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This study deals with the fabrication of hollow fiber mixed matrix membrane, and evaluation its performance toward O2/N2 gas separation. Asymmetric mixed matrix PES membranes with embedded ZIF-8 nanoparticles as the dispersed phase were prepared by dry–wet-spinning method. The morphological, thermal, and chemical properties of spun fibers were characterized by FESEM, EDS mapping, TGA, and FTIR analysis. Effect of spinning parameters and dope composition including bore fluid/ dope flow rate ratio (0.5, 1, 2), bore fluid composition (Water/NMP: 100:0, 50:50, 75:25), polymer concentration (20%, 25%, 30%), and ZIF-8 concentration (0–40%wt at seven stages) were investigated on the morphology of hollow fiber MMMs. In addition, pure O2 and N2 gas permeation through the fibers was tested in order to figure out the effect of different ZIF-8 content embedded in hollow fiber MMMs on the ideal selectivity of O2/N2 separation. Results revealed that the maximum separation performance (ideal selectivity of 5.25) was attained at the ZIF-8 weight content of 10%. The improved performance of hollow fiber MMMs over O2/N2 gas separation could be related to increment in both sieving and solubility selectivity.

In this research, the membrane separation process was used to separate helium from methane gas. In order to do this, computational fluid dynamics (CFD) was used, and the effect of process parameters on the performance of the membrane separation process was studied by this method. To simulate the hydrodynamics of flow in the channel, the Navier-Stokes equation was used, and the Maxwell-Stefan equation was applied to simulate the mass transfer phenomenon. In addition, Fick’s law was utilized to simulate mass transfer in the membrane domain. The impacts of significant parameters such as feed pressure, feed flow rate, and feed concentration on parameters such as He/CH4 separation factor, methane and helium membrane flux and helium mole fraction in permeate stream were studied. The results of the simulation indicated that the feed pressure of 10 bar, feed flow rate of 120 cm3 min–1, and feed mole fraction of 0.0254 had the best membrane performance in He/CH4 separation. This work is licensed under a Creative Commons Attribution 4.0 International License.

Due to the momentum and energy exchange between the gas and solid surface molecules, by means of the accommodation coefficients in the Cercignani-Lampis-Lord (CLL) model, the velocity components used in the Direct Simulation Monte Carlo (DSMC) method can be studied more accurately. The coefficients can also be used in calculation of slip velocity, temperature jumping, drag force and shear stress. In the light of rising needs for polymers in industrial applications, the scattering behavior of noble gas molecules in their collision with a surface made of diglycidyl ether bisphenol A (DGEBA) epoxy resin, cured by tetrahydrophthalic anhydride (THPA) agent and reinforced by multi-layer graphite, was simulated and investigated by Molecular Dynamics (MD). The momentum and energy accommodation coefficients for gas–surface interactions were also calculated by MD simulation. The results indicated that temperature increase, change in the gas species, reduction in surface roughness, and increase in the Knudsen number ( Kn ) and the wall velocity could cause the accommodation coefficients to be less than one. Based on the scattering kernel of CLL boundary condition, a suitable distribution function for calculating the velocity components of noble gas molecules (e.g., argon molecules) after interaction with polymeric surface was proposed.

In this article, numerical simulations are performed to investigate the performance of the thermal diffusion column for the separation of n-heptane/benzene mixture. The present work tried to optimize column by analyzing significant parameters such as feed flow rate, temperature and cut. In order to obtain the hydrodynamic and temperature and mass distribution inside thermal diffusion column, computational fluid dynamic (CFD) method is applied to solve the Navier–Stocks equations. Numerical simulations are conducted to study the main parameters in both stationary and time-dependent conditions. By using the separation work unit as a function of cut, the optimal cut for maximum SWU occurs within a limited range of 0.47–0.5 for feed rate between 0.5 and 4 g·min−1. Our findings reveal that the optimum feed rate in the range of optimum cut is about 1 g·min−1. In transient study, results show that the best cut for reaching to steady-state condition is θ = 0.5.

In this study, composite membranes were fabricated through embedment of hexagonal boron nitride (h-BN) in the polyvinylidene fluoride (PVDF). Exfoliated h-BN nanosheets were characterized by transmission electron microscope (TEM). Then, different concentrations of h-BN were incorporated into PVDF to explore their impacts on the membrane performance. Various analyses comprising Fourier transform-infrared spectroscopy (FT-IR), energy dispersive X-ray (EDS), scanning electron microscopy (SEM), and atomic force microscopy (AFM) were applied to identify the membrane characteristics. The composite membrane properties including thermal and mechanical stability, liquid entry pressure (LEP), hydrophobicity, flux, and salt rejection were also investigated. Results showed that PVDF/h-BN membranes compared with PVDF had higher roughness, hydrophobicity, flux, and salt rejection. Applying operating temperature at 80 °C, M2 (contained 0.5 wt% h-BN) as the best membrane indicated flux of 7.1 kg/m2·h (43% increase compared to PVDF) and 99% salt rejection during 60 h continuous desalination process. These improvements in desalination performance were due to increase in pore size, porosity, and van-der-waals interactions between water and h-BN atoms that facilitated fast transport of water through membrane. Moreover, polar nature of B N bonds in h-BN induced high affinity with water that contributed to the selective separation of water through passing from the h-BN nanochannels.

