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1、Chapter 8 Functional Polymers,8.1 Introduction 8.1.1 Definition of functional polymers,Functional polymer according to IUPAC (a) a polymer bearing functional groups (such as hydroxyl, carboxyl, or amino groups) that make the polymer reactive, (b) a polymer performing a specific function for which it
2、 is produced and used. A polymer that exhibits specified chemical reactivity or has specified physical, biological, pharmacological, or other uses,8.1.2 Classification of functional polymers,Biodegradable polymer Conducting polymer Electroluminescent polymer Ferroelectric polymer Ferromagnetic polym
3、er Impact-modified polymer Liquid-crystalline polymer Macroporous polymer Non-linear-optical polymer Optically-active polymer Photoelastic polymer Photoluminescent polymer Photosensitive polymer,Piezoelectric polymer Polyelectrolyte Polymer sorbent Polymer compatibilizer Polymer drug Polymer gel Pol
4、ymer membrane Polymer solvent Polymer support Polymer surfactant Resist polymer Shape-memory polymer Superabsorbent polymer,8.1.3 Applications and outlook of functional polymers,Applications: Organic catalysis (supported catalysts) Medicine (red-blood-cell substitutes) Optoelectronics (conducting po
5、lymers Magnetic polymers and polymers for nonlinear optics) Biomaterials Paints and varnishes Building materials Photographic materials Lube and fuel additives,8.2 Membrane 8.2.1 Introduction,History Initiator of all crossflow membrane technology Dr. Sourirajan, removed salt from seawater, in the la
6、te 1950s. Commercial RO & UF membranes occurred in the early 1970s. Crossflow membrane processes became well accepted in industry and medicine in the 1980s. Widely used today.,History of membrane,Membrane a selective barrier for separating certain species in a fluid No phase change Pore sizes determ
7、ining the sieved particles Separation, concentration, fractionation & purification,Characters,Membrane configurations,Porous membrane （多孔膜） MF， UF，NF Dense membrane （致密膜） ED，RO，GS，PV，VP,Classification of membranes,Symmetric membrane Asymmetric membrane,Structure of porous membranes,Fig. 5 Schematic
8、diagram of a) a symmetric and b) an asymmetric membrane,Schematic diagram of the filtration behavior of a) an asymmetric and b) a symmetric membrane,a b,Classification of membranes according to driving force,Classification,Process of dead-end pressure-driven membrane filtration,Classification,Proces
9、s of cross-flow pressure-driven membrane filtration,Classification,8.2.2 Crossflow Membrane Technology,Four categories: Osmosis (RO) Nanofiltration (NF) Ultrafiltration (UF) Microfiltration (MF),Crossflow Membrane Technology,Microfiltration (MF),Pore sizes: 0.05 to 3 m Transmembrane pressures (TMP):
10、 550 psi (0.33.3 bar) Cross-flow velocities: 36 m/s in tubular modules Applications: starch, bacteria, molds, yeast and emulsified oils,Crossflow Membrane Technology,Ultrafiltration (UF),Pore sizes: 0.005 to 0.1 m Transmembrane pressures (TMP): Higher than MF Cutoff molecular weight: About 1,000 to
11、500,000 Concentrate high molecular weight species while allowing dissolved salts and lower molecular weight materials to pass through the membrane.,Crossflow Membrane Technology,Nanofiltration (NF),Pore sizes: close to one nanometer diameter (10 ) Transmembrane pressures (TMP): Higher than UF Cutoff
12、 molecular weight: 200 300 Application: Water softening Cheese-whey desalting RO pretreatment Pharmaceutical concentration Kidney dialysis units Maple sugar concentration.,Crossflow Membrane Technology,Reverse osmosis (RO),Pore sizes: 4 to 8 Transmembrane pressures (TMP): 35100 atm Cutoff molecular
13、weight: 25 and 150 Rejection mechanism: “surface-force-pore flow“ theory “solution-diffusion“ theory,Crossflow Membrane Technology,Typical Operating Pressures - psig (bar*),Crossflow Membrane Technology,Electrodialysis Removal of ionic species from non-ionic products Pervaporation Separation of liqu
14、id mixtures by partial vaporization through a permselective membrane Phase change occurs,Crossflow Membrane Technology,Dialysis A concentration-driven diffusion Application: Separation of proteins and other macromolecules from salts in pharmaceutical and biochemical applications, e.g., hemodialysis,
15、Crossflow Membrane Technology,8.2.3 Membrane materials,Most of membranes are made of polymeric materials, e.g. Polysulfone (PSF) Polyethersulfone (PES) Polyphenylsulfone (PPSU) Polyvinylidene Fluoride (PVDF) Polypropylene (PP) Polyethylene (PE) Cellulose and Cellulose acetates (CA) Polyamide (PA) Po
16、lyacrylonitrile (PAN) Polytetrafluoroethylene (PTFE),RO membrane materials CA membranes Tolerate chlorine at levels used for microbial control PA membranes Higher rejection and flux Tolerate a wider pH range Sulfonated PSF membranes NF membrane materials PA membranes CA membranes,UF membrane materia
