Background: Workers in a platinum group metals (PGMs) refinery are potentially exposed to various precious metals (iridium, osmium, palladium, platinum, rhodium and ruthenium) and their metal-salt compounds which may cause rhinitis, asthma, contact urticaria and conjunctivitis. Some cases revealed that sensitisation occurred in employees where it was not possible to detect any airborne soluble platinum or where the respiratory soluble platinum exposure was below the occupational exposure limit. It is unclear whether respiratory exposure or a combination of respiratory and dermal exposure may be involved in sensitisation and the possible elicitation of skin symptoms. Objectives: To determine if dermal exposure to PGMs took place during the refining process and in the administration area by using a removal method and to compare dermal exposure on the different anatomical areas and in two different working areas, Areas A and B for each of the PGMs. Methods: Dermal exposure samples were collected with a removal method using GhostwipesTM. The samples were collected from the palm of the hands, the wrists and the necks of the workers, before the shift started, before tea time, before lunch time and after the shift ended. The skin wipes were analysed for the PGMs (iridium, osmium, palladium, platinum, ruthenium and rhodium) according to Methods for the Determination of Hazardous Substances (MDHS) method 46/2, using Inductively Coupled Plasma-Mass Spectrometry. Results: No published data is available on occupational dermal exposure to PGMs in a precious metals refinery. This study proved that dermal exposure to PGMs in the refinery took place and was quantified. The PGM dermal exposure results in general, were very low (measured in nano grams), with platinum having the overall highest exposure. Exposure also occurred the most frequently during the last two intervals of the day, before lunch time and at the end of the shift. Exposure on all three the anatomical areas that were tested in the study, varied much with the palm of the hands having the highest exposure levels. There were also variations in exposure between areas A and B due to the fact that the processes in these two areas differ. Conclusions: It was confirmed that dermal exposure to PGMs took place at the precious metals refinery. The highest exposure took place before lunch time and towards the end of the shift. The metal to which the workers were exposed the most was platinum and the production area where the workers had the highest exposure to most of the metals was Area B. / MSc (Occupational Hygiene), North-West University, Potchefstroom Campus, 2015

Background: Workers in a platinum group metals (PGMs) refinery are potentially exposed to various precious metals (iridium, osmium, palladium, platinum, rhodium and ruthenium) and their metal-salt compounds which may cause rhinitis, asthma, contact urticaria and conjunctivitis. Some cases revealed that sensitisation occurred in employees where it was not possible to detect any airborne soluble platinum or where the respiratory soluble platinum exposure was below the occupational exposure limit. It is unclear whether respiratory exposure or a combination of respiratory and dermal exposure may be involved in sensitisation and the possible elicitation of skin symptoms. Objectives: To determine if dermal exposure to PGMs took place during the refining process and in the administration area by using a removal method and to compare dermal exposure on the different anatomical areas and in two different working areas, Areas A and B for each of the PGMs. Methods: Dermal exposure samples were collected with a removal method using GhostwipesTM. The samples were collected from the palm of the hands, the wrists and the necks of the workers, before the shift started, before tea time, before lunch time and after the shift ended. The skin wipes were analysed for the PGMs (iridium, osmium, palladium, platinum, ruthenium and rhodium) according to Methods for the Determination of Hazardous Substances (MDHS) method 46/2, using Inductively Coupled Plasma-Mass Spectrometry. Results: No published data is available on occupational dermal exposure to PGMs in a precious metals refinery. This study proved that dermal exposure to PGMs in the refinery took place and was quantified. The PGM dermal exposure results in general, were very low (measured in nano grams), with platinum having the overall highest exposure. Exposure also occurred the most frequently during the last two intervals of the day, before lunch time and at the end of the shift. Exposure on all three the anatomical areas that were tested in the study, varied much with the palm of the hands having the highest exposure levels. There were also variations in exposure between areas A and B due to the fact that the processes in these two areas differ. Conclusions: It was confirmed that dermal exposure to PGMs took place at the precious metals refinery. The highest exposure took place before lunch time and towards the end of the shift. The metal to which the workers were exposed the most was platinum and the production area where the workers had the highest exposure to most of the metals was Area B. / MSc (Occupational Hygiene), North-West University, Potchefstroom Campus, 2015

