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Poly(vinyl alcohol) (PVA) / modified carbon nanotubes (CNTs) mixed matrix membranes (MMMs) were prepared to study the pervaporation (PV) dehydration of aqueous azeotrope isopropanol mixture. CNTs were modified by wrapping different amount (5–14 wt%) of poly(styrenesulfonate) (PSSA) and poly(vinylpyrrolidone) (PVP) on CNT respectively. ATR, XRD, FESEM, TGA and tensile tests were used to characterize the modified carbon nanotubes and the membranes. For carbon nanotubes wrapped lower amount of poly(styrenesulfonate), the pervaporation results showed that the separation factor remarkably increased and the flux slightly decreased by increasing the content of the modified nanotubes from 0 to 3 wt%, while a reverse trend was observed with further incorporation of the nanotubes up to 5 wt%. Interestingly, increasing poly(styrenesulfonate) density around nanotubes’ sidewalls led to non-ideal effects such as interchain coiling of poly(styrenesulfonate) and formation of rigidified coiled-coil aggregations, so the best PV results were achieved at lower wrapping of poly(styrenesulfonate). However, wrapping nanotubes by poly(vinylpyrrolidone) resulted in fabrication of nanocomposites without evidence of defects or agglomerations and enhanced thermal and mechanical properties. Among all prepared membranes, the best PSI (303) was obtained by embedding 4 wt% of poly(vinylpyrrolidone)-wrapped-nanotubes into poly (vinyl alcohol) that could be attributed to good compatibility and interactions between the fillers and the matrix. Hydrogen bonding between carbonyl groups of poly(vinylpyrrolidone) and hydroxyl groups of poly(vinyl alcohol), formation of hydrophilic channels and helical wrapping of poly(vinylpyrrolidone) chains instead of interchain coiling were responsible for the observed improvement in separation performance of the membranes containing PVP-wrapped-CNTs.

In this work, the photocatalytic degradation of ciprofloxacin (CIP) by black Ti3+/N-TiO2 under visible LED light irradiation (b-N-TiO2/LED) was studied for the first time. Characterization of the prepared photocatalyst was performed by XRD, UV–Vis DRS, FE-SEM, EDS, HRTEM, and BET techniques. The b-N-TiO2 nanoparticles with high surface area of near 100 m2 g−1 and narrow band gap of 2.0 eV, exhibited a remarkable photocatalytic performance on the degradation (100 %) and mineralization (82 %) of CIP under visible LED light irradiation. The maximum degradation was found at reaction time = 70 min, initial CIP concentration = 0.5 mg L−1, pH = 6.7, and catalyst dosage = 0.43 g L−1. Based on the results, both the hole (h+) and hydroxyl radical ( OH) played a major role than the superoxide radical ( O2−) in CIP degradation. Although common coexisting anions in water had a slight negative effect on CIP degradation; humic acid (HA), especially in higher amounts, showed a considerable inhibitory effect on degradation process. Besides, the intermediates of CIP degradation were ultimately transformed into simple compounds. Accordingly, toxicity assessments revealed that the treatment of CIP solution by b-N-TiO2/LED process remarkably resulted in diminished toxicity compared to the untreated controls. The energy utilized in this study was far less than that used in other studies. Moreover, we found that b-N-TiO2 had desirable stability and can be reused for more than five runs of experiments. Collectively, based on our findings, the b-N-TiO2/LED process is a promising, low cost and feasible candidate can be used for degradation and mineralization of antibiotics like CIP in real water samples.

In the present study, two seriess of poly (urethane urea)s (PUUs) membranes containing aromatic and aliphatic side chains with different sizes were used for separation of higher hydrocarbons from methane. Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetery (DSC), fractional free volume (FFV) estimation, and gas permeation measurements (CH4, C2H6, C3H8) were done to characterize the membranes. Bulkier or longer side chains in aromatic and aliphatic substituted PUUs provided enhanced phase separation, lower glass transition temperature and higher gas permeability. Fractional free volume (FFV) as a significant factor controlling gas separation had a reverse trend in both series by increasing the size of side chains. The main findings confirmed the capability of higher phase separated PUUs for hydrocarbon separation. The highest permeability and selectivity was obtained by the longest side chain based PUU with propane permeability of 186 barrer and propane/methane selectivity of 6.51.

Background: Diabetes mellitus is one of the most common endocrine diseases. Studying the plants and effective compounds from plant extracts to prevent diabetes has become recently important. Objectives: The present study aimed to investigate the effect of hydroalcoholic extract on blood glucose level, biochemical parameters, fat profile, and serological parameters in diabetic rats. Methods: In this study, 42 Wistar outbred rats were studied. The rats were divided into seven groups namely the control group, the control group with 200 and 400 mg/kg body weight of the Descurainia sophia extract, the diabetic rats, the diabetic rats receiving 0.4 mg/kg of glibenclamide, and the diabetic rats treated with 200 and 400 mg/kg of the D. sophia extract. Streptozotocin was used for the diabetic rats through intraperitoneal injection, and extract was used by gavage method. One-way ANOVA was used to analyze the research data in SPSS software. Results: The results showed that administration of D. sophia extract to diabetic rats reduces the blood glucose, biochemical enzymes level, triglycerides, total cholesterol, and LDL cholesterol. There was no significant difference in cholesterol levels. In the rats which received the extract, the amount of albumin decreased and the amount of urea and creatinine increased significantly. Conclusions: Based on the research findings, it can be concluded that this extract can be useful in preventing diabetes by reducing blood glucose, changing biochemical enzyme level, fat profile, and serological parameters; as D. sophia hydroalcoholic extract contains various compounds.

