Recent advances in chemical and biological degradation of spilled oil: A review of dispersants application in the marine environment

Next-generation stimuli-responsive smart membranes: Developments in oil/water separation

Effective treatment of oil-contaminated wastewater is essential due to its severe environmental and health impacts. The membrane-based separation is cost-effective, energy-efficient, and eco-friendly; however, fouling has remained a pressing issue. Stimuli-responsive membranes, which adjust their pore structure and surface properties in response to external triggers such as light, pH, and temperature, offer enhanced fouling resistance and improved separation performance. This review provides a comprehensive analysis of stimuli-responsive membranes for oil/water separation, emphasizing the role of smart polymeric materials engineered for controllable separation processes. We critically assess the strengths of these advanced membranes, including their tuneable wettability and energy-efficient operation, while identifying key limitations such as long-term stability, response time, scalability, and cost-effectiveness. Furthermore, the review explores various polymer types, synthesis methods, and fabrication techniques, evaluating their effectiveness in separation applications. Finally, the review concludes by outlining the challenges and proposing future directions to enhance the performance of stimuli-responsive membranes. By offering valuable insights into the dynamic control of membrane structures and properties, this study aims to inspire the development of next-generation stimuli-responsive membranes, drive their commercialization, and promote sustainable water treatment solutions.

ZnAl-LDH/wood-based antifouling membranes for high-flux and efficient oil/water separation

An efficient and antifouling cutting-edge membrane was fabricated via growing hierarchical ZnAl-layered double hydroxides (LDHs) nanosheets on the wood template for enhanced separation of immiscible oil/water mixtures and emulsions. The retained vertical channels within the wood substrate facilitated impressive liquid flux, while the LDHs layer coated on the wood surface establishes a robust hydration layer that effectively repels oil droplets. The synergistic effect of these two elements enables efficient separation of immiscible oil/water mixtures and emulsions. The ZnAl-LDHs/wood membrane demonstrates a remarkable reduction in oil adhesion, achieving exceptional antifouling performance. This innovative membrane was adept at efficiently separating oil/water mixtures, exhibiting an impressive flux of 1.87 × 106 L·m-2·h-1 with a separation efficiency of 99 %. Furthermore, it successfully processes surfactant-free emulsions at a rate of 8279 L·m-2·h-1 (99.4 % efficiency) and surfactant-stabilized emulsions at 6850 L·m-2·h-1 (98.8 % efficiency). The current work combines natural wooden channel structures and hydration layers formed by superhydrophilic LDHs nanosheets, providing new novel insights and support for the development of highly efficient membranes with antifouling properties for oil/water separation.

Spontaneous Emulsification of Alkanes Monitored by Multiple Light Scattering

When propylene oxide/ethylene oxide (PO/EO) surfactants were initially placed in the oil phase, long-chain alkanes with poor water solubility were emulsified spontaneously upon contact with the aqueous phase. This formation of oil droplets under static conditions was monitored and the efficiency of spontaneous emulsification was quantified using multiple light scattering (MLS). The effect of the initial surfactant phase on the interfacial tension and moduli was investigated using an interfacial tensiometer. The utilization efficiency of the surfactant and energy under external energy inputs was compared by analyzing the droplet size of the emulsions using microscopic observation and dynamic light scattering. The surfactant with the highest efficiency of spontaneous emulsification could disperse crude oil, which was used to address crude oil spill incidents in cold marine environments. To the best of our knowledge, this is the first study to monitor spontaneous emulsification under static conditions using MLS. This spontaneous emulsification under static conditions depended on the spontaneous diffusion of the PO/EO surfactants from the oil phase into the aqueous phase and on their interactions with the oil molecules. The findings of this study provide insights into the application of MLS to monitoring spontaneous emulsification.

