Enhanced Desulfurization Performance of ZIF-8/PEG MMMs: Effect of ZIF-8 Particle Size.

Constructing efficient and continuous transport pathways in membranes is a promising and challenging way to achieve the desired performance in the pervaporation process. The incorporation of various metal-organic frameworks (MOFs) into polymer membranes provided selective and fast transport channels and enhanced the separation performance of polymeric membranes. Particle size and surface properties are strongly related to the random distribution and possible agglomeration of MOFs particles, which may lead to poor connectivity between adjacent MOFs-based nanoparticles and result in low-efficiency molecular transport in the membrane. In this work, ZIF-8 particles with different particle sizes were physically filled into PEG to fabricate mixed matrix membranes (MMMs) for desulfurization via pervaporation. The micro-structures and physi-/chemical properties of different ZIF-8 particles, along with their corresponding MMMs, were systematically characterized by SEM, FT-IR, XRD, BET, etc. It was found that ZIF-8 with different particle sizes showed similar crystalline structures and surface areas, while larger ZIF-8 particles possessed more micro-pores and fewer meso-/macro-pores than did the smaller particles. ZIF-8 showed preferential adsorption for thiophene rather than n-heptane molecules, and the diffusion coefficient of thiophene was larger than that of thiophene in ZIF-8, based on molecular simulation. PEG MMMs with larger ZIF-8 particles showed a higher sulfur enrichment factor, but a lower permeation flux than that found with smaller particles. This might be ascribed to the fact that larger ZIF-8 particles provided more and longer selective transport channels in one single particle. Moreover, the number of ZIF-8-L particles in MMMs was smaller than the number of smaller ones with the same particle loading, which might weaken the connectivity between adjacent ZIF-8-L nanoparticles and result in low-efficiency molecular transport in the membrane. Moreover, the surface area available for mass transport was smaller for MMMs with ZIF-8-L particles due to the smaller specific surface area of the ZIF-8-L particles, which might also result in lower permeability in ZIF-8-L/PEG MMMs. The ZIF-8-L/PEG MMMs exhibited enhanced pervaporation performance, with a sulfur enrichment factor of 22.5 and a permeation flux of 183.2 g/(m-2·h-1), increasing by 57% and 389% compared with the results for pure PEG membrane, respectively. The effects of ZIF-8 loading, feed temperature, and concentration on desulfurization performance were also studied. This work might provide some new insights into the effect of particle size on desulfurization performance and the transport mechanism in MMMs.

GO-Based Membranes for Desalination.

Graphene oxide (GO), owing to its atomic thickness and tunable physicochemical properties, exhibits fascinating properties in membrane separation fields, especially in water treatment applications (due to unimpeded permeation of water through graphene-based membranes). Particularly, GO-based membranes used for desalination via pervaporation or nanofiltration have been widely investigated with respect to membrane design and preparation. However, the precise construction of transport pathways, facile fabrication of large-area GO-based membranes (GOMs), and robust stability in desalination applications are the main challenges restricting the industrial application of GOMs. This review summarizes the challenges and recent research and development of GOMs with respect to preparation methods, the regulation of GOM mass transfer pathways, desalination performance, and mass transport mechanisms. The review aims to provide an overview of the precise regulation methods of the horizontal and longitudinal mass transfer channels of GOMs, including GO reduction, interlayer cross-linking, intercalation with cations, polymers, or inorganic particles, etc., to clarify the relationship between the microstructure and desalination performance, which may provide some new insight regarding the structural design of high-performance GOMs. Based on the above analysis, the future and development of GOMs are proposed.

Electron structure modulation and bicarbonate surrounding enhance Fenton-like reactions performance of Co-Co PBA.

Although several strategies have been developed to improve the efficiency of heterogeneous Fenton-like reactions, investigating the relationship among the electronic properties of the catalyst surface, the complex water matrix and catalytic activity remains challenges. Herein, the electron density of the active site Co(II) in Co Prussian blue analogs (Co-PBAs) is proved to be modulated by the anion source method. The elevated electron density of Co(II) and the higher metallicity of the catalyst lead to an increase in electron transport efficiency as revealed by X-ray photoelectron spectra (XPS), Fourier transform infrared spectroscopy (FT-IR), and density functional theory (DFT) calculations. Furthermore, the negative shift of the D-band center of Co(II) can effectively release intermediates to avoid catalyst poisoning. Bicarbonate has been demonstrated to activate peroxymonosulfate (PMS) by weakening the peroxide bond. Its activation mechanism involves free radical mechanism and non-radical mechanism: the first step is the generation of HCO4-, then it is further hydrolyzed to generate •OH and 1O2, and the other is HCO4- interact with Co(III) to form Co(IV)=O. In addition, the degradation pathways of target contaminants p-nitrophenol and toxicity verification of intermediate products have been investigated. This study provides guidance for the research of Fenton-like reactions.