In this research, the effect of polyethylene glycol (PEG) molecular weight on permeability and selectivity of polysulfone/polyethylene glycol (PSF/PEG) composite membrane is investigated. Polyethylene glycol with molecular weights of 4000, 6000, and 10,000 is applied. It is shown from the results that PEG applied in composite membranes with molecular weight of 1000 had the best diffusivity in comparison with the other composite membranes containing PEG with lower molecular weights. In addition, it is perceived that the permeability of CO2 from PSF/PEG10000 composite membranes has increased with enhancing weight percent. CO2 permeability into PSF/PEG composite membranes containing 20 wt% PEG10000 is calculated 7.64 barrer (1 barrer = 10−10 cm3 (STP) cm/cm2 s cmHg). The ideal selectivity for CO2/N2 gas pair in PSF pure membrane and composite membranes containing 10 wt% and 20 wt% PEG10000 are calculated 26.57, 30.61, and 32.12, respectively. Finally, the morphology and membrane structure of the membrane were evaluated with infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and tensile strength test.

Mixed matrix membranes (MMMs) base on poly(vinyl alcohol) (PVA) incorporated with titanate nanotubes (TNTs), cross-linked with glutaraldehyde, were prepared. The hydrothermally synthesized TNTs and the membranes were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffractometer (XRD), Thermogravimetric analysis (TGA), Field emission scanning electron microscope (FESEM), and tensile strength analyses. The prepared nanocomposite membranes were used for dehydration of isopropanol by pervaporation process. The effects of the weight fraction of TNTs, feed temperature, and concentration on the performance of the membranes were investigated. The results indicated that incorporation of hydrophilic TNTs could effectively improve the separation performance of PVA membranes in terms of both permeability and separation factor. Based on the results, the separation factor of all nanocomposite membranes was increased. Moreover, the membrane containing 4 wt% of TNTs exhibited the highest separation factor value of 5520, while the maximum value of flux was about 0.126 kg/m 2 h for the membrane containing 10 wt% TNTs. So, there was about 794% and 741% enhancement in separation factor and flux respectively, compared to the pristine PVA membranes. Consequently, the results confirm incorporating TNTs in the PVA matrix could improve the separation of water from isopropanol aqueous solutions effectively due to the intrinsic hydrophilicity and special structure of TNTs.

A series of poly(urethane-urea) (PUU) membranes based on contributing hard segments in gas separation were prepared using two novel bulky chain extenders, polytetramethylene-glycol, isophorone and hexamethylene-diisocyanate. The chain extenders were synthesized by cyanuric chloride, aniline/naphthylamine and hydrazine. According to FTIR, AFM and DSC, bulkier PUU membranes showed more phase separation and lower glass transition temperature consistent with higher fractional free volume, which were correlated with single (CO2, CH4, O2 and N2) and mixed (CO2:N2 and CO2:CH4) gas permeation results. The main findings indicate these polyurethanes serve efficiently designed molecular structures favoring bulky hard segments contribution in gas separation. The bulky PUU membranes afford simultaneous increased permeability and selectivity, while maintaining high tensile properties. Enhanced O2/N2 diffusivity selectivity by bulkier PUU and CO2 sorption/desorption study by Ellipsometry confirmed hard segments’ association, too. The bulkiest membrane provided 126% and 54% improvement for single CO2 permeability and CO2/N2 selectivity compared to linear one.

In the present work, the response surface method software was used with five measurement levels with three factors. These were applied for the optimization of operating parameters that affected gas separation performance of polyurethane–zeolite 3A, ZSM-5 mixed matrix membranes. The basis of the experiments was a rotatable central composite design (CCD). The three independent variables studied were: zeolite content (0–24 wt%), operating temperature (25–45 °C) and operating pressure (0.2–0.1 MPa). The effects of these three variables on the selectivity and permeability membranes were studied by the analysis of variance (ANOVA). Optimal conditions for the enhancement of gas separation performances of polyurethane–3A zeolite were found to be 18 wt%, 30 °C and 0.8 MPa respectively. Under these conditions, the permeabilities of carbon dioxide, methane, oxygen and nitrogen gases were measured at 138.4, 22.9, 15.7 and 6.4 Barrer respectively while the CO2/CH4, CO2/N2 and O2/N2 selectivities were 5.8, 22.5 and 2.5, respectively. Also, the optimal conditions for improvement of the gas separation performance of polyurethane–ZSM 5 were found to be 15.64 wt%, 30 °C and 4 bar. The permeabilities of these four gases (i.e. carbon dioxide, methane, oxygen and nitrogen) were 164.7, 21.2, 21.5 and 8.1 Barrer while the CO2/CH4, CO2/N2 and O2/N2 selectivities were 7.8, 20.6 and 2.7 respectively.

Novel heterogeneous cation exchange membranes, based on poly (ether sulfone) and cation exchange resin, were prepared with the addition of protonated and sulfonated Montmorillonite (MMT) nanoparticles. Detailed investigations were then carried out studying the morphology, physical properties and the performance of membranes. It is observed that addition of MMT, leads to a substantially better distribution of ion exchange resin in the polymer matrix. This leads, at low loadings of MMT (0.5 wt.%), to membranes that are more hydrated, more hydrophilic and with higher ion exchange capacities. Especially at these low MMT loadings, substantially better membrane performance is observed, with higher permselectivities, lower areal resistances and increased ion transport during electrodialysis. A very surprising effect is that the addition of MMT has a strong effect on the selectivity of the membranes, especially towards Mg2+. A high affinity of the nanoclay towards Mg2+, selectively slows down Mg2+ transport through the nanoclay containing membrane. At low MMT loadings this leads to a much higher areal resistance for Mg2+, while for Na+ and Ca2+ the areal resistance is decreased. This leads to resistance based selectivities of 5.5 for Na+/Mg2+ and 4.5 for Ca2+/Mg2+. Under more challenging electrodialysis operation selectivities become lower, but persist at 2.6 for Na+/Mg2+ and 2.04 for Ca2+/Mg2+, outperforming commercial Ralex membranes. Overall, the protonated clay leads to slightly better membrane performances and selectivities than the sulfonated clay, likely due to a better compatibility with PES.

