Oil-contaminated Seawater Research Articles

Bifunctional Janus Membranes for Multicomponent Contaminated Seawater Separation and Recovery.

Solar-driven interface desalination has emerged as a promising strategy to address the global freshwater shortage crisis. However, the separation and recovery of multicomponent oil-contaminated seawater remain a key challenge. This study reports a novel high-strength Janus photothermal membrane with a unique reverse wettability design. On one side, the membrane has hydrophilic and oleophobic properties, while on the other, it has hydrophobic and oleophilic characteristics. The Janus membrane demonstrates dual functionality: solar desalination and oil-water separation. This dual functionality enables efficient separation and recovery of four components from contaminated seawater: purified water, salt crystals, light oil, and heavy oil. As a result, the Janus membrane achieves an evaporation rate of 2.06 kg m-2 h-1 under 1.0 sun. The ion (Na+, K+, Ca2+, and Mg2+) removal rate approaches 100% with nearly complete recovery of salt crystals. Furthermore, various types of oils can be accurately separated, with separation efficiency approaching 100%. An integrated separation device successfully separates and recovers the four components. This research presents significant potential for efficient separation and recovery of complex components in oil-contaminated seawater.

Driving mechanisms for the adaptation and degradation of petroleum hydrocarbons by native microbiota from seas prone to oil spills

Offshore waters have a high incidence of oil pollution, which poses an elevated risk of ecological damage. The microbial community composition and metabolic mechanisms influenced by petroleum hydrocarbons vary across different marine regions. However, research on metabolic strategies for in-situ petroleum degradation and pollution adaptation remains in its nascent stages. This study combines metagenomic techniques with gas chromatography-mass spectrometry (GC-MS) analysis. The data show that the genera Pseudoalteromonas, Hellea, Lentisphaera, and Polaribacter exhibit significant oil-degradation capacity, and that the exertion of their degradation capacity is correlated with nutrient and oil pollution stimuli. Furthermore, tmoA, badA, phdF, nahAc, and fadA were found to be the key genes involved in the degradation of benzene, polycyclic aromatic hydrocarbons, and their intermediates. Key genes (INSR, SLC2A1, and ORC1) regulate microbial adaptation to oil-contaminated seawater, activating oil degradation processes. This process enhances the biological activity of microbial communities and accounts for the geographical variation in their compositional structure. Our results enrich the gene pool for oil pollution adaptation and degradation and provide an application basis for optimizing bioremediation intervention strategies.

Isolation and characterization of a newly chrysene-degrading Achromobacter aegrifaciens.

Polycyclic aromatic hydrocarbons (PAHs) are considered substances of potential human health hazards because of their resistance to biodegradation and carcinogenic index. Chrysene is a PAH with a high molecular weight (HMW) that poses challenges for its elimination from the environment. However, bacterial degradation is an effective, environmentally friendly, and cost-effective solution. In our study, we isolated a potential chrysene-degrading bacteria from crude oil-contaminated seawater (Bizerte, Tunisia). Based on 16SrRNA analysis, the isolate S5 was identified as Achromobacter aegrifaciens. Furthermore, the results revealed that A. aegrifaciens S5 produced a biofilm on polystyrene at 20 °C and 30 °C, as well as at the air-liquid (A-L) interface. Moreover, this isolate was able to swim and produce biosurfactants with an emulsification activity (E24%) over 53%. Chrysene biodegradation by isolate S5 was clearly assessed by an increase in the total viable count. Confirmation was obtained via gas chromatography-mass spectrometry (GC-MS) analyses. A. aegrifaciens S5 could use chrysene as its sole carbon and energy source, exhibiting an 86% degradation of chrysene on day 7. In addition, the bacterial counts reached their highest level, over 25 × 1020 CFU/mL, under the conditions of pH 7.0, a temperature of 30 °C, and a rotary speed of 120 rpm. Based on our findings, A. aegrifaciens S5 can be a potential candidate for bioremediation in HMW-PAH-contaminated environments.

