External Mass Transfer Research Articles

Mass transfer in catalytic depolymerization: External effectiveness factors and serendipitous processivity in stagnant and stirred melts

Several heterogeneous catalysts are being developed to recycle plastics. Most operate in viscous polymer melts, where external mass transfer effects could limit the supply of co-reactants to active sites. External mass transfer can also impede the diffusion of long chain products away from the catalyst after each cut. Product egress limitations could potentially confer unintentional processivity to catalyst operation, i.e. a tendency for the catalyst to repeatedly cut the same chain after an initial encounter. We formulate reaction–diffusion equations to quantify mass transfer effects on the co-reactant transport to the catalyst and the degree of serendipitous processivity. Results are developed for catalysts in stagnant or stirred melts, with simple expressions involving Damkohler, Peclet, and Sherwood numbers, i.e. dimensionless combinations of rate constants, catalyst particle size, polymer diffusivities, and shear rates (where applicable). We estimate the impact of these effects for a spherical core–shell catalyst.

Post-processing of a lavender flowers solvent extract using supercritical CO2 fractionation

BackgroundSupercritical Fluid Extraction (SFE) was performed using an unconventional material, the solid extract of lavender flowers obtained by liquid solvent extraction and subsequent solvent elimination. MethodsSystematic extraction experiments were carried out at 8 MPa and 40 °C, and the extract was fractionated in semi-continuous mode in the SFE plant. To understand mass transfer phenomena driving the process, CO2 mass flow rates ranging between 0.60 and 1.50 kg/h were used, and yield vs. time curves were obtained. Significant findingsFractionation produced a cuticular waxes selective precipitation in the first separator and the floral fragrance in the second separator. The most abundant species in the extract were τ-cadinol (13%), lavandulol (10.5%), β-caryophyllene (10%), viridiflorene (8.5%), isocaryophyllene (6%), cedrenalol (4.5%), linalool (4%) and 1,8-cineol (4%). The fragrance contained no waxes, indicating that the fractionation was successful. At higher mass flow rates (from 0.90 to 1.50 kg/h), an asymptotic extraction yield of 5.2% w/w was obtained; whereas, at lower mass flow rates, the extraction yield was lower (2.3% w/w) since the vegetable bed was not completely wetted by the extraction fluid. The overall results indicated that an external mass transfer resistance controlled the process.

Assessment of biodegradation kinetics and mass transfer aspects in attached growth bioreactor for effective treatment of brilliant green dye from wastewater

In this study, Bacillus licheniformis immobilized with low-density polyethylene (LDPE) was employed to degrade Brilliant Green (BG) dye from wastewater in a packed bed bioreactor (PBBR). Bacterial growth and extracellular polymeric substance (EPS) secretion were also assessed under different concentrations of BG dye. The impacts of external mass transfer resistance on BG biodegradation were also evaluated at different flow rates (0.3–1.2 L/h). A new mass transfer correlation JD=5.71NRe-0.3 was proposed to study the mass transfer aspects in attached-growth bioreactor. The intermediates, namely 3- dimethylamino phenol, benzoic acid, 1–4 benzenediol, and acetaldehyde were identified during the biodegradation of BG and, subsequently degradation pathway was proposed. Han - Levenspiel kinetics parameters μmax and Ks were found to be 0.185 per day and 115 mg/L, respectively. The new insight into mass transfer and kinetics support the design of efficiently attached growth bioreactor to treat a wide range of pollutants.

Modeling and simulation of trickle bed reactors for the purification of 1-butene

Abstract In this contribution, a mathematical model of an industrial trickle-bed reactor employed in the purification of a C4 cut by selective hydrogenation of acetylenic or dienes compounds to obtain high purity 1-butene is presented. A reaction network of ten reactions is included in the model, with kinetics expressions and parameter estimation obtained from previous experimental studies on a commercial catalyst. Internal mass transfer resistances in the catalyst particles are significant; therefore the reaction-diffusion equations must be solved. External mass transfer resistances in the liquid phase were retained, while those in the vapor phase were negligible. The model was employed to analyze the reactor behavior by varying the inlet molar flow rate of hydrogen, the operating pressure, inlet temperature and the level of activity of the catalyst, taking into account its deactivation. It was demonstrated that the mass transfer resistances, inside and outside the catalyst particles, have a significant impact on the selectivity, but a careful operation of the reactor can improve the selectivity and extent the catalyst life. On the other hand, an alternative system was proposed, with two beds and a distributed input of H2, which led to a significant improvement in the selectivity.

