Abstract:
This dataset contains results from low energy dispersion tests (LEDTs) on dispersants containing different solvents. The data were analyzed using the Hansen Solubility Parameter (HSP) plots. This dataset supports the publication: Fernandes, J. C., Agrawal, N. R., Aljirafi, F. O., Bothun, G. D., McCormick, A. V., John, V. T., & Raghavan, S. R. (2019). Does the Solvent in a Dispersant Impact the Efficiency of Crude-Oil Dispersion? Langmuir, 35(50), 16630–16639. doi:10.1021/acs.langmuir.9b02184
Suggested Citation:
Fernandes, Jay C.; Agrawal, Niti R.; Raghavan, Srinivasa R.. 2020. Dataset for: Does the Solvent in a Dispersant Impact the Efficiency of Crude-Oil Dispersion?. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/PTKX4HDT
Data Parameters and Units:
The data are organized under six sub-folders. The folders are labelled corresponding to the figures in the associated publication, Fernandes et al., 2019. The data included in each folders are described below:
The folder "Figure 3": This folder contains results from the low energy dispersion test (LEDT) on dispersing crude oil in seawater using dispersants made with 18 different solvents. All dispersants have the same surfactant blend containing 40 wt% solvent and 60 wt% surfactant with constant surfactant composition of Lecithin/Tween 80 (L/T) = 60:40 w/w. Normally, the overall weight of dispersant was 1 g (0.36 g L, 0.24 g T, and 0.4 g solvent). 30 min after the conclusion of the low-energy agitation photos were taken. Image 9 to Image 26 represents the dispersant containing solvents in the following order: 1-octanol, 1-undecanol, diethylene glycol ethyl ether, 3-octanol, 2-ethyl-1-hexanol, 1-butnaol, diethylene glycol butyl ether, ethylene glycol butyl ether, dipropylene glycol, 1-propanol, ethanol, acetic acid, 1,3-butanediol, isopropanol, methanol, diethyleneglycol, isobutanol and propylene glycol. In addition, the results are grouped into three categories: good, moderate, and poor dispersion. A brown water column is an indication of a high concentration of relatively stable oil droplets and is considered a “good” dispersion. On the other hand, a colorless water column where much of the oil droplets have coalesced and risen above the water is thought to be a poor dispersion. This is observed by the optical micrograph for the dispersant with Propylene Glycol as a solvent. This folder also contains micrographs for two different LEDTs. One micrograph corresponds to a LEDT in which 1-octanol is the solvent used in the dispersant (Image 8). The 1-octanol micrograph shows many small oil droplets present in the water column, indicating a good dispersion. The second micrograph corresponds to a LEDT in which Propylene glycol solvent is used in the dispersant (Image 7). The Propylene glycol micrograph shows very few oil droplets present in the water column, thus indicating a poor dispersion.
The folder "Figure 4": This folder describes results from the LEDT on dispersing crude oil in seawater using no surfactants. In two of the tests (shown in image 27 and 28), a solvent alone is used. The first solvent is 1-octanol (Image 27) (best solvent from the 18 solvents tested), and the second solvent is Propylene glycol (Image 28) (worst solvent from the 18 solvents tested). A third LEDT, in which neither surfactant no solvent is used (Image 29), was performed. There was negligible dispersion of the oil in all three samples.
The folder "Figure 5a": This folder contains the comparison of results from the LEDT and the Baffled Flask Test (BFT) on the same samples. Results are for spreading crude oil in seawater using the same surfactant blend (L/T = 60:40) solubilized in 1-octanol. The dispersant/oil ratio (DOR) is changed from 1:10 to 1:100. Values for BFT efficiency (%), values for sample transmittance (%), and standard error from the LEDT are all contained in the associated Excel file.
The folder "Figure 5b": There are a set of photos of the flasks from the LEDTs for the dispersant containing 1-octanol as a solvent. In addition, there are a set of photos of the flasks from the BFTs. Images 28 to 32 represent LEDT vial images for DORs 1:10, 1:25, 1:50, 1:75 and 1:100 respectively. Whereas, images 33 to 37 represent BFT images for DORs 1:10, 1:25, 1:50, 1:75 and 1:100 respectively.
Folder "Figure 6, 7, 8": The worksheet "Fig 6" contains the data used construct the figure 6 which is Hansen Solubility Parameter (HSP) values (the solubility of the L/T surfactant blend in numerous solvents). Each solvent has a pair of HSPs. The two HSPs of interest are the HSP for polar interactions δ~P~, and the HSP for H-bonding interactions δ~H~. Sheet “Fig-6” in the Excel file contains a list of solvents that solubilized the surfactants denoted as “Soluble Solvents”, whereas the solvents that did not solubilize the surfactants are denoted as “Insoluble Solvents”. The results from the 18 LEDTs are shown in the Excel file (sheet Fig-7) and are denoted numerically using two HSPs. The first HSP being that for the polar interactions, and the second being that for the H-bonding interactions. Solvents are categorized into insoluble, good dispersion, medium dispersion and poor dispersion. The effect of solvent on the efficiency of crude-oil dispersants is quantified using the Ra values, i.e. the distance from crude-oil on the HSP plot. The Excel sheets for Fig 8a and 8b include the HSP value for crude oil and the bar graph representing the Ra values for solvents giving good, moderate and poor dispersions. Please note dP = interactions between solvent molecules to polar interactions; dH = interactions between solvent molecules to hydrogen-bonding.
The folder "Table 1, S2": The Excel file "Table 1" includes the toxicities of candidate solvents for use in dispersants. It contains the reported values for each solvent (from their Materials Safety Data Sheets) of the median lethal dose (LD50) in cases of dermal and oral administration are shown. The categories for toxicity are: Categories 1 and 2 = fatal, Category 3 = toxic, Category 4 = harmful, Category 5 = may be harmful. Optimal Solvents for Use in Dispersants Based on L/T Surfactants. The optimal solvent should yield good dispersant efficiency, have a flash point that is sufficiently high (at least 60°C), and exhibit low toxicity. The top 3 solvents, identified by the aforementioned criteria are shown in the Excel file, along with their relevant data. The Excel file "Table S2" contains viscosity data for the 18 soluble solvents, at 25 °C (mPa.s).
Methods:
The description of the experiments are described below:
Low Energy Dispersion Test (LEDT): For LEDT, 100 mL of seawater was added to a 125 mL conical flask, followed by addition of 100 μL of Sweet Louisiana crude oil and 10 μL of dispersant on top of the crude oil. The conical flask was rotated on an orbital shaker for 10 mins and then allowed to rest for about 10 mins. The vial images were taken 30 min after stopping the LEDT test to determine the level of oil dispersed.
Efficiency measurement: EPA-approved baffled flask test (BFT) procedure was used to measure dispersion efficiency. Equivalent amounts of seawater, crude oil, and dispersant as above were added to 150 mL capacity conical flasks, followed by mixing for 10 minutes at 250 rpm. After a 10 minute break 30 mL of sample was taken from the middle of the water column and placed in a separatory funnel. Oil was extracted with the use of dichloromethane (DCM). The concentration of oil in the organic layer was determined with the use of a UV−vis spectroscopy on a Varian Cary 50 spectrophotometer.
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