Oil Removal Research Articles

Treatment of greywater coming from a food court using adsorption and advanced oxidation processes

The increase in the demand for water has recrudesced water scarcity in several places of the world, which has been intensified by the lack of rainfall, generating a water crisis, being very important to evaluate the treatment to allow the reuse of greywater. This is the first study focused on the removal of pollutants present in greywater using a pretreatment system based on ozone and solar irradiation. A series of treatments were addressed to evaluate the depuration of greywater coming from the dishwashing of a university dining hall. Notable findings of the study include several aspects such as a very high colour removal using sedimentation and, filtration and flotation process, with an overall colour removal of 91.8 %. The adsorption process removed a higher amount of surfactants with dried compost as adsorbent compared to fly ash or zeolite, with surfactant removal rates of 50.8 %, 7.8 %, and 9.0 %, respectively. Eliminating oil and grease from the greywater was studied with a solar photoreactor coupled with an ozonation process and configured in different ways. When ozone was incorporated into the vertical ozonation tube, and greywater was pumped to mix it with the ozone gas to pump the resulting mix to the borosilicate tube, oil and grease removal was 84.1 %. These treatment processes offer an effective solution for removing pollutants present in greywater; however, further studies and optimisation of operational conditions are required to enhance the efficiency of the treatment.

Amine grafted graphene oxide embedded in polyamide membranes for simultaneous removal of oil, metals, and salts from oily water

As a result of the economic growth and the emergence of industrialization in most economies, water purification has gained increased significance. The nanocomposite nanofiltration membranes can remove salts, hydrocarbons, and environmental pollutants. However, the surface wettability of the membrane materials is crucial since they are utilized to separate emulsified oil/water mixtures. In this study, the polyvinylidene fluoride support membrane was successfully modified to a hydrophilic state in this instance via dip single-step coating by modifying graphene oxide (GO) with (3-aminophenyltriethoxysilane)-trimesic acid-melamine (GO-APTES-TA-MM) polyamide. The separation efficiency and antifouling properties were evaluated by analyzing the flux using a membrane cell tester machine. Scanning electron microscopy (SEM) was used to confirm the morphology of the membrane and EDX was employed to characterize the modified membrane before and after separation testing. The membrane shows good rejection of organic pollutants including pentane, isooctane, toluene, and hexadecane, attaining a removal of >90 % of heavy metals such as strontium, lead, and cobalt, and 86 % rejection of salt ions SO42−, and 42 % for Mg2+. According to the findings, the membrane can be a good choice for simultaneous treatment of wastewater containing a mixture of metal ions, hydrocarbons, and salt mixes from oily water.

Removal of Oil and Grease from Oily Kitchen Wastewater by Using Raw Kapok as a Potential Adsorbent

Oil and grease are one of the elements that are poisonous and easily pollute the environment, especially water and soil. Adsorption techniques use natural adsorbents that do not damage or pollute the environment. The raw kapok was chosen as an adsorbent because it is a technology to overcome the problem of oil produced globally. The experiment was conducted with two types of dosage which are 5g and 15g of raw kapok to absorb the oil and the results stated that raw kapok can absorb the cooking oil that is still not used more than the cooking oil that has been used. Due to the density of the oils, it affects the ability of raw kapok to absorb and hold oil. In addition, this absorbed oil restores several water parameters such as dissolved oxygen (DO), pH, temperature and turbidity.

Accuracy of using the axial length of the fellow eye for IOL calculation in retinal detachment eyes undergoing silicone oil removal

PurposeEvaluate whether the axial length of the fellow eye can be used to calculate the intraocular lens (IOL) in eyes with retinal detachment.DesignRetrospective, consecutive case series.MethodsOur study was conducted at...