Perfluoroalkylated benzoic acid-based phase-selective supramolecular self-assembly system for dye removal

In this study, perfluoroalkylated derivatives of benzoic acid S-6 and O-6 were designed and synthesized as supramolecular gelators using a simple one-step method. Both S-6 and O-6 could form gels in various organic solvents. Notably, these compounds have potential applications in environmental remediation, with S-6 demonstrating significant promise for oil spill treatment. After five recycling cycles, the recovery rate of the gelation capacity for diesel oil remained above 90%. Xerogels derived from O-6 at a concentration of 5 wt% in pump oil effectively adsorbed Rhodamine B (RhB). The adsorption process primarily involved chemical adsorption, electrostatic interactions between the O-6 xerogel and the cationic RhB dye, as well as physical adsorption within the xerogel's pores. In summary, benzoic acid derivatives represent a kind of multifunctional, recyclable, and efficient materials.

Maintaining ocean ecosystem health with hydrocarbonoclastic microbes

Accidental spills and persisting hydrocarbon pollution caused by petroleum exploitation have deeply disrupted marine ecosystems, including those in the deep oceans and the Arctic Ocean. While physicochemical methods are available for emergency cleanup, microorganisms are ultimately responsible for mineralizing the hydrocarbons. The understanding of environmental effects on the composition and efficiency of hydrocarbon-degrading microbial communities has greatly improved current microorganism-based remediation strategies. This review summarizes recent findings on the physiology, metabolism, and ecology of marine obligate hydrocarbonoclastic microorganisms. Strategies for improved biotechnological solutions based on the use of hydrocarbon-degrading microbes are discussed for hydrocarbon remediation in marine water columns, sediments, beaches, and the Arctic.

Advanced magnetic nanospheres for oil pollutant management: Dual roles in emulsification and demulsification

Environmental contamination from oil spills and industrial oily wastewater poses significant ecological risks due to the persistence of harmful organic compounds. To address these challenges, magnetic composite nanospheres (CMNP@CHPEI) are systematically developed, with carboxylated Fe3O4 nanoparticles (CMNP) as the core and amphiphilic hyperbranched polyethyleneimine (CHPEI) as the decorated shell. These novel nanospheres combine the controllable size and magnetic responsiveness of "hard" magnetic nanomaterials with the structural complexity and functional diversity of "soft" hyperbranched polymers. This design allows for switching between emulsification and demulsification behaviors by regulating the size of the nanospheres and the amphiphilicity of CHPEI. Specifically, the nanospheres can form Pickering emulsions with oil droplet sizes smaller than 1 µm, maintaining stability for up to 75 days, and achieve rapid oil-water separation with demulsification efficiencies up to 99.8 %. Even after seven recycling experiments, they still retain significant interfacial activity and applicability. Interfacial characteristic experiments and molecular dynamics simulations reveal that particle size directly affects the film structures formed at oil-water interface, while the amphiphilic functional molecules determine the interaction mode of nanospheres with oil-water phases. These achievements introduce a versatile, environmentally friendly material for removing hazardous oil-based pollutants, with promising applications in oil spill remediation and industrial wastewater treatment.

Mapping of oil spills in China Seas using optical satellite data and deep learning

Oils spilled into the ocean can form various weathered oils (non-emulsified oil slicks (NEOS), oil emulsions (OE)) which threaten the oceanic and coastal environments and ecosystems. Optical remote sensing has the unique ability to discriminate oil types and quantify oil volumes as their spectral contrasts with oil-free seawater. Here, a deep learning-based model is developed for identification, classification, and quantification of various oil types. Based on the oil-contained datasets collected from 7 satellite sensors from April 2019 to August 2023, the origin, quantity, and spatial distribution of oils spilled from ships and rigs in the China Seas are mapped in detail. We found that oil spill incidents are primarily from ship discharges (85.8 %), while platform leaks lead to more oil emulsions (58.6 % compared to 13.1 % from ships), which illuminates that the drilling oils are the main source of oil spill pollution in China Seas. The spilled oils correlate with major port locations, including offshore Qingdao and Rongcheng, Bohai Bay, the adjacent areas of Beihai, and Hue and Danang in Vietnam. This study provides new insights into the assessment and management of offshore and marine oil spills.

