Oil Adsorption Research Articles

Fabrication, characterization, and in vitro digestion of gelatin/gluten oleogels from thermally crosslinked electrospun short fiber aerogel templates

In this work, the electrospun short fiber-based oleogels (ESFO) were formed by thermal crosslinking. Gelatin and gluten nanofibers were obtained via electrospinning, then homogenized and transformed into short fiber dispersions. Through freeze-drying, electrospun short fiber-based aerogel (ESF-A) templates were obtained for oil adsorption. All ESF-A exhibited the micromorphology of loose fibrous pore structure and prominent changes of characteristic peaks in the thermal and infrared analyses. Moreover, the highly crosslinked templates owned excellent hydrophobicity and mechanical performances (elastic modulus: 0.25 kPa, yield strength: 14.56 kPa, compressive strength: 52.54 kPa, and the final compression recovery: 91.27%). Meanwhile, the oil adsorption/oil holding capacity could reach 76.56 g/g and 80.04%, respectively. Through thermal crosslinking, ESF-O presented good and controllable rheological/in vitro digestion properties, which were further confirmed by PCA analysis. According to different application conditions, ESF-O properties could be adjusted by different degrees of fiber addition or thermal crosslinking.

Efficient adsorbents for oil spill removal using a cellulose acetate-based natural fibers developed by zinc oxide bionanocomposites

Due to the rising use of crude oil and its derivatives, there is a growing apprehension over the contamination of aquatic environments by oil. Hence, it is important to devise efficient methodologies and substances for the purpose of cleansing and eliminating oil from the surroundings. This work aimed to create an environmentally acceptable oil sorbent by combining cellulose acetate (CA) biopolymer with varied amounts of natural date palm fiber (DPF) (10, 20, and 30 wt %) and modifying the surface with ZnO nanoparticles at various ratios (2, 5, 10, and 20 wt %). This study examines the adsorption capabilities of untreated diesel particulate filters (DPF) and modified DPFs for diesel oil. The results showed that the experimental maximum sorption capacity of the composite material, DPF-CA/ZnO, made using CA polymer with 30 wt % DPF and 10 wt % ZnO nanomaterials, was significantly higher (66.4 mg/g) than that of the raw DPF (26.5 mg/g). The fabricated materials were characterized using scanning electron microscopy, energy dispersive X-ray analysis (SEM-EDX), transmission electron microscopy (TEM), thermogravimetric analysis (DTA-TGA), Fourier transform infrared spectroscopy (FTIR), and Brunauer–Emmett–Teller analysis (BET). Isothermal studies demonstrated that the adsorption of oil followed the Langmuir and Dubinin‐Radushkevich models, with R2 values of 0.99 and 0.93, and the calculated maximum adsorption capacities (qcal) from these models were 64.6 mg/g and 65.7 mg/g, respectively. Furthermore, the kinetic studies revealed that oil adsorption obeyed pseudo-second-order kinetics infer from R2 values 0.99 and (qcal) 66.7 mg/g aligning closely with (qexp). In addition, the sorption efficiency of this sorbent after five sorption cycles indicated good reusability. This study successfully employed a DPF to efficiently remove oil from water, presenting a commercially viable and environmentally friendly solution.

Biomimetic dendritic‐networks‐inspired oil-water separation fiber membrane based on TBAC and CNC/PVDF porous nanostructures

Inspired by the multi-level structure of trees in nature, using cellulose nanocrystals/polyvinylidene fluoride (CNC/PVDF) fibers as the support layer and CNC/PVDF/organic branched salt (TBAC) fibers as the filtering layer, to construct oil–water separation membrane with tree-like structure. The membrane's surface (nano spherical) and internal (interconnected pores) structures were regulated by phase separation of CNC induced. The high conductivity of TBAC was utilized to construct branched fibers (d = 53.3 nm) on the backbone fibers (d = 1.2 μm). The impact of TBAC on the microstructure, wetting behavior, and oil–water separation performance of membranes was investigated. Note, TBAC concentration was 0.02 mol/L, the membrane exhibits a highly porous dendritic network structure (with porosity of 85 % and pore size of 6.1 nm), and outstanding wetting properties (water contact angle underoil ˃ 150°). This distinctive structure endows membranes with a high oil adsorption capacity (64.1 g/g of engine oil), oil flux (22873 L/m−2h−1 of toluene). Following ten testing cycles, the toluene adsorption capacity remains at 83.1 % of the initial adsorption, while the separation flux of emulsion (5645 L/m−2h−1) remains nearly constant. Overall, successfully fabricating CNC/PVDF/T-0.02 fibers with a tree-like structure provides a novel approach to designing and developing efficient membrane separation materials.

