Formation of oil-particle aggregates: Particle penetration and impact of particle properties and particle-to-oil concentration ratios

Post-Formation of Oil Particle Aggregates: Breakup and Biodegradation

“…Then, crude oil was added in the three sets at 500 mg/L using a positive displacement pipet. The flasks were then sealed and placed in an orbital shaker (Thermo Scientific MaxQ 2000, MA, US) at 200 rpm, thus providing a flask-averaged energy dissipation rate (ε) of 0.5 W/kg . Such a mixing energy is comparable to other experimental work , and was found to be the dominant mechanism for OPA formation as discussed in Ji et al…”

“…The flasks were then sealed and placed in an orbital shaker (Thermo Scientific MaxQ 2000, MA, US) at 200 rpm, thus providing a flask-averaged energy dissipation rate (ε) of 0.5 W/kg. 46 Such a mixing energy is comparable to other experimental work 53,54 and was found to be the dominant mechanism for OPA formation as discussed in Ji et al 47 Table 1 lists the experiments conducted at different mixing durations, whereby the flasks mixed for a short period (i.e., 0.5 to 24 h) were prepared in a series of four and were only used to investigate OPA breakup and formation, while the ones mixed for longer periods (96 to 672 h) were prepared in a series of seven, of which three were used for analyzing the biodegradation of petroleum hydrocarbons and four were used to investigate OPA breakup and formation. In addition, two sets of control flasks were prepared, in triplicate, to investigate the biodegradation and evaporation of crude oil while subject to the same conditions without adding sediments.…”

“…Generally, using fine sediments to disperse marine oil spills is promising, , but there are some concerns that the dense mineral materials (density ∼2000 kg/m 3 ) could sink after OPA formation, , which is even more harmful to the benthic biota than suspended or dispersed oil. , OPAs usually settle since they are mainly in the form of a Pickering emulsion ,, or large sediments covered with oil. , Nevertheless, Zhao et al reported that when plate-shaped kaolinite interacts with oil, the particles penetrate the oil droplets, resulting in further breakup. This was further investigated by Ji et al, , using a more hydrophobically modified kaolinite under higher mixing energy, in which the penetration depths significantly increased, resulting in the breakup of formed OPAs at a faster rate. The formation of such small OPAs (<20 μm), with a diameter similar to that of chemically dispersed oil droplets, increases the surface interaction between the petroleum hydrocarbons and the indigenous microorganisms, thereby enhancing the oil’s microbial degradation.…”

An experimental and modeling study on the penetration of spilled oil into thawing frozen soil

“…The size distribution was heterogenous and both fine and larger particles were present, leading to different amounts of oil in samples with the same mass, and thus the sample extraction 10% location and many other factors could also affect the results. 30 However, some regular patterns can still be obtained. For the 5 °C and 5 min thawing process, in which there was no ice content or ice converting to water rapidly, the oil penetrated into the deeper layer.…”

An experimental Stommel Retention Zone facility with an application to oil droplet dispersion

“…By reversing the belt direction to create a central upwelling region, the suspension of sediments can also be studied. Experiments with both oil droplets and sediments can also be performed to study the formation of OPAs (Boufadel et al 2019; Ji et al 2021). In addition, our experimental facility can serve as a tool for validating multiphase computational models of particle behavior in Langmuir cells.…”