Alternative Separations Eli Gronowski CBE 562

Overview Membranes Absorbents Ion-Exchange Resins

Membranes Thin films of porous material Polymer Films Ceramics Carbon Fiber Porous Metal Substrates Size: < 10 Angstroms to 100+microns

Types of Membranes Microporous Membranes Homogeneous Membranes Separate by pore diameter and particle size Homogeneous Membranes Dense film Separation by pressure, concentration or electrical potential gradient Separation of similar size particles

Types of Membranes Asymmetric Membranes very thin (0.1-1.0 micron) skin layer on a highly porous (100-200 microns) thick substructure Thin skin acts as the selective membrane

Types of Membranes Electrically Charged Membranes Electrodialysis ions are transported through a membrane from one solution to another under the influence of an electrical potential. production of potable water from sea or brackish water ED can be utilised to perform several general types of separations such as separation and concentration of salts, acids and bases from aqueous solutions or the separation and concentration of monovalent ions from multiple charged components or the separation of ionic compounds from uncharged molecules.

Microfiltration membrane Most widely used Sterile filtration Pores (0.1-10.0 microns) Material can be selective Mechanical strength Temperature resistance Chemical compatibility Hydrophobility MF has a wide array of applications as mentioned below: Preparation of parenterals and sterile water for pharmaceutical industry Food & beverages (concentration of fruit juices and alcoholic beverages Chemical industry Microelectronics industry Fermentation Laboratory/analytical uses etc. Polyvinylidene difluoride

Hydrophobic membranes Resists water while simultaneously venting gases Materials Polytetrafluoroethylene (PTFE), nylon, glass fibers, polyethersulfone

How Does It work Surface Tension Polarity Differences Only liquids with surface energy lower than that of the membrane can wet out the membrane. Polarity Differences Nonpolar membranes tend to resist passage of polar compounds Polyvinylidene fluoride Two main principiles

Applications Underwater flashlights Auto Industry Vent hydrogen gas from Batteries Auto Industry Vent Heat / Gases Windshield wiper motors Halogen headlights

Most Popular Applications Hemodialysis Reverse osmosis Micro/Ultra Water Filtration In hemodialysis, blood flows through a semipermeable cellulose acetate membrane. This membrane separates proteins and cellular constituents in the blood from smaller molecular solutes. The solutes are then discharged from the apparatus allowing for pure blood to be generated back into the body.

Membrane Industry

Growth Fueled by Regulations for potable water/wastewater Industrial recovery/recycling

Benefits Separations Require Energy Distillation Membranes typically require a lower amount of energy

Reduction of Energy Costs Replace Typical Units Ops Ethylene Production C2 Splitter

Membrane Advantages Energy savings Clean technology with operational ease Replaces the conventional processes Filtration Distillation Produces high quality products Greater flexibility in designing systems.

Membrane Disadvantages Membranes are expensive. Certain solvents can quickly and permanently destroy the membrane. Certain solids, especially graphite, can permanently foul the membrane surface.

Absorbents MOLECULAR SIEVE crystallized synthetic zeolite Selective, microporous adsorbent Premium catalyst and catalytic carrier Ion exchanger. Contains a network of uniform pores and empty cavities Zeolite is an inorganic porous material having a highly regular structure of pores and chambers that allows some molecules to pass through, and causes others to be either excluded, or broken down. It is in many ways, the inorganic equivalent of organic enzymes, many of which also have specific sized chambers that trap chemicals within our bodies, holding them where they either break down, or react with specific chemicals.

Molecular Sieve

Ethanol-Water System

Ion Exchange Resin Water Softeners Ion exchange resins are insoluble polymers that contain acidic or basic functional groups and have the ability to exchange counter-ions within aqueous solutions surrounding them

Pharmaceutical Technology Drug resinate more stable than original drug. Vitamin B12 (2 months vs 2 Years) Drug Abuse Control Reduce the “High” This technology is still used commercially today, more than 40 years after it was first introduced

Future of Separations Advancements in Membrane Tech Chemical Industry Better Materials Higher Selectivity, Stability, Throughput Chemical Industry Gas Separations Cryogenic distillation Selective adsorption

References http://www.edmwt.com/membrane.htm Using Hydrophobic Membranes to Protect Gas Sensors http://www.sensorsmag.com/articles/0598/gas0598/main.shtml Clean Technologies and Environmental Policy. Berlin: Apr 2004. Vol. 6, Iss. 2;  pg. 78 Pharmaceutical Technology. Cleveland: 2004.  pg. 20, 5 pgs http://www.njit.edu/alumni/pdf/BeertoBlood.pdf http://www.tifac.org.in/news/memb.htm