Polysulfone Microcapsules Research Articles

Highly efficient and stable adsorption of lithium from brine with microcapsules containing 1-phenylazo-2-naphthol and trioctylphosphine oxide.

Lithium extraction from salt lake brine is still challenging due to the existence of similar elements, e.g. sodium. In the present work, polysulfone (PSF) microcapsules containing 1-phenylazo-2-naphthol (HS) and trioctylphosphine oxide (TOPO) as extractants were successfully prepared by microfluidic technology for the separation of Li+ from brine with Li+ and Na+. The morphology, composition, and structure of HS-TOPO-based microcapsules were characterized systematically. The results showed that microcapsules consisting of 20 wt% (m m-1) polysulfone and 80 wt% (m m-1) 1-phenylazo-2-naphthol-trioctylphosphine oxide as the extractant, which was labeled as PSF/HS-TOPO-2/8, exhibited the best performance for Li+ adsorption. The separation factor (SF) of Li+ over Na+ is up to 653 and the adsorption capacity for Li+ in the simulated brine could reach 3.67 mg g-1 for microcapsules PSF/HS-TOPO-2/8, which demonstrated that Li+ can be separated with high selectivity. Besides, the kinetic results demonstrated that the adsorption followed quasi-secondary adsorption kinetic models, indicating that the adsorption mechanism of lithium by microcapsules involved chemisorption. After ten cycles of adsorption-elution, the maximum equilibrium adsorption capacity still remained at 87%. All these results demonstrate that PSF/HS-TOPO-2/8 microcapsules can be used as an efficient adsorber for the adsorption of Li+ from brine with high selectivity and stability.

PH-responsive smart composite coating with active anticorrosion and efficient scale inhibition properties

In this work, porous polysulfone (PSF) microcapsules were prepared using the method of mixed solvent volatilization, these microcapsules were used as a carrier, 1-hydroxyethylidene-1, 1-diphosphonic acid (HEDP) was used as an active substance for scale and corrosion inhibition, and stearic acid (SA) was used as a coating to prepare a pH-responsive smart microcapsule slow-release filler. Then, the smart microcapsules were added to a polyurea resin to prepare a pH-responsive smart composite coating with anti-corrosion and scale inhibition properties. The results showed that SA/PSF/HEDP microcapsules have significant pH-triggering activity in an alkaline environment. The alkaline supersaturated CaCO3 solution test showed that the composite coating has excellent scale inhibition performance. This is attributed to the in the microcapsules being released to the coating surface, achieving the purpose of complexation and solubilization. Local electrochemical impedance spectroscopic (EIS) proved that the SP/SA/PSF/HEDP composite coating has good corrosion resistance. This is attributed to the release of corrosion inhibitors, which can form a dense protective film on the metal. The scale inhibition efficiency of the composite coating was as high as 78.57 %, and the impedance modulus value is increased by three orders of magnitude.

Properties and Corrosion Resistance Mechanism of a Self-Healing Propane-1,2,3-Triol-Loaded Polysulfone Microcapsule Coating Loaded with Epoxy Resin.

Propane–1,2,3-triol-loaded polysulfone (PSF) microcapsules were prepared by the solvent evaporation method. The particle size of the microcapsules is about 140 μm. The shell wall thickness is about 17 μm approximately. The microcapsules have high thermal stability and antiwear performance. The self-healing coating was prepared by adding the prepared capsule into the epoxy resin coating. After electrochemical and corrosion immersion experiments, the resistance modulus of the coating added to the microcapsules was higher than the others in a 3.5 wt % NaCl corrosion solution, and it had the lowest corrosion current density, so the self-healing microcapsule coatings showed excellent healing ability and corrosion inhibition function for microcracks. This was attributed to the formation of a hydrophobic film after propane–1,2,3-triol was released from the damaged microcapsules.

Extraction chromatographic materials based on polysulfone microcapsules for the sorption of strontium from aqueous solution

Crown ether-loaded polysulfone (PS) capsules suitable for the separation and preconcentration of strontium from acidic nitrate media have been prepared and characterized. Specifically, PS macro- and microcapsules have been impregnated with the macrocyclic polyether di-tert-butylcyclohexano-18-crown-6 (DtBuCH18C6), either undiluted or as a solution in 1-octanol, and their performance in the extraction of strontium from nitric acid solution evaluated. The DtBuCH18C6-loaded microcapsules were found to exhibit strontium uptake efficiency significantly greater than that observed for the analogous macrocapsules, confirming earlier observations of a marked size-dependence of the behavior of extractant-loaded PS capsules. Comparison of the microcapsules to a commercial extraction chromatographic (EXC) material (Sr-resin) comprising DtBuCH18C6-loaded beads of poly(methyl methacrylate) (PMMA) of comparable size (50–100 μm), showed that the two materials exhibit similar strontium retention, uptake kinetics, and selectivity. The microcapsules provide higher column efficiencies, however, and when fully loaded with extractant, higher strontium ion uptake capacity.