Effects of the Mesoporous Filler and Oleophilic Property on the Tribological Behavior of Polyetheretherketone Composites.

Porous composites, such as polyimide and polyetheretherketone (PEEK) polymer composites, became more attractive as a result of excellent specific strength, lightweightness, and smart lubrication. However, revealing the influence of a porous filler on the friction behaviors of polymer composites remains a challenge. The current work examines the effects of the pore structure and wettability on the mechanical and tribological performances of polymer composites reinforced with fillers. Three kinds of particles (non-porous, porous, and oleophobic porous) act as fillers within PEEK, respectively. It was identified that adding porous zeolite particles into PEEK slightly decreased the mechanical property. The zeolite particles significantly increased the oil adsorption of the composite, leading to a significant increase in the friction coefficient at 10 wt % content. However, the friction coefficient of the PEEK composite filled with 20 wt % modified zeolite was relatively low as a result of the weak adsorption. The interface analyses indicated that the thickness of the oil film was controlled via porous structures, changing the lubrication regime of the tribopair. The reason is the appropriate adsorption of oil and the release of zeolite from the composites during the friction process. These results can offer technical guidance to control the friction behaviors of composites under oil-lubricating conditions by a porous particle and pore modification.

Alkaline solubilization of microalgal protein and its impact on the functional properties of protein extract

Microalgal alternative proteins are increasingly recognized as a sustainable and promising source for future food production. Despite the widespread use of alkaline solubilization in protein extraction, its influence on the functional properties of microalgal protein extracts has received limited attention. This study marks the pioneering effort to assess the impact of alkaline (NaOH) solubilization on both the extraction process and the functional properties of Chlorella vulgaris protein extract (CVPE) obtained through isoelectric precipitation. With the gradual escalation of alkaline concentration from 0 to 0.7 M, there was a notable improvement in protein extraction efficiency, increasing significantly from 6.22 % to 56.23 %. However, elevated NaOH concentrations resulted in protein degradation, as evidenced in SDS-PAGE studies. Alkaline solubilization exhibited a positive impact on various functional properties of CVPE. It enhanced solubility, water absorption capacity, foaming capacity and stability, as well as emulsifying activity and stability. However, there was a slight decrease in oil absorption capacity with increasing NaOH concentration. Notably, the maximum solubility, oil adsorption capacity, foaming capacity, and emulsion activity of CVPE were 2.3-, 1.8-, 2-, and 1.3-fold higher, respectively, than those of commercial soy protein isolate (SPI). This highlights the effectiveness of alkaline solubilization in modifying C. vulgaris protein and emphasizes the high potential of CVPE as a functional food ingredient.

Supercritical CO2 extrusion foaming of highly open-cell poly(lactic acid) foam with superior oil adsorption performance

Addressing marine oil spills and industrial water pollution necessitates the development of eco-efficient oil-absorbing materials. With increasing concern for the environment, there is a consensus to decrease the use of petroleum-based polymers. Herein, lightweight poly(lactic acid) (PLA) blend foams with varying thermoplastic polyurethane (TPU) content were fabricated via a solvent-free, eco-friendly supercritical carbon dioxide (scCO2) extrusion foaming technology. The incorporation of TPU significantly enhanced the crystallization rate of PLA, with the semi-crystallization time of PT30 and PT50 blends at 105 °C exhibiting a reduction of 77.2 % and 47.9 %, respectively, compared to neat PLA. The resulting foams exhibited an open-cell structure with excellent selective oil adsorption capabilities. Notably, the PT30 foam achieved a remarkable maximum expansion ratio of 36.0, while the PT50 foam attained the highest open-cell content of 96.2 %. The PT50 foam demonstrated an outstanding adsorption capacity, spanning from 4.7 to 18.8 g/g for diverse oils and solvents, with rapid adsorption kinetics, reaching 94.9 % of the equilibrium adsorption capacity for CCl4 within just 1 min. Furthermore, the PT50 foam retained 95.2 % of its adsorption capacity for CCl4 over 10 adsorption-desorption cycles. This study presents a scalable and sustainable approach for large-scale production of high-performance, bio-based foams, facilitating efficient oil-water separation.