Using microfluidic systems in liquid-liquid extraction process has distinctive advantageous, including lower consumption and high extraction efficiency. In this research, the separation of calcium metal ions from the aqueous phase is investigated by use of 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIM NTf2) and 1-Butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMIM NTf2) to enhance the performance of the liquid-liquid extraction. The main idea is to evaluate the geometrical effect of microchannel in the extraction efficiency. For this purpose, the spiral microchannel was constructed to induce the centrifugal force. Comprehensive parametric studies are done to reveal the effect of the main parameters on the extraction performance of the microfluidic device. At first, the effect of the alkyl chain of ionic liquids in the extraction efficiency is investigated. The results showed that the shorter length of the chain has the higher extraction efficiency. Then, the physical parameters such as calcium concentration, a crown ether concentration and the pH are optimized in the traditional extraction. The results of experiments show that the maximum extraction efficiency of 50% is achieved when the concentrations of calcium and crown ether are 75 ppm and 3.75 mM, respectively, and the pH value of aqueous phase is 7. In the final step, the microfluidic system was used to study the hydrodynamic parameters influencing on the mass transfer. These parameters are: different geometries of microchannel (spiral and Y-shaped), and different flow rates of aqueous phase and the ionic liquid in the droplet flow pattern. Our findings reveal that the spiral microchannel is more efficient when the flow rate of water and the ionic liquid phases is highest and extraction efficiency of 52% is obtained in this condition, which is equivalent to equilibrium extraction efficiency.

In this study, pure Cu-BDC and composite Cu-BDC@rGO were produced by combining microwave irradiation and microfluidics (MW-assisted microfluidic) to intensify the hydrogen adsorption. To compare two heating methods, pure Cu-BDC was synthesized by both MW-assisted microfluidic and conventional heating methods. Results showed that the production yield and hydrogen adsorption capacity of Cu-BDC was 18% and 26% greater for MW-assisted microfluidic heating, respectively. In addition to the results, this method brings some advantageous such as lower reaction time, lower reactor size, more uniform crystal shape, and lower crystal size compared to conventional heating. So, the MW-assisted microfluidic method was selected for further investigations. Response surface method (RSM) applied to find the optimum synthesis condition of the material for hydrogen uptake. In this regard, GO content, metal/linker molar ratio, and microwave (MW) time selected as independent, and the hydrogen adsorption at 77 K and 40 bar selected as the dependent response. Also, experiments showed that the one pot synthesis of Cu-BDC@rGO (sandwich-like adsorbent) has the best hydrogen uptake compared to pure Cu-BDC (cubic adsorbent) and the other sample (worm-like adsorbent) which is confirmed the effect of modulating synthesis route. Finally, it must be said that the incorporation of GO and MW-assisted microfluidic heating improved the specific surface area, pore volume, throughput, and thermal stability of the adsorbent.

Gold nanoparticles (GNPs) have generated keen interest among researchers in recent years due to their excellent physicochemical properties. In general, GNPs are biocompatible, amenable to desired functionalization, non-corroding, and exhibit size and shape dependent optical and electronic properties. These excellent properties of GNPs exhibit their tremendous potential for use in diverse biomedical applications. Herein, we have evaluated the recent advancements of GNPs to highlight their exceptional potential in the biomedical field. Special focus has been given to emerging biomedical applications including bio-imaging, site specific drug/gene delivery, nano-sensing, diagnostics, photon induced therapeutics, and theranostics. We have also elaborated on the basics, presented a historical preview, and discussed the synthesis strategies, functionalization methods, stabilization techniques, and key properties of GNPs. Lastly, we have concluded this article with key findings and unaddressed challenges. Overall, this review is a complete package to understand the importance and achievements of GNPs in the biomedical field.