Simultaneous immobilization enhances synergistic interactions and crude oil removal of bacterial consortium

Oil spillage has serious adverse effects on marine environments. The degradation of crude oil by microorganisms may be an effective and sustainable approach. In this study, the removal of crude oil from seawater by immobilized bacterial consortium was performed and the enhancement of crude oil degradation efficiency by varying immobilization methods and inoculum volume ratio was examined. The nonpathogenic and heavy metal-tolerant bacterial consortium of Sphingobium naphthae MO2-4 and Priestia aryabhattai TL01-2 was immobilized by biofilm formation on aquaporousgels. The simultaneous immobilization of strains MO2-4 and TL01-2 showed better crude oil removal efficiency than independent immobilization, which indicated positive interactions among consortium members in the mixed-culture immobilized systems. Moreover, the immobilized consortium at a 2:1 (MO2-4:TL01-2) inoculum volume ratio showed the best crude oil removal capacity. The immobilized consortium removed 77% of 2000 mg L−1 crude oil in seawater over 7 days. The immobilized consortium maintained crude oil removal efficacy in semicontinuous experiments. In addition, the immobilized consortium was used to remediate seawater contaminated with 1000 mg L−1 crude oil in a 20 L wave tank. After 28 days, the crude oil degradation efficiency of immobilized consortium was approximately 70%, and crude oil degradation through natural attenuation was not observed. Moreover, the genomic features of strains MO2-4 and TL01-2 are reported. Genomic analyses of both strains confirmed the presence of many genes involved in hydrocarbon degradation, heavy metal resistance, biosurfactant synthesis, and biofilm formation, supporting the biodegradation results and characterizing strain properties. The results of this work introduce the potential benefit of simultaneous immobilization of bacterial consortia to improve efficiency of crude oil biodegradation and has motivated further investigations into large-scale remediation of crude oil-contaminated seawater.

Oil-contaminated sites act as high-risk pathogen reservoirs previously overlooked in coastal zones

In addition to the organic pollutants and disturbance to the microbial, plant and animal systems, oil contamination can also enrich opportunistic pathogens. But little is known about whether and how the most common coastal oil-contaminated water bodies act as reservoirs for pathogens. Here, we delved into the characteristics of pathogenic bacteria in coastal zones by constructing seawater-based microcosms with diesel oil as a pollutant. 16S rRNA gene full-length sequencing and genomic exploration revealed that pathogenic bacteria with genes involved in alkane or aromatic degradation were significantly enriched under oil contamination, providing a genetic basis for them to thrive in oil-contaminated seawater. Moreover, high-throughput qPCR assays showed an increased abundance of the virulence gene and enrichment in antibiotics resistance genes (ARGs), especially those related to multidrug resistance efflux pumps, and their high relevance to Pseudomonas, enabling this genus to achieve high levels of pathogenicity and environmental adaptation. More importantly, infection experiments with a culturable P. aeruginosa strain isolated from an oil-contaminated microcosm provided clear evidence that the environmental strain was pathogenic to grass carp (Ctenopharyngodon idellus), and the highest lethality rate was found in the oil pollutant treatment, demonstrating the synergistic effect of toxic oil pollutants and pathogens on infected fish. A global genomic investigation then revealed that diverse environmental pathogenic bacteria with oil degradation potential are widely distributed in marine environments, especially in coastal zones, suggesting extensive pathogenic reservoir risks in oil-contaminated sites. Overall, the study uncovered a hidden microbial risk, showing that oil-contaminated seawater could be a high-risk pathogen reservoir, and provides new insights and potential targets for environmental risk assessment and control.

Fibrous MXene Aerogels with Tunable Pore Structures for High-Efficiency Desalination of Contaminated Seawater

HighlightsThe super-elastic and robust MXene aerogels are created herein by assembling the 1D fibrous MXenes with sufficiently large aspect ratios and superior flexibility.The underlying regulatory mechanism and a complete diagram for the pore structure evolution of MXene aerogels are revealed for the first time, which are particularly instructive for future structure-specific designs.Fibrous MXene aerogels exhibit 8.3% plastic deformation at the 1000th compressions and achieve high evaporation rate (1.48 kg m−2 h−1) and light to thermal conversion efficiency (92.08%) on oil-contaminated seawater.

