Supercritical Carbon Dioxide Processing Research Articles

Enzyme activity and nutritional profile of different-sized carrot cubes treated with supercritical carbon dioxide

This study evaluated changes in the enzyme activity, color, carotenoids, sugar profile, individual phenolic compounds, and antioxidant capacity of supercritical carbon dioxide (SCCD)-treated carrot cubes of different sizes (1 cm and 2 cm). Results demonstrated that SCCD reduced the activities of polyphenol oxidase (PPO) and peroxidase (POD) more in 1 cm carrot cubes than in 2 cm carrot cubes. Nevertheless, the a* , b* , and ∆E values of 1 cm SCCD-treated were enhanced compared to 2 cm SCCD-treated samples. The carotenoids, phenolic compounds, and antioxidant capacity of 1 cm SCCD-treated samples were increased under moderate processing conditions. In contrast, the nutritional composition in 1 cm SCCD-treated samples was lower than in 2 cm SCCD-treated samples at harsh processing conditions. The principal component and correction analysis displayed a visual variation between the enzyme activities and nutritional composition of 1 cm and 2 cm carrot cubes after SCCD processing. According to the results above, 1 cm carrot cubes processed with SCCD at 10 MPa, 35 ℃, and 45 min are the most effective at preserving fresh-cut carrots with relatively high enzyme inactivation and the highest retention of bioactive compounds. This work provides a more comprehensive theoretical basis for optimizing SCCD processing for fresh-cut carrots and recommendations for industrial production.

Multi-criteria assessment and optimization of a biomass-based cascade heat integration toward a novel multigeneration process: Application of a MOPSO method

In this study, a novel biomass-driven cascade heat integration scheme is devised, encompassing combined cooling, heating, and power generation, with a unique focus on the production of a secondary product (freshwater). The process commences with the establishment of a biomass digester, yielding biogas fuel to kickstart the integrated system. Subsequently, the utilization of a gas turbine cycle is introduced, and its waste heat is efficiently harnessed through a supercritical carbon dioxide process, a double-effect refrigeration cycle, and a heating terminal. Additionally, a modified organic Rankine cycle is incorporated to recover heat from the supercritical carbon dioxide process, while reverse osmosis desalination forms an integral part of the equipment lineup. The entire system is rigorously evaluated from both thermodynamic and economic standpoints, undergoing optimization across five distinct scenarios. A multi-objective particle swarm optimization approach, featuring two decision-making algorithms, is deployed in this optimization process. The primary objective is exergetic efficiency, while the secondary objectives encompass net output power, cooling, heating, sum unit cost of products, and net present value, each considered individually. The results of the study reveal that the highest attainable optimal exergy efficiency stands at 38.54 % when the secondary objective is net output power. Furthermore, the optimal values for the secondary objectives are determined to be 41112.59 kW, 1383.75 kW, 28413.97 kW, 18.72 $/GJ, and 75.17 M$, respectively. These findings underscore the potential of the proposed biomass-driven cascade heat integration system in achieving efficient and sustainable energy generation while simultaneously producing valuable secondary products.

Non-Thermal Supercritical Carbon Dioxide Processing Retains the Quality Parameters and Improves the Kinetic Stability of an Araticum Beverage Enriched with Inulin-Type Dietary Fibers.

Fruit-based beverages have been considered excellent food vehicles for delivering prebiotics. However, the conventional thermal processes currently used to microbiologically and enzymatically stabilize these products may cause significant losses in their sensory, physicochemical, nutritional, and bioactive characteristics. Thus, in this study, we evaluate the effect of different levels of pressure (8, 15, and 21 MPa) and temperature (35 and 55 °C) on the characteristics of an inulin-enriched araticum beverage processed with non-thermal supercritical carbon dioxide (SC-CO2) technology. The temperature showed a significant effect on total soluble solids, pH, particle size distribution, and kinetic stability. In contrast, pressure affected only the particle size distribution. The interaction between pressure and temperature influenced the total soluble solids, pH, and particle size distribution. Color parameters, ζ-potential, and glucose and fructose contents were not modified after all SC-CO2 treatments. Moreover, the SC-CO2 treatments preserved the inulin molecular structure, thus maintaining its prebiotic functionality. Overall, the SC-CO2 treatment did not alter the sensory, nutritional, and functional quality of the beverage, while improving its physical stability during storage. Therefore, non-thermal SC-CO2 treatment can be an alternative to current conventional processes for stabilizing inulin-enriched fruit-based beverages.