Preparation of lignosulfonate-based nanofiltration membranes with improved water desalination performance.

Pulping and papermaking generate large amounts of waste in the form of lignosulfonates which have limited valorized applications so far. Herein, we report a novel lignosulfonate-based nanofiltration membrane, prepared by using polyethylenimine (PEI) and sodium lignosulfonate (SL) via a layer-by-layer (LbL) self-assembly. As a low-cost and renewable natural polyelectrolyte, SL is selected to replace the synthetic polyelectrolyte commonly used in the conventional LbL fabrication for composite membranes. The prepared LbL (PEI/SL)7 membranes were crosslinked by glutaraldehyde (GA) to obtain (PEI/SL)7-GA membranes with compact selective layer. We characterized (PEI/SL)7 and (PEI/SL)7-GA membranes to study the chemical compositions, morphologies, and surface hydrophilicity. To improve the nanofiltration performances of the (PEI/SL)7-GA membranes for water desalination, we investigated the effects of the crosslinking time, GA concentration and the NaCl supporting electrolyte on membrane structure and performance. The optimized (PEI/SL)7-GA membrane exhibited a permeating flux up to 39.6 L/(m2·h) and a rejection of 91.7% for the MgSO4 aqueous solution 2.0 g/L concentration, showing its promising potential for water desalination. This study provides a new approach to applying the underdeveloped lignin-based biomass as green membrane materials for water treatment.

Humic Acid Removal from Water with PAC-Al30: Effect of Calcium and Kaolin and the Action Mechanisms.

Polyaluminum chloride with a dominant species of Al30 (PAC-Al30) was prepared in laboratory and used for humic acid (HA) removal from water. The action properties and mechanisms of PAC-Al30, HA, calcium, and kaolin were tested and discussed. The results showed that the existence of calcium or kaolin contributed to the HA removal when the PAC-Al30 dosage was deficient and had no obvious effect when the amount of PAC-Al30 was sufficient. When the PAC-Al30 dosage was 0.01 and 0.02 mmol/L, the HA removal rate was increased by 66.59 and 42.20%, respectively, with a calcium concentration of 2.0 mmol/L, or increased by 53.31 and 40.92%, respectively, with the kaolin particle concentration of 150 mg/L. Calcium could compress the double electrical layers or complex with HA to neutralize a part of the surface negative charge of HA, but could not make the water system reach its isoelectric point. The mechanisms of calcium and kaolin's promoting coagulation effect were adsorption neutralization and collision aggregation respectively, but these actions were much weaker than that of PAC-Al30 with HA. The adsorption neutralization capacity of PAC-Al30 was calculated to be nearly 60 times than that of calcium, and the higher γ value of calcium modified by the Sips equation may indicate that the adsorption or neutralization sites of calcium on HA were pickier than PAC-Al30.

Poly(vinyl alcohol)-Modified Membranes by Ti3C2T x for Ethanol Dehydration via Pervaporation.

In this paper, PVA/Ti3C2T x mixed matrix membranes (MMMs) were prepared by mixing the synthesized Ti3C2T x with the PVA matrix, and the pervaporation (PV) performance of the ethanol-water binary system was tested. The morphology, structural properties, and surface characteristics of the membranes were investigated by scanning electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, degree of swelling, and water contact angle. The PVA/Ti3C2T x MMMs exhibit excellent compatibility and swelling resistance. Moreover the effects of the Ti3C2T x filling level, feed concentration, and operating temperature on the ethanol dehydration performance were systematically studied. The results demonstrated that the separation factor of PVA/Ti3C2T x MMMs was significantly increased because of Ti3C2T x promoting the cross-linking density of the membrane. Specifically, the membrane showed the best PV performance when Ti3C2T x loading was 3.0 wt %, achieving a separation factor of 2585 and a suitable total flux of 0.074 kg/m2 h for separating 93 wt % ethanol solution at 37 °C.

