Application of Fe3O4 magnetite nanoparticles grafted in silica (SiO2) for oil recovery from oil in water emulsions

Sources, colloidal characteristics, and separation technologies for highly hazardous waste nanoemulsions

Nanoemulsions play a crucial role in various industries. However, their application often results in hazardous waste, posing significant risks to human health and the environment. Effective management and separation of waste nanoemulsions requires special attention and effort. This review provides a comprehensive understanding of waste nanoemulsions, covering their sources, characteristics, and suitable treatment technologies, intending to mitigate their environmental impact. This study examines the evolution of nanoemulsions from beneficial products to hazardous wastes, provides an overview of the production processes, fate, and hazards of waste nanoemulsions, and highlights the critical characteristics that affect their stability. The latest advancements in separating waste nanoemulsions for recovering oil and reusable water resources are also presented, providing a comprehensive comparison and evaluation of the current treatment techniques. This review addresses the significant challenges in nanoemulsion treatment, provides insights into future research directions, and offers valuable implications for the development of more effective strategies to mitigate the hazards associated with waste nanoemulsions.

Review on demulsification techniques for oil/water emulsion: Comparison of recyclable and irretrievable approaches

Since the establishment of the first global refinery in 1856, crude oil has remained one of the most lucrative natural resources worldwide. However, during the extraction process from reservoirs, crude oil gets contaminated with sediments, water, and other impurities. The presence of pressure, shear forces, and surface-active compounds in crude oil leads to the formation of unwanted oil/water emulsions. These emulsions can take the form of water-in-oil (W/O) emulsions, where water droplets disperse continuously in crude oil, or oil-in-water (O/W) emulsions, where crude oil droplets are suspended in water. To prevent the spread of water and inorganic salts, these emulsions need to be treated and eliminated. In existing literature, different demulsification procedures have shown varying outcomes in effectively treating oil/water emulsions. The observed discrepancies have been attributed to various factors such as temperature, salinity, pH, droplet size, and emulsifier concentrations. It is crucial to identify the most effective demulsification approach for oil/water separation while adhering to environmental regulations and minimizing costs for the petroleum sector. Therefore, this study aims to explore and review recent advancements in two popular demulsification techniques: chemical demulsification and magnetic nanoparticles-based (MNP) demulsification. The advantages and disadvantages of each technique are assessed, with the magnetic approach emerging as the most promising due to its desirable efficiency and compliance with environmental and economic concerns. The findings of this report are expected to have a significant impact on the overall process of separating oil and water, benefiting the oil and gas industry, as well as other relevant sectors in achieving the circular economy.

Highly effective synthesis of novel structured phospholipid emulsifiers using magnetically recyclable Fe3O4@SiO2/M (M = Zn or Al) composite

It is of great importance to develop a most efficient, recyclable, and ecofriendly process to produce novel structured phospholipid emulsifiers. Herein, innovative medium-chain structured phospholipid (MCSPL) emulsifiers were synthesized through transesterification of soybean lecithins with medium-chain fatty acids (MCFAs) promoted by Zn- or Al-incorporated Fe3O4@SiO2, denoted by Fe3O4@SiO2/M (M = Zn or Al). Resultingly, Fe3O4@SiO2/M (M = Zn or Al) exhibited the most superior reactivity with 97.1% or 88.7% MCFA incorporation to other benchmark catalysts and also had excellent magnetic separability and recyclability. Noticeably, targeted MCSPLs possessed almost more superior emulsifying properties to other phospholipid emulsifiers, and had potential for use as oil-in-water emulsifiers. Conclusively, the present findings demonstrate that transesterification promoted by Fe3O4@SiO2/M (M = Zn or Al) can be a promising approach for green, economic, and highly effective synthesis of novel dual-function phospholipid emulsifiers with bioactive and emulsifying properties in food, pharmaceutical, and cosmetic industries.