Expired yogurt-derived, three-dimensional water evaporator with sustainable self-cleaning and high mechanical properties for the desalination and purification of oil-contaminated seawater

In this study, expired yogurt-derived three-dimensional water evaporators were developed using a freeze-drying calcination technique and applied to the desalination and purification of oil-contaminated seawater. By mixing polyvinyl alcohol and a super absorbent polymer, the maximum pressure of the expired yogurt-derived water evaporator is capable of being maintained at 2.5 MPa, which is much greater than any previously reported values. Moreover, super absorbent polymer and polyvinyl alcohol can also adjust the pyrrolic nitrogen content, thereby increasing light-to-heat efficiency by reducing the evaporation enthalpy of water. The optimized water evaporator exhibited an excellent solar evaporation rate of 3.25 kg m−2 h−1 and a high light-to-heat efficiency value of 96.47 % under one-sun irradiation. After desalination, the concentrations of Na+, K+, Mg2+, and Ca2+ ions satisfied drinking water standards. The optimized water evaporator exhibited excellent salt inhibition and antibacterial properties during the water evaporation process, resulting in a sustainable self-cleaning capability. The optimized water evaporator can purify oil-contaminated seawater because of its unique wetting characteristics and microporous structure. The expired yogurt-derived, three-dimensional water evaporator developed in this study shows great potential for the purification of oil-contaminated seawater.

Simultaneous solar-driven seawater desalination and continuous oil recovery

Oil spills and freshwater scarcity remain two worldwide challenging issues. Emerging efforts have been made either to recover oil from oil/water mixture or to extract freshwater from abundant seawater. However, almost all current devices focus on oil recovery or seawater desalination separately, which is lack of energy efficiency. Herein, we propose a design of mechanically robust, bi-functional graphene devices (BGDs), containing vertical graphene sheets decorated on inverted U-shaped graphene monoliths, to achieve simultaneous solar-driven vapor generation and continuous oil recovery from oil-contaminated seawater. Benefiting from the unique wettability design of the BGDs, water evaporates on the hydrophilic surfaces, and meanwhile oil can be spontaneously recovered through the hydrophobic/oleophilic interior channels due to siphon action. Moreover, the strong photothermal effect of vertical graphene can boost both the seawater desalination and oil recovery performance. As a result, a vapor generation rate of 2.04 kg m−2 h−1 and an oil recovery rate of 105.8 L m−2 h−1 are concurrently achieved under 1-sun irradiation. The design of bi-functional devices provides a new means to maximize the utilization of solar power and reduce the costs for multi-functional practical environmental engineering applications.

Magnetically recyclable 3D water evaporator for desalination and purification of oil-contaminated seawater

Desalination using solar-driven water evaporation is one of the most efficient, green, and sustainable approaches. However, the purification of oil-contaminated seawater, salt inhibition, and recovery of water evaporators remain challenging. Herein, a water evaporator based on a C/ZnFe2O4-x composite deposited on floral foam (FF) was developed, and its water evaporation performance was optimized by adjusting the reaction and calcination temperatures, concentration of deposited C/ZnFe2O4-x, and height of the FF. Owing to the excellent optical properties of C/ZnFe2O4-x, the water evaporator absorbed more than 96 % of sunlight in the wavelength range of 280–2500 nm, and its excellent magnetic properties promoted the recycling of the evaporator using a magnetic drive. The evaporator exhibited an excellent solar evaporation rate of 4.06 kg m−2 h−1, and a high light-to-heat conversion efficiency of 95.4 % under one-sun irradiation. The water evaporator exhibited excellent salt inhibition properties, and no salt crystals formed during the water evaporation process. The total organic carbon and organic dissolved matter in the purified water were significantly lower than those of the oil-contaminated seawater. Because of its low cost, high evaporation rate, and excellent durability, recyclability, and salt inhibition properties, the 3D evaporator can be a reliable device for purifying oil-contaminated seawater.