Cement based nanofiltration membrane of porous boron nitride and graphene oxide for effective oil/water separation

The development of effective filters for crude oil/water separation presents a critical environmental challenge in the face of oil spills. Porous membrane separation stands as a vital technique for removing organic solvents, oils, and dyes from water. In this study, we designed and fabricated a nanofiltration membrane composed of graphene oxide (GO) and boron nitride (BN) incorporated into a cement-based matrix to enhance the selectivity and efficiency of unidirectional flux transportation. The integration of GO, with its rich functional groups, and BN, known for its hydrophobic properties, within the cement matrix, resulted in an improved water permeation rate. Moreover, the inclusion of BN flakes in the cement matrix significantly enhances its mechanical strength, reaching up to 15.93 MPa (∼35 % greater than pristine cement), establishing it as a robust nanofiltration membrane for simultaneous flux enhancement and water purification. This innovative filter demonstrated remarkable separation efficiency, achieving up to 99 % oil removal while allowing the passage of water. To gain a deeper understanding of our experimental findings, we conducted ab initio investigations into the adsorption behavior of water and oil components, including ethanethiol, thiophene, and toluene molecules, on h-BN, GO, and their defective structures (Stone-Wales defect). Our results affirm that porous h-BN and GO nanosheets, characterized by their high specific surface areas, exhibit remarkable sorption capabilities. This nanoengineered membrane showcases substantial adsorption capacity alongside physisorption characteristics suitable for recycling, thereby holding significant potential for the development of functional porous structural materials in the realm of high-performance, cost-effective, and environmentally sustainable water treatment solutions.

Prognostic Factors for Recurrent Rhegmatogenous Retinal Detachment after Silicone Oil Removal.

To investigate the prognostic factors for recurrent rhegmatogenous retinal detachment following silicone oil removal. This retrospective review included 147 consecutive patients with rhegmatogenous retinal detachment treated with silicone oil tamponade at a high-volume referral-based tertiary hospital between January 2012 and May 2022. All patients underwent follow-up for a minimum of 6 months after subsequent silicone oil removal. The primary outcome measure was the rate of recurrent retinal detachment following silicone oil removal, and the secondary outcome was best-corrected visual acuity after silicone oil removal. The mean silicone oil tamponade duration was 4.7 ± 5.01 months (range, 1-38 months; median, 3 months), and the recurrent retinal detachment rate after silicone oil removal was 15.6%. Logistic regression analysis revealed that argon endolaser photocoagulation during silicone oil removal (odds ratio [OR], 0.309; 95% confidence interval [CI], 0.106-0.898; p = 0.031) was associated with a lower rate of anatomical success after silicone oil removal. Demographics, preoperative ocular characteristics, proliferative vitreoretinopathy, previous scleral encircling or buckling, previous retinectomy, concomitant phacoemulsification, duration of silicone oil tamponade, and gas tamponade after silicone oil removal were not significantly associated with recurrent retinal redetachment after silicone oil removal. Duration of silicone oil tamponade (OR, 1.226; 95% CI, 1.073-1.402; p = 0.003) and recurrent retinal detachment after silicone oil removal (OR, 3.400; 95% CI, 1.311-8.817; p = 0.012) were associated with poor visual outcomes after silicone oil removal. Among all factors examined in this study, including the duration of silicone oil tamponade, laser retinopexy was the only significant prognostic factor for recurrent retinal detachment after silicone oil removal. A longer duration of silicone oil tamponade was associated with worse visual outcomes and a lower rate of visual improvement after silicone oil removal.

Probe into a novel surfactant-free microemulsion system of ethylene glycol monobutyl ether + water + diesel for crude oil removal and recovery from oily sludge