Research progress on the magnetite nanoparticles in the fields of water pollution control and detection

Magnetite nanoparticles (MNPs) have shown increasing application in the fields of water pollution control and detection due to their perfect combination of interfacial functionalities and physicochemical properties, such as surface interface adsorption, (synergistic) reduction, catalytic oxidation, and electrical chemistry. This review presents the research advances in the synthesis and modification methods of MNPs in recent years, systematically summarizes the performances of MNPs and their modified materials in terms of three technical systems, including single decontamination system, coupled reaction system, and electrochemical system. In addition, the progress of the key roles played by MNPs in adsorption, reduction, catalytic oxidative degradation and their coupling with zero-valent iron for the reduction of pollutants are described. Moreover, the application prospect of MNPs-based electrochemical working electrodes for detecting micro-pollutants in water were also discussed in detail. This review addresses that the construction of MNPs-based systems for water pollution control and detection should be adapted to the natures of the target pollutants in water. Finally, the following research directions of MNPs and their remaining challenges are outlooked. In general, this review will inspire MNPs researchers in different fields for effective control and detection of a variety of contaminants in water.

Optimization of water/oil emulsion preparation: Impact of time, speed, and homogenizer type on droplet size and dehydration efficiency

Due to their distinctive physical and chemical properties, emulsions are widely used in various industries such as pharmaceuticals, cosmetics, food, energy, and oil. Emulsion preparation differs from one application to another due to the effect of multiple parameters that can control droplet size and stability. However, there is a lack of fundamental understanding of the effect of emulsion preparation on its stability and performance. The emulsion preparation protocols can directly affect dehydration efficiency and stability. Herein, we report the influence of preparation conditions on the properties of the formed emulsions; we investigated the effect of mixing time, speed, and mixer type on the synthetic crude oil emulsion's droplet size and dehydration efficiency.

Adsorptive removal of Cr(III)-EDTA chelate from an aqueous solution by magnetic mesoporous silica microspheres

The 3-aminopropyltrimethoxysilane-modified magnetic mesoporous adsorbent (FNMs/APTES) was synthesized and applied to remove Cr(III)-EDTA chelates from water. The characterization of FNMs/APTES showed that the prepared adsorbent with a magnetic mesoporous structure was successfully grafted by APTES, which has good stability under acid conditions. The maximum capacities of FNMs/APTES for Cr(III)-EDTA adsorption at 15, 25 and 35 °C and pH 4.0 were 12.58, 13.13 and 14.00 mg·g^-1, respectively. The adsorption isotherm of FNMs/APTES for Cr(III)-EDTA conforms to the Freundlich model, and the adsorption kinetic model accords with the pseudo-second-order kinetic model. Adsorption of Cr(III)-EDTA on the adsorbent was not affected in the presence of Na⁺, K⁺ and Ca²⁺ even at 100 mmol·L^-1. Cr(III)-EDTA was anchored on FNMs/APTES through electrostatic interaction between protonated amino groups of adsorbents and Cr(III)-EDTA anions, and Cr(III)-EDTA chelates were adsorbed as a whole on the adsorbent. The Cr(III)-EDTA-saturated adsorbent can be readily regenerated in HCl solution and 83.03% of the initial Cr(III)-EDTA adsorption capacity remains after four adsorption-regeneration experiment cycles. The results highlighted that the FNMs/APTES as a potential adsorbent can be applied for the minimization of Cr(III)-EDTA chelates from water.

Exploring the characteristics, performance, and mechanisms of a magnetic-mediated washing fluid for the cleanup of oiled beach sand

In the present study, an innovative, environmentally benign recyclable, and magnetically mediated surface washing fluid based on water-dispersible magnetite nanoparticles has been designed and investigated for the cleanup of oiled beach sand. The characterization results showed that the as-prepared magnetite nanoparticles had a spherical morphology with an average diameter of around 250 nm and the particle surface was successfully functionalized with carboxyl groups. The magnetite nanoparticles could be easily re-dispersed by lightly shaking the dispersion after withdrawing the magnet. In addition, prolonging the magnetic field strength and response time promoted the oil recovery from the washing effluent. Thermodynamic modeling was applied to theoretically elucidate the mechanism and the results were in alignment with the experimental findings. Four mechanisms were identified to likely affect surface washing performance. The magnetic fluid had a relatively low operation cost and good reusability for a number of multiple cycles. In terms of other operational limitations, it was noted that washing performance declined as clay (kaolinite) concentrations and salinity values increased. Based on these findings, the proposed stable, low-cost magnetite fluid formulation warrants further investigation as the basis for an operational system for the cleanup of sand beaches contaminated by oil spills.