Poly(vinyl chloride) (PVC)/SiO2 nanocomposite hollow-fiber membranes with different nano-SiO2 particle loadings (0–5 wt %) were fabricated using the dry-jet wet-spinning technique. Effects of SiO2 nanoparticles on the morphology of the prepared hollow-fiber membranes were investigated using scanning electron microscopy. Transport and antifouling properties of the fabricated membranes were evaluated by conducting pure-water permeation, solute rejection, and fouling resistance experiments. These studies indicated that incorporating silica nanoparticles into the PVC matrix during phase inversion lowers the hydraulic resistance through the membrane and narrows the selective membrane pores. Moreover, the nanocomposite membranes showed better antifouling properties compared to the pristine membrane during the ultrafiltration of a milk solution because of improved hydrophilicity and uniform dispersion of the nanoparticles. This work indicates that embedding silica nanoparticles into the PVC matrix is a promising method for producing cost-effective hollow-fiber ultrafiltration membranes with superior transport and antifouling properties.

This paper presents a study on control of nanoparticles dispersion in the hard and soft segments of a polyurethane (PU) membrane, via adjusting surface groups of the nanoparticles. The dispersion control allows for tailoring physical and transport properties of the membrane. PU-based mixed-matrix membranes (MMMs) embedded with cyanuric chloride and its derivatives, melamine, and 2,4,6-trihydazino-1,3,5-triazine (THDT) nanoparticles, are prepared. The MMMs are characterized using FTIR, XRD, TGA, DSC, and SEM analyses, and tensile strength tests. Peak assignment of the bonded carbonyl, crystallinity change, mechanical properties of the membranes, possible hydrogen-bonding of the PU backbone and the nanoparticles, and permeation tests indicate that cyanuric chloride nanoparticles are dispersed in the hard segments, whereas melamine and the THDT nanoparticles are distributed in the soft domains. As the cyanuric chloride nanoparticle concentration of the MMMs increases, the gas permeabilities and O 2 /N 2 , CO 2 /CH 4 and CO 2 /N 2 selectivities of the membranes increase. In the case of THDT and melamine, as the filler loading increases, the permeabilities of the gases decrease, whereas O 2 /N 2 , CO 2 /CH 4 and CO 2 /N 2 selectivities increase. A 10 wt% incorporation of THDT into the PU increases CO 2 /N 2 and CO 2 /CH 4 selectivities by 92% and 75%, respectively. These results point to the potential of cyanuric chloride nanoparticles for simultaneous improvement of gas permeability and selectivity, and the potential of melamine and THDT nanoparticles for preparation of highly selective nanocomposite membranes for CO 2 removal.

10 figures, 5 tables., A series of polysulfone (PSF) membranes were prepared using different solvents: dimethylformamide (DMF), tetrahydrofuran, dimethylacetamide, and n-methyl-2-pyrrolidone (NMP). The PSF membrane prepared by NMP showed the highest gas permeability. The influence of propionic acid as a Lewis acid on gas separation properties of the PSF was explored. The PSF membrane prepared by the casting solution containing 25 wt% PSF, 35 wt% propionic acid, and 40 wt% NMP showed a superior gas separation performance. The gas permeation measurements indicated that incorporating 30 wt% γ-alumina nanoparticles into the PSF matrix resulted in about the respective 43% and 41% increase in CO2 and O2 permeability together with a rise in CO2/CH4 and O2/N2 selectivities (13% and 7%, respectively). Furthermore, by rearranged modified Maxwell model, the role and nature of the interfacial layer in the PSF-based mixed matrix membranes were mathematically analyzed considering a reduced permeability factor., Beatriz Zornoza acknowledges the “Juan de la Cierva” Program (IJCI-2016-30776).

Diabetes mellitus is a metabolic syndrome characterized by elevated blood glucose. The α-glucosidase enzyme is responsible for the hydrolysis of carbohydrates. This in silico study aimed to evaluate the inhibitory effects of the isolated compounds from Allium sativum L. on α-glucosidase. At first, sulfur and phenolic compounds of A. sativum L. were obtained from PubChem database, and α-glucosidase enzyme structure was obtained from Protein Data Bank. Toxicity class of compounds and the Lipinski parameter were predicted by Toxtree and Protox II and the Swiss ADME tools, respectively. Finally, the molecular interaction analysis between α-glucosidase and compounds from A. sativum L. was performed by AutoDock 4.2.6. Molecular interactions were investigated using Discovery Studio Visulizer and Ligplot 2.1 program. All of the selected sulfur and phenolic compounds from A. sativum L. followed the Lipinski’s rules, had an acceptable binding energy, and lacked toxicity; therefore, they were appropriate candidates for α-glucosidase inhibition. Among these compounds, methionol and caffeic acid showed the lowest binding energy, and the highest inhibitory effect on α-glucosidase enzyme with − 3.9 and − 4.8 kcal/mol, respectively. These compounds also indicated the lower binding energy than the standard inhibitor (miglitol). Among the sulfur and phenolic compounds in A. sativum L., methionol and caffeic acid were predicted to be the powerful inhibitors, due to having more hydrogen binds and hydrophobic interactions with the active site of α-glucosidase.

