Membranes Minimum solvent rate

Design of the membrane module system involves selection of the membrane material the module geometry, eg, spiral-wound or hollow-fiber product flow rate and concentration solvent recovery operating pressure and the minimum tolerable flux (9,11). The effects of these variables can be obtained from laboratory or pilot experiments using different membranes and modules. The membrane module as well as the solvent recovery can be chosen to minimize fouling. Spiral-wound modules are widely used because these offer both high surface area as well as a lower fouling potential. 

Purification by pressure column chromatography on silicagel is conducted as follows. A glass column (inner diameter 5 cm, length 51 cm) is filled with a slurry of silica (450 g of silicagel, Acros, 0.035-0.070 mm, pore diameter 6 nm) in 95 5 (v v) CH2Cl2/acetone. A 3-g portion of cmde [AsPl JL is dissolved in a minimum amount of solvent and adsorbed on the top of the column. The column is connected with a membrane pump (output pressure 1.6 bar) and then eluted at a flow rate of about 180 mL/min. The violet fraction is collected and evaporated on a rotary evaporator. This chromatographic separation on the whole lasts 8 h. 

---