4(%3)3 - Ecole nationale supérieure de chimie de Montpellier

esistance curves obtained from flux curves before perforation (red), just after perforation (blue) and after healingprocess (green) thickness, which is a major damage to the material. In general, the R value should converge over time tothe 1 st run curve of undamaged membrane, if healing has occurred. As expected, the initial R value of thevirgin membrane (Red Curve, 1st run) dramatically decreases immediately after the perforation (BlueCurve, 2nd run). A third run (Green Curve, 3rd run) was carried out 24 hours later to verify the stability ofthe healing phenomenon. To verify the role of pressure as a necessary stimulus for self-healing, some ofthe perforated membranes were immersed for one month in water under static conditions as comparedto other membranes subjected to water flux however no augmentation in resistance was observed. Atvery low pressure of 0.04 bar (Figure – 2.17b), very little resistance recovery was measured even after 15hr while at 1.5 bar and beyond (Figure – 2.17g, h), the resistance again failed to achieve its original value.These results indicated that there is a pressure range (0.07-0.8 bar) (Figure – 2.17c-f) in which thehealing process takes place effectively (Figure – 2.18).For a given perforation of 110 µm at 0.8 bar, 100 %recovery of resistance was achieved effectively within 40 minutes.R recovery %100908070605040P=2.5 barP=1.5 barP=0.8 barP=0.6 barP=0.2 barP=0.07 bar30P=0.04 bar201000 1 2 3 4Time (hr)Figure – 2.18: % recovery of fluid flow resistance calculated with respect to time.65