Abstract. Due to the increased concern of risks of oil spills in the Arctic marine environment, the search for alternative, a sustainable oil spill response technology has intensified. Especially, development of cost-effective, reusable and environmentally friendly sorbents from renewable resources have gained significant interest. The objective of this thesis was to study bio-based sorbents obtained from nanocellulose materials, i.e. aerogels, and address their oil absorption capacity and performance under Arctic marine conditions. Laboratory conditions were designed to simulate the conditions of Oulu and Tromsø ports. In general, nanocellulose based aerogels display high mechanical strength, high surface area, are cost-effective and safe to handle compared to many synthetic materials.
In this thesis, hydrophobized cellulose nanofibril aerogels produced from recycled fibre waste were used to absorb diesel and hydraulic oil. The nanofibrils were obtained using a simple and environmentally friendly nanofibrillation treatment after which aerogels were fabricated using freeze-drying process in the presence of two silylation agents. The Arctic weather conditions were simulated using a climate chamber. The weather conditions simulated were temperature, shaking and no-shaking frequency (to represent ocean waves), ice and no-ice condition and water salinity of 1% (Oulu port) and 3.5% (Tromsø port).
The nanofibrillation and hydrophobic silylation of waste cellulose fibres resulted in nanofibrillar aerogels, which had an ultralow density (0.01 g/cm3) and high porosity (99.15%) after freeze-drying and heating. The cellulose nanofibril aerogels showed higher oil (diesel and hydraulic) absorption performance in both 1% and 3.5% salinity than the commercial material. The diesel oil absorption by the nanofibril aerogel was higher in 1% salinity whiles the hydraulic oil absorption was better in 3.5% salinity. In particular, the nanofibril aerogels had diesel oil absorption capacity of 59.9 g/g (1% salinity) and hydraulic oil absorption capacity of 43.4 g/g (3.5% salinity), which is much higher to those of commercial absorbent materials, i.e. polypropylene, with diesel oil absorption capacity of 15.6 g/g in 1% salinity and hydraulic oil absorption capacity of 12.4 g/g in 3.5% salinity.
The shaking and icy conditions affected oil absorption with the nanofibril aerogels more than the commercial material. Overall, oil absorption was higher under shaking conditions compared to the no-shaking. The presence of ice decreased the absorption capacity of nanofibril aerogels and the commercial material. Generally, oil absorption capacity of the nanofibril aerogels was higher than that of the commercial material in all the conditions. The above advantages make nanofibril aerogels promising absorbents for removing oil spills from ports (Oulu and Tromsø).
| Identifer | oai:union.ndltd.org:oulo.fi/oai:oulu.fi:nbnfioulu-201906042314 |
| Date | 03 June 2019 |
| Creators | Okyere Abayie, S. (Samuel) |
| Publisher | University of Oulu |
| Source Sets | University of Oulu |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/masterThesis, info:eu-repo/semantics/publishedVersion |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess, © Samuel Okyere Abayie, 2019 |
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