Flow patterns of six liquid–liquid systems in a numbered-up microfluidic set-up were studied in this work. Chloroform-water, butyl acetate-water, ethyl acetate-water, kerosene-water, butanol-water and octanol–water were chosen as test liquids. Three distinct flow regimes were observed in the parallelized microfluidic device: slug flow, droplet flow and parallel flow. A uniform flow distribution was achieved in the scaled-out microfluidic device for all observed flow regimes. Flow non-uniformity was determined based on both the volumetric flow rate and slug size/droplet size/interface position for each microchannel. The two-phase interface's position relative to the microchannel walls was considered a criterion for flow non-uniformity measurement in parallel flow. A comprehensive dimensionless analysis was also performed to determine which dimensionless numbers are appropriate for presenting universal flow maps. R e - 0.31 W e 0.41 , W e 0.07 C a 0.31 , R e 0.07 C a 0.41 , C a 0.5 O h - 0.14 , W e 0.25 O h 0.31 and R e 0.5 O h 0.82 were identified as the suitable combinations of dimensionless numbers for proposing generalized flow pattern maps for the numbered-up set-up. For the slug and droplet flow regimes, slug and droplet length and velocity were also investigated.

Experimental and numerical studies were conducted on the mass transfer efficiency of new wire gauze structured packing. For serving this purpose, various operational conditions were studied...

RSM methodology was applied to present mathematical models for the fabrication of polyvinylidene fluoride (PVDF) dual-layer hollow fibers in membrane distillation process. The design of experiments was used to investigate three main parameters in terms of polymer concentration in both outer and inner layers and the flow rate of dope solutions by the Box-Behnken method. According to obtained results, the optimization was done to present the proper membrane with desirable properties. The characteristics of the optimized membrane (named HF-O) suggested by the Box-Behnken (at the predicted point) showed that the proposed models are strongly valid. Then, a morphology study was done to modify the fiber by a combination of three types of a structure such as macro-void, sponge-like and sharp finger-like. It also improved the hydrophobicity of outer surface from 87 to 113° and the mean pore size of the inner surface from 108.12 to 560.14 nm. The DCMD flux of modified fiber (named HF-M) enhanced 62% more than HF-O when it was fabricated by considering both of RSM and morphology study results. Finally, HF-M was conducted for long-term desalination process up to 100 hr and showed stable flux and wetting resistance during the test. These stepwise approaches are proposed to easily predict the main properties of PVDF dual-layer hollow fibers by valid models and to effectively modify its structure.

In this study, novel membranes are designed and fabricated using CTA as the main matrix with contributions of PEG and as-synthesized ZIF-8 nanoparticles. Gas permeation properties of blend membranes containing 25–45 wt.% PEG and MMMs containing 2–20 wt.% ZIF-8 crystals are evaluated for the separation of He from N2 and CH4 at various temperatures and pressures. The properties of synthesized ZIF-8 nanoparticles as well as membranes are well characterized. Among all the prepared membranes, the MMMs membrane with composition of CTA/PEG/ZIF-8 (60/20/20 wt.%) exhibits the best performance (PH2 = 73.25 Barrer) for He/N2 (α = 43) and He/CH4 (α = 40) separations. In addition, various predictive permeation models are investigated in order to gain more insights about the systems and for validation of the experimental results. The %AAREs of the models are high, while the best value is obtained by applying the Maxwell model (5.98). Also, by choosing Lewis–Nielsen model and taking into account some of the non-ideal effects such as particle pore blockage, polymer chains rigidification as well as the effect of particles size on the rigidified layer thickness, a new while accurate model is proposed. Finally, the accuracy of the newly developed model is examined utilizing several experimental data.

In this study, life cycle assessment of oxygen-18 by using cryogenic distillation of oxygen is performed using SimaPro 8.3 software. Life cycle assessment is performed to understand the environmental profile and hotspots of this process in order to be used in design and development. Simulation of oxygen-18 process is executed by Hysys software, and the required inputs and outputs for inventory of life cycle were acquired. By doing life cycle assessment and considering achieved results after characterization and normalization of inventory data it has been investigated that in the majority of environmental impacts electricity consumption has a huge contribution relative to other parts of the system like liquefied oxygen production from air separation unit, required facilities for air separation and oxygen-18 units, and needed transportation. Also, among 17 impact categories investigated in ReCiPe impact assessment method, fossil depletion, climate change (human health), particulate matter formation, climate change (ecosystem), human toxicity, and metal depletion have the most contribution in entire environmental loads respectively. Furthermore, sensitivity analysis showed that changing life cycle impact assessment method from ReCiPe to IMPACT 2002 + has no significant effect on acquired results and results are confident. In addition, assumption of market for depleted oxygen from heavy isotopes which is withdrawn from top of distillation columns showed some positive effects compared to first case and environmental impacts resulted from liquefied oxygen production (feed) reduced but because of huge contribution of electricity consumption compared to other sections, this positive effect has no remarkable influence on entire environmental loads of product system.