New polysulfone microcapsules containing metal oxides and ([BMIM][NTf2]) ionic liquid for CO2 capture

CO2 emission from flue gas is one of the main sources of global warming. The development of new materials with enhanced CO2 adsorption is crucial to foster sustainable development. In this work, 1-Butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([bmim][NTf2]) ionic liquid (IL) was synthesized and combined to metal oxides (Fe2O3, CuO and TiO2) for further encapsulation in polysulfone (PSF) using emulsification method. Computational study using “ab initio” method was also performed. Scanning electron microscopy evidenced the uniform formation of the IL/metal oxide encapsulated polysulfone microcapsule. Transmission electron microscopy (TEM) and Scanning electron microscopy indicates the formation of microcapsules of around 1.0 μm containing a dense core (IL/metal oxide) when Fe2O3 was encapsulated by a polymer shell presenting better CO2 sorption compared to microcapsule containing CuO and TiO2. Thermogravimetric analysis (TGA) presents microcapsule thermal behavior indicating microcapsule lower degradation temperature when compared to neat PSF. IL encapsulation capacity was determined using acetone immersion test. Results indicated around 40 % of encapsulation capacity. Differential scanning calorimetry shows the complete disappearance of the IL (at -3.14 ℃) characteristic peak after the acetone immersion test confirming IL removal by the method. The residue wt.% calculated by TGA in air atmosphere was used to determine the metal oxide amount incorporated in the microcapsules. The CO2 sorption capacity of microcapsule with Fe2O3 shows an enhancement of around 47 % as compared to the neat-PSF. Here we reported the development of an effective solvent-free adsorbent for CO2 capture fostering industrial application.

High-capacity extraction chromatographic materials based on polysulfone microcapsules for the separation and preconcentration of lanthanides from aqueous solution

Extractant-loaded polysulfone (PS) capsules suitable for the separation and preconcentration of rare earth ions from acidic media have been prepared and characterized. Specifically, PS macro- and microcapsules have been impregnated with bis(2-ethylhexyl)phosphoric acid (HDEHP), and their performance in the extraction of europium (Eu3+) from nitric acid solution evaluated. The HDEHP-loaded microcapsules were found to exhibit sorption efficiency superior to those of analogous macrocapsules. Comparison to a conventional (i.e., commercial) extraction chromatographic (EXC) material (Ln•Resin), comprising HDEHP-loaded beads of poly(methyl methacrylate) (PMMA) of comparable size (50–100 µm), showed that the capacity of the HDEHP-loaded microcapsules for europium is ca. 2.5-fold greater than that of the conventional material. This larger capacity is the apparent result of both the higher extractant loading achievable with the microcapsules and an unexpected change in the complexation stoichiometry of europium by HDEHP upon extractant encapsulation. The microcapsule-based sorbent equaled or exceeded the performance of the commercial EXC material in other respects as well, most notably uptake kinetics and column efficiency, making it a promising alternative to established EXC resins.

Extraction of Cu2+ from aqueous solutions using microcapsules containing ionic liquid [BMIM]PF6

Polysulfone (PSF) microcapsules filled with ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6] were successfully prepared via solvent evaporation method. The encapsulation capacity of 38.0% was achieved. Microcapsules showed a spherical, porous honeycomb structure. The size of microcapsules was approximately 110 μm and the thickness was approximately 10 μm. Microcapsules have excellent thermal stability, with a higher thermal degradation onset temperature of 360°C compared to traditional extractant-loaded microcapsules. Microcapsules were used to extract Cu2+ from aqueous solutions. The effect of chelator, pH, PSF, and ionic liquid on the extraction rate were studied. When chelator was added in aqueous solutions, and the pH of aqueous solutions was 4.5, the extraction rate of microcapsules reached the maximum value, which was 99.0%. These PSF microcapsules containing [BMIM][PF6] showed potential ability in the treatment of wastewater.