Rapid and efficient oil removal from O/W emulsions by hydrophobic porous polystyrene microspheres embedded with hydrophilic surface micro-regions

Inspired by Namib Desert beetle's back which is patterned with different wetting properties, hydrophobic porous polystyrene microspheres embedded with hydrophilic surface micro-regions (HPHs) were designed and fabricated by the radical copolymerization in the W₁/O/W₂ double Pickering emulsions with high internal water phase. The synergistic effect of the hydrophobic surface and the hydrophilic surface micro-regions results in HPHs exhibiting superior performances for separating both surfactant-free and surfactant-stabilized O/W emulsions. After 60 s hand-shaking, the oil was absorbed and stored within HPHs which could be separated from the water using a 600-mesh sieve, and the TOC values of purified water could be reduced to 2.06 ± 0.06-67.38 ± 2.02 ppm when the initial oil content was 1 vol%. Meanwhile, HPHs could be recovered and reused through a simple treatment. The excellent oil removal efficiency was kept even after 50 cycles. High oil removal efficiency, general applicability, easy operation and excellent recyclability endow HPHs with great potential for practical applications. And this work provides a facile and general way to prepare porous polymer microspheres with wettability contrast surfaces.

LAPONITE® nanodisk-"decorated" Fe3O4 nanoparticles: a biocompatible nano-hybrid with ultrafast magnetic hyperthermia and MRI contrast agent ability

Magnetic Fe₃O₄ nanoparticles "decorated" by LAPONITE® nanodisks have been materialized utilizing the Schikorr reaction following a facile approach and tested as mediators of heat for localized magnetic hyperthermia (MH) and as magnetic resonance imaging (MRI) agents. The synthetic protocol involves the interaction between two layered inorganic compounds, ferrous hydroxide, Fe(OH)₂, and the synthetic smectite LAPONITE® clay Na_0.7⁺[(Si₈Mg_5.5Li_0.3)O₂₀(OH)₄]_0.7^-, towards the formation of superparamagnetic Fe₃O₄ nanoparticles, which are well decorated by the diamagnetic clay nanodisks. The latter imparts high negative ζ-potential values (up to -34.1 mV) to the particles, which provide stability against flocculation and precipitation, resulting in stable water dispersions. The obtained LAPONITE®-"decorated" Fe₃O₄ nanohybrids were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), Mössbauer spectroscopy, dynamic light scattering (DLS) and vibrating sample magnetometry (VSM) at room temperature, revealing superior magnetic hyperthermia performance with specific absorption rate (SAR) values reaching 540 W g_Fe^-1 (28 kA m^-1, 150 kHz) for the hybrid material with a magnetic loading of 50 wt% Fe₃O₄/LAPONITE®. Toxicity studies were also performed with human glioblastoma (GBM) cells and human foreskin fibroblasts (HFF), which show negligible to no toxicity. Furthermore, T₂-weighted MR imaging of rodent brain shows that the LAPONITE®-"decorated" Fe₃O₄ nanohybrids predominantly affected the transverse T₂ relaxation time of tissue water, which resulted in a signal drop on the MRI T₂-weighted imaging, allowing for imaging of the magnetic nanoparticles.

