Oil-polluted Water Research Articles

Fabrication of water-repellent double-layered polydopamine/copper films on mesh with improved abrasion and corrosion resistance by solution-phase reduction for oily wastewater treatment

Recently, superhydrophobic metal meshes for oily wastewater filtration have been widely reported. However, a facile and universal technique with easier operations to construct robustly superhydrophobic stainless steel (SS) mesh for dealing with oil-polluted water is still a challenge. Herein, a superhydrophobic SS mesh with stable polydopamine (PDA)-Cu nanoclusters (CNs) complexes was fabricated mainly on the basis of in situ growth approach. The as-prepared mesh is able to resist various organic solvents, corrosive solutions and strongly mechanical abrasion. It can be applied to purify water polluted by various types of oils with filtration efficiency as high as 96.6%. The separation efficiency (>97.2%) and water contact angle (>155.5°) remain very high even after 40 cycles of separation. Furthermore, the influence of the Cu2+ concentration on separation efficiency and oil permeation flux is also systematically investigated. This study gives a new technique to prepare durable and robustly superhydrophobic mesh for efficient and quick separation of the oils from water.

Wool-Like Fibrous Nonwoven Mesh with Ethanol-Triggered Transition between Antiwater and Antioil Superwetting States for Immiscible and Emulsified Light Oil-Water Separation.

Superwetting antiwater and antioil textiles are not only very attractive for efficient and cost-effective oil-water separation but also very challenging to be prepared. A well-designed polystyrene wool-like fibrous mesh was fabricated by a controlled electrospinning setup to provide simple and quick reversible ethanol-triggered switching between antiwater and antioil superwetting states in various media such as air, water, and oil. Additionally, it exhibits a long-term stability against acid, alkaline, and salt at high concentrations. Such characteristics will prove unusual capabilities for controllable gravity-driven separation of both immiscible and emulsified oil-water mixtures with a separation efficiency more than 99.0%, as well as a prolonged antifouling property and an excellent recyclability; all will be advantageous for technical applications including oil removing and water removing. Furthermore, light oil-polluted water and water-soluble pollutants can be simultaneously cleaned well by the antioil mesh acting in the water-removing mode.

Superhydrophobicity of polyvinylidene fluoride induced by integrating liquid-exfoliated hexagonal boron nitride nanosheets

The superhydrophobicity of polyvinylidene fluoride (PVDF) membranes can be achieved by adding a small amount of hexagonal boron nitride nanosheets ( h-BNNSs) during the preparation process. The h-BNNSs can be fabricated by two steps of facile ultrasonication of commercial h-BN powders in water and subsequent centrifugation process. The introduction of a small amount of h-BNNSs into PVDF will result in structure and morphology changes of final PVDF membranes. The changes of the structure and morphology can significantly reduce the surface wettability of PVDF membranes, even generating superhydrophobicity. However, the superoleophilicity of PVDF membranes is well kept, which is not influenced by the introduction of h-BNNSs. The excellent superhydrophobicity and superoleophilicity make these porous h-BNNS/PVDF composites to be promising candidates for separating oil and water as membranes in practical oil-polluted waste water treatment.

Poly(dimethylsiloxane)/graphene oxide composite sponge: a robust and reusable adsorbent for efficient oil/water separation.

The development of polymer sponges with large adsorption capacity, high oil/water selectivity and mechanical stability is an effective strategy for the separation of oil from oil-polluted water. The improvement in the adsorption performance for polymer sponges should not be accompanied by the sacrifice of mechanical properties and recycling stability, which are fundamental to their long-term operation in the cleanup of oil-spill accidents. In this work, we synthesized a robust and reusable sponge based on a poly(dimethylsiloxane) (PDMS) frame coated stereoscopically with graphene oxide (GO) via the amidation between PDMS and GO. The combination of the PDMS skeleton with the robust macroporous structure and GO nanosheets acting as mechanical fortifiers contributes to the nanocomposite sponge with great integrity and durability. The resultant PDMS/GO nanocomposite sponge exhibited a high compressive strength of 42.7 kPa with a strain of 60% after 50 cycles. The high adsorption capacity for various oils and organic solvents was obtained in the nanocomposite sponge, and the maximum capacity of 14.6 g g-1 was achieved for chloroform, which is ascribed to the large porosity and hydrophobicity caused by the rough PDMS skeleton covered by the GO nanosheets. Furthermore, a vacuum device with the nanocomposite sponge demonstrated effective separation for a large amount of oil/water mixture, with the maximum separation of 724 times the sponge weight during adsorption. This work provides a productive approach to develop porous polymer nanocomposites with high absorption properties and mechanical cycling stability and paves the path for the application of polymer sponges in oil pollution.

