Microcrystalline cellulose effects on the rheology of mixed oleogels structured with candelilla wax and saturated fat

The structuration processes of mixed oleogels produced with candelilla wax (CW, 0 or 3%), fully hydrogenated soybean oil (FH, 5-15%), and microcrystalline cellulose (MC, 0-9%) were studied to define their rheological effects. During the cooling CW crystals performed as nucleation sites for FH. The elastic modulus (G’) of oleogels with FH and 3% CW were more than two orders of magnitude higher than those produced with 0% CW. Adding MC to the oleogels increased slightly the G’. Independently of the amount of MC, oleogels structured with increasing amounts of FH and 0% CW showed the elastic properties scaling of colloidal gels. This behavior was lost by adding 3% CW, implying that in mixed FH-CW oleogels, the CW crystal network dominated the oleogel rheology. The flow point and the mechanical reversibility of oleogels and commercial butter (CB) was also determined. CB showed flow points at 44 and 59% strain and mechanical reversibility values of 29 and 35% of G’ measured in a pre-shear step. Adding MC to oleogels structured with FH and 0% CW increased their flow point (37.2%) near those of CB. This effect was not produced in mixed FH-3% CW oleogels. The mechanical recovery of oleogels produced with FH, MC, and 0% CW tend to decrease as the FH content increased. CW and MC did not show a simple concentration–effect relationship for the mechanical recovery. Nonetheless, oleogels structured with 3% CW and 10% FH and 6-9% MC showed mechanical recovery (~60%) close to that of CB.

Bubbler System Testing in Controlled Environment for Harsh Environment Oil Spill Recovery

Mechanical recovery techniques are used to clean up oil spills in marine environments; however, their efficiency is challenged when dealing with heavy oil, ice covered water and high sea states. Current mechanical recovery techniques are based on removing oil from the water surface, however, a significant amount of oil could remain in the water column below the surface due to turbulent ocean conditions, the density of heavy oil and oil escaping underneath the booms when the sweeping speed increases. To enhance the oil recovery effectiveness, oil particles in the water column need to be guided to the surface to be recovered by the skimmers. This paper focusses on the development of a test protocol and physical testing in C-CORE’s lab of a bubbler system for enhancing the harsh environment oil spill recovery. Air bubbles produce an upward flow in the water body, which guides the submerged particles to the surface. The air bubbles also attach to the oil particles, leading to an increase in the buoyancy and rate at which oil droplets rise to the surface. By adopting this technique for oil recovery, additional oil particles can be brought to the surface. In the study, the bubbler system was tested in both stationary and advancing conditions with medium and heavy oils. The results of the stationary and advancing tests indicate that the oil recovery ratios can be significantly enhanced by using an optimized bubbler system. Different types and configurations of bubblers were tested by varying the airflow rates and bubbler advancing speeds to determine the optimal solution. The optimal bubbler system has been observed to enhance the recovery ratio from 41.5% to 84.8% with airflow rates ranging from 0.05 to 0.20 CFM/foot. Furthermore, the effective integration of the bubbler system with a mechanical recovery system, its deployment and retrieval in a near field condition were demonstrated during tests in an outdoor tank.