Controlled Release of Flurbiprofen from 3D-Printed and Supercritical Carbon Dioxide Processed Methacrylate-Based Polymer.

The ability to engineer and predict drug release behavior during treatment is critical to the design and implementation of effective drug delivery systems. In this study, a drug delivery system consisting of a methacrylate-based polymer and flurbiprofen was studied, and its release profile in a controlled phosphate-buffered saline solution was characterized. The polymer, which was 3D printed and processed in supercritical carbon dioxide under different temperature and pressure settings, showed sustained drug release over a prolonged period. A computer algorithm was used to determine the drug release time duration before reaching steady state and the maximum drug release at steady state. Several empirical models were applied to fit the release kinetic data to gain information about the drug release mechanism. The diffusion coefficients for each system were also estimated using Fick's law. Based on the results, the influence of supercritical carbon dioxide processing conditions on the diffusion behavior is interpreted, providing insights into the effective and tunable design of drug delivery systems for targeted treatment specifications.

Process of Zanthoxylum armatum DC. oil by a novel low-temperature continuous phase transition extraction: Evaluation of aroma, pungent compounds and quality

Zanthoxylum armatum DC. (ZAD) oil is one of the most popular seasonings for its unique flavor and numbing taste. However, aromatic and pungent components are easily affected by extraction process. In this study, a novel low-temperature continuous phase transition process (CPTP) was applied to extract ZAD oil, and the flavor and quality of oil were compared with the those of products obtained from fried process (FP), fresh squeezed process (FSP) and supercritical carbon dioxide process (SCDP) using Gas Chromatography-Mass Spectrometry/Olfactometry and UPLC-DAD-ESI-Q-TOF-MS/MS. The outcome demonstrated that the oil preserved higher volatile aroma components from SCDP and CPTP (606.073 mg/g and 194.905 mg/g, respectively). It's interesting to note that the majority of the alkyl components were only present in the ZAD oil created using CPTP, which further preserved the original makeup of the fragrance components of ZAD. Four ZAD oil had considerably different pungent compounds, with SCDP having the greatest concentration (16697.78 g/mL), followed by CPTP (6425.66 g/mL), FP (2662.6 g/mL), and FSP (719.69 g/mL). Physicochemical properties analysis indicated that unsaturated fatty acid content was highest for FSP oil (91.97%). Overall, as a fresh and effective extraction technique, CPTP may be appropriate for the extraction of natural fragrance components.

Extraction of polyhydroxyalkanoate from activated sludge using supercritical carbon dioxide process and biopolymer characterization

Polyhydroxyalkanoates (PHA) are biodegradable polymers and have the potential to substitute with fossil-fuel based polymers since they have similar properties. Many studies on the production of PHA have been conducted, but the extraction/purification processes have received less attention. Mostly, solvent extraction has been studied, and the effect of different solvent types on the separation processes have been investigated. A better extraction method for PHA makes it a feasible alternative to fossil-fuel based polymers. In this study, a new protocol for the extraction of PHA from activated sludge by supercritical carbon dioxide disruption (sCO2) and biopolymer recovery from disrupted cells were proposed. Extraction experiments were carried out with sCO2 at different pressures, temperatures, times, biomass amounts, and modifier volumes. The operation yield was expressed based on the polyhydroxybutyrate (PHB) release efficiency. The biomass for the extraction experiments was obtained from a PHA production reactor where activated sludge was fed with anaerobically pretreated yeast industry wastewater. 80 % PHB releasing efficiency was achieved by disturbing 2 g of biomass at a density of 57 g/L (biomass/volume) with sCO2 at 200 bar pressure for 15 min at 40 °C. The PHB purity and molecular weight (Mv) of biopolymers were 80 % and 0.27•106 respectively. The use of methanol as a modifier during the sCO2 disruption increased the Mv to 0.37•106. Characterization studies by Fourier transform infrared spectroscopy (FTIR) and thermal degradation analysis (TGA) demonstrated that the biopolymer recovered with this extraction protocol was comparable to commercial PHB. As a clear advantage over the other extraction protocols; operationally fast and simple extraction procedure was achieved.

Nanocarrier of Pin1 inhibitor based on supercritical fluid technology inhibits cancer metastasis by blocking multiple signaling pathways.

