Three-dimensional honeycomb-like porous carbon derived from corncob for the removal of heavy metals from water by capacitive deionization

In this study, porous carbon (3DHPC) with a 3D honeycomb-like structure was synthesized from waste biomass corncob via hydrothermal carbonization coupled with KOH activation and investigated as a capacitive deionization (CDI) electrode material. The obtained 3DHPC possesses a hierarchal macroporous and mesoporous structure, and a large accessible specific surface area (952 m² g⁻¹). Electrochemical tests showed that the 3DHPC electrode exhibited a specific capacitance of 452 F g⁻¹ and good electric conductivity. Moreover, the feasibility of electrosorptive removal of chromium(vi) from an aqueous solution using the 3DHPC electrode was demonstrated. When 1.0 V was applied to a solution containing 30 mg L⁻¹ chromium(vi), the 3DHPC electrode exhibited a higher removal efficiency of 91.58% compared with that in the open circuit condition. This enhanced adsorption results from the improved affinity between chromium(vi) and the electrode under electrochemical assistance involving a non-faradic process. Consequently, the 3DHPC electrode with typical double-layer capacitor behavior is demonstrated to be a favorable electrode material for capacitive deionization.

A porous carbon electrode with a 3D honeycomb-like structure demonstrates a high removal efficiency for the removal of chromium(vi) from water.     

Giant surfactant-stabilized N2-foam for enhanced oil recovery after water flooding

A novel giant surfactant, APOSS-PS₅₀, possessing good surface activity, and viscosifying and reinforcing ability as a foam stabilizer, was synthesized successfully to enhance the physical properties of foaming solutions and foam. APOSS-PS₅₀ was widely distributed at the foam gas–liquid interface and adjacent liquid layers through diffusion and adsorption, obviously decreasing the surface tension and improving the foamability and stability of the foam. Furthermore, the aggregation of APOSS-PS₅₀ in the foam films resulted in the formation of a self-assembled nano-sized network through supramolecular interactions (such as hydrogen bonding, π–π stacking, and van der Waals attraction), thus increasing the foam viscoelasticity, including its interfacial viscoelastic modulus and apparent viscosity. Meanwhile, from the sandpack flooding experiments, compared with HPAM/AOS (HPAM: partially hydrolyzed acrylamide and AOS: alpha olefin sulfonate), the differential pressure and final oil recovery after APOSS-PS₅₀/AOS foam flooding increased by 23.5% and 23.2%, up to 2.68 MPa and 81.7%, respectively. In general, APOSS-PS₅₀ significantly promoted the plugging, profile control and oil displacement performance of foam.

A giant surfactant with high surface activity and strong viscosifying ability was prepared through a facile one-pot procedure for foam stabilization in EOR projects.     

Corrosion resistance for superwetting immiscible oil/water separation porous materials

In this paper, we first fabricate a 3D porous FZCF (FAS-modified ZnO-grown copper foam) with robust superhydrophobicity in air and superoleophilicity under water and the repeatable superwettability, and then mainly explore and analyze its corrosion resistance. The superhydrophobic–superoleophilic FZCF as an immiscible oil/organic solvent separation material shows high adsorption capacity and separation efficiency due to its heterogeneous micro–nano structures and low surface energy. It has excellent corrosion resistance under various pH conditions, and can serve as a corrosion protective barrier that prevents metal from contacting corrosive seawater in marine applications. Adsorbed oils also make superoleophilic FZCF keep its durability and stability after suffering attack in strong acid and alkali environments for a long time. Superwetting porous FZCF material that possesses outstanding excellent corrosion resistance demonstrates potential applications in many industrial fields such as oily wastewater treatment and marine oil spill accidents.

Superwetting porous FZCF as immiscible oil/organic solvents separation material that possesses excellent corrosion resistance can be widely applied in many industrial fields such as oily wastewater treatment and marine oil spill accidents.     