A review of oil spill research in Canadian Arctic marine environments

The Canadian Arctic is a large and diverse geographic area that encompasses a wide variety of environmental conditions and ecosystems. Over recent decades, marine transportation has increased across the Arctic and, as a result, so has the likelihood of an oil spill. The study of oil spills in the Arctic presents unique challenges compared to temperate marine environments, due to remoteness, cold temperatures and the presence of snow and ice throughout much of the year. This review summarizes and discusses the fate of oil in the Canadian Arctic. A brief introduction to the Canadian Arctic and sources of potential petroleum spills is provided, followed by discussions of the behaviour of oil in ice and freezing temperatures, oil-sediment interactions, and the weathering and natural remediation of oil under Arctic conditions. A summary of perspectives concludes the review, with emphasis on possible areas of future work to address research gaps.

Efficient solar-driven crude oil cleanup via graphene/cellulose aerogel with radial and centrosymmetric design

Frequent oil spills pose significant threats to ecosystems; therefore, strict requirements are needed for prompt remediation and reclamation of spilled oil. Influenced by the structure of coniferous trees and their water transport, this experiment used cellulose nanofiber (CNF), polyvinyl alcohol (PVA), and methyltrimethoxysilane (MTMS) to prepare radially centrosymmetric aerogels. By utilizing the in-situ polycondensation reaction of MTMS, CNF, and PVA were connected, and the hydrophobicity and mechanical properties of the aerogel were greatly enhanced. Furthermore, the introduction of graphene oxide (GO), enshrouded within the cross-linked network, engenders heightened photo-thermal effects. The resultant composite aerogel exhibits expeditious oil absorption under solar irradiation and radial layered channel architecture, significantly curtailing the crude oil absorption timeframe (achieving a maximum absorption capacity of 51.7 g/g). Moreover, it demonstrates superior performance in rapidly and repeatedly adsorbing highly viscous crude oil, surpassing existing literature. Notably, continuous absorption of high-viscosity crude oil is achieved by integrating the composite aerogel with a peristaltic pump. This study offers a novel approach to the absorption and retrieval of high-viscosity crude oil, broadening the potential application horizons of CNF-based aerogels within environmental remediation.

The green tide causative-species Ulva prolifera responding to exposure to oil and dispersant

In order to study the role of oil spills in the occurrence of green tide in the Yellow Sea, the physiological characteristics and photosynthetic activities of green tide causative-species Ulva prolifera was monitored under different conditions including two oil water-accommodated fractions (WAFs) of diesel oil and crude oil, dispersed water-accommodated fractions (DWAFs) and dispersant GM-2. The results showed that, the physiological parameters of U. prolifera including the growth, pigment, carbohydrate and protein contents decreased with the increased diesel oil WAF (WAFDO) concentration, while crude oil WAF (WAFCO) showed low concentration induction and high concentration inhibition effect. In addition, with the increase of WAFs concentration, two antioxidant activities were activated. However, compared with WAFDO alone and WAFCO alone, the mixture of oil and dispersant enhanced the toxicity on the above physiological characteristics of U. prolifera. On the other hand, the photosynthetic efficiency of U. prolifera showed a similar trend. Two WAFs showed significant concentration effects on the chlorophyll-a fluorescence transients and JIP-test. The addition of dispersant further blocked the electron flow beyond QA and from plastoquinone (PQ) to PSI acceptor side, damaged the active OEC centers at the PSII donor side, suppressed the pool size and the reduction rate of PSI acceptor side, and reduced the energy transfer efficiency between PSII functional units. These results implied that the crude oil spills may induce the formation of U. prolifera green tide, and the oil dispersant GM-2 used after the oil spills is unlikely to further stimulate the scale of bloom, while the diesel oil spills is always not conducive to the outbreak of green tide of U. prolifera.