Composite Materials Based on Waste Chicken Feather Fibers for Oil-Spill Management

ABSTRACT Oil spills remain one of the greatest man-made ecological threats, despite numerous advanced cleanup approaches. They still pose a major challenge in the search for materials and technologies that work as efficiently and sustainably as possible. Promising natural materials include poultry feathers, which are produced in large quantities every day as a byproduct of the meat industry. In this study, the influence of different forms of absorbents (loose feathers, pillows, and sheets) based on chicken feathers and the addition of an inorganic absorbent, sepiolite, on their absorption capacity was investigated. The chemical and physical surface properties, like morphology, chemical composition, zeta potential, surface free energies and oil absorption capacities were analyzed. The Gibbs free energy of immersion wetting with oil and the work of adhesion of the adsorbents, calculated based on contact angle measurements, were confirmed by the tests of adsorption capacities according to the ASTM 726–12 standard. The results showed that pure loose feathers have the highest oil adsorption capacity, while feather pillows have only half, and composite sheets have only a quarter of this capacity. The addition of inorganic adsorbent sepiolite did not increase the absorption capacity of the composites.

Synthesis and application of dual-functional sorbent SBA-15-Fe3O4-PDA-ODA for removing both water soluble and insoluble pollutants

In this study, inorganic-organic hybrid sorbent SBA-15-Fe3O4-PDA-ODA with functional groups having affinity for both water-soluble and insoluble pollutants was synthesized for treatment of wastewater where Malachite Green (MG) dye and motor oil coexist. In order to enhance the specific interactions between the sorbent and dye via functional groups of polydopamine (PDA), Fe3O4 nanoparticles were encapsulated with SBA-15 and surface functionalization with PDA was accomplished and then the surface of Fe3O4-SBA-15-PDA was modified with octadecylamine (ODA) to remove the oil present in the same environment with dye. While the SBA-15-Fe3O4-PDA-ODA directed to the aqueous phase by magnet provided MG removal thanks to the hydrophilic groups of PDA, it provided motor oil removal thanks to hydrophobicity of ODA when directed to the oil phase. 99.20 % dye removal and 9.24 g/g oil adsorption capacity were achieved from the environment where oil and dye were present together. Besides, the adsorption of MG on Fe3O4-SBA-15-PDA was searched at various pH, dye concentration, adsorbent dosage, and temperature in order to propose optimum experimental conditions for removal of dye and maximum adsorption capacity was determined as 95.83 mg g−1 at optimum conditions (10 mg adsorbent, 10 mg L−1 MG concentration, pH 9). Interaction mechanism between dye and Fe3O4-SBA-15-PDA was explained by studying the adsorption behavior of sorbent derived from the isotherm and kinetic results. The sorbents were characterized by FT-IR, XRD, SEM, N2-adsorption/desorption, water-contact-angle, and VSM measurements. SBA-15-Fe3O4-PDA-ODA sorbent was tested for three successive adsorption cycles for both dye and oil and eventuated insignificant loss in activity when they were recycled. Easy and low-cost fabrication protocol, controllable removal ability of dye and oil will facilitate its versatility in environmental cleanup process for water soluble and insoluble pollutants.

Green Strong Cornstalk Rind-Based Cellulose-PVA Aerogel for Oil Adsorption and Thermal Insulation.

Cellulose-based aerogel has attracted considerable attention for its excellent adsorption capacity, biodegradability, and renewability. However, it is considered eco-unfriendly due to defibrillation of agriculture waste and requires harmful/expensive chemical agents. In this study, cornstalk rind-based aerogel was obtained via the following steps: green H2O2/HAc delignification of cornstalk rind to obtain cellulose fibers, binding with carboxymethyl cellulose (CMC)/polyvinyl alcohol (PVA) and freeze-drying treatment, and hydrophobic modification with stearic acid. The obtained aerogel showed high compressive strength (200 KPa), which is apparently higher (about 32 kPa) than NaClO-delignified cornstalk-based cellulose/PVA aerogel. Characterization of the obtained aerogel through SEM, water contact angle, etc., showed high porosity (95%), low density (0.0198 g/cm-3), and hydrophobicity (water contact angle, 159°), resulting in excellent n-hexane adsorption capacity (35 g/g), higher (about 29.5 g/g) than NaClO-delignified cornstalk-based cellulose/PVA aerogel. The adsorbed oil was recovered by the extrusion method, and the aerogel showed excellent recyclability in oil adsorption.

