The sepiolite membrane for ultrafiltration

Novel inorganic membranes were prepared from clay (sepiolite) suspensions, which were formed by dispersing clay particles in water either by applying ultrasonic wave or by magnetic stirring. Films can be formed easily from such suspensions due to fibrous nature of sepiolite. Thus, this offers a method much simpler than the conventional sol–gel method. The membranes were further tested for ultrafiltration of polyethylene glycol and polyethylene oxide solutes of different molecular weights. It was found that the correlation between the separation and the Einstein–Stokes radius of solute fits the log-normal distribution very well. The mean pore size of 23–26 nm and the standard deviation of 1.91–2.04 were obtained from the above correlation. It was also found that the mean pore size and the pore size distribution did not depend very much on the membrane preparation method.