Effect of Nutrients on Bioremediation of Crude Oil-Polluted Water

Crude oil pollution has been a common challenge in the Niger Delta region of Nigeria. The use of biological remediation has helped to detoxify and restore the ecosystems damaged by crude oil spillage. Nutrient addition has been proven to be an effective strategy to enhance oil biodegradation, as they could utilize crude oil as the source of carbon and energy and give a reasonably high biodegradation rate. The effect of biostimulants on the bioremediation of crude oil-polluted water was investigated in this study. Four samples, each having crude oil to water ratio of 1:4 was used. Three sets of samples were each inoculated with microbial load 1x 106cfu/ml of Aspergillus Niger, and Pseudomonas Aeruginosa as microbial consortium. All the samples, including the controls, were closely observed for a period of seven weeks at one-week interval for the physiochemical parameters such as pH, Dissolved Oxygen (DO), Biochemical Oxygen Demand (BOD), Total Hydrocarbon Content (THC), turbidity, and total microbial count. Of all these parameters, only BOD, DO, turbidity, and THC were seen to decrease generally with time of remediation for all the samples. Maximum reductions in value of 94.04%, 97.45%, and 99.09% were achieved for turbidity, BOD, and THC respectively at the microbial consortium load of 1x 10 6cfu/ml.

Hydrophytes in the Oil-Polluted Water Bodies: Some Aspects of Functioning and Practical Use (a Review)

Hydrophytes in the Oil-Polluted Water Bodies: Some Aspects of Functioning and Practical Use (a Review)

Эпифитные бактерии бурых водорослей Fucus vesiculosus Linnaeus, 1753 (Баренцево море)

Бурые водоросли в симбиозе с эпифитными бактериями играют важную роль в биоремедиации морской среды после попадания в неё нефтепродуктов, поэтому их изучение в различных по уровню загрязнения местообитаниях представляется актуальным. Целью работы являлось определение методами сканирующей и трансмиссионной электронной микроскопии присутствия и локализации эпифитных бактерий бурых водорослей Fucus vesiculosus Linnaeus, 1753 из условно чистой (губа Зеленецкая, Восточный Мурман) и загрязнённой нефтепродуктами (Кольский залив, Мурманский морской порт) прибрежных акваторий Баренцева моря. Для учёта численности культивируемых гетеротрофных бактерий использован культуральный метод с применением жидких питательных сред. Выявлено, что бόльшая часть бактерий в эпифитном сообществе концентрируется в естественных углублениях поверхности таллома. В загрязнённой акватории бактерии локализуются также в слизистом слое на поверхности водорослей, на плёнке нефтепродуктов или под плёнкой, покрывающей талломы. Помимо гетеротрофных бактерий, в перифитоне растений обнаружены в большом количестве цианобактерии. Показано, что количество культивируемых эпифитных гетеротрофных бактерий на поверхности водорослей в загрязнённой акватории превышало 17 млн кл.·см-2, а в чистой акватории оно достигало 14,5 тыс. кл.·см-2. Количество культивируемых эпифитных углеводородокисляющих бактерий в водных массах загрязнённой нефтепродуктами акватории составляло до 17,4 тыс. кл.·см-2. В условно чистой акватории бактерии данной группы не обнаружены.