Improved Desulfurization Performance of Polyethyleneglycol Membrane by Incorporating Metal Organic Framework CuBTC.

In this paper, copper benzene-1,3,5-tricarboxylate (CuBTC) was incorporated into polyethylenglyol (PEG) to prepare a mixed matrix membrane (MMM) for pervaporation desulfurization. The characterization results showed that the prepared CuBTC particles had an ideal octahedral shape and micropores. The Cu2+ in CuBTC interacts with thiophene via π-complexation, thus enhancing the separation performance of the hybrid membranes. The effect of CuBTC content and the operating condition on the pervaporation performance of the MMMs was investigated. An optimal pervaporation separation performance was acquired with a permeation flux of 2.21 kg/(m2·h) and an enrichment factor of 8.79, which were increased by 100% and 39% compared with the pristine PEG membrane. Moreover, the CuBTC-filled PEG membrane showed a good stability in the long-term desulfurization under a high operating temperature of 75 °C for five days.

High-poly-aluminum chloride sulfate coagulants and their coagulation performances for removal of humic acid.

High-poly-aluminum chloride sulfate (HPACS) coagulants with different [SO4 2-]/[Al3+] molar ratio (S) were prepared and proved to have high coagulation efficiency for the removal of humic acid and strong stability for storage and application. The results showed that the higher the SO4 2- addition, the bigger the aluminum polymerization particles and the more the polymerization Alc existed in the prepared HPACS coagulants. The HPACS exhibited higher coagulation efficiency, a better aging stability and stronger resistance to the change of pH and Ca2+ concentration of raw water than the polyaluminum chloride (PAC) and poly-aluminum chloride sulfate (PACS) reported before. The Sips adsorption neutralization model was established to illustrate the relationship between coagulant dosage and zeta potential of the water system. The adsorption neutralization capacity was proved to be HPACS (S = 0) > HPACS (S = 0.02) > HPACS (S = 0.06) > HPACS (S = 0.10), which was not completely consistent with the coagulation effect of HPACS with different S values and indicated that in addition to adsorption neutralization, actions like bridge-aggregation, precipitation, and sweep-flocculation also played an important role during HPACS coagulation. Moreover, the negative Gibbs free energy indicated that the coagulant adsorption neutralization reaction was a spontaneous process.

Exploiting Giant-Pore Systems of Nanosized MIL-101 in PDMS Matrix for Facilitated Reverse-Selective Hydrocarbon Transport.

Membrane gas separation offers high energy efficiency, easy operation, and reduced environmental impacts for vast hydrocarbon recovery in the petrochemical industry. However, the recovery of real light hydrocarbon mixtures (e.g., olefin/nitrogen) remains challenging for lack of high-performance membranes with sufficient reverse selectivity (large molecules permeate faster) and permeability. Here, we report the incorporation of fine-tuned, giant-pore featured MIL-101 nanocrystals into rubbery polymers to fabricate hybrid membranes, which successfully exploited the giant-pore channels and large sorption volume of the MIL-101 pore system. The synthesized MIL-101/poly(dimethylsiloxane) (PDMS) hybrid membranes demonstrated remarkably simultaneous improvement of gas permeance and separation factor for the model gas mixture propylene/nitrogen. Compared with the pristine PDMS, the propylene permeance and separation factor could be improved by more than 50% by adjusting MIL-101 loading and operating conditions. By consulting molecular simulations and gas sorption analysis, we verified that the giant-pore system of MIL-101 and the elastic PDMS chains exhibited a synergistic effect on improving both hydrocarbon solution and diffusion. Pore properties of MIL-101 contributed favorably to accelerated propylene diffusion in MIL-101 that is 236% faster than that in PDMS. In the meantime, MIL-101 reinforced the hydrocarbon solution additionally to PDMS, which further facilitated hydrocarbon transport.

Preparation of SGO-modified nanofiltration membrane and its application in SO42- and Cl- separation in salt treatment.

