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.

Joule Heating-Assisted Crude Oil Purification by a Poly(pyrrole)-Modified Microfibril Cellulose Membrane.

Using membrane materials to purify viscous watery oil from industrial production processes and accidental oil spills is of great importance but still challenging. Based on the excellent electrical conductivity and electric-thermal conversion of poly(pyrrole) (PPy), a hydrophobic PPy-modified micro-fibrillated cellulose membrane (P-CP) was successfully prepared. The size of the P-CP membrane can be customized to meet specific requirements. In this research, the membrane diameter is capable of reaching 24 cm. By applying a voltage ranging from 0 to 12 V, the surface temperature of the P-CP membrane can be elevated to roughly 120 °C. After 10 cycles of heating and cooling under 12 V voltage, the electric-thermal curves, surface hydrophobicity, and pore structure of P-CP membrane can remain stable, which suggests remarkable electric-thermal stability and reliability despite prolonged operation. The P-CP membrane shows good linearity between voltage and current (R2 = 0.997) and easy temperature control from room temperature to ∼120 °C at low supply voltage (0-12 V). Under the condition of 12 V power supply and self-gravity, the separation flux of the P-CP membrane for water-in-oil (W/O) emulsions (kerosene, diesel) is 2-3 times higher than that at room temperature, and the separation efficiency is also improved. Importantly, the P-CP membrane shows excellent separation performance for high viscosity water-in-crude oil emulsions, with a separation flux of 40 L m-2 h-1 by gravity. Compared to the situation without electricity, the separation flux of water-in-crude oil emulsion has increased four-fold. The joule heating of the P-CP membrane expands its service time and application scenarios, demonstrating its great application prospects in actual viscous oil-water emulsion separation.

Mechanism of nearshore sediment-facilitated oil transport: New insights from causal inference analysis.

A quantitative understanding of spilled oil transport in a nearshore environment is challenging due to the complex physicochemical processes in aqueous conditions. The physicochemical processes involved in oil sinking mainly include oil dispersion, sediment settling, and oil-sediment interaction. For the first time, this work attempts to address the sinking mechanism in petroleum contaminant transport using structural causal models based on observed data. The effects of nearshore salinity distribution from the estuary to the ocean on those three processes are examined. The causal inference reveals sediment settling is the crucial process for oil sinking. Salinity indirectly affects oil sinking by promoting sediment settling rather than directly affecting oil-sediment interaction. The increase of salinity from 0‰ to 35‰ provides a natural enhancement for sediment settling. Notably, unbiased causal effect estimates demonstrate the strongest positive causal effect on the settling efficiency of sediments is posed by increasing oil dispersion effectiveness, with a normalized value of 1.023. The highest strength of the causal relationship between oil dispersion and sediment settling highlights the importance of the dispersing characteristics of spilled oil to sediment-facilitated oil transport. The employed logic, a data-driven method, will shed light on adopting advanced causal inference tools to unravel the complicated contaminants' transport.

An S-scheme NH2-MIL-101(Fe)@MCN/Bi2O3 heterojunction photocatalyst for the degradation of tetracycline and production of H2O2.

Effective and durable photocatalysts are essential for the decomposition of persistent contaminants and the generation of hydrogen peroxide. In this study, we successfully constructed an S-type heterojunction by in situ growing Bi2O3 nanocrystals and NH2-MIL-101(Fe) onto surface-modified g-C3N4. The process of charge transfer in the S-type heterojunction was confirmed using ISI-XPS, DFT calculations, capture experiments, and EPR signals. The combined influence of the heterojunction and MOF demonstrated remarkable photocatalytic performance in the breakdown of tetracycline (TC) and the generation of hydrogen peroxide (H2O2). In the enhanced setup (10%-NH2-MIL-101(Fe)@MCN/Bi2O3), full degradation of TC was accomplished within 50 min under visible light exposure. Additionally, a notable H2O2 yield of 655.63 µmol/g was attained, all achieved without the necessity of sacrificial agents or supplementary oxygen. Based on the outcomes of the dual functionality, the exceptional performance of the ternary composite material can be ascribed to the collaborative influence of the heterojunction and MOF. This collaborative effect expands the light absorption range in the visible region, suppresses the recombination of electron-hole pairs, and enhances the photocatalytic redox ability. The system demonstrates significant potential in the efficient in situ production of H2O2 and removal of recalcitrant organic pollutants in pure water.