A novel surfactant-free microemulsion (SFME) system was proposed in this study, and applied in the crude oil removal and recovery from oily sludge (OS). Based on an investigation of the SFME phase behavior and solution properties, a complete ternary phase diagram was constructed. The SFME with three-liquid phase equilibrium (Winsor III type) was selected for the treatment of OS to achieve simultaneous efficient removal (up to 95.1 %) and recovery (up to 83.2 %) of crude oil. The SFME could be reused continuously for OS treatment without purification. The removal efficiency could still keep >75.9 % after 5 times of reuse, showing high reusability. The detached crude oil could be automatically recovered based on the phase equilibrium principle without additional separation. In the washing experiments, single-factor and multi-factor orthogonal tests were applied to investigate the effects of different experimental conditions on oil removal efficiency and determine the optimal experimental scheme. The treated OS was sufficiently decontaminated according to the morphology, composition, and properties analysis by scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and contact angle. The composition of the recovered crude oil was identical to that of commercial crude oil according to gas chromatography–mass spectrometry analysis, showing a high recovery value. The kinetic analysis revealed that crude oil desorption experienced three main stages: membrane diffusion, intra-particle diffusion and surface desorption, and identified the chemisorption was the main interaction between the oil–soil. Finally, the mechanism of SFME action was assessed for dissolution and activation based on ultra-low IFT.

Simulation and experimental study on precise aeration and electric field for synergistic demulsification of emulsified oil

Numerical simulations of the deformation, aggregation, and migration processes of emulsified oil droplets under the influence of a multiphase field were conducted using COMSOL software. Combined with laboratory experiments, an existing process was improved and optimized by introducing the concept of "precise aeration." The results indicate that aeration can enhance the efficiency of electrochemical demulsification, with the gas field accelerating the deformation, aggregation, and migration processes of the oil droplets. Leveraging the numerical simulation results, laboratory experiments were conducted to optimize the aeration intensity and duration, which were reduced to 1.5 L/min and 60 min. At this point, the oil content and chemical oxygen demand (COD) of the emulsified oil wastewater were only 4.98 mg/L and 101 mg/L, respectively. The demulsification mechanism was analyzed, revealing that under the combined action of the electric field and gas field, oil droplets underwent a polarization reaction and were aggregated into larger droplets. Aeration expedited the weakening of the mechanical strength at the oil-water interface of the droplets, which significantly improved the demulsification, coalescence, and flotation removal of the emulsified oil droplets. This study holds significant importance for the process improvement and mechanistic analysis of electrochemical demulsification for oil removal.

Polystyrene-reduced graphene oxide composite as sorbent for oil removal from an Oil-Water mixture

This study enhanced the adsorptive capacity of polystyrene (PS) by infusing reduced graphene oxide (rGO) nanoparticles obtained from the synthesis of graphene oxide to produce PS-rGO composites via electrospinning method. Physicochemical characterization of as-synthesized rGO and PS-rGO were carried out through scanning electron microscopy, N2 physisorption among others. Oil sorption performance of synthesized rGO in crude oil, vegetable oil, fresh engine oil and used engine oil are 130.96 g/g, 121.77 g/g, 105.01 g/g and 100.56 g/g. Oil sorption capacities of electrospun pure PS in crude oil, vegetable oil, fresh engine oil and used engine oil were 46.32 g/g, 38.54 g/g, 35.14 g/g and 32.57 g/g and those of PS-rGO infused with 4 wt% of rGO were found to be 105.52 g/g, 98.86 g/g, 86.25 g/g and 83.47 g/g for crude oil, vegetable oil, fresh engine oil and used engine oil samples respectively. Pseudo second order (PSO) kinetic model fits the sorption data of the four oil samples on the four composite sorbents produced. Intra-particle diffusion (IPD) model evidently showed that sorption of the four oil samples on the four composite sorbents, occurred in three (3) phases. Composites demonstrate high oil adsorption capacity, and are reusable upto three sorption–desorption cycles.

