内容说明专外2basic priciplesseparation

1、2014 springTopic 2Membrane separationLecturer: Dr.Chen FangTopic 2 group case study and reportReading material: Silica-based Mesoporous organic-inorganic hybrid material, Angew. Chem. Int. Ed.2006, 45, 3216 3251.Discribe one of three different approches to prepare silica-based mesoporous organic-ino

2、rganic hybrid material,inclurds basic preparing method(mechanism) and current researches applcations.One page slide cover the case study material in “Highly sensitive flexible pressure sensors with microstructured rubber dielectric layers“.As we know, the suckers on octopus tentacles can produce gre

3、at suction force. The way it works is that the sucker is pressed against a surface, and the flexible outer margin of skin conforms to it, forming a seal. The octopus-tentacle-inspired design was conceptualized to fabricate nanosucker structures behaving like a great deal of suckers on the resin surf

4、ace, generating a considerable adhesion force. Furthermore, the dry adhesive could also resist shear force and also normal force, and be easily peeled off from the surface.Open question: What can you Inspired by octopus sucker?Based on the title, what kind of general idea you could imagine through t

5、he research?Try to summarized the key words of this article.OutlineIntroduction to membrane seprationType of membrane sepration techniquesMembrane separationConventional separation unit operations:Distillation 蒸馏Liquid-Liquid Extraction（液-液萃取） Filtration（过滤）Recrystallization（重结晶）Centrifugalization（离

6、心分离）Chromatography(层析）Membrane separation is a type of unit operations, first appears in the beginning of 20th cent. developed by 1960s.The membrane acts as a semipermeable barrier and separation occurs by the membrane controlling the rate of movement of various molecules between two liquid phases,

7、two gas phases, or a liquid and a gas phase. The two fluid phases are usually miscible and the membrane barrier prevents actual, ordinary hydrodynamic flow.Advantages of Membrane Separation.No phase change;Lower energy cost;Ambient temperature operation;No need to add other components;Environmental

8、friendly tech.;Tips about Membrane Separation Key features in Membrane separationMaterials: molecular design of high-performance materials suitable for each separation mode. Morphology: Morphology design of high performance membraneElement/module: element and module design to maintain high performan

9、ce of membraneMembrane process: Plant design and operation technology Membrane classificationShape: Flat-sheet membrane, Hollow fiber membrane, TubularMaterials: Organic and Inorganic membrane Structure: Symmetrical, Asymmetric and composite membraneState: Solid, liquid membraneClassification of mem

10、braneBy pore sizeMicrofiltration membrane微滤膜（MF） Size ExclusionUltrafiltration membrane超滤膜（UF）Size ExclusionNanofiltration membrane纳滤膜（NF）Size ExclusionReverse Osmosis membrane反渗透膜（RO） Solution /diffusionProcessDriving forceSep.SizeCutoff molecular weight (gmol-1)截留分子量Examples(NF） Nanofiltration mem

11、branePressure gradient(0.51MPa)0.1-1nmMacropores200-1000dissolved saltsMF (Microfiltration membrane)Pressure gradient(0.01-0.2Mpa) 0.1-10m MacroporesparticlesUF (Ultrafiltration membrane)Pressure gradient(0.2-1.0Mpa)5nm-0.1mMesopores2000-300,000proteinsRO (Reverse Osmosis membrane)Pressure gradient(

12、2-100Mpa)5nmNo pores25-150dissolved saltsAdvanced Membrane Technologies, Stanford University, May 07, 2008Advanced Membrane Technologies, Stanford University, May 07, 2008Advanced Membrane Technologies, Stanford University, May 07, 2008Ideal RO,UF,MF,NF applicationsBy Morphology of Cross section Hol

13、low fiber（中空纤维） Tubular(管式） Sheet（平板）By Structure: Symmetrical AsymmetricalMembrane modules Membrane modulesMembrane modulesScalable membrane assemblyReverse Osmosis membrane Solution-Diffusion (溶解扩散过程）Solution Diffusion assumptions:Membrane surface layer is homogenous and nonporous Both solute and

14、solvent dissolve in the surface layer and then diffuse across it independently.SWRO processMembrane Fouling Possible negative effects of fouling includes:Membrane flux （膜通量）decline resulting from the formation of permeability-reducing film on the membrane surfaceMembrane biodegradation due to the pr

15、oduction of acidic by-products by microorganisms, which are concentrated at the membrane surface where they can cause the most damage.Increased salt passage thereby reducing the quality of the product waterIncrease in energy consumption. To maintain the same production rate differential pressure and

16、 feed pressure must be increased to counteract the reduction in permeability brought on by the increase in resistance due to fouling. But, damage to the membrane elements may be possible if the operating pressure exceeds the manufactures mendations. Low fouling membrane for wastewater reclamation Ch

17、emical fouling: adsorption of organic matters such as humic substances and surfactants in the feed water onto membrane surface Biological fouling:Microbeadsorption by hydrophobic or electrostatic interaction (reversible )Propagation of micros with nutrition in the feed water(irreversible)Deposition

18、of exhaust materials of biological metabolism(新陈代谢)（irreversible)Low fouling membrane strategies?Homework 生物膜反应器活性污泥Wastewater treatmentWorking principles MBR V.S Sludge Membrane Bioreactor: Definition of MBR The membranes are submerged in the activated sludge tanks to perform the critical solids se

19、paration process that clarifiers(澄清器) and tertiary process units perform in conventional treatment plants Processes with an anoxic zone(缺氧区), aeration zone（通风、换气）, and a membrane zone. Sometimes an anaerobic zone（厌氧区） if biological nitrogen removal is required. Fundamentals of membrane sepration 120

20、Surface polarization (Concentration polarization)表面极化，浓差极化Drawbacks from Surface polarization (CP)?Osmosis pressure increased, flux decreased. Or increasing pressure supply to get same flux.Retention decreasedMain factor cause Membrane fouling by concentration gradient Approaches for reducing surfac

21、e polarization?Reduce the film thickness by increasing turbulent mixing at the membrane surface Increasing fluid flow velocity (promoting mixing)Membrane separate volatile organic compoundsApplications fieldsGasoline vapor recovery Monomer separation in polymer productionSolvent separation from high

22、 organic vapor concentrated off-gas streamsFrontiers in membrane-based organic vapor recovery Research centre Geethacht(GKSS),GermanyMembrane technology and Research (MTR) USNitto Denko, Japan Membranes for organic vapor separation 216The permeability of gas through a membrane depends on it solubili

23、ty and diffusion.Design Criteria 217-218Influence factors of Separation efficiency Operating temperature Temperature chose principle and why?Oxygen and nitrogen, permeability increase with increasing of T.Permeation of organic vapor is governed by its solubility and solubility increases with a decre

24、ase in T.Lower possible temperature.Feed pressureHigher or lower pressure?Feed composition Module design Technical Applications-Gasoline vapor recovery 229RegionsRegulations Emission limitRecovery(%)U.S.EPA Standard35g(HC)/m394-97Europe European Directive 94/63/EC35g(HC)/m394-97Germany TI AIR (section 2.3 and 3.1.7) 0.15g(HC)/m30.005g(Benzene)/m399.99JapanAdmin