Cancer metastasis is the primary cause of all cancer-related deaths due to the lack of effective targeted drugs that simultaneously block multiple signaling pathways that drive the dissemination and growth of cancer cells. The unique proline isomerase Pin1 activates numerous cancer pathways, but its role in cancer metastasis and the inhibitory efficacy of Pin1 inhibitors on cancer metastasis are unknown. Moreover, the applicability of Pin1 inhibitor-all-trans retinoic acid (ATRA) is limited due to its several drawbacks. Herein, uniform ATRA-loaded polylactic acid-polyethylene glycol block copolymer nanoparticles (ATRA-NPs) with high encapsulation efficiency, good cellular uptake, excellent controlled release performance and pharmacokinetics are developed using supercritical carbon dioxide processing combined with an optimized design. ATRA-NPs exhibited excellent biosafety and significant inhibition on the growth and metastasis of hepatocellular carcinoma. Pin1 played a key role in cancer metastasis and was the main target of ATRA-NPs. ATRA-NPs exerted their potent anti-metastatic effect by inhibiting Pin1 and then simultaneously blocking multiple signaling pathways and cancer epithelial-mesenchymal progression. Since ATRA-NPs could effectively couple the inhibition of cancer cell dissemination with cancer growth, it provided a novel therapeutic strategy for efficiently inhibiting cancer metastasis.

Dissolution Improvement of Progesterone and Testosterone via Impregnation on Mesoporous Silica Using Supercritical Carbon Dioxide

Progesterone (PRG) and testosterone (TST) were impregnated on mesoporous silica (ExP) particles via supercritical carbon dioxide (scCO2) processing at various pressures (10–18 MPa), temperatures (308.2–328.2 K), and time (30–360 min). The impact of a co-solvent on the impregnation was also studied at the best determined pressure and temperature. The properties of the drug embedded in silica particles were analysed via gas chromatography (GC), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray diffraction (XRD), differential scanning calorimetry (DSC), and nitrogen adsorption. An impregnation of 1 to 82 mg/g for PRG and 0.1 to 16 mg/g for TST was obtained depending on the processing parameters. There was a significant effect of pressure, time, and co-solvent on the impregnation efficiency. Generally, an increase in time and pressure plus the use of co-solvent led to an improvement in drug adsorption. Conversely, a rise in temperature resulted in lower impregnation of both TST and PRG on ExP. There was a substantial increase in the dissolution rate (> 90% drug release within the first 2 min) of both TST and PRG impregnated in silica particles when compared to the unprocessed drugs. This dissolution enhancement was attributed to the amorphisation of both drugs due to their adsorption on mesoporous silica.Graphical

Thermodynamic behavior and crystal structure of polypropylene treated with supercritical carbon dioxide

Abstract Controlling temperature and pressure during the supercritical carbon dioxide (scCO2) process can change the mount of CO2 entered in polypropylene (PP) phase, thereby changing the mechanical properties of materials. The effect of scCO2 treatment on the crystallization behavior is different in the semi-molten and molten states. This study investigates the PP treated with scCO2 near the melting point and at various pressures, and explores the effects of temperature and pressure on the crystal structure, lamellar structure, and thermodynamic properties of PP. The results show that at a melting temperature of 165 °C, scCO2 can enhances the ability of PP molecules to makes the PP crystal region more regular, and forms larger microcrystals and lamellae. Additionally, increasing the pressure can make more CO2 enter the PP crystal region and further improve the regularity of the crystal. At a semi-melting temperature of 155 °C, scCO2 is primarily in the amorphous region because it is difficult to enter the PP crystal region. Even if increasing the pressure, it has little effect on the crystal size and lamellar thickness of PP. The research has significant implications for developing and utilizing scCO2 to remove ash from materials.

Enzyme Activity and Physiochemical Properties of Flour after Supercritical Carbon Dioxide Processing.