Preparation and application of polysulfone microcapsules containing tung oil in self-healing and self-lubricating epoxy coating

Polysulfone microcapsules containing tung oil were synthesized by a solvent evaporation method. The mean diameter and wall thickness of the synthesized microcapsules were approximately 130μm and 9μm, respectively. High thermal stability of the microcapsules with a thermal degradation onset temperature of 350°C was obtained. The multi-functional coating was fabricated by incorporating the microcapsules containing tung oil into an epoxy matrix. The self-healing and self-lubricating functions were evaluated by corrosion and tribology test. 10wt% microcapsules embedded in epoxy coating offered optimum results. The microcapsules showed excellent anticorrosion performance in scratched coatings, which was attributed to the formation of a cross-linked polymer film after tung oil was released from the damaged microcapsules. The frictional coefficient and wear rate of the self-lubricating coating decreased significantly as compared to the neat epoxy. The formation of a transfer film from releasing tung oil and the entrapment of wear particles in the cavities left by the ruptured microcapsules were the major antifriction mechanism.

Microcapsules containing ionic liquid [A336][P507] for La3+/Sm3+/Er3+recovery from dilute aqueous solution

AbstractThe efficacy of polysulfone microcapsules encapsulating ionic liquid [trialkylmethylammonium][di(2-ethylhelxyl) orthophosphinate] ([A336][P507]) for the extraction of La3+, Sm3+ and Er3+ from dilute aqueous solutions was investigated. Microcapsules were synthesized using coaxial microfluidic method, and subsequently encapsulated with extractant [A336][P507]. The kinetics data were fitted well by pseudo-second-order equation and Crank model, and the kinetics parameters were evaluated. The extraction rate had the order of Er3+>Sm3+>La3+. The isotherm data were analyzed by Langmuir model and shifted Langmuir model. The extraction capacities of La3+, Sm3+ and Er3+ were 58.4, 56.6 and 81.7 mg/g, respectively. The dependency of stripping performance on HNO3 concentration was measured. The regeneration of microcapsules was evaluated using cycling extraction experiments.

Fabrication of Thermally Stable Polysulfone Microcapsules Containing [EMIm][NTf2] Ionic Liquid for Enhancement of In Situ Self‐Lubrication Effect of Epoxy

Microcapsules containing an ionic liquid (IL) are potential candidate materials for preparing in situ self‐lubricating composites with excellent tribological properties. 1‐ethyl‐3‐methylimidazolium bis[(trifluoromethyl) sulfonyl]imide ([EMIm]NTf2) IL encapsulated polysulphone microcapsules are synthesized. The mean diameter and wall thickness are about 128 μm and 10 μm, respectively. Microcapsules have excellent thermal stability, with a thermal degradation onset temperature of 440 °C compared to traditional lubricants‐loaded microcapsules. In situ self‐lubricating composites are prepared by incorporating the IL‐encapsulated microcapsules into epoxy matrix. When the concentration of the IL microcapsules is 20 wt%, the frictional coefficient and specific wear rate of composites are reduced by 66.7% and 64.9% under low sliding velocity and middling applied load conditions, respectively, as compared to the neat epoxy. The tribological behavior of the self‐lubricating composites is further assessed in different applied load and sliding velocity conditions. The in situ self‐lubricating mechanism of composites is proposed.image

Preparation of high thermal stability polysulfone microcapsules containing lubricant oil and its tribological properties of epoxy composites

Polysulfone (PSF) microcapsules containing lubricant oil have been successfully prepared using solvent evaporation method. The results show that lubricant oil was successfully encapsulated and the encapsulation capacity of about 56.0 wt.% was achieved. The uniform microcapsules have nearly spherical shape and quite smooth outer surface. The mean diameter is approximately 156 and 169 μm by using different dispersant solutions. The wall material is porous in structure with wall thickness of about 20 μm. The initial decomposition temperature of PSF is 480 °C. It is higher than traditional poly(urea-formaldehyde) (PUF) and poly(melamine-formaldehyde) (PMF) wall materials with 245 °C and 260 °C initial decomposition temperature, respectively. High thermal stability of PSF microcapsules can be considered as additives in high temperature resistant polymer materials. The frictional coefficient and wear rate of epoxy composites decreased significantly by incorporating microcapsules containing lubricant oil into epoxy. When the concentration of microcapsules was 25 wt.%, the frictional coefficient and specific wear rate were reduced by 2.3 and 18.3 times, respectively, as compared to the neat epoxy.