Optimization of closed-cycle oil recovery: a non-thermal process for bitumen and extra heavy oil recovery

Energy from unconventional resources includes bitumen and extra-heavy oil that represent two-thirds of the known resources in the world. Extra-heavy oil and bitumen are currently recovered using thermal processes having a large carbon footprint and significant environmental impacts on water resources. A novel process is proposed: closed-cycle oil recovery (C-COR). C-COR is a greener alternative to provide energy from these unconventional resources with minimal water consumption. C-COR relies on recovering oil solubilized within a single-phase microemulsion, eliminating the need for viscosity reduction to both mobilize heavy oil or to transport it. Proof-of-concept work was conducted using conventional phase behavior experiments with extracted oil and surfactant formulations to develop a surfactant formulation for oil recovery using C-COR. As a part of process development and scale-up, we conducted flow experiments presented in this paper. We learned that a high degree of surfactant adsorption, which negatively impacted the C-COR process, resulted at low pH levels. These findings required modifying traditional static batch tests (phase behavior studies) using actual oil sand instead of the extracted oil. These unorthodox tests revealed that surfactant adsorption caused low oil solubilization and that alkali can be used to reduce adsorption, improving oil solubilization. In addition, unique flow experiments were designed to optimize the delivery and recovery process and are presented in this paper. The unique batch tests and flow experiments were conducted using oil sands from Canada to optimize the process. The proposed optimized approach would employ intermittent flow (soaking) that would result in the fastest recovery of about one-third of the OOIP, followed by continuous injection to recover an additional 10% OOIP, ending with thermal enhancement to recover another 25% OOIP for a total of 61%.

The conceptual application of a single-phase microemulsion in the closed-cycle oil recovery approach for bitumen and extra-heavy oil reserves.     

A mechanistic investigation of low salinity water flooding coupled with ion tuning for enhanced oil recovery

Oil recovery by low salinity water flooding (LSWF) from carbonate reservoirs has gained tremendous attention in recent years due to its cost-effectiveness and environment-friendly nature. The mechanisms of low salinity water flooding for enhanced oil recovery are very complex and depend on the mineralogy of the formation rock, properties of injection brine and reservoir fluids. The present work aimed at the optimization of salinity and concentration of potential determining ions (PDIs) in injection water for enhanced oil recovery from carbonate reservoirs. Initially, we conducted a series of experiments on the dilution effect of seawater (SW) with the help of rock/fluid and fluid/fluid interactions via interfacial tension (IFT), zeta potential and contact angle measurements. This offered an optimum salinity (20dSW) with an 11% increase in recovery of the original oil in place (OOIP) over the SW injection in secondary flooding mode. Then, the ion tuning was done on the optimum salinity (20dSW) by manipulating the PDIs (Ca²⁺, SO₄²⁻ and Mg²⁺) while keeping ionic strength constant. The properties of ion tuned brine were optimized by zeta potential and contact angle measurements. The core flooding experiments performed with the injection of designed ion tuned water obtained by dilution and ion tuning of SW showed more than 20% OOIP as incremental recovery over the SW injection. Effluent analysis after the flooding confirms that the main mechanisms for enhanced oil recovery include calcite dissolution and wettability alteration due to interplay of PDIs.

The combined effects of dilution and ion tuning of seawater for enhanced oil recovery from carbonate reservoirs. Dominating mechanisms are calcite dissolution and the interplay of potential determining ions that lead to wettability alteration of rock surface.     

Enhanced oil removal from water in oil stable emulsions using electrospun nanocomposite fiber mats

Fibrous mats with hydrophobic and oleophilic properties have been fabricated and used as absorbents of oil from stable water in oil emulsions. The mats were prepared by initially mixing two polymers, poly(methyl methacrylate) (PMMA) and polycaprolactone (PCL), in a common solvent. The subsequent electrospinning of the prepared solutions resulted in the production of mechanically stable fiber mats, with enhanced oil absorption capacity and oil absorption selectivity from the emulsions, compared to the pure PMMA or PCL mats. Furthermore, the formed fibrous substrates have been successful in the absorption of oil from different emulsions with a wide range of oil content, from 10 to 80 v%. The performance of the fibrous mats was optimized by the incorporation of hydrophobic silica nanoparticles, reaching oil absorption capacities of 28 g g⁻¹ and negligible water uptake, in the emulsions with 80 v% oil content.

Fibrous mats with hydrophobic and oleophilic properties have been fabricated and used as absorbents of oil from stable water in oil emulsions.     