Inside-out templating: A strategy to decorate helical carbon nanotubes and 2D MoS2 on ethyl cellulose sponge for enhanced oil adsorption and oil/water separation

Ethyl cellulose (EC)-based composite sponges were developed for oil spillage treatment. The EC sponge surface was decorated with helical carbon nanotubes (HCNTs) and molybdenum disulfide (MoS2) (1 phr) using the inside-out sugar templating method. The inside surface of a sugar cube was coated with HCNTs and MoS2. After filling the sugar cube pores with EC and the subsequent sugar leaching, the decorating materials presented on the sponge surface. The EC/HCNT/MoS2 sponge had a high level of oil removal based on its adsorption capacity (41.68 g/g), cycled adsorption (∼75–79 %), separation flux efficiency (∼85–95 %), and efficiency in oil/water emulsion separation (92–94 %). The sponge maintained adsorption capacity in acidic, basic, and salty conditions, adsorbed oil under water, and functioned as an oil/water separator in a continuous pump-assisted system. The compressive stress and Young's modulus of the EC sponge increased following its decoration using HCNTs and MoS2. The composite sponge was robust based on cycled compression and was thermally stable up to ∼120 οC. Based on the eco-friendliness of EC, the low loading of HCNTs and MoS2, and sponge versatility, the developed EC/HCNT/MoS2 sponge should be good candidate for use in sustainable oil adsorption and separation applications.

The methods for improving the biodegradability of oily sludge: a critical review.

Biological degradation method, as an environmentally friendly, low-carbon, and clean pollution treatment technology, is widely used for the harmless disposal of oily sludge. The biodegradability of oily sludge with stable emulsification system, high oil, and water content is poor. Therefore, it is necessary to pre-treat the oily sludge to improve its biodegradability, including recover the petroleum resources and remove heavy metals and bio-toxic organic matters. This review systematically summarizes five oily sludge treatment methods and their influences on sludge biodegradability, including pyrolysis, chemical hot washing, solvent extraction, chemical oxidation, and hydrothermal. Pyrolysis at temperatures above 750 °C produces high molecular weight polycyclic aromatic hydrocarbons, chemical hot washing and chemical oxidation would cause secondary pollution, solvent extraction method could not be applied due to the high cost and high toxicity of the extractant, and the oil removal of hydrothermal method is inefficient. Additionally, the principles, advantages, and disadvantages of those treatments and the factors affecting microbial degradation were analyzed, which provide the development direction of pretreatment technology to improve the biodegradability of oily sludge.

Remediation of oil-polluted soil using anionic and non-ionic composite biosurfactants

ABSTRACT Petroleum hydrocarbons as pervasive pollutants pose a significant threat to soil ecology and human health. Surfactant washing as an established technique can effectively remediate soils contaminated by hydrocarbons. Biosurfactants, which combine the properties of surfactants and environmental compatibility, have attracted increasing interest. However, due to the high production cost of biosurfactants, their practical application is restricted. This study addressed these limitations by selecting two biosurfactants, β-cyclodextrin (C1) and sodium carboxymethyl cellulose (C2), and developed a promising cleaning agent formula through compounding and the addition of suitable additives. When the volume ratio of C1 to C2 was 8:2 and an 8 g/L mixture of sodium humate and sodium carbonate electrolyte was added, the surfactant system’s surface tension reached a minimum, yielding optimal oil removal. The formation and synergistic behaviour of mixed micelles of surfactants were explained using ideal solution theory and the Rubingh model. By optimising the oil washing process parameters – normal temperature of 25 °C, pH 11, washing time of 2 h, solid–liquid ratio of 1:5, and oscillation frequency of 200 r/min – the oil removal rate achieved 76%. This cleaning agent, characterised by low production cost, straightforward application, environmental compatibility, and rapid, significant cleaning effect, shows potential for field-scale purification of petroleum-contaminated soil.