Two types of poly(urethane-urea)-based mixed matrix membranes containing hyperbranched structures of surface-modified silica nanoparticles were fabricated. The stepwise surface modification of nanoparticles was done based on aminopropyltriethoxysilane, cyanuric chloride, and ethylenediamine. FTIR, TGA, elemental analysis, and SEM-EDX were served to characterize the modified particles. The incorporation of the nanoparticles into poly(urethane-urea)s (PUUs) altered the phase separation degree of soft and hard segments, elevated the glass transition of soft segments and reduced the chain order. MMM containing the optimal distribution of 5 wt% modified silica showed improved mechanical and gas separation properties with 20–25% and 30–36% enhancement in CO2 permeability and CO2/N2 selectivity, respectively. The presence of long adsorbent chains with NH moieties on the particles improves the particle distribution in the matrix, thereby enhanced CO2 permeability up to 5 wt% particle content. At higher loadings, the agglomeration of the particles led to the formation of non-selective channels for gas diffusion and reduced gas separation performance and mechanical properties.

In this study, TiO2 nanoparticles were functionalized by grafting polymerization of methoxy poly(ethylene glycol) methacrylate (MPEG) onto the nanoparticle surface. Functionalized TiO2 nanoparticle was used as nanofiller to prepare poly(vinyl alcohol) (PVA) based nanocomposite (NC) membranes through solution mixing method. The thermal and mechanical properties of PVA/PMPEG-TiO2 membranes were improved compared to pristine PVA membrane due to well dispersion and high compatibility between the inorganic fillers and the polymer matrix. Gas permeation and selectivity properties of PVA/PMPEG-TiO2 NC membranes with various TiO2 contents were also studied for O2, N2, CH4 and CO2. Gas permeability improvement was seen for studied gases, especially for CO2. In addition, the results showed higher CO2/N2 selectivity up to 49.36% for 3 wt% TiO2 containing NC membranes.

Sugarcane bagasse was pretreated with sodium carbonate, sodium sulfite, and sodium acetate in concentrations of 0.5 M and 0.25 M, as well as hydrothermal pretreatment, to break down its structural recalcitrance and improve biogas and ethanol production. The pretreatments were conducted at 100, 140, and 180 °C for 1 h. The highest biogas and ethanol production was observed for sugarcane bagasse pretreated with 0.5 M sodium carbonate solution at 140 °C, which was 239 ± 20 Nml CH4/g VS, and 7.27 ± 0.70 g/l, respectively, containing gasoline equivalents of 164.2 ± 14.3 l/ton of raw bagasse and 147.8 ± 14.2 l/ton of raw bagasse, respectively. The highest gasoline equivalent was obtained for biogas production from the substrate pretreated with 0.5 M sodium sulfite solution at 100 °C (190.2 ± 2.1 l/ton of raw bagasse). In comparison to sodium carbonate and sodium sulfite, sodium acetate had less effect on biofuel production and was comparable with hydrothermal pretreatment. In contradiction to sodium acetate pretreated bagasse, in which increased pretreatment temperature intensified biofuel production, a reduction of biofuel production was observed for sodium carbonate and sodium sulfite pretreatment when temperature was increased from 140 to 180 °C. Besides considerable amounts of biofuel production at the best conditions obtained, over 762 and 543 kilotons of equivalent CO2 can be reduced annually in Iran by biogas and ethanol production from sugarcane, respectively.

Minimum quantity lubrication (MQL) technique is an efficient and eco-friendly method of lubricant application in machining processes. The lubricant type applied in this technique is not only important in relation to environmental aspects but also has a great effect on machining efficiency. Nanolubricant (nanofluid) is composed of nanoparticles suspended in base oil and shows prominent lubrication performance. In the present study, the effects of minimum quantity nano-lubrication (MQNL) in surface grinding of Tungsten carbide grade YG8 is experimentally investigated. The nanolubricants applied in the experiments include MoS2, graphite, and Al2O3 nanoparticles (with varying concentration) dispersed in two different base oils- mineral oil (paraffin) and vegetable oil (sunflower). The grinding outputs such as specific energy, cutting force, and surface quality were used as measurands for determining the process efficiency. Furthermore, performance evaluation of MQNL in grinding process of WC material was performed by comparing the grinding outputs at different environment such as dry, wet, and MQL. The results show that, if nanoparticles are selected properly, MQNL technique is an effective method to improve the process efficiency by reducing the grinding force, specific energy, and increasing surface quality.

This paper presents new mixed-matrix membranes (MMMs) synthesized via incorporating hexamethylenetetramine dicyanamide cadmium nanoparticles, a metal organic framework (MOF), into the polysulfone (PSF) matrix. The MMMs are characterized using FTIR and SEM analyses, and their gas permeation properties are evaluated at different MOF loadings and various pressures. The results show that the nanoparticle is compatible with the polymer and distributes homogenously in the matrix. Compared to the pristine PSF membrane, the MMM with 2.5 wt. % of the MOF nanoparticles has lower CO2, CH4, N2 and O2 permeabilities but significantly higher CO2/CH4, CO2/N2 and O2/N2 gas pair selectivities (i.e., 41.66, 20.08 and 5.09, respectively, which are 42.6, 61.6 and 60.02 % higher). As the total pressure increases, the gas permeabilities of the pristine PSF membrane and the MMMs decrease, but their sieving abilities increase. These results suggest that gas selectivities of high free-volume polymers with poor sieving abilities can be improved by incorporating the MOF into the polymer.

Polymer/nanoparticle mixed matrix membranes (MMMs) is one of the most important topics in gas separation field. In this study, to improve gas separation efficiency, methoxy poly(ethylene glycol) me...