Recovery of extra-heavy oil and minerals from carbonate asphalt rocks by reactive extraction

Quite different from the Canadian oil sands, the Indonesian asphalt rocks proved to be carbonate unconventional oil ores. The strong interactions between asphalt and minerals make water-based extraction work poorly in separating this kind of ore. Herein, a reactive extraction process has been proposed to separate asphalt and mineral solids from the ores through dissolving the mineral solids (i.e., carbonate minerals, metal oxides, etc.) by acids (formic acid). It is evidenced that most of the asphalt could be recovered and collected on the top of the solution by generated CO₂. What''s more, the unreacted formic acid could be recycled in this process. The dissolved metal ions could be efficiently recovered to obtain different by-products by chemical settling and crystallization. The amount of residual solids settled at the bottom of the reactor is very small. Further tests show that the reaction efficiency is highly dependent on the operational conditions, including temperature, stirring rate, acid dosage, concentration of acid, etc. It is also found that the reaction could allow minerals to be redistributed in different phases. Although some metal elements could be dissolved into solution, elements such as Fe, Al, S, Si, and Ti are observed to accumulate in asphalt froth. In addition to reacting with minerals, formic acid is also found to reduce asphalt viscosity. This reduction improves the reaction efficiency. Based on primary evaluations, the above findings suggest that the reactive extraction would be a potential process to exploit the Indonesian asphalt rocks (or other similar ores) due to its full recovery to all materials.

A reactive extraction was applied to recover heavy and minerals from carbonate asphalt rocks.     

Beneficial use of ultrasound irradiation in synthesis of beta–clinoptilolite composite used in heavy oil upgrading process

A novel beta–clinoptilolite composite was prepared from beta zeolite and alkaline treated clinoptilolite by employing conventional and sonicated mixing procedures. Parent and prepared catalysts were characterized by XRD, FE-SEM, N₂ adsorption–desorption and NH₃-TPD analyses. Prepared composite of beta zeolite and treated clinoptilolite exhibited improved structural properties especially upon sonicated mixing procedure. Employing ultrasound irradiation notably improved beta distribution in the composite and increased mesoporous volume and specific surface area from 0.245 cm³ g⁻¹ and 171.3 m² g⁻¹ in conventionally mixed composite to 0.353 cm³ g⁻¹ and 232.9 m² g⁻¹ in sonicated sample. Catalytic performance of prepared composite was evaluated in heavy oil upgrading process in a continuous fixed bed apparatus. Liquid product was specified by conducting SIMDIS-GC and GC/MS analyses. Spent catalysts were characterized by TGA, FTIR and XRD. Beta–clinoptilolite composite containing only 30 wt% of beta zeolite, exhibited similar performance to beta zeolite catalyst by resulting 75.3% viscosity reduction while producing lower amount of coke. Amount of light hydrocarbons produced over beta–clinoptilolite composite was 33.51 wt% while beta zeolite catalyst produced 35.58 wt% light hydrocarbons in upgrading process. Ultrasound irradiated composite showed more stable structure in catalytic cracking procedure compared to conventionally mixed composite. After 5 h time on stream, relative crystallinity of clinoptilolite phase in the conventionally mixed composite was reduced by 34.5% while sonicated sample remarkably preserved its structure during the reaction and only 1% reduction occurred for this sample.

Beta–clinoptilolite composite synthesized in the presence of ultrasound irradiation exhibited high stability in heavy oil upgrading process while producing equal amount of light fuels and lower amount of coke compared to beta zeolite catalyst.     

Efficient alkaloid capture from water using a charged porous organic polymer

Berberine hydrochloride (BH), an important alkaloid, can be captured from water and released in organic solution circularly by a charged porous polymer (TPB–HCP), which is hypercross-linked using the cost-effective Friedel–Crafts reaction using sodium tetraphenylborate as the monomer. With high BET surface area, hierarchical porous structure and charged characteristics, TPB–HCP displays excellent adsorption capacity for BH owing to the synergistic effects of size matching and electrostatic interaction.

A charged porous polymer displays excellent adsorption capacity for berberine hydrochloride from the synergistic effects of size matching and electrostatic interaction.     

A review of femtosecond laser-structured superhydrophobic or underwater superoleophobic porous surfaces/materials for efficient oil/water separation

Oil/water separation (OWS) technology has become an increasingly crucial tool to protect the environment and reduce the economic losses caused by the discharge of oily wastewater and oil spills. Recently, porous materials with superwettability have been applied in effective OWS and have achieved tremendous success. Herein, we review recent advancements of OWS utilizing femtosecond (fs) laser-structured superhydrophobic or underwater superoleophobic porous materials. We will review the enabling materials processing and treatment methods, their surface wettability, the separating methods and processes, and the separation mechanisms. Inspired by lotus leaves and fish scales, superhydrophobic and underwater superoleophobic properties are artificially achieved on substrate surfaces by fs laser processing. By using fs laser-structured superwetting porous materials, various oil/water mixtures (OWMs) are successfully separated through different separation methods. Presently, the research of fs laser-based OWS is still in its infancy. We will also discuss the current challenges and future prospects in this emerging field. It is expected that the advanced features of fs laser microfabrication will lead to exciting applications for OWS.