Transcorneal Vitrectomy in Eyes with Regressed Retinoblastoma

Purpose: Current treatments for retinoblastoma facilitate globe salvage but can result in vitreoretinal disorders that may require surgery. There is controversy on surgical approaches in eyes with retinoblastoma. Here we describe a transcorneal vitrectomy approach that avoids the use of chemotherapy or cryotherapy. Methods: Retrospective chart review was performed on five consecutive patients with regressed retinoblastoma for >12 months (Group D/ct2b) at Children’s Hospital Los Angeles who had vitrectomy between November 2022 and December 2023. Results: Five patients underwent 8 vitrectomies for various indications including IOL fibrosis, vitreous hemorrhage, cataract, retinal detachment, and silicone oil removal. Mean age at first vitrectomy was 6.2 years (range: 2-9 years); mean time from last retinoblastoma treatment was 50.4 months (range: 20-82 months). Radially oriented corneal incisions were made with the 23-gauge or 25-gauge trocar system and the Versa HD LenZ (Oculus) was utilized with the RESIGHT (Zeiss) for top-down visualization. Neither chemotherapy nor cryotherapy were utilized. Wounds were sutured parallel to the limbus with 10-0 polyglactin 910 suture (Vicryl, Ethicon), and a final water rinse was performed to lyse any potential retinoblastoma cells. Surgical objectives were achieved, vision remained stable, and no retinoblastoma spread was noted with a mean follow-up of 7.6 months (range: 3-12 months). Conclusions: This vitrectomy technique for eyes with regressed retinoblastoma permits top-down viewing with the Versa HD LenZ. Radial placement of corneal wounds avoids suturing through the uveal tract, and a postsurgical water rinse lyses any retinoblastoma cells. This approach may obviate the need for chemotherapeutics or cryotherapy.

Degradation of oily sludge by microwave–ultrasound-immobilized bacterial agent technique

In order to more effectively remove petroleum hydrocarbons from oily sludge, in this study, we proposed a microwave ultrasound immobilized bacterial agent oily sludge degradation technology, and through experiments to explore the various factors affecting the degradation, the best process conditions were obtained to improve the oil degradation rate in oily sludge. The results of microwave ultrasonic pretreatment showed that under the optimized conditions, the maximum removal rate of oil and gas substances was 53.23%, and the crude oil recovery rate was 31.03%. The oil removal effect was significantly improved compared with the single treatment and the treatment without optimized reaction conditions. The results of further treatment with immobilized bacterial agent showed that the highest oil removal rates of biochemical sludge and oil sludge scum were 92.04% and 35.56%, respectively, after the optimal compound ratio of composite bacteria and the optimized preparation conditions of immobilized bacterial agent were used, and the oil removal effect was further improved. This study proved that microwave and ultrasound combined with a variety of microbial technologies can effectively improve the removal rate of petroleum hydrocarbons in oily sludge after optimizing the process conditions.

Coconut shell-derived green synthesised carbon nanotubes for clean-up of crude oil spills

Abstract The global economy has led to an increase in oil transportation and exploitation, posing a threat to aquatic and terrestrial ecosystems. Crude oil spilled water purification is a major challenge worldwide. Researchers are focusing on finding adsorbents that improve oil adsorption capability. In the present study the adsorption of crude oil using synthesized carbon nanotubes (CNTs) prepared from coconut shell was investigated by batch adsorption experiments under varying parameters (adsorbent dosage and contact time) after analytical techniques (UV–vis, FTIR and SEM) confirmed the formation of the CNTs. The morphological modification significantly increased the hydrophobicity of the adsorbent, thus creating a synthesized CNTs with a much better adsorption capacity for crude oil removal having a maximum adsorption capacity of 4855.8 mg/g. The experimental results showed that the percentage of crude oil removal increased with an increase in adsorbent dosage and the contact time respectively. According to the correlation coefficient (R 2 = 0.9801) value obtained from the adsorption isotherm investigations, the isotherms were found to fit the Freundlich isotherm somewhat better than the Langmuir isotherm model, which is consistent with the findings reported in the literature. These findings have made the synthesised CNTs an attractive, useful, and environmentally friendly adsorbent for controlling crude oil spill.