This Study involves preparation and characterization of polyurethane (PU) and polyurethane/poly(vinyl alcohol) (PU/PVA) blend membranes for gas separation. PU was synthesized by two step polymerization based on isophorone diisocyanate (IPDI), 1,4-butanediamine (BDA), polytetramethylene glycol (PTMG) in the mole ratio of 3:2:1. The prepared blend membranes were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray Diffraction (XRD), and scanning electron microscopy (SEM). The effects of molecular weight of PVA, and blend composition on the gas transport properties of N2, O2, CO2 and CH4 were investigated. Obtained results show that the permeability of gases decreased in blend membranes by poly(vinyl alcohol) (PVA) molecular weights while their gas selectivity enhanced. Comparison of the gas separation performance of the prepared membranes to Robeson upper bound, reveal the enhancement of membrane performance by introducing PVA in PU matrix.

The development of thin film composite (TFC) membranes offers an opportunity to achieve the permeability/selectivity requirements for optimum CO2 separation performance. However, the durability and performance of thin film gas separation membranes are mostly challenged by weak mechanical properties and high CO2 plasticization. Here, we designed new polyurethane (PU) structures with bulky aromatic chain extenders that afford preferred mechanical properties for ultra-thin-film formation. An improvement of about 1500% in Young’s modulus and 600% in hardness was observed for pentiptycene-based PUs compared to the typical PU membranes. Single (CO2, H2, CH4, and N2) and mixed (CO2/N2 and CO2/CH4) gas permeability tests were performed on the PU membranes. The resulting TFC membranes showed a high CO2 permeance up to 1400 GPU (10–6 cm3(STP) cm–2 s–1 cmHg–1) and the CO2/N2 and CO2/H2 selectivities of about 22 and 2.1, respectively. The enhanced mechanical properties of pentiptycene-based PUs result in high-perform...

The aim of this study was to prepare stable waterborne epoxy emulsions and study the properties of their corresponding coatings containing different contents of silica nanoparticles. For this purpose and in the first step, the stabilizing effect of various amounts of an acrylate terpolymer latex (poly (methyl methacrylate-co-butyl acrylate-co-acrylic acid)) and a non-ionic emulsifier (nonyl phenol ethoxylates 20 emulsifier (known as Kenon 20)) on waterborne epoxy emulsions was explored. The results indicated that the emulsion containing 5 wt.% latex and 6 wt.% Kenon 20 (EK6A5) was the most stable. In the next step, silica nanoparticles with 1, 2, 3, and 4 wt.% were added to EK6A5 emulsion. It was found that addition of nanoparticles up to 3 wt.% improved the stability. Finally, the pure and nanoparticle contained emulsions were coated on a steel substrate and their adhesion performance, pencil hardness, surface wettability, and wear and corrosion resistance were investigated. The comparison between the samples with and without silica nanoparticles revealed enhanced properties such as adhesion strength (up to 5B), wear resistance, corrosion resistance (degree of blistering up to 8 F and mean rust creepage up to 10), and increased contact angle (up to 63°), by addition of proper amounts of silica nanoparticles (up to 3 wt.%).

Poly (ethylene glycol) (PEG)-based polyurethane (PU) membranes are attractive materials for CO 2 separation from various sources such as flue gas and syngas. However, the strong tendency of PEG chains to crystallize leads to reduced permeability of the membrane. Here, we developed new types of PU chemistries with high PEG content and reduced crystallinity. A series of PUs were synthesized based on mixtures of PEG and poly (propylene glycol) (PPG), and various PEG-PPG triblock copolymers (PEG-b-PPG). The presence of PEG-b-PPG triblock copolymers combines the high selectivity of PEG while the PPG pendant methyl group hinders local crystallization. The resulting membranes showed CO 2 permeability of 144 barrer and high CO 2 /N 2 and CO 2 /H 2 selectivities up to 54 and 8.3, respectively. Due to the absence of the crystalline soft phase, synthesized PUs with PEG-b-PPG triblock copolymers exhibit higher chain flexibility which is reflected by a decrease in the glass transition temperature of the soft segments. In contrast, the mixture of PEG and PPG showed minimal effects on the crystallinity of PEG domains. This resulted in lower membrane gas separation performance where CO 2 permeability and CO 2 /H 2 selectivity decreased to 68 barrer and 4.9, respectively.

In this study, the effect of calcium carbonate (CaCO3) nanoparticles on the barrier properties and biodegradability of polylactic acid (PLA) was investigated. For this purpose, nanocomposite films with various CaCO3 nanoparticle contents (0, 3, 5, 10, and 15 wt%) were prepared by solution casting method. The gas permeability of nitrogen (N2), oxygen (O2), and carbon dioxide (CO2) was evaluated through a constant volume and variable pressure apparatus at different pressures and temperatures. According to results, barrier properties were improved by loading CaCO3 nanoparticles up to 5 wt%, and the gas permeability of CO2, O2, and N2 was decreased from 1.4, 0.31, and 0.07 Barrer to 0.48, 0.095, and 0.019 Barrer, respectively. In addition, it was also observed that the gas permeability of samples was decreased by increasing feeding pressure and increased by enhancing temperature. Furthermore, morphological results confirmed the formation of agglomerations and large clusters over 5 wt% CaCO3 nanoparticles. Finally, the thermal properties and biodegradability of PLA were increased by employing CaCO3 nanoparticles. These results suggested PLA nanocomposites as favorable candidates for food packaging applications.

This study involves the preparation and characterization of polyurethane (PU) and polyurethane/poly(ether-block-amide) (PU/PEBA) blend membranes for gas separation. Polyurethane was synthesized by two-step polymerization based on isophorone diisocyanate (IPDI), polytetramethylene glycol (PTMG2000), 1,4-butanediamine (BDA) and 1,4-butanediol (BDO) in mole ratios of 3:1:2. Two kinds of PEBA, MV3000 and MH1657, were chosen to prepare PU/PEBA blend membranes. The effects of the blend composition on the permeability of N2, O2, CO2 and CH4 were investigated. All membranes were prepared by thermal phase inversion. Physical properties of synthesized polyurethane and prepared blend membranes were investigated by FT-IR, XRD and SEM analyses. FT-IR results indicate that phase separation of hard and soft segments decreased as the amount of PEBA in blend membranes increased. XRD results demonstrate that crystallinity rose by increasing the amount of PEBA in the blends. According to the SEM micrographs of the prepared samples, PU/PEBA blend membranes are miscible systems. The results of gas permeation experiments demonstrate that by increasing the amount of PEBA in PU/PEBA blend membranes, the permeability of all gases decreased while selectivity increased.