The preparation and characterization of a novel type of castor oil-based polymer inclusion membrane (PIM) was investigated, focusing on its flux and selective recovery of Ca2+ over competitive ions such as K+, Na+, and Mg2+. The PIM contains a cross-linked high-molecular-weight green polyol (GPO) as a polymer base, benzene-18-crown-6 as a carrier, and an ionic liquid called 1-Butyl-3-methylimidazolium chloride as a plasticizer. GPO was first synthesized by a reaction between an epoxidized castor oil and a cellulose acetate, thereafter, cross-linked by isophorene isocyanate. The base polymer and the prepared PIM were characterized by gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), atomic force microscopy (AFM), thermogravimetric analysis (TGA), and X-ray diffraction (XRD). The FTIR results indicate that oxirane groups in the epoxidized castor oil molecules reacted with the primary hydroxyl groups of cellulose acetate chains. The contact angle measurement hints at the hydrophobic characteristics of the prepared membrane. Compared to the PVC-, CA-, and PVDF-based polymer inclusion membrane, the cured GPO-based PIM, showed higher selectivity and flux of calcium ions with the same composition. The greater stability and significantly higher surface roughness are further favorable features of the novel PIM.

A simple non-equilibrium modeling approach is proposed to simulate multicomponent distillation process in packed columns. The real behavior of the column is simply considered by the evaluation of interphase mass transfer rate based on the overall mass transfer coefficient. Two distinct methods are used to calculate this overall coefficient including the effective mass transfer coefficient method and the packing efficiency method. The modelling procedure consists of an iterative segment-wise algorithm implemented in a MATLAB home-code. For verification, the obtained composition profiles from a structured and a random packed column are compared with reported experimental data. Comparisons show that the packing efficiency-based model could acceptably predict the experimental profiles with an average relative deviation of 18% and 25% for structured and random packed columns, respectively. This confirms that our simple non-equilibrium approach is a reliable and robust model for the performance evaluation of packed columns.

Graphene oxide membranes were prepared by vacuum and pressurized ultrafiltration methods on the 12% modified Polyacrylonitrile (12mPAN) substrate to specify challenges, salient features, future directions, and potential of GO membrane for separation fields using characterization techniques and gas separation test (studied gases are CO2, He and N2), which is an efficient tool for better understanding of GO membrane behavior. GO membrane structure was examined over a wide range of parameters, such as pore size range of substrate and its surface properties, pH of GO dispersion, GO content, synthesis pressure, operating pressure and temperature. The results show that the GO content does not hold a linear relationship with the permeance and selectivity. Film thickness, aggregates, synthesis pressure defects and interlayer spacing have significant effects on the gas separation performance of GO membranes which originate from the synthesis method and its conditions.

In this research, a continuous microsolvent extraction-reaction was developed for the efficient separation of calcium ion. This study gives a preliminary possible practical application of microfluidic devices in chemical exchange reaction for enrichment of 48Ca stable isotope. For this purpose, in the first stage, the hydrodynamic behavior of two immiscible liquids in a simple Y-shaped microfluidic junction is experimentally investigated, and then ion-pair extraction-reaction of Ca2+ using picric acid as a counter-ion and dicyclohexano-18-crown-6 (DC18C6) as a lipophilic ionophore is studied in this microfluidic and conventional batch method. The impact of main process parameters, including concentration of calcium chloride (0.001–0.1 M), picric acid (0.002–0.2 M), and DC18C6 (0.001–0.1 M) on the extraction-reaction efficiency and apparent overall volumetric mass transfer coefficient was comprehensively examined by utilizing response surface methodology (RSM), leading to an optimized condition for the separation of calcium. In addition, by changing the dimensions of microreactors, the influence of contact time and flow rates of both phases on the extraction-reaction efficiency was investigated. The results show that the efficiency varies significantly with changes in reagent concentration. Since the efficiency decreased with increasing the calcium chloride, the existence of a small amount of picric acid and DC18C6 in the organic phase facilitates the extraction-reaction. Moreover, the extraction-reaction is almost accomplished within ∼ 1.5 s with the efficiency of 98.55% by using the microfluidic device whereas the equilibrium condition is obtained in at least 30 min in a batch method. Furthermore, the higher contact time and flow rates result in the higher separation of the calcium ion.

In the present research, a novel dual-layer membrane was prepared by coating a very smooth layer of octadecylamine functionalized graphene oxide (GO-ODA) on the surface of polyvinylidene fluoride membrane. The GO and GO-ODA were characterized by XRD, TGA and FE-SEM and pure PVDF (unmodified) and dual-layer (modified) membranes were also characterized by contact angle, pore size distribution, liquid entry pressure (LEP), FT-IR, SEM, AFM, and ATR-FTIR. Modified membranes in comparison with unmodified membrane showed a superior performance in terms of surface roughness, hydrophobicity, water flux and NaCl rejection. In air gap membrane distillation (AGMD) experiments using a 3.5 wt% NaCl solution as feed at 80 °C, unmodified, M1 (low GO-ODA loading), and M2 (high GO-ODA loading) modified membranes showed water fluxes of 18.2, 13.8, and 16.7 kg/m2·h and salt rejections of 88.5%, 96.3%, and 98.3%, respectively. This improvement in membrane performance was attributed to the existence of GO-ODA on the top layer of modified membranes that formed interconnected nano-channels with high surface area for high NaCl rejection and fast flow of water. Furthermore, GO-ODA with high hydrophobicity and low thermal conductivity on the surface of modified membranes contributed to reduce pore wetting, temperature polarization and heat diffusion across the membrane.