Bioremediation of Oil-Contaminated Brackish Salty Water and its Safe use in the Cultivation of Woody Trees and Economic Plants

Oil-mining companies have to subject waste water to expensive treatment before it can be discharged on land or at sea to comply with environment regulations. This study aims at developing an economically valid and applied comprehensive solution that takes advantage of oil-contaminated brackish salty water disposed by the General Petroleum Company in Egypt, and maximizes its economic value and ensures its safe use in the environment. Three fields in Ras Sudr site of the company were inspected. Two main common plant species to Ras Sudr, Tamarix niloteca tree and Phragmites australis grass that is tolerant to salinity. These plants together with their associated bacteria of endophytes and rhizosphere that utilize crude oil as a carbon and energy source was considered a useful combination of bioremediation agents. Initially, soil characteristics were determined by analyzing soil samples taken at depths of 25cm and 50cm, and bacterial content of soil around the roots and within plant tissues was examined. Discharged water (@50 m3 day-1) was used in irrigating plant fields in amounts sufficient to plant needs only. Growth parameters of plants were assessed four times in an interval of two months. Preliminary results indicated that growth rates in plant length, number of branches and stem girth, and chlorophyll content of oil-polluted water irrigated plants of the two plant species were not significantly different (p≤0.05) of plants irrigated with fresh water. The number of bacteria in the soil increase9d significantly (p≥0.05) over time, and the color of residual oil in the soil was fading, indicating the its decomposition. Soil under Tamarix niloteca contained similar quantities of microorganisms in both coastal saline-alkali soil and inland arid region indicating that colonization of the plant provided stable growth conditions for microorganisms. These plants and endophytes and rhizosphere combination played the main rule in the in-situ bioremediation process, and were efficient in removing around 70 % of the initial traces of crude oil within two months. They also provide safe environment and romote plant growth. They were able to decompose hydrocarbons and residues of crude oil as they possess special physiological mechanisms (PGPR) turns polluted water to safe water for human and environment, and meanwhile achieving the objectives of this work. These results indicated that Tamarix niloteca and Phragmites australis are promising agents for treating oil-polluted salty wastewater in other fields of crude oil mining.

A pair of MnO2 nanocrystal coatings with inverse wettability on metal meshes for efficient oil/water separation

Water contamination arising oil spill and industrial oily wastewater discharge has posed a severe threat to ecological environment and human health. To address the issues, the metal meshes with superwetting performance for selective oil/water separation have received extensive attention. But, it is still a great challenge to fabricate durable meshes with special wettability and high liquid intrusion pressure, which can be utilized for oil/water separation under harsh environments. Herein, two types of MnO2 nanocrystal coated meshes with inverse wettability, namely superhydrophobicity and underwater superoleophobicity, were fabricated via a single hydrothermal strategy or combining dipping modification. The resulting superhydrophobic mesh and underwater superoleophobic mesh are suitable for removing heavy oil and light oil from water, respectively. The oil/water separation efficiencies of greater than 96.2% are achieved for the two meshes. Importantly, both meshes exhibit quick separation rate for the permeable liquid and high intrusion pressure (>1.38 kPa) for the intercepted liquid, and can maintain excellent superwetting performance and high oil/water separation efficiency under harsh environments (acidic, alkakine and high-concentration salt solutions). We believe the as-fabricated meshes are promising and effective filters for purifying oil-polluted water.

Facile Two-Step Strategy for the Construction of a Mechanically Stable Three-Dimensional Superhydrophobic Structure for Continuous Oil-Water Separation.

It has been a big challenge to separate oil slicks from oil-polluted water sources efficiently and in an environmentally friendly way. Three-dimensional (3D) hydrophobic and superoleophilic materials have great potential in water separation continually. In this study, we developed a facile two-step strategy for fixing functionalized nanoparticles on 3D complex macroscopic surfaces. By using commercial glue to immobilize different types of nanoparticles on the surfaces of various 3D objects, superhydrophobic copper foam, cotton wool, and polyurethane (PU) sponge with strong stability and excellent performance were prepared. Owing to flexible fixing with the glue, the prepared PU sponge remained superhydrophobic after 950 mechanical compression cycles, 250 cycles of absorption/squeezing, or soaking in n-dodecane for 60 h. The prepared PU sponge was applied to the rapid absorption of clean oil on a water surface, and the feasibility of separating mixed oil through capillary separation of cavernous bodies was examined. Furthermore, the method for loading nanoparticles onto a 3D structure can be used with many self-cleaning, flexible electrodes and catalysts.

