All predicted and hypothesized trends were proved. The relationship from Part A, where when temperature decreases, the mass of oil collected increases aligns with Curie’s Law. From Part C, it can be assumed that the higher the mass of oil collected, the stronger the magnetic field. Therefore, Curie’s Law, where magnetisation is inversely proportional to temperature was validated through this experiment. Looking at Graph A.3, it was surprising that the decrease in oil collected was so steep because the temperature only went up by increments of 5oC. The gradient of the graph is 0.4282 and range of values is 11.31g (see Graph C.7). Although the range is quite large, the magnetite still proved to be effective at the highest temperature.
In Part B, a linear relationship was revealed between salinity and mass of oil collected. The relationship between density and amount of oil retrieved from Part A was collated with the results from Part B to form Graph B.4. This graph displays a linear relationship between density of the water and mass of oil collected. In 2010, Samantha Ramirez examined how magnets act in liquids of different densities by measuring how fast it took for paperclips to be attracted to a magnet. She found that in cornstarch, the densest liquid at 1.4kg/m3, the paperclips moved the slowest due to its high viscosity. However, this was not seen when conducting the trials for Part B, and any slow movement of particles had no noticeable effect on the data and overall trend. This may be due to that the densities tested only ranged from 995.7 to 1028.61kg/m3.
Unexpectedly, looking at the whole range of data in Graph C.7, the electromagnet with the most number of turns did not collect the most magnetite, instead it was the water with the highest salinity. However, when comparing the gradient of Graph B.3 (0.4472) and C.6 (1.464), the gradient of C.6 is three times that of B.3. Therefore, as number of turns increases, the mass of oil collected would increase far more rapidly than if mass of salt per litre were to increase because the graph is steeper. If a larger number of turns were used, the electromagnet could have been stronger and possibly retrieved the largest amount of oil. However, the iron nail used could only fit 30 turns, if this experiment is done again, a longer nail should be used to explore a larger sample space.
Looking at Graph C.9, it can be seen that using magnetite is about 7-27% effective with the majority of the results lying between 11-19%. The reason this percentage is small is most likely due to not enough magnetite being used compared to the amount of oil used. 10g of magnetite was used for 100g of oil due to limitations of resources. From Graph C.10, it was determined that as mass of magnetite collected increases, mass of oil collected increases. The gradient of the graph is 4.3039, one gram of magnetite collected can approximately collect four grams of oil. Therefore, with a strong enough magnet, approximately 25g of magnetite could retrieve the 100g of oil.
Validity is defined as if the experiment is fair or not. The controlled variables of experiments A, B and C were kept constant through all testing. For experiments A and B the same magnet was used to ensure there were no variations in the strength of the magnet. The experiment addressed the research question and the aim directly. Valid materials were used such as magnetite collected from the beach. Validity could have been improved if a heavy oil such as diesel was used to better model a real oil spill. A validity issue is that the boom weighed after immersion may have collected some water, hence, decreasing the amount of oil that was actually collected. This possible room for error was minimised by allowing the boom to drip for a few seconds to force the water to drip off, but leaving the oil which remained in a colloidal suspension with the magnetite. However, there is still potential for water to have been a part of the measured mass of oil, hence affecting validity.
Since there is no true value to compare the results to, accuracy cannot be fully assessed. However, the trends found for temperature vs magnetisation and strength of electromagnet vs number of coils were accurate. For all measurements of each part, three trials were conducted. Originally, five trials were to be conducted but after realising the scale of the experiment due to the amount of water and oil required and also the several days needed for the magnetite to dry, only three trials were conducted in the end to minimise time taken and wastage of resources. Graph C.8 shows that standard deviations range from 0.04-1.07, with the majority lying between 0.12 and 0.37 which is determined as consistent because it is below 1 (Kaufmann, 2014). Therefore, the experiment had very consistent results and the multiple trials reduced random error, hence, the experiment is reliable.
In 2016, Rebekah Kang carried out a similar experiment where she looked at how magnetite and magnets can be used to improve the ability of organic sorbents to collect oil. Figure 21 is a graph from her report and her results indicate, a noticeable increase in the mass of oil retrieved when magnetite is used. Mass of oil retrieved increased by around 4% – 220%. These results indicate that magnetite could also be used to further the effectiveness of processes already in place such as booms.
In a world where five trillion litres of oil are consumed each year in the world (Rapier, 2018), oil spills are almost inevitable. This experiment explores the potential of magnetite as a viable method of cleaning up oil spills, which is efficient, effective and most importantly, harmless to the environment. If the magnetite is not fully removed, iron actually stimulates phytoplankton growth, which consumes carbon dioxide through photosynthesis, hence reducing the greenhouse effect, therefore, magnetite has no harm to the environment (Horton, n.d.). Further research could be done into exploring how magnetite could be used clean sunken oil, which was a major problem in the 2010 BP oil spill. Further testing should also be done on the environmental effects of magnetite. Oil spills are sadly unavoidable due to high demand of oil; therefore, it is vital that an effective response strategy is in place.