Low-cost biosorption of Fe(II) and Fe(III) from single and binary solutions using Ulva lactuca-derived cellulose nanocrystals-graphene oxide composite film

The marine algal biomass of Ulva lactuca was utilized for the extraction of cellulose and the development of cellulose nanocrystals/graphene oxide film. Cellulose nanocrystals with 50–150 nm were produced by H2SO4 hydrolysis of the algal cellulose. The adsorption efficiency of the nanocomposite film for Fe(II) and Fe(III) ions was successfully evaluated using Box-Behnken design. The maximum removal for Fe(II) (64.15%) could be attained at pH 5.13, adsorbent dosage 7.93 g L−1 and Fe(II) concentration 15.39 mg L−1, while the biosorption of Fe(III) was 69.92% at pH 5.0, adsorbent dosage 2 g L−1, and Fe(III) concentration 15.0 mg L−1. However, in the binary system, the removal efficiency of Fe(II) was enhanced to 95.48% at Fe(II):Fe(III) ratio of 1:1, while the Fe(III) removal was increased to 79.17% at ratio 1:2. The pseudo-second-order kinetics exhibited better fitting to the experimental results of Fe(II) and Fe(III) adsorption in both single and binary systems. The intra-particle diffusion was prominent during the biosorption, but the effect of the external mass transfer was significant. The Langmuir, Freundlich, Langmuir–Freundlich, Temkin, and Dubinin-Radushkevich isotherms showed satisfactory fitting to the experimental data, but they differ in priority based on iron state and pH. The adsorption of Fe(II) in the presence of Fe(III) in a mixture was best represented by the extended Langmuir model, while the extended Langmuir–Freundlich model best fitted the adsorption of Fe(III). The FT-IR analysis indicated that physisorption through electrostatic interaction/complexation is the predominant mechanism for the adsorption of iron using the nanocomposite film.

The significance of granular activated carbon pore structure in modeling dissolved organic carbon removal in fixed-bed filters

A reliable model that describes DOC removal during biological-active granular activated carbon filtration for advanced wastewater treatment has to cover several aspects that influence biological and adsorptive removal processes. For this purpose, this work introduces a two-domain internal diffusion approach to a multicomponent adsorption model, which is combined with a traditional biofilm model for the first time. DOC was divided into fictive components according to biodegradability and adsorbability to calculate multicomponent adsorption equilibrium based on the ideal adsorbed solution theory. Adsorption kinetics included external mass transfer (diffusion through a boundary layer and a biofilm) and internal mass transfer (fast pore diffusion in the larger pores and slow surface diffusion in the micropores). Mass transfer in the micropore domain was implemented by adjusting the adsorptive driving force depending on the available internal surface area for DOC adsorption based on an empirical surface diffusion model. Simulated DOC breakthrough curves were sensitive to model parameters related to the pore structure of the granular activated carbon (GAC). The model was validated with two GAC types and empty bed contact times ranging between 6 and 33 min. The model results showed a good agreement with measured DOC breakthrough curves over the entire operation time, demonstrating the applicability and transferability of the model. In particular, the initial DOC breakthrough was well represented. However, some systematic deviations between measured and simulated DOC breakthrough curves were observed, which are probably due to the level of detail of the implemented biofilm model.

Adsorption mechanism and mass transfer modeling of cesium and europium ions adsorption onto hematite-loaded polyacrylamide-gel composite: Pore Volume and Surface Diffusion Model Approach

The overall adsorption rate of cesium (Cs+) and europium (Eu3+) ions onto hematite-loaded polyacrylamide-gel composite (HPAC) in single and binary pollutant systems was explained with diffusional model that takes into consideration both external mass transfer and intra-particle diffusion. The influence of changing system temperature on the overall adsorption rate of Cs+ and Eu3+ onto HPAC was studied. The fitting process of the experimental data with the three studied isotherm models (Langmuir, Freundlich and Prausnitz–Radke (P-R)) showed that Prausnitz–Radke model has the highest correlation coefficients with the smallest average relative error percentage. The maximum P-R adsorption capacity of HPAC decreased from 2.06 and 3.35 L/g in single pollutant solution to 1.02 and 1.51 L/g in binary pollutant solution at 298 K for Cs+ and Eu3+,respectively. The values of surface diffusion coefficient (DS) ranged within 10−8 for Cs+ and 10−8-10−9 cm2/s for Eu3+ in both studied single and binary pollutant systems. The external mass transfer coefficient (KF) was in the range of 10−4 for Cs+ and 10−3 cm/s for Eu3+ in both studied systems. Lastly, the Biot number (Bi) exposed that the diffusion inside the particle controlled the studied cations's adsorption onto HPAC material.