In this study, the effects of silica nanoparticles on the permeability of pure CO2, O2, and N2 gases in cellulose acetate (CA) membrane have been studied. Silica particles were prepared via the sol–gel method through the hydrolysis of tetraethyl orthosilicate (TEOS). CA and CA/silica nanocomposite membranes were prepared by thermal phase inversion method. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and Fourier transfer infrared (FTIR) analyses were employed to characterize the CA and CA/silica nanocomposite membranes. Gas permeation experiments showed an increase in the permeability of CO2 from 6.32 to 7.3 barrer and a reduction in the permeability of N2 from 0.18 to 0.09 barrer with the increment in silica content of the prepared composite membranes up to 20 wt%. Therefore, CO2/N2 selectivity of the nanocomposite membranes increased by increasing the silica content in the polymer matrix from 30 to 80 for 20 wt% load of silica.

In the present study, the effect of the addition of electrically conductive additives such as graphite, graphene, and high structure nano-carbon black on the manufacturing of polypropylene bipolar plates was studied. Furthermore, for achieving better dispersion of graphene in the matrix, maleic anhydride grafted polypropylene, as a compatibilizer, was utilized. An internal mixing device was used in order to mix additives with polypropylene matrix. Additionally, molding procedure was performed via the compression molding method. In-plane electrical conductivity as well as the flexural strength of various compositions were studied. The best composition of such composites possessed the electrical conductivity of 104.63 S/cm and flexural strength of 44.28 MPa. These values are higher than those designated by the United States Department of Energy for construction of bipolar plates.

In this study, we report highly selective CO 2 polyurethane incorporated with cured epoxy nanoparticles. PU–epoxy composite membranes were prepared via solution casting method. The obtained SEM micrographs confirmed the nano-scale distribution of epoxy particles in the polymer matrix. DSC and FTIR spectra showed different phase separation for the PU composites compared to the pure PU. The effect of epoxy nanoparticles on the gas permeability of CO 2 , CH 4 , O 2 and N 2 was studied at 25 °C and 10 bar. The selectivity of CO 2 /N 2 increased from 25 for the pure PU membrane to 55.5 for the PU–EP10, while the CO 2 permeability was unchanged.

Polymer blending and mixed-matrix membranes are well-known modification techniques for tuning the gas separation properties of polymer membranes. Here, we studied the gas separation performance of mixed-matrix membranes (MMMs) based on the polyurethane/poly(vinyl alcohol) (PU/PVA) blend containing silica nanoparticles. Pure (CO2, CH4, N2, O2) and mixed-gas (CO2/N2 and CO2/CH4) permeability experiments were carried out at 10 bar and 35 &deg, C. Poly(vinyl alcohol) (PVA) with a molecular weight of 200 kDa (PVA200) was blended with polyurethane (PU) to increase the CO2 solubility, while the addition of silica particles to the PU/PVA blend membranes augmented the CO2 separation performance. The SEM images of the membranes showed that the miscibility of the blend improved by increasing the PVA contents. The membrane containing 10 wt % of PVA200 (PU/PVA200&ndash, 10) exhibited the highest CO2/N2~32.6 and CO2/CH4~9.5 selectivities among other blend compositions, which increased to 45.1 and 15.2 by incorporating 20 wt % nano-silica particles.

Polyurethanes (PUs) and polyurethane-ureas (PUUs), with good mechanical stability and the possibility of tuning the gas transport properties are promising materials for selective gas separation membranes. Here, we synthesized various types of PUs and PUUs with polytetramethylene glycol (PTMG), isophorone diisocyanate (IPDI) and different ethereal chain extenders (1:3:2 M ratio). FTIR and DSC results showed that the phase separation would vary in PUs and PUUs structures by changing the length and functionality of the chain extenders. More mixing was inferred for PUs and PUUs with high ethereal content. In contrast, phase separation was more likely with increases in the chain extender length. Pure (CO2, CH4, O2 and N2) and mixed gas (CO2:N2 (50:50 vol%) and CO2:CH4 (50:50 vol%)) permeation measurements correlated well with the phase separation in the polymer structure. The octanediamine-based PUU with the highest amount of phase separation showed the highest permeability (160 barrer for CO2 and CO2/N2 selectivity of 30). On the other hand, the 3,6-dioxa- 1,8-octanediol- based PU, despite having the same chain extender length as octanediamine-based PUU, presented the lowest phase separation and gas permeability (62 barrer for CO2 and CO2/N2 selectivity of 29).

The effect of zeolite 3A, 4A, and ZSM-5 on the gas separation performance of polyurethane (PU)–zeolite mixed matrix membranes (MMMs) has been investigated in this study. Permeation of pure CO2, CH4, N2, and O2 gases through PU–zeolite MMMs with zeolite content of 6, 12, 18, and 24 wt% was studied. The prepared hybrid membranes were characterized using Fourier transform infrared spectroscopy and scanning electron microscope. Membrane characterization confirmed the homogeneous distribution of zeolite particles at low zeolite loadings in the prepared membranes. The obtained results confirmed a significant enhancement in the permeability of all gases and the CO2/N2, CO2/CH4, and O2/N2 selectivities by increasing the content of zeolite particles in PU–zeolite MMMs. The PU–zeolite 4A with 12 wt% zeolite loading showed the best performance in terms of gas permeability and selectivity for CO2/N2, CO2/CH4 and O2/N2 gas pairs.

