Oily Particles Research Articles

Natural filter: Adjustable hydrophobicity from biodegradable zein nanofiber membrane for high efficiency air purification

Faced with the fact that air filtration materials prepared from traditional petroleum-based materials do not have good biodegradability and have the risk of causing secondary pollution to the environment, a kind of nanofiber membrane with biodegradable polylactic acid (PLA) and zein was prepared by electrospinning method. The morphology of as-prepared membrane was carried out along with filtration performance and degradation performance both experimentally and theoretically. The results showed that the hydrophobicity of nanofiber membrane can be adjusted by changing the ratio of PLA and zein. In addition, the highest filtration efficiency for PM2.5 and PM10 was achieved when the ratio of PLA to zein was 1:1, and it could be stabilized at 98.14 % and 97.39 %, and had the highest quality factor (QF) of 0.00738 Pa−1. Moreover, the fiber membrane has excellent adsorption effect on aqueous particles as well as oily particles. Notably, the as-prepared composite filter can be easily biodegraded thus contributing to green ecological environment.

Fluorine-Free Amphiphobic SBS/PAN Micro/Nanofiber Membrane by Integrating Click Reaction with Electrospinning for Efficient and Recyclable Air Filtration.

The membrane fouling derived from the accumulated dust pollutants and highly viscous oily particles causes irreversible damage to the filtration performance of air filters and results in a significant reduction in their service life. However, it is still challenging to construct high-efficiency and antifouling air filtration membranes with recyclable regeneration. Herein, the fluorine-free amphiphobic micro/nanofiber composite membrane was controllably constructed by integrating click chemistry reaction and electrospinning technique. Low-surface-energy fibers were constructed by a thiol-ene click chemical reaction between mercaptosilane and vinyl groups of polystyrene-butadiene-styrene (SBS), combined with hydroxyl-terminated poly(dimethylsiloxane) during the electrospinning process. The functional air filter is then prepared by the two-layer composite strategy. Because of the advantages of liquid-like fibrous surface and micro/nanofibrous porous structure, SBS/PAN composite membrane simultaneously shows superior antifouling performances of pollutants and filtration efficiency of over 97% PM0.3 removal. More importantly, the antifouling fibrous membrane still presents a stable and efficient filtration efficiency after multiple washes. Its service life in dust filtration environments is approximately 1.7 times longer than that of the substrate membrane. This work may provide a significant reference for the design of antifouling fiber membranes and high-efficiency air filters with long life spans and reusability.

Study on condensation of oily particles under the influence of water vapor phase transition

To address the problem that oily fine particles are too small to be easily captured by traditional dust removal equipment, which hinders improving the purification efficiency, this paper proposes using the technical principle of water vapor phase transition to conduct experiments and simulations. A set of water vapor experimental devices for fine particles of oil mist is designed, and the data are analyzed by a Grimm spectrometer. The experimental results show the phase change of water vapor has a remarkable effect on the agglomeration of oily fine particles. Phase change condensation makes the particle size of fine particles increase by 5–10 times in a truly brief time, and the polymerization and removal efficiency are greatly improved. To analyze the changes of the coalescence characteristics in a larger range of parameter changes, the Euler multiphase flow model is adopted, the particle condensation growth rate function is introduced by a user-defined function to establish a coalescence model and the heterogeneous condensation growth characteristics of oily particles are analyzed in a supersaturated water vapor environment. The simulation results show that the condensing chamber temperature of the condensing chamber is 283 K, and the lower the air flow rate of the condensing chamber, the more favorable the heterogeneous condensation growth of oil particles. The change rule of agglomeration characteristics of oily particles obtained by experiment and simulation proves the feasibility of improving the removal efficiency of oily fine particles.