Oil-degrading bacterial consortium from Gulf of Mexico designed by a factorial method, reveals stable population dynamics

We describe an assembled marine bacterial consortium designed for bioremediation of oil-contaminated seawater, based on a statistical method using a Plackett-Burman (PB) experimental approach. The final consortium consists of four bacteria isolated from the Gulf of Mexico, from four genera: Pseudomonas, Halopseudomonas, Paenarthrobacter, and Alcanivorax. Individually, bacterial oil removal by these microorganisms was evaluated by gravimetry, reaching 39% at maximum after 75 days, whereas in consortium it was ~62%. We also measured biodegradation levels by Gas Chromatography/Mass Spectrometry (GC-MS) observing 12 polyaromatic hydrocarbons (PAHs) degradation analyzed and n-alkanes degradation with a preference for specific chain length. Consortium population analysis using the V3-V4 region of 16S rRNA showed a stable community, suggesting that the metabolic load was distributed among bacteria and that stable dynamic interactions were achieved. In this work, we show that the use of a factorial method for synthetic consortium design offers the possibility of improving oil degradation efficiency with stable bacterial populations.

Hydrolysis of Methylumbeliferyl Substrate Proxies for Esterase Activities as Indicator for Microbial Oil Degradation in the Ocean: Evidence from Observations in the Aftermath of the Deepwater Horizon Oil Spill (Gulf of Mexico)

Biological oil weathering facilitated by specialized heterotrophic microbial communities plays a key role in the fate of petroleum hydrocarbon in the ocean. The most common methods of assessing oil biodegradation involve (i) measuring changes in the composition and concentration of oil over time and/or (ii) biological incubations with stable or radio-labelled substrates. Both methods provide robust and invaluable information on hydrocarbon biodegradation pathways; however, they also require extensive sample processing and are expensive in nature. More convenient ways to assess activities within microbial oil degradation networks involve measuring extracellular enzyme activity. This perspective article synthesizes previously published results from studies conducted in the aftermath of the 2010 Deepwater Horizon (DwH) oil spill in the northern Gulf of Mexico (nGoM), to test the hypothesis that fluorescence assays of esterases, including lipase activity, are sensitive indicators for microbial oil degradation in the ocean. In agreement with the rates and patterns of enzyme activity in oil-contaminated seawater and sediments in the nGoM, we found close correlations between esterase activity measured by means of methylumbeliferyl (MUF) oleate and MUF butyrate hydrolysis, and the concentration of petroleum hydrocarbons in two separate laboratory incubations using surface (<1 m) and deep nGoM waters (>1200 m). Correlations between esterase activities and oil were driven by the presence of chemical dispersants, suggesting a connection to the degree of oil dissolution in the medium. Our results clearly show that esterase activities measured with fluorogenic substrate proxies are a good indicator for oil biodegradation in the ocean; however, there are certain factors as discussed in this study that need to be taken into consideration while utilizing this approach.

Flexible CuO-rGO/ PANI thermal absorber with high broadband photoresponse and salt resistance for efficient desalination of oil-contaminated seawater

Solar Steam Generation (SSG) is a promising and efficient technology to limit the global water scarcity issue. Nevertheless, it is challenging to utilize versatile photothermal absorbers with salt-resistance and anti-oil-fouling capability through a facile, scalable, and cost-effective fabrication technique. This work demonstrated the combination of cheap semiconductor material with a porous ionic polymer (PIP), emeraldine salt (ES) form of polyaniline (PANI), as salt-resistant and oil-repellent evaporator, which was synthesized through a facile and cost-effective one-step method. PANI enhanced the photoresponse of the CuO-rGO and its honeycomb-like structure increased the photothermal conversion due to the multi-scattering of the incident light. The CuO-rGO/PANI achieved an evaporation rate of 2.02 kg m−2 h−1 and a solar-to-steam efficiency of 94.2% under 1 sun illumination. Furthermore, the composite presented high in-water (138.5°) and in-air (135.2°) oil contact angles with simultaneously high-water affinity (<8°) which proved the hydrophilicity and oleophobicity of this membrane. CuO-rGO/PANI can work effectively in high-concentration brine with no activity loss, due to the “Donnan exclusion” effect generated from cationic quinonoid and benzenoid structure of ES-PANI against cations from saline solution, which exhibit superb durable evaporation performance over 10 cycles.