Adsorption mechanism of nonsteroidal anti-inflammatories in wastewater using regenerable adsorbent (CCL): statistical modelling isotherm, kinetics and thermodynamic comparative studies

ABSTRACT The study was performed to investigate the biosorption mechanism of Diclofenac Sodium and Ketotifen Fumarate onto CCL biosorbent using isotherms models (Langmuir, Freundlich). Effects of parameters influencing the biosorption such as temperature, pH, biosorbent dose, contact time and biosorbate initial concentration were all investigated and optimised using a batch system. The comparison between various models indicates that the nonlinear form of Langmuir model was the best way to describe the equilibrium data that were approved using error functions: the coefficient of determination (R2), Average relative error (ARE), the sum of the squares of the errors (SSE), Marquardt’s percent standard deviation (MPSD), Hybrid fractional error function (HYBRID), Sum of the absolute errors (SAE) and ‘sum of the normalised errors (SNE)’ parameter. The kinetics experimental data was best predicted by the pseudo-second-order model. The adsorption mechanism identified external mass transfer as the principal measure of velocity control step. Thermodynamically, the process is spontaneous, exothermic and the adsorption was more favourable at lower temperatures. It was found that the regeneration is required as it changes the surface morphology of the biosorbent. Therefore, CCL biosorbent is considered as cost-effective and eco-efficient for removing Diclofenac and Ketotifen adsorbate from aqueous media by adsorption technique especially with its low cost preparation and regeneration.

Prospective removal characteristics of noxious cationic dye using Cladophora catenata: a sustainable approach

ABSTRACT The discharge of Cationic Reactive Yellow 147 (CRY 147) into water bodies may have major consequences for human health and the aquatic ecosystem. Environmentally friendly, inexpensive, and efficient sorbents are being investigated for removing hazardous dyes from textile drain water. The objective of the current study is to explicate the removal of CRY 147 from the synthetic textile medium using Cladophora catenata (C.catenata). The C.catenata was analysed by FTIR, SEM/EDS, and BET methods. The research examined the impacts of different experimental process variables on adsorption. Batch adsorption studies were performed to assess the absorbent’s capacity to capture CRY 147 from aqueous systems. The following factors were investigated: pH, adsorbent-dye ratio, contact duration, CRY 147 concentration, and temperature. The adsorption process matched the Langmuir model in equilibrium studies and the pseudo-kinetic second order in kinetic behaviour. The C. catenata has a maximal monolayer capacity of 87.71 mg g−1 for the elimination of CRY 47. The Boyd’s plot confirmed the external mass transfer as the rate-limiting step. Thermodynamic studies demonstrated that the adsorption process was exothermic and spontaneous. The primary mechanisms of CRY 147 adsorption on C. catenata were found to be electrostatic inter linkage, n-π and π-π interactions, and hydrogen bonding. In addition, a desorption investigation with different eluents was carried out to determine the reusability of C.catenata. Furthermore, the C.catenata showed good stability and regenerability up to four cycles. Subsequently, the findings revealed that C. catenata might be a low-cost, promising, and green sorbent for removing CRY 147 from synthetic suspension/textile wastewater.

Experimental study and kinetic modeling of methanol conversion to propylene with co-feeding of C4 and C5/C6 hydrocarbon cuts over a ZSM-5 catalyst.