Flow resistance and particle separation efficiency of a rectangular-spoke rotating disk: Influence of spoke configuration and number

How to effectively separate oily particles before they enter exhaust ducts and thus reduce their accumulation has always been a challenge. This paper proposed a general rotating disk with three different spoke configurations, namely, straight spoke (SS), backward-curved spoke (BCS), forward-curved spoke (FCS), and compared their airflow characteristics and capture performance in a specified exhaust duct. Affected by the divergence effect, the BCS disk has the highest flow resistance (ΔP) and lowest separation efficiency, while the FCS disk has the lowest ΔP and highest efficiency due to the convergence effect. Subsequently, two refining methods were applied to the disks with the three spoke configurations to improve the particle separation efficiency. The FCS disk consistently maintains the highest separation efficiency (ηp), e.g., 0.83 and 0.70 for 5 μm particles at 3000 rpm under equal refining and gradient refining methods, respectively. When being refined equally, the quality factor (QF) of the FCS disk increases with the rotating speed, reaching 0.038 Pa−1 at 3000 rpm, almost equivalent to the initial QF of the fiber filter and spacer fabric, significantly higher than that of the SS disk (0.026 Pa−1) and the BCS disk (0.024 Pa−1). When gradient refining is used, however, the maximum QFs of SS, BCS, and FCS disks appear at 2200, 1800, and 2600 rpm, respectively, thus making the gradient refining method economical only at a lower rotating speed. Finally, on the base of the area under curve index and the straight linear cluster method, the applicability of disks with different spoke configurations in a residential kitchen, which is a typical scenario for collecting oily particles in civilian buildings, was evaluated. Gradient-refined SS disk, equal-refined FCS disk, and equal-refined SS disk can meet the requirements of maximum exhaust attenuation. The gradient-refined SS disk and equal-refined FCS disk have the highest quality, with ηp reaching 0.61 and 0.48, respectively. The findings can provide solid support for the design of rotating disks to separate oily particles, especially in residential kitchens.

Stearate and hindered amine light stabilizers coordinate to boost charge storage performance of water electret melt-blown nonwovens

Water electret (WE) technology is a current research hotspot in the field of high-efficiency and low-resistance melt-blown filter materials. The electret is an important factor affecting the filtration performance and durability of WE melt-blown nonwovens. In this paper, WE melt-blown nonwovens were prepared with stearate compounded with hindered amine light stabilizer (HALS) as the electret additives, which exhibited excellent performance and the filtering efficiency of DEHS oily particles exceeding 99%. The charge formation and storage mechanism of WE melt-blown nonwoven were also elucidated by using the thermally stimulated discharge technique. Benefiting from the inherent amino group of HALS and the synergistic effect with stearate, positively charged hydrated protons were attracted and migrated to the interior of the fiber to form durable space charges, which led to a significant enhancement of the filtration/charge storage performance of melt-blown nonwoven. The charge stability performance of WE melt-blown nonwoven was also investigated under the treatment of solvents such as constant temperature and humidity, high-temperature hot water, alcohol, and isopropyl alcohol. These studies help to improve the product quality of WE melt-blown nonwovens, as well as provide a systematic guide to an in-depth understanding of the electret mechanism of WE technology.

Development and evaluation of a triangular prism-multiple tubular wet electrostatic precipitator for capturing moxibustion oil fumes

Moxibustion oil fumes (MOF) have caused serious indoor air pollution. To solve the high costs problem existing in the current air purification technology, a triangular prism-multiple tubular wet electrostatic precipitator (WESP) was developed. The discharge characteristics of the modified WESP and the factors affecting its fractional collection efficiency (FCE) were explored in detail, and the collection performance of the modified WESP was further characterized by laboratory-scale tests. The results showed that the flushing water not only effectively cleaned the collection electrodes but also enhanced the corona current. Although increasing the applied voltage and reducing the flue gas velocity can improve the FCE, it was necessary to ensure that the ozone concentration met the emission standards. Specifically, the FCE of the modified WESP reached 43.09 %-97.48 % when the applied voltage was 15.5 kV, the flue gas velocity was 0.9 m·s−1, and the water consumption was 7.93 L· min−1·m−2. Under the optimal operation parameters, the modified WESP had an extremely low pressure drop (23 Pa) and a high clean air delivery rate (43.38 m3·h−1). After 12-h of continuous operation, the FCE of the modified WESP decreased slightly, but the FCE can be effectively recovered by cleaning the discharge electrodes. In conclusion, the modified WESP had the potential to efficiently capture MOF at low cost. Furthermore, the characteristic of MOF particles charged by the combustion process also helped us understand the high FCE of the modified WESP for MOF. Moreover, a modified efficiency equation of the triangular prism-multiple tubular WESP was proposed, and the experimental data were in good agreement with theoretical values. In addition, the modified WESP can provide a viable technical pathway to control oily particles emission.

