Field Scale Test Protocol for Type I Sorbents

For small spill events (< 100 L) or during the final stages of spill cleanup efforts, sorbents are often deployed as a means of collecting spilled crude oil for later disposal. Effective sorbents for oil spill response are both oleophilic (attracting oil), and hydrophobic (repelling water), allowing pore spaces to collect and retain oil without the volume being decreased by entrained water. Understanding the performance and capacity of sorbents is necessary for determining how much to deploy for a given volume of oil, and under what conditions. The Field Scale Test Protocol for Type I Sorbents project sought to establish a new standard protocol for the testing of absorbent properties of sorbent materials in relevant environments and conditions. This initiative was built upon previously established laboratory protocols used to test sorbent materials. ASTM Protocol F726 (2024) is a current standard test for Type I sorbents, but the protocol has raised concerns of issues of scaling, due to the use of small sorbent sample coupons for testing, rather than full manufactured sorbent sheets. Smaller test coupons have the potential of artificially modifying the sorbent performance, by potentially modifying the inherent variability of the manufactured sorbent as well as changing the functionality of sorbent edges where the samples are cut. The current protocol also tests samples in static conditions, as opposed to the dynamic conditions expected during marine spills. The goal was to develop a reliable and repeatable testing method that could be universally applied across various facilities, with minimal cost for additional equipment for testing. This work was performed under a contract with S.L. Ross Environmental Research Limited, valued at $149,700.

The initial stage of the project focused on a complete evaluation of historic and established protocols related to the testing of sorbents. This literature review allowed for an evaluation of the unique and valuable techniques that could be incorporated into the final protocol. After the initial research stage, a team of experts from a variety of oil spill related organizations were convened to provide input on a draft protocol, done through industry meetings, workshops and private consultation. A demonstration of the draft protocol was conducted at Ohmsett with a team of researchers to observe the protocol in action and identify potential points of error in the current protocol. The demonstration provided researchers with a chance to observe equipment used at Ohmsett to represent dynamic ocean conditions in a laboratory setting, and to observe data collection techniques. The feedback from the Ohmsett demonstration was used to edit the draft protocol. An updated draft protocol was submitted to ASTM International F20.22 subcommittee for review and consideration under Work Item ID WK100266.

The protocol consists of testing full Type I sorbent sheets in a 1 m2 test chamber. The chamber is filled with 5 cm of water and agitated at 60 cycles per minute with 2.5 cm of horizontal amplitude for 60 minutes. Sorbents are tested with and without oil, to evaluate both oil and water uptake. For tests with oil, 5 L of oil are added to establish an oil depth of 5 mm across the water surface prior to agitation. Each sorbent must be massed prior to testing. After the test period, the sorbent is raised by clamps on the top edge of the sheet and allowed to drain for a set period depending on the test oil. After draining, the sample is massed, and the difference in mass is used to determine the mass of sorbed product. Sorbents are identified as failing the protocol if the sheets sink below the water surface during testing, or if sorbents rip or tear during the extraction or draining steps. This protocol serves as an effective means of testing Type I sorbents at full scale in a representative environment, while being cost effective and practical for a variety of test facilities. Testing sorbents with this protocol will be useful for providing spill responders with an accurate estimate of the capabilities and performance of Type I sorbents in marine spill environments.