Assessment of spilled oil dispersion affected by dispersant: Characteristic, stability, and related mechanism

Oil dispersion, a crucial process in oil transport, involves the detachment of oil droplets from slicks and their introduction into the water column, influencing subsequent oil migration and transformation. This study examines oil dispersion, considering characteristics, stability, and mechanisms, while evaluating the impact of dispersants and salinity. Results show the significant role of surfactant type in dispersants on oil dispersion characteristics, with anionic surfactants exhibiting higher sensitivity to salinity changes compared to nonionic surfactants. The dispersion efficiency varies with salinity, with anionic surfactants performing better in low salinity (<20‰) and nonionic surfactants showing superior performance at 30-35‰ salinities. Rheological analysis illustrates the breakup and coalescence of oil droplets within the shear rates of breaking waves. An increase in interfacial film rigidity impedes the coalescence of oil droplets, contributing to the dynamic stability of the oil-water hybrid system. The use of GM-2, a nonionic dispersant, results in the formation of a solid-like interface, characterized by increased elastic modulus, notably at 20‰ salinity. However, stable droplet size distribution (DSD) at 35‰ salinity for 60 h suggests droplets can remain dispersed in seawater. The enhancement of stability of oil dispersion is interpreted as the result of two mechanisms: stabilizing DSD and developing the strength of viscoelastic interfacial film. These findings offer insights into oil dispersion dynamics, highlighting the importance of surfactant selection and salinity in governing dispersion behavior, and elucidating mechanisms underlying dispersion stability.

Modeling study on oil spill transport in the Great Lakes: The unignorable impact of ice cover

The rise in oil trade and transportation has led to a continuous increase in the risk of oil spills, posing a serious worldwide concern. However, there is a lack of numerical models for predicting oil spill transport in freshwater, especially under icy conditions. To tackle this challenge, we developed a prediction system for oil with ice modeling by coupling the General NOAA Operational Modeling Environment (GNOME) model with the Great Lakes Operational Forecast System (GLOFS) model. Taking Lake Erie as a pilot study, we used observed drifter data to evaluate the performance of the coupled model. Additionally, we developed six hypothetical oil spill cases in Lake Erie, considering both with and without ice conditions during the freezing, stable, and melting seasons spanning from 2018 to 2022, to investigate the impacts of ice cover on oil spill processes. The results showed the effective performance of the coupled model system in capturing the movements of a deployed drifter. Through ensemble simulations, it was observed that the stable season with high-concentration ice had the most significant impact on limiting oil transport compared to the freezing and melting seasons, resulting in an oil-affected open water area of 49 km2 on day 5 with ice cover, while without ice cover it reached 183 km2. The stable season with high-concentration ice showed a notable reduction in the probability of oil presence in the risk map, whereas this reduction effect was less prominent during the freezing and melting seasons. Moreover, negative correlations between initial ice concentration and oil-affected open water area were consistent, especially on day 1 with a linear regression R-squared value of 0.94, potentially enabling rapid prediction. Overall, the coupled model system serves as a useful tool for simulating oil spills in the world's largest freshwater system, particularly under icy conditions, thus enhancing the formulation of effective emergency response strategies.

Performance evaluation of rhamnolipid biosurfactant produced by Pseudomonas aeruginosa and its effect on marine oil-spill remediation

This study aimed to reveal that the effect of biosurfactant on the dispersion and degradation of crude oil. Whole genome analysis showed that Pseudomonas aeruginosa GB-3 contained abundant genes involved in biosurfactant synthesis and metabolic processes and had the potential to degrade oil. The biosurfactant produced by strain GB-3 was screened by various methods. The results showed that the surface tension reduction activity was 28.6 mN·m-1 and emulsification stability was exhibited at different pH, salinity and temperature. The biosurfactant was identified as rhamnolipid by LC-MS and FTIR. The fermentation conditions of strain GB-3 were optimized by response surface methodology, finally the optimal system (carbon source: glucose, nitrogen source: ammonium sulfate, C/N ratio:16:1, pH: 7, temperature: 30-35 °C) was determined. Compared with the initial fermentation, the yield of biosurfactant increased by 4.4 times after optimization. In addition, rhamnolipid biosurfactant as a dispersant could make the dispersion of crude oil reach 38% within seven days, which enhanced the bioavailability of crude oil. As a biostimulant, it could also improve the activity of indigenous microorganism and increase the degradation rate of crude oil by 10-15%. This study suggested that rhamnolipid biosurfactant had application prospect in bioremediation of marine oil-spill.

