1. Department of Chemical Engineering Separation Processes – 1 Module -1 Membrane Separation Processes Prof. Mohammad Asif Room 2B45, Building 3 http://faculty.ksu.edu.sa/masif Tel: +966 1 467 6849

2. Module -1 BooksMain Topic Separation Process Principles, 3rd Edition ISBN: 978-0470481837 J. Seader, E. Henley, D. Roper Text Book Transport Processes and Separation Process Principles, 4 edition Prentice Hall ISBN: 978-0131013674 C. J. Geankoplis Reference Book

3. Lecture Schedule Till Semester Break EventTopicsDatesWeek Introduction1 Module 12 Surprise QuizModule 13 4 5 6 7 Test 1: MondayModule 28

4. Lecture Sequence: Module 1 General introduction Industrial applications Membrane material Membrane modules Module flow patterns Module cascades Transport in membranes Concentration polarization Reverse osmosis Gas permeation Dialysis

5. Membrane based separation processes Reverse osmosis: Transport of solvent in the opposite direction, against the concentration gradient, is affected by imposing a pressure, higher than the osmotic pressure, on the feed side using a nonporous membrane. Dialysis: Transport by a concentration gradient of small solute molecules through a micro- porous membrane. Smaller molecules are able to pass through the membrane. Microfiltration: A microporous membrane selectively allow passage of small solute molecules/solvent. This prevents passage of large dissolved molecules and suspension. Microfiltration retains 0.02 to 10 µm while Ultrafiltration retains 1 to 20 nm. Gas permeation: This involves separation of gas mixtures. The pressure on feed side is much higher than permeate side. Pervaporation The phase on one side of the pervaporation membrane is different from that on the other. Feed to the membrane module is a liquid mixture.

6. DIALYSIS

7. Applications of dialysis include: Hemodialysis, in which urea, creatine, uric acid, phosphates, and chlorides are removed from blood without removing essential higher- molecular weight compounds and blood cells in a device called an artificial kidney. Recovery of sodium hydroxide from a 17–20 wt% caustic viscose liquor contaminated with hemicelluloses to produce a diffusate of 9–10 wt% caustic. Recovery of chromic, hydrochloric, and hydrofluoric acids from contaminating metal ions Recovery of sulfuric acid from aqueous solutions containing nickel sulfate. Recovery of nitric and hydrofluoric acids from spent stainless steel pickle liquor Removal of mineral acids from organic compounds. Removal of low-molecular-weight contaminants from polymers. Purification of pharmaceuticals.

8. EXAMPLE : Recovery of H2SO4 by Dialysis A countercurrent-flow, plate-and-frame dialyzer is to be sized to process 0.78 m 3 /h of an aqueous solution containing 300 kg/m 3 of H 2 SO 4 and smaller amounts of copper and nickel sulfates, using a wash water sweep of 1.0 m 3 /h. It is desired to recover 30% of the acid at 25 0 C. From batch experiments with an acid-resistant vinyl membrane, in the absence of external mass-transfer resistances, a permeance of 0.025 cm/min for the acid and a water-transport number of +1.5 are measured. Membrane transport of copper and nickel sulfates is negligible. Experience with plate-and-frame dialyzers indicates that flow will be laminar and the combined external liquid-film mass-transfer coefficients will be 0.020 cm/min. Determine the membrane area required in m 2.