The objectives of this study were to inactivate the enzymes α-amylase, lipase, protease, and peroxidase in flour with supercritical carbon dioxide (scCO2), and to optimize the enzymatic treatment conditions. Enzyme inactivation is important, due to the undesirability of certain flour enzymes that cause adverse reactions during storage as unpleasant rancidity of flour, and, at the same time, reduce the shelf life of flour. Therefore, crude enzymes and flour were initially exposed to scCO2 to determine the effect on specific enzyme activity under appropriate conditions. The activity of the unwanted enzymes lipase and peroxidase decreased under optimal process conditions of scCO2 exposure, lipase by 30%, and peroxidase by 12%, respectively. It was discovered that the inactivation of enzymes in wheat flour occurred, where, at the same time, this sustainable method allows the regulation of enzyme activity in the baking process. Afterwards, the effect of scCO2 on the physicochemical properties of flour, morphological changes on starch granules, and content of total lipids was studied. In scCO2-treated white wheat flour, the fat content decreased by 46.15 ± 0.5%, the grain structure was not damaged, and the bread as the final product had a lower specific surface volume. Therefore, this could be a promising technology for flour pretreatment, potentially impacting the prolonging of its shelf-life.

Preparation of Solid Dispersions of Simvastatin and Soluplus Using a Single-Step Organic Solvent-Free Supercritical Fluid Process for the Drug Solubility and Dissolution Rate Enhancement.

The study was designed to investigate the feasibility of supercritical carbon dioxide (scCO2) processing for the preparation of simvastatin (SIM) solid dispersions (SDs) in Soluplus® (SOL) at temperatures below polymer’s glass transition. The SIM content in the SDs experimental design was kept at 10, 20 and 30% to study the effect of the drug–polymer ratio on the successful preparation of SDs. The SIM–SOL formulations, physical mixtures (PMs) and SDs were evaluated using X-ray diffraction (XRD), differential scanning calorimetry (DSC), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), and dissolution studies. The scCO2 processing conditions and drug–polymer ratio were found to influence the physicochemical properties of the drug in formulated SDs. SIM is a highly crystalline drug; however, physicochemical characterisation carried out by SEM, DSC, and XRD demonstrated the presence of SIM in amorphous nature within the SDs. The SIM–SOL SDs showed enhanced drug dissolution rates, with 100% being released within 45 min. Moreover, the drug dissolution from SDs was faster and higher in comparison to PMs. In conclusion, this study shows that SIM–SOL dispersions can be successfully prepared using a solvent-free supercritical fluid process to enhance dissolution rate of the drug.

Enhancing resistant starch content in brown rice using supercritical carbon dioxide processing

AbstractDietary fiber and resistant starch (RS) play a key role in suppressing the increase in blood glucose levels. Whole grains such as brown rice (BR) which have a higher content of dietary fiber and important nutrients, are common products used for the maintenance of human health. The higher RS content in BR is suggested to contribute significantly to blood glucose level maintenance in cooperation with dietary fiber. We aimed to enhance the RS levels in BR using supercritical carbon dioxide (scCO2) processing which is typically undertaken by the reactor packed with BR and filled carbon dioxide in a state of supercritical fluids developed with above critical temperature and pressure, and a suitable operating duration as an alternative to conventional methods. This innovative process expectedly enhanced the RS content, promoted gelatinization, and eliminated the foul odors causing appetizing control. In addition, this processing method is highly effective for the removal of pollutions such as pesticides and inactivation of microbial contaminants in food. Therefore, scCO2 processing is a promising alternative to conventional methods.Practical ApplicationProcessing RS in cereals using scCO2 is an innovative alternative to conventional processes such as heat‐moisture treatment and annealing, autoclaving and retrogradation cycles, high hydrostatic pressure, and extrusion that are commonly used to promote RS formation in food products to improve human health and consequently contributes to the control of blood glucose levels after a meal. The innovative scCO2 process is considerably simple, easily operable, and environmentally friendly and safe due to the use of nontoxic CO2 as a solvent. This process has great potential for application in the extraction of pesticides and fats and the inactivation of microbes in food products. Therefore, scCO2 processing will be useful as a food processing method that helps maintain human health.