EOS - Environment & Oil Spill Response. An analytic tool for environmental assessments to support oil spill response planning: Framework, principles, and proof-of-concept by an Arctic example

The Environment & Oil Spill Response tool (EOS), supports oil spill response planning and decision making. This tool is developed on a research basis, and is an index based, generic and open-source analytic tool, which environmentally can optimise the choice of oil spill response methods for a given spill situation and for a given sea area with respect to environment and nature. The tool is not linked to a particular oil spill simulation model, although it is recommended using oil spill simulation models to have detailed data available for the analysis. The EOS tool consists of an Excel workbook with formulas for calculations and scores followed by screening through decision trees. As case for the EOS tool proof-of-concept, the area of Store Hellefiskebanke, West Greenland, is used. The tool can be downloaded from the Aarhus University home page as a free-of-charge application and is accompanied by a handbook for guidance.

Hydrophobic organogel sorbent and its coated porous substrates for efficient oil/water emulsion separation and effective spilled oil remediation

Frequent offshore oil leakage accidents and large quantities of oily-wastewater produced in industry and daily life bring huge challenges to global water purification. The adaptability and stability of organogels as adsorbent materials have shown wide application prospects in the field of oil-water separation. Herein, the organogels displayed stable hydrophobic/lipophilic properties with high absorption ability (1200 wt./wt%), efficient sorption of multiple emulsions (>99.0%), and good reusability. More importantly, the organogels were successfully assembled with 2D/3D substrates to achieve excellent sorption capacity (102.5 g/g) and recycling performance (50 cycles). The gel-carbon black assembled on MS (GCB-MS) sorbent with excellent photothermal conversion performance, and can rapidly heat the surface to 70.4 °C under 1.0 sunlight radiation (1.0 kW/m2) and achieved an ultra-high sorption capacity of about 103 g/g for viscous crude oil. Meanwhile, the GCB-MS was combined with a pump to build continuous oil spill cleaning equipment to achieve a super-fast cleanup rate of 6.83 g/min. The developed hydrophobic organogels had been expanded unprecedentedly to realize the comprehensive treatment of oily-wastewater in complex environments, including layered oils, emulsions, and viscous crude oil spill, which provided an effective path for the comprehensive treatment of oily wastewater in complex environments.

Dispersant-enhanced photodissolution of macondo crude oil: A molecular perspective

Previous laboratory studies developed a conceptual model based on elevated non-volatile dissolved organic carbon (NVDOC) concentrations after photodegradation and subsequent dissolution of Macondo oil following the Deepwater Horizon blowout. However, those experiments did not account for the effects of ∼1 million gallons of dispersant applied to the surface oil. Here, laboratory results show photodissolution in the presence of dispersant results in > 2x increase in NVDOC concentrations after extensive photoprocessing relative to oil without dispersant. This result corresponds with an apparent increase in the percentage of surface oil photodissolution from approximately 4% in the absence of dispersant to 7% in the presence of dispersant. The oil and dissolved products were analyzed by excitation-emission matrix spectroscopy and ultrahigh resolution mass spectrometry. The compounds that persisted in the oil phase are relatively aromatic without dispersant, while those in the presence of dispersant are highly aliphatic, paraffinic, wax-like compounds. The composition of the dissolved compounds produced from both treatment types are nearly identical after 240 h of exposure to simulated sunlight. The NVDOC and chemical composition information indicate that the photodissolution of MC252 oil in the presence of dispersant is enhanced and accelerated, suggesting that the effects of dispersants should be included in mass transfer calculations from the oil to the aqueous phase.