Recyclable biomass carbon@SiO2@MnO2 aerogel with hierarchical structures for fast and selective oil-water separation

Biomass carbon aerogels are emerging as attractive versatile materials have broad potential applications in various fields including energy storage, oil absorption and catalysts due to their abundance in nature, low cost and environmental friendliness. Here, we have successfully prepared a compressible, superhydrophobic and multifunctional hierarchical biomass carbon@SiO2@MnO2 aerogel (HBCSM aerogel) by using cost-effective and environmentally friendly sisal cellulose as main raw material. During this process, the cellulose@SiO2 aerogel (CS aerogel) was fabricated using sol-gel process, followed by carbonization to form biomass carbon@SiO2 aerogel (BCS aerogel). Then, the HBCSM aerogel was fabricated by in situ assembly of MnO2 nanosheets on the surface of the BCS aerogel under hydrothermal conditions. The incorporation of hierarchical SiO2@MnO2 structure into the HBCSM aerogel could not only improve the surface roughness and hydrophobic properties but also enhance the absorption capacity and mechanical durability. In addition, the HBCSM aerogel exhibits excellent superhydrophobicity with the water contact angle (WCA) of 155°. The as-prepared modified HBCSM aerogel exhibits a very large absorption capacity (60–120 g g−1) for different oils and organic solvents and the absorption capacity of the as-prepared aerogel shows a slight decrease after the repeated absorption and release of several oil and solvents for 9 cycles. This work provides a new procedure for fabrication of hybrid carbon aerogel with well-defined 3D hierarchical porous structures that may provide a new slight on the relationship between the structure and property of biomass carbon aerogel, making it a promising candidate for industrial oil-polluted water treatments and oil spill cleanup.

Superhydrophobic paper from conjugated poly(p-phenylene)s: Self-assembly and separation of oil/water mixture

The oil pollution is an increasing threat to nature and human health. Therefore, effective separation of oil from the oily wastewater is a challenging task. Through the nonsolvent vapor method, a superhydrophobic paper can be self-assembled by dropping the conjugated poly-p-phenylenes solution on the commercial filter paper in a nonsolvent vapor atmosphere. The numerous nano-mircostructral particles composed of polymer nanowires covered on the filter paper, just like the morphology of lotus leaves, lead to the excellent superhydrophobic effect. Moreover, the polymer-coated filter paper not only exhibits good mechanical stability, long-term durability, self-cleaning, but also has superhydrophobicity and superoleophilicity. The as-prepared paper possess remarkable oil/water separation ability for a variety of oil/water mixtures, including bromoethane, hexane, cyclohexane, petroleum ether, gasoline, dodecane, and the mixed oil of gasoline and diesel, demonstrating that it can be a good candidate for the treatment of industrial oil-polluted water.

Hydrobionts of a freshwater oil-polluted northern lake: bioaccumulation of heavy metals in fish and the rate of ecosystem recovery

The response of phytoplankton, zooplankton, benthic and fish community structure to one of the biggest oil spill in history of Komi Republic (north-west part of Russia) was investigated using data from a long-term survey off the polluted lake. The characteristics of aquatic freshwater communities observed in the study area 10, 11 and 22 years after the spill (1994) were compared to find out the rate of natural recovery of the ecosystem after oil decontamination of bottom sediments. The concentrations of fifteen trace metals (Al, Cr, Fe, Co, Ni, Cu, Zn, As, Mo, Cd, Sb, Pb, U, Bi, Th) were analyzed in the tissues (muscle) of three fish species. The concentrations of Al (3-309 mg/kg), Cr (0,1-3,71 mg/kg), Fe (8,6-317 mg/kg), and Cu (0,09-99 mg/kg) in fishes from polluted lake resulted in most cases higher than reference thresholds. Quantitative and qualitative indicators of aquatic invertebrates from polluted lake reach those one of unpolluted lake but do not fully recover 22 years after the spill, despite that oil concentration in water column and in bottom sediments was lower than reference tresholds. We conclude that natural recovery rate of aquatic freshwater ecosystems in northern regions after oil pollution is extremely low. The purification of water and bottom sediments of oil-polluted northern water bodies is necessary for stimulation of ecosystem restoration.

