Membrane Distillation: Experimental evaluation of Liquid Entry Pressure in commercial membranes with textile dye solutions

In Membrane Distillation, the Liquid Entry Pressure (LEP) determination is crucial to ensure permeate quality. While the process has been increasingly applied to dyeing wastewater, the influence of dye class on LEP has not been evaluated yet. In the present work, the experimental evaluation of LEP was carried out with four classes of textile dyes (reactive, disperse, acid, and direct) and the three commercial membranes most used (PTFE, PP, and PVDF). The influence of dye class on LEP was associated with analyses as liquid surface tension, ATR-FTIR spectroscopy, and degree of liquid absorption. Acid and direct classes presented a higher tendency to membrane wetting due to the very low LEP values. On the other hand, reactive and disperse dye classes maintained high LEP values throughout the tests for the PTFE and PVDF membranes. The PP membrane showed lower LEP values, intermediate liquid absorption, and the highest permeate flux. The wetting phenomenon was avoided due to the high LEP values observed for reactive and disperse dyes, indicating that commercial membranes are potential candidates for implantation on an industrial scale, which can speed up the MD commercialization process in the textile industry. • LEP values are influenced by different classes of textile dyes. • Acid class presented very low LEP values with a higher propensity to wetting. • Low LEP was obtained for direct class with the PP membrane. • High LEP values were observed for reactive and disperse classes. • Stable DCMD operation for solutions containing reactive or disperse classes