Abstract
In this paper, the authors manufactured for trial a casting apparatus to improve the atability of the characteristics of experimental reverse oεmosis membranes of Loeb's type (formamide system).
The casting apparatus mainly consisted of a doctor knife, a hopper, a shifter of a motor-operated knife and an apparatus for taking out a glass plate, and it was set in a container kept in constant atmospheric conditions. The size of the membrane which could be made by this apparatus was one meter in length and 20 centi-meters in width. By this apparatus, no pin-holes were made in the membrane because the casting solution of the membrane flowed in the form of film on the glass plate at constant velocity, thereby bringing in no air.
The rate of salt rejection and the coefficient of water flux of the membranes prepared by this apparatus under those conditions that the casting atmosphere was aceton gas and the evaporating temperature was 5°C, was 98.2±0.5%, 0.72±0.06 1/m2 hr. atm., while those of the membranes prepared by the existing hand-operated apparatus were 96.3±2.4%, 0.89±0.31 l/m2 hr. atm.
As the result, this apparatus proved to be superior to the existing apparatus in the stability of membrane characteristics.