Melt-blown fiber felt for efficient all-weather recovery of viscous oil spills by Joule heating and photothermal effect.

Adsorbents play a vital role in responding to marine oil spills, yet effectively cleaning up viscous oil spills remains a technical challenge. Herein, we present a superhydrophobic oil-adsorbing felt prepared using melt-blown technology and functionally enhanced with a photoelectric composite CNT/PANI coating for effectively cleaning up high-viscosity oil spills. By virtue of its superior solar/Joule heating ability and thermally conductive fiber network, p-CNT/PANI@PP notably reduced crude oil viscosity and enhanced the oil diffusion coefficient within pores. Leveraging primarily solar heating and supplemented by Joule heating, p-CNT/PANI@PP demonstrates an impressive in-situ adsorption rate of up to 560 g/h for ultra-high-viscosity crude oil (c.a. 138000 mPa·s), alongside an adsorption capacity of 15.57 g/g. This measure enables efficient viscosity reduction and continuous day-and-night recovery of viscous crude oil, addressing the challenges posed by seasonal fluctuations in seawater temperature and adverse weather conditions. Moreover, a conveyorized collector integrated with an oil-adsorbing felt realizes continuous recovery of viscous oil spills with speed control to tackle varying thicknesses of oil film. Given the top-down material design, superior functionality, and applicability to applications, this work provides a comprehensive and feasible solution to catastrophic large-area viscous oil spills.

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.

Aluminum soap nanoparticles-lignin powder form phase-selective gelator as an efficient sorbent for oils/water separation.

Rapid and efficient recovery of oil spill is the key link for oil spill remediation, and also a great challenge. Here, the organogelator-polymerized porous matrix composed of adsorbents and organogelators can provide a new strategy for solving this problem. The gelling mechanism of aluminum 12-hydroxystearate (Al HSA) to form spherical nano micelles in solvents was investigated via UV-vis, FT-IR, and XRD. A creative method for aluminum soap-lignin gelator (OTS-AL/Al HSA) syntheses was put forward through the saponification of 12-hydroxystearic acid (HSA) and lignin via epichlorohydrin (ECH) crosslinking. By adjusting the ECH content, the growth of Al HSA nanoparticles (15-40 nm) on lignin can be realized, and the accordingly increased roughness endowed gelator with better hydrophobicity (WCA of 134.6°) before octadecyltrichlorosilane (OTS) modification. Thanks to the porous structures, the gelator powder exhibited a high sorption capacity in the range of 3.5-5.2 g g-1 for oils and organic solvents. Rheological studies demonstrated high mechanical strength of gels (>1.6 × 105 pa) and the gelator still retained 70% sorption capacity after 6 gelation-distillation cycles. The gelation characteristics of OTS-AL/Al HSA were attributed to the rapid sorption of oils by lignin and the self-assembly of Al HSA nano micelles on lignin to form an aggregated network structure trapping oils, thus realizing the synergistic effect of oil sorption-gelation.

The structure, characterization and immunomodulatory potential of exopolysaccharide produced by Planococcus rifietoensis AP-5 from deep-sea sediments of the Northwest Pacific.

Polysaccharides derived from microorganisms exhibit diverse structures and bioactivities, making them promising candidates for the treatment of various diseases. However, marine-derived polysaccharides and their activities are relatively little known. In this work, fifteen marine strains were isolated from surface sediments in the Northwest Pacific Ocean for screening of EPS production. Planococcus rifietoensis AP-5 produced a maximum yield of EPS at 4.80 g/L. The purified EPS (referred to as PPS) had a molecular weight of 51,062 Da and contained amino, hydroxyl, and carbonyl groups as its major functional groups. PPS primarily consisted of →3)-α-D-Galp-(1 â†’ 4)-α-D-Manp-(1 â†’ 2)-α-D-Manp-(1 â†’ 4)-α-D-Manp-(1 â†’ 4,6)-α-D-Glcp-(1 â†’ 6)-ß-D-Galp-(1→, with a branch consisting of T-ß-D-Glcp-(1→. Additionally, surface morphology of PPS was hollow, porous, and sphere-like stack. PPS primarily contained C, N, and O elements, with a surface area of 33.76 m2/g, a pore volume of 0.13 cc/g, and a pore diameter of 1.69 nm, respectively. Based on the TG curve, the degradation temperature of PPS was measured to be 247 °C. Furthermore, PPS demonstrated immunomodulatory activity through dose-dependently upregulating the expression level of cytokines. It significantly enhanced the cytokine secretion at a concentration of 5 µg/mL. To sum up, this study offers valuable insights for screening marine polysaccharide-based immunomodulators.