Ultrastable superhydrophobic melamine sponge via a one-step aqueous solution-based approach for oil/water separation

In this study, an eco-friendly aqueous solution-dipping method was developed for the synthesis of an ultrastable superhydrophobic melamine sponge (MS). The MS exhibits not only a high oil adsorption capacity of 46.3–149.5 times of its own weight, but also a good reusability with a slight decrease in adsorption capacity after 20 absorption-desorption cycles. Moreover, the continuous separation of immiscible oils/organic solvents and water with vacuum assistance is also realized. Besides, the material also features with exceptional physicochemical stability and fire-retardant performance, enabling its potential applications in extreme environments (high temperature, strong wind and waves, strong acids and alkalis, UV radiation, etc.). The as-established synthesis pathway has its chance in simplifying the industrial fabrication processes of composited functional sponges.

Efficient cleanup of highly viscous spilled oil using a fast solar-heating and super hydrophobic sponge

A solar-heating sponge, in which the polypyrrole (PPy) coating plays the role of photothermal converter and carbon nanotubes (CNTs) act as the thermal conductor, was fabricated. The sponge can effectively convert sunlight into heat and fast conduct heat so that the temperature can rise to 80 °C within 30 s under 1 sun irradiation. Besides, the temperatures of the other parts rise synchronously with the top surface, unlike most reported sponges which had temperature differences between different parts. This advantage can avoid the decrease of diffusion rate of the oil in application. The sponge also exhibits super hydrophobility with a high water contact angle of 151.2°. The excellent solar-heating ability and hydrophobility make the sponge an efficient viscous oil adsorbent. The sponge can continuously and rapidly remove the spilled oil under solar irradiation. The coating composed of interconnected PPy nanosheets is firmly fixed on the surface of the elastic matrix via multiple H bonds. After 10 adsorption-desorption cycles, the adsorption capacity still maintains 97.2 %, without any change in hydrophobility. These advantages including fast solar-heating, super hydrophobility and high regenerability demonstrate that the sponge has great potential in oil spill treatment, especially highly viscous oils.

Bioinspired melt-blown fiber felt with flame retardancy for efficient oil spill remediation by solar-driven oil evaporation and adsorption

Confronted with rapid-spread river oil leaks and marine oil spills containing toxic and light fractions, conventional emergency response measures often fall short. This study proposes a solar-driven oil evaporation and adsorption (SOEA) strategy that efficiently addresses the challenges posed by toxic and light oils in rivers and oceans. Inspired by the self-protection and anti-fouling effects of fish scales, a photothermal oil-adsorbing felt with a biomimetic scale structure for efficient SEOA is constructed by decorating functional components onto the melt-blown fiber felt using scalable spraying technology. The rational integration of a dual-layer scale structure and functional constituents imparts stable superhydrophobicity, self-cleaning, flame retardancy, enhanced mechanical strength, and a higher oil adsorption capacity. Benefiting from the superior photothermal conversion, the solar-vapor conversion efficiency of the resulting P-EG/MXene@PP reaches 85.6 % under 1 sunlight, with an evaporation rate for light oil of 13.17 kg/m2/h, 8 times higher than natural volatilization. For crude oil floating on water, it achieves a 98 % oil removal efficiency in 6 h, with 41 wt% of the light fraction evaporated. This research provides distinctive insights into solar-driven oil spill remediation behavior and pioneers the SOEA strategy, offering rapid, efficient, and safe solutions for intricate oil spill scenarios.