17、ls CA membranes PVDF membranes PSF membranes Tolerate a pH range of 0.5 to 13, temperatures to 85C (185F), and 25 mg/L of free chlorine on a continuous basis MF membrane materials PA membranes CA membranes PVDF membranes PC, PP, PE, PTFE,Operating parameters for widely used polymeric RO and UF membr
18、anes,8.2.4 Membrane elements,Crossflow membrane configuration comparison,8.2.5 Machines and systems,A simple machine for membrane systems includes: A pump provide the driving pressure and crossflow velocity Housing elements Connecting plumbing Control valve(s) Pressure gauges Motor controls,Membrane
19、 systems often need a pretreatment equipment to reduce membrane fouling They can be preceded or followed by other unit processes such as degasification or activated carbon adsorption e.g., For ultrapure water applications, two-pass RO systems have replaced many RO-DI systems.,8.2.6 Design considerat
20、ion Important parameters,A balance of flow and pressure Higher-pressure causes higher permeate, also causes more severe fouling Higher crossflow velocity reduces fouling.,Recovery the ratio of permeate to feed volume Feedwater applications: 7580% machine recovery, Some UF and RO applications: 5075%
21、Seawater Desalting via RO is typically run as low as 40% due to the very high osmotic pressure generated as the salt in the feed stream is concentrated. Temperature The warmer the feed stream the higher the throughput Solution viscosity,8.2.7 Applications,Hundreds of applications, falling in three b
22、road categories: Water purification Manufacturing process separations Waste treatment.,Water Purification,Boiler feed Potable from brackish or alkaline source Color removal from surface water Microbial removal; bacteria, pyrogens, giardia and cryptosporidium cysts THM precursor and pesticide removal
23、 Potable from seawater Sodium and organics reduction for beverages Reconstituting food and juices Bottled water Can and bottle rinsing,Applications: Water Purification,Rinse water for metal finishing operations Spot-free car wash rinses Laboratory and reagent grade water USP Purified Water and Water
24、 for Injection Semiconductor chip rinsing Distillation and deionization system pretreatment Kidney dialysis Medical device and packaging rinse water Photographic rinse water Pulp and paper rinses and makeup water Dye vat makeup,Applications: Water Purification,Process,Juice and milk concentration Be
25、er and wine finishing Beverage flavor enhancement Cheese whey fractionation/concentration of proteins and lactose Food oils, proteins, taste agents concentration Saccharide purification Maple sap preconcentration Enzymes and amino acids, purification and concentration,Applications: Process,Chemical
26、dewatering Chemical mixtures fractionation Dye and ink Desalting Glycol and glycerin recovery ED paints recovery from rinses Medicine and vitamin concentration purification Blood fractionation Cell broth fractionation Cell concentration Photographic emulsions concentration/purification,Applications:
27、 Process,Waste treatment,Tertiary sewage water recovery Heavy metals and plating salts concentration BOD and COD concentration Dewatering liquid for reduced disposal volume Dilute materials recovery Radioactive materials recovery,Applications: Waste treatment,Textile waste recovery for reuse Pulp an
28、d paper water recovery for reuse Dye and ink concentration and recovery Photographic waste concentration and recovery Oil field “produced water“ treatment Lubricants concentration for reuse Commercial laundry water and heat reuse End of pipe treatment for water recovery,Applications: Waste treatment
29、,8.2.8 Recent advances,Composite membranes RO, UF & NF Improved both flux and separation Increase chemical durability of membranes Surface treatment techniques Adding formal charges to change separation ability and reduce fouling tendency,Enhanced systems controls improved the operational efficiency
30、 Industrys evolving realization treatment systems are often most efficient if they combine several unit processes. Home RO units,8.3 Adsorptive Separation Polymers 8.3.1 Introduction,Adsorption preferential partitioning of substances from the gaseous or liquid phase onto the surface of a solid subst
31、rate Bone char decolorization of sugar solutions and other foods Activated carbon removing nerve gases from the battlefield,Adsorption is different from absorption separation of a substance from one phase accompanied by its accumulation or concentration at the surface of another. Adsorbent the adsor
32、bing phase. Adsorbate the material concentrated or adsorbed at the surface of adsorbent.,Physical adsorption caused mainly by van der Waals forces and electrostatic forces between adsorbate molecules and the atoms which compose the adsorbent surface. Thus adsorbents are characterized first by surfac
33、e properties such as surface area and polarity.,8.3 Adsorptive Separation Polymers 8.3.1 Introduction,Adsorption preferential partitioning of substances from the gaseous or liquid phase onto the surface of a solid substrate Bone char decolorization of sugar solutions and other foods Activated carbon