In this paper, the comprehensive experimental examinations are conducted to investigate the mass transfer properties of Dixon ring packing. The main aspect of this study is to investigate the characteristics of Dixon ring packing using a narrow packed column. Firstly, the mass transfer properties of the packing were investigated using distillation experiments at total reflux. Afterwards, the pervasive experiments were conducted to plot the generalized pressure drop correlation chart. Finally, the variation of height equivalent to a theoretical plate (HETP) was determined at total reflux operations for various vapour loading factors. Our findings showed that increasing the vapour loading factor up to 0.62 Pa0.5 would eventually decrease the HETP. It was also shown that the further increase in the vapour loading factor results in a sudden increase in the HETP value. According to our findings, the selection of the optimum vapor loading factor would enhance the value of HETP up to more than 57 %.

A novel replaceable microreactor was designed to investigate the catalytic decomposition of nitrous oxide. The replaceable microchannel plate was coated using 1wt.% Pd/anodic γ-Al2O3. The anodization method was adopted to prepare the anodic γ-Al2O3 on the aluminum microchannel plate. Palladium was loaded on anodic γ-Al2O3 support by wet impregnation technique. The morphology, thickness, structure, reduction behavior, surface area, and the catalytic performance of the catalyst were characterized via field emission scanning electron microscope (FE-SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD), transmission electron microscopy (TEM), H2 temperature-programmed reduction (H2-TPR) and Brunauer-Emmett-Teller (BET) surface area analysis. The performance of the prepared catalyst into the replaceable microreactor was experimentally investigated through nitrous oxide decomposition reaction in the temperature range of 280-340 °C and various GHSV of 1000, 2000, and 3000 mL h−1 gcat−1. Complete conversion of N2O decomposition was achieved at the temperature of 340 ∘ C , atmospheric pressure, and a GHSV of 1000 mL h−1gcat−1. The results indicated that Pd/anodic γ-Al2O3 catalyst is promising to eliminate the dangerous emissions of nitrous oxide greenhouse gas in the chemical industry via direct catalytic decomposition. Furthermore, the proposed elliptical replaceable microreactor is effective for complete N2O decomposition as it requires lower amounts of catalyst and energy compared to the other conventional reactors.

In this study, the bactericidal properties of the wing surface of two different Psalmocharias cicada species, Psalmocharias querula (PQ) and Psalmocharias akesensis (PA), are examined based on the organization and nano-topographical characteristics of the wing nanostructure. The bacterial killing capacity of the wings was assessed by counting the colony-forming units (CFU). Atomic force microscopy (AFM), scanning electron microscopy (SEM), and contact angle measurements were utilized to reveal wings nano-topographical structures and their impact on bacterial contact-killing efficiency. The role of surface roughness parameters on bacterial cell attachments and bactericidal properties of the wings was evaluated by analysis of topography results using histogram height distribution and power spectral density (PSD) methods. It was found that the skewness and kurtosis values of the cicada wing nanopillars significantly correlate with their shear-inducing capacity, confirming the higher bactericidal activity for PQ wing surface compared to PA wing surface.

In this Study, a novel modified PVDF-HFP/GO/ODS hollow fiber membrane fabricated by dry/wet jet spinning. The dope solution containing 12 wt% polymer, and different amounts of graphene oxide (GO) nanosheets (0, 1, 3 and 5%) were prepared in NMP as a solvent. Then the composite membranes were silanized using ODS in acidic condition. Various techniques such as SEM, AFM, FTIR, LEP, contact angle (CA) and tensile measurement tests were used to investigate the effects of modifications on the structure, surface chemistry, and performance of the membranes. The modified membrane exhibits a permeation flux of 34.1 ± 1.1 kg m − 2 h − 1 . Furthermore, the contact angle and LEP were increased from 115° ± 1.5 and 112 ± 4.5 kPa for PVDF-HFP membrane to 162° ± 1.7 and 181 ± 5.3 kPa for modified PVDF-HFP/GO/ODS membrane, respectively. The incorporation of GO in the membrane matrix induces the hierarchy roughness on the membrane surface and provides reactive hydroxyl sites for further chemical modification. Desalination of Caspian Sea water (CSW) was conducted using prepared membranes through direct contact membrane distillation (DCMD). Results showed that salt precipitation and permeation flux reduction partially occurred after 10 days for modified membranes. Finally, the membranes recovered by chemical cleaning in HCl solution (pH = 5).