Electrochemically fast preparation of superhydrophobic copper mesh for high-efficiency oil spill adsorption and oil-water separation

Oily wastewater and marine oil spills are a massive environmental and human threat. Conventional oil spill treatment methods include adsorption by absorbent materials, dispersants or adsorbents, and in situ burning. Superhydrophobic materials, as a material that can achieve oil-water separation, have great potential for application in oil spill treatment. Research on superhydrophobic oil spill treatment mainly focuses on materials such as sponges and fabrics. Although these materials can effectively perform oil-water separation or oil spill adsorption, they also have the disadvantages of complicated preparation methods and high costs. Here, we present a miniature device for oil-water separation and oil spill collection and recovery. The superhydrophobic copper mesh box can be used on its own as an oil-water separation device or in combination with a commercial polyurethane sponge as a miniature oil-absorbing device. The robust copper mesh is prepared in two steps: anodizing and impregnation. The superhydrophobic copper mesh had a high oil separation flux (32,330 L m−2 h−1) and efficiency (97%), which remained high (28,560 L m−2 h−1) and efficient (95%) after 20 cycles of separation. The combined micro oil adsorption device can adsorb different oils and fats on the water surface, and it has good reusability with oil adsorption capacity and efficiency up to 15.28 g/g and 98% and still has good oil adsorption capacity (11.54 g/g) and efficiency (94.6%) after 20 cycles of adsorption. Therefore, the prepared micro oil-absorbing device has promising application prospects in oil-water separation, oil spill cleanup, etc. Environmental ImplicationThis study demonstrates a facile electrochemical approach to prepare a miniature device for high-efficiency oil-water separation and oil spill collection and recovery. The modified copper mesh's separation flux could reach 32,330 L m−2 h−1, showing great promise in oil-water separation and oil spill cleanup.

Preparation and separation performance of biomimetic polycaprolactone/graphene oxide composite membrane

The treatment of oil and water pollutants generated in industrial production and daily life is an urgent issue that needs to be addressed globally. Inspired by superhydrophobic self-cleaning lotus leaves, durable and sturdy superhydrophobic water-filled barriers, and lightweight bird bones with hollow structures, researchers can obtain superhydrophobic surfaces by creating rough surfaces of layered micro- and nanostructures. In this study, hydrophobic polycaprolactone (PCL) membranes with layered structures were prepared by electrospinning. The surface roughness of the PCL membrane was improved by compounding graphene oxide (GO) functional components on the PCL membrane surface, thereby enhancing its hydrophobicity. The infrared spectrum of the PCL/GO membrane shows that PCL and GO are physically mixed, and no chemical changes occur during the electrospinning process. Scanning electron microscopy (SEM) images of the composite fibre membranes reveal the interconnections between fibres. Fourier transform infrared spectroscopy (FTIR) provides information on the chemical components of the membranes. Thermogravimetric analysis (TGA) was employed to assess the thermal stability of the membranes. The oil-water separation test demonstrated that the PCL/GO membrane exhibited a separation efficiency of 99.94% for hexane-water mixtures. In the oil adsorption test, the maximum adsorption capacity of the membrane for n-hexane was 35.8 g/g. In the contact angle measurement experiment, the water contact angle of the nanofiber membrane increased from 120.12° to 140.15° with increasing GO content, indicating that the composite membrane exhibited enhanced hydrophobicity.

Ultralight, shapeable, and superhydrophobic polyacrylonitrile/polybenzoxazine aerogel for high oil-water separation capacity

Environmental and human health are significantly threatened by oily wastewater emission and oil spills. Polymeric porous aerogels are ideal materials to absorb oils or organic solvents selectively, thereby mitigating environmental pollution and protecting human health. In this study, a shapeable, super-hydrophobic, polyacrylonitrile fiber/polybenzoxazine (PAN/PBOZ) aerogel with high oil-water separation ability were successful designed. The preparation process of PAN/PBOZ aerogel is as follows: Firstly, PAN micro-nanofibers were prepared by electrospinning, and then benzoxazine was uniformly dispersed into PAN fibers. After freeze-drying and thermal curing, the aerogel was obtained. For comparative analysis, a pure polyacrylonitrile (PAN) fiber aerogel is also presented. The resulting PAN/PBOZ aerogel exhibits ultralight (0.017 g/cm3), remarkable hydrophobicity, as evidenced by a water contact angle of 156°, high adsorption capacity up to 157.7 g/g for oil or organic solvents, and a high water-in-oil emulsion separation flux (9718 ± 45 L m−2 h−1) efficiently. Notably, the rigid cross-linking structure of PBOZ and the toughness structure of PAN make the aerogel exhibit synergistic strengthening and toughening effects. When the PAN/PBOZ fiber aerogel is compressed to 60 %, an outstanding recovery stability of its original size is displayed. While the springback of pure PAN fiber aerogel is poor under the same compression test condition. In conclusion, this study provides a preparation method and design concept of aerogel that can meet the requirements of low density, high toughness and high oil adsorption capacity. The rationally designed PAN/PBOZ aerogel shows significant potential for practical applications in treating oily and organic wastewater.