Extensive experimental data were used to develop a comprehensive kinetic model for the methanol to propylene (MTP) process over a ZSM-5 catalyst. Preliminary experiments were performed to determine the reaction conditions that would ensure the absence of external (film) and internal mass transfer resistances. The kinetic experiments were subsequently carried out at 420-500 °C under conditions where mass transfer limitations were absent. A detailed reaction network was proposed for the MTP process based on the experimental product distribution and various reported kinetic models in the literature. According to the first series of experiments (without C4 and C5/C6 recycle streams) conducted at various temperatures, the best yield for propylene production was achieved at 480 °C with a water to methanol ratio of 0.7. Subsequently, kinetic experiments were performed at 480 °C and a water to methanol ratio of 0.7 using feeds with different amounts of C4 and C5/C6 hydrocarbons as recycle streams. Species material balances for the integral tubular reactor along with power-law rate functions and the Arrhenius equation for rate constants were employed in an optimization algorithm to obtain the kinetic parameters. The predictive ability of the model was checked against experimental data, and the kinetic parameters were validated by additional experiments.

Kinetics of H2S removal using alkaline residue as in-bed sorbent in fluidized bed gasification of biomass and wastes

The use of alkaline residue from the acetylene industry (carbide slag, CS) as in-bed sorbent to remove H2S from syngas from biomass/waste fluidized bed (FB) gasification was investigated. Measurements were conducted in a laboratory FB applying differential conversion technique, tracking the reaction using both gas measurements and solid analysis. Apparent reaction kinetics was obtained, without external mass transfer limitations, for different gas mixtures containing CO2, H2O, CO, H2 and CH4, having relatively low H2S concentration (500–1000 ppm). The addition of CO2 and H2O to an N2-H2-H2S mixture showed that the reaction rate was reduced in the presence of these species. Varying the H2 concentration between 7 and 14% in simple (N2-H2-H2S) reactive gas mixtures did not affect the results, while both CO and H2 potentially affected the reaction rate if also CO2 was present in the gas. Other operating parameters, such as sorbent particle size, sulfidation- and calcination temperature also affected the CaO sulfidation rate, which increased with temperature between 800 and 900 °C and was enhanced by higher calcination temperature. Specific surface area and pore size distribution of the calcined CS was measured before and after the sulfidation reaction, showing that CS maintained a large fraction of its original pore volume even after most of the CaO had been converted into CaS. The sulfidation rate of calcined limestone was also measured for comparison showing that the reaction rate using CS was slightly lower, but similar to that using limestone, showing that CS is a promising alternative to conventional calcium-based sorbents for high temperature H2S removal, contributing to promote the circular economy, while avoiding the current stacking of CS at the acetylene production sites.

Interplay between membrane imperfections and external concentration polarization

Reverse osmosis membranes provide a highly effective and efficient barrier against various kinds of pollutants. Their reliability depends on the integrity of the active layer: in case the active layer is damaged and contains imperfections, unfiltered feed solution can contaminate the permeate. Various types of integrity monitoring techniques have been developed to verify membrane performance, of which the rejection of fluorescent dyes is a well-established technique. Fluorescent dyes are however relatively small solutes for which the membranes can display non-zero diffusive permeability, such that not all dye passage can be attributed to membrane imperfections. Additionally, fluorescent dyes are subject to external concentration polarization (ECP) during filtration, causing a flux-dependent enrichment at the membrane surface, further complicating the analysis of dye rejection data. This study presents a model to discern between membrane permeability, enrichment by ECP and passage through imperfections. The consequences of imperfections on solute passage are explored, showing that imperfections only contribute significantly to the passage of solutes with a low membrane permeability. This leads to underestimates of the external mass transfer coefficient, with the error being increasingly large with decreasing membrane permeability coefficient, relative to the case of an imperfection-free membrane. This error is then related to the proportionality of the Sherwood number, used to calculate external mass transfer coefficients, with solute diffusivity, allowing the quantification of the contribution of imperfections to water flux. The model was experimentally verified using Pyranine rejection in two membrane types, both operated in a lab-scale flat sheet crossflow test system, finding proof of imperfections in one membrane type.

The use of agro-industrial residues of coffee ( Coffea arabica) for the removal of mercury from water

Contamination of water bodies by heavy metals is a continuously growing environmental issue. High concentrations of mercury (Hg) in river waters are a recognized environmental problem, because it is one of the most toxic heavy metal ions as it causes damage to the central nervous system. Its negative impact has led to the development of different methods for the treatment of effluents contaminated with Hg(II). The aim of this article is to evaluate the use of coffee ( Coffea arabica) residues as adsorbent of Mercury in an aqueous solution. Four kinetic models, including intraparticle diffusion, pseudo-first-order, pseudo-second-order, and Elovich kinetic models were applied to explore the internal mechanism of mercury adsorption. Results indicate that the pseudo-first-order and pseudo-second-order models could accurately describe the adsorption process. It means that chemical adsorption play an important role in the adsorption of mercury by activated carbon. Meanwhile, the external mass transfer process is more effective in controlling the activated carbon mercury adsorption according to the fitting result of the pseudo-first-order model. The fitting to Langmuir’s model suggested that the material surface is energetically homogeneous. The technique of contaminated biomass encapsulation proved to be safe for short-term disposal when metal recovery is not desired.