Fabrication of highly hydrophobic organic–inorganic hybrid magnetic polysulfone microcapsules: A lab-scale feasibility study for removal of oil and organic dyes from environmental aqueous samples

In this work, three kinds of organic–inorganic hybrid materials (vinyl benzene linear polymer modified SBA-15, attapulgite and halloysite nanotubes) in the shape of powder and the corresponding magnetic polysulfone microcapsules were developed for removal of oil and dyes from environmental aqueous samples, respectively. As determined from the oil and dye adsorption studies, the developed magnetic polysulfone microcapsules exhibited high adsorption capacity of 13.8–17.3g/g for oil. The prepared functionalized materials and the corresponding microcapsules can remove 85.0–91.6% and 81.8–87.8% Sudan I in 80min and 7.6h, respectively. The results showed a significant improvement in their adsorption capacities and removal efficiencies compared to the parent matrices, indicating that the introducing of the vinyl benzene linear polymer was a major factor in the removal of the hydrophobic pollutants. At the same time, the adsorption capacity for the investigated pollutants also depended on the textural feature of matrix itself. In view of the utilization of low-cost clay minerals (attapulgite and halloysite nanotubes), these proposed functionalized materials and the corresponding magnetic polysulfone microcapsules had a great promise to be used as an efficient sorbent for removal of pollutants from environmental aqueous samples.

Extraction of lanthanides by polysulfone microcapsules containing EHPNA. II. Coaxial microfluidic method

Controllable preparation of small-size polysulfone microcapsules (MC) containing 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (EHPNA) by coaxial microfluidic method was focused on. N2 gas was used as continuous phase to disperse the polymer solution. The influence of polysulfone (PSF) content in the polymer solution and N2 gas flow rate on the structural properties and loading ratio of microcapsules was investigated. The mean diameter of prepared microcapsules was between 0.90 and 1.60 mm. Ultrasound method was adopted to import EHPNA into microcapsules. A very high extractant loading ratio of 6.21 g-EHPNA/g-PSF was achieved when the pore volume was 6.89 mL/g. The extraction performance was determined with lanthanides as the recovered components and with the prepared microcapsules as the separation agent. Close-packed microcapsules enjoyed a fast extraction kinetics. The maximum uptakes of La3+, Sm3+ and Er3+ were 3.02×10−4 mol/g, 8.05×10−4 mol/g and 5.58×10−4 mol/g, respectively. Microcapsules were reused seven times and showed very good stability. It is promising to apply the microcapsules into the extraction column and realize continuous operation.

Extraction of lanthanides by polysulfone microcapsules containing EHPNA. I. Piercing method

Since the conventional liquid-liquid extraction method suffered from a series of problems such as inefficiency of one stage extraction, vast device occupation and severe emulsification, we adopted microcapsule (MC) technique to change the former liquid-liquid extraction to liquid-solid extraction. Firstly, the piercing method was performed to prepare the empty polysulfone (PSF) microcapsules, which was easy to implement and control. Secondly, the ultrasonic approach was utilized to prepare the functional microcapsules containing 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (EHPNA). We focused on a key factor of the molar ratio of PSF over 1-Methyl-2-pyrrolidinone (NMP), attaining a loading ratio as high as 7.21 g-EHPNA/g-PSF. Thirdly, we examined the kinetics and thermodynamics of extraction. Kinetic results demonstrated that equilibrium was reached within two hours, with an extraction rate of Sm3+≈Er3+>La3+; Thermodynamic results showed that the extraction of lanthanides complied with the Langmuir law, with an extraction capacity of 0.25–0.30 mmol/g-microcapsule. Fourthly, stripping experiment indicated that three hours were required to accomplish equilibrium for La3+ and Sm3+ while longer hours for Er3+. Finally, seven extraction-stripping cyclic experiments were performed for three mixed elements, the results of which revealed that Sm3+ and Er3+ maintained constantly high extraction amount whilst La3+ leveled off at approximately 50%. This proposed polysulfone microcapsule containing EHPNA is suitable to be applied to extraction and concentration of rare earth metals.