Laser‐assisted graphene‐like materials for oil‐spill clean up

AbstractConventional synthetic sorbents for oil spill cleanup are the most widely employed materials, although a major drawback is the extensive chemical modification that they have undergone, making them economically and environmentally nonsustainable. The use of inexpensive, abundant, nontoxic, biodegradable, and reusable lignocellulosic materials might be an alternative to conventional sorbents, with obvious positive impact on sustainability and circular economy. The present study subsequently utilizes the well‐established process, of converting grape molasses—a byproduct of the winemaking industry that represents a typical and abundant source of biomass—into a laser‐assisted graphene‐like product (LA‐B). Comparative experiments were carried out with two additional materials that are similarly produced by the same laser‐assisted method, yet use synthetic polyimide foil and tape polymers as precursors, namely LA‐F and LA‐T. The results showed that diesel oil adsorption capacity of LA‐B was 33.5 g/g, while the ultraoleophilic LA‐T adsorbed 57 g/g and LA‐F adsorbed 41 g/g. Furthermore, the crude oil uptake was 31.1, 56.0, and 38.6 g/g for LA‐B, LA‐T, and LA‐F, respectively. The adsorption of oil on the used materials could be well‐described by pseudo‐second‐order kinetics, showing that over 80% of oil was removed from the water within 15 min.

Experimental and Molecular Dynamics Simulation to Investigate Oil Adsorption and Detachment from Sandstone/Quartz Surface by Low-Salinity Surfactant Brines.

In this study, we explore the impact of monovalent (NaCl) and divalent (CaCl2) brines, coupled with sodium dodecyl sulfate (SDS) surfactant at varying low concentrations, on the detachment and displacement of oil from sandstone rock surfaces. Employing the sessile drop method and molecular dynamics simulations, we scrutinize the behavior of the brine solutions. Our findings reveal that both low salinity and low-salinity surfactant solutions induce a gradual shift in rock wettability toward a more water-wet state. This wettability transformation is not instantaneous but evolves over time, as observed through meticulous molecular motion analyses. Through contact angle measurements and molecular dynamics simulations, we delve into the molecular motion at subpore and micropore scales on sandstone/quartz surfaces. The adsorption of surface-active agents from the oil to the oil-brine interface results in a reduced interfacial tension, significantly contributing to oil displacement. Notably, low salinity concentrations ranging from 1000 to 10,000 ppm exhibit the lowest contact angles within 30 min across all solutions. However, higher concentrations deviate from this declining trend, especially with divalent ions like Ca2+, which bridge polar molecules onto the rock surface, resulting in an increased oil-wetting state. This research unveils the intricate molecular motions involved in employing low-salinity surfactant solutions for oil detachment from surfaces. Furthermore, it provides valuable insights into the underlying forces driving oil detachment and wettability alteration.

Adsorption of Oil from Industrial Wastewater with Eucalyptus globulus Labill. Bark: Optimization Study