Electrospun Ag‐dopedPA6multi‐stage structured nanofiber membrane with antibacterial property for oily particulate matters filtration

AbstractOily particulate matter pollution and bacteria pose a serious threat to human health and have drawn widespread attention. Herein, an Ag‐doped nylon 6 multi‐stage structured antibacterial nanofiber membrane (PA6&Ag MSNM) for effective air filtration of fine oily particulate matters was fabricated by adding a certain amount of tetrabutylammonium hexafluorophosphate (TBAHP) and silver nitrate (AgNO3) into PA6 solution via one‐step electrospinning. The fabricated PA6&Ag MSNM is composed of coarse trunk fibers and fine branching fibers, which exhibits high filtration efficiency for oily particulate matters and low pressure drop, with an average filtration efficiency of 99.92% for oily particles of 0.20 ~ 4.59 μm and a low pressure drop of 386 Pa. In addition, the fiber membranes possesses excellent antibacterial properties due to the doping of Ag. The prepared multi‐stage electrospun nanofiber membrane may provide a versatile strategy for designing new antibacterial air filtration materials, which would have broad application prospects.

Experimental Study on the Agglomeration of Oily Fine Particles by Sound Wave

Oily fine particles are an important air pollutant in industrial environments. Workers exposed to oil mist for a long time face great health risks. Particle growth pretreatment is a technical principle to increase particle size and improve purification efficiency. Acoustic waves are commonly used to acheive particle growth, and a large number of acoustic wave agglomeration experiments have been carried out on non-oil fog. However, studies on oily particles are few. On the basis of previous studies on acoustic agglomeration of non-oily particles, this experiment designed a set of experimental equipment to compare the agglomeration effect of oily and non-oily particles. It was found that the agglomeration effect ratio of oily and non-oily particles to φ1oiliness/φ1non-oily particles was greater than 1. Therefore, the agglomeration effect of oily particles under stationary acoustic waves was more obvious. Results clearly show that oily particles have a higher agglomeration ability. In this study, a traditional ventilation and purification technology was expanded to include sound agglomeration technology into the pretreatment stage of purification and dust removal, thereby demonstrating feasibility of improved purification efficiency of an oily fine particle purification system, and laying a foundation for engineering applications.

Electrospun PA6 multi-stage structured nanofiber membrane with high filtration performance for oily particles

ABSTRACT Oily particles pollution poses a tremendous threat to people’s health, so it is urgent to develop air filtration materials with the ability of removing fine oily particles effectively. In this study, a nylon 6 multi-stage structured nanofiber membrane (PA6 MSNM) for effective air filtration of fine oily particles was designed and fabricated by adding a certain amount of tetrabutylammonium hexafluorophosphate (TBAHP) via one-step electrospinning. The PA6 MSNMs were composed of coarse trunk fibres and fine branching fibres. Benefiting from the properties of small pore size and high porosity, the resulting PA6 MSNMs exhibited high average filtration efficiency of 99.80% for oily aerosol particles of 0.20–4.59 μm, a low pressure drop of 251 Pa, and the high quality factor of 0.0248 Pa−1. More importantly, its filtration efficiencies for oily aerosol particles of 0.25 and 0.30 μm were up to 99.99% and 100.00%, respectively. It is expected that the multi-stage electrospun nanofiber membranes would have wide application prospects in air filtration, particularly for filtering oily particles.