Design and evaluation of a sustainable entropy-weighted and VIKOR-based method for offshore oil collecting

With the expansion of marine oil exploitation, offshore oil leakage has become an urgent problem that cannot be ignored in marine ecological protection. To address the problem, this paper proposes a comprehensive design and evaluation approach aiming at the design of offshore oil collection. This approach combines the entropy weight and VIKOR method with three principles of sustainable design. Specifically, to establish the evaluation model, this paper transforms these principles of sustainability into three aspects of practicality, economy, and environmental protection, thus constructing a multi-level evaluation index system. Subsequently, entropy weights are then used to decline the one's own element in the decision maker's weights. Besides this, the VIKOR method is applied to acquire the optimal ranking of design alternatives for offshore oil collection to choose the optimal product design strategy. According to the obtained experimental results, the proposed design method combining the entropy weight and the VIKOR method is feasible and reasonable. To be exact, it improves the comprehensive index of the product in the design concept stage by over 20%, and it effectively optimizes the resource allocation of the design process.

MXene/Graphene modified cellulose aerogel for photo-electro-assisted all-weather cleanup of high-viscous crude oil from spill

The frequent occurrence of oil spills has led to serious environmental pollution and ecological issues. Given the high-viscosity of crude oil, it is essential to develop sorbents with efficient viscosity reduction and sorption capacity in various environmental conditions. Herein, a superhydrophobic carboxymethyl cellulose (CMC) aerogel co-modified by MXene and graphene jointly (M-Mxene/Gr CA) with aligned channels structure was prepared. The aligned channels structure can effectively improve the longitudinal thermal conductivity and reduce the sorption resistance. Through the modification of MXene and graphene, the aerogel realized efficient photo/electro-thermal conversion, thus ensuring its adaption to various working environments. The rapid heat generation can significantly reduce the viscosity of crude oil, achieving rapid recovery. Under one sun illumination (1.0 kW/m2), the surface temperature of M-Mxene/Gr CA can reach 72.6 °C and its sorption capability for high-viscous crude oil reaches 18 g/g. Combining photo-thermal and electro-thermal (0.5 kW/m2 and 23 V), the average sorption rate of crude oil can reach 1.3 × 107 g m-3 s-1. Finally, we present a continuous sorption system to recover offshore oil spills under the assistance of a pump. This work provides a new option for tackling high-viscous offshore oil spills due to its environmental friendliness and fast sorption capacity.

Applications of bubble curtains in marine oil spill containment: Hydrodynamic characteristics, applications, and future perspectives

Although the marine oil spill pollution issue does not bring us to flock in droves as the new emerging oceanic techniques like wave energy converters, remote operated vehicle (ROV), blue ammonia and green hydrogen, the huge pollution risks of the marine oil spills caused by man-made intentional discharge, old equipment, accidental leakage, war and other aspects should arouse our sufficient attention and concern. As the primary countermeasure of emergency response to a marine oil spill, rapid & efficient oil containment is crucial to limit the pollution scope and the subsequent recovery and treatment. Here, we summarized the existing investigations on oil-spill containment with a marked emphasis on the applications of bubble curtains and their working mechanisms. The critical research progress and trends about the remediation techniques and the application of bubble curtains in marine environments were briefly introduced. The article thoroughly analyzed the basic working mechanism of the bubble curtains in oil spill containment, the technical difficulties of the existing methods, the potential application prospects of coupling with the traditional oil containment booms and the critical scientific problems to be studied in the future. Regarding the issues involving insufficient oil retention performance and inconvenient deployment of the existing traditional oil boom under complex and variable sea conditions, the performance and structural optimization of bubble curtain enhanced oil containment boom will get the top priority in developing the next-generation oil containment techniques.