Extraction of Citrullus colocynthis L. seed oil by supercritical carbon dioxide process using response surface methodology (RSM) and artificial neural network (ANN) approaches

In this research work, response surface methodology and artificial neural network were applied to Citrullus colocynthis seed oil extracted to optimize its oil yield (%) and antioxidant activities (IC50) by supercritical−CO2 extraction process and then compared. A Box Behnken design, with three-levels and five independent variables (pressure, extraction temperature, ethanol concentration, flow rate of CO2, and particle size), was also investigated. Besides, a backpropagation training-ANN with five inputs, one hidden layer (6 neurons) and one output, was selected as the best architectural topology of each tested response. Furthermore, the obtained data have revealed that the extraction pressure represents the most significant factor in oil yield (Y1) and the antioxidant activities (IC50) (Y2). Therefore, the optimum conditions, obtained by the model of artificial neural network, were as follow: pressure 275 bar, extraction temperature 72.4 °C, ethanol concentration 8.50 %, flow rate of supercritical−CO2 7.4 g/min, and particle size of 0.55 mm. Under these ultimate conditions, the oil yield (Y1) and the antioxidant activities (Y2) were 38.12 % and 0.17 mg/mL, respectively, which accords well with the values predicted by the ANN-model. Thus, although response surface methodology is likely to demonstrate the interaction effects between the independent variables of SC−CO2 extraction process, artificial neural network can reliably boost the SC−CO2 process with better estimative capabilities. Generally, the most elevated levels of bioactive compounds and the strongest antioxidant activities of Citrullus colocynthis SC−CO2 seed oils suggest that it could be economically used as appreciated natural products for chemical, cosmetic and pharmaceutical applications.

Retraction: Synthesis of Cu2 ZnSnS4 Micro- and Nanoparticles via a Continuous-Flow Supercritical Carbon Dioxide Process.

Retraction: Synthesis of Cu2 ZnSnS4 Micro- and Nanoparticles via a Continuous-Flow Supercritical Carbon Dioxide Process.

Surface morphology and drug loading characterization of 3D-printed methacrylate-based polymer facilitated by supercritical carbon dioxide

Polymers have been shown to have viable applications in the biomedical field, from controlled drug delivery systems to biological implants. The preparation and processing of polymers into bio-systems have nevertheless encountered some technical challenges in part customization and adverse effects to the human body functions and recovery. This study proposes the utilization of 3D printing technology and supercritical carbon dioxide (scCO2) processing to deliver a drug-impregnated polymeric material system which can be engineered and tuned to suit a particular implantation procedure and dramatically improve patient outcomes. In this work, an acrylate-based polymer is 3D-printed using stereolithography, then impregnated with flurbiprofen drug using scCO2. Drug loading above 24 % by mass is achievable under the tested conditions. The correlation of drug loading and material surface roughness with different process parameters, including 3D printing layer thickness, scCO2 processing temperature, pressure and treatment time, are investigated and empirically modeled using the linear regression methods.

Efficacy of Neem Kernel Bioactives Extracted using Supercritical Fluid Carbon Dioxide on Selected Dermatophytes and Foodborne Pathogens

Neem seed kernel was subjected to supercritical fluid carbon dioxide (SCF) process and evaluated for the inhibition of selected dermatophytes such as Candida albicans, Candida tropicalis, Candida parapsilosis, Trichophyton rubrum, Trichophyton mentagrophytes. The extraction was carried out by SCF-CO2 at 300 bar 50 °C with and without entrainer (30 % methanol and acidified methanol). Results showed that the inhibition of the growth of all the dermatophytes is maximum in the extract obtained at 300 bar 50 °C with methanol (SCF-Me) followed by 300 bar 50 °C without methanol (SCF). The acidified SCF (SCF-MeA) extract did not show any remarkable inhibition. Of the dermatophytes, SCF-Me showed the inhibition against Candida parapsilosis of 18.46±0.25 mm compared to Candida albicans 16±0.26 mm, whereas the methanol control exhibited 10±0.3 mm inhibition. Out of the two fungal organisms, SCF-Me inhibited the growth of Trichophyton rubrum and Trichophyton mentagrophytes at 21.53±0.23 mm and 18.1±0.1 mm respectively. The extracts were also evaluated for its inhibition against the foodborne pathogens (bacteria, fungi, and yeast). The SCF-Me extract showed maximum inhibition against Pseudomonus aeroginosa (27.26±0.25) compared to Bacillus subtilis (24.36±0.35) at the concentration of 70mg. In fungus, Aspergillus ochraceus (16.7±0.60) was maximum when compared to Aspergillus niger (15.2±0.43) and yeast exhibited the inhibition of 15.93±0.20 at the concentration of 80mg. The dermatophytic and antimicrobial activity of the SCF-Me extract is due to the presence of higher amount of triterpenoinds such as Azadirachtin (50.7 %), 6-deacetyl nimbin (0.14 %), Nimbin (0.08 %), Salannin (1.83 %) and Epoxy azadiradione (1.58 %) which were confirmed by liquid chromatography and mass spectroscopy (LC-MS).