The lack of fresh water in the world makes the search for an effective method to decontaminate water an urgent priority. An important step is to remove different multivalent ions in salt treatment. Nanofiltration (NF) has been used for treating water containing different kinds of salts. In this work, sulfonate group-modified graphene oxide (SGO) was prepared, and added during the interfacial polymerization (IP) reaction to prepare SGO-modifiedNF membranes (PA-SGO). The chemical composition, structure and surface properties of PA and PA-SGO membranes were characterized by FT-IR, XPS, SEM, AFM, contact angle and zeta potential measurements. Their water flux, salt rejection and anti-fouling abilities were investigated systematically. The testing results showed that the water flux of PA-SGO (0.03% SGO) was 45.85 LMH under a pressure of 0.2 MPa, and the salt rejection varied in the order of Na2SO4 (98.99%) > MgSO4 (91.25%) > MgCl2 (42.27%) > NaCl (21.96%). An anti-fouling experiment indicated that the PA-SGO membrane had good anti-fouling properties because of its decreased roughness and increased hydrophilicity and electronegativity. The PA-SGO membrane has good potential for use in removing salt ions from water.

Preparation of graphene oxide/poly(vinyl alcohol) composite membrane and pervaporation performance for ethanol dehydration.

Although poly(vinyl alcohol) (PVA) membranes are widely used in solvent dehydration by pervaporation, the separation factor is rather limited. Considering this, novel PVA mixed matrix membranes with graphene oxide (GO) nanosheets were prepared. poly(acrylonitrile) ultrafiltration (PAN) membrane was used as support layer. The PVA/GO composite membranes were characterized by Fourier transform infrared spectroscopy, X-ray diffractometry, scanning electron microscopy, thermogravimetric analysis and water contact angle. We also explored the pervaporation performance of the membrane for ethanol dehydration. GO slightly improves the thermal stability and crystallinity of the composite membranes. In addition, the hydrophilicity of the composite membranes is weakened after GO addition, but the crosslinking degree is increased, resulting a significant increase in the separation factor and a certain decrease in the total flux. With the amount of GO addition increases, the total flux of the PVA/GO composite membrane decreases, while the separation factor increases first and then decreases, and the preferred amount of GO addition is 2.0 wt%. Especially, the separation factor of the composite membranes with 2.0 wt% GO addition could reach 3 059, which is 16 times higher than PVA membranes, with the corresponding permeability flux is 145 g m-2 h-1.

Performance of a pervaporation system for the separation of an ethanol-water mixture using fractional condensation.

Polydimethylsiloxane (PDMS)/polyvinylidene fluoride (PVDF) composite membranes were fabricated and subsequently applied in ethanol recovery from an ethanol-water mixture by pervaporation (PV) using fractional condensation. The effects of feed temperature and feed flow velocity on the pervaporative properties of PDMS/PVDF composite membranes were investigated. Scanning electron microscopy (SEM) results showed that PDMS was coated uniformly on the surface of porous PVDF substrate, and the PDMS separation layer was dense with a thickness of 1.7 µm. Additionally, it was found that with increasing feed temperature, the total flux of the composite membrane increased, whereas the separation factor decreased. As the feed flow velocity increased, the total flux and separation factor increased. Besides, the permeate vapor was condensed by a two-stage fractional condenser maintained at different temperatures. The effects of the condensation conditions on fractions of ethanol-water vapor were studied to concentrate ethanol in product. The fractional condensers proved to be an effective way to enhance the separation efficiency. Under the optimum fractional condensation conditions, the second condenser showed a flux of 1,329 g/m2 h and the separation factor was increased to 17.2. Furthermore, the long-term operation stability was verified, indicating that the PV system incorporating fractional condensation was a promising approach to separate ethanol from the ethanol-water mixture.

Drinking water treatment using a submerged internal-circulation membrane coagulation reactor coupled with permanganate oxidation.

A submerged internal circulating membrane coagulation reactor (MCR) was used to treat surface water to produce drinking water. Polyaluminum chloride (PACl) was used as coagulant, and a hydrophilic polyvinylidene fluoride (PVDF) submerged hollow fiber microfiltration membrane was employed. The influences of trans-membrane pressure (TMP), zeta potential (ZP) of the suspended particles in raw water, and KMnO4 dosing on water flux and the removal of turbidity and organic matter were systematically investigated. Continuous bench-scale experiments showed that the permeate quality of the MCR satisfied the requirement for a centralized water supply, according to the Standards for Drinking Water Quality of China (GB 5749-2006), as evaluated by turbidity (<1 NTU) and total organic carbon (TOC) (<5mg/L) measurements. Besides water flux, the removal of turbidity, TOC and dissolved organic carbon (DOC) in the raw water also increased with increasing TMP in the range of 0.01-0.05MPa. High ZP induced by PACl, such as 5-9mV, led to an increase in the number of fine and total particles in the MCR, and consequently caused serious membrane fouling and high permeate turbidity. However, the removal of TOC and DOC increased with increasing ZP. A slightly positive ZP, such as 1-2mV, corresponding to charge neutralization coagulation, was favorable for membrane fouling control. Moreover, dosing with KMnO4 could further improve the removal of turbidity and DOC, thereby mitigating membrane fouling. The results are helpful for the application of the MCR in producing drinking water and also beneficial to the research and application of other coagulation and membrane separation hybrid processes.