Recent applications of the femtosecond laser-structured superhydrophobic or underwater superoleophobic porous materials in oil/water separation are summarized in this review.     

Using starch graft copolymer gel to assist the CO2 huff-n-puff process for enhanced oil recovery in a water channeling reservoir

The CO₂ huff-n-puff process is an effective method to enhance oil recovery (EOR) and reduce CO₂ emissions. However, its utilization is limited in a channeling reservoir due to early water and gas breakthrough. A novel starch graft copolymer (SGC) gel is proposed for treating the channels and assisting with the CO₂ huff-n-puff process. Firstly, the bulk and dynamic performances of the SGC gel including rheology, injectivity and plugging ability are compared with the polymer gel in the laboratory. Then, 3D physical models with water channels are established to reveal the EOR mechanisms of gel assisted CO₂ huff-n-puff. Several pilot tests of gel assisted CO₂ huff-n-puff are also discussed in this paper. The bulk and dynamic experimental results show that although these two gelants have similar viscosities, the SGC gelant has a better injectivity compared with the polymer gelant. The SGC gel is predominantly a viscous solution, which make it easier to flow through the pore throats. The RF of the SGC gelant is only 0.58 times that of the polymer gelant. After the gelation, a 3D network-like gel with a viscosity of 174 267 mPa s can be formed using the SGC gelant. The RRF of the SGC gel is about three times that of the polymer gel, which shows that the SGC gel has a stronger plugging ability within the porous media. The 3D experimental results show that four cycles of gel assisted CO₂ huff-n-puff can achieve an EOR of 11.36%, which is 2.56 times that of the pure CO₂ huff-n-puff. After the channels are plugged by the SGC gel, the remaining oil of the near-wellbore area can be first extracted by CO₂, and the oil of the deep formation can then be effectively displaced by the edge water. Pilot tests on five wells were conducted in the Jidong Oilfield, China, and a total oil production of 3790.86 m³ was obtained between 2016 and 2021. The proposed novel SGC gel is suitable for assisting with the CO₂ huff-n-puff process, which is a beneficial method for further EOR in a water channeling reservoir.

A starch graft copolymer (SGC) gel is proposed to assist CO₂ huff-n-puff for further enhanced oil recovery in a water channeling reservoir. The SGC gelant can form a 3D solid-like gel, and then effectively enlarge CO₂ sweep efficiency.     

A multiple model approach for evaluating the performance of time-lapse capsules in trapping heavy metals from water bodies

Adsorption by ion-exchange resins has been widely used as a cost-effective method for removing numerous hazardous materials, particularly heavy metals, from aqueous solutions. For effectively detecting the illegal discharge of industrial wastewater containing heavy metals, we developed “time-lapse capsules” to trap metallic ions from water bodies. Despite recent progress in the development of time-lapse capsules, a fundamental understanding was still needed to unravel the adsorption behavior of different heavy metals for further improvement of the design and scale-up of the capsule. In this study, three different approaches, viz., response surfaces (from the statistical point of view), time-dependent diffusion-controlled models (from the kinetic point of view), and adsorption isotherms (from the equilibrium point of view), were utilized to evaluate the effect of operating factors on the adsorption of heavy metals from watershed using time-lapse capsules. The obtained results indicated that the key parameters, such as adsorption rate constant, diffusivity, and maximum adsorption capacity, could provide insights into the basis of design criteria.

This article applies multiple approaches for evaluating the effect of operating factors on the adsorption of heavy metals from watershed using time-lapse capsules.     