A step closer to real practice: Integrated tandem photocatalysis-biofilm process towards degradation of crude oil.

Intimately coupled photocatalysis and biodegradation (ICPB) systems represent a promising wastewater treatment technology. The implementation of ICPB systems for oil spill treatment is a pressing concern. In this study, we developed an ICPB system comprising BiOBr/modified g-C3N4 (M-CN) and biofilms for the treatment of oil spills. The results demonstrate that the ICPB system achieved the rapid degradation of crude oil, outperforming the single photocatalysis and biodegradation methods by degrading 89.08 ± 5.36% within 48 h. The combination of BiOBr and M-CN formed a Z-scheme heterojunction structure, enhancing the redox capacity. The interaction between the holes (h+) and the negative charge on the biofilm surface promoted the separation of electrons (e-) and h+, thereby accelerating the degradation process of crude oil. Moreover, ICPB system maintained an excellent degradation ratio after three cycles and its biofilms progressively adapted to the adverse effects of crude oil and light. The microbial community structure remained stable throughout the degradation of crude oil, with Acinetobacter and Sphingobium identified as the dominant genera in biofilms. The proliferation of the Acinetobacter genus appeared to be the main factor contributing to the promotion of crude oil degradation. Our work demonstrates that the integrated tandem strategies perhaps represent a feasible pathway toward practical crude oil degradation.

Assessment of eutrophication from Xiaoqing River estuary to Laizhou Bay: Further warning of ecosystem degradation in typically polluted estuary.

The coast of Laizhou Bay is plagued by a number of environmental issues, such as eutrophication, which are likely to worsen over the next few decades as a result of trends toward industrialization and urbanization. High nutrient levels in the Xiaoqing River are believed to be the main cause of Laizhou Bay becoming eutrophicated. Therefore, we conducted two cruises from the Xiaoqing River estuary to Laizhou Bay in August 2022 and December 2022, respectively, in the wet and dry periods to assess the potential impact of status of eutrophication due to human activities. The results showed that the concentration of DIN was higher than the quality standard for water (fi > 1) in both the wet season (August 2022) and the dry season (December 2022). DIN has major environmental impacts in Laizhou Bay. The eutrophication level index and organic pollution index have obvious spatial and temporal characteristics. In terms of time, the dry season is higher than the wet season. In space, Xiaoqing estuary is higher than Laizhou Bay. In the two surveys, DIN and DIP concentrations were significantly positively correlated, indicating that N and P pollution in the region had a common source and destination, and the spatial distribution was also similar. In addition, the current environmental conditions in the region are not ideal, reaching moderate and severe eutrophication levels, which proves that the ecosystem has the risk of aggravating degradation. As the Xiaoqing River is about to resume full navigation, human-related nutrient input (especially DIN) will continue to increase, and it is expected that the eutrophication risk in this area will increase in the next few years due to the increase in nutrient load.

The Role of Bacteria in the Formation and Migration of Oil-Particle Aggregates (OPAs) after Marine Oil Spills and the Associated Mechanism.

Oil spills interact with mineral particles to form oil-particle aggregates (OPAs), which promotes the oil's natural diffusion and biodegradation. We investigated the effect of bacteria on the formation and vertical migration of OPAs under different concentrations and types of particles and proposed and elucidated an oil-particle-bacteria coupling mechanism. The depth of particle penetration into oil droplets (13-17 µm) was more than twice that of the nonbacterial group. Oil that remained in the water column and deposited to the bottom decreased from 87% to 49% and increased from 14% to 15% at high/low concentration, respectively. Interestingly, the median droplet diameter showed a negative correlation (R2 = 0.83) and positive correlation (R2 = 0.60) at high/low concentration, respectively, with the relative penetration depth first proposed. We further demonstrated that bacteria increased the penetrating depth by a combination of reducing/increasing the interfacial tension, reducing the oil amount (C17-C38) in the OPAs, and increasing the particle width. These effects reduced the droplet size and ultimately changed the vertical migration of OPAs. Finally, we provided a simple assessment of the vertical distribution of OPAs in nearshore environments based on experimental data and suggested that the role of bacteria in increasing the depth of particles penetrating into the oil droplets should not be ignored. These findings will broaden the research perspective of marine oil spill migration.