Biodegradation Potential of Bacillus sp. PAH-2 on PAHs for Oil-Contaminated Seawater.

Microbial degradation is a useful tool for inhibiting or preventing polycyclic aromatic hydrocarbons (PAHs) widely distributed in marine environment after oil spill accidents. This study aimed to evaluate the potential and diversity of bacteria Bacillus sp. PAH-2 on Benzo (a) anthracene (BaA), Pyrene (Pyr), and Benzo (a) pyrene (BaP), their composite system, aromatic components system, and crude oil. The seven-day degradation rates against BaA, Pyr, and BaP were 20.6%, 12.83%, and 17.49%, respectively. Further degradation study of aromatic components demonstrated PAH-2 had a high degradation rate of substances with poor stability of molecular structure. In addition, the degradation of PAHs in crude oil suggested PAH-2 not only made good use of PAHs in such a more complex structure of pollutants but the saturated hydrocarbons in the crude oil also showed a good application potential.

ВПЛИВ ФІЗИЧНИХ І ОКЕАНОГРАФІЧНИХ ФАКТОРІВ НА РОЗШИРЕННЯ ЗОНИ ЗАБРУДНЕННЯ КАСПІЙСЬКОГО МОРЯ (ПІВНІЧНО-СХІДНА ПРИБЕРЕЖНА ЗОНА АЗЕРБАЙДЖАНУ)

Aim. Our main goal is to study the spread of pollution caused by natural and anthropogenic factors in the water area of the Caspian Sea, the largest closed basin in the world, according to physical and oceanographic factors. The methodological basis of the article. The article uses methods of processing statistical indicators and selects the Brooks-Koch method to calculate the rise height (∆H0) of wastewater in a stratified environment. Results. In the water area of the Republic of Azerbaijan, the pollution of the Caspian Sea occurs mostly in the Absheron Peninsula. The main reason for this is that the area is rich in oil and gas reserves and there are many oil production enterprises. In addition to natural factors such as wind, temperature and currents, anthropogenic factors also influence the spread of oil-contaminated seawater. As a result of the analysis of the physical and oceanographic factors, we determined that the depth of sewage should be more than 70 meters when it is discharged into the sea. The main reason for this is that the sewage dumped in the depth is mixed with the cold, and with time, heavy bottom currents. As sewage mixed with clean seawater rises to the surface, it continues to mix in the intermediate layers because its weight is heavier than the layer above it. The main reason why this happens only in the Caspian Sea is that the temperature of the sea water increases instead of decreasing with depth. The fact that the turbulent mixing coefficient calculated for the area confirmed in the article is 104-106 shows that the concentration pulsation intensifies with the increase in the diameter of the sewage sludge. This situation creates conditions for the mixing of waste water with the surrounding water. Scientific novelty. The effect of physical and oceanographic factors on the change, expansion and deepening of the area of sewage in the Caspian Sea water area was studied. Also, the turbulent diffusion coefficient of pollution in coastal zones was calculated.

Enhanced bioremediation of diesel oil-contaminated seawater by a biochar-immobilized biosurfactant-producing bacteria Vibrio sp. LQ2 isolated from cold seep sediment

This study investigated the effect of immobilized biosurfactant-producing bacteria on the bioremediation of diesel oil-contaminated seawater. Initially, a biosurfactant-producing bacterium, LQ2, was isolated from a marine cold-seep region, and identified as Vibrio sp. The biosurfactant produced by LQ2 was characterized as a phospholipid, exhibiting high surface activity with strong stability. Meanwhile, the inoculation of biochar-immobilized LQ2 demonstrated superior efficiency in removing diesel oil (94.7%, reduction from 169.2 mg to 8.91 mg) over a seven-day period compared to free-cell culture (54.4%), through both biodegradation and adsorption. In addition, the microbial growth and activity were greatly enhanced with the addition of immobilized LQ2. Further experiment showed that degradation-related genes, alkB and CYP450–1, were 3.8 and 15.2 times higher in the immobilized LQ2 treatment, respectively, than those in the free cell treatment. The findings obtained in this study suggest the feasibility of applying immobilized biosurfactant-producing bacteria, namely LQ2, in treating diesel oil-contaminated seawater.