34、 removing nerve gases from the battlefield,Adsorption is different from absorption separation of a substance from one phase accompanied by its accumulation or concentration at the surface of another. Adsorbent the adsorbing phase. Adsorbate the material concentrated or adsorbed at the surface of ads
35、orbent.,Absorption a process in which material transferred from one phase to another (e.g. liquid) interpenetrates the second phase to form a “solution”. The term “sorption” is a general expression encompassing both processes of absorption and adsorption.,Physical adsorption caused mainly by van der
36、 Waals forces and electrostatic forces between adsorbate molecules and the atoms which compose the adsorbent surface. Thus adsorbents are characterized first by surface properties such as surface area and polarity.,Important indices A large specific surface area A suitable pore size distribution Sur
37、face polarity Polar adsorbents: Hydrophilic Nonpolar adsorbents: Hydrophobic,8.3.2 Historical background,Reference in Bible Aristotles experiment Practice in ancient Egypt, Grace and China,Perhaps Dr. Gans in Germany was the first person who used ion exchanger (processed natural zeolite) to an indus
38、trial scale, based on scientific understanding and technological maturity. Adams and Holmes synthesized organic ion exchangers called ion exchange resins in 1935.,8.3.3 Classification,Ion exchangers are generally insoluble solids or immiscible liquids (in case of liquid ion exchangers) capable of ex
39、changing ions with the surroundings Depending upon their ability of exchanging cations or anions the ion exchangers are either cation or anion exchangers respectively.,A cation exchanger consists of a matrix with a negative charge. An anion exchanger consists of a matrix with a positive charge. The
40、oppositely charged ions called counter ions, compensate the matrix charge.,On the basis of the nature of the matrix an ion exchanger may be organic or inorganic In organic resins the matrix is a highly polymerized crosslinked hydrocarbon containing ionogenic groups. Inorganic ion exchangers are gene
41、rally the oxides, hydroxides and insoluble acid salts of polyvalent metals, heteropolyacid salts and insoluble metal ferrocyanides.,8.3.3.1 Synthetic Inorganic ION Exchangers,The main emphasis has been given to the development of new materials possessing chemical stability, reproducibility in ion ex
42、change behavior and selectivity for certain metal ions important from analytical and environmental point of view. Synthetic inorganic ion exchangers are generally produced as gelatinous precipitates by mixing rapidly the elements of groups 3,4,5 and 6 of the periodic table, usually at room temperatu
43、re.,8.3.3.2 Organic-inorganic ion Exchangers,Traditional organic ion exchangers are found to be unsuitable at high temperatures and under strong radiation. Inorganic ion exchangers are reported to be not very much reproducible in behavior, and not very stable mechanically and chemically because of t
44、heir inorganic nature. Interest has been developed to obtain some organic based inorganic ion exchangers, i.e., hybrid ion exchangers.,Fibrous ion exchange materials can be used in the form of various textile goods such as cloth, conveyer belts, nonwoven materials, staples, nets etc. consist of mono
45、filaments of uniform size ranging between 550 um. This predetermines short diffusion path of sorbent and high rate of sorption that can be of about hundred times higher than that of the granular resins with a particle diameter of 0.251 um, normally used. Has extremely high osmotic stability that all
46、ows them to be used in conditions of multiple wetting and drying occurring at cyclic sorption/regeneration processes in air purification.,e.g., A new class of highly crosslinked polymeric resins (Macronet resins) have been developed with surface areas as high as 1200 m2/g, which approach or exceed t
47、hose of activated carbon in some cases. These resins can be easily regenerated in situ with simple aliphatic alcohols. The Macronet resins are available in a range of different functionalities and thus can be used for selective removal from multicomponent systems.,8.3.4 Adsorbents,Microporous, high
48、specific surface material (200 2000 m2/g ) Alumina (drying) Silicagel (drying) Zeolite molecular sieves (gas & liquid separations, drying) highly specific, single pore size may be fine-tuned: cations + structure A type or LTA X and Y or FAUjasites Mordenite, other natural zeolites Silicalites or ZSM
49、x (hydrophobic, carbon like) Active carbon (gas & liquid separations, guard beds) Carbon molecular sieves (narrow pore distribution),Others: impregnated carbons (Cu-chlorides - CO separation) clays (natural and pillared clays) resins, polymers (biological, ions, large molecules,离子交换树脂,离子交换树脂是带有官能团(有交换离子的活性基团)、具有网状结构、不溶性的高分子化合物。通常是球形颗粒物。,Ion exchange resins,离子交换树脂的结构,带有活性基团的网状高分子聚合物,骨架,活性基团,丙烯酸树脂,聚苯乙烯树脂,交联剂,酸性基团,碱性基团,SO3H,COOH,N+R3