Quantitative analysis of biosurfactants in water samples by a modified oil spreading technique.

The oil spreading technique relies on biosurfactant to reduce the surface tension of an oil film and form an oil spreading ring in the center, and then judges the content of biosurfactant according to the diameter of the spreading ring. However, the instability and large errors of the traditional oil spreading technique limit its further application. In this paper, we modified the traditional oil spreading technique by optimizing the oily material, image acquisition and calculation method, which improves the accuracy and stability of the quantification of biosurfactant. We screened lipopeptides and glycolipid biosurfactants for rapid and quantitative analysis of biosurfactant concentrations. By selecting areas by color done by the software to modify image acquisition, the results showed that the modified oil spreading technique has a good quantitative effect, reflected in the concentration of biosurfactant being proportional to the diameter of the sample droplet. More importantly, using the pixel ratio method instead of the diameter measurement method to optimize the calculation method, the region selection was more exact, and the accuracy of the data results was high, and the calculation efficiency was improved significantly. Finally, the contents of rhamnolipid and lipopeptide in oilfield water samples were judged by the modified oil spreading technique, the relative errors were analyzed according to the different substances as the standard, and the quantitative measurement and analysis of oilfield water samples (the produced water of Zhan 3-X24 and the injected water of the estuary oil production plant) were realized. The study provides a new perspective on the accuracy and stability of the method in the quantification of biosurfactant, and provided some theoretical and data support for the study of the microbial oil displacement technology mechanism.

Uncovering the dynamic evolution of microbes and n-alkanes: Insights from the Kuroshio Extension in the Northwest Pacific Ocean.

Biomarkers offer unique insights into the state of the environment, but little is known about how they interact with microbial communities in the open ocean. This study investigated the correlative effects between microbial communities and n-alkane distribution in surface seawater and sediments from the Kuroshio Extension in the Northwest Pacific Ocean. The n-alkanes in both surface seawater and surface sediments were mostly derived from algae and higher plants, with some minor contributions from anthropogenic and biological sources. The composition of microbial communities in surface seawater and sediments was different. In surface seawater, the dominant taxa were Vibrio, Alteromonas, Clade_Ia, Pseudoalteromonas, and Synechococcus_CC9902, while the taxa in the sediments were mostly unclassified. These variations/fluctuations of n-alkanes in three areas caused the aggregation of specialized microbial communities (Alteromonas). As the characteristic composition indexes of two typical n-alkanes, Short-chain n-alkane carbon preference index (CPI-L) and long-chain n-alkane carbon preference index (CPI-H) significantly influenced the microbial community structure in surface seawater, but not in surface sediments. Effect of CPI on microbial communities may be attributed to anthropogenic inputs or petroleum pollution. The abundance of hydrocarbon degradation genes also varied across the three different areas. Our work underscores that n-alkanes in the oceans alter the microbial community structure and enrich associated degradation genes. The functional differences in microbial communities within different areas contribute to their ecological uniqueness.

Multi-energies assisted and all-weather recovery of crude oil by superhydrophobic melamine sponge.

Efficient and safe recovery of high-viscosity marine crude oil spills is still a worldwide challenge. High-viscosity crude oil is difficult to be removed by traditional adsorbent materials. Although some recent developments in photothermal or electric-thermal oil-absorbing materials, the vertical heat transfer inside and the potential hazard of electrical leakage are difficult to be guaranteed. In order to overcome these problems, we polymerized dopamine (DA) in situ on the skeleton surface of the commercial melamine sponge (MS), and further coated the full-wavelength light-absorbing Fe3O4 NPs-Graphene (HF-G) on it to obtain the superhydrophobic sponge with excellent photothermal conversion effect, heat conductivity and magnetic heating capabilities (HF-G/PDA@MS). When the thickness of sponge is 5 mm, the HF-G/PDA@MS shows excellent vertical heat conductivity ability, and can absorb about 80 g/g. It also can be combined with an extra electric-heating device to achieve continuous heating to reduce the viscosity and recover crude oil at night or extreme weather. In addition, the temperature of HF-G/PDA@MS can reach about 40 °C by electromagnetic induction heater, indicating that we can use multiple energies-assisted modes to heat the HF-G/PDA@MS to. This work provides a promising solution and theoretical support for all-weather solving offshore crude oil spills pollution and recovery.

Preparation of MOF/polypyrrole and flower-like MnO2 electrodes by electrodeposition: High-performance materials for hybrid capacitive deionization defluorination.