Zr doped flexible TiO2 nanofibrous membranes for high-efficiency oily particulate matter removal from high temperature flue gas

The filtration of high-temperature flue gases containing complex gas composition and oily particulate matter (PM) poses great challenges to the design of air filtration membranes. Ceramic nanofibers are potential membrane materials that possess the thermal resistance necessary for high-temperature filtration but the inherit poor brittleness limits their use. Herein, we report the fabrication of a flexible and porous Zr-doped TiO2 nanofibrous membrane (Zr–TiO2 NFM) for oily PM removal from high-temperature flue gas. The doping of Zr4+ ions not only improved the mechanical strength, leading to an outstanding tensile strength as high as 1.78 MPa, but also endowed a high specific area (68.34 m2 g−1). The prepared Zr–TiO2 NFMs possessed a high filtration efficiency of 99.98% with low pressure drop of 96 Pa (industrial gas velocity of 1 m∙min−1) and excellent long-term stability after 5 cycles of filtration at 350 °C. Significantly, different capture and evolution behaviors of PM at 25–350 °C were discovered. Below 200 °C, the oily particles would adhere, coalesce, spread out and form oil film on fibers. Different from oily particles, the non-oily particles would attach and accumulate on the fibers when temperatures are higher than 200 °C. This study brings a new insight to deeply understanding the capture process of PM at different temperatures and designing next-generation membranes for high temperature flue gas filtration.

Effects of Different Concentrations of Oil Mist Particulate Matter on Pulmonary Fibrosis In Vivo and In Vitro.

Oil-mist particulate matter (OMPM) refers to oily particles with a small aerodynamic equivalent diameter in ambient air. Since the pathogenesis of pulmonary fibrosis (PF) has not been fully elucidated, this study aims to explore the potential molecular mechanisms of the adverse effects of exposure to OMPM at different concentrations in vivo and in vitro on PF. In this study, rats and cell lines were treated with different concentrations of OMPM in vivo and in vitro. Sirius Red staining analysis shows that OMPM exposure could cause pulmonary lesions and fibrosis symptoms. The expression of TGF-β1, α-SMA, and collagen I was increased in the lung tissue of rats. The activities of MMP2 and TIMP1 were unbalanced, and increased N-Cadherin and decreased E-Cadherin upon OMPM exposure in a dose-dependent manner. In addition, OMPM exposure could activate the TGF-β1/Smad3 and TGF-β1/MAPK p38 signaling pathways, and the differentiation of human lung fibroblast HFL-1 cells. Therefore, OMPM exposure could induce PF by targeting the lung epithelium and fibroblasts, and activating the TGF-β1/Smad3 and TGF-β1/MAPK p38 signaling pathways.

The Fabrication of Oleophobic Coating and Its Application in Particulates Filtration

The stir-frying process in Chinese cooking has produced serious emissions of oily particles, which are an important source of urban air pollution. In particular, the complex composition of fine particulate may pose a threat to human respiratory and immune systems. However, current filtration methods for oily particulate fumes have low filtration efficiency, high resistance, and high equipment costs. In polypropylene (PP) electret filters, efficiency rapidly decreases and pressure drop (wind resistance) sharply increases after the adsorption of oily particles, due to the oleophilic properties of the PP fibre. We addressed this issue of filter performance degradation by fabricating a sodium perfluorooctanoate (SPFO) oleophobic coating on polyvinylidene fluoride (PVDF) fibre membranes for oily particle filtration. The SPFO coating showed a promising oleophobic effect even at low concentrations, which suggests it has oleophobic properties for different oil types and can be modified for different substrates. This fabricated oleophobic coating is thermostable and the oleophobic effect is unaffected by temperatures from 0 to 100 °C. By modifying the SPFO coating on the PVDF membrane, a high filtration efficiency (89.43%) and low wind resistance (69 Pa) was achieved without oil adhesion, so the proposed coating can be applied in the filtration and purification of oily fine particles and offers a potential strategy for preventing atmospheric oil pollution.

Design of Sodium Alginate/Gelatin-Based Emulsion Film Fused with Polylactide Microparticles Charged with Plant Extract.