A N-doped porous carbon derived from deep eutectic solvent for adsorption of organic contaminants from aqueous or oil solution

Porous N-doped carbon material (NCM) derived from deep eutectic solvent (DES) is successfully prepared. The preparation of NCM depends mainly on heating treatment and does not demand activation and filtration. The heating process contains three steps: (1) forming a DES that consists of glucose and urea at 100 °C; (2) preparing dried precursors by microwave; (3) and carbonizing the precursor. After heating, the resulting NCM can be obtained. The as-prepared NCM exhibits high specific surface area, rich micropores and strong Lewis basicity. Accordingly, NCMs show good adsorption performance for 4-nitrophenol or methylene blue in aqueous solution and thiophenic sulfurs in the oil phase. Apparently, NCM derived from DES not only possesses a simple preparation process, but also can remove a wide spectrum of organic pollutants. Therefore, the NCM prepared here may be promising for practical application.

Porous N-doped carbon material (NCM) derived from deep eutectic solvent (DES) is successfully prepared.     

Preparation of a porous superhydrophobic foam from waste plastic and its application for oil spill cleanup

In order to cope with the increasing oil spill accidents and the intentional discharge of oily wastewater, a new oil-adsorbing material with superhydrophobicity and reusability is needed. In this paper, waste plastic was used to fabricate an alveolate polystyrene (PS) foam to reduce secondary pollution. The PS foam was synthesized from a high internal phase Pickering emulsion (HIPPE) technique in a one-step process. The emulsion was stabilized by a co-Pickering system of Span 80 surfactant and SiO₂ particles. To explain the super stability of the HIPPE, a novel model of the water-in-oil droplet was promoted. The obtained SiO₂@PS foam exhibited a multi-order-porous structure, and displayed superhydrophobicity and superoleophilicity. It can selectively remove various oily contaminants from water with a high adsorption capacity of 20.4–58.1 g g⁻¹ at a fast rate. The oil-adsorbed material can be reused by simple centrifugation, and no more than a 1% decline was obtained in the oil adsorption after 10 cycles. Therefore, the SiO₂@PS foam has a great potential application in oily water treatment.

In this paper, waste polystyrene (PS) plastic was used to fabricate alveolate PS foam via a high internal phase Pickering emulsion (HIPPE) which was stabilized by Span 80 and silica particle as a co-Pickering emulsifier in one-step progress.     

Molecular dynamics simulation study of adsorption of anionic–nonionic surfactants at oil/water interfaces

Four anionic–nonionic surfactants with the same headgroups and different units of oxygen ethyl (EO) and oxygen propyl (PO) were adopted to investigate the influence on oil/water interfacial tensions in this article. Molecular dynamics (MD) simulations were conducted to study the interfacial property of the four surfactants. Four parameters were proposed to reveal the effecting mechanism of molecular structure on interfacial tension, which included the interfacial thickness, order parameter of the hydrophobic chain, radial distribution function, and the solvent accessible surface area. In addition, the electrostatic potential of the four surfactants was calculated. The research results indicated that the interface facial mask formed by the surfactants, which contained three EO or three PO units was more stable, and it was easier for the surfactants of six EO or six PO units to form a microemulsion at higher concentrations. The adsorption mechanism of the anionic–nonionic surfactant systems at the oil/water interfaces was supplemented at a molecular level, which provided fundamental guidance for an in-depth understanding of the optimal selection of the surfactants in enhancing oil recovery.

Four anionic–nonionic surfactants with the same headgroups and different units of oxygen ethyl (EO) and oxygen propyl (PO) were adopted to investigate the influence on oil/water interfacial tensions in this article.     

Fabrication of porous polymer coating layers with selective wettability on filter papers via the breath figure method and their applications in oil/water separation

A comb-like amphiphilic polymer (PBTF), composed of hydrophobic backbones and hydrophilic side chains, was employed to grow honeycomb coating layers in situ on a filter paper via directly casting a polymer solution and by the subsequent dynamic breath figure (BF) method. Through regulating the hydrophilic polymer side chain density and the solution concentration, a continuous honeycomb coating layer contouring to the filter paper surface profile, in addition to possessing a water contact angle (WCA) as high as 146°, was successfully fabricated. The present study also finds that increasing the hydrophilic side chain density will turn PBTF into a surfactant-like polymer, and thus, endow the PBTF solution with the capacity of numerous micro–nano-sized water droplets, rather than simply stabilizing the ordered water droplet arrays on the surface of the solution. With vast nano-sized water droplets in it, the once transparent PBTF solution changed into a translucent nano-emulsion, which demonstrates a strong Tyndall effect. While casting such nano-emulsion on a filter paper and then subjecting to the BF process, the polymeric solute takes both nano-emulsion intrinsic nano-sized water droplets and solvent evaporation-induced water droplets as templates and self-assembles into a bird-nest-like three-dimensional porous microstructure, which possesses micro–nano-sized communicating pores. By regulating the water content in the nano-emulsion, the bird-nest-like structure can be uniformly formed on the surface of the filter paper, which revealed a WCA of 152°. The coated filter papers possess selective wettability, and meanwhile, maintain the inherent permeability of the substrates, which therefore can be directly utilized as oil/water separation materials.

