Removing gallic acid from tanning solns. - by ultrafiltration using asymmetrical membrane

摘要

Gallic acid (I) is removed from a tannin soln. by membrane filtration using an asymmetrical membrane having the following properties: (a) NaCl retention capacity of 0-10% using a 1 g/l NaCl soln.; (b) a polyethyleneglycol retention capacity of 0-40% using a 1 g/l soln. of polyethyleneglycol with a mol.wt. of 1500; (c) a polyethyleneglycol retention capacity of 0-50% using a 1 g/l soln. of polyethylene glycol with a mol.wt. of 4000; (d) a demineralised water flux of at least 10 1/m2.h.100 kPa; (e) a gallic acid retention capacity of at least 10% using a 1 g/l soln. of (I); and (f) a tannin retention capacity of 20-99% using a 1 g/l soln. of tannin. The membrane filtration is carried out at a press. of 1500 kPa, a longitudinal flow rate of 2.36 m/sec and a temp. of 25 deg.C.