This study aimed at designing emulsion films based on sodium alginate, gelatin, and glycerol, and their modification by the addition of lipids (cottonseed oil and beeswax). Film composition with the most promising properties was further modified by the incorporation of polylactide (PLA) microparticles with Calendula officinalis flower extract. PLA microspheres were obtained by the emulsion/solvent evaporation method. The size distribution of oily particles in emulsions was investigated. Mechanical properties, moisture content, UV-Vis spectra, and the color of films were analyzed, while biophysical skin parameters were assessed after their application to the skin. Moreover, the contact angles were measured, and the surface free energy of polymeric films was determined. An investigation of the amount of Calendula officinalis flower extract which can be incorporated into PLA microparticles was performed. The modification of the composition of films significantly influenced their physicochemical properties. The selected active ingredient in the form of plant extract was successfully incorporated into polymeric microparticles that were further added into the developed emulsion film. The condition of the skin after the application of obtained emulsion films improved. The prepared materials, especially containing microparticles with plant extract, can be considered for designing new cosmetic forms, such as cosmetic masks, as well as new topical formulations for pharmaceutical delivery.

Charged graphene aerogel filter enabled superior particulate matter removal efficiency in harsh environment

Fine particles pose a dangerous threat to our environment and human health. Although a series of air filters have been developed, to achieve high removal efficiency while maintaining a low pressure drop is still a challenging task. Herein, we introduce an additional force into action – the space charge when designing the filter to capture the particulate matters (PMs). The corona discharge drives the PMs toward graphene aerogel filter under the imposed electrostatic force. The prepared filter displays a very high PM removal efficiency and low pressure drop under an extremely high concentration (>10000 μg/m3) of both non-oily particles (>99.9%) and oily particles (>99.6%). In addition, the filter also has the advantages of being active, reusable, and flame-retardant. This charged graphene aerogel filter (CGAF) is very stable and can withstand 10 times washing and 5-min burning.

A novel multifunctional coating prepared by internal and external inhomogeneous modification of porous fillers

Novel lypohydrophilic porous fillers that can function as micro-reservoirs to store lubricating oil as a low-friction and anticorrosive agent in a composite coating were developed. The novel oily particles were added to an epoxy resin (EP)-based coating to study the effect of lubricating oil on the anti-corrosion and the low-friction performance of the coating. The electrochemical impedance spectroscopy and the sliding wear tests demonstrated that the oily particles can significantly improve the barrier property and the wear-resisting performance of the EP coating. Furthermore, the friction coefficient of epoxy resin-25% lubricating celatom coating (0.4) was lower than that of the epoxy resin-25% PVDF coating (0.55), and the wear rate was lower by a factor of eight. The enhanced wear resistance can be mainly attributed to the lubrication performance of the lubricating oil stored in the porous particles. In addition, the hydroxyl group on the porous particles enhanced the crosslinking with the epoxy resin.

Anti-corrosion and wear resistance properties of polymer composite coatings: Effect of oily functional fillers

Abstract We herein report the development of carbon-modified porous fillers that function as micro-reservoirs to store lubricating oil as a low-friction and anticorrosive agent in a composite coating. These novel oily particles were added to an epoxy resin (EP)-based coating to study the effect of a lubricating oil on the anti-corrosion and friction performances of the coating. Analysis by electrochemical impedance spectroscopy and sliding wear tests demonstrated that the presence of particles containing the lubricating oil significantly improved the barrier properties and the wear resistance of the EP coating. It was therefore apparent that the carbon surface modification of the Celatom filler improved the compatibility of both the filler towards the resin. Thus, the addition of fillers containing lubricating oil further improved the wear resistance and anti-corrosion properties of the coatings.

Encapsulation of metal ions between the biopolymeric layer beads for tunable action on oil particles adsorption from oily wastewater