A comb-like amphiphilic polymer composed of hydrophobic backbones and hydrophilic side groups, was employed to in situ grow honeycomb coatings on filter paper via directly polymer solution casting and by the subsequent dynamic breath figure method.     

Superhydrophobic and superoleophilic graphene aerogel for adsorption of oil pollutants from water

Three-dimensional graphene based materials with superhydrophobic/superoleophilic attributes are highly desirable for water treatment. The graphene aerogel (GA) was prepared by hydrothermal reaction of the graphene oxide (GO) solution in the presence of dopamine followed by freeze-drying. The subsequent surface modification of GA using fluoroalkylsilane occurred by a vapor–liquid deposition process. The superhydrophobic graphene aerogel (SGA) fabricated from GA exhibits superhydrophobicity and superoleophilicity with the water contact angle of 156.5° and the oil contact angle of 0°. With this property, SGA could selectively adsorb various types of oils/organic solvents from the oil–water mixture. Moreover, the SGA possesses excellent low bulk density (9.6 mg cm⁻³), high absorption capacity (110–230 fold weight gain), and superior adsorption recyclability. With all these desirable features, the SGA is a promising candidate for oil-polluted water remediation.

SGA with superhydrophobic and oleophilic properties was prepared from a PDA functionalized graphene aerogel via a hydrothermal method and subsequent hydrophobic modification using fluoroalkylsilane through vapor–liquid deposition.     

Extraction of essential oil from Zingiber officinale and statistical optimization of process parameters

The main objective of this study is to investigate the effect of process extraction variables (extraction time, volume of solvent, weight of sample) on the production of essential oil from ginger rhizome using Response Surface Methodology (RSM). A gas chromatography-mass spectrometry (GC-MS) method was employed to obtain the essential oil concentration in percentage (%) area. The RSM indicated that the weight of the sample had a major linear effect on the oil recovery while the extraction time had a major quadratic effect on the essential oil concentration in % area. The highest oil recovery and essential oil concentration in % area were 15.2% and 22.64%, respectively. The best operation conditions for the oil recovery were 4 hours of extraction time, 750 mL volume of methanol and 30 g weight of sample. The best operation conditions for the essential oil concentration in % area were 5 hours of extraction time, 500 mL volume of methanol and 30 g weight of sample.

The main objective of this study is to investigate the effect of process extraction variables (extraction time, volume of solvent, weight of sample) on the production of essential oil from ginger rhizome using Response Surface Methodology (RSM).     

Lung water and alveolar flooding on gas exchange in two models of pulmonary edema

We studied the factors affecting gas exchange in ten anesthetized dogs with pulmonary edema. Different degrees of alveolar flooding and different amounts of lung water (Wdl in g/g dry lung) were produced in two groups of animals: (1) the hydrostatic edema group (n = 5), in which pulmonary edema was produced by massive crystalloid infusion (Wdl ranged from 5.11 ± 0.11 g to 15.18 ± 3.71 g), and (2) the permeability edema group (n = 5), in which pulmonary edema was produced by slow infusion of oleic acid (Wdl ranged from 6.92 ± 1.02 g to 9.63 ± 1.05 g). Wdl was determined postmortem by gravimetric method. Gas exchange was estimated by the multiple inert gas elimination technique after 120 minutes of edema formation, represented by the venous admixture (Qva/Qt)IG%, which was calculated from the amount of blood flow to the shunt and low V/Q regions. At the end of the experiments, 30 random core samples were obtained from the frozen lungs and stained with hematoxylin and eosin. The degree of alveolar flooding in each sample was quantified with a scoring system by two independent observers. The data show that (Qva/Qt)IG% increases as Wdl increases in both groups, but there is consistently more alveolar flooding in the permeability edema group. The degree of alveolar flooding does not exert a significant influence on the outcome of gas exchange and (Qva/Qt)IG% is comparable in both groups when the amounts of lung water are similar.