Oil spills and storm water runoffs can have serious impact on the environment with potentially major economic impacts. Given the limitation of current oil clean-up technique, the application of nanotechnology for oil remediation has been widely studied showing a promising avenue of research. This dissertation reports a cheap, facile and cost-effective nanotechnology-based oil clean-up technique that has been optimized for effectiveness and feasibility and reduced adverse environmental impacts. The synthesized polyvinylpyrrolidone (PVP)-coated magnetic nanoparticles (NPs) have been characterized using different techniques and the oil removal efficiency investigated under a wide range of environmentally relevant conditions. Based on the characterization data, NPs have a median particle size of 11.2 nm (interquartile range: 6.3--18.3 nm), a dominant phase of magnetite (Fe3O4) and 8.5% of the mass of NPs belong to their PVP coating. Oil removal experiment showed 100% oil removal from ultra-pure water using the optimum condition (NP concentration: 17.6 ppm, magnetic separation: 40 min). Gas chromatography--mass spectrometry results showed 100% removal of lower chain alkanes (C9-C21) and greater than 67% of C22-C25 removal. Using the same NP concentration, essentially 100% oil removal from synthetic freshwaters and sea water in the absence of natural organic macromolecules (NOM) was observed. Also, nearly 100% of C9-C20 alkanes were removed. The presence of NOM led to a statistically significant decrease in oil removal with NOM acting as a competitive phase for either PVP or oil and reducing NP-oil interactions driven by the hydrophobic effect of PVP coating (p-value< 0.05). Ionic strength facilitated oil sorption presumably by enhancing the magnetic separation of the oil-NP complex or altering PVP hydrophobicity (p-value < 0.05). Alteration of the separation conditions allowed optimal oil removal, with essentially 100% oil removal under most but not all conditions. Using the same type of NPs, the application of high gradient magnetic separation (HGMS) for the rapid removal of oil from oil-water mixtures in a continuous flow system was studied. Using a magnetic field of 0.18 T and 0.56 T, the oil removal percentage was 81.4% +/- 2.9 and 87.3% +/- 4.0, while the NP removal efficiency was 48.8% +/- 3.8 and 84.4% +/- 5.2, respectively. For a low magnetic field (0.18 T) and 1 h mixing, increasing the SS wool content from 0 to 100 mg, the oil and NP removal efficiencies increased from 81.4% +/- 2.0 to 86.7% +/- 0.9 and from 48.8% +/- 2.7 to 68.1% +/- 0.4, respectively. We also tested the HGMS system for a longer time by running the system for 7 h (3.5 h in two consecutive days) and treating nearly 17 L oil-water mixture. Using a magnetic field of 0.56 T and 1 h mixing time, oil and NP removal in presence and absence of SS wool was greater than 80%. This study proposes a promising nanotechnology-based oil remediation technique with a low adverse environmental impact and a significant potential for a large scale oil clean-up.