Constructing a highly tough, durable, and renewable flexible filter by epitaxial growth of a glass fiber fabric for high flux and superefficient oil-water separation

The separation and purification of complex and stable stubborn oily sewage is extremely challenging. To respond to this challenge, we developed a powerful flexible filter with ultrahigh strength, durability, flux, separation efficiency, and a multiobjective separation function based on a universal epitaxial growth process of glass fiber fabric (Gf). The underwater oil contact angle (UOCA) of the silicate@Gf (MgSi@Gf) filter is 156.3°, so it can achieve both an ultrahigh permeation flux (5632.7 L·m^-2·h^-1) and oil-water separation efficiency (99.5%) under gravity (≈ 1 kPa) in purifying surfactant-stabilized emulsions, actual industrial oily sewage and mechanical cold rolling emulsions. The filter with a high tensile strength (66.5 MPa) and oil invasion pressure (4626 Pa) can withstand the impact of much sewage or intense water flow. The filter can tolerate extreme conditions and can maintain high separation performance in acid or alkaline (pH 1-13), high or low temperature (100 °C, 200 °C, -18 °C) conditions or natural salty waters such as seawater. The filter can remove methylene blue (MB) dye (99.8%) by filtration, and can be repeatedly and easily reconstructed (renewable advantage). The filter shows great potential for efficiently eliminating the hazards of contaminants in actual oily sewage and thus protect human health.

Transport of Microplastic and Dispersed Oil Co-contaminants in the Marine Environment

Microplastics (MPs) and oil pollution are major concerns in oceans. Although their coexistence in oceans and the associated MP-oil-dispersant agglomerates (MODAs) have been reported, limited attention is given to the behavior of the co-contaminants. This study investigated MODA transport in a simulated ocean system and explored related mechanisms under various oil types, salinities, and mineral concentrations. We found that more than 90% of the heavy oil-formed MODAs stayed at the seawater surface, while the light oil-formed MODAs were widely distributed throughout the seawater column. The increased salinity promoted MODAs formed by 7 and 90 μm MPs to transport from the seawater surface to the column. This was elucidated by the Derjaguin-Landau-Verwey-Overbeek theory as more MODAs formed under higher salinities and dispersants kept them stable in the seawater column. Minerals facilitated the sinking of large MP-formed MODAs (e.g., 40 μm) as minerals were adsorbed on the MODA surface, but their impact on small MP-formed MODAs (e.g., 7 μm) was negligible. A MODA-mineral system was proposed to explain their interaction. Rubey's equation was recommended to predict the sinking velocity of MODAs. This study is the first attempt to reveal MODA transport. Findings will contribute to the model development to facilitate their environmental risk evaluation in oceans.

Magnetic, self-heating and superhydrophobic sponge for solar-driven high-viscosity oil-water separation

In this work, a novel oil-adsorption sponge with superhydrophobicity was fabricated using polymer-assisted electroless deposition and dip-coating techniques for depositing a rough polydopamine layer, magnetic particles, and low surface energy polydimethylsiloxane onto the surface of a sponge skeleton. The as-prepared superhydrophobic sponge (WCA > 150° and SA < 5°) exhibited rapid adsorption behavior, large adsorption capacity (up to 50.6 times its own dry weight or above 90% of its own volume), excellent durability (above 80% of the adsorption capacity after 80 recycles), and a self-cleaning property owing to sufficient open-cell pores and superelasticity provided by the melamine-formaldehyde host as well as the hierarchical roughness and convenient magnetic recovery enabled by the polymer-assisted electroless deposition approach. The pump-, gravity-, and solar-driven oil-water separation devices based on the fabricated cubic composites were also demonstrated, particularly the separation of high-viscosity oil-water mixtures via the solar-driven mode, demonstrating the broad prospects of such modified sponges in actual applications. This study provides a new avenue for rationally designing novel oil adsorption and separation materials.