On-chip phase separation of multiphase microflows at the divergence point of Y-shaped microfluidic junctions is an effective way for integrating continuous microstructured devices. In this study, flow pattern maps of various solvent pairs based on the volumetric flow rates of both phases have been drawn experimentally and compared with numerical prediction to investigate the effective domain for which complete phase separation occurred. Furthermore, sufficient separation of aqueous and organic phases at the end of the microchannel was achieved by controlling the pressure difference at the liquid-liquid interface via loading back-pressure on the organic phase. A mathematical model based on interfacial pressure balance was derived. It was found that organic phase outlet tube should be kept between the upper and lower values calculated from the model. Only narrow discrepancy between the model and experimental observation can be seen in using viscous organic solvents.

In this article, a novel module is presented to enhance the performance of air gap membrane distillation (AGMD) process. Experimental examinations were performed to modify a conventional AGMD module by presenting a new geometry and analyze the influence of this modification on the performance of the process. Also, three-dimensional (3D) numerical simulation was performed to reveal all aspects of this modification. In numerical study, the momentum, heat and mass transfer equations are solved with turbulent model (k-e realizable) to observe the flow feature inside the new AGMD geometries. Furthermore, the effect of radial baffles as well as feed flow rate (0.25, 0.50 and 0.75 kg/min) are investigated. In order to verify the numerical results, the simulated permeate flux was compared to the experimental data and low discrepancy (less than 6%) was observed. The results also indicate that the mass flux was improved (about 6%) as the rectangular-type module was replaced by the disk-type one. Moreover, our findings show that applying four, six and eight radial baffles to disk type modules significantly enhanced the permeate flux by 10, 13 and 14.7%, respectively. Most importantly, the applicability of the membrane distillation (MD) process for enrichment of 18 O water isotope of distilled water was studied using a laboratory operating disk-type AGMD module. This module was employed based on the best-performed geometry obtained from the numerical results. The achieved separation factor was 0.9823 which shows that this approach is a reliable method for isotope separation.

A one-dimensional non-isothermal steady state model was developed to simulate the performance of three-reactor configurations for the oxidative dehydrogenation of ethane (ODHE) to ethylene. These configurations consist of side feeding reactor (SFR), conventional fixed bed reactor (CFBR) and membrane reactor (MR). The performance of these reactors was compared in the terms of C2H6 conversion, C2H4 and CO2 selectivity and temperature profiles. The use of sectional air injections on the wall of SFR with a limited number of injection points showed that the performance of reactor significantly improves and optimum pattern of oxygen consumption is also obtained. Moreover, our SFR with a liquid coolant medium operates in an effectively controlled temperature profile that is comparable with that of the MR, which is cooled by a coolant stream of air. Hence, an enhancement in the level of selectivity is obtained for the SFR configuration. Consequently, the side feeding procedure can decrease the high operating temperature problem and low ethylene selectivity in the ODHE process. According to obtained results, the SFR would be a proper alternative for both the MR and CFBR.

An efficiency-based nonequilibrium model is proposed to simulate two industrial distillation columns. In this model, the behavior of trays is studied by considering the mass transfer at interphase. The interphase mass transfer is simply evaluated by the simultaneous solution of the vapor material balance equation and the definition of the Murphree efficiency. A MATLAB code is developed to implement the simulation procedure. For verification, the product compositions and plate temperatures are compared with the reported experimental data. The discrepancy of the experimental and simulation results is about 0.5% and 20% for the temperature and the product compositions for both columns, respectively.

In the present work, the cobalt catalysts supported on carbon nanotubes (CNTs) were prepared by impregnation method in the presence and absence of magnetic field. The prepared catalysts were employed to yield higher hydrocarbons via Fischer–Tropsch synthesis. It is explored that using magnetized water can effectively change the catalyst geometry in impregnation catalyst preparation method. For the preparation of different sizes of cobalt particles on the CNTs support, the physical properties of solvent (water) in impregnation process were changed using the magnetizing process. The results showed that the average particle sizes of impregnated cobalt nanoparticles were decreased by using magnetized water in impregnation step. In addition, in the magnetized treated cobalt catalyst, the cobalt particles mostly dispersed outside the tubes because the capillary forces decreased by reducing water surface tension. Furthermore, the experimental results showed that the probability of chain growth (α) and selectivity to heavier hydrocarbons increased in magnetized water treatment catalysts.

•Manipulation of the Cu surface morphology in a wide range by electropolishing treatment.•Comparison of the nucleation density of graphene at low pressure and atmospheric pressure CVD processes.•Controlling the evolution of the Cu surface morphology inside a novel confined space.•Growth of large-size graphene domains.