Advanced materials for immobilization of purple phototrophic bacteria in bioremediation of oil-polluted wastewater

Oil pollution which results from industrial activities, especially oil and gas industry, has become a serious issue. Cinder beats (CB), coconut fiber (CF) and polyurethane foam (PUF) are promising immobilization carriers for crude oil biodegradation because they are inexpensive, nontoxic, and non-polluting. The present investigation was aimed to evaluate this advanced technology and compare the efficiency of these immobilization carriers on supporting purple phototrophic bacterial (PPB) strains in hydrocarbon biodegradation of crude oil contaminated seawater. The surface of these biocarriers was supplemented with crude oil polluted seawater and immobilized by PPB strains, Rhodopseudomonas sp. DD4, DQ41 and FO2. Through scanning electron microscopy (SEM), the bacterial cells were shown to colonize and attach strongly to these biocarriers. The bacteria-driven carrier systems degraded over 84.2% supplemented single polycyclic aromatic hydrocarbons (PAHs). The aliphatic and aromatic components in crude oil that treated with carrier-immobilized consortia were degraded remarkably after 14 day-incubation. Among the three biocarriers, removal of the crude oil by CF-bacteria system was the highest (nearly 100%), followed by PUF-bacteria (89.5%) and CB-bacteria (86.3%) with the initial crude oil concentration was 20 g/L. Efficiency of crude oil removal by CB-bacteria and PUF-bacteria were 86.3 and 89.5%, respectively. Till now, the studies on crude oil degradation by mixture species biofilms formed by PPB on different carriers are limited. The present study showed that the biocarriers of an oil-degrading consortium could be made up of waste materials that are cheap and eco-friendly as well as augment the biodegradation of oil-contaminated seawater.

An innovative chemometric approach for simultaneous determination of polycyclic aromatic hydrocarbons in oil-contaminated waters based on dispersive micro-solid phase extraction followed by gas chromatography

In the present study, an analytical strategy was developed using reduced graphene oxide (rGO) as an effective sorbent in dispersive micro-solid phase extraction (DMSPE) for simultaneous determination of seven polycyclic aromatic hydrocarbons (PAHs) combined with gas chromatography (GC-FID). rGO was synthesized using modified Hummer’s method and characterized using scanning electron microscope(SEM), atomic force microscope (AFM) and Raman spectroscopy. A rotatable central composite design (CCD) combined with multiple linear regression (MLR) and analysis of variance (ANOVA) was used for designing, modelling and optimization of the extraction procedure. In this regard, principal component analysis (PCA) was used to develop a general response using the scores on the first PC instead of GC peak areas of seven PAHs to develop a global model. Finally, optimum DMSPE conditions were found as 0.7 mL sorbent volume, 0.05 mg mL−1 sorbent amount, 2.2 mL sample volume, 0.5 mL solvent extraction volume, 7.8 w w−1 salt concentration and 20 min vortex time. The optimized method was then used for identification and quantification of target PAHs in standard and real samples using partial least squares regression (PLSR). Multivariate analytical figures of merit (AFOMs) for PLS model including sensitivity (SEN), analytical sensitivity (γ), limit of detection (LOD) and limit of quantitation (LOQ) were calculated by focusing on estimation of signal and concentration which were in the range of (0.37–1.19), (0.87–2.49), (2.39–10.36 ng mL−1) and (7.17–21.36 ng mL−1), respectively. Thoroughly, multivariate analytical figures of merit were better than univariate ones. Finally, the proposed strategy was successfully tested for the analysis of real oil-contaminated sea water samples. The relative recovery (RR) and relative standard deviation (RSD) were in the range of (9.6–96.86) and (1.54–28.44), respectively.

