Structural analysis and modeling of the commercial high performance composite flat sheet membranes for membrane distillation application

Direct contact membrane distillation (DCMD) module was operated with three flat sheet commercial membranes (PTFE/PP 1.0, PTFE/PP 0.45, and PTFE/PE 0.45) under various operating conditions. High flux was observed when the PTFE/PP 1.0 membrane was used and there was no membrane wetting when the feed concentration was up to 3.0 M as NaCl. In order to understand the relationship between membrane characteristics and operating conditions, the heat and mass transfer models were employed. Instrumental analyses (SEM, porosimetry and contact angle analysis) were carried out for the membrane characteristics and thermo-hydrodynamic parameters were calculated under given experimental conditions. High flux of PTFE/PP 1.0 membrane was thermodynamically possible because the flow in the feed side was not fully developed in the water channel of the module. The membrane characteristics, such as pore-size of active layer and porosity and thickness of support layer were also attributed to a high flux of PTFE/PP 1.0 membrane. © 2014 Elsevier B.V. All rights reserved.

Three candidate MD membranes (PTFE/PP 1.0, PTFE/PP 0.45 and PTFE/PE 0.45) were tested under given experimental conditions. Membrane characteristic were analyzed by instrumental approaches and thermo-hydrodynamic status was computed by the heat and mass transfer modeling. The PTFE/PP 1.0 bi-composite membrane showed the high flux (190 LMH) in the DCMD configuration. The electronic conductivities in the permeates were maintained between 0.8 and 1.9 μS/cm at the end of the tests, which means that no membrane wetting occurred during the MD operation. The major reasons for the high flux of PTFE/PE 1.0 membrane were pertinent membrane characteristics, such as large pore size of active layer and highly porous and thermal conductive support layer and [1] M. Khayet, Membranes and theoretical modeling of membrane distillation: a review, Adv. Colloid Interf. Sci. 164 (2011) 56–88. [2] S. Al-Obaidani, E. Curcio, F. Macedonio, G. Di Profio, H. Al-Hinaid, E. Drioli, Potential of membrane distillation in seawater desalination: thermal efficiency, sensitivity study and cost estimation, J. Membr. Sci. 323 (2008) 85–98. [3] J. Phattaranawik, R. Jiraratananon, A.G. Fane, Effect of pore size distribution and air flux on mass transport in direct contact membrane distillation, J. Membr. Sci. 215 (2003) 75–85. [4] M. Gryta, Influence of polypropylene membrane surface porosity on the performance of membrane distillation process, J. Membr. Sci. 287 (2007) 67–78. [5] L. Mart'ınez, J.M. Rodr'ıguez-Maroto, Membrane thickness reduction effects on direct contact membrane distillation performance, J. Membr. Sci. 312 (2008) 143–156. [6] L. Dumée, V. Germain, K. Sears, J. Schütz, N. Finn, M. Duke, S. Cerneaux, D. Cornu, S. Gray, Enhanced durability and hydrophobicity of carbon nanotube bucky paper membranes in membrane distillation, J. Membr. Sci. 376 (2011) 241–246. [7] A. Alkhudhiri, N. Darwish, N. Hilal, Membrane distillation: a comprehensive review, [8] [8] P.K. Weyl, Recovery of demineralized water from saline waters, United States Patent 3,340,186 (1967) [9] K.W. Lawson, D.R. Lloyd, Membrane distillation, J. Membr. Sci. 124 (1997) 1–25. [10] X. Wei, B. Zhao, X.-M. Li, Z. Wang, B.-Q. He, T. He, B. Jiang, CF4 plasma surface modification of asymmetric hydrophilic polyethersulfone membranes for direct contact membrane distillation, J. Membr. Sci. 407–408 (2012) 164–175. [11] L. DeLorenzo, E. Tocci, A. Gugliuzza, E. Drioli, Assembly of nanocomposite PEBAX membranes: a complementary study of affinity and clusterization phenomena, J. Membr. Sci. 421–422 (2012) 75–84. [12] C. Feng, K.C. Khulbe, T. Matsuura, S. Tabe, A.F. Ismail, Preparation and characterization of electro-spun nanofiber membranes and their possible applications in water treatment, Sep. Purif. Technol. 102 (2013) 118–135. [13] S. Adnan, M. Hoang, H. Wang, Z. Xie, Commercial PTFE membranes for membrane distillation application: effect of microstructure and support material, Desalination 284 (2012) 297–308. [14] J. Zhang, N. Dow, M. Duke, E. Ostarcevic, J.-D. Li, S. Gray, Identification of material and physical features of membrane distillation membranes for high performance desalination, J. Membr. Sci. 349 (2010) 295–303. [15] H.J. Hwang, K. He, S. Gray, J. Zhang, I.S. Moon, Direct contact membrane distillation (DCMD): experimental study on the commercial PTFE membrane and modeling, J. Membr. Sci. 371 (2011) 90–98.