Nowadays, nanoparticles (NPs), especially silver nanoparticles (AgNPs), are introduced in a growing number of commercial products and their production is released into the environment and may adversely influence on organisms. Up to now, limited studies are available about toxicity effects of NPs on higher plants. In this work, the effects of AgNPs in comparison with silver nitrate (AgNO3) on some physiological parameters of the wheat (Triticum aestivum) were investigated. Silver nanoparticles and AgNO3 at 10 and 100 mg−1 L concentrations significantly decreased the fresh and dry weight of roots and shoots. The results showed that AgNPs and AgNO3 decreased plant tissue chlorophyll “a” and “b,” carotenoid and total protein contents of the leaves significantly. Both AgNO3 and AgNPs treatments also increased the amount of proline, lipid peroxidation and catalase activity of wheat seedling tissues. Results of this work revealed that exposure to silver nanoparticles and silver ions might cause negative aspects and toxicity problems in plants.

A new structured packing with the specific surface area of 2100 m2 m−3 (PACK-2100) was characterized through experimental and numerical studies to evaluate its performance in the distillation column. For serving this purpose, various operational conditions were studied to assess the main parameters such as wet pressure drop and liquid holdup of PACK-2100. The results indicate that the wet pressure drop and hold up values are enhanced in comparison to commercial ones. In addition, the pressure drop slowly increases from 0.5 to 25 millibar per meter of packing as mass flow rates of air and liquid flow are increased. In the similar manner, the holdup is raised from 12% to 33%. The numerical simulations were also performed to describe the flow pattern inside of the PACK-2100. The computational results confirmed that the liquid stream fall on the surface of packing forming the uniform film. The present study introduces the new packing of PACK-2100 with superior characteristics for special application in the systems with a low separation factor.

Experimental and numerical studies were conducted on the performance and capacity of structured packings for mixture separation with very low separation factor. Different formations and conditions of the innovative structured packing PACK-2100 with high surface area were studied to evaluate the main characteristics such as dry pressure drop. In addition, numerical simulation was performed to describe the details of the flow structure in these modified structured packings. Three-dimensional computational fluid dynamics modeling of PACK-2100 allowed for comparing the pressure drop in both laminar and turbulent flow regime. The obtained experimental and numerical data demonstrate the potential contribution of the packing to high-efficiency systems with low separation factor.

Experimental study of the performance of a gas centrifuge can be appreciably simplified if instead of isotopic mixtures, a binary mixture of gases with large molecular weight difference is used. The current study undertook this approach by injecting a 53%–47% (w/w) mixture of “Freon12-Freon22” into a gas centrifuge. The two parameters, whose investigation was the objective of the current study were: the feed flow rate (F), and the clearance between tail scoop and the rotor wall (d). The results demonstrated that changing the scoop-wall clearance has the most significant effect on the cut (θ), so that by fixing “d”, “θ” becomes nearly invariant. The head separation factor (α) exhibited the same dependency, but it was more influenced by the “F” than the “d”. Apparently the following regression exists between the inspected parameters:Decreasing “d” → Decreasing “θ” → Increasing “α”.Variations of the tail separation factor (β) with “F” or “d” was quite slight, even though similar to “α”, it was lowere...

In this paper, an experimental investigation is conducted to present a new cascade of the air gap membrane distillation (AGMD) for enrichment of H 2 18 O in natural water. The isotopic separation capability of the poly(vinylidene fluoride) (PVDF) nanofibrous membrane is compared with the conventional ploy(tetrafluoroethylene) (PTFE). To achieve this, appropriate PVDF electrospun membranes were prepared and applied in AGMD process to enrich H 2 18 O in natural water. Then, the theoretical cascade calculation is performed to obtain operational parameters such as arrangement of the cascade and the maximum enrichment. The simulated cascade is examined for the enrichment of H 2 18 O by PVDF membranes. The enrichment performance of the process the new cascade with 10 AGMD separation stages is implemented to increase. The results indicate that H 2 18 O/H 2 16 O isotopomeric separation factor increases through using PVDF nanofibrous membrane. The significant increase (more than 30%) is occurred in H 2 18 O concentration in the final product of AGMD cascade system. The findings suggest that the PVDF nanofibrous membrane performs better in the isotopomeric separation and presents superior cut-off value (around 85%) compared to commonly employed PTFE commercial membrane.

In this research, we have investigated the unintended graphene nucleation problem and its damaging effects on monolayer graphene synthesis in low-pressure chemical vapor deposition (LPCVD) process. This problem is the growth of graphene on the copper surface with no carbon feedstock. A new source of undesired carbon species was identified which has not been addressed so far. The hydrogen-rich heating stage was diagnosed as the onset of the unintended nucleation for the first time owing to the determinant catalytic role of hydrogen in this stage. It was found out that this problem leads to uncontrollable growth of multilayer graphene, growth of defective graphene film and also inhibition of the reliable synthesis of monolayer graphene. We managed to grow enhanced-quality monolayer graphene by developing some innovative solutions to the problem containing a general solution based on the hydrogen effects in the heating stage. The results reveal a significant decrease in the unintended nucleation density from ∼2000 to almost zero domains per 100 × 100 μm2 copper area. Furthermore, Raman, HRTEM and SAED analysis confirm the defect-free growth of monolayer graphene after employing the solutions. These findings could pave the way for the reliable synthesis of high-quality monolayer graphene as well as large-sized graphene domains.