Metagenomic profiling for assessing microbial diversity and microbial adaptation to degradation of hydrocarbons in two South African petroleum-contaminated water aquifers

Biodegradation of hydrocarbons by indigenous populations of microorganisms found in petroleum-contaminated water sources represents one of the primary mechanisms by which petroleum and other hydrocarbon pollutants are eliminated from the aquatic environment. The identification of these microorganisms, which have capabilities to convert the majority of toxic hydrocarbons into compounds that are less harmful for end-users, is therefore crucial for bioremediation purposes. The aim of this study was to profile the microbial diversity of two South African petroleum-contaminated water aquifer sites and to determine the microbial adaptation to hydrocarbon degradation using a metagenomics approach. The sequenced samples revealed that protozoa (62.04%) were found to be the most dominant group, followed by fungi (24.49%), unknown (12.87%), and finally other sequences such as Animalia and plantae which were <(0.10%) domains in the first oil-polluted aquifer site. In the second site, protozoa (61.90%), unknown (16.51%), fungi (11.41%) in that order. According to the classification at the genus level, the dominant group was Naegleria (15.21%), followed by Vorticella (6.67%) as the only ciliated protozoan genus, other species such as Arabidopsis (2.97%), Asarum (1.84%) Populus (1.04%) were significantly low and drastically lower in the first site. Regarding the second site, the dominant group was Naegleria (18.29%) followed by Colpoda (9.86%) with the remainder of the genera representing <2%. Overall results demonstrated the ability of various groups of microorganisms to adapt and survive in petroleum oil-polluted water sites regardless of their respective distributions and this can be explored further for their role in bioremediation and environmental management.

The long-term prediction of the oil-contaminated water from the Sanchi collision in the East China Sea

The condensate and bunker oil leaked from the Sanchi collision would cause a persistent impact on marine ecosystems in the surrounding areas. The long-term prediction for the distribution of the oil-polluted water and the information for the most affected regions would provide valuable information for the oceanic environment protection and pollution assessment. Based on the operational forecast system developed by the First Institute of Oceanography, State Oceanic Administration, we precisely predicted the drifting path of the oil tanker Sanchi after its collision. Trajectories of virtual oil particles show that the oil leaked from the Sanchi after it sank is mainly transported to the northeastern part of the sink location, and quickly goes to the open ocean along with the Kuroshio. Risk probability analysis based on the outcomes from the operational forecast system for years 2009 to 2017 shows that the most affected area is at the northeast of the sink location.

Biosorbents and biologically active compounds in biotechnologies for rehabili-tation of oil-polluted soils and water basins of apsheron peninsula

В статье рассматриваются проблемы загрязнения нефтью и нефтепродуктами территории Апшеронского полуострова, очистки экосистем и повышения их эффективного плодородия. Изучена возможность получения нефтесорбентов на основе биогумуса – продукта переработки органических отходов дождевыми червями, а также цеолитов. Для улучшения экологической обстановки предлагается разработка биопрепаратов с использованием биогумуса и цеолита.

Graphene deposited onto aligned zinc oxide nanorods as an efficient coating for headspace solid-phase microextraction of gasoline fractions from oil samples

The content of gasoline fraction in oil samples is not only an important indicator of oil quality, but also an indispensable fundamental data for oil refining and processing. Before its determination, efficient preconcentration and separation of gasoline fractions from complicated matrices is essential. In this work, a thin layer of graphene (G) was deposited onto oriented ZnO nanorods (ZNRs) as a SPME coating. By this approach, the surface area of G was greatly enhanced by the aligned ZNRs, and the surface polarity of ZNRs was changed from polar to less polar, which were both beneficial for the extraction of gasoline fractions. In addition, the ZNRs were well protected by the mechanically and chemically stable G, making the coating highly durable for use. With headspace SPME (HS-SPME) mode, the G/ZNRs coating can effectively extract gasoline fractions from various oil samples, whose extraction efficiency achieved 1.5-5.4 and 2.1-8.2 times higher than those of a G and commercial 7-μm PDMS coating respectively. Coupled with GC-FID, the developed method is sensitive, simple, cost effective and easily accessible for the analysis of gasoline fractions. Moreover, the method is also feasible for the detection of gasoline markers in simulated oil-polluted water, which provides an option for the monitoring of oil spill accident.