Modeling and experimental investigation for development of Combined Electrolysis and Catalytic Exchange process for hydrogen isotope separation

A process based on the Combined Electrolysis and Catalytic Exchange (CECE) has been developed for separation of hydrogen isotopes. Indigenously developed Platinum supported on Carbon Aerogel based hydrophobic catalyst was used for hydrogen-water isotope exchange reaction combined with hydrophilic packing in a catalytic exchange column. The exchange column has been studied in detail for various operating conditions in this study. The intrinsic kinetics for the catalytic reaction was determined through spinning basket reactor experiments, and activation energy was estimated to be 29.7 kJ/mol. The overall mass transfer co-efficient in a mixture of hydrophilic packing and hydrophobic catalyst packed bed was determined experimentally in a pilot scale counter current trickle bed reactor to be in the range of 0.15–0.25 s-1 for the proposed range of operating conditions. Individual mass transfer resistances for vapour-liquid mass transfer, external gas mass transfer and gas-solid mass transfer were estimated using widely accepted empirical correlations. Under benchmark operating conditions, the Damkohler number for the exchange column was found to be between 0.10 and 0.16, indicating a significant contribution of surface reaction to overall mass transfer resistance. The vapour liquid mass transfer was found to be fast compared to the gas-vapour reaction. Therefore, increasing hydrophobic catalyst proportion relative to hydrophilic packing was found to increase the overall mass transfer. A steady state process model has been developed to predict the performance of overall exchange process using the experimentally determined parameters. Validation of the process model was carried out using the experimental data generated on the pilot scale trickle bed reactor. Optimum operating conditions of temperature, hydrophobic catalyst to hydrophilic packing ratio, gas and liquid superficial velocities were determined.

Adsorption, regeneration and kinetic of gas phase elemental mercury capture on sulfur incorporated porous carbon synthesized by template method under simulated coal-fired flue gas

A sulfur incorporated porous carbon (SIC) was synthesized by utilizing template method with precursor of 2-thiophene ethanol (C6H8OS) and thymol blue (C27H30O5S). Gas phase elemental mercury capture and regeneration capability of the SIC was explored in a fixed-bed experimental system. Mercury capture product on the SIC was studied by using Hg-TPD experiment. The kinetic parameter, activation energy, and mass transfer characteristic of mercury capture by the SIC was analyzed by using different mathematical models to reveal the mechanism of mercury removal. The results show that the SIC displays excellent mercury capture capability under different flue gas component with adsorption product of HgS. Coexistence of SO2 and H2O in flue gas slightly promotes mercury capture with formation of a small amount of HgSO4. The SIC also exhibits good regeneration ability that after multiple cycles of mercury capture and regeneration, the SIC still keeps a mercury capture rate of 90%. This is because after thermal regeneration, the group of C-S-C on the SIC gets restore and the adsorbed oxidized sulfur is released. Mercury adsorption on the SIC has better thermal stability compared to traditional activated carbon with an adsorption energy of −62.82 kJ/mol, which belongs to chemisorption. Mercury capture on the SIC is firstly dominated by surface adsorption and then converts to internal diffusion adsorption. External mass transfer is mercury adsorption control step and increase of initial mercury concentration promotes global mass transfer mainly via improvement of internal diffusion rate.

Using Confocal Laser Scanning Microscopy to Analyze the Mass Transfer in the Protein A Medium of a Silica Matrix

Mass transfer in a protein A medium with a silica matrix was analyzed in this study. Using confocal laser scanning microscopy, we monitored the positional and temporal changes in the polyclonal human IgG during batch adsorption. A simple theoretical model based on Fick’s law of diffusion and Langmuir adsorption was used to numerically approximate the external and intraparticle mass-transfer properties of IgG in single particles. The diffusivities found in this study were validated by comparing with the values reported in other studies and also by using numerical calculation to reproduce the experimentally obtained breakthrough curve.