Mixed matrix membranes (MMMs) based on two different MOFs (Cu-BTC and Cu-BDC) dispersed in Matrimid® 5218 were studied. The synthesized particles were characterized by N2 sorption measurements, FTIR, SEM, TGA and XRD. Also, SEM, XRD, TGA, FTIR and DSC analyses were used to evaluate the structure of the prepared membranes. The MMMs were tested in separation of helium from CH4 and N2 at 35 °C and feed pressure of 5 bar. The effect of operating temperature and feed pressure on the separation performance of MMMs was investigated. The cross sectional SEM micrographs showed good adhesion between fillers and the polymer, however at 30 wt. % loading of Cu-BTC, non-selective voids were found in some areas. For the MMMs with 20 wt. % loading of Cu-BTC, permeability of He was found 49.7 Barrer and ideal selectivities for He/CH4 and He /N2 were 217.1 and 168.5, respectively. The MMM comprising 30 wt. % of Cu-BDC was chosen as the best membrane with ideal selectivities of He/CH4 = 257.9 and He /N2 = 193.4, which developed by 96.7 and 96.2 % compared to pure Matrimid.

A laboratory experiment is described in which students measure the amount of cetirizine in allergy-treatment tablets based on molecular recognition. The basis of recognition is competition of cetirizine with phenolphthalein to form an inclusion complex with β-cyclodextrin. Phenolphthalein is pinkish under basic condition, whereas it’s complex form with β-cyclodextrin is colorless. Addition of the cetirizine leads to release of phenolphthalein from the phenolphthalein-β-cyclodextrin inclusion complex that alters the solution color under basic conditions. The intensity of the color change is proportional to the cetirizine concentration. This simple experiment provides an opportunity for students to become familiar with the concepts of inclusion complexes and molecular recognition. Students also gain hands-on experience with a spectrophotometer and engage in plotting a calibration curve based on absorbance or color changes and determination of cetirizine.

A new strategy to induce superhydrophobicity via introducing hierarchical structure into the polyvinylidene fluoride (PVDF) film was explored in this study. For this purpose nanofibrous composite films were prepared by electrospinning of PVDF and PVDF/graphene blend solution as the main precursors to produce a net-like structure. Various spectroscopy and microscopy methods in combination with crystallographic and wettability tests were used to evaluate the characteristics of the synthesized films. Mechanical properties have been studied using a universal stress-strain test. The results show that the properties of the PVDF nanofibrous film are improved by compositing with graphene. The incorporation of graphene flakes into the fibrous polymer matrix changes the morphology, enhances the surface roughness, and improves the hydrophobicity by inducing a morphological hierarchy. Superhydrophobicity with the water contact angle of about 160° can be achieved for the PVDF/graphene electrospun nanocomposite film in comparison to PVDF pristine film.

Continuous adsorption in stirred reactors in the form of carbon in pulp (CIP) and resin in pulp (RIP) is an established process for the extraction of gold and uranium. Under the circumstance of int...

E ) model and the cubic plus association (CPA) equa- tion of state (EoS) are compared in this study with respect to their accuracy in the correlation of PVTx for systems such as water/methanol, water/ethanol, water/benzene, water/toluene, water/methane, water/n-butane, water/n-pentane, water/ n-hexane, water/heptane, and water/octane, in supercritical conditions within temperature and pressure ranges of (573- 698 K) and (7.0-276.0 MPa), respectively. In the proposed EoS/G E model, Peng-Robinson (PR) equation of state, linear combination Vidal-Michelsen (LCVM) and Wong-Sandler (WS) mixing rules in conjunction with UNIQUAC activity coefficient model were used. Correlation of both CPA and EoS/G E models was evaluated by comparing the results with the experimental data. Average absolute relative deviation (AARD) for WS, LCVM, and CPA was found to be 2.99, 11.11 and 5.14%, respectively, indicating better correlation of WS model with the experimental data.

The study here deals with the plant synthesis of cadmium oxide nanoparticles using flowers extract ofAchillea wilhelmsiias the reducing agent. The photosynthesis is carried out at room temperature in the laboratory ambience. The aqueous cadmium ions when exposed to flower extract were reduced and resulted in their nanoparticles. The synthesized nanoparticles were characterized using techniques such as scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), and UV-visible absorption spectroscopy. Stable cadmium oxide nanoparticles were formed by treating aqueous solution of cadmium chloride (CdCl2) with the plant flower extracts as reducing agent.