Removal of high-molecular-weight polycyclic aromatic hydrocarbons by a microbial consortium immobilized in magnetic floating biochar gel beads

A bacterial consortium immobilized in magnetic floating biochar gel beads is proposed to remove high-molecular-weight polycyclic aromatic hydrocarbons. The microbial consortium performed better than single strains and consisted of four strains of marine bacteria for degrading pyrene (PYR), two strains for benzo(a)pyrene (BAP), and three strains for indeno(1,2,3-cd)pyrene (INP), which were isolated from oil-contaminated seawater. The immobilized cells could biodegrade 89.8%, 66.9% and 78.2% of PYR, BAP and INP, respectively, and had better tolerance to pH, temperature and salinity than free cells. The Andrews model was used to explore the biodegradation kinetics, and when the initial concentrations of PYR, BAP, and INP were 7.80, 3.05, and 3.41 mg/L, the specific biodegradation rates reached maximum values of 0.2507, 0.1286, and 0.1930 d−1, respectively. The immobilized microbial consortium had a high HMW-PAH removal ability and good floatability and magnetic properties and could be collected by an external magnetic field.

Plasma-Made Graphene Nanostructures with Molecularly Dispersed F and Na Sites for Solar Desalination of Oil-Contaminated Seawater with Complete In-Water and In-Air Oil Rejection.

Solar desalination that exploits interfacial evaporation represents a promising solution to global water scarcity. Real-world feedstocks (e.g., natural seawater and contaminated water) include oil contamination issues, raising a compelling need for desalination systems that offer anti-oil-fouling capability; however, it is still challenging to prepare oil-repellent and meanwhile water-attracting surfaces. This work demonstrates a concept of molecularly dispersing functional F and Na sites on plasma-made vertically oriented graphene nanosheets to achieve an in-air and in-water oleophobic, hydrophilic surface. The graphene architecture presents high in-air (138°) and in-water (145°) oil contact angles, with simultaneously high water affinity (0°). Such surface wettability is enabled by oleophobic, hydrophobic -CFx, and hydrophilic -COONa groups of the molecules that disperse on graphene surfaces; low-dispersion (0.439 mJ m-2) and high-polarity (95.199 mJ m-2) components of the solid surface tension; and increased surface roughness produced by graphene edges. The graphene nanostructures pump water upward by capillary action but repel oil from the surface, leading to complete in-water and in-air oil rejection and universal anti-oil-fouling capability for solar desalination. Consequently, stable solar-vapor energy efficiency of more than 85% is achieved regardless of whether the feedstock is pure or oil-contaminated water (e.g., a mixture of oil floating on water, an oil-in-water emulsion), resulting in the efficient production of clean water over several days. This outstanding performance is attributed to the universal (both in-water and in-air) oleophobic wettability, together with high light absorptance contributed by nanotraps, fast interfacial heat transfer enhanced by finlike nanostructures, and accelerated evaporation enabled by sharp graphene edges.

The effect of bioaugmentation with Exiguobacterium sp. AO-11 on crude oil removal and the bacterial community in sediment microcosms, and the development of a liquid ready-to-use inoculum

This study demonstrates the feasibility of using Exiguobacterium sp. AO-11 to remediate oil-contaminated environments. Bioaugmentation using AO-11 showed the best removal percentage, 75%, of 4% (w/w) crude oil in sediment microcosms in 100 days. In terms of the bacterial community structure during crude oil degradation, the addition of AO-11 did not change the indigenous bacterial community, while the addition of urea fertilizer induced structural shift of indigenous bacterial community. Exiguobacterium sp. AO-11 was developed as a bioremediation product, and a liquid formulation of AO-11 was developed. Coconut milk residue and soybean oil mill sludge were used for bacterial cultivation to reduce the production cost, and they could enhance bacterial cell growth. The liquid formulation of AO-11 prepared in phosphate buffer could be stored at 4 °C for at least 2 months, and it maintained efficacy in the treatment of crude oil-contaminated seawater. Overall, bioaugmentation with strain AO-11 could be an effective solution for the bioremediation of crude oil-contaminated environments.