Redox-switchable microemulsions with efficient phase separation and surfactant recycling

HypothesisSwitchable microemulsions (MEs) are those capable of adaptively responding to the action of internal or external stimuli. For redox-switchable MEs to obtain high-efficiency phase separation and surfactant recycling, it may be one of the keys to adequately turn off the interfacial activity of surfactants and reduce the solubility of the closed surfactants in the oil phase. ExperimentsMonophasic MEs consisting 11-butylselanyl-undecyl sulfate sodium (C4SeC11SO4Na), n-butanol, n-octane, and water were fabricated using the pseudo-ternary phase diagram method. Their structural features and droplets size were characterized by conductivity, dynamic light scattering (DLS) and cryogenic transmission electron microscopy (cryo-TEM), respectively. The redox response of MEs was studied using a combination of visual observations and DLS, cryo-TEM, nuclear magnetic resonance (NMR) and thin-layer tomography. The efficient recycling of C4SeC11SO4Na from a well-emulsified eluent is conceptually demonstrated. FindingsThe reversible transition between C4SeC11SO4Na and C4SeOC11SO4Na is achieved under the alternating action of H2O2 and N2H4, by which C4SeC11SO4Na-based monophasic MEs are able to efficiently demulsify and regenerate, respectively, regardless of their type. After H2O2-induced demulsification of the MEs, C4SeOC11SO4Na can be efficiently recycled with the water phase. We hope that such a redox-switching method may benefit some technological applications. For example, it offers exciting possibilities for simultaneous recycling C4SeC11SO4Na and removal of oil from a well-emulsified eluent. Around 97.1 ± 0.3 % of C4SeC11SO4Na could be recycled over five cycles with no apparent loss. After a simple and conventional treatment with anion-exchange resin and active carbon, the total organic carbon and chemical oxygen demand of the waste water were 17.4 ± 2.8 and 26.2 ± 1.4 mg/L, respectively.

The efficiency removal of oil in water (OIW) by application of milliscale air bubbles

The efficiency removal of oil in water (OIW) by application of milliscale air bubbles

Application of Nanobubbles in Floating Kinetics Models for Efficient Oil Removal from Produced Water

Application of Nanobubbles in Floating Kinetics Models for Efficient Oil Removal from Produced Water

High-performance hydrophobic aerogel based on nanocellulose, graphene oxide, polyvinyl alcohol, and hexadecyltrimethoxysilane: Structure, properties, and applicability

The most prevalent kinds of contaminants found in water sources are oil and organic substances, which are often present in either spilled or emulsified states. Due to the vast surface area and porous structure, nanocellulose aerogel is an environmentally benign material widely employed for its efficacy in adsorbing oils and organic pollutants. In this study, an aerogel composed of nanocellulose (CNF), graphene oxide (GO), and polyvinyl alcohol (PVA), subsequently modified with hexadecyltrimethoxysilane (HDTMS), exhibited a well-defined structure and demonstrated proficient removal of waste oil and certain organic solvents from water at high speed. By a simple and cheap preparation method from solution mixing and freeze-drying, the resultant aerogel has a high porosity of 97.26 %, a light density of 0.0036 g/cm3, a mesoporous structure with a mean pore diameter of 3.5 nm, and a surface area of 15.717 m2/g. Aerogel exhibits pronounced superhydrophobic behavior, achieving a contact angle of up to 152°, thereby substantially impeding water permeation through its structure in experimental assessments of selectivity and efficacy in separating oil-water mixtures. According to Langmuir isotherm model, DO adsorption occurred in a monolayer. CNF/GO/PVA/HDTMS aerogel exhibited a maximum adsorption capacity of 322.58 mg/g, with the pseudo-second-order model effectively representing this adsorption process. Furthermore, the CNF/GO/PVA/HDTMS aerogel displays a strong adsorption capability towards oils and organic solvents, with a range of 10–25 times the original volume of the aerogel. Another feature of the resultant aerogel is its good deemulsion ability on both water-in-oil and oil-in-water emulsions. The pump extraction method is more effective than the extraction method in oil recovery and reuse of the aerogel. The results obtained in the study show a potential environmentally friendly material for the treatment of oily and organic solvent wastewater from industries.

Oil Removal Technology for Water Injection in Low-Permeability Reservoirs: A Micro-Vortex Flow Approach

Oil Removal Technology for Water Injection in Low-Permeability Reservoirs: A Micro-Vortex Flow Approach