Abstract The large amounts of industrial wastewaters, contaminated by hazardous and toxic compounds together with ever tightening legislation, have challenged traditional wastewater treatment methods. Therefore, the development of discharge limits under, cost-effective and ecological wastewater treatment has become an essential concern. Catalytic water phase technologies are interesting alternatives for traditional wastewater treatment. Among them catalytic wet air oxidation (CWAO) has been used successfully in the management of various industrial effluents. However, the development of an active and stable catalyst for the severe reaction conditions of CWAO has proved truly challenging. The aim of this thesis was to study the activity and stability of laboratory prepared cerium supported metal catalysts in the catalytic wet air and wet peroxide oxidation of aqueous organic pollutants. Ru supported on Ce-Zr mixed oxides and commercial activated carbon as reference were used in CWAO and catalytic wet peroxide oxidation (CWPO) of surface plating industry wastewater. Ag/Ce-Zr and Pt/Ce-Ti catalysts were catalyzed CWAO of aqueous solution of bisphenol A (BPA). Both CWAO and CWPO improved the abatement of organic compounds from surface plating industry wastewater when comparing the non-catalytic experiments. Moreover, catalytic oxidation enhanced the biodegradability of organic matter in the wastewaters. According to the results, Pt/Ce-Ti catalysts performed with higher activity in CWAO of BPA than Ag/Ce-Zr catalysts and almost 100% removal of BPA was achieved. The leaching of active metal during oxidation experiments affected the activity of Ag/Ce-Zr catalysts. Moreover, CWAO of BPA was not a surface area specific reaction but the activity of catalysts was related to the chemisorbed oxygen content on the catalysts’ surface. The results of this thesis showed that cerium supported metal catalysts are active and stable catalysts in CWAO of BPA and also in the treatment of industrial wastewater. Therefore, these catalysts could be applied next to pilot scale applications. / Tiivistelmä Teollisuuden jätevedet sisältävät usein haitallisia ja myrkyllisiä yhdisteitä, joiden käsittely perinteisillä jäteveden käsittelymenetelmillä on hyvin haastavaa. Lisäksi alati kiristyvä ympäristölainsäädäntö asettaa omat vaatimuksensa jäteveden käsittelylle. Katalyyttiset vedenkäsittelymenetelmät ovat viime vuosina herättäneet paljon kiinnostusta. Yksi lupaavimmista tekniikoista on katalyyttinen märkähapetus, jota on käytetty sekä lukuisten malliaineiden että teollisten jätevesien käsittelyssä. Märkähapetuksen vaativissa reaktio-olosuhteissa aktiivisena säilyvän katalyyttimateriaalin kehittäminen on kuitenkin osoittautunut varsin haasteelliseksi. Väitöskirjatutkimuksen tavoitteena oli kehittää aktiivisia ja kestäviä ceriumpohjaisia katalyyttimateriaaleja märkähapetusreaktioon. Tutkimuksessa valmistettiin Ru-, Pt- ja Ag-katalyyttejä, jotka impregnoitiin Ce-Zr- ja Ce-Ti-sekaoksideille. Ru/Ce-Zr-katalyyttejä sekä kaupallista aktiivihiiltä vertailumateriaalina käytettiin pintakäsittelyteollisuuden jäteveden märkähapetuksessa ja märkäperoksidihapetuksessa. Bisfenoli A:n (BPA) vesiliuoksen märkähapetusta katalysoitiin sekä Ag/Ce-Zr- että Pt/Ce-Ti-katalyyteillä. Katalyyttisellä märkähapetuksella ja märkäperoksidihapetuksella pintakäsittelyteollisuuden jäteveden orgaanisten yhdisteiden konsentraatio väheni enemmän verrattuna ilman katalyyttiä suoritettuihin hapetuksiin. Lisäksi käsitellyn vesinäytteen biohajoavuusaste nousi eli jäteveden sisältämät orgaaniset yhdisteet olivat hapettuneet helpommin biohajoavaan muotoon. Pt/Ce-Ti-katalyytit olivat Ag/Ce-Zr-katalyyttejä aktiivisempia BPA:n märkähapetusreaktiossa. Pt-katalyyttisessä reaktiossa saavutettiin lähes 100 % reduktio BPA:n pitoisuudessa. Ag-katalyyttien aktiivisuuteen vaikutti hopean osittainen liukeneminen hapetettavaan liuokseen märkähapetusreaktion aikana. Lisäksi havaittiin, että BPA:n märkähapetusreaktiossa katalyytin aktiivisuus oli riippuvainen katalyyttipintaan kemiallisesti sitoutuneen hapen määrästä eikä niinkään katalyytin pinta-alasta. Väitöskirjatutkimuksessa saatujen tulosten perusteella valmistetut ceriumpohjaiset metallikatalyytit olivat aktiivisia ja kestäviä. Katalysoiduissa hapetusreaktiossa sekä BPA:n että pintakäsittelyteollisuuden jäteveden orgaaninen kuormitus pieneni. Siksi valmistettuja katalyyttimateriaaleja voitaisiin tutkia seuraavaksi pilotti-mittakaavan sovellutuksissa.