Fluorine pollution has become a global public health problem due to its adverse health effects. Adsorption is the primary method for removing fluoride from drinking water. However, the adsorption method has disadvantages such as difficulty in recovering the adsorbent, and the need to add additional chemicals for regeneration, thereby causing secondary pollution, which limits further industrial applications. Capacitive deionization (CDI), as an emerging water treatment technology, has attracted widespread attention due to its advantages of simple operation, low energy consumption and less environmental impact. In this study, a polypyrrole (PPy) film was prepared on a graphite substrate by electrodeposition, and then metal-organic framework Ce/Zn-BDC-NH2 (CZBN) was deposited on the PPy film by electrophoretic deposition to obtain CZBN/PPy electrode was obtained. The CZBN/PPy anode was then coupled with the MnO2 cathode for capacitive removal of fluoride in a CDI cell. Both CZBN/PPy and MnO2 electrodes exhibit pseudocapacitive behavior, which can selectively and reversibly intercalate F- (CZBN/PPy) and Na+ (MnO2) ions. As expected, the CZBN/PPy-MnO2 system exhibits excellent fluorine removal performance. In 1.2 V, 100 mg/L F- solution, the F- removal capacity can reach 55.12 mg/g. It has high F- selectivity in the presence of some common anions, and can maintain high F- removal ability even after five adsorption regeneration processes. The mechanism of F- removal was studied by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). F- was mainly removed by electrostatic interaction and ion exchange with hydroxyl. The excellent defluorination performance of the CZBN/PPy-MnO2 system makes it have good practical application prospects.

Effect of fermentation pH on the structure, rheological properties, and antioxidant activities of exopolysaccharides produced by Alteromonas australica QD.

The pH value was essential for the growth and metabolism of microorganisms. Acidic pH exopolysaccharide (AC-EPS) and alkaline pH exopolysaccharide (AL-EPS) secreted by A. australica QD mediated by pH were studied in this paper. The total carbohydrate content and molecular weight of AC-EPS (79.59% ± 2.24% (w/w), 8.374 × 105 Da) and AL-EPS (82.48% ± 1.46% (w/w), 6.182 × 105 Da) were estimated and compared. In AC-EPS, mannose (3.78%) and galactose (3.24%) content was more, while the proportion of glucuronic acid was less in comparison to AL-EPS. The scanning electron microscopy revealed the structural differences among the AC-EPS and AL-EPS. Thermogravimetric analysis showed degradation temperatures of 272.8 °C and 244.9 °C for AC-EPS and AL-EPS, respectively. AC-EPS was found to exhibit better rheological properties and emulsifying capabilities, while AL-EPS had superior antioxidant activities. Overall, both AC-EPS and AL-EPS have the potential to be used as emulsifiers and biological antioxidants.

Characterization and protective effect against ultraviolet radiation of a novel exopolysaccharide from Bacillus marcorestinctum QDR3-1.

Although exopolysaccharide (EPS) has been applied to various fields, EPS for UVR-mediated oxidative stress repair still needs further exploration. In this study, a novel EPS was isolated from the fermentation medium of Bacillus sp. QDR3-1 and its yield was 4.8 g/L (pH 8.0, 12 % glucose, 30 °C and 6 % NaCl). The pure fraction (named EPS-M1) was purified by DEAE-cellulose and Sephadex G-100 column. EPS-M1 was a heteropolysaccharide composed of Man, Glc, Gal, and Fuc with a molecular weight of 33.8 kDa. Scanning electron microscopy (SEM) observed a rough surface and reticular structure of EPS-M1, and EPS-M1 formed spherical aggregates in aqueous solution observed in atomic force microscopy (AFM). Thermal analysis revealed that the degradation temperature of EPS-M1 was 306 °C. Moreover, methylation and NMR analysis determined that EPS-M1 was consisted of →3)-Manp-(1→, →2,6)-Manp-(1→, →4,6)-Glcp-(1→, →3)-Glcp-(1→, →4)-Galp-(1→, →4)-Fucp-(1→, and T-Manp-(1→. Furthermore, the cytotoxicity and the repair ability of UVR-mediated cell damage of EPS-M1 were studied with L929 cells. The results showed that EPS-M1 had good biocompatibility and it could mitigate UVR-mediated cell damage by regulating the levels of cellular reactive oxygen species (ROS), depolarization of mitochondrial membrane potential (MMP) and Caspase-3/7 activity. Overall, the structure analysis and the protective effects of EPS against L929 cells exposed to UVR provided an experimental basis for EPS in practical applications.

