik, L; Rossouw, A; Kristavchuk, OThis study investigates the surface modification of polyethylene terephthalate track-etched membranes by planar magnetron sputtering of titanium and titanium dioxide thin films to improve its hydrophilicity and photocatalytic activity. After cold plasma treatment to enhanced adhesion, Ti thin films were deposited by planar magnetron sputtering and TiO2 thin films by reactive magnetron sputtering in an Ar-O2 gas atmosphere. The morphology of the deposited thin films was characterised using atomic force microscopy and scanning electron microscopy. The pores retained a mostly circular shape. However, the modified track membrane's surface pore diameter reduced from 0.2 µm to 0.15 µm for Ti coated samples and 0.08 µm for Ti-TiO2 coated samples. Structural studies using X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy and Raman spectroscopy of Ti and TiO2 thin films revealed the intricate composition of the sputtered thin films which was a result of the complexity of sputtering on top of the porous polymer support. Additional investigations in surface wettability and bandgap showed a significant change in the track membrane surface's hydrophilicity and photocatalytic properties after depositing TiO2-Ti, adding to the self-cleaning properties of the coated TM.Item PM2.5 chemical composition and geographical origin of air masses in Cape Town, South Africa(Springer Science and Business Media Deutschland GmbH, 2021) Williams, J; Petrik, L; Wichmann, JPM2.5 in the indoor and outdoor environment has been linked in epidemiology studies to the symptoms, hospital admissions and development of numerous health outcomes including death. The study was conducted during April 2017 and April 2018. PM2.5 samples were collected over 24 h and every third day. The mean PM2.5 level was 13.4 μg m−3 (range: 1.17–39.1 μg m−3). PM2.5 levels exceeded the daily World Health Organization air quality guideline (25 μg m−3) on 14 occasions. The mean soot level was 1.38 m−1 × 10−5 (range: 0 to 5.38 m−1 × 10−5). Cl−, NO3−, SO42−, Al, Ca, Fe, Mg, Na and Zn were detected in the PM2.5 samples.Item Trace elements risk assessment for consumption of wild mussels along South Africa coastline(Elsevier, 2021) Petrik, L; Nekhoroshkov, P.S; Bezuidenhout, JThe study aimed to contribute to the scarce data on concentrations in the soft tissue of wild mussels growing in coastal cities of South Africa. The intake of 26 micro and macroelements was estimated. The mass fractions of sample sets from 8 sites along the South African coast from the West (Port Nolloth) to the East (Durban) were studied by neutron activation analysis at the Joint Institute for Nuclear Research (Russia). The following elements were identified as potentially hazardous due to high consumption risks: Al, Cr, Co, Zn, As, and I at stations in the Cape Town area (Waterfront, Hout Bay) and Durban. The mean concentrations of these elements among all individuals were 208, 0.8, 0.46, 60, 2.6, and 11 ppm of wet weight, respectively. In the studied mussels, the concentrations of Cr, Zn, As, and Se (ranging between 0.2−2.8, 14–290, 1.6−4.6, and 0.31−2.4 ppm of wet weight, respectively) exceeded maximum permissible levels for fish products. The weekly consumption of more than 250 g of fresh mussels per person could increase the risk for human health by potential intake of such elements as Al, As, and I