Mass Transfer & Separation Processes (Membrane Separation) - Cairo University Lecture Notes - PDF

Title Mass Transfer & Separation Processes Membrane Separation Chemical Engineering Department Faculty of Engineering Cairo University...

Title Mass Transfer & Separation Processes Membrane Separation Chemical Engineering Department Faculty of Engineering Cairo University Prepared by Dr. Ahmed Fayez Nassar A. F. Nassar 1 Contents of the Lecture Introduction Basic Concept and Terminologies Types of Membranes and Membrane Materials Membranes Shapes and Modules Membrane Separation Processes A. F. Nassar 2  References 1. Seader, J.D., Henley, E.J. & Roper, K. “Separation Process Principles”, Wiley, 3rd ed, 2005. (Ch. 14) 2. Baker, R. “Membrane Technology and Applications”, Wiley, 3rd ed, 2012. A. F. Nassar 3 Introduction Membrane separation is a process where a feed consisting of a mixture of two or more components is partially separated by means of a semipermeable barrier (the membrane) through which some species move faster than others. Membrane separation is applied for gases and liquids. The barrier is most often a thin, nonporous, polymeric film, but may also be porous polymer, ceramic, or metal material. To maintain selectivity, the barrier must not dissolve, disintegrate, or break. A. F. Nassar 4  Introduction: Industrial Applications Reverse osmosis: Ultrafiltration: Desalinization of brackish water Concentration of milk to produce cheese Treatment of wastewater Clarification of fruit juice Treatment of surface and groundwater Purification of proteins and DNA, antigens, Concentration of foodstuffs and antibiotics from clarified cell broths Removal of alcohol from beer Color removal in papermaking Dialysis: Pervaporation: Separation of NiSO4 from H2SO4 Dehydration of ethanol–water azeotrope Hemodialysis (‫)غسيل الكلى‬ Removal of water from organic solvents Electrodialysis: Removal of organics from water Production of table salt from seawater Gas permeation: Concentration of brines from RO Separation of CO2 or H2 from methane Wastewaters treatment of electroplating Separation of uranium isotopes Demineralization of cheese whey Adjustment of H2/CO ratio in syn gas Production of ultra-pure water for the Separating air into N2 & O2 rich streams semiconductor industry Recovery of He Microfiltration: Recovery of CH4 from biogas Sterilization of liquids, gases, and drugs Liquid membranes: Clarification and biological stabilization of Recovery of Zn from wastewater in the beverages viscose fiber industry Purification of antibiotics Recovery of Ni from electroplating solutions A. F. Nassar 5 A. F. Nassar 6  Basic Concepts and Terminologies Retentate (reject): The part of the feed that does not pass through the membrane Permeate: The part that does pass through the membrane. Sweep: is a liquid or gas used to facilitate removal of the permeate. A. F. Nassar 7 Basic Concepts and Terminologies Permeance of a membrane A membrane must possess high permeance and a high permeance ratio (selectivity) for the two species being separated. The permeance is analogous to a mass-transfer coefficient. The molar flux, 𝑁 ,of species 𝑖 through a membrane is: 𝑚𝑜𝑙 𝑜𝑟 𝑣𝑜𝑙 𝑃 𝑁 = 𝑑𝑟𝑖𝑣𝑖𝑛𝑔 𝑓𝑜𝑟𝑐𝑒 = 𝑃 𝑑𝑟𝑖𝑣𝑖𝑛𝑔 𝑓𝑜𝑟𝑐𝑒 𝑚. 𝑠𝑒𝑐 𝑙 𝑃 : permeability, and 𝑃 : permeance, 𝑙 : thickness of the membrane, the driving force is conc., partial pressure, etc. 𝑐𝑚 𝑆𝑇𝑃 𝑐𝑚 𝑃 = barrer 10 𝑐𝑚 𝑠 𝑐𝑚𝐻𝑔 𝑘𝑚𝑜𝑙 𝑚 barrer × 3.348 × 10 =1 𝑚 𝑠 𝑃𝑎 A. F. Nassar 8  Basic Concepts and Terminologies Example A silica-glass membrane, 2 m thick with pores