Skim Or Soak Lab Report

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Skim or Soak Lab Report Lara Glendening and Marilynn Hunt March 19, 2019

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Abstract In this experiment, we tested the best method of soaking up the oil. We tested two different methods: leaving the sorbent to soak up the oil and skimming it across the surface of the oil. We used cooking tins filled with 6 cups of salt water to 2 cups of oil. We used cotton fiber as our sorbent since we determined in our previous experiment that it was the most effective. In the first set of trials, we left a square of cotton fiber to soak for 2 minutes. In the second, we pulled it back and forth for 2 minutes. In the “soak” trials, the cotton absorbed an average of 28.3 mL of oil. In the “skim” trials, it absorbed an average of 33.3 mL of oil. Because of this, we concluded that the “skim” method was the most effective. This makes sense because the sorbent is able to reach more oil.

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Table of Contents Introduction…………………………………………………………………………………...….4 Method………………………………………………………………………………………....4-6 Results……………………………………………………………………………………...….6-8 Discussion…………………………………………………………………………………......8-9 Conclusion…………………………………………………………………………………..….10 References…………………………………………………………………………………......10 Appendix………………………………………………………………………………………..11

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Introduction There are many existing methods of oil spill cleanup, including sponges to soak up the oil and skimmers to skim oil off the surface. In this experiment, we wanted to find out if these two methods can be combined. In order to test this, we must first know how to measure volume. Since the measurements in beakers can be inaccurate, we used the volume equation to verify our measurements. 2​ V=​ πr​ h

Equation 1: Volume of a Cylinder

In this experiment, we will conduct multiple trials using a soaking method and a skimming method to answer the question, “can a sponge be used like a skimmer to increase the amount of oil it reaches?” We hypothesize that the answer to this question will be yes since the skimming method allows the sponge to cover more surface area.

Methods Squares of cotton fiber were first skimmed across the surface oil for 2 minutes, then soaked in the oil for 2 minutes. Each trial was repeated three times. The amount of oil squeezed out of each sponge was recorded after each trial.

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Apparatus: The experimental apparatus includes three large disposable cooking tins, which are each filled with 6 cups of salt water and 2 cups of oil. During the “skim” trial, tweezers are used to glide a 3.75” by 3.75” square of cotton fiber back and forth across the surface. During the “soak” trial, a cotton fiber square of the same dimensions soaks in the middle of the tub. A 500 mL graduated cylinder was used to measure and pour the oil, a 2 cup measuring cup was used for the water, and a 500 mL beaker was used to measure the amount of oil squeezed out of the cotton fiber sponge after each trial. There was also a timer to ensure each trial was the same length.

Figure 1: Digital Drawing of Apparatus

Figure 2: Sketch of the Apparatus

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A detailed list of the equipment used in this experiment and their uncertainties is shown in Table 1.

Equipment

Uncertainty

500 mL graduated cylinder

+/- 5 mL

500 mL beaker

+/- 5 mL

2 cup measuring cup

+/- 2 tbsp

Table 1: uncertainty of equipment

Procedure: 1. Fill a tub with 6 cups of water, add salt, and wait until it is at room temperature 2. Add 2 cups of oil and let it sit for 1 minute 3. Hold the sponge with tweezers and glide it across the top of the water from one end of the tub to the other for 2 minutes 4. Measure how much liquid it has absorbed, and how much of the liquid was oil and how much was water (do this in a beaker so that they separate) 5. Repeat step 1-2 but then drop the sponge into the tub and leave it there for 2 minutes 6. Measure how much liquid it has absorbed, and how much of the liquid was oil and how much was water (do this in a beaker so that they separate) 7. Repeat 3 times

Results The skimming method resulted in more oil being soaked up than the soaking method. The values of oil absorbed in each trial appear in table 2. The skimming method averaged 33.3 mL of oil-soaked up, while the soaking method averaged 28.3 mL.

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Trial

Oil soaked up

Uncertainty

Skim 1

30 mL

+/- 5 mL

Skim 2

35 mL

+/- 5 mL

Skim 3

35 mL

+/- 5 mL

Average for skim

33.3 mL

+/- 5 mL

Soak 1

35 mL

+/- 5 mL

Soak 2

25 mL

+/- 5 mL

Soak 3

25 mL

+/- 5 mL

Average for soak

28.3 mL

+/- 5 mL

Table 2: Results of Experiment

The results and uncertainties were then graphed to visualize the data. Error bars were created using the uncertainty of the measuring materials.

Figure 3: Experimental Results

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The data shows that the “skim” method absorbed more oil than the “soak” method, though there is error to take into account.

Discussion Our driving question in this experiment was whether or not a skimming motion increases the amount of oil soaked up by a cotton fiber sponge. Based on the data collected in out experiments, we can confirm that it does increase the amount of oil collected. The average amount of oil soaked up during the skim experiment, 33.3 mL, is 5 mL more than the amount of oil soaked up during the soak experiment (28.5 mL). Although our apparatus did have an uncertainty value of +/- 5, we believe that there was an outlier in the soak data caused by human error, and the soak average should have actually been lower. This will be explained further in our error analysis.

The results seemed to follow a general pattern, except for one outlier. The amount of oil collected in the first soak trial is 35 mL, which is 10 mL higher than either of the other values for the soak method. In fact, it was the highest value collected in the entire experiment, along with one other 35 mL value in the skim trial (which is much more consistent with the other results). Because this value is so anomalous, it can be ruled as an outlier. We believe that it ended up so high because there was extra oil in the graduated cylinder we used to measure the oil collected by the sponge. It was the first measurement we did after using the same graduated cylinder to pour oil into the tub, and we believe there was some oil left over at the bottom that inflated the number. It is

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impossible to tell how much oil it was, which is why we would like to run more repeats of the experiment to obtain more accurate data.

Another possible source of error is in our measuring. It is possible that the amounts of water, salt, and oil in each tub may have differed, so the experiment may not have been fully controlled. Also, the size of the cotton fiber squares may not have been exactly the same. If we repeat this experiment, we would like to obtain more accurate measuring tools.

Along with repeats of the same experiment, we would like to do further experiments branching off of this one. We would like to test more practical methods of skimming the sponge back and forth, since using tweezers is highly impractical in the real world. Some ideas are a drone to pull the sponge back and forth or a boat to drag it through the water. Another experiment we would like to perform is one that would determine the best shape for our sponge that would allow it to reach and soak up the most oil. Along with these experiments would come considerations about the size of the sponge, especially in relation to what will be dragging it.

Overall, we came to the conclusion that a skimming method is the best way to collect surface oil, confirming our hypothesis.

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Conclusion/Summary Our data showed that a skimming method is more effective than a soaking method for collecting surface oil. The skimming method collected an average of 33.3 mL of oil, while the soaking method collected an average of 28.3 mL. This is because it is able to reach more oil instead of only collecting oil from one place. Due to human error in measurements, we would like to do more trials of this experiment. We would also like to conduct experiments to determine the shape of our sponge and the mechanism that will drag it through the water. These experiments are possible now that we have determined the basic method of collecting oil for our sponge.

References “EPA's Response Techniques.” ​EPA,​ Environmental Protection Agency, 30 Jan. 2018, www.epa.gov/emergency-response/epas-response-techniques​. “Cleaning up the Oil Spill.” ​Science Learning Hub​, 11 Jan. 2012,​ ​www.sciencelearn​. org.nz/resources/1140-cleaning-up-the-oil-spill.

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Appendix