Development of High-Antifouling PPSU Ultrafiltration Membrane by Using Compound Additives: Preparation, Morphologies, and Filtration Resistant Properties.

In this study, flat sheet asymmetric polyphenylsulfone (PPSU) ultrafiltration membranes with enhanced antifouling properties were prepared with a non-solvent induced phase separation (NIPS) method through compound additives containing a polymeric pore-forming agent, a small molecular non-solvent and a surfactant. The formation processes of the porous asymmetric membranes with different kinds of additives were studied in detail, and the microstructure controllable preparation of membrane was achieved by establishing a bridge between the membrane preparation parameters and separation performances. All prepared membranes were characterized by using a scanning electron microscope (SEM), contact angle analysis, porosity, maximum pore size, water and BSA solution permeability studies. The performance efficiency of the membrane was evaluated by using BSA as a model foulant in terms of permeability, solute rejection (R), Rm (membrane inherent resistance), Rc (cake layer resistance), and Rp (pore plugging resistance). The results showed that when the compound additives were used, the inter-connected pores were observed, maximum pore size, contact angle and membrane filtration resistance decreased, while the porosity increased. When PVP compound additives were added, the water flux increased from 80.4 to 148.1 L/(m²·h), the BSA rejection increased from 53.2% to 81.5%. A similar trend was observed for membranes with added PEG compound additives; the water flux and BSA rejection simultaneously increased. The filtration resistance decreased as a result of compound additives. The uniformity of membrane and the number of effective pores could be enhanced by adding compound additives through the cooperation of different additives.

Layer-by-Layer Fabrication of High-Performance Polyamide/ZIF-8 Nanocomposite Membrane for Nanofiltration Applications.

The conventional blending fabrication for thin-film nanocomposite (TFN) membranes is to disperse porous fillers in aqueous/organic phases prior to interfacial polymerization, and the aggregation of fillers may lead to the significant decrease in membrane performance. To overcome this limitation, we proposed a novel layer-by-layer (LBL) fabrication to prepare a polyamide (PA)/ZIF-8 nanocomposite membrane with a multilayer structure: a porous substrate, a ZIF-8 interlayer, and a PA coating layer. The PA/ZIF-8 (LBL) membrane for nanofiltration applications was prepared by growing an interlayer of ZIF-8 nanoparticles on an ultrafiltration membrane through in situ growth and then coating it with an ultrathin PA layer through interfacial polymerization. The obtained PA/ZIF-8 (LBL) membrane exhibited both better permeance and selectivity than did the conventional PA/ZIF-8 TFN membrane because of the ZIF-8 in situ growth producing a ZIF-8 interlayer with more ZIF-8 nanoparticles but fewer aggregates. Compared with the pure PA membrane (the flux of 11.2 kg/m(2)/h and rejection of 99.6%) for dye removal, the obtained PA/ZIF-8 (LBL) membranes achieved a significant improvement in membrane permeance and selectivity. (Flux was up to 27.1 kg/m(2)/h, and the rejection reaches 99.8%.) This LBL fabrication is a promising methodology for other polymer nanocomposite membranes simultaneously having high permeance and good selectivity.

Coagulation pretreatment of highly concentrated acrylonitrile wastewater from petrochemical plants.

Acrylonitrile (AN) wastewater is a heavily polluted and a likely hazardous liquid that is generated during the production of AN. Several chemical methods for the pretreatment of AN wastewater are available in laboratory scale. However, the harsh reaction conditions and high operational cost make these methods undesirable. Until now, four-effect evaporation is the only pretreatment method used for AN wastewater in industry despite its huge energy consumption and high cost. It is difficult to find an energy-saving pretreatment technique from the perspective of industrial application. In this study, a safe and low-cost coagulation technique was developed for the pretreatment of AN wastewater. Three types of inorganic coagulant and three types of polymer coagulant were investigated for the coagulation treatment of highly concentrated AN wastewater from petrochemical plants. The effects of coagulant type, dosage, and coagulation conditions on the pretreatment efficiency of AN wastewater were investigated. The results show that a combination of inorganic and polymer coagulants is effective for the pretreatment of AN wastewater.