Development of the Inland Estimated Recovery System Potential (ERSP) Calculator

ABSTRACT Mechanical oil spill recovery response planning currently depends on an equation contained in regulations which assigns an oil removal capability value to an individual oil skimmer. The Effective Daily Recovery Capacity (EDRC) calculator, the current planning standard oil spill recovery planning calculation method, depends solely on a prescribed percentage of the skimmer's nameplate capacity. EDRC came under heavy scrutiny as an inadequate means for vessel and facility plan holders to calculate their oil spill equipment needs in the wake of the 2010 Deepwater Horizon incident. EDRC's calculation omitted factors such as the encounter rate and onboard storage of skimmers. These limitations led the Bureau of Safety and Environmental Enforcement (BSEE) to develop a new calculator called the Estimated Recovery System Potential (ERSP) calculator in collaboration with the United States Coast Guard (USCG). ERSP is an oil encounter rate-based calculator that evaluates mechanical recovery equipment as a complete “system” as opposed to focusing on an individual component such as the skimmer capacity or an intake pump. This calculator incorporated the previously neglected factors such as decreasing oil thickness over time, swath width of skimmers, speed of the skimmers relative to the oil spill, oil/water separability, pump rate, onboard fluid storage, and transition time. Although ERSP appears to significantly improve mechanical recovery planning for offshore and nearshore skimming operations, USCG recognized that it may not be applicable for the inland operating environments where large numbers of oil spills occur. The USCG Research and Development Center (RDC) initiated a project to conduct research into oil spill response planning factors for the inland operational environment. RDC and RPS Group (Project Team) interviewed numerous governmental, industry, and Oil Spill Removal Organization (OSRO) subject matter experts to gain a broad perspective on this tool, what factors were critical to include, and how best to implement the tool. These interviews and further research led to the creation of the Inland ERSP Calculator conceptual model. Employing a system-based approach, the conceptual model provides the relationship between these factors and the ways in which they contribute into the calculator's estimation of oil spill recovery capacity. The Project Team presents this Inland ERSP Calculator conceptual model as consideration for regulatory implementation as a planning tool. It may improve planning capabilities for oil spill events in inland environments.

Response Options for an Offshore Deepwater Blow-Out, A Generic Evaluation of Individual and Combined Response Strategies

The low oil recovery rates reported during Macondo (3–5% of the released oil) have caused discussions regarding the efficiency of mechanical recovery compared to other oil spill response options. These low recovery rates have unfortunately been used as reference recovery rates in several later modelling studies and oil spill response analysis. Multiple factors could explain these low rates, such as operational priorities, where dispersants and/or in situ burning are given priority before mechanical recovery; extended safety zones; availability of adequate equipment and storage capacity of collected oil; the number of units available; the level of training and the available remote sensing support to guide operations. This study uses the OSCAR oil spill model to simulate a deep-water oil release to evaluate the effect of different response options both separately and in combination. The evaluated response options are subsea dispersant injection, mechanical recovery, and a combination of these. As expected, Subsea Dispersant Injection (SSDI) was highly effective and resulted in a significant reduction in residual surface oil (8% of released oil volume, versus 28% for the non-response option, NR). However, using large offshore oil recovery systems also reduced residual surface oil with a similar amount (9% of released oil volume). These results deviate significantly from the efficiency numbers reported after the Macondo incident and from later modelling studies scaled after the Macondo recovery rates. The increased efficiency of mechanical reported in this study is mainly due to inclusion of updated descriptions of response capabilities, reduced exclusion zone, a more realistic representation of surface oil distribution and modelling of response units' interactions with oil, (efficient oil recovery only on thick parts of the oil slick). The response capabilities and efficiency numbers for the different response options used in this study are based on equipment specifications from multiple response providers and authorities (Norwegian Clean Seas organisation (NOFO), Oil Spill Response (OSRL), Norwegian Coastal Administration (NCA), US Bureau of Safety and Environmental Enforcement (BSEE) and others). These capabilities are justified by well-established contingency plans, offshore exercises and annual equipment performance testing with oil.

Dynamics and healing behavior of metallosupramolecular polymers

Self-healing or healable polymers can recuperate their function after physical damage. This process involves diffusion of macromolecules across severed interfaces until the structure of the interphase matches that of the pristine material. However, monitoring this nanoscale process and relating it to the mechanical recovery remain elusive. We report that studying diffusion across healed interfaces and a correlation of contact time, diffusion depth, and mechanical properties is possible when two metallosupramolecular polymers assembled with different lanthanoid salts are mended. The materials used display similar properties, while the metal ions can be tracked with high spatial resolution by energy-dispersive x-ray spectrum imaging. We find that healing actual defects requires an interphase thickness in excess of 100 nm, 10 times more than previously established for self-adhesion of smooth films of glassy polymers.