Femtosecond laser fabrication of robust underwater superoleophobic and anti-oil surface on sapphire

Due to the presence of unique micro/nanostructures on the surface, fish’s scale exhibits underwater superoleophobicity and keeps clean even in oil-polluted water. Inspired from this, we propose a facile method for the fabrication of underwater superoleophobic and anti-oil sapphire surface with line-patterned nanostructures by femtosecond laser. The as-prepared surface shows great superoleophobicity that the oil contact angles can reach up to 153° for 1, 2-dichloroethane droplets in water and low oil-adhesion. At the same time, the relationship between the microgrooves’ period and surface wettability is studied, and the results indicate that the underwater superoleophobicity and low oil-adhesion can be achieved using a wide range of processing parameters. Meanwhile, the obtained surface is demonstrated to exhibit excellent stability. Moreover, the self-cleaning anti-oil ability of the as-prepared surface is conducted, and the potential mechanism of which is discussed. This technique has potential applications for the fabrication of underwater oil repelling devices and microfluidics.

TOXICOLOGICAL ASSESSMENT OF BIO PREPARATION OILDESTRUCTOR «LENOIL»® – NORD, SHP

Based on experimental results, toxicological assessment of the biological product oil-destructor «Lenoil»® – NORD, SHP is reported.. The biological product is intended for cleaning of oil-polluted soils and water objects at low positive temperatures. It was found out that the median lethal dose (LD50) at intragastric intake amounts to more than 5000 mg/kg, therefore the biological product refers to hazard class 4 (low hazardous substances). The biological product does not cause signs of irritation of respiratory tracts, but is able to induce slight irritation of eye mucous membranes and skin ( repeated applications).The biological product has no sensitizing action when reproducing a delayed-type hypersensitivity reaction. The biological product oil-destructor “Lenoil»® – NORD, SHP can be used for its intended purpose, i.e. to accelerate the destruction of oil and petroleum products during the remediation of oil-contaminated sites. At work the personnel must be provided with special clothing and personal protective equipment and observe hygiene and sanitary norms.

A novel hierarchical hollow SiO2@MnO2 cubes reinforced elastic polyurethane foam for the highly efficient removal of oil from water

Oil-polluted water has become a worldwide problem due to ever-increasing industrial oily wastewater as well as the frequent oil spill accident. A superior oil adsorbing material capable of separating oil–water mixtures efficiently, especially with a high oil adsorption capacity and mechanical strength, is urgently desired. Here, we report a novel strategy of preparing composite foams with hierarchical porous structures for effective oil/water separation and selective oil adsorption. The composite polyurethane foam is synthetized by a facile one-step foaming technology, which uses hierarchical hollow SiO2@MnO2 cubes to modify the inner structures of composite polyurethane foam. The incorporation of hierarchical hollow SiO2@MnO2 cubes into the foam could not only improve the morphologies, specific surface areas and hydrophobic properties but also enhance the adsorption capacity and mechanical properties. The as-prepared composite PU foam is put into the oil/water mixture to adsorb oils, and the adsorbed oils can be recovered simply by squeezing oil from composite PU foam. The resulting composite PU foam exhibits high oil adsorption capacity, high selectivity and oil adsorption capacity for carbon tetrachloride was measured to be 31.6g/g. Also, the composite PU foam shows excellent elasticity and the height of the composite PU foam decreased from 100% to 94% after 30 compressing–releasing cycles. Furthermore, the as-prepared composite PU foam exhibits the high reusability and durability by being reused for oil–water separation for 10 cycles without losing its hydrophobicity, which makes it a good candidate for industrial oil-polluted water treatments and oil spill cleanup.