Oily wastewater is one of the most hazardous contaminants that can hurt the ecosystem. There is an urgent need to adopt an efficient, eco-friendly, and low-cost material to replace the old traditional treatment methods of oily wastewater that were very expensive in addition to their relatively low efficiency. Eucalyptus bark is considered one of the materials that are rarely used in this field, although it has the characteristics that qualify it to be a distinguished and promising one. The optimum conditions of using Eucalyptus globulus Labill. (Blue gum) bark in the removal of oil from prepared aqueous solutions were concluded before applying in the treatment of real oily industrial wastewater from New Borg El-Arab City, Egypt. The sequential optimization adsorption results were as follows: initial oil concentration, 500 mg/l; adsorbent dosage, 0.5 g/l; pH, 3; exposure time, 45 min; temperature, 20 °C; and shaking rate, 300 rpm. The pretreatment of biomass with H3PO4 proved it to be superior in the oil removal process where the efficacy reached 450.69 mg/g, while the unmodified form came second where the adsorption efficacy reached 395.86 mg/g, after that the NaOH-modified form came third by efficacy reached 315.85 mg/g. The results of SEM elucidated this order of efficacy according to the porosity of the bark surface. FTIR analysis indicated that OH, carboxylic C = O, and carboxylic C-O groups are the contributing groups in the oil adsorption process for the three forms of Eucalyptus bark. The reusability of Eucalyptus bark using n-hexane for one cycle reached 96.34, 97.13, and 95.83% for unmodified, H-modified, and OH-modified forms, respectively, and for five cycles reached 56.29, 58.01, and 55.81% for unmodified, H-modified, and OH-modified forms, respectively. The application of Eucalyptus bark in the H-form in the treatment of real oily wastewater was achieved by efficacy ranging between 91.46 and 96.23% which proves the excellence of Eucalyptus bark in the treatment of oily wastewater.

Mechanisms of CO2-rich industrial waste gas enhanced shale oil recovery in kerogen slit based on adsorption behavior, gas flooding and surfactant synergy study

Enhanced oil recovery (EOR) by injection of CO2-rich industrial waste gas has been proposed as an energy-efficient and environmentally friendly method for shale oil reservoirs, in which the waste gas can be utilized and sequestered to reduce greenhouse gas emissions. In this work, the adsorption behaviors of shale oil and waste gas components in kerogen slits and the effects of gas flooding on EOR were investigated using molecular dynamics (MD) method, which can provide technical guide for shale oil development. In terms of the adsorption behaviors, an intensity decrease of oil adsorption is observed in kerogen slits after the injection of the waste gas components. Desorption of shale oil during injection of SO2 and CO2 is more pronounced in shallow reservoirs, whereas it is more evident for NO and N2 in deep reservoirs. The desorption efficiency can be 10.91 % for pure CO2 injection and 9.09 % for NO injection at a depth of 1000 m, and the relative stability ratios of CO2 and NO sequestration are 77.09 % and 76.06 %, respectively. For gas flooding, the existence of pressure difference provides favorable conditions for gas molecules to pass through the oil zone, and waste gas can be more effective than pure CO2 as driving gas. For the waste gas injection, the percentage of CO2 retained in the kerogen nanopores is much higher than that of pure CO2 injection, suggesting that more CO2 molecules can enter into kerogen matrix to take part in the displacement process. Furthermore, the effect of surfactants on oil desorption and displacement was also investigated and the interaction energy of the surfactant/oil/gas system was calculated and analyzed, finding that addition of the oil-soluble surfactants can be beneficial to shale oil displacement. This work can provide a comprehensive evaluation of the feasibility of CO2-rich industrial waste gas application for EOR, which is of great significance in the effective production of shale oil and the sequestration of waste gas in shale reservoirs.

Developing cellulose-based hydrophobic/hydrophilic composites for efficient adsorption of oils and heavy metals from water

The oily wastewater and heavy metal ions have been increasingly discharged into water environment, posting a serious threat to ecosystems and human health. However, it remains challenging to use single separation technology to effectively remove oil and heavy metal ions in oil-water mixtures simultaneously. Herein, novel hydrophobic/hydrophilic composites (HHC) were successfully prepared by using A4 paper-derived hydrophilic cellulose as the modified matrix, modifying the polydopamine layer and in-situ growth nanoscale zero-valent iron as active adsorption materials, combined with oleic acid-modified hydrophobic magnetic hollow carbon microspheres, which were used to efficiently and rapidly adsorb heavy metals and oil in oil-water mixtures. Under the optimal adsorption conditions, the adsorption amounts of As(III), As(V), Pb(II) and Cu(II) were 289.6 mg/g, 341.9 mg/g, 241.2 mg/g and 277.5 mg/g, respectively, and the mass transfer rate of HHC to the target ions is fast. The HHC have efficient separation performance for layered oil-water mixtures and emulsified oil-water mixtures, with separation efficiency of 97 % and 92 %. At the same time, due to the abundant adsorption sites, the HHC also exhibit splendid regeneration performance for the four ions after multiple adsorption utilization. Our work designed a approach to achieving promising oil and heavy metal adsorbents with higher adsorption capacity and better regenerative properties.