Polyurethanes (PUs) with good film formation ability and high gas separation properties are promising materials for gas separation membranes. However, low mechanical properties and high CO2 plasticization limit the industrial application of these membranes. Here, we synthesized a crosslinkable PU structure using a 1 : 3 : 2 molar ratio of Pluronic L61, isophorone diisocyanate (IPDI) and 3,5-diaminobenzoic acid (DABA). In order to improve both mechanical properties and plasticization resistance, a series of crosslinking agents with different chain lengths and functionalities were used to crosslink the PU via an esterification-based reaction. Pure (H2, CO2, N2, CH4, and C2H6) and mixed (CO2/N2 and CO2/CH4) gas permeability experiments were performed on the crosslinked PU (XPU) membranes. The XPU membranes showed enhanced mechanical properties and chemical stability and improved plasticization resistance to an extent about three times higher than the non-crosslinked PU and commercial membranes (PEBAX® 2533). Mechanical tests indicated an improvement of over 600% in Young's modulus and 200% in hardness for XPUs compared to the pristine PU. The resulting crosslinked membranes with high CO2 separation performance (CO2/N2 ∼ 30) and superior thermal and mechanical properties are attractive candidates for industrial separation processes.

Novel poly(urethane-urea) (PUU) membranes were developed as the aim of a structure-property relationship study to enhance gas permeation. Designing the PUUs was followed by three synthesized chain extenders with different length-alkyl side chains, polytetramethylene glycol, and isophorone and hexamethylene diisocyanates. The longest substituted PUU indicated higher phase separation and lower glass transition temperature. Pure and mixed gas permeabilities of prepared membranes grew as phase separation of PUU material increased, while fractional free volume decreased by lengthening the side chain of the PUUs. The reasons for this event were the migration of the side chains to the surface of hard domain, thereby shielding it and filling the soft/hard interface. Enhanced permeability of materials with l onger side chains is attributed to its plasticizing effect. The highest CO2 permeability (287 barrer) was obtained for the longest substituted PUU. The findings revealed an increase in gas permeation without a significant reduction of selectivity by longer substituted PUUs.

Poly(ether sulfone) (PES)/poly(vinyl pyrrolidone) (PVP) blend heterogeneous cation exchange membranes were prepared by solution casting technique using dimethylformamide as solvent and cation exchange resin powder as functional groups agent. In this study, Taguchi experiment design method was employed for investigating the effects of controlling variables including polymer binder (PVP + PES) to total casting solution ratio, blend ratio of polymer binders (PVP to PES), resin to polymer binder ratio, and casting temperature on electrochemical characteristics of PES/PVP heterogeneous membranes. To this aim, each factor was considered at 4 different levels and therefore, 16 experiments were designed. To improve the quality of the membranes ultrasonic was used for appropriate dispersing of resin particles in the matrix of the membranes. According to the results, the averaged maximum values of 1.535 meq/g and 46.6 mV were obtained for IEC and membrane potential, respectively. Also, the highest obtained value of ion permeability tests was equal to 1.33 m/s. Finally, the synthesis conditions was optimized by considering the IEC and membrane potential as the objective functions which gave the values of 1.55 meq/g and 1.39 m/s for IEC and membrane potential, respectively, which proved that the synthesized membrane can be considered as a promising heterogeneous membrane.

In this study, a new approach to improve antifouling performance of polyacrylonitrile (PAN) hollow fiber membrane has been explained. Firstly, chemical modification with sodium hydroxide (NaOH) solution was performed on PAN membranes in various conditions, so that, as a result of hydrolysis, carboxyl groups emerge on membrane surface. Then, in order to improve surface hydrophilicity, the hydrolyzed membrane underwent a polyethylene glycol (PEG) deposition through a chemical reaction. Chemical changes in membrane were characterized via Fourier transform infrared spectroscopy/attenuated total reflectance (FTIR/ATR). In addition, measurement of contact angle and fouling test were performed to analyze hydrophilicity degree and performance of modified membrane, respectively. Results of measuring contact angle signified improvement of hydrophilicity of membrane after modification. Modified membranes showed lower tendency to foul during ultrafiltration (UF) of milk solution, which is confirmed by increase in flux recovery ratio (FRR) level following membrane modification. Three hours after hydrolysis process, though pure water flux through membrane reduced by 28% comparing with intact membrane, the level of polyvinyl alcohol (PVA-30 kDa) rejection and FRR increased 13 and 14%, respectively. Upon attachment of PEG to the membrane surface, the contact angle reduced from 64° for non-modified membrane to 21°.

Improvement of biogas production by pretreatment of rice straw with 0.25 and 0.5 M sodium carbonate at 90, 110, and 130 °C and for 1, 2, and 3 h was investigated, and promising results were obtained. All treated and untreated rice straws were digested under mesophilic conditions (37 °C). Increasing the concentration of sodium carbonate showed significant improving effects, whereas the treatment time showed less impact. The best results, obtained by pretreatment with 0.5 M sodium carbonate at 110 °C for 2 h, resulted in the production of 292 mL of CH4 per gram of VS, whereas untreated rice straw produced 130 mL of CH4 per gram of VS. Compositional, SEM, and FTIR analyses confirmed that structural modification, lignin removal, and cellulose crystalline reduction are responsible for the improvement.