Superhydrophobic polyurethane sponge for efficient water-oil emulsion separation and rapid solar-assisted highly viscous crude oil adsorption and recovery

Rapid and efficient cleaning of oily wastewater and high viscosity crude oil spills is still a global challenge. Conventional three-dimensional porous adsorbents are ineffective for oil-water separation in harsh environment and are restricted to the low fluidity of high viscosity crude oil at room temperature. Increasing temperature can enormously improve the fluidity of viscous crude oil. Herein, the polydimethylsiloxane (PDMS) /carbon black (CB) -modified polyurethane sponge (PU) were prepared by a simple one-step dip-coating method. PDMS/CB@PU (PCPU) exhibits high adsorption capacity to various oils and organic liquid (28.5-68.7 g/g), strong mechanical properties (500 cycles at 50%), outstanding reusability (100 cycles of adsorption and desorption) and excellent environmental stability due to the special PDMS/CB coating. The maximum surface temperature of PCPU sponge can reach 84.7 ℃ under 1 sunlight irradiation. Therefore, the PCPU sponge can rapidly heat and enhance the fluidity of viscous crude oil, significantly speeding up the viscous oil recovery process with the maximum adsorption capacity of 44.7 g/g. In addition, the PCPU sponge can also combine with the vacuum pump to realize the continuous and rapid repair of viscous oil spills from the seawater surface. In consideration of its simple preparation, cost-effectiveness and high oil absorption ability, this solar-assisted self-heating adsorbent provides a new direction for large-scale cleanup and recycling of viscous crude oil spill on the seawater surface.

Biodegradation of oil-contaminated aqueous ecosystem using an immobilized fungi biomass and kinetic study

Remediation of environmental oil pollution with the usage of fungal organisms has proven to be a successful cleanup bioremediation method for organic contaminants. To investigate the breakdown of oil pollutants in water environments, biosurfactant-producing fungi have been isolated from oil-polluted soil samples. 16s rRNA sequencing technique was performed to identify the fungal organism and phylogenetic tree has been constructed. A variety of biosurfactant screening tests have demonstrated the better biosurfactant producing ability of fungi. The emulsion's stability, which is essential for the biodegradation process, was indicated by the emulsification index of 68.48% and emulsification activity of 1.3. In the isolated biosurfactant, important functional groups such as amino groups, lipids, and sugars were found according to thin layer chromatography analysis with a maximum retention value of 0.85. A maximum oil degradation of around 64% was observed with immobilized beads within 12 days. The half-life, and degradation removal rate constant of 20.21 days and 0.03 day^-1, respectively, have been determined by the degradation kinetic analysis. GCMS analysis confirmed the highly degraded hydrocarbons such as nonanoic acid and pyrrolidine. The immobilized fungi exhibit better oil biodegradability in aqueous solutions.

PAH depletion in weathered oil slicks estimated from modeled age-at-sea during the Deepwater Horizon oil spill

During time-periods oil slicks are in the marine environment (age-at-sea), weathering causes significant changes in composition and mass loss (depletion) of oil spill chemicals including the more toxic polycyclic aromatic hydrocarbons (PAHs). The goal of this study was to estimate the age-at-sea of weathered oil slicks using the oil spill module of the Connectivity Modeling System and to use this age to interpret PAH concentration measurements. Percent depletion (PD) for each measurement was computed as the percentage difference between the original and measured PAH concentration in the crude oil and weathered oil slicks, normalized upon the mass losses relative to hopane. Mean PD increased with estimated age-at-sea for all PAHs. Less PD was observed for alkylated than for parent PAHs, likely due to decreasing vapor pressure with increasing degree of alkylation. We conclude that estimated age-at-sea can be used to explain PAH depletion in weathered oil slicks. We propose PAH vapor pressure can be coupled with the model to expand capacity for predicting concentration distributions of individual parent and alkylated PAHs in weathered oil along the coastline. This new module will advance the science supporting oil spill response by providing more certain estimates of health risks from oil spills.