Myristic Acid Coated Protein Immobilised Mesoporous Silica Particles as pH Induced Oral Delivery System for the Delivery of Biomolecules.

Solid core drug delivery systems (SCDDS) were prepared for the oral delivery of biomolecules using mesoporous silica as core, bovine haemoglobin (bHb) as model drug and supercritical fluid (SCF) processing as encapsulation technique. The use of organic solvents or harsh processing conditions in the development of drug delivery systems for biomolecules can be detrimental for the structural integrity of the molecule. Hence, the coating on protein-immobilised particles was performed via supercritical carbon dioxide (scCO2) processing at a temperature lower than the melting point of myristic acid (MA) to avoid any thermal degradation of bHb. The SCDDS were prepared by bHb immobilisation on mesoporous silica followed by myristic acid (MA) coating at 43 °C and 100 bar in scCO2. bHb-immobilised silica particles were also coated via solvent evaporation (SE) to compare the protein release with scCO2 processed formulations. In both cases, MA coating provided required enteric protection and restricted the bHb release for the first two hours in simulated gastric fluid (SGF). The protein release was immediate upon the change of media to simulated intestinal fluid (SIF), reaching 70% within three hours. The release from SCF processed samples was slower than SE formulations, indicating superior surface coverage of MA on particles in comparison to the SE method. Most importantly, the protein conformation remained unchanged after the release from SCDDS as confirmed by circular dichroism. This study clearly demonstrates that the approach involving protein immobilisation on silica and scCO2 assisted melt-coating method can protect biomolecules from gastric environment and provide the required release of a biologic in intestine without any untoward effects on protein conformation during processing or after release.

Synthesis of (sub)microcrystals of dinuclear terbium(III) carboxylate (Hpiv)6Tb2(piv)6 and polymeric terbium(III) carboxylate {Tb(piv)3}n in supercritical carbon dioxide. Photoluminescence and magnetic properties

Supercritical fluid micronization by rapid expansion of supercritical solutions setup using supercritical carbon dioxide as a fluid and the dinuclear complex (Hpiv)6Tb2(piv)6 (1) as the starting compound allows the preparation of either the single-phase dinuclear complex (Hpiv)6Tb2(piv)6 (1a) or the coordination polymer {Tb(piv)3}n (2a, 2b, 2c) as (sub)microcrystals with a controlled size depending on the processing parameters. It was shown that {Tb(piv)3}n (2) can in principle be synthesized by supercritical carbon dioxide processing as polycrystalline particles with different morphologies. A decrease in the size of polycrystalline particles (aggregates) of 1 and 2 and an increase in the fraction of defects in the crystal structure, respectively, lead to an increase in the degree of photoluminescence quenching at these defects and a change in magnetic properties of 1.

Changes in the morphology of poly( l ‐lactide‐ ran ‐δ‐valerolactone) following supercritical carbon dioxide processing

Changes in the morphology of poly( <scp>l</scp> ‐lactide‐ <i>ran</i> ‐δ‐valerolactone) following supercritical carbon dioxide processing

Effect of silane functionalized graphene prepared by a supercritical carbon dioxide process on the barrier properties of polyethylene terephthalate composite films

In this work, a simple and eco-friendly strategy to modify graphene nanoplatelets (GNs) with different silane coupling agents using a supercritical carbon dioxide (Sc-CO2) process has been presented, and effect of the modified GNs on the oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) of GN/PET composite films was studied. FT-IR, SEM, EDX and TG results indicated that Sc-CO2 process was an effective strategy to modify GNs with silane coupling agents. Addition of the modified GNs into PET matrix could greatly decrease the OTR and WVTR values of the GNs/PET composite films, and the WVTR of GNs560/PET composite film and OTR of GNs550/PET composite film were respectively decreased about 90.08% and 58.04%, as compared to those of GNs/PET composite film. It is found that the gas barrier property of GN/PET composites was attributed to not only the tortuous path effect caused by GNs themselves and the interfacial interaction, but also the affinity of binding bonds between GNs and the polymer to the gas molecules. It is believed that this work provided a strategy to design and prepare CN/polymer composites with high barrier properties.