Research on modified blast furnace dust in demulsification: The synergistic effect of ferric oxide, hydrophobic carbon, and polysilicate

Current treatment processes for the cold rolling emulsion wastewater were in the dilemma that the cost was so high while the efficiency was not satisfied in China. In this work, a novel material with high-performance demulsification was obtained and used to treat the emulsion wastewater efficiently by modifying blast furnace dust (BFD), a steel industry waste. Firstly, the BFD was characterized by various analytical techniques and the results suggested that hydrophobic functional groups, positively charged iron oxide, and polysilicon in the BFD were contributed to removing stable oil droplets. Therefore, the BFD modification was conducted accordingly by optimizing the proportion and reaction conditions of these three components. The study demonstrated that the removal rate of oil and COD_cr reached 75.21% and 81.23% under the conditions of the carbon type of GWF-HAC-R90, the carbon content of 14.86%, and the n_(Fe)/n_(Si) of 1.55, respectively. Based on this, the effects of pH, demulsifier dosage, and average agitation rate were investigated. The emulsion components before and after demulsification were analyzed by GC-MS, and the demulsification mechanism was expounded combined with kinetics. Results showed that the Fe₂O₃ with positive charge played a dominant role in emulsions with mainly anionic surfactants, while hydrophobic carbon structures and polysilicate acted as the auxiliaries. Besides, comprehensive analysis and characterization results suggested that the demulsification effect was a combination of the synergic processes: 1) electrostatic interaction developed by the anionic surfactant oil droplets and the positively charged the BFD particles; 2) hydrophobic association among the oil droplet with nonionic surfactant and amphiphilic carbon-iron complexes; 3) adsorption bridging between the surfactant oil droplets and polysilicate. The results of comparative tests in treating the actual cold-rolling emulsion wastewater showed the MBFD could bring about significant technical, economic benefits and achieve utilization of metallurgical solid wastes.Implications: Blast furnace dust (BFD) is an industrial solid waste obtained by dry de-dusting from blast furnace gas during the blast furnace ironmaking process. The main components of BFD are iron oxide and carbon, and also contain small amounts of different recoverable non-ferrous metals zinc, secret, indium and lead, which have recovery value. In this study, we enhanced the three parts of BFD and used to demulsification. In this study, the BFD was modified in three aspects (hydrophobic functional groups, positively charged iron oxide, and polysilicon) to achieve the secondary utilization of waste in emulsion wastewater treatment. And investigated the effect of reaction conditions on the demulsification effect with modified blast furnace dust (MBFD). Furthermore, the GC-MS analyzes combined with kinetics interpret the demulsification mechanism with the MBFD as a secondary resource. Finally, the comparative tests in treating the actual cold-rolling emulsion wastewater showed the MBFD could bring about significant technical and economic benefits and achieve utilization of metallurgical solid wastes.

High positively charged Fe3O4 nanocomposites for efficient and recyclable demulsification of hexadecane-water micro-emulsion

Oily wastewater not only causes major environmental issues, but also threatens human health. Magnetic nanoparticles (MNPs) are an attractively alternative commercial demulsifiers for their recyclability and high surface area. The wettability and surface charge of magnetic materials are significant factors in oily wastewater treatment. However, the specific influence of surface charge on the demulsification performance has not been rigorously investigated. Herein, a series of MNPs coated by dimethyl-diallyl-ammonium chloride (PDDA) and fulvic acid (FA) (Fe₃O₄/FA/PDDA) with different surface positive charges were synthesized by adjusting the PDDA concentrations and applied in demulsification of hexadecane-water micro-emulsion. The oil-water separation efficiency (Es) was enhanced gradually with increasing the surface positive charge of demulsifiers. Derjaguin-Landau-Verwey-Overbeek (DLVO) theory confirmed that with increasing surface positive potential, the electrostatic attraction between demulsifiers and oil droplets increased, and thus, Es increased. In addition, the superior Es of Fe₃O₄/FA MNPs for hexadecyl trimethyl ammonium bromide (CTAB)-stabilized micro-emulsions and Fe₃O₄/FA/PDDA MNPs for sodium dodecyl sulfate (SDS)-stabilized micro-emulsions further confirmed that electrostatic force was critical in demulsification. The high positively charged Fe₃O₄/FA/PDDA MNPs can be used as an efficient and recyclable demulsifier for hexadecane-water micro-emulsion. This study provides a theoretical basis for designing demulsifiers.