In this work, polyurethane (PU) nanocomposite membranes were prepared using different concentrations of alumina (Al2O3) nanoparticles (0, 2.5, 5, 10, 20, and 30 wt%). The main objective of this work is to evaluate the permeability of CO2, CH4, O2, and N2 gases in the polyurethane hybrid membranes at various Al2O3 contents and with two different chain extenders. Polyurethane was synthesized by bulk two-step polymerization based on polytetramethylene glycol (PTMG) and hexamethylene diisocyanate (HMDI). 1,4-butanediol (BDO) and 2-methyl-1,3-propanediol (MPD) were used as chain extenders to complete the conversion of the prepolymers to the final polyurethanes. The prepared polyurethane–Al2O3 membranes were characterized using Fourier Attenuated Total Reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, scanning electron microscope (SEM), wide angle X-ray diffraction (WAXD), and differential scanning calorimetry (DSC) analyses. The results show a reduction in the gas permeability, but a significant enhancement in the CO2/N2, CO2/CH4, and O2/N2 selectivities with alumina content. The separation performances of the membranes were compared with Robeson׳s upper bound limit. The new modified Higuchi model was applied to predict the permeability of polyurethane–alumina hybrid membranes.

In this study, a new method was applied to achieve an efficient surface modification of Polyacrylonitrile (PAN) hollow fiber membrane. The surface modification dealt by immersion of PAN hollow fibers in hydroxylamine solution under various conditions (different solution concentrations and reaction time). The nitrile groups on the surface of the membrane were changed to form the amidoxime (-C(NH2)=N-OH) groups. The surface modified membranes were assessed by pure water permeation test and the rejection of high molecular weight materials like Polyvinylalcohol (PVA) from water. Permeation test results showed that with increasing hydroxylamine concentration, the amount of water permeation reduces slowly, while the PVA-30 kDa rejection has been somewhat increased after surface modification. FTIR/ATR analysis confirms the presence of amidoxime groups on the membrane surface. Also, the water contact angel was decreased from 64 to 34 after reaction. The ability of silver ions absorption was also assessed for modified membrane. Finally, the antifouling property of the modified hollow fibers was assessed by milk solution ultrafiltration. The obtained results showed that the modified hollow fibers present better antifouling properties.

In this research, the effects of Zeolite 4A and ZSM-5 on the separation of C2H6 and C3H8 from CH4 through polyurethane/zeolite mixed matrix membranes (MMM) are evaluated. Physical properties of synthesized polyurethane and polyurethane/zeolite MMM were investigated by FTIR, XRD, TGA and SEM analyses. Results indicate that phase separation of hard and soft segments in polyurethane would be increased by adding butanediamine (BDA) chain extender in polymer due to the generation of more hydrogen bonds between hard segment domains. The obtained SEM micrographs confirm that the Zeolite is distributed in the polymer matrix homogenously. The results of gas permeation represent that permeability and selectivity of Hydrocarbons are increased by increasing the urea groups in the polymer structure. Moreover, the obtained results of gas permeation of polyurethane–zeolite (4A) membranes indicate an increase in the permeability of Methane, with the reduction in C2H6/CH4 and C3H8/CH4 selectivity by increasing the Zeolite 4A up to 10 wt%. In addition, the results of the gas permeation of polyurethane–zeolite (ZSM-5) MMM indicate a significant increment in permeability and selectivity of all Hydrocarbons. The permeability of Propane and its selectivity over Methane is increased from 64.8 Barrer and 2.6 into 117.2 Barrer and 3.64 in with 20 wt% filled PU–ZSM 5 MMM, respectively.

The effect of TiO2 nanoparticles on the gas separation properties of polyurethane has been investigated. Polyurethane was synthesized using hexamethylene diisocyanate (HDI) and 1,4-butanediol (BDO) as hard segment and poly(tetramethylene glycol) (PTMG, 2,000 g/mol) as soft segment. The synthesized polymer was in a 1: 2: 1 molar ratio of polyol:diisocyanate:chain extender through bulk two-step polymerization. PU membranes were prepared by thermal phase inversion method. Scanning electron microscopy (SEM), X-ray diffraction and Fourier Transform Infrared (FTIR) analyses characterized the prepared membranes. FTIR and SEM results indicate the good interaction between particles and polymer matrix and also the nanoscale dispersion of TiO2 particles in polymer matrix. Gas permeation properties of PU-TiO2 nanocomposite membranes with TiO2 contents up to 30 wt% were studied for N2, O2, CH4 and CO2 gases at 10 bar and 25 °C. Results suggest a decrease in permeability of studied gases and increase in gas selectivities as TiO2 content increases.

In this research, the capability of ultrafiltration hollow fiber polyvinylidene fluoride membrane by polyaluminum chloride in pretreated oil-in-water emulsion was studied. Central composite design and response surface method were applied to optimize the operating variables: transmembrane pressure (TMP) and velocity. Quadratic models developed for the three responses (permeate flux (PF), turbidity removal, and chemical oxygen demand (COD) removal) indicated that the optimum PF of 50 L/m2 h, turbidity removal of 79%, and COD removal of 77% would be achieved after pretreatment at a TMP of 1 bar and velocity of 3 m/s. The simulated values obtained from the statistical model were in agreement with the experimental results.

This study examines the role that silica nanoparticles play on the permeation of methane, ethane, and propane gases through two types of polyurethane (PU) membranes: one based on polyether and the other based on polyester. These PU membranes are synthesized from polycaprolactone (PCL225) polyester and polypropylene glycol (PPG) polyether in a 1–3–2 mol ratio of polyol/hexamethylenediisocyanate/1,4-butane diol. The prepared PU-silica membranes are characterized using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and wide-angle X-ray diffraction (WAXD) analyses. The characterization analyses confirmed the nanoscale distribution of silica particles within the polymer matrix. Permeation experiments reveal that in polyether-based PU, permeability first increases by increasing silica content up to 2.5%, and then decreases. The permeability of gases in polyester-based PU constantly decreases by increa...