Influence of the Distance between Two Catalysts for CO2 to Dimethyl Ether Tandem Reaction

AbstractTandem reactions, with their great potential for reduction of capital and operational costs, reaction time, and byproducts are becoming more prominent. Among possible tandem reaction systems for direct conversion of CO2 to green fuel, dimethyl ether synthesis via methanol route is of vital importance. However, there are several parameters which must be considered for the combination of two catalysts to achieve promising performance, of those, the distance between the two catalysts is a crucial one. This distance can affect the overall performance of the tandem system by causing external mass transfer limitations or the poisoning of the catalysts. This work presents a systematic study on the influence of the distance between the two catalysts for the CO2 to dimethyl ether tandem system.

Removal of Cr(VI) from aqueous solution by Rice-husk-based activated carbon prepared by Dual-mode heating method

Rice husk-based activated carbon was prepared with the help of zinc chloride using microwave and electrical dual-mode heating. The pore characteristics and chemical properties of rice husk-based activated carbon (RH-AC) were characterized by BET, XRD, Raman spectra, FTIR and pHIEP (pH of isoelectric point). The specific surface area of RH-AC is 1719.32 m2/g with a total pore volume of 1.05 cm3/g. The performance of RH-AC for removing Cr(VI) from aqueous solution was examined considering the variation of the contact time (0–120 min), pH value (2.0–9.0), adsorbent dose (0.5–3.0 g/L), initial concentration (28–145 mg/L) and solvent temperature (15–45 °C). The ideal pH for Cr(VI) removal is between 2.0 and 3.0 with the equilibrium time of 90 min, achieving the maximum adsorption capacity of 56.82 mg/g with the pH of 3.0. Comparable study on the established kinetic models and isotherms to simulate the removal of Cr(VI) by RH-AC was carried out to sort out the inherent mechanism of the absorption. Reasonable agreements could be obtained by the pseudo-second-order kinetic model and Langmuir, Freundlich and Tempkin isothermal models. Results from Body model simulation suggest that external mass transfer was the essential cause for rate-controlling in the adsorption process of Cr(VI).

An analytical solution of the effectiveness factor of photocatalytic reactors based on Robin boundary conditions

An analytical expression of the effectiveness factor of photocatalytic reactors that accounts for external mass transfer limitations is presented. The solution is based on Robin boundary conditions introducing the Sherwood number as the parameter that accounts for the external mass transfer limitations. Regions highlighting free diffusion, diffusion limitations, and external mass transfer limitations are identified based on the Thiele Modulus and the Sherwood number. At low values of the Sherwood number, the internal diffusion and reaction rate-limiting regions are surpassed by the external mass transfer limitations. A cut-off value of the Sherwood number below which external mass transfer limitations cannot be ignored is 0.55. The evaluation of the model showed that under Dirichlet boundary condition the model converges to literature models from similar studies. This 1-D model looked at the Sherwood number across a broad scope and accounted for a broader range of limitations associated with immobilized photocatalytic films.

Observation and Isochoric Thermodynamic Analysis of Partially Water-Filled 1.32 and 1.45 nm Diameter Carbon Nanotubes

Recent measurements of fluids under extreme confinement, including water within narrow carbon nanotubes, exhibit marked deviations from continuum theoretical descriptions. In this work, we generate precise carbon nanotube replicates that are filled with water, closed from external mass transfer, and studied over a wide temperature range by Raman spectroscopy. We study segments that are empty, partially filled, and completely filled with condensed water from -80 to 120 °C. Partially filled, nanodroplet states contain submicron vapor-like and liquid-like domains and are analyzed using a Clausius-Clapeyron-type model, yielding heats of condensation of water inside closed 1.32 nm diameter carbon nanotubes (3.32 ± 0.10 kJ/mol and 3.72 ± 0.11 kJ/mol) and 1.45 nm diameter carbon nanotubes (3.50 ± 0.07 kJ/mol) that are lower than the bulk enthalpy of vaporization and closer to the bulk enthalpy of fusion. Favored partial filling fractions are calculated, highlighting the effect of subnanometer changes in confining diameter on fluid properties and suggesting the promise of molecular engineering of nanoconfined liquid/vapor interfaces for water treatment or membrane distillation.