A critical review of the development and demulsification processes applied for oil recovery from oil in water emulsions

The formation of stable emulsions is a fundamental problem in oil industry that can result in a sequence of environmental and operational problems. Chemical demulsification is extensively applied for the recovery of oil from water as well as water from oil. This review introduces different chemical demulsifiers applied for the demulsification and recovery of oil from oil in water (O/W) emulsions. Main types of surfactants (anionic, cationic, nonionics and amphoteric) involved in the formation of emulsions and enhances their stability were discussed. Promising demulsifiers such as nanoparticle (NP), hyperbranched polymers, and ionic liquids (IL), which achieved high oil recovery rate, parameters influencing demulsification efficiency and demulsification mechanisms were explored. Lastly, improvements, challenges, and new changes being made to chemical demulsifiers were underlined. Functionalized magnetic nanoparticles and hyperbranched polymers were very effective in recovering oil from O/W emulsions with an efficiency >95%. Polymers with highly hydrophilic content and high molecular weight can achieve excellent oil recovery rates due to higher interfacial activity, higher dispersion, and presence of specific functional groups. Although ionic liquids could achieve oil recovery up to 90%, high cost limits their applications. NPs showed excellent oil recovery behavior at low concentrations and ambient temperature. Demulsification efficiency of NPs can be enhanced by functionalize with other components (e.g., polymers and surfactants), while service life can be extend by silica coating. Future challenges include scaling up the use of NPs in oil recovery process and highlighting contrasts between lab-scale and field-scale applications.

Recyclable amine-functionalized carbon nanotubes for the separation of oily wastewater

In this work, a CNTs-NH₂ demulsifier was prepared by grafting ethylenediamine on the surface of carbon nanotubes to break oily wastewater. The physicochemical and interfacial properties of CNTs-NH₂ were characterized and analyzed. It showed that CNTs-NH₂ had an eminent amphipathicity and high interfacial activity, which allows it to sharply migrates to the interface and effectively interacts with interfacial film by the combined action of π-π interaction and electrostatic attraction. The demulsification tests exhibited that CNTs-NH₂ could effectively remove emulsified oil from the oily wastewater. It could be used at acidic and neutral conditions, and high salinity. Moreover, it could be recycled and still maintained its interfacial activity, thusly vastly enhancing the application scope. The light transmittance was up to 88.1% and the corresponding oil removal rate was 99.2% with 100 mg/L of CNTs-NH₂ for 30 min. The oil removal rate of CNTs-NH₂ remained above 97.8% after 6 cycles. This work provides a deep understanding on the design of demulsifier and its demulsification mechanism.

Magnetic γ-Fe2O3/ZIF-7 Composite Particles and Their Application for Oily Water Treatment

Crude oil spills are about global challenges because of their destructive effects on aquatic life and the environment. The conventional technologies for cleaning crude oil spills need to study the selective separation of pollutants. The combination of magnetic materials and porous structures has been of considerable interest in separation studies. Here, γ-Fe₂O₃/ZIF-7 structures were prepared by growing a ZIF-7 layer onto supermagnetic γ-Fe₂O₃ nanoparticles with an average size of 18 ± 0.9 nm in situ without surface modification at low temperatures. The product composite particles were characterized using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, vibrating sample magnetometry, and N₂ adsorption/desorption isotherms. The analyses revealed a time growth-dependent ZIF-7 rod thickness with abundant nanocavities. The γ-Fe₂O₃/ZIF-7 surface area available for sorption (647 m²/g) is ∼12-fold higher than that of the γ-Fe₂O₃ nanoparticles. Moreover, the crystal structure of γ-Fe₂O₃ remained essentially unchanged following ZIF-7 coating, whereas the superparamagnetism declined depending on the coating time. The γ-Fe₂O₃/ZIF-7 particles were highly hydrophobic and selectively and rapidly (<5 min) sorbed crude oil and other hydrocarbon pollutants from water. As high as 6 g/g of the hydrocarbon was sorbed by the γ-Fe₂O₃/ZIF-7 particles immersed into the hydrocarbon. A coefficient of determination, R ₂ ², consistently >0.96 at all pollutant concentrations suggested a pseudo-second-order sorption kinetics. The thermal stability and 15 cycles of use and reuse confirmed a robust γ-Fe₂O₃/ZIF-7 sorbent.