Adsorption of caprolactam from aqueous solution by novel polysulfone microcapsules containing [Bmim][PF6

Polysulfone (PSF) microcapsules containing ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF6]) as extractant have been successfully prepared using solvent evaporation method and used in removing caprolactam from water. The results showed that ionic liquid [Bmim][PF6] was successfully encapsulated by PSF and the encapsulation capacity of 32.44% was achieved. Systematic studies on the effect of concentration of ammonium sulfate solution, caprolactam adsorption equilibrium, kinetic and isotherm by PSF@[Bmim][PF6] capsules were carried out. The results showed that increasing the concentration of ammonium sulfate solution, initial concentration of the caprolactam and the adsorption time were good for adsorption. The adsorption kinetics of caprolactam followed pseudo-second-order model and the Freundlich equation described the adsorption process better than the Langmuir equation. These PSF@[Bmim][PF6] capsules showed potential ability in the treatment of wastewater.

Polysulfone/Vanillin Microcapsules for Antibacterial and Aromatic Finishing of Fabrics

Microencapsulation technology is being more and more applied in the textile industry because microcapsules can confer additional properties to conventional fabrics. In this context, polysulfone microcapsules containing vanillin were prepared, and their morphology, thermal stability, and antibacterial properties against Staphylococcus aureus were assessed. The microcapsules were fabricated onto 100% cotton fabrics by a coating technique. The resistance of the coating to several washing cycles was studied, and the durability of the aromatic finishing was determined. Capsules were stable in the range between 20 and 100 °C, and they inhibited the growth of the bacteria at 37 °C for, at least, one week. Most of the capsules added to the fabric were flushed away between the first and second washing cycle; however, some capsules were still observed after the fifth washing. Finally, a survey was conducted in order to know how consumers perceived the aroma, before and after several washings. Survey data was statistically analyzed, and a model was built, which allowed the probability of maintained aromatic finishing for specific washing cycles to be predicted. Thus, this work sets the basis for further development of fabrics with antimicrobial activity and pleasant aromatic finishing based on polysulfone/vanillin capsules.

State of the Art of Polysulfone Microcapsules

State of the Art of Polysulfone Microcapsules

Polysulfone microcapsules with different wall morphology

AbstractFor the production of polysulfone microcapsules, a process was proposed, which allowed the obtaining of capsules with different wall morphology. A polysulfone solution was projected to a precipitation bath. Three solvents were assessed: N,N‐dimethylformamide, N,N‐dimethylacetamide, and N‐methyl‐2‐pyrrolidone. Precipitation baths were composed by water, pure or mixed with solvent. Surfaces and cross–sections of different preparations were observed by Scanning Electron Microscopy. The study was focused on capsules of 30 ± 10 µm of diameter. Microcapsules surfaces were porous and two different structures were distinguished in the cross‐section: macrovoids and sponge‐like structures. High concentration of solvent in the precipitation bath reduced the porosity of the surface and the macrovoids of the wall, thus favoring sponge‐like structures. The present work set some bases for a better control of polysulfone microcapsules morphology. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Polysulfone/Vanillin Microcapsules Production Based on Vapor-Induced Phase Inversion Precipitation

Polysulfone microcapsules containing vanillin were previously prepared by using a method based on phase inversion by immersion precipitation. Liquid water was used as the nonsolvent. Characteristics of that product were promising but further research was required. This work aims to prepare similar capsules by using vapor water as nonsolvent (vapor-induced phase inversion precipitation). The precipitation technique effect on capsules morphology and performance was studied. The products were morphologically characterized and significant differences were found only in the cross-section structure: if liquid water was used, macrovoids appeared in the wall; whereas by using water vapor, sponge-like structures were obtained. Finally, vanillin release was characterized, and release trends were the same for both preparations. Thus, the proposed process allowed the obtainment of capsules with similar performance. In addition, the use of water vapor showed a reduction of water consumption during the preparation.

Preparation of Uniform Microcapsules Containing Ionic Liquid for Caprolactam Extraction

Microencapsulating ionic liquid is an effective way to overcome the loss of ionic liquid in the extraction process. A phase inversion method was used to form microcapsules containing 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM] [PF6]. The oil phase, composed of [BMIM][PF6], polysulfone and dichloromethane, was dropped into the 0.2 wt% gelatin aqueous solution using nitrogen gas pressure to form droplets. As dichloromethane evaporated completely, polysulfone microcapsules containing [BMIM] [PF6] were obtained. The microcapsules were characterized using a polarizing microscope, a laser particle size analyzer and a thermogravimetric analyzer. Moreover the microcapsules were performed some effect on caprolactam extraction from water.