Effect of terminal electron acceptors on the anaerobic biodegradation of PAHs in marine sediments.

The existing polycyclic aromatic hydrocarbons (PAHs) in marine sediment has become a critical threat to biological security. Terminal electron acceptor (TEA) amendment has been applied as a potential strategy to accelerate bioremediation in sediment. HCO3-, NO3-, and SO42- were separately added to anaerobic sediment system containing five kinds of PAH, namely, phenanthrene, anthracene, fluoranthene, pyrene and benzo(a)pyrene. PAH concentration, PAH metabolites, TEA concentration, and electron transport system (ETS) activity were investigated. The HCO3- amendment group achieved the max PAH degradation efficiency of 84.98 %. SO42- group led to the highest benzo(a)pyrene removal rate of 69.26 %. NO3- had the lowest PAH degradation rate of 76.16 %. ETS activity test showed that NO3- significantly inhibited electron transport activity in the sediment. The identified PAH metabolites were the same in each group, including 4,5-dimethylphenanthrene, 3-acetylphenanthrene, 9,10-anthracenedione, pyrene-7-hydroxy-8-carboxylic acid, anthrone, and dibenzothiophene. After 126 d's anaerobic degradation at 25 °C, the utilization of HCO3- and SO42- as selected TEAs promoted the PAH biodegradation performance better than the utilization of NO3-.

Mesoscale evaluation of oil submerging and floating processes during marine oil spill response: Effects of dispersant on submerging stability and the associated mechanism.

The migration of oil spills in marine environment is still not clear, especially the key processes of submerging and floating, which is an important concern for effective disposal of oil spills. In mesoscale wave tank (32 m × 0.8 m × 2 m), this study has evaluated the characteristics of oil submergence based on oil concentration and oil droplet size. The concept of effective submergence is put forward for the first time, utilized to analyze the effects of dispersant on submerging stability and associated mechanisms. The results indicate dispersants increase submerged oil concentration and promote homogeneous distribution and vertical penetration. Of concern is that dispersants increase the proportion of small oil droplets (2.5-70 µm), prolonging the residence time of oil droplets in water by delaying the floating process. Dispersants sharply reduce oil droplets size (VMD<44 µm) thus decreasing the coalescence probability. These contribute to better submerging stability. By contrast, the submerged oil, formed as oil patches, oil streamers, and large oil droplets (VMD>170 µm) when without dispersant, will float and reattach to oil slicks more quickly due to their large volume. These findings help to clarify spilled oil behaviors and provide a new idea for the research on oil submergence.

A solar-heated antibacterial sodium alginate aerogel for highly efficient cleanup of viscous oil spills.

HYPOTHESIS: Major oil spills highlight the need for environmentally responsible and cost-effective recovery technologies. However, challenges remain for heavy oil spill recovery because of its high viscosity and low fluidity. To achieve this goal, an ecofriendly bio-based aerogel with efficient photothermal conversion ability was developed as a novel absorbent to achieve the fast removal of heavy oil spill by reducing the oil viscosity. EXPERIMENTS: From the renewable and abundant raw material sodium alginate (SA), hydrophobic and antibacterial SA/graphene oxide/ZIF-8 aerogel (SAGZM) was successfully fabricated via freezing-drying and chemical vapor deposition (CVD) technique. A series of characterization and tests, including aerogel structure, selective wettability, photothermal conversion ability, crude oil removal capability, and antibacterial ability, have been investigated in detail. SAGZM aerogels have rich pore structure, high porosity, excellent mechanical properties, and better photothermal conversion efficiency. FINDINGS: Under sunlight illumination, the recovery ability of SAGZM for heavy crude oil was investigated through infrared thermal imaging, oil permeability behavior analysis, and the continuous absorption for crude oil. In addition, these results are well supported by the theoretical liquid absorption coefficient. This study indicates that SAGZM is highly efficient in in situ regulating oil viscosity through its remarkably photothermal conversion capability. Importantly, SAGZM possesses an excellent antibacterial ability that is often neglected in the design of environmentally friendly materials in extending its service life. The findings of this work not only provide an eco-friendly bio-based aerogel material but also demonstrate that the photo-responsive SAGZM is efficient in heavy crude oil absorption. The proposed solar-heated SA-based aerogel provides a sustainable approach and material to solve the recovery problem of viscous crude oil spills.