Demulsification of water-in-crude oil emulsion driven by a carbonaceous demulsifier from natural rice husks

Removing emulsified water from a water-in-crude oil (W/O) emulsion is critically required prior to downstream processing in the petroleum industry. In this work, environmentally friendly and amphipathic rice husk carbon (RHC) demulsifier was prepared by a simple carbonization process in a muffle furnace using rice husks as starting materials. RHC was characterized by field-emission scanning electron microscope, energy dispersive spectrometer, Fourier transform infrared spectrometer, ultraviolet-visible spectrometer, powder X-ray diffraction, zeta potential and synchronal thermal analyzer. The factors such as dosage, temperature, settling time, pH value and salinity were systematically investigated. The results indicated that the dehydration efficiency (DE) reached as high as 96.99% with 600 mg/L of RHC for 80 min at 70 °C. RHC exhibited an optimal DE under neutral condition, but it was also effective under acidic and alkaline conditions. Also, it had an excellent salt tolerance. The possible demulsification mechanism was explored by interfacial properties, different treatment methods for RHC and microexamination. The demulsification of RHC is attributed to its high interfacial activity, oxygen-containing groups and content of silica. It indicates that RHC is an effective demulsifier for the treatment of the W/O emulsion.

Mechanistic Insights into the Thermal Decomposition of Ammonium Perchlorate: The Role of Amino-Functionalized Magnetic Nanoparticles

This work reports the characterization and application of two promising nanocatalysts for the thermal decomposition of ammonium perchlorate (AP). To obtain these composite materials, magnetite nanoparticles (Fe₃O₄ NP_s) were functionalized with two different amine derivative groups, tertiary amine (Fe₃O₄ NP_s-A1) and quaternary amine. X-ray photoelectron spectroscopy and differential scanning calorimetry provided mechanistic insights into the thermal decomposition of AP. Furthermore, tertiary and quaternary amine groups play a critical role, where the presence of an extra proton could favor an electron-proton transfer as the rate-determining step. Moreover, Fe₃O₄ NP_s-A1 causes a diminution of the high-temperature decomposition of AP positively to 335 °C, increasing the energy release by 278 J g^-1 and consequently affording the lowest activation energy (102 kJ mol^-1), indicating a low degree of thermal stability, and accelerating the thermal decomposition of AP.

Polyethylene over magnetite-multiwalled carbon nanotubes for kerosene removal from water

In this study, a nano-adsorbent was prepared for kerosene removal from water. Multiwalled carbon nanotubes (MWCNTs) were functionalized with concentrated HNO₃ (nitric acid). Subsequently, Fe₃O₄ (magnetite) nanoparticles were deposited on the MWCNTs to prepare a magnetite/MWCNTs (Fe-MWCNTs) nanocomposite. Then, polyethylene was added to the Fe-MWCNTs to fabricate a polyethylene/magnetite/MWCNTs (PE/Fe-MWCNTs) novel nanocomposite. The nano-adsorbent was characterized using BET, FTIR, Raman, XRD, TEM, and SEM. A kerosene-water model mixture was used for adsorption tests. Several parameters: adsorption time, adsorbent dose, solution pH, solution temperature, and kerosene concentration in the kerosene-water model mixture, were analyzed during adsorption experiments. After each batch experiment, kerosene concentration was determined using high-performance liquid chromatography (HPLC). Magnetic field was used to remove the adsorbent after each experiment. The kerosene adsorption capacity and removal efficiency of the PE/Fe-MWCNTs nanocomposite (3560 mg/g and 71.2 %, respectively) were higher than those of Fe-MWCNTs, ox-MWCNTs, and fresh MWCNTs (3154 mg/g and 63.1 %, 2204 mg/g and 44.0 %, and 2092 mg/g and 41.8 %, respectively). Kerosene adsorption followed a pseudo-second-order kinetic model (R² = 0.999) and the Langmuir isotherm model, suggesting that adsorption was uniform and homogenous process.

