Development of a testing protocol for oil solidifier effectiveness evaluation

Chemical countermeasures for oil spill remediation have to be evaluated and approved by the U.S. Environmental Protection Agency before they may be used to remove or control oil discharges. Solidifiers are chemical agents that change oil from a liquid to a solid by immobilizing the oil and bonding the liquid into a solid carpet-like mass with minimal volume increase. Currently, they are listed as Miscellaneous Oil Spill Control Agent in the National Contingency Plan and there is no protocol for evaluating their effectiveness. An investigation was conducted to test the oil removal efficiency of solidifiers using three newly developed testing protocols. The protocols were qualitatively and quantitatively evaluated to determine if they can satisfactorily differentiate effective and mediocre products while still accounting for experimental error. The repeatability of the three protocols was 15.9, 5.1, and 2.7 %. The protocol with the best performance involved measuring the amount of free oil remaining in the water after the solidified product was removed using an ultraviolet–visible spectrophotometer and it was adopted to study the effect of solidifier-to-oil mass ratio, mixing energy, salinity, and beaker size (i.e., area affected by the spill) on solidifier efficiency. Analysis of Variances were performed on the data collected and results indicated that the beaker size increased spreading, which reduced removal efficiency. Mixing speed appears to impart a ceiling effect with no additional benefit provided by the highest level over the middle level. Salinity was found to be mostly an insignificant factor on performance

Characterization of solidifiers used for oil spill remediation

The physical characteristics and chemical composition of oil spill solidifiers were studied, and correlation of these properties with product effectiveness enabled determination of characteristics that are desirable in a good solidifier. The analyses revealed that the commercial products were primarily comprised of organic polymers and a few trace elements. A natural sorbent, which was composed entirely of plant based matter, was also evaluated, and it had the highest oil removal capacity, but it did not produce a solid mat-like final product. Generally, solidifiers with a carbonate group, pore size greater than 5 mum, and bulk densities lower than 0.3 g cm(-3) were found to have better efficiency and produced a cohesive rubbery final product that facilitated removal compared to sorbents. The importance of bulk density and pore size in the performance of the solidifier suggest that the primary mechanism of action was likely physical sorption

Parametric study to determine the effect of temperature on oil solidifier performance and the development of a new empirical correlation for predicting effectiveness

Temperature can play a significant role in the efficacy of solidifiers in removing oil slicks on water. We studied and quantified the effect of temperature on the performance of several solidifiers using 5 different types of oils under a newly developed testing protocol by conducting experiments in constant temperature rooms set at 22. °C and 5. °C. The results indicated that solidifier efficiency decreased substantially at the lower temperature, especially at lower application rates. The removal efficiency of the solidifier was in general directly proportional to temperature, except for the heavier oils, where removal by attachment was observed. Solidifier products with lower powder bulk density exhibited the best removal effectiveness. Analysis of experimental data yielded empirical correlations involving certain operational variables such as application rate, temperature, solidifier property (bulk density), and oil property (viscosity). Regression analysis was used to fit a mathematical model to the experimental solidifier effectiveness data. © 2015 Elsevier Ltd

Effect of Salinity on the Effectiveness of Solidifiers for Crude Oil Spill Remediation

ABSTRACT A laboratory investigation was conducted to test the effectiveness of solidifiers with fresh water and artificial seawater using Prudhoe Bay Crude oil. Experiments were designed to study the effects of salinity, solidifier type, solidifier-to-oil mass ratio (SOR), mixing energy and beaker size using five solidifiers. The U.S. Environmental Protection Agency is developing a protocol for testing the effectiveness of solidifiers in a laboratory setting. This involves measuring the amount of free oil remaining in the water after the solidified product is removed using an ultraviolet–visible spectrophotometer. For these experiments, 0.25 mL of oil was added to salinized beaker containing 80 mL of water. Milli-Q water and sterile GP2 seawater were used as the exposure media. The mass of the solidifier was changed depending on the SOR. Each of the solidifier was added to a slick of crude oil on water. After stirring the mixture for 30 minutes, the solidifier was removed. The water with the remaining oil was transferred from the beaker to 250 mL separatory funnel. The solution in the funnel was extracted three times with 20 mL of dichloromethane and the final volume adjusted to 60 mL. The extracted samples were analyzed for oil content with an Agilent 8452 ultraviolet–visible spectrophotometer. All experiments were carried out in triplicate. An analysis of variance (ANOVA) was performed on the data collected, which helped quantify the main and interactive effects of the variables. Salinity of the water was mostly found to be an insignificant factor. Results indicated that SOR and solidifier type are the most important variables affecting removal efficiency.</jats:p