Preparation of poly(phthalazinone-ether-sulfone) sponge-like ultrafiltration membrane.

Poly(phthalazinone-ether-sulfone) (PPES) polymer is a relatively newly developed material with a bis(4-fluorodiphenyl) sulfone group. The formation of the PPES membrane by wet-phase inversion can proceed according to a slow or fast gelation method. These formation mechanisms were studied experimentally. The resulting membrane morphology was investigated using both optical and scanning electron micrography. The effects of PPES concentration and two additives, polyvinylpyrrolidone (PVP) and oxalic acid (OA), on the apparent viscosity and gelation rate of PPESK/NMP solutions and membrane performance have also been investigated. It was found that the gelation rate is important to obtain a sponge-like membrane structure, however favored by a fast gelation rate. The membrane obtained by a fast gelation rate showed a high pure water flux and rejection of bovine serum albumin (BSA), contrary to previous findings. On the basis of the experimental results, the actual membrane structure and pure water flux were related, and in agreement with the optical micrograph and gelation rate, respectively. The current results provide a fundamental insight in this novel copolymer, useful in future applications, especially in the membrane formation process.

Enhanced pervaporation performance of multi-layer PDMS/PVDF composite membrane for ethanol recovery from aqueous solution.

Multi-layer PDMS/PVDF composite membrane with an alternative PDMS/PVDF/non-woven-fiber/PVDF/PDMS configuration was prepared in this paper. The porous PVDF substrate was obtained by casting PVDF solution on both sides of non-woven fiber with immersion precipitation phase inversion method. Polydimethylsiloxane (PDMS) was then cured by phenyltrimethoxylsilane (PTMOS) and coated onto the surface of porous PVDF substrate one layer by the other to obtain multi-layer PDMS/PVDF composite membrane. The multi-layer composite membrane was used for ethanol recovery from aqueous solution by pervaporation, and exhibited enhanced separation performance compared with one side PDMS/PVDF composite membranes, especially in the low ethanol concentration range. The maximum separation factor of multi-layer PDMS/PVDF composite membrane was obtained at 60 degrees C, and the total flux increased exponentially along with the increase of temperature. The composite membrane gave the best pervaporation performance with a separation factor of 15, permeation rate of 450 g/m(2)h with a 5 wt.% ethanol concentration at 60 degrees C.

Pervaporation separation of thiophene-heptane mixtures with polydimethylsiloxane (PDMS) membrane for desulfurization.

Cross-linked polydimethylsiloxane (PDMS)-polyetherimide (PEI) composite membranes were prepared, in which asymmetric microporous PEI membrane prepared with phase inversion method was acted as the microporous supporting layer in the flat-plate composite membrane. Membrane characterization was conducted by Fourier transform infrared and scanning electronic microscopy analysis. The composite membranes were employed in pervaporation separation of n-heptane-thiophene mixtures. Effect of amount of PDMS, cross-linking temperature, amount of cross-linking agent, and cross-linking time on the separation efficiency of n-heptane-thiophene mixtures was investigated experimentally. Experiment results demonstrated that 80-100 degrees degrees C of cross-linking temperature was more preferable for practical application, as the amount of cross-linking agent was up to 20 wt.%, and 25 wt.% of PDMS amount was more optimal as far as flux and sulfur enrichment factor were concerned. In addition, the swelling degree of and stableness of composite membrane during long-time operation were studied, which should be significant for practical application.

[Measurement of diffusion coefficients of polar solvent and nonpolar solvent at infinite dilution in polyethylene].

Gas chromatography is a new, fast, accurate and convenient technique to study the correlation of small molecule solvents and polymer membrane materials. It can measure many parameters of dissolution and diffusing characters of a small molecule in a polymer. The retention times and the peak widths at half-height of five small molecule solvents (n-hexane, n-heptane, n-decane, ethanol and water) in the stationary phase of polyethylene were measured. The diffusion coefficients of the small molecule solvents at infinite dilution were calculated with van Deemter equation. The graph plotted according to the results of the diffusion coefficients of n-decane at infinite dilution vs temperatures agreed with the Arrhenius equation. The variance in the diffusion coefficients at infinite dilution of five small molecule solvents was analyzed according to the differences in molecular mass and polarity.