Design of Magnetic Hydrogels for Hyperthermia and Drug Delivery

Hydrogels are spatially organized hydrophilic polymeric systems that exhibit unique features in hydrated conditions. Among the hydrogel family, composite hydrogels are a special class that are defined as filler-containing systems with some tailor-made properties. The composite hydrogel family includes magnetic-nanoparticle-integrated hydrogels. Magnetic hydrogels (MHGs) show magneto-responsiveness, which is observed when they are placed in a magnetic field (static or oscillating). Because of their tunable porosity and internal morphology they can be used in several biomedical applications, especially diffusion-related smart devices. External stimuli may influence physical and chemical changes in these hydrogels, particularly in terms of volume and shape morphing. One of the most significant external stimuli for hydrogels is a magnetic field. This review embraces a brief overview of the fabrication of MHGs and two of their usages in the biomedical area: drug delivery and hyperthermia-based anti-cancer activity. As for the saturation magnetization imposed on composite MHGs, they are easily heated in the presence of an alternating magnetic field and the temperature increment is dependent on the magnetic nanoparticle concentration and exposure time. Herein, we also discuss the mode of different therapies based on non-contact hyperthermia heating.

Enhanced oil recovery using hyperbranched polyglycerol polymer-coated silica nanoparticles

Functionalized Fe₃O₄-SiO₂ magnetic nanoparticles (Fe-Si-MNPs) coated with hyperbranched polyglycerol polymer were prepared and tested for oil recovery from oil in water (O/W) emulsions. The structure, chemistry, and surface modifications of the newly developed demulsifier (PSiMNPs) were analyzed, and the percentage demulsification efficiency (%η_dem) was tested at differing concentrations of surfactant (C_sur), oil (C_oil), and demulsifier (D_PSiMNPs). The developed PSiMNPs can be separated from the solution by a magnetic field, regenerated using ethanol, and reused several times. The reported %η_dem was ≥80% for all the studied C_oil. The %η_dem improved as the C_sur and pH decreased, with maximum values of 98.8% and 98.5% achieved at C_sur = 0.05 g/L and a pH = 4, respectively. A D_PSiMNPs = 100 mg/L was sufficient to achieve %η_dem of 99.4% for C_oil = 100 mg/L and slightly decreased to ~93% for C_oil ~4000 mg/L. The PSiMNPs can be reused up to 15 times with a steady %η_dem of 89.1% for C_oil = 100 mg/L and 88.6% for C_oil = 4000 mg/L. The adsorption of oil on the PSiMNPs follows Freundlich isotherm with maximum adsorption capacity (q_max) of 192.8 g/mg and Langmuir constant (b) of 28.06 mg/L for C_oil = 900 mg/L. The q_max of the recycled PSiMNPs slightly decreased to 189.08 g/mg. The kinetic of oil recovery follows the PSO with a K₂ of 0.0169 g/mg. min. Surface modification of Fe-Si-MNPs enhanced the oil adsorption, increased the adsorption capacity, and extended the service life resulting in a better cost and process feasibility.

Computer-Aided Modeling, Simulation, and Exergy Analysis of Large-Scale Production of Magnetite (Fe3O4) Nanoparticles via Coprecipitation

Magnetite nanoparticles present attractive properties including high magnetization, low toxicity, adsorption capacity, and simple preparation, making them efficient in water purification processes, soil remediation, and biomedical applications. In this sense, there is growing interest in the production of magnetite nanoparticles; therefore, evaluating the performance of this process on a large scale gives relevant information to process designers. In this work, the simulation and exergy analysis of large-scale production of magnetite nanoparticles via coprecipitation were performed using computer-aided tools. The process was modeled for the production of 807 t/year of magnetite nanoparticles; the data for the simulation were obtained from the literature, and experimental results were developed by the authors. The exergy efficiency of the process was estimated at 0.046%. The exergy of waste was estimated to be 105 313 MJ/h, while the unavoidable exergy losses were 2941 MJ/h. Washing 2 and 3 represented the most critical stages of the process, contributing 95.12% of the total irreversibilities due to the waste exergy, which corresponds to the water and ethanol exergy discarded in these stages. These results show that the process must be improved from the energy point of view and require the implementation of process optimization strategies to reach a more sustainable design.