In the present scenario, the challenging task of oil recovery is highly important owing to its increased rate of oil production. Biopolymers are excellent materials for the water treatment process. However, in the adsorption process, the powder form or raw flakes could not be used in column studies as it causes a significant pressure drop. To overcome the above challenge, the biopolymers have been modified into usable bead forms. In this work, the iron incorporated alginate/chitosan (Fe-Alg/CS) and iron incorporated gelatin/chitosan (Fe-Gel/CS) hybrid composite beads were successfully synthesized and were effectively utilized for the removal of oil from oil in water emulsion. The synthesized hybrid composite beads were characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), energy dispersive analysis of X-ray (EDAX), powder X-ray diffraction (XRD), thermogravimetric analysis (TGA) and heat of combustion. Various influencing parameters viz., contact time, dose, pH of the emulsion, temperature and initial oil concentration were optimized for maximum oil removal capacity. The commonly used isotherms namely Freundlich, Langmuir, Tempkin, and D–R isotherms were used to check the suitability of the experimental data. The thermodynamic parameter results indicate that the oil adsorption was endothermic and spontaneous. The mechanism can be explained by different interactions such as surface complexation, electrostatic and hydrophobic interactions, which were adopted for the removal of oily particles at different pH levels. Thus, the experimental results presented herein indicate that the prepared hybrid composite beads can be utilized as the potential adsorbents for the removal of oil from oily wastewater.

Synthesis and characterization of chitosan/Mg-Al layered double hydroxide composite for the removal of oil particles from oil-in-water emulsion

The recovery of oil from oil-in-water emulsion has been investigated using chitosan/magnesium-aluminium layered double hydroxide hybrid composite (CS-LDHCs) by a single co-precipitation method. Resulting better adsorption efficiency of CS-LDHCs could be observed, indicating the synthesized material was effective to adsorb oil particles from oil-in-water emulsion at acidic pH (pH 3.0) than as-prepared LDH and raw chitosan. The enhancement of adsorption properties by CS-LDHCs material were attributed to the high content of LDH in chitosan, which makes the material more effective towards immobilization of oily particles. Batch experiment study has been elucidated by varying different physicochemical parameters such as time, pH, dose, initial oil concentration and temperature. The as-synthesized CS-LDHCs was characterized by various spectro analytical techniques viz., FTIR, SEM with EDAX, XRD, TGA and DSC analysis. To find out the best fit for the sorption process, the obtained adsorption equilibrium data was explained with Freundlich, Langmuir, Dubinin-Radushkevich and Tempkin isotherm models. The mechanism of adsorption process was demonstrated by calculating ΔG°, ΔH° and ΔS° values from thermodynamic parameters in order to understand the nature of sorption process. The schematic representation of oil removal using CS-LDHCs was explored in detail. This work provides an apparent proposal for the growth of oil removal technology.

Physicochemical characterization of oily particles emitted from different machining processes

Oily particles emitted from different machining processes can get deep into the respiratory system and have adverse effects on human health. But the toxic associated physicochemical characterization of the oily particles is still not fully understood. This study combined with an improved strategy and off-line analysis to obtain the characteristics of the oily particles emitted from different machining processes. A factory was selected for our study where the grinding, wet-lathing, dry-lathing, milling and intercritical hardening processes intensively lay together with operational workers. The results showed that the particle concentration of the various machining processes ranged from 2.1×105 to 2.8×105p/cm3 with a large proportion of fine and ultrafine oily particles. Most of these particles agglomerated into flakes having small spheres attached to them, but a special rod shape particles were observed in the milling processes. The oily particles contained Fe, Si, Na, Mg and Al, and the metallic elements had a comparable mass in both fine and coarse particles. In addition, ultrafine particles had higher oil portion than the larger particles. The results could be employed for exposure assessment and were helpful for industrial hygienists to develop better strategies for the removal of the particles from workplaces.

Electro-coagulation treatment of oily wastewater with sludge analysis

Experiments were carried out in a batch reactor to treat the oily effluent by electro-coagulation. The influence of operating parameters such as applied current, type of electrode and electrolysis time on electro-coagulation efficiency has been critically examined. The maximum percentage removal of chemical oxygen demand (COD) was 94% under optimum experimental conditions of pH 6.7, current density 6 mA/cm², electrolysis time 40 min, and using mild steel as anode. The remaining sludge in the reactor was analyzed by energy disperse analysis of X-rays (EDAX) and scanning electron microscope (SEM) analysis. The analysis confirms that the oily pollutant was removed by electroflotation and adsorption of the oily particles of precipitate during the electro-coagulation process. Electro-coagulation can be used as an efficient treatment technique for oily wastewater.