A new insight into the separation of oil from oil/water emulsion by Fe3O4-SiO2 nanoparticles

Nanofluids have shown their potential in the oil recovery process through surface modification. Due to their surface characteristics, they can apply to improve the oil production from reservoirs by enabling different enhanced recovery mechanisms. The preparation and development of the Fe₃O₄@SiO₂ nanoparticles for the oil recovery process is an innovative and novel approach that influences the oil generation from reservoirs. The performance of the Fe₃O₄@SiO₂ and the other nanofluids (seawater, Fe₃O₄, and SiO₂) in the enhanced oil recovery process is assessed and compared with other flooding scenarios. The Fe₃O₄@SiO₂ NPs achieved the highest oil production rate of 90.2% while Fe₃O₄ and SiO₂ NPs achieved 70.8% and 55.3%, respectively. In contrast, the value achieved for the seawater injection was 76.5%. For the oil recovery process, the Fe₃O₄ was applied for the inhibition (i.e., decrease) of oil sedimentation, and the SiO₂ NPs were applied for wettability alteration and IFT reduction. The experimental results showed that the produced Fe₃O₄@SiO₂ NPs improved the oil recovery rates (90.2%) as well as the synergetic impact of the developed NPs by initiating several mechanisms corresponding to the use of the separate NPs in the micromodel. Moreover, the results exhibited that the reservoir conditions are a crucial function for increasing the oil recovery rates, improving the emulsion stability, and acts as a substantial step for the oil recovery method that applies this particular technique.

Functionalization of silica-coated magnetic nanoparticles as powerful demulsifier to recover oil from oil-in-water emulsion

This study presents an innovative approach for the preparation of Fe₃O₄ nanoparticles covered with SiO₂ shell (denoted as Fe-Si-MNP), which were used to recover oil recovery from oil-in-water emulsion (O/W-emul). The Fe-Si-MNP were prepared with differing silica layer thicknesses (5 nm [Fe-Si-1], 8 nm [Fe-Si-2], 10 nm [Fe-Si-3], and 15 nm [Fe-Si-4]) and tested for the percentage of oil separation (%S_oil) under different dosages (D_MNP), oil concentration (D_oil), surfactant dosages (D_sur), and pH. The Fe-Si-MNP exhibited excellent %S_oil, reliable stability, and high magnetization values ranging between 46.1 and 80.2 emu/g. adding a 5 nm silica layer on the surface of the Fe-Si-MNP (i.e., Fe-Si-1) protected them from oxidation conditions, extended their service life, and achieved a %S_oil of ∼96.3%. The %S_oil slightly decreased to ∼92% with an alkaline pH or when the thickness of the silica layer increased to ≥10 nm. The %S_oil was 90.5%, 89.5%, and 87.5% for Fe-Si-2, Fe-Si-3, and Fe-Si-4, respectively. Increasing the water salinity from 0.1 to 0.5 M slightly improved the %S_oil for the tests carried out with a D_oil of 100 mg/L to 93.3%, 90.3%, and 86.3% for Fe-Si-2, Fe-Si-3, and FeSi-4, respectively. The highest %S_oil achieved with Fe- Si-1 Fe-Si-2 and Fe-Si-3 was >95%, 95% and 92%, respectively. The Fe-Si-MNP exhibited a high recyclability for 9 cycles with the lowest %S_oil ∼80%. The results suggest that the structure and properties of the Fe-Si-MNP can be manipulated to achieve a high oil recovery, easy separation, and extended service life.